【作者】 王芳；

【导师】 和克智； 任鹏刚；

【作者基本信息】 西安理工大学 ， 食品科学， 2009， 硕士

【摘要】 淀粉为多羟基的刚性天然高分子材料,脆性及较差的强度是阻碍该类材料应用的关键,因此提高塑料的塑性及力学性能已成为淀粉塑料的主要发展方向。蒙脱土是一种天然的层状硅酸盐,来源广且价格低廉,其片层结构厚度及层间距均处于纳米尺度,能够有效地改善淀粉塑料的力学性能。淀粉/蒙脱土是工业化应用前景非常好的一种聚合物基纳米复合材料。为此本文采用有机处理剂十二烷基-二甲基-基溴化铵作为插层剂与蒙脱土进行离子交换反应,制备了有机蒙脱土OMMT。通过尿素和乙醇胺复合增塑剂对红薯淀粉进行了塑化,利用熔融共混挤出的方法制备了蒙脱土/淀粉纳米复合材料,实现了TPS与蒙脱土在纳米尺度上的复合。主要结论如下：首先采用长链季铵盐阳离子表面活性剂十二烷基-二甲基-苄基溴化铵对钠基蒙脱土进行有机化处理,制得有机蒙脱土。采用红外(FT-IR)、X射线衍射(XRD)、热重分析(TGA)等手段对有机蒙脱土的结构进行了表征,结果表明长链季铵盐表面活性剂与蒙脱土进行了离子交换反应,改性前后蒙脱土的层间距从1.50nm扩张到1.70nm,层间距有一定程度的扩张,插层效果显著。MMT与OMMT的热重分析表明有机改性的蒙脱土热稳定性较改性前有所提高。MMT与OMMT的表面性能研究表明：天然蒙脱土的亲水性极佳,而经过改性后的蒙脱土由原来的亲水性变为亲油性,从而有利于其与聚合物的结合。用扫描电镜对原淀粉、热塑性淀粉及复合材料的微观形貌进行了研究。经过尿素和乙醇胺塑化剂塑化后,原来的淀粉颗粒受到一定程度的破坏,形成均一的连续相。从蒙脱土含量为4%的淀粉/蒙脱土纳米复合材料的SEM形貌图中可以看出,蒙脱土均匀的分散在热塑性淀粉基制中,形成稳定的淀粉/蒙脱土纳米复合材料。XRD测试结果表明：未加入蒙脱土的塑化淀粉(TPS)有着一小部分结晶峰。而添加OMMT后,复合材料则没有明显的结晶峰出现,这说明蒙脱土的晶格结构已被破坏,MMT被均匀地分散在聚合物中。力学性能测出：随着蒙脱土含量的增加TPS的拉伸强度和拉伸模量均有较大程度的材料的断裂伸长率明显下降,由原来的90%分别下降到80%、75%、60%和50%。添加了蒙脱土的纳米复合材料与纯的热塑性淀粉相比其耐水性能有了很大的提高。更多还原

【Abstract】 As the rigidity of natural polyhydroxy polymer materials, its brittleness and the bad intensity are the key question hindering this kind of material application, therefore the plasticity and mechanics performance of plastic has become the main development of the starch plastic. The montmorillonite is one kind of natural layered silicate, it originates broadly and its price is also inexpensive, its laminar structure is thickness and the level spacing is in a nanometer criterion, it can effectively improve the starch plastic mechanics performance. The starch/montmorillonite is one kind of polymer based nanometer compound materials, it has extremely good industrialization application. So this paper uses the organic finishing agent lauryl-dimethyl-phenmethyl ammonium bromide as the intercalation agent carries on the ionic exchange response with the montmorillonite clay, has prepared organic montmorillonite clay OMMT. Through urea and ethanolamine compound plasticizers for plasticizing sweet potato starch, altogether using extrusion melt blending method to prepare montmorillonite clay/starch nanometer compound materials, has realized TPS and montmorillonite clay in nanometer criterion bonding. The main conclusion is as follows:Firstly, uses the long chain quaternary ammonium salt positive ion surface active agent lauryl-dimethyl-phenmethyl ammonium bromide to carry on organizing processing to the sodium base montmorillonite clay, makes the organic montmorillonite clay. Uses infrared (FT-IR), X-ray diffraction(XRD), thermo gravimetric analysis (TGA) and other methods to characterize the organic structures of montmorillonite, finally it indicates that the long chain quaternary ammonium salt surface active agent all carry on the ionic exchange response with the montmorillonite clay, around the modification the montmorillonite clay level spacing expanded from 1.50nm to 1.70nm, the level spacing has certain degree expansion, with significant effect of intercalation.MMT and the OMMT thermo gravimetric analysis indicate the organic modified montmorillonite clay thermo stability has an enhancement compares before modification. MMT and the OMMT superficial performance research indicate that, the natural montmorillonite clay water affinity is extremely good, but after modified, the montmorillonite clay becomes lipophilic, thus it is advantageous to union with the polymer.Using scanning electron microscopy of the original starch, thermoplastic starch and composite materials to study their morphology. After plasticizing of the urea and the ethanolamine elasticizer, the original starch pellet receives certain degree of the destruction, forms the homogeneous continuous phase. Separately from the montmorillonite content of 4% and 8%, the starch/montmorillonite nanocomposites SEM morphology diagram can be seen that the montmorillonite clay even disperser in the thermoplastic starch base, forms stable starch/montmorillonite clay nanometer compound materials.The XRD test indicates that, plastified starch (TPS) which doesn’t join the montmorillonite clay has a small part of crystallization peak. But after adding OMMT, the compound materials do not have the obvious crystallization peak appearance, this explains the montmorillonite clay lattice structure is destroyed; MMT is dispersed evenly in the polymer.Mechanics performance determines:along with the montmorillonite clay content increasing, the TPS longitudinal strength and the stretch modulus have a great degree enhancement, enhances from original 4.2MPa to 5.2 MPa,6 MPa,6.2 MPa and 6.8Mpa; But the montmorillonite clay joins causes the break elongation ratio of material drops obviously, from original 90% drops separately to 80%,75%,60% and 50%.After adding montmorillonite the nanocomposites has a greatly improve in water resistance compares to pure thermoplastic starch.更多还原