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Ladies and gentlemen,Good morning/afternoon/evening. It is my great honor to stand before you today and share with you my thoughts on the challenges that lie ahead in the future, and how we, as the youth, can embrace and overcome them.Firstly, let me begin by acknowledging the incredible progress that our generation has witnessed. We have grown up in an era of rapid technological advancements, where the internet has connected us like never before, and where the possibilities seem endless. However, with these advancements come challenges that we must be prepared to face.The first challenge that we, as the youth, will encounter is the rapid pace of technological change. In just a few decades, we have seen the birth of the internet, smartphones, and artificial intelligence. These advancements have transformed the way we live, work, and communicate. However, they have also created a sense of unease and uncertainty, as we question whether we can keep up with the ever-evolving technological landscape.To overcome this challenge, we must embrace lifelong learning. As the world continues to change, we must be willing to adapt and learn new skills. We should seek out opportunities to gain knowledge and expertise in various fields, ensuring that we remain relevant in an ever-changing job market. Furthermore, we must foster a culture of innovation and creativity, as these qualities will enable us to find solutions to the problems that arise from technological advancements.The second challenge that we face is the growing divide between the rich and the poor. In many parts of the world, wealth and resources are concentrated in the hands of a few, while the majority struggle to make ends meet. This inequality can lead to social unrest and instability, threatening the very fabric of our societies.As the youth, we have a responsibility to address this challenge. We must advocate for social justice and equality, ensuring that everyone has access to the opportunities and resources they need to succeed. We should support initiatives that promote inclusive growth, such as fairtrade, sustainable development, and education for all. By working together, we can create a more equitable world for future generations.The third challenge that lies ahead is the threat of climate change. The Earth is facing unprecedented environmental degradation, with rising sea levels, extreme weather events, and loss of biodiversity. These changes have far-reaching consequences, affecting everything from food security to public health.As the youth, we must take a stand against climate change. We should promote sustainable practices and advocate for policies that prioritize environmental protection. By reducing our carbon footprint, investing in renewable energy, and protecting natural habitats, we can help mitigate the impacts of climate change and ensure a healthy planet for future generations.The fourth challenge is the rise of populism and nationalism. In many parts of the world, we are witnessing a rise in extreme ideologies that threaten peace, stability, and human rights. These ideologies can leadto conflicts, discrimination, and exclusion, undermining the progressthat we have made as a global community.To counter this challenge, we must promote tolerance, understanding, and empathy. We should work towards building a more inclusive society, where people of different backgrounds, cultures, and beliefs can coexist in harmony. By fostering a sense of global citizenship, we can create a more peaceful and prosperous world.In conclusion, the future holds many challenges, but we, as the youth, have the potential to overcome them. By embracing lifelong learning, addressing social inequality, fighting climate change, and promoting tolerance, we can create a brighter future for ourselves and for generations to come.Let us not be afraid of change; instead, let us embrace it. Let us notbe daunted by the challenges ahead; instead, let us rise to the occasion. As the youth, we have the power to shape the world we want to live in. Together, we can make a difference.Thank you for your attention.。
青岛中考英语作文真题附两篇作文法国作家雨果曾说"进步,才是人应该有的现象”。
回首三年的初中时光，你在学习和生活种-定取得了不少的进步,比如学科知识生活技能、人际交往、体育锻炼、好习惯等方面。
请结合自身的身经历谈-谈自己的进步。
要求:1.选取至少两个面;2.结合自身身经历谈一谈过去与现在的不同;3.如何取得这些进步的;4.书写工整，语句通顺,连贯,词数不少于80。
注意:文中不得出现真实人名、校名地名及其他相关信息。
范文：（一）As French writer Victor Hugo once said, "progress is the phenomenon that humans should have." Looking back at my first three years in junior high school, I realized that I have made significant progress in various aspects of my life, such as academic knowledge, life skills, interpersonal communication, physical exercise, and good habits.Academically, I have improved my grades significantly, especially in subjects that I initially found challenging, like math and science. By studying hard and seeking help from my teachers and peers, I have developed a better understanding of these subjects and gained more confidence in my abilities.Outside of the classroom, I have also learned valuable life skills, such as cooking, cleaning, time management, and problem-solving, that have helped me become more independent and responsible. Additionally, through participating in various social activities and extracurricular clubs, I have improved my communication and teamwork skills and made many meaningful connections with my peers.In terms of physical exercise, I have started to engage in regular workouts and sports activities, which have not only improved my physical health but also boosted my mental and emotional well-being. And through cultivating good habits, such as reading regularly, practicing mindfulness, and striving for self-improvement, I have established a positive and constructive mindset, which has contributed significantly to my overall progress.All in all, looking back on these past few years, I feel proud of the progress I have made in various aspects of my life. I am grateful for the opportunities and challenges that have helped me grow and develop, and I am determined to continue on this path of progress and personal growth. After all, as Victor Hugo noted, progress is the phenomenon that humans should strive for.译文：正如法国作家维克多·雨果所说:“进步是人类应该有的现象。
The path to progress lies beneath our feet,and it is a journey that each of us must embark on to achieve personal growth and success.This path is not always smooth or easy,but it is a necessary one for those who aspire to reach their full potential.To begin with,the path of progress requires a strong foundation of knowledge and skills. Just as a builder needs a solid base to construct a house,we too must acquire the necessary tools and understanding to navigate our chosen fields.This often involves education and continuous learning,as well as the development of practical abilities that can be applied in various situations.Moreover,progress is often achieved through perseverance and determination.The road to success is rarely a straight one,and we may encounter obstacles and setbacks along the way.It is important to remain resilient and to keep pushing forward,even when the going gets tough.This requires a positive mindset and the belief that we can overcome challenges and achieve our goals.In addition,progress is closely linked to innovation and creativity.To move forward,we must be willing to think outside the box and to explore new ideas and approaches.This can involve taking risks and stepping out of our comfort zones,but it is often through these experiences that we learn the most and grow as individuals.Furthermore,progress is also about personal development and selfimprovement.This involves cultivating qualities such as empathy,integrity,and resilience,which can help us navigate the complexities of life and build meaningful relationships with others.It also means being open to feedback and willing to learn from our mistakes,as this can lead to greater selfawareness and personal growth.Finally,the path to progress is a lifelong journey that requires ongoing effort and commitment.It is not something that can be achieved overnight,but rather it is a process that unfolds over time as we continue to learn,adapt,and evolve.By staying focused on our goals and maintaining a growth mindset,we can continue to move forward and make progress in all areas of our lives.In conclusion,the path to progress is a multifaceted journey that involves acquiring knowledge,developing skills,persevering through challenges,embracing innovation,and focusing on personal growth.By taking these steps and remaining committed to our goals, we can unlock our full potential and achieve the success we desire.。
The path to progress is often likened to a mountain that one must climb.This metaphor is not just a figure of speech it encapsulates the essence of the journey towards selfimprovement and the realization of ones goals.Here are some key points that can be included in an essay on the theme of The Road to Progress Lies in the Ascent:1.Setting Goals:The first step in any journey is to set a clear destination.In the context of progress,this means identifying what one wishes to achieve,whether its personal growth,career advancement,or the mastery of a new skill.2.Overcoming Challenges:Just as a mountaineer must overcome physical obstacles, those seeking progress must face and overcome challenges.This could involve learning from failures,adapting to change,or pushing through moments of selfdoubt.3.Growth Mindset:Embracing a growth mindset is crucial for progress.This involves understanding that abilities and intelligence can be developed over time,rather than being fixed traits.4.Continuous Learning:The ascent is neverending because learning is a lifelong process. Continuously acquiring new knowledge and skills is essential to stay relevant and competitive in ones field.5.Resilience:The ability to bounce back from setbacks is a key characteristic of those who make progress.Resilience allows individuals to learn from their mistakes and keep moving forward.6.Discipline and Perseverance:Just as a climber must maintain focus and keep climbing, one must apply discipline and perseverance to their goals.This means staying committed to a plan and not giving up when the going gets tough.7.Support Systems:No climb is made alone.Similarly,having a support system of mentors,peers,and loved ones can provide encouragement and guidance along the path to progress.8.Celebrating Milestones:Recognizing and celebrating achievements along the way is important for maintaining motivation.Each milestone reached is a testament to the progress made and the effort put in.9.Adaptability:Just as climbers must adapt to changing weather conditions and terrain, individuals must be adaptable to changing circumstances in their pursuit of progress.10.Reflection and SelfAssessment:Regular reflection on ones journey is essential for selfimprovement.This involves assessing what has worked,what hasnt,and what changes need to be made to continue progressing.11.Innovation and Creativity:Just as finding new routes to the summit can be a part of mountain climbing,being innovative and creative in ones approach to problemsolving can lead to new opportunities and breakthroughs.12.Legacy and Impact:Finally,considering the legacy one wishes to leave and the impact one wants to have can provide a deeper sense of purpose and drive to continue the climb towards progress.In conclusion,the road to progress is indeed like a mountain to be climbed.It requires a combination of clear vision,determination,resilience,and the willingness to learn and adapt.By embracing these principles,one can navigate the challenges and enjoy the view from the summit of personal and professional growth.。
如何培养大学生爱国主义的英语作文四级Patriotism is a deep-rooted sentiment that inspires individuals to love and support their country. It is a vital component of a nation's identity and plays a crucial role in fostering a sense of unity, pride, and commitment among its citizens. As the future leaders and pillars of society, university students hold immense potential to shape the trajectory of a nation. Therefore, cultivating patriotism among university students is of paramount importance.One of the most effective ways to nurture patriotism among university students is through the integration of patriotic education into the curriculum. This can be achieved by incorporating courses or modules that delve into the history, culture, and achievements of the nation. By exposing students to the rich tapestry of their country's past, they can develop a deeper understanding and appreciation for the sacrifices and contributions made by their ancestors. Additionally, these courses can highlight the nation's contemporary successes and challenges, encouraging students to actively engage in discussions and debates that foster a sense of civic responsibility.Furthermore, university campuses can organize various extracurricular activities and events that celebrate national heritage and promote patriotic values. This could include cultural festivals, national day celebrations, and commemorative ceremonies that honor the nation's heroes and significant historical events. These events not only provide opportunities for students to immerse themselves in their country's traditions but also foster a sense of community and belonging among their peers. By actively participating in these activities, students can develop a stronger emotional connection to their homeland and a deeper commitment to its well-being.Another crucial aspect of cultivating patriotism among university students is the role of faculty and staff. Educators can serve as influential role models, inspiring students to embrace patriotic ideals through their own actions and teachings. By incorporating patriotic themes and perspectives into their lectures and discussions, faculty members can encourage students to critically analyze national issues and develop a nuanced understanding of their country's strengths and challenges. Additionally, university administrators can ensure that the institution's policies and practices align with patriotic principles, such as promoting national symbols, supporting community engagement, and fostering an environment that celebrates diversity and inclusivity.Moreover, universities can facilitate opportunities for students to engage in community service and volunteer initiatives that contribute to the betterment of their nation. These activities can range from environmental conservation projects to social welfare programs, allowing students to directly experience the impact they can have on their local communities and the country as a whole. By witnessing the tangible results of their efforts, students can develop a sense of pride and ownership in their nation's progress, further strengthening their patriotic sentiments.Another effective approach to cultivating patriotism among university students is through the integration of technology and digital platforms. Social media, for instance, can be leveraged to disseminate information about the nation's history, culture, and achievements, as well as to facilitate discussions and exchanges among students. Additionally, virtual tours and interactive digital exhibits can provide students with immersive experiences that deepen their understanding and appreciation of their country's heritage. By harnessing the power of technology, universities can create engaging and accessible platforms that resonate with the digital-savvy student population.It is also crucial to recognize that patriotism is not merely about blind loyalty or uncritical acceptance of the status quo. Instead, it should be fostered in a manner that encourages students to thinkcritically, question constructively, and actively participate in the democratic process. Universities can promote this by providing platforms for students to engage in respectful debates, express their views, and propose innovative solutions to national challenges. This approach not only cultivates patriotism but also nurtures the development of well-rounded, engaged citizens who are committed to the betterment of their country.Furthermore, universities can collaborate with various stakeholders, such as government agencies, non-profit organizations, and community leaders, to develop comprehensive programs and initiatives that cater to the unique needs and interests of their student population. By leveraging these partnerships, universities can create tailored experiences that resonate with students and inspire them to become active participants in the nation-building process.In conclusion, cultivating patriotism among university students is a multifaceted endeavor that requires a holistic and inclusive approach. By integrating patriotic education into the curriculum, organizing engaging extracurricular activities, empowering faculty and staff as role models, facilitating community service opportunities, leveraging digital platforms, and fostering critical thinking and civic engagement, universities can play a pivotal role in shaping the next generation of patriotic citizens. Through these concerted efforts, universities can contribute to the development of a strong, united,and progressive nation that is poised to face the challenges of the future with confidence and determination.。
关于学生进步的英语作文Student progress is a multifaceted and complex topic that encompasses various aspects of an individual's academic, personal, and social development. It is a journey that involves overcoming challenges, embracing new opportunities, and continuously striving for improvement. In this essay, we will delve into the different dimensions of student progress and explore the factors that contribute to their overall growth and success.One of the primary indicators of student progress is academic performance. Students are constantly challenged to expand their knowledge, hone their critical thinking skills, and demonstrate their understanding through various assessments and assignments. As they navigate the educational landscape, they encounter new subjects, concepts, and learning methodologies, each presenting its own set of obstacles. However, the ability to overcome these hurdles and achieve academic milestones is a testament to a student's dedication, resilience, and intellectual capacity.Alongside academic progress, student growth also encompassespersonal development. This includes the cultivation of essential life skills such as time management, problem-solving, communication, and emotional intelligence. As students navigate the complexities of their academic lives, they are also tasked with managing their own well-being, maintaining a healthy work-life balance, and developing strategies to cope with stress and challenges. The ability to navigate these personal challenges and emerge as more self-aware, adaptable, and resilient individuals is a significant aspect of student progress.Furthermore, student progress is often measured by their social and interpersonal development. The educational environment provides ample opportunities for students to engage in collaborative learning, participate in extracurricular activities, and build meaningful relationships with their peers and mentors. Through these experiences, students learn to navigate social dynamics, develop empathy, and cultivate essential communication and teamwork skills. These social and interpersonal skills not only contribute to a student's academic success but also prepare them for the demands of the professional world and their future endeavors.Another crucial component of student progress is the development of leadership and decision-making abilities. As students progress through their educational journey, they are often presented with opportunities to take on leadership roles, whether it be in student government, club organizations, or community-based initiatives.These experiences allow students to hone their decision-making skills, learn to delegate responsibilities, and develop the confidence to inspire and guide their peers. The ability to effectively lead and make informed decisions is a valuable asset that will serve students well in their future pursuits.Technological proficiency is also a significant aspect of student progress in the modern educational landscape. As technology continues to permeate every aspect of our lives, students must acquire the skills and knowledge to navigate digital platforms, utilize various software and applications, and adapt to the ever-evolving technological landscape. The ability to leverage technology not only enhances a student's academic performance but also prepares them for the demands of the 21st-century workforce.Finally, student progress is often measured by their growth in terms of cultural awareness, global citizenship, and a sense of social responsibility. As the world becomes increasingly interconnected, students are exposed to diverse perspectives, cultures, and societal issues. The ability to develop a deeper understanding and appreciation for this diversity, as well as a commitment to making a positive impact on local and global communities, is a crucial component of student progress.In conclusion, student progress is a multifaceted and dynamicprocess that encompasses academic, personal, social, leadership, technological, and cultural dimensions. Each aspect of student progress is equally important and contributes to the holistic development of the individual. By recognizing and fostering these various aspects of progress, educational institutions, parents, and students themselves can work together to create an environment that nurtures growth, empowers individuals, and prepares them for the challenges and opportunities that lie ahead.。
世界在进步作文英语Title: Progress in the World。
In today's rapidly changing world, progress is evident in various aspects of human life, from technological advancements to social reforms. The journey of progress is marked by innovation, adaptation, and the collectiveefforts of individuals and societies. Let's delve into some key areas where progress is prominently observed.Technological Advancements:One of the most apparent signs of progress is seen in the realm of technology. Breakthroughs in fields like artificial intelligence, biotechnology, and renewable energy have revolutionized how we live and work. For instance, AI has enabled automation in various industries, streamlining processes and increasing efficiency. Biotechnology has facilitated significant advancements in healthcare, leading to the development of vaccines, genetherapies, and personalized medicine. Moreover, the shift towards renewable energy sources like solar and wind power signifies progress in combating climate change andpromoting sustainability.Economic Development:Another crucial aspect of progress is economic development. Across the globe, we witness countriesstriving to improve their economies through innovation, trade, and investment. Emerging markets are experiencing rapid growth, lifting millions out of poverty and enhancing living standards. Furthermore, initiatives likemicrofinance and social entrepreneurship are empowering marginalized communities and fostering inclusive economic growth. However, challenges such as income inequality and unemployment persist, underscoring the need for equitable economic policies and opportunities for all.Social Reforms:Progress is also evident in the realm of social reforms,where societies are striving for greater equality, justice, and inclusivity. Movements advocating for gender equality, LGBTQ+ rights, and racial justice have gained momentum, leading to policy changes and cultural shifts. Additionally, advancements in education and healthcare have contributedto improved quality of life and expanded opportunities for individuals worldwide. However, social progress is an ongoing journey, requiring continuous dialogue, activism, and policy interventions to address systemic inequalities and injustices.Environmental Conservation:In recent years, there has been a growing recognitionof the importance of environmental conservation inachieving sustainable progress. Efforts to preserve biodiversity, reduce pollution, and mitigate climate change have gained traction globally. Governments, businesses, and civil society are increasingly adopting eco-friendly practices and investing in renewable technologies.Initiatives like reforestation, waste management, and conservation efforts aim to protect natural ecosystems andensure a habitable planet for future generations. Nonetheless, the urgency of environmental challenges calls for concerted action and international cooperation.Cultural Exchange and Understanding:Progress is not merely confined to material advancements but also encompasses cultural exchange and understanding. In an interconnected world, people from diverse backgrounds interact more than ever, fostering cross-cultural dialogue and appreciation. The exchange of ideas, languages, and traditions enriches societies and promotes mutual respect and understanding. Moreover, advancements in communication technology have facilitated instant connections across borders, transcending geographical barriers and fostering a sense of global community.In conclusion, the world is undeniably progressing in various spheres, driven by innovation, collaboration, and a shared aspiration for a better future. While challenges and disparities persist, the collective efforts of individuals,communities, and institutions are steering us towards a more inclusive, sustainable, and prosperous world. As we navigate the complexities of the modern era, let us remain committed to the ideals of progress, ensuring that it benefits all of humanity.。
In todays rapidly evolving world,the exchange of ideas and perspectives is crucial for the development of individuals,communities,and nations.It is through the sharing and discussion of diverse viewpoints that we can foster innovation,promote understanding,and drive progress.Firstly,the exchange of ideas is the cornerstone of innovation.When people from different backgrounds and disciplines come together to share their thoughts and experiences,it can lead to the creation of new ideas and solutions.For example, interdisciplinary research often results in groundbreaking discoveries,as the combination of different perspectives can lead to novel approaches to problemsolving.Secondly,the sharing of viewpoints is essential for promoting understanding and tolerance among people.In our increasingly globalized world,it is important to recognize and respect the diversity of cultures,beliefs,and values.By engaging in open and respectful dialogue,we can learn from one another and appreciate the richness of our differences.This can help to break down barriers,reduce misunderstandings,and foster a sense of unity and cooperation.Moreover,the exchange of ideas is vital for the development of individuals.As we encounter new perspectives and challenge our own beliefs,we are forced to think critically and expand our horizons.This process of intellectual growth can lead to increased selfawareness,improved decisionmaking skills,and a greater sense of empathy and compassion for others.Furthermore,the sharing of viewpoints can also contribute to the development of communities and societies.When people come together to discuss and debate important issues,it can lead to the identification of common goals and the formulation of effective strategies for addressing challenges.This collaborative approach can help to build stronger,more resilient communities that are better equipped to navigate the complexities of the modern world.However,the exchange of ideas is not without its challenges.It requires a willingness to listen and engage with others,even when their views may differ from our own.It also necessitates the development of effective communication skills and the ability to articulate ones thoughts and opinions clearly and respectfully.In conclusion,the exchange of ideas and perspectives is a vital component of personal, community,and societal development.By fostering an environment where diverse viewpoints can be shared and discussed,we can unlock the potential for innovation,understanding,and progress.It is our collective responsibility to embrace this process and work together to create a more enlightened and inclusive world.。
The pursuit of progress is a journey without end,a continuous voyage of selfimprovement and growth.It is a path that every individual embarks upon,driven by the innate desire to learn,adapt,and excel in various aspects of life.From the moment we are born,we are on a relentless quest for knowledge and understanding.As children,we learn to walk,talk,and interact with the world around us. We explore,ask questions,and seek answers,gradually building a foundation of skills and knowledge that will serve us throughout our lives.As we grow older,our definition of progress evolves.We may strive for academic excellence,professional success,or personal fulfillment.We set goals,work hard,and push ourselves to achieve more,always with the understanding that there is always room for improvement.In the realm of education,progress is measured by the acquisition of knowledge and the development of critical thinking skills.Students are encouraged to challenge themselves, to think creatively,and to solve problems in innovative ways.The pursuit of academic progress is a lifelong endeavor,as learning never truly ends.In the workplace,progress is often tied to career advancement and professional development.Employees are expected to continuously improve their skills,to stay current with industry trends,and to contribute positively to the growth of their organizations.The pursuit of professional progress requires dedication,adaptability,and a willingness to embrace change.In our personal lives,progress can take many forms.It may be the pursuit of physical fitness,the cultivation of meaningful relationships,or the development of personal hobbies and interests.The pursuit of personal progress is a deeply individual journey, shaped by our unique values,passions,and aspirations.The path of progress is not always smooth or straightforward.It is marked by challenges, setbacks,and moments of doubt.However,it is through these experiences that we learn the most valuable lessons.We learn resilience,perseverance,and the importance of selfreflection.In conclusion,the pursuit of progress is an ongoing journey that shapes our lives in profound ways.It is a testament to our capacity for growth,our desire for selfimprovement,and our unwavering commitment to learning and evolving.As we navigate this path,we must remember that progress is not a destination,but a continuous process of discovery,exploration,and transformation.。
关于小组任务的英语作文Title: Group Tasks: Enhancing Collaboration and Achieving Success。
Introduction:Group tasks are an integral part of academic, professional, and personal life. They require individuals to work together, combining their skills, knowledge, and efforts to accomplish a shared objective. This essay aims to explore the significance of group tasks, the challenges they present, and effective strategies to overcome them, ultimately leading to successful outcomes.Body:1. Importance of Group Tasks:Group tasks foster collaboration, communication, and teamwork. They provide an opportunity for individuals tolearn from one another, share ideas, and develop essential interpersonal skills. Moreover, group tasks encourage the division of labor, allowing each member to contribute their unique strengths and expertise. By working together, groups can accomplish more than individuals working alone, leading to enhanced creativity, efficiency, and overall success.2. Challenges in Group Tasks:Despite the numerous benefits, group tasks can be challenging due to various reasons:a) Communication barriers: Differences in communication styles, language proficiency, or shyness can hinder effective information exchange and understanding among group members.b) Conflicting opinions: Divergent viewpoints and personal biases may lead to disagreements, making it difficult to reach a consensus and hindering progress.c) Unequal contribution: Some members may contributeless or fail to fulfill their assigned tasks, causing frustration and imbalance within the group.d) Time management: Coordinating schedules, meeting deadlines, and ensuring everyone's availability can be challenging, especially when group members have conflicting commitments.3. Strategies for Successful Group Tasks:To overcome the challenges and ensure successful outcomes, the following strategies can be employed:a) Establish clear goals and roles: Define theobjective of the task and assign specific responsibilities to each member based on their strengths and interests. This will promote accountability and ensure everyone knows their role in achieving the common goal.b) Effective communication: Encourage open and respectful communication among group members. Active listening, clarifying doubts, and providing constructivefeedback can enhance understanding and reduce conflicts.c) Regular progress checks: Schedule regular meetings to track progress, discuss challenges, and brainstorm solutions. This will help identify any issues early on and allow for timely adjustments.d) Encourage equal participation: Promote an inclusive environment where every member feels valued and encouraged to contribute. Encourage quieter members to express their ideas and ensure that tasks are distributed equitably.e) Time management: Set realistic deadlines and create a shared schedule to ensure everyone is aware of upcoming milestones. Encourage members to manage their time effectively and communicate any conflicts well in advance.Conclusion:Group tasks provide an excellent opportunity for individuals to collaborate, learn from one another, and achieve shared goals. While challenges may arise, employingeffective strategies can help overcome them and ensure successful outcomes. By fostering effective communication, equal participation, and proper time management, groups can harness their collective potential and achieve remarkable results. Embracing the collaborative nature of group tasks will not only enhance personal growth but also contribute to a more productive and harmonious society.。
Extended Summary本文は pp.1031-1043－2－Progress, Understanding and Challenges in the Field of NanodielectricsMichel F. Fréchette Non-member (IREQ) Clive W. Reed Non-member (Consultant) Howard Sedding Non-member (Kinetrics Inc.)Keywords : nanodielectrics, nanomaterials, polymer nanocomposites, inorganic/polymer nanocomposites, insulating materials, dielectricsThe field of nanotechnology has emerged as one of the mostactive technological areas worldwide, and interest in nanodielectrics has grown rapidly as a potential new generation of HV insulating materials with unique properties. Experimental progress in this field and the challenges facing practical implementation needed to be commented. A wide range of materials (largely nanofillers in a polymer matrix or intercalated or exfoliated layered natural or synthetic inorganics within a polymer matrix) are being evaluated by universities and industry, and several significant improvements in important electrical, mechanical, physical, and thermal properties confirmed. This suggests that a number of HV insulation applications could benefit from such materials. However, some limitations have been identified which need to be understood and corrected or accom- modated, e.g. the role of the nano-inorganic-polymer interface. When the concept of nanodielectrics was introduced in 2001, it emerged in the middle of several developing activities associated with nanotechnology. After some 5 years, it turns out that the nanotechnological effort has been increased and widened. This is easily illustrated by considering the blooming of the number of conferences and meetings dealing with nanotechnological aspects. Although no outstanding and revolutionary commercial success has been confirmed over this period, investments have continued to flow into nanotechnology research and development, which is somewhat surprising. It is maybe because science is at a turning point. For a long while, science has forced to explore in the limits of the largest and the smallest, with a will to push beyond. But it is no more the ultimate. Along the years has emerged the realization that lateral levels (at some dimensions) of interest lied along the paths, some science was there to be discovered, and it corresponded to a wealth of numerous social-economic benefiting applications.For nanostructured materials, some breakthroughs were produced, in particular in reference to nanocomposites and multifunctional thin-films. It is suspected that many developments and findings are kept confidential, but some major steps were realized over the period, specially in seeking properties that do not obey the laws associated with the bulk behaviour.The story is only beginning so why then the present type of exercise? Indeed, the rise of interest if not its shift was so quick, it produced a non-negligible amount of data in a very short period of time. From there, risks are emerging too and there is still much magic surrounding the field. At least two elements were stressed in regard of these points. Measurements and properties were found to depend greatly on the material synthesis particularities and reproducibility and phenomenology are very much sensitive to recipes and quality of the end-products. If there is magic it is very much varying with content and morphology, and there is a serious need for quality control of the developed materials.Figure 1 offered an interesting insight in the field. Though not based on a extremely precise analysis, it illustrated clearly two developing streamlines. Nanofiller must be added to microcomposites if one wants to obtain solid dielectrics with electrotechnical superior performance as compared to conventionnally-filled polymeric matrix. This does not discard research activities dealing exclusively with nanofillers. Those are necessary for more fundamental understanding and yet they may be an alternative pushing for the adoption of thermoplastics in replacement of thermosets in an environmental context.Some discussion made explicit our lack of sufficient understanding about the situation. The conclusion is that we ignore more than we know, and this state-of-situation usually prevents a clear and direct access to applications. Though it is always hoped from a new discovery or concept, that it will bring uniqueness, thus new solutions leading to extraordinary gains as opposed to incremental ones, some discussion pointed out at some dual or two-fold phenomenologies that make think that there is underground or hidden potential to be realized.Nonetheless, HV electrotechnical applications were envisaged. An instant snapshot based on the emerging data was put forward. It is essential nowadays to question right away how the outcome of research could fit in and benefit the applications. Even now, the conclusion is that these new findings could find its way to very practical problems, add-ons, etc. However, it is much too early to estimate profitability. But, some needs for developments were formulated.Finally, the limited survey indicates that there is a strong need for quality control of the “nanodielectrics” and accrued documented knowledge linking the nanostructural morphologyand the macroscopic observables.Fig. 1. Schematic histogram of the variation of breakdown strength and the surface corona resistance of solid insulating materials containing different fillers; NC stands for nanocomposite and MC, for microcomposite; The relative magnitude is set at 1 for microcomposites and the vertical arrows give an indication of the varianceProgress, Understanding and Challenges in the Field of NanodielectricsMichel F. Fréchette*Non-memberClive W. Reed**Non-memberHoward Sedding***Non-memberThe field of nanotechnology has emerged as one of the most active technological areas worldwide, and interest in nanodielectrics has grown rapidly as a potential new generation of HV insulating materials with unique properties. Experimental progress in this field and the challenges facing practical implementation will be commented. A wide range of materials (largely nanofillers in a polymer matrix or intercalated or exfoliated layered natural or synthetic inorganics within a polymer matrix) are being evaluated by universities and industry, and several significant improvements in important electrical, mechanical, physical, and thermal properties were confirmed. This suggests that a number of HV insulation applications could benefit from such materials. However, some limitations have been identified which need to be understood and corrected or accommodated. The role of the nano-inorganic-polymer interface (dielectric and electronic properties, space charge mitigation, band-gap and charge injection effects, and morphology effects) will be considered. Based on this analysis, the ultimate potential that might be realized via nanodielectrics will be envisaged.Keywords : nanodielectrics, nanomaterials, polymer nanocomposites, inorganic/polymer nanocomposites, insulating materials, dielectrics1. A Brief PerspectiveWhen the concept of nanodielectrics was introduced in 2001(1), it emerged in the middle of many developing activities associated with nanotechnology. After some 5 years, it turns out that the nanotechnological effort has been increased and widened. This is easily illustrated by considering the blooming of the number of conferences and meetings dealing with nanotechnological aspects(2). It is noteworthy that some past existing items have been adapted to a new flavour. It is also necessary to recall, as pointed out twice earlier(1)(3), that some past observations and phenomenologies had to do with a nanometric scale but then there was no focus as today with nanotechnology. Again, there are a spectrum of effects that goes with intervening at the nanometric scale. Sometimes, it brings a small positive increment on a property; in others, it elicits new phenomenologies.Although no outstanding and revolutionary commercial success has been confirmed over this period, investments have continued to flow into nanotechnology research and development, which is somewhat surprising. It is maybe because science is at a turning point. For a long while, science has forced to explore in the limits of the largest and the smallest, with a will to push beyond. But it is no more the ultimate. Along the years has emerged the realization that lateral levels (at some dimensions) of interest lied along the paths, some science was there to be discovered, and it corresponded to a wealth of numerous social-economic benefiting applications.Still now the progress in the area of nanotechnology can be followed along 3 rather well delineated streamlines: operations at nanoscale, molecular machines and approach to fabrication, and molecularly tailored materials. For nanostructured materials, some breakthroughs were produced, in particular in reference to nanocomposites and multifunctional thin-films(4). It is suspected that many developments and findings are kept confidential, but some major steps were realized over the period, specially in seeking properties that do not obey the laws associated with the bulk behaviour.Efforts have continued to elicit great progress relatively to superplasticity and ductility of superstrong nanomaterials. The mechanical properties of nanocrystalline materials often exhibit super strength, superhardeness and enhanced tribological characteristics, but at the moment(5), focus is on obtaining in addition a substantial ductility and superplasticity. That would be a unique combination.Developments have accrued relative to magnetic effects. Efforts were devoted now to incorporate supermagnetic and ferromagnetic behaviours to polymer nanocomposites(6).Many strategies are unfolding to resolve the limit imposed by the brittleness of nanocrystalline ceramics. For this, reinforced second phases are used to develop nanometric-scale composite materials. Due to the extraordinary properties of carbon nanotubes, these are considered as incorporation to ceramics (to metals and polymers too). However, the potential of this action has not yet been successfully demonstrated(7). Besides, much effort will have to be deployed to obtain and ascertain high purity single wall carbon nanotubes(8). Much interest stays with the unfolding and understanding of grain boundaries characteristics(9). There is also a great potential to be realized via POSS (Polyhedral Oligomeric Silsesquioxane) chemical technology that elicits tailoring property of a solid between those of a polymer and ceramics(10). But, nano-filled polymer ceramic composites have acknowledged application potential in microsystem technology(11).For the field of nanodielectrics and their applications, the area of polymer nanocomposites remains the driving stemming inspiration and the provider of the materials and their* Institut de Recherche d’Hydro-QuébecVarennes, Québec, Canada** ConsultantNew York, 12302 USA*** Kinetrics Inc.KL204電学論A，126巻11号，2006年 1031characterization. To this effect, we note the continued effort invested in the organization of the Polymer Nanocomposites Symposia(12) and the emergence of the first symposium on nanostructured and functional polymer-based materials and nanocomposites(13). Table 1 illustrates some developments involving a polymeric matrix containing added nanostructures. References (14) to (20) were consulted in building the table. The thermoplastics consumption in the world has stayed dominant (over thermosets) and it reflects in the development and adoption of nanocomposites(21). Automotive and food packaging applications are driving the market while there is a lot of material functionalizing. Some other applications of importance considered are: gas barrier, oxygen barrier, fuel tanks, films, environment protection and flammability reduction.A considerable amount of data on nanodielectrics suddenly appeared in the recent years marking some progress. While there appears to be some very promising results to-date, there are also many results, though interesting, which are disappointing. The application of nanodielectrics to electronics and photonics is well established, but not so to HV insulation such as used in generators, motors, transformers, cables, capacitors, bushing, HV supplies, or as insulation in a multitude of aerospace and military applications. In fact, however, fillers (of fumed or colloidal or other specialized origin), on the nanometric scale, have been used for as long as 30 to 40 years, in limited applications, though nonetheless, very successfully. As with many antioxidants, voltage stabilizers, stress-grading additives, or similar molecular-scale additives, generally the use of “nanodielectrics” has been highly proprietary, since their use has been instrumental in superior insulation performance or processing or overall cost advantage or some other desirable property.For the moment, nanodielectrics deal mainly with a matrix containing added nanostructures. In that sense, it recalls very strongly earlier work and achievements relative to reinforcements and fillers. Properties of polymers were found to be significantly improved by adding solid particles to the thermoplastic resins. It is a well established field and some recipes are well known. The work of Cherney may certainly be offered as a reference(22). Some features of the situation must be recognized. A diversity of properties can be affected, and sometimes more than one at a time are changed. The dimension of the added reinforcement and filler ranges in the micrometric size to submicrons. Also, it is usual that the filler may reach 10 to 40 % of the compound weight. Is the knowledge acquired for this micrometric situation be transposed when the nanometric scale is involved? It is very tempting, yet it is not so, at least to a large extent.Such a high-content of the filler, many times an inorganic, may bring about extra cost and extra weight. The question here is “Can these issues be addressed by replacing high content by high specific area associated with the nanoparticles ?” It turns out that nanoparticles with high aspect ratios have proven to be good reinforcing agents in polymeric materials. Among all nanoparticle reinforced composites, the most widely investigated systems are based on silicates and clay particles(23).When dealing with the nanoparticles, many additional and dominant parameters come into play. Filler size, shape, and the homogeneity of the particle distribution become critical parameters, with an accrued importance on filler/matrix interface coupling nature and quality. The nature of the interface will be affected to a great extent by the chemical synthesis routeTable 1. Examples of a polymer matrix containing nanostructuresMATRIX NANO-FILLER PROPERTIES / FIELD / APPLICATIONPV AlPoly(vinylalcohol)Carbon nanotube Thermomechanical and electrical properties, Functionalized; taken from Ref. (14)PVC Cellulose whiskers Mechanical performanceFunctionalized; taken from Ref. (14)Thermoplastic Olefin Modified nanoclays withAl, Si, HydroxylsLow mass, cost effective, improved surface qualityAutomotive molded body partsCommercialized on car; taken from Ref. (15)Polypropylene Carbon nanotube (CNT)Nanoclay (NC) All things being equal, smaller fillers achieve the required stiffness at lower filler concentrations Less weight % CNT than NC; taken from Ref. (16)PET Intercalatedclay PolycondensationFunctionalized; taken from Ref. (14)Polyamide, e.g. PA-6 Exfoliated silicates1-3 vol %70 % higher tensile modulus130 % higher flexural modulus50 % lower oxygen permeationCommercially important for automotive, aerospace, food packaging; from Ref. (14)Rubber Carbon black Strength, elasticity and abrasionStructural engineering; taken from Ref. (17)Epoxy Silicatelayers(Synthetic,1-nm thick with highaspect ratio of 200) Matrices for carbon or aromatic fibers reinforces composites used in aerospace industry High modulus and high temperature performanceTaken from Ref. (18)Epoxy TiO2200-400 nm Best improvements on stiffness, impact strength and wear resistance at a content of 4 vol %. Taken from Ref. (19)Nylon-6 SiO2Pre-treated Rigidity and toughness improved at an optimal content of 4.3 wt %Higher dynamic viscositiesSuperior storage moduli at HFTaken from Ref. (20)1032 IEEJ Trans. FM, Vol. 126, No.11, 2006Progress Relative to Nanodielectrics電学論A ，126巻11号，2006年 1033employed to produce the nanocomposite and how the nanoparticles were fabricated, pre-treated (19), and compatibilized. The driving knowledge relevant to the situation involving nanometric-scale particles is closer to what was acquired from developing and dealing with special additives (24)(25) for electrotechnical and non-electrotechnical applications and from compounding polymer blends (26)(27). Table 2 offers a comparison between a typical case involving nanoclay and conventional filler. Much of the information was taken from the literature (14)(28).Profitability of going “nano” cannot be generalized. Yes, there are some trend principles, e.g. high aspect ratios bring about significant property enhancement, smallness of the filler ensures less surface distortion, lower amount of filler minimizes density. For the rest, each business case must show merit. For instance, in the automotive industry, reduction of weight is very important (15). This annotated appreciation will be developed along several streamlines pinpointing at some drawbacks and weaknesses of the newly emerging dielectric materials. Impact on the electrical insulation arena will be also discussed with identification of some required developments and needing achievements.2. What Do We Know about Nanodielectrics ?Generally, nanodielectrics might encompass all solid materials where one dielectric material is incorporated inside another and has one dimension in the nanometric range (from 1 to 100 nm). It might include spherical, ellipsoid-shaped particles, rod-shaped particles (e.g. nanotubes), monolayers, thin layers, or larger layered particles (such as natural or synthetic clays) where the layers have been penetrated by a second dielectric phase (intercalation) or even fully separated (exfoliation). Largely, however, much of the work to date on nanodielectrics has focused on spherical particles (typically oxides) made by, for example, a fuming process, or intercalated or exfoliated natural or synthetic clays (e.g. montmorillonite). Very closely related, however, are some block copolymers and some polymer blends, where one of the blocks or polymers is of nanometric size and the resulting qualities are highly synergistic. For example, polyurethanes made with nano-sized rigid polymer blocks, can achieve remarkable mechanical properties, and where used in demanding electrical applications, excellent superior insulating qualities.Chemistry and processing play a controlling hand in many ofthe qualities published during the work on nanodielectrics over the past five years. Functionalization, compatibilization, and the use of coupling agents are already emerging as big players, though significantly few details have been provided; possibly as a result of lack of such information from the supplier to the investigator or the conscious proprietary exclusion of such information. In the work of the past five years, improvements in properties such as breakdown, electrical endurance, permittivity, space charge behaviour and other electrical properties, mechanical properties, thermal conductivity, some thermal endurance qualities, and processability, have been identified in some nanodielectic structures. Though not all, and sometimes adverse effects have been noted. Sometimes, the benefits were not substantial, and long term performance has been relatively little investigated.A lot of the information on nanodielectrics and their electrical properties and behaviours come from what was reported at the annual conferences on electrical insulation and dielectric phenomena since 2001. The discussion here includes other more limited data. In general, after scrutinizing the “nanodielectric” literature, one must conclude that experimentation is carried out with non-optimized sample materials. Also, there is deficiency in the details given about their synthesis and/or about characteristics of their resulting microstructures. This precludes, to our opinion, many definite and definitive conclusions on the topic. This may also blur generalized trends.Some works present a comparative study involving a polymeric solid and a composite consisting of the same polymer matrix with nano-fillers. This is misleading sometimes, i.e. the benefit does not necessarily come from the nanometric dimension of the filling particle. It is already known that fillers added to a polymeric matrix will improve one or several of its properties. However, the main contribution of these studies is to show if some property is affected at very low content of the filler, and how this property evolves with varying the % content.Sometimes the breakdown strength is observed to be independent of the nanofiller content, as was found for a system of polyamide with up to 5 % wt. of mica (29) or for EV A (Poly(ethylene-co-vinyl acetate)) with 6 % wt. of organophilic silicates (30). However, many other systems exhibit an improvement at very low nanofiller content. For instance, an increase of this type was observed for a matrix of low-density polyethylene with MgO filler (31), for a matrix of polypropylene with nanoclays (32), a matrix of polyethylene with fumed SiO 2(33), a matrix of LDPE with layered silicates (5 % wt.)(34), and for a matrix of polypropylene containing organophilic silicates (30). Overall, the increase is usually steep, it occurs at low concentration (about 2 % wt.), it may reach as much as 20 to 60 % more (with respect to base matrix), and it levels off between 2 to 5 % wt. However, the breakdown strength is sensitive to the formulation and to the relation of the nanostructure with the matrix, as suggested by the results reported by Vaughan (35). Decrease in breakdown strength was observed for a formulation consisting of polyethylene and intercalated nanoclays (5 %).When dielectric properties of the polymer nanocomposites are studied, it is seldom the case that other properties are investigated at the same time. Thus, it precludes the assessment of the material performance with respect to a matrix form of prerequisites, unless the same synthesis and chemical route are used to prepare the samples to be studied. Except for some cases, e.g. (36)-(38), oneTable 2. Comparing characteristics of composites with different-scale fillers CONVENTIONAL FILLERNANOCLAY FILLERSize : 1 µmCste* volume # : 1 particle Surface or coupling agents Aspect ratio < 10 Loading > 20 %Dimensions : 1x100x100 µm Surface area 0.7 m 2/g Source : Mineral, syntheticStructure: Crystalline, amorphous Ex: TiO 2, Al 2O 3, SiO 2, ZnO Availibility : yes Cost lowerDrawback: less performing *cste = constantSize : 1 nmCste volume # : 106 particles Chemical modification of layers Aspect ratio 50 - 500 Loading 2 - 10 % Size 1x100x100 nm Surface area 600 - 700 m 2/g Source : Natural, syntheticStructure : layeredEx : Montmorillonite most usual Availibility: yes Cost higherDrawback : dispersion sensitive compatibilizeror 2 other properties are sometimes examined along the study of dielectric properties, e.g. glass transition temperature, Young modulus, degree of crystallinity, impact strength, thermal conductivity, thermal expansion, etc. However, there is a diversity of dielectric aspects which were examined, and often, a single study would address many of these aspects: observations on electrical treeing, dielectric spectroscopy (permittivity and losses), photoluminescence measurements, surface tracking and erosion, space charge measurements, breakdown, conduction and polarization/depolarization processes, volume resistivity, etc.Of those, surface degradation and electrical treeing in presence of corona were maybe the first and most important concerns to be dealt with. Earlier study of Henk(39) and following work(40)-(43) have revealed a substantial positive effect (easily from 2 times to more than 7) from filling a polymer matrix with nanofiller. Based on known phenomenologies linked with the presence of micrometric-size filler in insulating matrices, some peculiar observations were noticed when these measurements were carried out using nanometer-size filler. Using dielectric spectroscopy, one can conclude that different matrix materials with the same nano-fillers behave differently in their permittivity and losses(44). In epoxy nanocomposites, both the interfacial polarization anddipolar relaxation contributions can be clearly seen and polarization is also enhanced by increasing the loading of fillers. In polyethylene nanocomposites, interfacial polarization also can be observed, but spectrally it does not change its position and intensity with increasing temperature. It was found also that the losses at very low frequency is highly dependent on the initial functionalization of nanoparticles(33). Imai et al.(45) observed that the permittivity and tan δ decreased when base epoxy was transformed to nanocomposite epoxy. Dielectric properties of epoxy nanocomposites containing TiO2 and ZnO fillers were studied by Fothergill et al.(46), and they found that the dielectric spectroscopy results showed very little dependence upon the particle material, only the size appeared to be important. These results were considered to support that the dielectric properties of such nano-filled composites were controlled by Stern-Gouy-Chap- man layers around the particles.The behaviour of some polymer nanocomposites in relation to space charge were investigated. Overall, from these studies, e.g.(47)-(48), there seems to be a trend emerging. Space charge inception field decreases as compared to that of the base material. When a nanocomposite is involved, space charge was found to increase at low field and to decrease at high field(47). It was observed that some space charge behaviour was directly linked and was responding to chemical impurities associated with the compatibilization of the nanosilicates, and varied sensibly with the purification procedures(49). In the authors’ view, results from dielectric spectroscopy would be correspondingly affected. Pre-treatment of the nanoparticles is too a strong parameter in determining the outcome performance(50)(51).But the ultimate test, some sort of technological appraisal, is the performance of the nanocomposites comparative to that exhibited by a microcomposite, that is a polymer matrix containing a micrometer-size filler. Figure 1 presents the emerging trend relative to breakdown strength and surface corona resistance. It is meant to be illustrative as it includes several different study parameters. Here the comparison is intended to be with a conventional-filled matrix, e.g. epoxy with 55-65 % wt. of silica. Nelson et al. have shown that for a similar, yet low weight % (5 %), the breakdown strength of the nanocomposite exceeded greatly that of the microcomposite(52). Here a series of studies was consulted to establish a phenomenological trend for the electrical breakdown(52)-(54) and for the corona resistance(43)(53)-(58). In this exercise, some data were weighted somewhat intuitively.In both cases, the use of low-content nanofiller may give an approximative equal performance as compared to conventionally-filled matrices. But the real advantage comes with the use of both nano and micro fillers at the same time. This advantage can be felt much more in the property of corona resistance of surfaces, where more than doubling the resistance is observed in a system of epoxy + quartz + nanoclay(55). Although the understanding of the chemical route in preparing these nanocomposites and imaging of the nanostructures indicate that the nanoclay reinforced the resin where the microsize filler was not present, and in these regions, special bonding is privileged dueto a large surface ratio, other speculative details provide complimentary explanations and paths for further reflections(59). Some concepts were advanced and formulated to explain someof the phenomenology surrounding the polymer nanocomposites and their performance. The interfaces(60)(61) and interaction zones(51)(62)-(63) are certainly keys to understanding, yet the effectsof the chemical route for synthesis and changes in morphology are too lightly neglected. To put a little bit of nano in the matrix still sounds like adding some magic powder with a waive of the hand. The real question is “Are we adding more defects than the material can handle ?”In the flurry of activity over the past five years, a wide spectrumof materials and details of preparation have been studied and a wide spectrum of behaviour has been reported, ranging from significant improvements in dielectric (and other) properties, to modest improvements or even worse. Given the variations examined to-date, it is not unsurprising that our understanding of their causes and of the behaviours observed, is rather limited. To advance the cause of nanodielectrics, it will be important to separate and understand the individual roles of the nanoparticle and surrounding polymer matrix, and the interactions and synergistic effects between them.Fig. 1. Schematic histogram of the variation of breakdownstrength and the surface corona resistance of solid insulatingmaterials containing different fillers; NC stands fornanocomposite and MC, for microcomposite; The relativemagnitude is set at 1 for microcomposites and the verticalarrows give an indication of the variance1034 IEEJ Trans. FM, Vol. 126, No.11, 2006。
