Uniformization of silica particles by theory directed rate-zonal

Uniformization of silica particles by theory directed rate-zonal

centrifugation Can Hu,Yi Chen Key Lab of Analytical 260nm silica particles.

High quality photonic crystals were assembled with uniformed silica particles.

a r t i c l e i n f o Article history:

Received 7November 2014

Received in revised form 2February 2015Accepted 12February 2015

Available online 21February 2015Keywords:

Particle uniformization

Density gradient centrifugation Theoretical guidance Photonic crystal

a b s t r a c t

Non-uniform size distribution can be observed in the synthesis of nanoparticles.There is thus a compelling need for post-synthesis separation of nanoparticles.Herein,a theory directed rate-zonal cen-trifugation method was proposed to unify the as-synthesized silica spheres.A formula that quantitatively links the centrifugal time with centrifugal conditions was derived.Under the guidance of the formula,various silica particles with size from 80nm up to 5l m were successfully uniformed and/or separated in ca .1min by centrifugation.The polydispersity index improved largely,e.g.,from 0.116,0.084,0.071and 0.102to 0.013,0.007,0.006and 0.009for 80nm,260nm,740nm and 5l m silica particles,respec-tively.The separation time and ef?ciency were easily adjusted by regulating the centrifugal speed,gradient formulation and fractionation size.With the uniformed particles,better photonic crystals (PCs)were assembled,with stopband width largely sharpened,e.g.,from 66nm to 16nm for a 260-nm-silica-assembled PC,and stopband re?ectivity extensively enhanced from 75%up to even 99%.This method can also be extended to unify other spherical particles.

ó2015Elsevier B.V.All rights reserved.

1.Introduction

Submicron silica particles that can be synthesized in laboratory [1–3]are an excellent type of basic materials to build photonic crystals (PCs)for analytical applications such as sensing [4–6],detection [7,8],high performance

separation [9–11]and so forth.However,it remains hard to synthesize highly uniform particles.No matter how ?nely are the synthetic approaches designed and

https://www.doczj.com/doc/e817625464.html,/10.1016/j.cej.2015.02.051

1385-8947/ó2015Elsevier B.V.All rights reserved.

Abbreviations:CF,cutoff fractionation;FsF,?nely sectioned fractionation;PC(s),photonic crystal(s);PDI,polydispersity index;RZC,rate-zonal

centrifugation;SEM,scanning electron microscopy;TEM,transmission electron microscopy;TEOS,tetraethylorthosilicate;d ,diameter of a particle;f ,frictional coef?cient;F c ,centrifugal force;F b ,buoyant force;F f ,frictional force;m ,mass;r ,centrifugal radium of a particle;g ,viscosity;q ,density;t ,velocity;x ,angular velocity.?Tel.:+861062618240;fax:+861062559373.E-mail address:chenyi@https://www.doczj.com/doc/e817625464.html, (Y.Chen).

performed,the resulting silica particles are commonly not really monodispersed but with their diameter varying over a certain range,about2%in the best case[2],which degrades the quality of assembled PCs and their analytical applications.In order to increase the size-uniformity of the submicron silica particles,one may try to further optimize the existed synthetic methods or invent a totally new approach,but it looks also straightforward to conduct a step of post-synthesis separation.

Several potential separation methods are available at present and some of them have been tried in the separation of nanoparti-cles,for instance,centrifugation[12–15],size exclusion chro-matography[16],?ltration[17],selective precipitation[18]and electrophoresis[19,20].These methods offer the chance to uniform the particle size by fractionation during or after separation.Among them,the centrifugation has the advantages of easy manipulation and appropriate separation power in combination with density gradient media.There are two basic forms of density gradient cen-trifugations,the isopycnic and the rate-zonal centrifugation.The isopycnic centrifugation separates particles on the basis of their density difference.The particles will sediment to the equidensity positions.This method has been widely used to separate biomole-clues or organs,such as proteins[21],nucleic acids[22],and lyso-somes[23]et al.In rate-zonal centrifugation(RZC),the sample has greater density than the gradient,the particles are separated by the difference of sedimentation velocity which is determined by both the characters of particles(size,shape,and density)and separation medium(density and viscosity).Prantner et al.[24]have used sucrose density gradient ultracentrifugation to purify magnetic nanoparticles,and Akbulut[25]demonstrated that rate-zonal cen-trifugation with aqueous multiphase could separate gold nanopar-ticles with different shapes and sizes.Chen[26]could isolate gold nanoparticle dimers and trimers by centrifugation with high den-sity CsCl2solutions.The viscosity gradient is also used in RZC to sort nanoparticles,Qiu[14]used a pure viscosity gradient built from aqueous polyvinylpyrrolidone solutions to sort gold nanopar-ticles.Bonaccorso[27]also separated gold nanoparticles by ethy-lene glycol viscosity gradient.

To the best of our knowledge,there remains no trial to centrifu-gally separate the submicron particles which are much heavier than the typical nanoparticles.They may be too heavy to have an equidensity liquid to hold them.We have tried to use heavy salts such as CsCl2to build up denser media but the salts caused precip-itation and worsened the separation,possibly due to the serious adsorption of CsCl2or their ions on the silica particles.Therefore, we returned to the use of sucrose which is cheap and,more impor-tantly,does not perturb the surface chemistry of the particles, besides,their density and viscosity can easily be picked up from some Sugar Handbooks[28].

To separate silica particles which have not been uniformed by centrifugation before,repeated experiments should be tried?rst to optimize the separation condition.It is hence tedious,time con-suming and materials wasting.To avoid the blind trial and error we conducted theoretical derivation and calculation to direct the experiment.As in RZC,the particles are denser than separation medium,they will keep sediment until hitting the bottom of a centrifugal tube.The separation time has thus to be well counted to avoid incomplete separation or co-precipitation of particles.By analyzing the force balance of a particle in centrifugation,we derived a predictive model that quantitatively links the cen-trifugation time with centrifugal speed,gradient formulation,and fractionation size.In this case,the separated particles were suc-cessfully prevented from mixing again and/or precipitating toward the tube bottom without awareness.The method was validated to work properly in the separations of as-synthesized silica particles. In only a single separation taking merely1min could the silica par-ticles be uniformed,with the polydispersity index(PDI)improved from0.084to0.002.Utilizing the uniformed particles,better PCs were assembled,with sharp and deep stopband(e.g.,stopband re?ectivity up to99%for a260-nm silica PC).The method is repeat-able,allowing multiple separation and/or fractionation of particles until they are perfectly uniformed.It is extendable to the uni-formization of other types of particles,and should be a promising strategy considering its simplicity,fastness,economy and sep-aration-effectiveness.

2.Experiment

2.1.Chemicals

Tetraethylorthosilicate(TEOS,98%wt.)and ammonium hydrox-ide(NH3áH2O,28%wt.)were purchased from Alfa Aesar(Ward Hill, MA,USA).Absolute ethanol and sucrose were of analytical reagent grade from Beijing Chemical Work(Beijing,China).Silica particles (5l m)were from Bonna-Agela Technologies Inc.(Tianjin,China). All reagents were used as received.Solutions were prepared in deionized water puri?ed by the Milli-Q water puri?cation system (Millipore,Milford,MA,USA).

2.2.Synthesis of silica particles

All sub-micro silica particles were prepared by emulsi?er-free emulsion polymerization according to the St?ber–Fink–Bohn method[1].Brie?y,to synthesis262nm silica particles,ethanol (100mL),water(6.3mL)and28%ammonium hydroxide(5.1mL) were mixed by magnetic stirring in a round-bottomed?ask warmed in a water bath at28°C,followed by fast addition of 6mL TEOS.After reaction for12h,the particles were harvested by centrifugation,and washed?rst with pure ethanol for4times and then with water until pH7.The washed particles were dried at80°C for6h and re-dispersed in water at2%(w/v)for centrifugal separation.

This procedure was used for the synthesis of other silica parti-cles but the concentration of ammonium hydroxide and related chemicals were varied according to particles size(Table1).

2.3.Uniformization of the synthesized silica particles by centrifugal separation

Sucrose solutions were prepared by dissolving sucrose in deionized water by sonication.An aliquot of0.7mL each sucrose solutions was carefully?lled into a5mL centrifugal tube in a con-centration sequence of700mg/mL,600mg/mL,500mg/mL and 400mg/mL(from bottom to top).A silica colloid suspension(nor-mally300l L at20mg/mL)was then carefully loaded onto the top of the sucrose gradient and centrifuged at25°C on an Eppendorf 5430R Centrifuge(Eppendorf Co.,Ltd.,German).The spinning speed and time were set at60–2000g and30–180s,respectively, depending on the particle size to be separated.After centrifugation, the silica particles were collected by pipetting layer-by-layer the liquid from top to bottom,and washed with deionized water for three times.The same particles were divided into three parts,each part conducted the same RZC,the separated particles were Table1

Recipes for synthesis of silica particles with different sizes.

Particle size(nm)NH3áH2O(mL)Water(mL)Ethanol(mL)TEOS(mL)

80 1.216.610017.8

280 6.0 6.3100 6.0

3609.1 6.3100 6.0

44012.3 6.3100 6.0

74020.7 6.3100 6.0

C.Hu,Y.Chen/Chemical Engineering Journal271(2015)128–134129

collected in the same way and?nally put together to conduct the following washing and SEM measurement.

Two fractionation approaches were tried,cutoff fractionation (CF)and?nely sectioned fractionation(FsF).By CF,the separated zone was divided into three parts,including the upper uneven bor-der,the middle part,and the lower uneven border.The two uneven borders were abandoned,only the middle part was collected; while by FsF,the separated zone was equally divided into?ve lay-ers and only the central layer was collected and used.

2.4.Assemble of PCs

Photonic crystals were prepared by evaporation-induced verti-cal deposition[29].A glass slide was vertically inserted into a cov-ered glass container?lled with2%(w/v)silica particles suspended in ethanol,and let the particles assemble onto the glass slide by natural evaporation for3–4days(until all the solvent was evapo-rated completely).Before assembly,all the glassware(slides and container)were cleaned by immersing in H2SO4/H2O2(7:3,v/v) solution for12h.They were then successively rinsed with deion-ized water and anhydrous ethanol in an ultrasonic bath,and?nally dried by nitrogen gas?ow.

2.5.Characterization

Transmission electron microscopy(TEM)was conducted on a JEM-1011instrument(JEOL Co.,Japan)at100kV.Samples were prepared by direct deposition of dilute dispersions onto copper grids coated with formvar and a carbon layer(EMS Corp.,USA). Scanning electron microscopy(SEM)was performed using a Hitachi S-4800instrument(Hitachi Co.,Japan).Samples were pre-pared by spin-coating a silica particle suspension onto the silicon slice,a layer of gold?lm was then coated on the slice by vacuum evaporation deposition.An accelerating voltage of10kV was used to image the sample.The average size and its PDI were determined from SEM and TEM images by averaging diameters of more than 100particles2.PDI=(r/d)2,where the r is standard deviation,d is the mean diameter.Surface morphologies of the assembled PCs were characterized by SEM,the PC beds were?rst?xed on the basement with a conductive tape and then coated with a layer of gold?lm.

All the optical re?ectance spectra of PCs were measured using an Ocean Optics USB4000-VIS–NIR spectrometer(Ocean Optics Co.,USA),and the photographs were taken by a Canon450D digital camera(Canon INC.,Japan).

3.Results and discussion

3.1.Theory-directed centrifugation

In RZC,the centrifugal time should be long enough to well sepa-rate the nonuniform particles but has to be restricted to the point just before the particles reach the bottom.In order to have a clear guidance,a quantitative equation was thus derived to estimate separation time.There are four forces that act on a particle in cen-trifugation:(1)centrifugal force,F c=mp x2r;(2)gravity which is so small that it is negligible in most cases;(3)buoyant force, F b=àm p x2r q m/q p;and(4)frictional force,F f=àf v,where q p and q m denote the density of the particles and the separation media,

respectively,m p is the mass of the particle(m p=p d3q p/6for a spherical nanoparticle with a diameter of d),x angular velocity,r centrifugal radium of a particle,f frictional coef?cient(f=3pg d for a spherical particle,where g is the viscosity),and t the velocity of the particle being centrifuged.Once centrifugation starts,the particle will?rst be accelerated toward the tubing bottom and then moves at a steady velocity t as the forces become balanced or F c+F b+F f=0,thus we have:

t?e

q

p

àq mTd2

18g

x2re1T

Eq.(1)shows that the sinking speed of the particle is proportional to its density difference from the centrifugal medium,to the square of particle size and centrifugal spinning velocity but inversely proportional to the viscosity and/or the concentration of sucrose in the centrifugal medium.Considering that,in gradient cen-trifugation,a particle needs to pass through many liquid layers with increasing gradients,the centrifugal time will vary with the layer number n(Fig.1),and the total time to reach the tube bottom can be estimated as follows:

t?

X i?n

i?1

t i?

X i?n

i?1

L i

t i?

X i?n

i?1

18g i L i

eq pàq m

i

Td x2r

e2T

Thus the minimum and maximum centrifugal times can be esti-mated by giving all the layers having the lowest and the highest density,respectively:

t min%nt1?n18g1L1

epàm

1

Td22r

t max%nt n?n18g n L n

eq pàq m nTd x2r

8

><

>:e3T

Here we suppose that the layer1has the lowest density while the layer n has the highest density.Clearly,the centrifugal time is now reversely proportional to the liquid density,centrifugal speed and particle size,or in short,a larger particle needs a shorter time to sink to the bottom.The biggest particles with d max will take the shortest centrifugation time of t min to pass through the most dilute sucrose solutioneq m

1

;g1Twhile the smallest particles with d min takes the longest time of t max to pass through the most con-densed sucrose solutioneq m

n

;g nT.A particle with a size between d max and d min will take a centrifugal time t i in between t min and t max.In cooperation these into Eq.(3),we can have a guiding equa-tion in respect of centrifugation time:

n

18g1L1

eq pàq m

1

Td2

max

x2r

18g n L n

eq pàq m nTd2min x2r

e4T

Eq.(4)also shows that the separation time can easily be regu-lated by adjusting either the density of sucrose solution or the cen-trifugal speed.They are in practice convenient to control.Although RZC can be used to separate unspherical particles[30],Eq.(4)can only be applied to spherical particles.For unspherical particles,the rotational Brownian motion of the particles cannot be ignored and the shape factor is important,the frictional coef?cient f is hence much more complex,so the derived equation should be modi?ed.

130 C.Hu,Y.Chen/Chemical Engineering Journal271(2015)128–134

3.2.Validation of the theoretical estimation

To verify the feasibility of the theoretical estimation on the cen-trifugal time,mixed silica particles with diameters of 280nm,360nm and 440nm were chosen as models and centrifuged.convenience,the centrifugal speed was regulated to adjust the time for it is easy in manipulation.By this control,the sucrose den-sity gradients could be preserved for the purpose to improve the resolution.A ?ve-layered sucrose density gradient was composed:top at 400mg/mL sucrose (q m 1=1.124g/cm 3and g 1=2.6cP °C);middle at 500mg/mL,600mg/mL and 700mg/mL sucrose,

2.Centrifugal separation of 280,360and 440nm silica particles,through gradient of 400,500,600,700,and 800mg/mL sucrose layered from top to bottom,25°C,600g ,and centrifugal time of 30,60,120and 180s,respectively.The SEM results illustrate the size and shape distribution of separated silica particles.

fractionation (A1,B1,C1,D1)of (A)80nm,(B)260nm,(C)740nm and (D)5l m silica particles and their related (A2and A3)(A2,B2,C2,D2)and after (A3,B3,C3,D3)centrifugation through a density gradient composed of (all from top to bottom)700;(C1)500,600,700and 800;and (D1)928,1222,1500and 1632mg/mL sucrose,at a centrifugal force of (A)and (D)60g for 30s,respectively.

Impact of sample concentration(A)and volume(B)on the centrifuged

distribution.The testing particles were260nm silica particles suspended

water at different concentrations,or at(B)20mg/mL in different volumes.

centrifugation was performed at25°C and600g for2min,through a

of(from top to bottom)400,500,600,and700mg/mL sucrose.

features on the uniformity of particles illustrated by either(left column)irised colour pictures,(middle column)SEM

were the(A)as-synthesized,(B)cutoff-fractionated,(C)?ne-fractionated,and(D)doubly cutoff-fractionated

by centrifugation through a density gradient of(from top to bottom)400,500,600and700mg/mL sucrose.(For interpretation legend,the reader is referred to the web version of this article.)

improved,from0.116,0.084,0.071and0.102to0.013,0.007,0.006 and0.009for80nm,260nm,740nm and5l m silica particles respectively,which were calculated from the SEM pictures and averaged three times.

3.4.Impact of sample load

Sample load was found to have a great impact on the uni-formization of particles.Overloading caused extra broadening of the centrifugal zone.There are two factors concerned,sample con-centration and volume.By checking with260nm silica particles at a giving volume of300l L,the particle concentration was found to be better kept below25mg/mL(Fig.4A).Above the point,the zone was starting to dislocate or to be deformed;while below the point, the zones maintained their Gaussian distribution.In order to have as high productivity as possible,the loading of20mg/mL silica par-ticles was suggested and adopted for further experiment.The impact of sample volume on the separation was also checked by the silica particles.Fig.4B shows that the dislocation or asymmetry is negligible even up to a volume of400l L,but a volume of300l L was generallychosen in this study to keep the initial particle zone within a properly narrow level.

3.5.Validation via assembling better PCs

It has been con?rmed that the proposed method is able to effectively improve the uniformity of as-synthesized silica parti-cles in a manner of controlled centrifugation.Herein it was further validated that the centrifugally uniformed particles were suitable for assembly of better PCs.The quality of the obtained PCs was undoubtedly improved as the uniformity of the used particles was increased by CF(PDI=0.007,Fig.5B)or FsF(PDI=0.004, Fig.5C)or double CF(PDI=0.002,Fig.5D)if compared with the nonuniform silica particles(PDI=0.086,Fig.5A).The improved quality was characterized not only by the irised color of the assem-bled PCs(Fig.5,left column)but also by SEM pictures(Fig.5,the middle column)and more persuasively,by the stopband features, i.e.,the band width and re?ectivity,(Fig.5,the right column). The band width measured by the full-width-at-half-maxima has been improved from66nm for the nonuniform particles (Fig.5A3)to16nm for the uniformed ones(Fig.5D3),and the re?ectivity enhanced from75%(Fig.5A3)to99%(Fig.5C3–D3). Further improvement of the uniformity of the particles can be achieved by conducting even more times of centrifugation through ?ner separation gradient or even thinner fractionation,but it should be compromised between the uniformity and the cost of time and production.According to our data,double FsF would be proposed for the preparation of better PCs.

4.Conclusions

A theory-guided density gradient centrifugation method was proposed to uniform as-synthesized particles.With silica particles as testing models,the method was shown to be very effective in the uniformization of various size particles using cheap sucrose as separation gradient.The resolution and separation time were easily regulated by either adjusting the centrifugal force or the gradient formula.One issue we should pay attention to is that the particle amount should not be overloaded to have sharp and symmetrical centrifugal zones.The effectiveness of the proposed method have been con?rmed by the great improvement of particle PDI and concretely validated by the largely improved intrinsic fea-ture of PCs assembled from the uniformed particles.This method is clearly easy in manipulation,nearly costless and especially?exible.It is also extendable to the uniformization of any other spherical particles.

Acknowledgements

This work was?nancially supported by NSFC(Nos.21235007& 21475136)and MOST(Nos.2012IM030400&2012IM030900). Appendix A.Supplementary data

Supplementary data associated with this article can be found,in the online version,at https://www.doczj.com/doc/e817625464.html,/10.1016/j.cej.2015.02.051. References

[1]W.St?ber,A.Fink,E.Bohn,Controlled growth of monodisperse silica spheres in

the micron size range,J.Colloid Interface Sci.26(1968)62–69.

[2]K.D.Hartlen,A.P.T.Athanasopoulos,V.Kitaev,Facile preparation of highly

monodisperse small silica spheres(15to>200nm)suitable for colloidal templating and formation of ordered arrays,Langmuir24(2008)1714–1720.

[3]Z.Luo,X.Cai,R.Y.Hong,L.S.Wang,W.G.Feng,Preparation of silica

nanoparticles using silicon tetrachloride for reinforcement of PU,Chem.Eng.

J.187(2012)357–366.

[4]J.MacLeod,F.Rosei,Photonic crystals:sustainable sensors from silk,Nat.

Mater.12(2013)98–100.

[5]N.Griffete,H.Frederich,A.Ma?tre,C.Schwob,S.Ravaine,B.Carbonnier,M.M.

Chehimi, C.Mangeney,Introduction of a planar defect in a molecularly imprinted photonic crystal sensor for the detection of bisphenol A,J.Colloid Interface Sci.364(2011)18–23.

[6]G.L.Shang,G.T.Fei,Y.Zhang,P.Yan,S.H.Xu,L.D.Zhang,Preparation of narrow

photonic bandgaps located in the near infrared region and their applications in ethanol gas sensing,J.Mater.Chem.C1(2013)5285–5291.

[7]C.S.Huang,V.Chaudhery,A.Pokhriyal,S.George,J.Polans,M.Lu,R.Tan,R.C.

Zangar, B.T.Cunningham,Multiplexed cancer biomarker detection using quartz-based photonic crystal surfaces,Anal.Chem.84(2011)1126–1133. [8]H.Yang,P.Jiang,B.Jiang,Vapor detection enabled by self-assembled colloidal

photonic crystals,J.Colloid Interface Sci.370(2012)11–18.

[9]T.Liao,Z.P.Guo,J.C.Li,M.R.Liu,Yi Chen,One-step packing of anti-voltage

photonic crystals into micro?uidic channels for ultra-fast separation of amino acids and peptides,Lab Chip13(2013)706–713.

[10]S.B.King,K.D.Dorfman,Role of order during Ogston sieving of DNA in colloidal

crystals,Anal.Chem.85(2013)7769–7776.

[11]B.J.Rogers,M.J.Wirth,Slip?ow through colloidal crystals of varying particle

diameter,ACS Nano7(2012)725–731.

[12]H.Ichiura,T.Nakatani,Y.Ohtani,Separation of pulp and inorganic materials

from paper sludge using ionic liquid and centrifugation,Chem.Eng.J.173 (2011)129–134.

[13]D.Steinigeweg,M.Schütz,M.Salehi,S.Schlücker,Fast and cost-effective

puri?cation of gold nanoparticles in the20–250nm size range by continuous density gradient centrifugation,Small7(2011)2443–2448.

[14]P.Qiu,C.Mao,Viscosity gradient as a novel mechanism for the centrifugation-

based separation of nanoparticles,Adv.Mater.23(2011)4880–4885.

[15]V.Snitka,D.O.Naumenko,L.Ramanauskaite,S.A.Kravchenko,B.A.Snopok,

Generation of diversiform gold nanostructures inspired by honey’s components:growth mechanism,characterization,and shape separation by the centrifugation-assisted sedimentation,J.Colloid Interface Sci.386(2012) 99–106.

[16]J.P.Novak,C.Nickerson,S.Franzen,D.L.Feldheim,Puri?cation of molecularly

bridged metal nanoparticle arrays by centrifugation and size exclusion chromatography,Anal.Chem.73(2001)5758–5761.

[17]T.S.Huuha,T.A.Kurniawan,M.E.T.Sillanp??,Removal of silicon from pulping

whitewater using integrated treatment of chemical precipitation and evaporation,Chem.Eng.J.158(2010)584–592.

[18]A.Chemseddine,H.Weller,Highly monodisperse quantum sized CdS particles

by size selective precipitation,Ber.Bunsenges.Phys.Chem.97(1993)636–638.

[19]X.Xu,K.K.Caswell,E.Tucker,S.Kabisatpathy,K.L.Brodhacker,W.A.Scrivens,

Size and shape separation of gold nanoparticles with preparative gel electrophoresis,J.Chromatogr.A1167(2007)35–41.

[20]N.A.M.Yunus,H.Nili,N.G.Green,Continuous separation of colloidal particles

using dielectrophoresis,Electrophoresis34(2013)969–978.

[21]W.L.Gent,N.A.Gregson, C.A.Lovelidge, A.F.Winder,Separation of lipid–

protein complexes of rat brain myelin by isopycnic centrifugation,Biochem.J.

122(1971)63P.

[22]T.Lueders,M.Mane?eld,M.W.Friedrich,Enhanced sensitivity of DNA-and

rRNA-based stable isotope probing by fractionation and quantitative analysis of isopycnic centrifugation gradients,Environ.Microbiol.6(2004)73–78. [23]R.Wattiaux,S.Wattiaux-De Coninck,M.F.Ronveaux-dupal,F.Dubois,Isolation

of rat liver lysosomes by isopycnic centrifugation in a metrizamide gradient,J.

Cell Biol.78(1978)349–368.

C.Hu,Y.Chen/Chemical Engineering Journal271(2015)128–134133

[24]A.M.Prantner,J.Chen, C.B.Murray,N.Scholler,Coating evaluation and

puri?cation of monodisperse,water-soluble,magnetic nanoparticles using sucrose density gradient ultracentrifugation,Chem.Mater.24(2012)4008–4010.

[25]O.Akbulut,C.R.Mace,R.V.Martinez,A.A.Kumar,Z.Nie,M.R.Patton,G.M.

Whitesides,Separation of nanoparticles in aqueous multiphase systems through centrifugation,Nano Lett.12(2012)4060–4064.

[26]G.Chen,Y.Wang,L.H.Tan,M.Yang,L.S.Tan,Y.Chen,H.Chen,High-purity

separation of gold nanoparticle dimers and trimers,J.Am.Chem.Soc.131 (2009)4218–4219.[27]F.Bonaccorso,M.Zerbetto,A.C.Ferrari,V.Amendola,Sorting nanoparticles by

centrifugal?elds in clean media,J.Phys.Chem.C117(2013)13217–13229.

[28]M.Asadi,Beet-Sugar Handbook,?rst ed.,John Wiley&Sons Inc,Hoboken,NJ,

USA,2005.pp.779–801.

[29]P.Jiang,J.F.Bertone,K.S.Hwang,V.L.Colvin,Single-crystal colloidal

multilayers of controlled thickness,Chem.Mater.11(1999)2132–2140. [30]B.Xiong,J.Cheng,Y.Qiao,R.Zhou,Y.He,Edward S.Yeung,Separation of

nanorods by density gradient centrifugation,J.Chromatogr.A1218(2011) 3823–3829.

134 C.Hu,Y.Chen/Chemical Engineering Journal271(2015)128–134

如何写先进个人事迹 篇一：如何写先进事迹材料 如何写先进事迹材料 一般有两种情况：一是先进个人，如先进工作者、优秀党员、劳动模范等；一是先进集体或先进单位，如先进党支部、先进车间或科室，抗洪抢险先进集体等。无论是先进个人还是先进集体，他们的先进事迹，内容各不相同，因此要整理材料，不可能固定一个模式。一般来说，可大体从以下方面进行整理。 (1)要拟定恰当的标题。先进事迹材料的标题，有两部分内容必不可少，一是要写明先进个人姓名和先进集体的名称，使人一眼便看出是哪个人或哪个集体、哪个单位的先进事迹。二是要概括标明先进事迹的主要内容或材料的用途。例如《王鬃同志端正党风的先进事迹》、《关于评选张鬃同志为全国新长征突击手的材料》、《关于评选鬃处党支部为省直机关先进党支部的材料》等。 (2)正文。正文的开头，要写明先进个人的简要情况，包括：姓名、性别、年龄、工作单位、职务、是否党团员等。此外，还要写明有关单位准备授予他(她)什么荣誉称号，或给予哪种形式的奖励。对先进集体、先进单位，要根据其先进事迹的主要内容，寥寥数语即应写明，不须用更多的文字。 然后，要写先进人物或先进集体的主要事迹。这部分内容是全篇材料

的主体，要下功夫写好，关键是要写得既具体，又不繁琐；既概括，又不抽象；既生动形象，又很实在。总之，就是要写得很有说服力，让人一看便可得出够得上先进的结论。比如，写一位端正党风先进人物的事迹材料，就应当着重写这位同志在发扬党的优良传统和作风方面都有哪些突出的先进事迹，在同不正之风作斗争中有哪些突出的表现。又如，写一位搞改革的先进人物的事迹材料，就应当着力写这位同志是从哪些方面进行改革的，已经取得了哪些突出的成果，特别是改革前后的．经济效益或社会效益都有了哪些明显的变化。在写这些先进事迹时，无论是先进个人还是先进集体的，都应选取那些具有代表性的具体事实来说明。必要时还可运用一些数字，以增强先进事迹材料的说服力。 为了使先进事迹的内容眉目清晰、更加条理化，在文字表述上还可分成若干自然段来写，特别是对那些涉及较多方面的先进事迹材料，采取这种写法尤为必要。如果将各方面内容材料都混在一起，是不易写明的。在分段写时，最好在每段之前根据内容标出小标题，或以明确的观点加以概括，使标题或观点与内容浑然一体。 最后，是先进事迹材料的署名。一般说，整理先进个人和先进集体的材料，都是以本级组织或上级组织的名义；是代表组织意见的。因此，材料整理完后，应经有关领导同志审定，以相应一级组织正式署名上报。这类材料不宜以个人名义署名。 写作典型经验材料-般包括以下几部分： (1)标题。有多种写法，通常是把典型经验高度集中地概括出来，一

编订：__________________ 审核：__________________ 单位：__________________ 丁基橡胶装置简介和重点 部位及设备 Deploy The Objectives, Requirements And Methods To Make The Personnel In The Organization Operate According To The Established Standards And Reach The Expected Level. Word格式 / 完整 / 可编辑

文件编号：KG-AO-5622-57 丁基橡胶装置简介和重点部位及设 备 使用备注：本文档可用在日常工作场景，通过对目的、要求、方式、方法、进度等进行 具体的部署，从而使得组织内人员按照既定标准、规范的要求进行操作，使日常工作或 活动达到预期的水平。下载后就可自由编辑。 (一)装置发展及类型 1．装置发展 丁基橡胶在1940年6月问世，1943年投产，是美国的Exxon公司。在世界丁基橡胶生产行业中，Exxon、Bayer公司的丁基橡胶生产技术成熟可靠、水平较高，但从不转让技术，企图长期垄断丁基橡胶生产技术和市场。Exxon公司联合Bayer公司成立了子公司与北京燕化公司进行合作谈判，由于条件苛刻、技术费用很高，因而未有结果。 意大利的Pressindustria公司(以下简称n公司)从1971年开始对丁基橡胶理论开始研究1973年为Exxon公司提供搅拌器，1975年开始与前苏联合作进行新型丁基橡胶聚合反应器的研究，1976年取得成功。

丁腈橡胶/丁苯橡胶并用胶相容性研究 丁腈橡胶是一种强极性橡胶,丁苯橡胶是一种非极性橡胶,二者在热力学上是不相容,两相界面之间很难产生共交联,微观呈现相分离状态,相容性差,导致综合性能差。丁腈橡胶/丁苯橡胶并用胶的相容性直接取决于两相间是否有键合作用的存在,即共交联。 如果两相间产生共交联,那么相容性会得到提高,只有相容性提高了,两相间的相分离才能得到改善,宏观性能才能提高。本文首先采取了一种新的工艺,即两种橡胶分别加各自的配合剂制成母炼胶,停放一段时间,制备并用胶。 通过这种工艺,硫化剂一部分存在于各自的橡胶相中,可以防止在硫化时,由于胶料粘度的不同导致的硫化剂迁移问题,保证各组分都能得到有效交联;另一部分富集在二者相交的相界面上,从而可能在相界面上发生共交联等反应;通过拉伸试验对比发现新工艺比传统工艺的性能要好。通过对比例50/50进行傅里叶变换红外光谱分析(FT-IR)、交联密度测定、差示扫描量热分析(DSC)、扫描电子显微镜(SEM)的研究,结果表明:新工艺50/50产生了氢键,交联密度增大,产生了共交联,玻璃化转变温度相互靠近,断面粗糙程度增加,断裂纹的高度和宽度明显增加,且分散密集,说明断裂趋于韧性断裂,需要更多的断裂能量,即两相之间相互作用增强,界面间结合更加牢固,因此NBR/SBR并用胶相容性提高,性能提高。 其次在新工艺的基础上采取了硅烷偶联剂,利用其在高温下释放的活性硫,研究是否参与了界面间的共交联反应。通过无转子发泡硫化仪、DSC、扫描电子显微镜(SEM)对并用胶硫化特性、玻璃化转变温度、微观形貌之间关系的研究,结果表明:随着双-[γ-(三乙氧基硅)丙基]四硫化物(Si69)用量的增多,门尼粘度降低,硬度增加,拉伸强度增高,断裂伸长率下降;耐油性能变好,交联密度增大,

英语演讲稿：未来的工作 这篇《英语演讲稿范文：未来的工作》，是特地，希望对大家有所帮助！ 热门演讲推荐：竞聘演讲稿 | 国旗下演讲稿 | 英语演讲稿 | 师德师风演讲稿 | 年会主持词 | 领导致辞 everybody good afternoon:. first of all thank the teacher gave me a story in my own future ideal job. everyone has a dream job. my dream is to bee a boss, own a pany. in order to achieve my dreams, i need to find a good job, to accumulate some experience and wealth, it is the necessary things of course, in the school good achievement and rich knowledge is also very important. good achievement and rich experience can let me work to make the right choice, have more opportunities and achievements. at the same time, munication is very important, because it determines whether my pany has a good future development. so i need to exercise their municative ability. i need to use all of the free time to learn

小学生个人读书事迹简介怎么写800字 书,是人类进步的阶梯,苏联作家高尔基的一句话道出了书的重要。书可谓是众多名人的“宠儿”。历来,名人说出关于书的名言数不胜数。今天小编在这给大家整理了小学生个人读书事迹,接下来随着小编一起来看看吧! 小学生个人读书事迹1 “万般皆下品,惟有读书高”、“书中自有颜如玉,书中自有黄金屋”,古往今来,读书的好处为人们所重视,有人“学而优则仕”,有人“满腹经纶”走上“传道授业解惑也”的道路……但是,从长远的角度看,笔者认为读书的好处在于增加了我们做事的成功率,改善了生活的质量。 三国时期的大将吕蒙,行伍出身,不重视文化的学习,行文时,常常要他人捉刀。经过主君孙权的劝导,吕蒙懂得了读书的重要性,从此手不释卷,成为了一代儒将,连东吴的智囊鲁肃都对他“刮目相待”。后来的事实证明,荆州之战的胜利,擒获“武圣”关羽,离不开吕蒙的“运筹帷幄,决胜千里”,而他的韬略离不开平时的读书。由此可见,一个人行事的成功率高低,与他的对读书,对知识的重视程度是密切相关的。 的物理学家牛顿曾近说过,“如果我比别人看得更远,那是因为我站在巨人的肩上”,鲜花和掌声面前,一代伟人没有迷失方向,自始至终对读书保持着热枕。牛顿的话语告诉我们,渊博的知识能让我们站在更高、更理性的角度来看问题,从而少犯错误,少走弯路。

读书的好处是显而易见的,但是,在社会发展日新月异的今天,依然不乏对读书,对知识缺乏认知的人,《今日说法》中我们反复看到农民工没有和用人单位签订劳动合同,最终讨薪无果;屠户不知道往牛肉里掺“巴西疯牛肉”是犯法的;某父母坚持“棍棒底下出孝子”,结果伤害了孩子的身心,也将自己送进了班房……对书本,对知识的零解读让他们付出了惨痛的代价,当他们奔波在讨薪的路上,当他们面对高墙电网时,幸福,从何谈起?高质量的生活,从何谈起? 读书,让我们体会到“锄禾日当午,汗滴禾下土”的艰辛;读书,让我们感知到“四海无闲田,农夫犹饿死”的无奈;读书,让我们感悟到“为报倾城随太守,西北望射天狼”的豪情壮志。 读书的好处在于提高了生活的质量,它填补了我们人生中的空白,让我们不至于在大好的年华里无所事事,从书本中,我们学会提炼出有用的信息,汲取成长所需的营养。所以,我们要认真读书,充分认识到读书对改善生活的重要意义,只有这样,才是一种负责任的生活态度。 小学生个人读书事迹2 所谓读一本好书就是交一个良师益友,但我认为读一本好书就是一次大冒险,大探究。一次体会书的过程,真的很有意思,咯咯的笑声,总是从书香里散发;沉思的目光也总是从书本里透露。是书给了我启示,是书填补了我无聊的夜空,也是书带我遨游整个古今中外。所以人活着就不能没有书,只要爱书你就是一个爱生活的人,只要爱书你就是一个大写的人,只要爱书你就是一个懂得珍惜与否的人。可真所谓

丁基橡胶装置简介和重点部位及设备 (一)装置发展及类型 1．装置发展 丁基橡胶在1940年6月问世，1943年投产，是美国的Exxon公司。在世界丁基橡胶生产行业中，Exxon、Bayer公司的丁基橡胶生产技术成熟可靠、水平较高，但从不转让技术，企图长期垄断丁基橡胶生产技术和市场。Exxon公司联合Bayer公司成立了子公司与北京燕化公司进行合作谈判，由于条件苛刻、技术费用很高，因而未有结果。 意大利的Pressindustria公司(以下简称n公司)从1971年开始对丁基橡胶理论开始研究1973年为Exxon公司提供搅拌器，1975年开始与前苏联合作进行新型丁基橡胶聚合反应器的研究，1976年取得成功。1983年PI公司对前苏联的下卡姆斯丁基橡胶厂的聚合反应器和聚合工艺进行改造，使其生产水平大大提高。1986年PI公司开始投入大量资金，完善了聚合反应器和聚合工艺技术，开发了聚合反应器数学模型，并通过引进专家掌握了丁基橡胶成套生产技术。 北京燕化公司同俄罗斯及PI公司进行了技术交流，并于1995年12月15日由中国石化总公司召开“关于引进意大利PI公司技术建设丁基橡胶生产装置论证会”，进而确定引进公司的技术建设在中国大陆建设一套3X104t／a的丁基橡胶装置。1997年10月14日，丁基橡胶装置在北京燕山石油化工股份有限公司合成橡胶事业部开始动工，于1999年12月28日正式投产。

2。装置类型 丁基橡胶装置是以高纯度异丁烯和异戊二烯为原料，用高纯度三氯化铝加微量水为催化剂，氯甲烷为稀释剂，采用淤浆法生产丁基橡胶的石油化工装置。是制造子午胎内胎和无内胎轮胎不可代替的材料，在包括电子、机械、医疗和食品等行业中有着非常广泛的用途。 (二)单元组成与工艺流程 1．单元组成 丁基橡胶装置主要由乙烯制冷单元、丙烯制冷单元、配料及催化剂配制单元、聚合和脯气单元、氯甲烷回收单元、氧化铝干燥再生单元、异丁烯和异戊二烯精制单元、中间罐区公用工程系统和后处理生产线等10个单元组成。 2．工艺流程概述 丁基橡胶是在极低的操作温度和半连续生产的条件下用异丁烯和异戊二烯聚合得到。催化剂为用氯甲烷作溶剂配制成的无水三氯化铝溶液，该催化剂溶液经过深冷进入到反应器。精制后的异丁烯和异戊二烯也用氯甲烷按一定比例配制成溶液，经过深冷后进人聚合反应器，在反应器中异丁烯和异戊二烯在催化剂存在下瞬时完成聚合反应，生成丁基橡胶胶粒。胶粒和未反应的单体和氯甲烷自聚合反应器顶部溢出进入到脱气釜用热水脱气，蒸出未反应的大部分单体和氯甲烷。在脱气釜中加入分散剂和抗氧剂，并加入烧碱溶液中和三氯化铝水解生成的盐酸。经脱气后的胶粒和水再经第一汽提釜和第二汽提釜进一步蒸出未反应的单体氯甲烷。

注射用溴化丁基橡胶塞包材相容性研究 李云峰 常山凯捷健生物药物研发（河北）有限公司 摘要：以河北橡一医药科技股份有限公司生产的注射用溴化丁基橡胶塞为研究对象，采用HPLC法对其中的可提取硫和抗氧剂BHT含量进行检测，并对以肝素钠注射液为提取液的胶塞进行研究。实验表明河北橡一医药科技股份有限公司生产的三个批号的胶塞通过适宜溶剂浸提，可获得可提取硫及抗氧剂BHT。在以肝素钠注射液为提取液的供试品中，无可提取硫及BHT浸出。 关键词：注射用溴化丁基橡胶塞；可提取硫；BHT；高效液相色谱法 0 引言 药品包装应适用于药品预期的临床用途[1]，相容性是其必须具备的特性之一。相容性研究是为考察药品包装材料与药品之间是否发生严重的相互作用，并导致药品有效性和稳定性发生改变，或者产生安全性风险而进行的一系列试验，包括包装材料对药品的影响，及药品对包装材料的影响[2，3]。 由于注射用溴化丁基橡胶塞直接与药液接触，注射用溴化丁基橡胶塞中在硫化过程中用到了硫，还使用了一些添加剂如抗氧剂BHT （2,6-二叔丁基对甲酚）来增强其性能，笔者通过提取试验对上述目标化合物进行了研究。 1实验部分 1.1材料与试剂 注射液用溴化丁基橡胶塞：河北橡一医药科技股份有限公司；批号：,,；肝素钠注射液（规格：5ml：5000单位)）：本公司自产，批号：140401；肝素钠注射液（规格：5ml：25000单位)）：本公司自产，批号：140402。 丙酮、2,6-二叔丁基对甲酚（BHT）、升华硫、三氯甲烷、无水乙醇。 甲醇、乙腈均为色谱纯。 1.2仪器 戴安U3000高效液相色谱仪；梅特勒FE20 型酸度计；梅特勒XS105型电子天平；西安安泰MCR-3型微波化学反应器。

关于坚持的英语演讲稿 Results are not important, but they can persist for many years as a commemoration of. Many years ago, as a result of habits and overeating formed one of obesity, as well as indicators of overall physical disorders, so that affects my work and life. In friends to encourage and supervise, the participated in the team Now considered to have been more than three years, neither the fine rain, regardless of winter heat, a day out with 5:00 time. The beginning, have been discouraged, suffering, and disappointment, but in the end of the urging of friends, to re-get up, stand on the playground. 成绩并不重要，但可以作为坚持多年晨跑的一个纪念。多年前，由于庸懒习惯和暴饮暴食，形成了一身的肥胖，以及体检指标的全盘失常，以致于影响到了我的工作和生活。在好友的鼓励和督促下，参加了晨跑队伍。现在算来，已经三年多了，无论天晴下雨，不管寒冬酷暑，每天五点准时起来出门晨跑。开始时，也曾气馁过、痛苦过、失望过，但最后都在好友们的催促下，重新爬起来，站到了操场上。 In fact, I did not build big, nor strong muscles, not a sport-born people. Over the past few years to adhere to it, because I have a team behind, the strength of a strongteam here, very grateful to our team, for a long time, we encourage each other, and with sweat, enjoying common health happy. For example, Friends of the several run in order to maintain order and unable to attend the 10，000 meters race, and they are always concerned about the brothers and promptly inform the place and time, gives us confidence and courage. At the same time, also came on their own inner desire and pursuit for a good health, who wrote many of their own log in order to refuel for their own, and inspiring. 其实我没有高大身材，也没健壮肌肉，天生不属于运动型的人。几年来能够坚持下来，因为我的背后有一个团队，有着强大团队的力量，在这里，非常感谢我们的晨跑队，长期以来，我们相互鼓励着，一起流汗，共同享受着健康带来的快

邢台市龙滨橡塑制品有限公司 XINGTAI LONGBIN RUBBER AHD PLASTIC PRODUCTS CO.,LTD 出厂检验报告 产品名称防震胶型号规格 12600101000102 供应厂家芜湖美的检测项目23项 生产日期2015年7 月 22号合格项目22项 检测数量 5 检测日期2015年 7 月 22 号-2015年 8 月5号检测依据防震胶技术条件QMK-J54.037-2011 检测结论 按美的企标要求,本次试验共检项目23项，22项合格，1项不做判定。依据相关标准判定本次试验结果：合格 序号检验项 目 标准要求检验结果备注 1 标志标志内容与图样相符，印刷清楚标志内容与图样相符，印刷清楚合格 2 包装 质量 防振胶用纸箱包装纸箱包装合格 3 颜色黑色黑色合格 4 表面 质量 1.防振胶表面平整、光滑、无杂质、不含异物、 手摸无明显油渍 2.防振胶的结构由正面为保护塑料薄膜（PE）和 背面为离型纸组成 防震胶表面无杂质，较平整，正 面为塑料薄膜，背面为隔离纸 合格 5 结构 尺寸 尺寸规格应满足图纸要求，未注尺寸公差应符合 GB/T 3672-2002《模压、压出和压延实心橡胶制 品的尺寸公差》（厚度公差EC3与长、宽度公差 L3）级要求。详见下表。 详见下表。合格 6 初粘 性 室温下不小于20#球且实物粘贴无起翘、开 口、位移、流挂等不良现象。 实物黏贴良好，无翘边、流挂等 现象 合格 7 装配 性 a、将两块面积为100mm2的防振胶对粘，压缩 10％，然后沿接触处缓慢撕开（撕开时间≥5秒）， 中间能够拉出≥400mm的连接丝； b、将防振胶长边对包在有2个弯位的铜管 上（对包开口与铜管折弯方向相反，防振胶长边 要大于铜管弯位长度，见下图），压缩式样厚度 为原来的20%，在常温下（25℃）放置2h，2h 防震胶对沾拉丝460mm 防震胶对沾黏于铜管上，放置2 小时无反弹、松弛 合格

顺丁橡胶装置简介和重点部位及设备 一、装置简介 (一)装置发展及类型 1。装置发展 1959年日本的Bndgestone公司开始研制镍系BR顺丁橡胶，并于1964年年底建成2．5x104t／a的生产装置。顺丁橡胶在中国的研究1959年也已开始，经过大量的实验，完成了小试、中试及工业，眭实验。又通过全国性的攻关会战，进而取得了万吨级工业装置的数据。聚合技术开发始于1959年，中国科学院长春应用化合研究所开始了催化剂的开发工作。1965年在锦州和兰州开始了中试，1966年建成生产能力为1000t／a的实验装置。1969年确立了以抽余油为溶剂的生产工艺。1971年在北京燕山石油化工公司合成橡胶厂建成了我国第一套1．5X104t ／a的生／c装置，并生产出了合格的顺丁橡胶。此后，又在锦州石化公司、上海高桥化工厂、齐鲁石化公司橡胶厂、巴陵石化公司合成橡胶厂等相继建成了4套工业生产装置。 我国的顺丁橡胶技术经过多年的不断改进和多次技术攻关，工艺逐渐完善，产品质量稳步提高，已经向欧、美及东南亚等国家出口。同时顺丁橡胶成套技术已经成功实现了对意大：利和我国台湾省的技术转让。 2000年，我国生产顺丁橡胶的厂家已发展到8个，现有生产能力已经达到31．34X104；t／a，。 2．装置类型

顺丁橡胶的关键技术是聚合技术。生产顺丁橡胶的催化剂体系有锂、钛、钴、镍、钕等。不同的催化剂得到的不同橡胶结构的橡胶，用锂系催化剂得到的橡胶 顺式1，4—结构含量为35％—40％，称为低／顷式聚丁二烯橡胶，用钛系催化剂得到的橡胶，顺式含量为90％，由钴、镍、钕系制得的橡胶，顺式含量为96％—98％，统称为高顺式聚丁二烯橡胶，即顺丁橡胶。我国生产顺丁橡胶聚合所采用的催化 剂为镍系。 丁二烯抽提所用的萃取剂目前国内一般采用N，N—二甲基甲酰胺(DMF)和乙腈。本节主要以DMF法抽提丁二烯为主进行介绍。 (二)单元组成与工艺流程 1．单元组成 顺丁橡胶生产装置主要由丁二烯抽提、聚合及凝聚、干燥、成型包装等三大 单元组成。丁二烯抽提单元是／顷丁橡胶装置的龙头，绝大部分丁二烯含量43％左右的混合碳四馏分在这里经过萃取和精馏，从而直接从碳四馏分中提取高纯度 的丁二烯单体供聚合单元使用。 丁二烯聚合单元是顺丁橡胶装置的核心反应部分，是顺丁橡胶生产的心脏， 其任务是将丁二烯、催化剂、溶剂油在规定的工艺条件下进行配位阴离子聚合， 经聚合釜的连续聚合，得到顺式含量大于96％的1．4聚丁二烯胶液，然后加入 防老剂，经静态混合器送往胶液罐，供凝聚单元使用。 凝聚单元主要是应用水蒸气蒸馏原理，借助于热水、蒸汽以及机械搅拌等作用，完成对丁二烯胶液中的溶剂及未反应的丁二烯除去并回收，将悬浮在凝聚釜 中的颗粒状经脱水、干

关于工作的优秀英语演讲稿 Different people have various ambitions. Some want to be engineers or doctors in the future. Some want to be scientists or businessmen. Still some wish to be teachers or lawers when they grow up in the days to come. Unlike other people, I prefer to be a farmer. However, it is not easy to be a farmer for Iwill be looked upon by others. Anyway,what I am trying to do is to make great contributions to agriculture. It is well known that farming is the basic of the country. Above all, farming is not only a challenge but also a good opportunity for the young. We can also make a big profit by growing vegetables and food in a scientific way. Besides we can apply what we have learned in school to farming. Thus our countryside will become more and more properous. I believe that any man with knowledge can do whatever they can so long as this job can meet his or her interest. All the working position can provide him with a good chance to become a talent. 1 ————来源网络整理，仅供供参考

KXT型橡胶减震器（简介） 名称：橡胶减震器 型号：KXT型 橡胶软接头又称作减振器、管道减震器、避震喉、软接头等。本产品引进国外先进生产工艺，制作过程中内层受到高压力，锦纶帘子布和胶层得到更好的结合，比普通型可曲挠橡胶接头的工作压力更高，质量更好。它的特点是内胶层混然一体，光洁无缝痕，标签采用硫化工艺，与产品结合在一起。 详细介绍 橡胶软接头，该产品是金属管道的柔性联接器，由内胶层、锦纶帘子布增强、外胶层复合的橡胶球体和松套金属法兰组成。具有耐压高、弹性好、位移量大、平衡管道偏差、吸收振动、降低噪音效果好、安装方便等特点，可广泛用于供水排水、循环水、暖通空调、消防、造纸、制药、石油化工、船舶、水泵、压缩机、风机等管道系统。普通型用于输送-15℃～115℃的空气、压缩空气、水、海水、油、酸、碱等。特殊型用于输送-30℃～250℃以上的上述介质或油、浓酸浓碱、固态物料。 技术参数 项目 型号 KXT-1 KXT--2 KXT--3 工作压力MPa(kgf/cm2 ) 1.0(10） 1.6（16） 2.5（25） 爆破压力MPa(kgf/cm2 ) 2.0（20） 3.0（30）

4.5（45） 真空度KPa(mm/Hg) 53.3（400） 86.7（650） 100（750） 适用温度℃：-15℃～115℃特殊可达-30℃～250℃ 适用介质：空气、压缩空气、水、海水、热水、油、酸、碱等。

注：1、特殊要求可来函来图定制，法兰按《全国通用给排水标准图集》，其它按HG/T2289-92。 2、DN350-600(2)型工作压力为1.6MPa，DN32-400(3)型工作压力为2.5MPa。 3、DN700-DN1200工作压力为1.0MPa，DN1400工作压力为0.6MPa,DN1600-DN1800工作压力为0.4MPa，法兰按0.6MPa 选取。DN2000工作压力为0.25MPa,法兰按0.6MPa压力选取。 4、悬空给水使用DN200以上产品，管道必须有固定支撑或固定托架，否则产品应安装防拉脱装置。 5、用户使用橡接头，对应法兰应是阀门法兰或符合GB/T9115.1(RF)法兰。

个人先进事迹简介 01 在思想政治方面,xxxx同学积极向上,热爱祖国、热爱中国共产党,拥护中国共产党的领导.利用课余时间和党课机会认真学习政治理论,积极向党组织靠拢. 在学习上,xxxx同学认为只有把学习成绩确实提高才能为将来的实践打下扎实的基础,成为社会有用人才.学习努力、成绩优良. 在生活中,善于与人沟通,乐观向上,乐于助人.有健全的人格意识和良好的心理素质和从容、坦诚、乐观、快乐的生活态度,乐于帮助身边的同学,受到师生的好评. 02 xxx同学认真学习政治理论,积极上进,在校期间获得原院级三好生,和校级三好生,优秀团员称号,并获得三等奖学金. 在学习上遇到不理解的地方也常常向老师请教,还勇于向老师提出质疑.在完成自己学业的同时,能主动帮助其他同学解决学习上的难题,和其他同学共同探讨,共同进步. 在社会实践方面,xxxx同学参与了中国儿童文学精品“悦”读书系,插画绘制工作,xxxx同学在班中担任宣传委员,工作积极主动,认真负责,有较强的组织能力.能够在老师、班主任的指导下独立完成学院、班级布置的各项工作. 03 xxx同学在政治思想方面积极进取,严格要求自己.在学习方面刻苦努力,不断钻研,学习成绩优异,连续两年荣获国家励志奖学金；作

为一名学生干部,她总是充满激情的迎接并完成各项工作,荣获优秀团干部称号.在社会实践和志愿者活动中起到模范带头作用. 04 xxxx同学在思想方面,积极要求进步,为人诚实,尊敬师长.严格 要求自己.在大一期间就积极参加了党课初、高级班的学习,拥护中国共产党的领导,并积极向党组织靠拢. 在工作上,作为班中的学习委员,对待工作兢兢业业、尽职尽责 的完成班集体的各项工作任务.并在班级和系里能够起骨干带头作用.热心为同学服务,工作责任心强. 在学习上,学习目的明确、态度端正、刻苦努力,连续两学年在 班级的综合测评排名中获得第1.并荣获院级二等奖学金、三好生、优秀班干部、优秀团员等奖项. 在社会实践方面,积极参加学校和班级组织的各项政治活动,并 在志愿者活动中起到模范带头作用.积极锻炼身体.能够处理好学习与工作的关系,乐于助人,团结班中每一位同学,谦虚好学,受到师生的好评. 05 在思想方面,xxxx同学积极向上,热爱祖国、热爱中国共产党,拥护中国共产党的领导.作为一名共产党员时刻起到积极的带头作用,利用课余时间和党课机会认真学习政治理论. 在工作上,作为班中的团支部书记,xxxx同学积极策划组织各类 团活动,具有良好的组织能力. 在学习上,xxxx同学学习努力、成绩优良、并热心帮助在学习上有困难的同学,连续两年获得二等奖学金. 在生活中,善于与人沟通,乐观向上,乐于助人.有健全的人格意 识和良好的心理素质.

YF-ED-J7120 可按资料类型定义编号 顺丁橡胶装置危险因素及防范措施实用版 In Order To Ensure The Effective And Safe Operation Of The Department Work Or Production, Relevant Personnel Shall Follow The Procedures In Handling Business Or Operating Equipment. （示范文稿） 二零XX年XX月XX日

顺丁橡胶装置危险因素及防范措 施实用版 提示：该解决方案文档适合使用于从目的、要求、方式、方法、进度等都部署具体、周密，并有很强可操作性的计划，在进行中紧扣进度，实现最大程度完成与接近最初目标。下载后可以对文件进行定制修改，请根据实际需要调整使用。 (一)火灾爆炸危险 火灾爆炸和丁二烯自聚是本装置的主要危 险，丁二烯属于易于自聚的物质，丁二烯生成 端基过氧化自聚物的倾向十分明显。丁二烯端 基聚合物坚硬且不溶于已知溶剂，即便加热也 不能熔融。由于丁二烯生成的端基聚合物在丁 二烯中的溶解度很小，所以很容易沉积在浓缩 层中，黏附在器壁和管道上，造成管道、阀门 和设备堵塞或涨裂。在60—80℃或光照、撞 击、摩擦时能发生爆炸。生产过程对于氧含

量、水含量等要求非常严格，丁二烯在少量的氧存在的情况下就可能被氧化生成过氧化物，引发自聚。过氧化自聚物在空气中的允许浓度仅为100mg／m3，并在125℃以上就可以发生分解爆炸。 此外，乙烯基乙炔是一种极易分解爆炸的物质，当乙烯基乙炔浓度高于50％、分压大于0．075MPa时就有引起爆炸的危险。所以在操作时要严格检查和控制DA—103塔釜温度、溶剂量和回流量，发现异常及时进行处理。 总体而言加强防火防爆、防静电、防泄漏、防丁二烯自聚、防雷等安全措施，应成为本装置关注的重点问题。 (二)毒性危害 丁二烯对人体的危害。慢性中毒对神经系

橡胶兼容性测试要求 1、耐油及耐化学品性能 许多合成橡胶遇油会发生膨胀，或因工作油液中所含的添加剂作用而加速恶化。结果材料在某种 介质中膨胀太大，或性能明显劣化，则说明这两种物质不相容。所以液压气动用密封材料选用时，首先要考虑材料与密封介质是否相容。液压用密封要考虑对工作介质的适应性；气动用密封也要 考虑对润滑剂的耐受性能。 膨胀是指材料遇油后体积发生变化的现象。橡胶的膨胀性能用膨胀率表示，膨胀率是橡胶浸泡前 后的体积变化率。材料膨胀后，密封尺寸关系发生较大的变化，加剧摩擦、磨损，并且强度明显 降低。 除膨胀之外，油液对橡胶的硬度、抗张力、伸长率和残余变形的物理、力学性能均有显著的影响，使橡胶软化、收缩和分解，橡胶性能劣化。这是因为，为了改善橡胶性能，一般都在橡胶中加入 增塑剂，橡胶与油液会吸收橡胶中的增塑剂，随着橡胶中的增塑剂逐渐被溶解，液体侵入，结果 橡胶体积、重量改变，硬度、弹性降低 测定膨胀是考察相容性的一项基本实验。如果不考虑劣化，对材料的膨胀，用作动密封不能超过15%~20%，静密封不超过50%，垫片可接受100%的材料膨胀率。密封件使用中的实际体积变化比 膨胀值要小的多，因为要被压缩变形抵消一部分。 橡胶的膨胀是各种化学品分子进入橡胶聚合物分子之间，产生无规则的分散作用力，使构成橡胶 弹性的网状分子结构发生变化的结果。如果橡胶中的可溶性分子在介质中杂乱无章运动，则橡胶 可能发生收缩，也会对密封造成不利的影响。一般来说，性质相似的物质，这种相互混合的现象 容易发生。例如天然橡胶是碳氢化合物，很容易溶解到同是碳氢化合物的矿物油中去。引用溶解 度参数SP值，可以衡量这种溶解程度。SP值定义为，物质每一摩尔的蒸发热对其体积比值的平 方根，即： SP值=（每摩尔蒸发热/每一摩尔体积）1/2

关于工作的英语演讲稿 【篇一：关于工作的英语演讲稿】 关于工作的英语演讲稿 different people have various ambitions. some want to be engineers or doctors in the future. some want to be scientists or businessmen. still some wish to be teachers or lawers when they grow up in the days to come. unlike other people, i prefer to be a farmer. however, it is not easy to be a farmer for iwill be looked upon by others. anyway,what i am trying to do is to make great contributions to agriculture. it is well known that farming is the basic of the country. above all, farming is not only a challenge but also a good opportunity for the young. we can also make a big profit by growing vegetables and food in a scientific way. besides we can apply what we have learned in school to farming. thus our countryside will become more and more properous. i believe that any man with knowledge can do whatever they can so long as this job can meet his or her interest. all the working position can provide him with a good chance to become a talent. 【篇二：关于责任感的英语演讲稿】 im grateful that ive been given this opportunity to stand here as a spokesman. facing all of you on the stage, i have the exciting feeling of participating in this speech competition. the topic today is what we cannot afford to lose. if you ask me this question, i must tell you that i think the answer is a word---- responsibility. in my elementary years, there was a little girl in the class who worked very hard, however she could never do satisfactorily in her lessons. the teacher asked me to help her, and it was obvious that she expected a lot from me. but as a young boy, i was so restless and thoughtless, i always tried to get more time to play and enjoy myself. so she was always slighted over by me. one day before the final exam, she came up to me and said, could you please explain this to me? i can not understand it. i

一、丁苯橡胶 丁苯橡胶是丁二烯和苯乙烯经共聚合制得的橡胶。英文缩写是SBR。是产量最大的通用合成橡胶，有乳聚丁苯橡胶、溶聚丁苯橡胶。 世界丁苯橡胶生产能力中约87%使用乳液聚合法，通常所说的丁苯橡胶主要是指乳聚丁苯橡胶。乳聚丁苯橡胶又包括高温乳液聚合的热丁苯与低温乳液聚合的冷丁苯。前者于1942年工业化，目前仍有少量生产，主要用于水泥、粘合剂、口香糖、以及某些织物包覆与模塑制品及机械制品。通常所说的丁苯橡胶主要是指低温乳液聚合法生产的丁苯橡胶，1947年工业化，它有较高的耐磨性和很高的抗张强度，良好的加工性能，以及其它综合性能，是目前产量最大、用途最广的合成橡胶品种。 溶聚丁苯橡胶（SSBR）是丁二烯与苯乙烯在烃类溶剂中，在丁基锂催化剂存在下聚合制得。80年代后期生产的第二代溶聚丁苯橡胶滚动阻力优于乳聚丁苯橡胶和天然橡胶，抗湿滑性优于顺丁橡胶，耐磨性也好，可以满足轮胎高速、安全、节能、舒适的要求，用其制造轮胎比乳聚丁苯橡胶节油3%~5%。 丁苯生胶是浅黄褐色弹性固体，密度随苯乙烯含量的增加而变大，耐油性差，但介电性能较好；生胶抗拉强度只有20-35千克力/厘米2，加入炭黑补强后，抗拉强度可达250-280千克力/厘米2；其黏合性﹑弹性和形变发热量均不如天然橡胶，但耐磨性﹑耐自然老化性﹑耐水性﹑气密性等却优于天然橡胶，因此是一种综合性能较好的橡胶。 丁苯橡胶是橡胶工业的骨干产品，它是合成橡胶第一大品种，综合性能良好，价格低，在多数场合可代替天然橡胶使用，主要用于轮胎工业，汽车部件、胶管、胶带、胶鞋、电线电缆以及其它橡胶制品。 二、顺丁橡胶\\聚丁二烯橡胶（BR） 丁二烯在聚合时由于条件不同可产生不同类型的聚合物。高顺式聚丁二烯橡胶1960年在国外正式投入工业生产，我国于1967年工业生产。这种橡胶习惯上称为顺丁橡胶。它是一个大品种的合成橡胶，主要用于轮胎工业。由于顺丁橡胶性能优越，成本较低，所以在橡胶生产中一直占有重要地位。 （1）聚丁二烯橡胶的分类聚丁二烯橡胶主要按制法分类： 溶聚---- 1．高顺式聚丁二烯橡胶（顺式96%-98%，镍、钴、稀土催化剂） 2．低顺式聚丁二烯橡胶（顺式35%-40%，锂催化剂） 3．超高顺式聚丁二烯橡胶（顺式98%以上） 4．低乙烯基聚丁二烯橡胶（乙烯基8%，顺式91%） 5．中乙烯基聚丁二烯橡胶（乙烯基35%-55%）

安全管理编号：YTO-FS-PD750 顺丁橡胶装置简介和重点部位及设备 通用版 In The Production, The Safety And Health Of Workers, The Production And Labor Process And The Various Measures T aken And All Activities Engaged In The Management, So That The Normal Production Activities. 标准/ 权威/ 规范/ 实用 Authoritative And Practical Standards

顺丁橡胶装置简介和重点部位及设 备通用版 使用提示：本安全管理文件可用于在生产中，对保障劳动者的安全健康和生产、劳动过程的正常进行而采取的各种措施和从事的一切活动实施管理，包含对生产、财物、环境的保护，最终使生产活动正常进行。文件下载后可定制修改，请根据实际需要进行调整和使用。 一、装置简介 (一)装置发展及类型 1。装置发展 1959年日本的Bndgestone公司开始研制镍系BR顺丁橡胶，并于1964年年底建成2．5x10的4次方(原多次方位置应该标在右上位置，但word格式不支持)t／a的生产装置。顺丁橡胶在中国的研究1959年也已开始，经过大量的实验，完成了小试、中试及工业，眭实验。又通过全国性的攻关会战，进而取得了万吨级工业装置的数据。聚合技术开发始于1959年，中国科学院长春应用化合研究所开始了催化剂的开发工作。1965年在锦州和兰州开始了中试，1966年建成生产能力为1000t／a的实验装置。1969年确立了以抽余油为溶剂的生产工艺。1971年在北京燕山石油化工公司合成橡胶厂建成了我国第一套1．5X10的4次方(原多次方位置应该标在右上位置，但word格式不支持)t／a的生／c装置，并生产出了合格的顺丁橡胶。此