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正己烷对溶胶-凝胶过程及常压干燥工艺制备SiO 2气凝胶的影响卢斌;张丁日;卢孟磊【摘要】以正硅酸乙酯(TEOS)为硅源，三甲基氯硅烷(TMCS)为表面修饰剂，采用酸碱两步催化溶胶−凝胶法和常压干燥法，通过在凝胶中填充适量正己烷(N-hexane)控制溶胶−凝胶过程，使凝胶孔洞趋于均匀，提高凝胶溶剂置换和表面改性效率，制备高性能SiO2气凝胶，制备工艺周期为30 h。
采用BET，SEM和FT-IR等对样品进行表征。
研究结果表明：正己烷填充量为0.2(TEOS与N-hexane物质的量比为1：0.2)，制备周期最短，制备出的样品具有最大比表面积(972.5 m2/g)、最大孔容(2.9 cm3/g)和最小密度(0.08 g/cm3)，疏水性最佳。
%Silica aerogels were prepared with TEOS as raw material by sol-gel method, surface modification of TMCS and ambient pressure drying within 30 h. Appropriate amount of N-hexane was filled into silica gel to improve efficiency of sol-gel and surface modification process. The structures of samples were characterized by means of BET, SEM and FT-IR etc. The results show that when filler content of N-hexane is 0.2(molar ratio of TEOS to N-hexane is 1:0.2), hydrophobic silica aerogels has low apparent density (0.08 g/cm3), high surface area (972.5 m2/g) and high pore volume (2.9 cm3 /g).【期刊名称】《中南大学学报（自然科学版）》【年(卷),期】2015(000)006【总页数】7页(P2020-2026)【关键词】SiO 2气凝胶;溶胶-凝胶法;常压干燥法;正己烷;胶粒双电层结构【作者】卢斌;张丁日;卢孟磊【作者单位】中南大学材料科学与工程学院，湖南长沙，410083;中南大学材料科学与工程学院，湖南长沙，410083;中南大学材料科学与工程学院，湖南长沙，410083【正文语种】中文【中图分类】O648二氧化硅气凝胶具有极高的比表面积(800~1 500 m2/g)、极大的孔洞率(85%~99%)、极低的热传导率(5 mW/(m·K))和独特的声学性能等，因此，在很多领域发挥重要作用，如用作高性能催化剂、保温涂料、超绝热材料、窗体材料等[1−4]。
硅胶（Silica gel）Silica gel mouldThe silica gel mold is a special mould glue for making crafts. The characteristic of silica gel is high temperature resistance, corrosion resistance, strong tearing resistance and fine simulation. It is a special mold for making various crafts.[Edit] silicone moldThe production process of silicone rubber mold mold form simple ah and the choice of line selection is very important, one is for the convenience of modulus, two is the line should be in does not affect the overall effect of the product is three, does not affect the product quality, such as mold line waterscape series products position is too high, sealing mould line when the material, it is prone to cracking products; four is to reduce the flow of operations, such as half open mode. In order to prevent the flow of the mold with silica gel around the wood or wood in a fixed range of rules, open mold board and sludge separated part of the first open, there is no gap with the requirements of sludge mode between sludge, smooth surface. After the above work prepared, then in plaster mold or mold coated with Vaseline or spray release agent, smooth product requirements with a clean cotton cloth with Vaseline evenly on the mold, the mold for 30 minutes to fully absorb the Vaseline, and then a clean cotton cloth to wipe the surface clean and die, the requirements of surface light; and the texture of the products as long as evenly coated with Vaseline can be adjusted according to the formula of the silica gel. The deployment of silica gel should be based on the irregular direction ofstirring, the curing agent and silica gel mixing, minimize air mixed with glue, smooth the best products in a vacuum pumping coated with a first layer of glue, vacuum requires -0.1Mpa to maintain 7-8 seconds. After the silica gel is matched, the mould should be made in time. Glue with trickle way down in the highest part of the mold, make its natural flowing stream, not in place in place with a painting brush, if it is not only filled the entire piece mold silica gel products and also to brush evenly daub. Each product at least three brush layer thickness of each layer of silica gel silica gel for 1mm, in the process of brush silica gel, each layer after curing can brush another layer in the third layer, brush to add a layer of gauze in the second layer to increase the strength of gel. The silica gel part of the mould is controlled at 3-4mm in accordance with the size of the product, and the width is no more than the width of the product is 60 mm. The silica gel began to solidify for 20 minutes. 1, the female die for dry cleaning, smoothing (can be a layer of wax stripping or brushing again release agent) 2 and 500-1000 grams of mold silicone rubber (silicone mold, mold rubber, silicone rubber, silicone) Sheng plastic basin reserve; 3, hardener by weight ratio (usually 1.5-2.5%) weighing after joining the mixing container, stir; 4, depending on the situation (especially the first layer) by adding a certain amount of silica diluent. Until the mixture is uniform, usually 3-5 minutes. 5. mold silicone rubber (silicone mold, mold rubber, silicone rubber, silicone) and hardening agent, the reaction at room temperature, and the release of low molecular alcohol, the alcohol molecules from the colloid in the lower vacuum soak 1-3 minutes. Also can not use the equipment (mainly as the mold operator's experience) 6, multi layer brushing die, should follow the internal, middle and outer curing at the sametime. When the dosage of curing agent is relatively small, the reaction time is longer, the reaction is sufficient, the colloid is good, so the dosage of curing agent is better than inside. When brushing, the first layer (inner layer) will be dried and then brush second layers. The operation time of 30-50 minutes, the removal time of 10-15 hours. Curing time is 24 hours. Pay attention to brushing first, second layers plus the best mold such as cloth, it can greatly improve the service life of the die (but do not use glass fiber cloth, otherwise easy to cause the layer and make the whole die scrap) 7,three-dimensional perfusion mode, generally 10-15 hours curing as well. 8, soft mold production after he finished making plaster or fiberglass jacket to support silicone soft mode note: 1, line selection: does not affect the appearance of the product position; choose the easy processing in filling the position after the selection of the die itself; easy demoulding position;Choosing the position that the product is not easy to deform can not increase the dosage of the hardening agent for the production schedule, otherwise it will greatly reduce the service life of the silica gel mould. (2). The common problems encountered in the application of mould silica gel: 1. why does the mold silica gel appear to turn the mold less times? In the process of making the mold, too much silicone oil was added, silicone oil destroyed the molecular weight of silica gel, so the mold will appear a few times less die, not durable and so on. If the small products are more complex patterns of products, with a large hardness of silica gel to mold, there will be a few times the phenomenon of turning the mold, because the silicone will be very hard to break the fragile time, easy tobreak. On the contrary, if you build a product and use the hardness of the silica gel to make the mold, the result will be unsatisfactory. Because the silicone is too soft, its tensile strength and tear strength will be reduced, the mold will be deformed, so the number of flip mode will be reduced. Mold glue itself quality is very good, silica gel is not good or bad, only suitable and not suitable. We should use the silica gel which is suitable for the hardness of the product to make the mold, it will not appear this kind of situation. 2. why mould silicon will appear burning phenomenon? As the curing agent of unsaturated resin and resin product with peroxide, when resin reaction will produce large amounts of heat, the general resin curing time is 3 minutes, so after 3 minutes to release as soon as possible, to prevent the silicon mold will not produce the phenomenon of burning mode. 3. the mold silica gel filling mold and the piece mold manufacture method: divides the piece mold or the mold operation method: carries out the vacuum silica gel to brush or the perfusion method carries on the construction. If you do die or mold with brushing, brushing off before you want to copy the product model or a layer of release agent or isolating agent, then the silicone coated on the above products (Note: must coatinguniform) wait for 30 minutes, the surface pasting a layer of gauze or the glass fiber cloth to increase the intensity, and then coated with second layers of silica gel, silica gel and dried, then do the outer mould, the outer mould can use gypsum or resin material. The operation method of filling or perfusion modes: filling or perfusion model, is used to smooth or simple products, will you want to copy the product or model, surrounded by plastic or glass plate, the pumping vacuum silicone directly into the products above, the silica gel drying after molding, out products, mold (Note: on theforming of the perfusion mould by silica gel hardness of soft to die, this release is relatively easy, does not damage the inside of the silicone rubber mold products), all above is the use and operation of the process of silicone mold. 4. why does the mold silica gel appear dry in the surface phenomenon? The silica gel belongs to condensed silica gel, which is solidified by absorbing moisture in the air. In the process of making silica gel, the water is evaporated and dried, but not transferred into the right amount of water, this phenomenon will appear. Solution: This is not a quality problem, but because there is no control of moisture, enhance the silica gel storage period, long shelf life will appear some phenomenon, as long as when using silica gel, adding 0.05% water, stir it can solve some of the situation. 5. why the mold silicone will appear tension phenomenon? Because customers in the production process of the mould, in order to reduce the viscosity of the silica gel, silica gel and silica gel is easy to operate in a large number of addition of silicone oil, which would make the silica gel become very soft, not pulling resistance, tear strength decreased, the tension variation phenomenon, resulting in the mold is not durable, short service life, turn etc. less number phenomenon. 6. why the oil will appear in the mold? Silicone mold itself is not taking oil, oil is appearing because of adding the composite silicone oil during operation (mixed silicone and white mineral oil), because white mineral oil is not oil chemical products, silicone oil. 7. why mold will produce acid and alkali resistance, anti-aging phenomenon? In the process of making silica gel molds, we recommend that customers do not have any silicone oil, if necessary,The amount of silicone oil should not exceed 5% - 10%. Becauseof the excessive amount of silicone oil will destroy the molecular weight of silica gel, so the mold will produce acid and alkali resistance, aging phenomenon is not resistant. 8. why mold silicone mold out of the surface will appear traces, stripes, not smooth and so on? This phenomenon is due to the fact that the copied product or model has not been polished or polished. Because the model or the product itself is not smooth or perfect, so the product or model to be copied, if not polished or polished, and then a good silicone mold will be unsightly, not smooth enough. There is also a situation is that, when the mold release agent, no uniform brushing will also cause the mold is not smooth. 9. wonderful use of silica gel, do you know? Silicone mold is mainly used for toys and gifts industry, craft gifts industry, furniture decoration industry, character copy, architectural decoration industry, resin handicraft industry, unsaturated resin handicraft industry, plastic toy industry, craft candles?? gift stationery industry, plaster craft gift industry,?? die manufacturing industry, industrial products,? Boli? The simulation of animal and plant products and mould making sculpture, copying Buddhist sculpture crafts and many other industries. Mainly used in toys, gifts and fine pattern for package products, mold, pouring mould products, glass, lighting, candles, figure copy making mould, large products, piece mold, reliefs, statues, craft gift making mold, shoe mold, perfusion model, sand casting. Different use of silica gel mold, specific operations are also different, to achieve what requirements, must be based on a variety of parameters specific operation.。
气凝胶[编辑]气凝胶拥有强大的隔热功能一块重2.5公斤的砖头由一块重2克的气凝胶支撑着气凝胶因散射呈蓝色气凝胶（Aerogel），也称作空气胶或是稀密封，是世界上密度仅次于全碳气凝胶（Aerographite，暂名）的人造发泡物质。
它的制造是将气体取代液体在凝胶中的位置而成，而如此做出的结果造就了拥有数种杰出特性的极轻物质。
其中最引人注目的是它良好的隔热能力。
这样的物质拥有许多俗名与昵称，如：冻结的烟雾（frozen smoke）、固态的烟雾（solid smoke）、固态的空气（solid air）、蓝烟（blue smoke）、旧金山之雾（San Fransisco fog）等，而这些都源自于他的透明性与物质中的光线散射能力。
不过，这种物质的触感却像是聚苯乙烯一般。
Samuel Stephens Kistler在1931年发明气凝胶。
而这一切是因为他与Charles Learned 之间的赌注，竞争看谁有办法将凝胶里的液体成分用气体取代却不使发泡的间壁收缩崩塌。
最后Kistler办到了。
气凝胶借由超临界干燥法（Supercritical drying）将凝胶里头的液体成分抽出。
这种方法会令液体缓慢的被脱出，但不至于使凝胶里的固体结构因为伴随的毛细作用被挤压破碎。
世界上第一个气凝胶体的主要成分是硅胶。
Kistler随后又造出了以铝、铬、氧化锡为基础物质的凝胶。
第一个碳凝胶体则迟至1980年代以后才被开发。
目录[隐藏]•1性质•2安全性•3发展•4参见性质[编辑]此物质极轻。
其密度大约为3mg/cm3仅仅为空气的三倍重。
(由Larry Hrubesh领导的LLNL实验室首先制备出世界上密度最小的CO2气凝胶)尽管气凝胶里有个胶字，但它其实是坚硬而干燥的物质，就其物理性质与胶体一点也不类似。
被称为胶是由于它的制造过程提取于凝胶。
提起指尖轻轻在凝胶表面按压一下并不会留下痕迹；如果以加重的力道按压会造成永久的凹陷；而加上足够的力量会让它如玻璃般破碎散落成块。
第21卷第1期强激光与粒子束Vol.21,N o.1 2009年1月H IGH POW ER LASER AND PA RTICLE BEAM S Jan.,2009 文章编号: 1001-4322(2009)01-0076-03三甲基硅烷化改性二氧化硅气凝胶＊陈素芬, 李 波, 刘一杨, 张占文(中国工程物理研究院激光聚变研究中心,四川绵阳621900) 摘 要: 采用六甲基二硅氮烷对二氧化硅凝胶进行疏水处理,得到了疏水性的二氧化硅气凝胶。
用红外光谱和热分析表征处理前后二氧化硅气凝胶的性质,用测量显微镜跟踪处理前后气凝胶柱在空气中直径变化。
结果表明,处理后气凝胶的表面羟基明显减少,在空气中的吸潮性大大降低,圆柱体在空气中的径向收缩率从30%降至3%。
关键词: 二氧化硅; 气凝胶; 疏水处理; 三甲基硅烷化 中图分类号: T Q127.2; T L639.11 文献标志码: A 二氧化硅由于硅原子序数适中,并且易于制成低密度气凝胶,因此在激光惯性约束聚变(inertial confine-ment fusio n,ICF)研究中获得了广泛的应用,如辐射输运研究中的输运管填充材料[1-2]。
二氧化硅气凝胶网络表面存在羟基(-OH)和未水解的乙氧基(-OC2H5)官能团。
由于-OH的存在,气凝胶易吸收空气中的水分,导致网络结构塌陷,使得气凝胶收缩,其线性收缩率可达30%[3-5]。
而ICF辐射输运研究中的输运管长度只有几百μm,且要求填充材料均匀,输运管内部填充材料微小的收缩会使材料与管壁之间产生空隙,对最终的实验结果有很大的影响。
因此需要对二氧化硅气凝胶进行疏水改性,提高其对空气中水分的稳定性,降低其收缩率[6-7]。
文献报道,利用气态介质对气凝胶进行表面疏水处理,如气相甲氧基化,得到的气凝胶疏水性能很好,但是此方法成本高,工艺复杂,因此适用范围不广泛[8]。
此外,还可在合成前体时,在正硅酸甲酯(tetrame-tho xy silane,TM OS)中混入甲基三甲氧基硅烷(M eSi(OM e)3)[9],但是该凝胶在超临界干燥时易收缩,且随着M eSi(OMe)3用量增加,气凝胶的透明度降低。
硅胶色谱填料的英文Silica Gel Chromatography Packing Material.Introduction.Silica gel chromatography packing material, also known as silica gel-based chromatographic media, plays a pivotal role in the field of chromatography and separation sciences. Chromatography is a technique that utilizes thedifferential affinity of a substance to be separatedtowards a stationary phase (packing material) and a mobile phase (solvent) to achieve separation. Silica gel, due toits unique properties, has become one of the most widely used stationary phases in chromatography.Properties of Silica Gel.Silica gel is a porous, amorphous form of silicondioxide (SiO2) with a high surface area and excellent adsorption properties. These properties make it an idealcandidate for use as a chromatography packing material. The surface area of silica gel can range from a few hundred to several thousand square meters per gram, depending on the preparation method and pore size.The pores of silica gel are primarily micropores (<2 nm), mesopores (2-50 nm), and macropores (>50 nm). The pore size distribution and surface area of silica gel can be tailored to specific applications by adjusting the preparation conditions.Silica gel is chemically inert and thermally stable, withstanding temperatures.。
鞋子结构 / 种类 / 颜色 / 资料 / 包装 / 流程等专业术语翻译1、结构帮面 -UPPER后帮 -BACK COUNTER内里 -LING大底 -OUTSOLE中底 -INSOLE中底标 -INSOLE LABEL鞋眼 -EYELET鞋眼片 -EYELET STAY鞋带 -LACE魔术扣 -VELCRO鞋舌 -TONGUE鞋跟 -HEEL靴帮 -CUT高帮 -HIGHT CUT低帮 -LOW CUT边墙 -SIDE SHOE沿条 -WELT刺绣 -EMBROIDERY扣子 -BUCKLE拉练 -ZIPPER松紧带 -ELASTIC LACE（GROE）饰片 -ORNAMENT死心 -SHANK增强带 -REINFORCE TAPE泡棉 -FOAM飞机板 -INSERTER跟皮 -HEEL COVER鞋鞍 -SADDLE满帮 -WHOLE VAMP鞋垫（中底垫皮） -SOCK LING 鞋眼前端 -VAMP鞋头 -TOE CAP套头 -TOE BOX鞋领 -COLLAR鞋腰 QUARTER滴塑片 -PLASTIC PIECE鞋统 -SHAFT滚边 -BINDING鞋后张口 -OPEN BACK大底 outsole鞋垫 sock ting质腹 bottom filler鞋跟垫片 heel pad皮泉硬纸 eather board 心纸底板 shank board 牛皮 leather仿牛皮 imitation leather 裁刀 cutting dies裁断垫皮 cutting pad布料 cloth material灯心绒 corduroy帆布 canvas反毛皮 suedePU poly urethane尼龙 nylon麻布 flax特立可得 tricot毛巾布 terry cloth泡棉 foam绸面 mesh法兰绒 flannel不织布 non woven橡胶发泡 Rubber pange 长毛里 boa毛暄 felt布里 backing加温式贴合 flame中底 insole镜面皮 putent leather小牛皮 calfskin leather小山羊皮 kidskin leather 猪皮 pigskin leather磨面皮 smooth leather压花皮 embossed leather 皮克龙 Picalon鞋头张口 open toe鞋后张口 open back鞋后密口 closed back鞋后密口 open shank鞋面 upper鞋眼前端 vamp鞋腰 quarter鞋舌 tongue鞋舌扣环 tongue coop后上片 mustache处包片 outside counter里包片 inside counter鞋领 collar装饰带 ornament鞋流 shaft of boot后跟包皮 heel cover中底边 insole binding鞋口滚边 topline binding反口领 cuff2、品名（ ITEM）运动鞋 -SPORT SHOES反绒皮 -SWEDE SHOES休闲鞋 -CASUAL SHOES 皮鞋 -LEATHER SHOES注塑鞋 -INJECTION SHOES 时装鞋 -FASHION SHOES 靴子 -BOOT拖鞋 -SLIPPER毛绒鞋 -ANIMAL SHOES（PLUSH）沙岸鞋 -BEACH SANDAL室内鞋 -INDOOR SHOES布鞋 -CANVAS SHOES凉鞋 -SANDAL3、包装（ PACKAGE）塑料袋 -POLYBAG挂钩 -HOOK彩盒 -COLOUR BOX字母扣 -NYLON STRING尺码标 -SIZE LABEL成分标 -INGREDIENT LABEL挂牌 -HANGTAG环保标 -GREEN POINT货号 -MODEL配码 -ASSORTMENT布标 -TEXTILE LABEL商标 -LOGO麦头 -MARK正麦 -MAIN MARK侧麦 -SIDE MARK双 -PAIR双数 -PAIRAGE纸箱 -CARTON箱 -CASE纸盒 -BOX纸板 -CARDBOARD包装纸 -TISSUE PAPER 干燥剂 -SILICAGEL价钱标签 -PRICE TICKET 标签 -TAG LABEL TICKET 胶带 -TEPE橡皮筋 -ELASTIC BAND层 -LAYER长度 -LENGTH立方 -CUBIC 毛重 -GROSS WEIGHT净重 -NET WEIGHT3、颜色（ COLOUR）深色 -DARK/D.淡色 -LIGHT/L.银色 -SILVER灰色 -GREY黑色 -BLACK嫩绿色 -SPRING MINT深绿色 -AUGUST GREEN浅绿色 -CITRUS GREEN草绿色 GREEN 05（LIT GREEN）鲜绿色 -DESERT WEED青绿色 -SUBLE MOSS绿色 -NEW LIGHT MINT（GREEN）水晶色 -CRYSTALLINE白色 -WHITE天蓝色 -SUN LIGHT BLUE粉蓝 -LILYSKY蓝色 -CLASSIC NAVY宝蓝 -VID TURQUOISE（ROYAL ~）蓝色 -BLUE海蓝 -NAVY水蓝色 -MEDIUM BLUE深棕色 -DERBYBROWN浅棕色 -ZONE NATURAL棕色 -CREAM SODA（BROWN）淡紫 -LILAC紫色 -PURPLE浅紫色 -DRYROSE红色 -RED嫩粉色 -LILYBLUSH铁红色 -RUST桔红色 -CORAL HAZE粉红 -TAWNYBLUSH（PINK）中国红 -MEDIUM RED（COUNTRY~）浅粉红 -PALE PINK KISS桃红 -JCP FUSHCIA桔色 -LILYORANGE金色 -PALE GOLD银色 -SILVER骨色 -TIMBER BORN(IVORY)茶色 -TAWNEY酒色 -WINE镍色 -NICKEL深咖啡 -AUTUMN MINK咖啡色 -GLOBAL BROWN冰咖色 -ICED COFFEE黄色 -SUNKING深黄色 -BUTTER CUP浅黄色 -YES YELLOW米黄色 -POLOERE黄褐色 -CAMEL 05驼色 -CAMEL米色 -BEIGE KISS大米色 -RICE象牙色 -IVORYKISS柠檬色 -LAUREL奶油色 -BUTTER MILK干草色 -PALE HAY烟色 -TAUPE SMOKE原木色 -SANDAL WOOD 卡其色 -KAKI沙色 -TOASTED ALMOND 4、资料 (MATERIAL)皮 -LEATHER软皮 -CASTING LEATHER 反绒皮 -SWEDE LEATHER猪皮 -PIG SKIN橡胶 -RUBBER塑料 -PLASTIC注塑 -INJECTION纺织布 -TEXTILE打蜡皮 -BURNISHED LEATHER 帆布 -CANVAS弹力布 -LYCRA水牛皮 -BUFFALO HIDE牛皮 -COW LEATHER纳帕 PU-NAPU拉米 -LAMY合成革 -SYNTHE PU牛巴 -PU NUBOCK网布 -MESH整片底 -UNIT SOLE EVA底 -EVASOLE钉子 -NAIL布类 -FABRIC麻布 -JUTE胶 -GLUE/CEMENT皮克隆 -PICALON特丽可得 -TRICOT天皮 -TOP LIFT/HELL LIFT打包带 -PE TAPE6、鞋类器具名称钳子 -PINCER布尺 -TAPE前帮机 -TOE LASTING MACHINE 剪刀 -SCISSORS输送带 -CONVEROR针车 -STITCHING MACHINE毛刷 -BRUSH斩刀 -CUTTING DIE包装机 -PACKING MACHINE铁捶 -HAMMER尺 -RULER后帮机 -COUNTER LASTING M~ 空气枪 -AIR GUN鞋拔 -SHOE HORN裁断机 -CUTTING MACHINE打钉机 -NAILING M~模型 -MOLD压底机 -SOLE PRESS MACHINE硬度计 -HARDNESS TESTER厚度计 -THICKNESS TESTER拉力机 -TENSILE STRENGH TESTER 温度计 -MOISTURE TESTER7、制鞋过程裁断 -CUTTING针车 -STITCHING成型 -LASTING攀鞋 -WRAPPING入前套 -LAYTOE BOX上糊 -CEMENTING后帮 -COUNTER LASTING前帮 -TOE LASTING拔钉 -PULL-OUT STAPLE削皮 -SKIVING洁净 CLEAN贴底 -SOLE LAYING修边 -FOLDING加热 -HEATING冷却 -COOLING入楦 -PUT-ON LAST除楦 -TAKE-OURT LAST贴鞋垫 -SOCK LAYING包装 -PACKING磨粗 -BUFF打蜡 -WAXING8、定单应用定单号码 -ORDER NO.定单日期 -DATE OF ORDER交货日期 -DELIVERYDATE工厂号码 -FACTORYNO.型体 -STYLE客户库存号码 -CUST. STOCK NO. 制造者 -MFG装船日期 -SHIPPING DATE客户定单号码 -CUST. ORDER NO. 进货港口 -PORT OF ENTRY9、鞋类弊端发霉 -GET MILDEW碎屑 -CHIP纸样错了 -WRONG PATTERN太钝 -TOO DULL起毛 -HAIRY鞋面皱折 -VAMP WRINKLE不配双 -NOT IN PAIR鞋面裂开 -VAMP SPLIT OFF线不均匀 -STITCHING NOT EVEN鞋面翻开 -VAMP OPEN UP跟不正 -HEEL NOT STRAIGHT中底发角 -ANGLE ON INSOLE裁断错误 -WRONG CUTTING贴底不正确 -SOLE LAYING NOT PROPER 鞋不均匀 -WRAPPING NOT EVEN后带太高 / 低-BACKSTRAP TOO HIGH/LOW 攀脱胶 -CEMENT COMES OFF大底不平 -OUTSOLE NOT SMOOTH跟粘上胶 -CEMENT ON HEEL接着力不够 -CEMENT NOT GOOD洁净度不够 -CLEANESS NOT ENOUGH鞋头陷下去 -TOE BROKEN DOWN钉子露出来 -STAPLE COMESOFF颜色不配合 -COLOUR NOT MATCHINE 不照记号本 -STITCHING NOT ON MARK 制鞋过程即品管检验应用术语:浸水 SOAKING浸水试验 WATER TREATMENT TEST烘干 DRYING真空成型法取样板VACUUM FORMING 级放 GRADING耗电量 POWER CONSUMPTION记号码 NOTCH配方 FOUMULA针鞋跟 HEEL ATTACHING针孔记号 PRICK MARK针距 STITCH LENGTH马靴脚背早先定型CRIMPING高波接合 HEAT SETTING密接缝 CLOSED SEAM斩刀截断 PRESS CUTTING清理鞋子 CLEAN混杂 COMPOUND产前问题解析LINE UP硫化 VULCANIZE硫化促进剂 VULCANIZING ACCELERATOR挪动、流动 MIGRATION第一次上糊 FIRST CEMENTING第二次上糊 SECOND CEMENTING粗线车缝 CABLE STITCHING粗线缝 ROPE STITCHING组件 COMPONENT脱模剂 MOLD RELEASE脱线 LAST SLIPPING袋翻法 BAGGING设备 EQUIPMENT通气孔 VENTILATION连环车缝法 CHAIN STITCH着地点 TREAD POINT着色 PIGMENTATION贴合内里 CEMENTED LING贴商标 BRANDING贴糊插死心 LAYING＆CEMENTING ON WELT＆SHANK贴胶带法取样板 TAPING FORME开饰洞 CUT OUT圆形小组式生产系统RINK SYSTEM微办理控制 MICROPPOCESSOR CONTROL感觉器 SENSOR溶剂型接着剂SOLBENT BASED CEMENT碎屑 CHIP绑标签 TYING试片 TEST PIECE钳帮部位 LASTING ALLOWANCE楦盖分别式鞋楦SEPARATE LAST楦头底盘中央线LAST BOTTOM CENTRAL LINE 楦头长度 STICK LENGTH滚条接缝 PIPED SEAM, PING滚边 BINDING, CORDING蒸湿鞋面 MULLING制程 PROCESSING模造中插 MOULD WEDGE模铸成型结构MOULDED CONSTRUCTION皱纹 WRINKLE线头 CHANNEL胶水表层凝结现象CEMENT SKINNING胶着力试验 ADHESION TEST胶渍 GLUE调整 ADJUST轮廓 CONTOUR轮边 WELTING ROLLING铝楦底孔供钉中底用TACK HOLE鞋底边沿高压磨光EDGE SETTING鞋面洞 PERFORATION鞋面折皱 PINTUCK鞋跟外观 HELL WEDGE APPEARANCE 鞋跟动稽试验HEEL IMPACT TEST操作 OPERATION整饰 FINISH磨、檫洗 SCRUB磨鞋头 TOE ROUGHING磨鞋边 SHOE EDGE GRINDING荧光 FLUORESCENT LIGHT退色试验 COLOR FADDING TEST压边 SIDE PRESSING检验 INSPECT查考据书 CERTIFICATE OF INSPECTION 缩进去 PINCH IN缝细线 FINE STITCHING缝线 SEWING THREAD缝线功能 STITCHING FUNCTION双针 DOUBLE NEEDLE药水办理 PRIMING露边接缝 OPEN SEAM曲折性 FLEXIBILITY曲折试验 BENDING TEST叠合接缝 LAPPED SEAM变黄、黄变 TURN YELLOW制鞋过程即品管检验应用术语:V 型补强车线 VEEING入中底于楦上INSOLE STAPLING ON LAST入前后套及上糊TOE BOX LAYING＆COUNTER POCKET CEMENTING 入楦 PUT-ON LAST入楦成型结构SLIP LASTED CONSTRUCTION入鞋垫 SOCK LAYING上套板纸团 PUTTING CARBOARD＆TISSUE PAPER大底削薄 REDUCING工作单 WORK TICKET中底削斜 LEVELING中庸样板 MEAN FORME中间线 CENTRALINE内里印刷 COUNTER POCKET STAMPING 内线车底法 MCKAYPROCESS切割条状槽 SLOTTING尺寸记号 SIZE NOTCH尺码的分段 SIZE RANGES尺码量尺 SIZE STICK比重 SPECIFIC GRAVITY毛边 FUSSY水平基础 BASE PLANE水溶性接着剂WATER BASED CEMENT 片皮 SPLITING加沿条拉线 WELTED SEAM加硫罐 PRESSURE VESSEL加热定型 HEAT SETTING加热减量测试WEIGHT LOSS BYAGEING 半成品 SEMI-PRODUCT去除溶剂 REMOVE SOLVENT平头拉线 BUTTED SEAM打空气钉 STAPLING打钉饰扣 HOLE PUNCHING＆BUCKLE INSERTING 打粗磨粗 ROUGHING打鞋眼孔 EYELET PUNCHING打磨 WAXING生产线 PRODUCTION LINE皮边整烫 BURNISHING仿古铜色办理ANTIQUE全铁片楦头 FULL IRON BOTTOM吉利领口 GHILLIE TOPLINE吊里 LOOSE LING在制品 WORK-IN-PROGRESS（WIP）成品整理 TREEING成型、组合 ASSEMBLY色污染 STAIN西班牙式缝法SPANISH MOCCASIN伸长率试验 ELONGATION TEST伸展性 TENSIBILITY冷冻定型 CHILLING吸水性试验 WATER VAPOR ABSORPTION TEST 抗老化剂 AGE RESISTER折边 FOLDING车外线 OUTSIDE WELT STITCHING 车缝记号 STITCH MARKING底部成型 BOTTOM SIDE FORMING 底边上墨 EDGE INKING拉紧 STRAIN，TAUT拉压力测试 TENSILE FORCE TEST 拔钉 NAIL EXTRACTING拔楦 PULL-OUT LAST抽条 ATRIPING易燃品 COMBUSTIBLE法国式滚边 FRENCH CORDING物料控制 INVENTORYCONTROL直接射出法 DIRECT INJECTION花缀缝 FANCYSTITCHING表面研磨 SURFACE SCOURED表面涂饰 DRESSING金属管 FERRULE保持形状 RETAIN THE SHAPE削薄 SKIVE前段中线 FOREPART LINE厚度 THICKNESS后跟中央接缝CENTRAL SEAM后跟缝线高度BACK SEAM TACK HEIGHT流程部署 LAYOUT活性剂 ACTIVATOR相对样品 COUNTER SAMPLE耐硫化试验 ACTION OF SULPHUR VAPOR TEST耐滑试验 SLIP RESISTANCE TEST耐烧试验 CRACKING TEST耐压试验 COMPRESSION TEST英式缝法 ENGLISH MOCCASIN更正 MODIFY修边 TRIMMING剥离试验 PEELING TEST原厂拜托制造ORIGINAL EQUIPMENT MANUFACTURE（OEM）10、"贸易知识批发 -WHOLE SALE积蓄 -HOARD成本价 -COST PRICE行家 -ADEPT发票 -INVOICE大批生产 -MASS PRODUCTION低价 -SALE验货员 -INSPECTOR检验员 -INSPECTION SHEET开发票 -BILLING征收 -COLLECTION航运公司 -SHIPPING COMPANY产量 -OUTPUT畅销 -DUMPING装船文件 -SHIPPING DOCUMENTS 库房 -WARE HOUSE买卖兴旺 -BOOM上等货 -TOP QUALITY正牌货 -STANDARD破产 -BANKRUPT航空邮包 -AIR PARCEL POST报价 -OFFER已装船 -ON-BOARD部分损失 -PARTIAL LOSS收款人 -PAYEE流程 -PROCESS装船日期 -SHIPPING DATE索赔 -CLAIN结关日 -CLEAR DATE装船通知 -SHIPPING ADVICE佣金 -COMMISSION收货人 -CONSIGNEE交货期 -DELIVERYDATE复查 -DOUBLE CHECK货柜 -CONTAINER装卸码头 -SHIPPING DOCK出仓 -DELIVERYFROM GODOWN确认样品 -COMFIRMATION SAMPLE（CFM SPL）当心轻放 -HANDLE WITH CARE即期信誉证 -SIGHT LETTER OF CREDIT试穿样品 -FITTING SAMPLE（FITTING SPL）远期信誉证 -USANCE LETTER OF CREDIT可撤消信誉证 -REVOCABLE LETTER OF CREDIT不行撤消信誉证 -IRREVOCABLE LETTER OF CREDIT 可转让信誉证 -ASSIGNABLE LETTER OF CREDIT不行转让信誉证 -UNASSIGNABLE LETTER OF CREDIT 11、"其余确认 -CONFIRM/CFM主要 -PRIMARY次要 -MAJOR尺寸 -INCH牛仔布 -DENIM药水 -PRIMER二榔皮 -SPLIT LEATHER泡棉 -FOAM海绵 -SPONG生产线 -PRODUCTION LINE底边 -SOLE EDGE滚边 -BINDING底台包皮 -PLATFORM COVER饰片 -OVERLAY拒绝 -REJECT质量管理 -QUALITYMANAGEMENT 国际标准组织 -ISO记录 -RECORD外箱贴纸 -CARTON LABEL制鞋流程名称Cutting 裁断Wrapping 攀帮Counter Lasting后帮Pull-Out Last拔楦Tissue Paper塞纸Cleaning 洁净Stamp 烫金Sole Press压底Grind Edge Of Sole磨鞋边Insole Staple On Last入中底于楦上Finish 磨光末道漆Sitching 针车Primering 药水办理Forepart Lasting腰帮Loose Thread剪线头Toe Skiving磨鞋头Sock Laying塞鞋垫Mold Prevention 防霉Gluing 贴合Poly(Plastic)Bag塑胶袋Heating&Drying 加热烘干Vulcanized 加硫Assembling 成型Cementing 上糊Pull Out 拔钉Packing 包装Waxing 打蜡Sole Laying贴底Skive 削薄Toe Lasting前帮Folding 拗边Fixing 整理Cooling 冷却Adjust 调整Lasting 入楦Tag 标签Marking 标示Volatilication 挥发Pincer 钳子Air Gun 空气机Stapler 订书机Freezer 冷冻箱。
SiO 2气凝胶疏水改性方法研究进展1刘明龙，杨德安天津大学材料学院先进陶瓷与加工技术教育部重点实验室，天津 (300072)E-mail ：m.dragonliu@摘 要：文章综述了对SiO2气凝胶进行疏水改性的技术的最新研究进展，介绍了溶剂置换-表面改性法，直接表面改性法和联合前驱体法三种改性方法的改性机制及各种常用的表面改性剂，并从所制得的最终样品的性能、成本、实用性等方面进行了比较，从而总结出一种较经济实用的制备方法。
关键词：SiO2气凝胶；纳米多孔材料；溶胶-凝胶；疏水型；绝热材料1本课题得到国家自然基金委重点基金项目(10232030)，天津大学先进陶瓷与加工技术教育部重点实验室 (x06050)的资助。
SiO 2气凝胶是一种具有独特的纳米多孔网络结构的轻质材料，因其极低的折射率、热导率和介电常数，高的比表面积和对气体的选择透过等特性，而在绝热材料、隔音材料、过滤材料以及催化剂载体等众多领域有着广泛的应用前景，尤其在作为高性能绝热材料方面受到了普遍关注。
由于通常方法制备出的SiO 2气凝胶内表面有大量的硅羟基存在，它们不仅会因缩聚而引起凝胶块体产生额外收缩，还能吸附空气中的水分而使气凝胶开裂破碎，严重影响了气凝胶的声、光、电、热、力学等性能，限制了它的应用场合。
因此，只有设法对制备的气凝胶进行疏水改性，增加它在空气中的稳定性和使用寿命，另外，再配合一系列增强、增韧措施，以制成纳米多孔绝热复合材料，才能在保温工程中发挥出它的真正作用。
1. SiO 2气凝胶的疏水改性及原理SiO 2气凝胶通常是由溶胶-凝胶法制备的，开始制得的醇凝胶固态骨架周围存在着大量溶剂（包括醇类、少量水和催化剂），要得到气凝胶，必须通过干燥以去掉其中的溶剂。
然而，在溶剂干燥过程中，由于凝胶纳米孔内气-液界面间产生表面张力，导致邻近的Si-OH 基团发生缩聚反应，形成Si-O-Si 键，从而产生了不可恢复的收缩；另外，这些Si-OH 基团还可以吸附空气中的水分，使表面张力增大，从而使气凝胶块体开裂破碎。
Processing of low-density silica gel by critical point drying orambient pressure dryingValerie nd,Thomas M.Harris *,Dale C.TeetersDepartment of Chemistry and Biochemistry,University of Tulsa,600S.College Ave.,Tulsa,OK74104-3189,USAReceived 5July 2000;received in revised form 20February 2001AbstractVarious methods for the production of low-density silica from silica gel were studied.The silica gel was prepared by the `two-step'sol±gel method.The `DSB process'(developed by Deshpande,Smith and Brinker),which takes the gel through solvent exchange,reaction with trimethylchlorosilane (TMCS)and ambient pressure drying (APD),was thenapplied.This processing provided a greater total pore volume,and more mesopores with diameters >50 A,than critical point drying (CPD),the conventional method for producing an aerogel.The high porosity was found to be due pri-marily to the solvent exchange step;in fact,the reaction with TMCS reduced the porosity.Reaction of the gel with trimethylmethoxysilane (TMMS)in the mother liquor (ethanol/water)provided higher pore volumes than the DSB process.This extra porosity may be attributed to poor wetting of the polar solvent in contact with the surface made hydrophobic through reaction with the TMMS;thus,the capillary forces that cause the gel to shrink are reduced.Finally,it was discovered that some loss of porosity occurs when CPD is conducted with carbon dioxide;speci®cally,the pressure pulse that occurs when the CPD cell is initially ¯ooded with this liquid can damage the structure of the silica network.Ó2001Elsevier Science B.V.All rights reserved.1.IntroductionAerogel materials exhibit very high surface area and signi®cant nanoporosity.A number of appli-cations for these materials have been explored [1].The use of silica aerogels as high e ciency thermal insulation has received the greatest attention [2,3].The conventional method of producing an aerogel,discovered by Kistler [4]in 1931,involves removal of the solvent from a `wet gel'under supercritical conditions.This technique,referred to as critical point drying (CPD),avoids the build up of tensilestresses that cause the polymeric network to col-lapse as the vapor±liquid interface recedes into the gel.Since CPD requires the use of an autoclave,the technological utilization of aerogels has lagged far behind their development in the laboratory.However,a discovery by Deshpande,Smith and Brinker [5]involving silica aerogels may ®nally allow the full commercial potential of these ma-terials to be realized.In the `Deshpande,Smith and Brinker (DSB)process',the wet gel is washed with an aprotic solvent,reacted with trimethyl-chlorosilane (TMCS)and then dried at ambient pressure.This treatment minimizes shrinkage of the gel,through a reduction in the surface tension of the solvent and the contact angle between the solvent and the surface of the silica network[6].Journal of Non-Crystalline Solids 283(2001)11±17/locate/jnoncrysol*Corresponding author.Tel.:+1-9186313090;fax:+1-9186313404.E-mail address:thomas-harris@ (T.M.Harris).0022-3093/01/$-see front matter Ó2001Elsevier Science B.V.All rights reserved.PII:S 0022-3093(01)00485-9In addition,as the last trace of solvent evaporates from the gel the shrunken silica network springs back to its original dimensions.This behavior in-dicates that the TMCS eliminates residual silanol groups which are otherwise capable of forming siloxane bridges across the pores and locking the network into the shrunken con®guration[7].In the DSB process,the wet gel initially pos-sesses an ethanol/water mixture as the solvent(the mother liquor).Since TMCS is chemically unsta-ble in this solvent,the DSB process includes a solvent exchange step in which the gel is washed with several portions of an inert solvent.In the present study the feasibility of utilizing azeotropic distillation to exchange the solvent,and substi-tuting a more stable silylating reagent for TMCS, were considered.In the course of this work fur-ther insight into the production of aerogels through ambient pressure drying(APD)has been gained.2.Experimental methodologyThe wet gel utilized throughout this study was prepared by the`two-step process'developed by Brinker and co-workers[8,9].The®rst step in-volves acid(hydrochloric)catalysis of the hydro-lysis of tetraethyl orthosilicate(TEOS).The second step involves condensation polymerization of the silanol groups resulting from the hydrolysis reactions.The condensation reaction is inhibited by the acid added in the®rst step;thus,the second step includes the addition of ammonium hydroxide to neutralize the acid.The®rst step was conducted in a reaction vessel (with water-cooled condenser)placed on top of a stirrer/hot plate.The reaction mixture,which in-cluded244ml of TEOS(Aldrich,98%pure),244 ml of absolute ethanol(Pharmco),19.6ml of de-ionized water and0.8ml of1.0M hydrochloric acid(Fisher Scienti®c),was heated at60°Cfor2h. The resultant`acidic sol'was then stored in a polyethylene bottle in a freezer(À20°C).In the second step of the process20ml of the acidic sol were combined with2.0ml of0.50M ammonium hydroxide solution(Fisher Scienti®c).The mixture was then placed in a sealed polyethylene container and aged for24h at50°Cin a water bath.Gela-tion occurs within minutes at this temperature. To exchange the solvent in the gel by`washing', the block of gel was contacted with three50ml portions of ethanol,followed by two50ml por-tions of an aprotic solvent(typically heptane).The ethanol washes were conducted at50°Cfor1h, while the aprotic solvent washes were for2h at 50°C.To exchange the solvent by azeotropic dis-tillation,the gel was broken up and transferred to a distillation apparatus(equipped with a Dean-Stark trap and addition funnel)containing75ml of toluene.The contents of the¯ask were then heated slowly to boiling.During the distillation, 25ml of toluene was added from the addition funnel each time25ml of distillate were recovered. Complete removal of the ethanol and water was indicated by a constant temperature of110°C,the boiling point of toluene.The®nal step of the DSB process involves reaction of the silica gel with TMCS.Additional inert solvent was added to the22ml of solvent-exchanged gel,and then3.0ml of TMCS(Aldrich, 98%)was added;this quantity corresponds to %0.55moles per mole of silicon in the silica network.The reaction was allowed to proceed for20h at50°C.An alternative reagent, trimethylmethoxysilane(TMMS)(Aldrich,98%) was also evaluated in this study.Since this com-pound is relatively stable in ethanol and water, solvent exchange did not need to be carried out prior to its reaction with the silica gel.Two di erent drying procedures were em-ployed.In both cases,the gel was®rst broken up into small chunks.For APD,the chunks were simply placed in a fume hood overnight.For CPD, which was conducted in a Polaron Jumbo cell, %100ml of solvent were added to the cell before the gel,to prevent inadvertent APD prior to the CPD process.The cell was then closed and cooled to18°C.Next,liquid carbon dioxide was allowed to®ll the remainder of the cell,and then displace the solvent through a valve at the bottom,while the cell was cooled to18°C.The liquid CO2supply was then shut o and a small vapor space was allowed to form at the top of the cell.Next,the cell was heated to38°C(in increments of2°C,at8min intervals),which converts the carbon dioxide tond et al./Journal of Non-Crystalline Solids283(2001)11±17the supercritical state.Finally the cell was vented slowly.Under these conditions the CO2escapes from the gel without generating a vapor±liquid interface.After APD or CPD,the gels were calcined at 500°Cfor15min.As indicated by Fourier-trans-form infrared spectroscopic analysis,this heat treatment completely evaporated the residual sol-vent and combusted all organic functional groups from the silica network.The surface area and porosity of the resultant materials were then de-termined through nitrogen physisorption analysis, using an Autosorb-1(Quantachrome).The5-point BET calculation was used to determine the surface area.The BJH model and the desorption isothermdata to calculate the cumulative pore volume as a function of pore diameter[10].Smith et al.[7]note that the surface tension of liquid nitrogen is not zero,and thus some shrinkage of an aerogel may occur during measurement of the desorption iso-therm.However,the calcination treatment em-ployed in this study should strengthen the silica network,and thus minimize this source of error. Several of the samples described in this report were replicated in order to assess the repeatability of the processing(as well as that of the surface area and pore volume determination).For exam-ple,three samples that were reacted with TMMS and then subjected to APD provided surface area values with a relative standard deviation(RSD)of 5.6%,and total pore volume values with an RSD of6.2%.3.ResultsPorosity data for silica gel resulting from the two-step process and subjected to APD or CPD are presented in Fig.1.APD of this gel yields a material with signi®cant porosity(0.68cm3/g of total pore volume).However,this porosity corre-sponds primarily to micropores(pore diameter <20 A)and small mesopores(20±50 A).When the gel is subjected to CPD the total pore volume is not substantially higher,but nearly half of this volume corresponds to intermediate mesopores (50±100 A)and large mesopores(>100 A).Porosity data for material resulting from the DSB process are presented in Fig.2.In this pro-cess the gel is subjected to washing with an aprotic solvent,reaction with TMCS and then APD. Hexane was employed in the washing step for the ®rst sample,while heptane was used for the sec-ond.In both cases the pore size distribution is essentially identical to that provided by CPD of the wet gel(Fig.1),but the total pore volume is actually greater(25%for hexane-washed,7%for heptane-washed).The e ect of the solvent washing step of the DSB process was examined.Surprisingly,APD after solvent washing alone provided a totalporeFig.2.Pore volume distribution data for gels subjected to APD:(a)washed with hexane,reacted with TMCS;(b)washed with heptane,reacted with TMCS;(c)washed with hexane only;(d)washed with heptane only.SA±surface area;TPV±total porevolume.Fig.1.Pore volume distribution data for silica gel(ethanol±water solvent)subjected to APD or CPD.SA±surface area; TPV±total pore volume.nd et al./Journal of Non-Crystalline Solids283(2001)11±1713volume that is signi®cantly higher than that re-sulting from the DSB process (Fig.2),as well as that resulting from CPD of the gel with its mother liquor (Fig.1).This increase corresponds primarily to a higher population of intermediate mesopores.Hexane provides more pore volume than heptane.The feasibility of substituting azeotropic distil-lation with toluene for solvent washing was con-sidered.It can be seen in Fig.3that when the gel is subjected to distillation in toluene,reaction with TMCS and then APD,a pore volume distribution nearly equal to that provided by the DSB process (Fig.2)is observed.Also presented in Fig.3are porosity data for a gel subjected only to toluene distillation and then APD.This treatment pro-vided signi®cantly more large and intermediate mesopores in comparison to the sample reacted with TMCS.However,toluene distillation alone did not provide as much total pore volume as hexane washing alone (Fig.2).Also considered in this study was the substitu-tion of a di erent silylating reagent for the TMCS employed in the DSB process.TMMS provides a potential advantage over TMCS in that it is more stable in ethanol or water;this allows the surface modi®cation reaction to be conducted in the mo-ther liquor,potentially eliminating the solvent ex-change step.Porosity data for a gel subjected to reaction with 0.55mol of TMMS (per mole of TEOS)and then APD are presented in Fig.4.Reaction conditions were identical to those em-ployed with TMCS (20h at 50°C).This material exhibits a higher total pore volume than that provided by the DSB process (1.05vs 0.96cm 3/g),due primarily to a larger volume of intermediate mesopores.It is important to emphasize that sol-vent exchange is not necessary,and was not uti-lized,to produce this material.In a related series of experiments gels were treated with increasing amounts of TMMS.It was observed that the vol-ume of large mesopores increased further as the amount of TMMS was increased to 0.82mol (per mole of TEOS).To examine the issue of wettability with respect to the TMMS-reacted surface,a gel treated in this manner was washed with heptane prior to APD.The porosity data for this material are also pre-sented in Fig.4.It can be seen that the additional solvent washing reduced the total pore volume only slightly;however,there was a substantial shift in the pore volume from large to intermediate mesopores.TMMS-treated gels were also subjected to CPD and a `hybrid'drying treatment.The porosity data for the materials resulting from these treatments are also presented in Fig.4.The gel subjected to CPD exhibited a lower pore volume than the gel subjected to APD.In comparison to the TMMS-treated gel that was subjected directly to APD,there was a substantial loss of pore volumecor-Fig.3.Pore volume distribution data for gels subjected to APD:distilled with toluene,reacted with TMCS;distilled with toluene only.SA ±surface area;TPV ±total porevolume.Fig.4.Pore volume distribution data for silica gels:(a)reacted with TMMS,subjected to APD;(b)reacted with TMMS,wa-shed with heptane,subjected to APD;(c)reacted with TMMS,subjected to CPD;(d)reacted with TMMS,exposed to liquid CO 2,subjected to APD.SA ±surface area;TPV ±total pore volume.nd et al./Journal of Non-Crystalline Solids 283(2001)11±17responding to intermediate mesopores.In the hy-brid treatment the gel was subjected to initial ¯ooding with CO2in the CPD cell,but was then removed from the cell and subjected to APD.The total pore volume and pore size distribution pro-vided by this processing were nearly identical to those provided by CPD alone.4.DiscussionAPD of the`two-step'silica gel produced in this study provides a material with a total pore volume nearly equal to that provided by CPD of this gel (Fig.1).However,with CPD much more of this pore volume corresponds to intermediate mesop-ores(50±100 A)and large mesopores(>100 A).It may be concluded that the larger mesopores shrink irreversibly to smaller mesopores during APD. The observation that the pores do not shrink all the way into the micropore range is probably due to this gel being relatively sti ,as a result of using base in the second step of the processing,and of aging at50°Cinstead of room temperature. When applied to the two-step gel employed throughout this study,the DSB process provides a pore size distribution that is essentially identical to that provided by CPD.However,the total pore volume provided by the DSB process was actually greater(by25%).Thus,the DSB process is not just a viable alternative to CPD;it can provide more mesoporosity than CPD with some precursor silica gels.This unexpected result is at least partly due to the relatively sti gel used here.The importance of the solvent washing step in the DSB solvent was investigated.Washing with an aprotic solvent followed by APD(Fig.2)pro-vided a total pore volume signi®cantly higher than that for the gel subjected to APD directly(Fig.1). Deshpande et al.[11]report that utilizing a solvent with a lower surface tension reduces shrinkage of the gel during APD.The results of the present study are consistent with this observation.The washing procedure used in the present study re-sulted in a mixture of hexane and ethanol in which the hexane content did not exceed75vol.%.The surface tensions of the pure liquids are0.0184and 0.0227N/m at20°C,respectively[12],so the sur-face tension of the mixture is%0.02N/m throughout the drying process.The mother liquor of the gel contains%15%water(added to promote hydrolysis during the sol±gel processing).Since the gel is washed with ethanol before being washed with hexane,the concentration of water should be quite low.However,this residual water will be the last solvent to evaporate during APD.Since the surface tension for pure water is0.073N/m,the surface tension of the solvent in the gel during the last stages of APD could be signi®cantly higher than0.020N/m.It was noted above that washing with an aprotic solvent followed by APD provided a total pore volume signi®cantly higher than that for the complete DSB process(Fig.2).From this it may be concluded that reaction with TMCS actually causes a loss of porosity.Hydrochloric acid is a by-product of the reaction between TMCS and the silica gel,and acid catalyzes the hydrolysis of sili-con alkoxide groups(including the trimethylsiloxy group).Thus,it is conceivable that the elimination of silanol groups is not complete under these conditions,and that further condensation poly-merization limits the`spring-back'that would otherwise occur in the last stages of APD. Another possible explanation for the lower porosity of the gels treated with TMCS relates to the contact angle between the solvent and the surface of the silica network.Greater shrinkage stresses are expected to develop when the solvent wets the silica network more e ectively,as mani-fested by a lower contact angle[6].Stein et al.[13] have demonstrated that reaction of silica with TMCS provides a hydrophobic surface that is ef-fectively wetted by non-polar organic solvents.In contrast,hexane(or heptane)should not wet the hydrophilic surface of the original silica gel(i.e., before reaction with TMCS);thus,less shrinkage would be expected when the gel is subjected only to solvent exchange and APD.The feasibility of substituting azeotropic distil-lation with toluene for solvent washing in the DSB process was also considered in this study.When this substitution was made(Fig.3),a pore volume distribution nearly equal to that provided by the DSB process(Fig.2)was observed.However, when the gel was subjected only to toluenend et al./Journal of Non-Crystalline Solids283(2001)11±1715distillation and APD,signi®cantly more large mesopores were preserved.This may result from a strengthening of the silica network during the distillation,which involves a much higher tem-perature(110°Cvs50°C)than that employed in the gel processing or the DSB process.Alterna-tively,this e ect may be due to more complete removal of the ethanol and water from the gel.In either case,azeotropic distillation is a convenient substitute for the time-consuming and wasteful solvent washing procedure.Also considered in this study was the substitu-tion of a di erent silylating reagent for the TMCS employed in the DSB process.The motivation for this search was the desire to conduct the reaction in the mother liquor of the gel,thus allowing elimination of the solvent exchange step alto-gether.Material produced with TMMS(Fig.4) exhibited a higher total pore volume than that from the DSB process(Fig.2),due primarily to a higher population of intermediate mesopores.In light of the discussion above the greater porosity provided by the TMMS-based processing may be attributed to two factors.First,since the reaction of TMMS with silica gel produces methanol in-stead of hydrochloric acid as a by-product,more complete elimination of silanol groups on the silica network would be expected.Secondly,the reaction with TMMS renders the surface of the silica net-work hydrophobic,which in this case is poorly wetted by the polar mother liquor.To test this last issue a gel reacted with TMMS was washed with heptane before being subjected to APD.The sub-stantially lower population of large mesopores in this material(Fig.4)belies greater shrinkage under these conditions,which is consistent with better wetting of the hydrophobic surface by the non-polar solvent.At the outset of this project it was assumed that CPD would provide the highest pore volumes. This assumption proved to be incorrect;almost all of the APD-based processing schemes provided higher total pore volumes,and greater populations of intermediate and large mesopores,than CPD-based processing.As noted above,very high pore volumes will not be obtained with a relatively sti gel,such as the one employed throughout this study.On the other hand,the head-to-head com-parison between APD-based and CPD-based processing in this study does point out that partial, irreversible shrinkage of the silica network can occur during CPD.Upon re¯ection it seemed likely that the gel was being damaged during the initial¯ooding of the CPD cell with the liquid carbon dioxide,which raises the pressure abruptly to a value in excess of850psi.To test this hy-pothesis,TMMS-treated gels were subjected to CPD or a hybrid drying treatment.The gel sub-jected to CPD exhibited less porosity than that subjected to APD(Fig.4).The porosity provided by the hybrid processing was nearly identical to that provided by CPD alone.Taken together, these results con®rm that the gel structure can be damaged by the pulse of high-pressure CO2at the beginning of the CPD process.5.Summary and conclusionsThe conventional means of producing silica in the aerogel form is to subject silica gel to CPD. Unfortunately,CPD is much less practical than APD.In this study,the DSB process(®rst reported by Deshpande,Smith and Brinker),which involves exchange of the mother liquor with an aprotic solvent,reaction with TMCS and then APD, provided a greater total pore volume,and more mesopores with diameters>50 A,than CPD. Surprisingly,the high porosity was found to be due primarily to the solvent exchange step;sub-sequent reaction of the gel with TMCS,which creates a hydrophobic surface on the silica net-work,actually reduces the porosity.This e ect is due to either the catalysis of additional hydrolysis by hydrochloric acid,a by-product of the TMCS reaction,or by enhanced wetting of the non-polar solvent on the hydrophobic silica surface. Reaction of the gel with another silylating re-agent,TMMS was also considered in this study. This reagent is stable in the mother liquor;thus, reaction of the gel with TMMS need not be pre-ceded by solvent exchange.APD of TMMS-trea-ted gels provided signi®cantly higher porosity than the DSB process.This discovery has important commercial consequences;silica aerogel can now be produced without the need for CPD(whichnd et al./Journal of Non-Crystalline Solids283(2001)11±17requires a high-pressure cell)or solvent exchange (which is time consuming and generates much solvent waste).The extra porosity provided by TMMS-treated gels is consistent with the expla-nations provided above for the decrease in pore volume associated with the use of TMCS.In theory no process that concludes with APD should provide porosity in excess of that provided by CPD.However,this was commonly observed in the present study.Subsequently it was discovered that some loss of porosity does occur when CPD is conducted with carbon dioxide as the supercritical ¯uid;damage to the silica network occurs during the initial¯ooding of the CPD cell,which abruptly raises the pressure to850psi.AcknowledgementsThis work was funded by the National Science Foundation,under grant number DMR-9971534. One of us(T.M.H.)would also like to thank C.J. Brinker of Sandia National Laboratories for sponsorship of a sabbatical featuring work with the DSB process.References[1]M.Schmidt,F.Schwertfeger,J.Non-Cryst.Solids225(1998)364.[2]D.M.Smith,A.Maskara,U.Boes,J.Non-Cryst.Solids225(1998)254.[3]D.Buttner,E.Hummer,J.Fricke,in:J.Fricke(Ed.),Aerogels,Springer,Berlin,1985,p.116.[4]S.Kistler,Nature127(1931)741.[5]R.Deshpande,D.Smith,C.J.Brinker,US Patent No.5,565,142,issued1996.[6]D.M.Smith,G.W.Scherer,J.M.Anderson,J.Non-Cryst.Solids188(1995)191.[7]D.M.Smith,D.Stein,J.M.Anderson,W.Ackerman,J.Non-Cryst.Solids186(1995)104.[8]C.J.Brinker,K.Keefer,D.Schaefer,C.Ashley,J.Non-Cryst.Solids48(1982)47.[9]C.J.Brinker,K.Keefer,D.Schaefer,R.Assink,B.Kay,C.Ashley,J.Non-Cryst.Solids63(1984)45.[10]E.P.Barrett,L.G.Joyner,P.P.Halenda,J.Am.Chem.Soc.73(1951)373.[11]R.Deshpande,D.Hua,D.Smith,C.J.Brinker,J.Non-Cryst.Solids144(1992)32.[12]R.C.Weast(Ed.),CRC Handbook of Chemistry andPhysics,63rd Ed.,CRC,Boca Raton,FL,1982,p.F-36.[13]D.J.Stein,A.Maskara,S.Haereid,J.M.Anderson,D.M.Smith,in:A.K.Cheetham,C.J.Brinker,M.L.Mecartney,C.Sanchez(Eds.),Better Ceramics Through ChemistryVI,Materials Research Society,Warrendale,PA,1994, p.643.nd et al./Journal of Non-Crystalline Solids283(2001)11±1717。
