POLYMER NANOCOMPOSITES REINFORCED BY CELLULOSE WHISKERS
POLYMER NANOCOMPOSITES REINFORCED BY CELLULOSE WHISKERS
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DOI：
10.1021/ma00122a053
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发表时间：
1995-08-28
期刊：
影响因子：
5.5
通讯作者：
CAVAILLE, JY
中科院分区：
文献类型：
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作者：
FAVIER, V;CHANZY, H;CAVAILLE, JY
有许多例子，其中动物或植物合成细胞外的高性能生物复合材料，其由纤维生物聚合物增强的基质组成。1-3纤维素是这些增强元素的经典实例，其作为生物合成并以连续方式沉积的须状微纤维出现。4-5在许多情况下，这种模式的生物成因导致结晶微纤维，几乎是无缺陷的，与轴向的物理性质接近完美的晶体的结果。在本研究中，我们试图通过将被囊动物外套的纤维素须与合成聚合物乳液混合来模拟生物复合材料。从这样的混合物浇铸的膜具有纳米复合材料的组织，其结构和机械性能在本文件中描述。一批来自地中海的食用级被囊Microcosmus fulca-tus从当地的鱼店获得。这些海洋动物的总直径在5到10厘米之间，具有1厘米厚的纤维素外套。用氯仿麻醉后，动物被开膛破肚，它们的外套被切成小碎片，按照Wise等人的方法，通过三次连续的漂白处理来去除蛋白质。（“衣素”）然后在水中分解，先是用华林搅拌机（浓度为5重量%），然后通过在400巴下操作的Gaulin实验室均化器15次（浓度为1重量%）。将所得的被衣素水性悬浮液与H2SO 4混合以达到55%重量分数的最终酸/水浓度。水解条件是在强烈搅拌下在60 ℃下水解20分钟。得到纤维素晶须的分散体。超声处理后，将悬浮液中和并通过透析洗涤。它没有沉淀或絮凝的结果，在硫酸处理过程中产生的表面硫酸盐基团。当通过蒸发浓缩时，悬浮液显示出典型的液晶特性。8将纤维素晶须的悬浮液与由苯乙烯（35%w/w）、丙烯酸丁酯（65%w/w）和少量丙烯酸共聚得到的聚合物胶乳（Tg= 0 ℃）均匀混合。将悬浮液倒入聚（亚乙基）模具中，并使其在室温下缓慢干燥1个月。得到均匀且无气泡的2 mm厚的膜。将这些膜切成35 mm长和6 mm宽的条，用DMTA Metravib SA Mecanalyseur分析，该分析仪与强制振荡摆一起操作。实验在0.1Hz的固定频率和200-500 K的温度范围内进行。
There are numerous examples where animals or plants synthesize extracellular high-performance skel-etal biocomposites consisting of a matrix reinforced by fibrous biopolymers. 1-3 Cellulose is a classical example of these reinforcing elements which occur as whiskerlike microfibrils that are biosynthesized and deposited in a continuous fashion. 4-5 In many cases, this mode of biogenesis leads to crystalline microfibrils that are almost defect-free, with the consequence of axial physical properties approaching those of perfect crystals. In the present study, we have attempted to mimic biocomposites by blending cellulosewhiskers from the mantles of tunicates with synthetic polymer latices. The films cast from such mixtures had a nanocomposite organization whose structure and mechanical properties are described in the present paper. A batch of edible-grade tunicate Microcosmus fulca-tus, from the Mediterranean, was obtained from a local fish shop. These sea animals had an overall diameter between 5 and 10 cm with a 1 cm thick cellulose tunic.After anesthetizing with chloroform, the animals were gutted and their tunic was cut into small fragments that were deproteinized by three successive bleaching treatments, following the method of Wise et al. 6 The bleached mantles (the “tunicin”) were then disintegrated in water, first with a Waring blender (at a concentration of 5% by weight) and then with 15 passes through a Gaulin laboratory homogenizer operatedat 400 bar (at a concentration of 1% by weight). The resulting aqueous tunicin suspension was mixed with H2SO4 to reach a final acid/water concentration of 55% weight fraction. Hydrolysis conditions were 60 C for 20 min under strong stirring. A dispersion of cellulose whiskers resulted. After sonication, the suspension was neutral-ized and washed by dialysis. It did not sediment or flocculate as a consequence of surface sulfate groups created during the sulfuric acid treatment. 7 When concentrated by evaporation, the suspensions displayed typical liquid crystal characteristics. 8 The suspensions of cellulose whiskers were homoge-neously mixed with polymerlatices {Tg= 0 C) resulting from the copolymerization of styrene (35% w/w), butyl acrylate (65% w/w), and a small amount of acrylic acid. The suspensions were poured into poly (tetrafluoroeth-ylene) molds and allowed to dry slowly for 1 month at room temperature. Homogeneous and bubble-free 2 mm thick films resulted. These films, cut into strips 35 mm long and 6 mm wide, were analyzed with a DMTA Metravib SA Mecanalyseur operatingwith a forced oscillation pendulum. The experiments were achieved at a fixed frequency of 0.1 Hz and in a temperature range 200—500 K.