探究四种增塑剂对淀粉粘合剂韧性的影响(三等奖)

0作品类别：A类（自然科学类学术论文及实验）作者：郝舒萌陈贝金瑛灿石明飞指导老师：张军营实验由参赛者2011年上半年在东区实验室完成北京化工大学材料科学与工程学院探究四种增塑剂对淀粉粘合剂韧性的影响1目录1引言·····················································································································22实验原理···············································································································32.1淀粉的糊化········································································································32.2增韧················································································································53实验器材及原料·······································································································64实验方法及过程·······································································································74.1氧化玉米淀粉的糊化····························································································74.220%聚乙烯醇溶液的制备·······················································································94.3四种增塑剂对淀粉粘合剂韧性的影响·······································································94.4氯化钙与聚乙烯醇混合后不同比例对淀粉粘合剂粘度的影响········································114.5氯化钙、聚乙烯醇与淀粉粘合剂相容性探究····························································124.615%氯化钙与聚乙烯醇共混后对淀粉粘合剂韧性的影响··············································125实验结果·············································································································125.1四种增塑剂对淀粉粘合剂韧性的影响·····································································125.2氯化钙与聚乙烯醇混合后不同比例对淀粉粘合剂粘度的影响·······································145.3氯化钙、聚乙烯醇与淀粉粘合剂相容性探究····························································155.415%氯化钙与聚乙烯醇共混后对淀粉粘合剂韧性的影响··············································166结论···················································································································177结语···················································································································172摘要：目的：优选四种增塑剂最优效果配比。方法：采用正交分析法进行探究，以表征、粘力及离心效果等为考察指标对结果进行分析。结果：综合考虑市场因素及实验结果，本实验所得最优增塑方案为15%氯化钙+2.5%聚乙烯醇。结论：按最优配比添加的增塑剂可对淀粉粘合剂起到最优增韧的效果。关键词：巴布剂;淀粉粘合剂;增塑性;相容性1引言巴布剂指中药提取物或药物,与适宜的亲水性基质和适量比例的辅料混匀后涂于布上制成的外用制剂,作为新型外用透皮贴剂,已在国外大量应用。巴布剂于20世纪70年代率先由日本生产出,80年代初引入中国,90年代我国开始规模生产[1][2]。由于具有载药量大,透气性、贴敷性、保湿性好、刺激性小、应用方便等舒适优点,巴布剂在多种疼痛性疾病的临床治疗中深受患者欢迎[3]。但目前，使用在巴布剂基质中的粘合剂主要是石油化工类产品，如：甲基乙烯基醚和顺丁烯二酸酐的共聚物、聚丙烯酸盐类等，有些价格偏昂贵，且不利于环境的可持续发展。淀粉粘合剂具有无毒、无污染、强度较高、无腐蚀、不污染环境、原料来源广、成本低、制备工艺简单等优点，在近几年倍受青睐，用天然淀粉制作各种粘合剂已成为国内外的发展趋势。如能将淀粉粘合剂作为巴布剂的粘着剂将会为巴布剂带来新的发展契机。然而，淀粉粘合剂也有制约其广泛应用的因素，其中韧性差大大阻碍了它发展的脚步。本实验即是通过正交分析法探究四种增塑剂对过氧化氢氧化玉米淀粉粘合剂韧性的影响，以此判断出了增韧的最优试剂与最优配比。32实验原理2.1淀粉的糊化淀粉是右旋葡萄糖聚合物,通式是(C6H10O5)n。淀粉有直链淀粉和支链淀粉两类，直链淀粉由α-1,4葡萄糖苷键连接而成，在淀粉中约占23%。支链淀粉是由右旋葡萄糖生成的分支巨大分子，其中含一种磷酸酯，可生成一种糊，其主链以α-1,4糖苷键方式连接，支链以α-1,6糖苷键连接。其在淀粉中约占77%。淀粉之所以能成为一种良好的粘合剂，就是因为具备了可生成糊的支链淀粉，而另一部分直链淀粉又能促进其发生胶凝作用。[4]图1淀粉分子结构图2淀粉颗粒结构图3原淀粉的SEM（×1000，×5000）图4原淀粉的SEM（×1000，×5000）淀粉颗粒不溶于水，但在水中能吸收少量水分，颗粒稍膨胀。普通玉米淀粉和马铃薯淀粉在水中所含平衡水分大约28％和33％。这种吸水和膨胀现象是可逆的，水分被4干燥后仍恢复原来的颗粒结构大小[5]。混淀粉于水中，不停地搅拌。颗粒悬浮于水中，形成白色悬浮液，称为淀粉乳。加热淀粉乳，颗粒随温度的升高，吸水更多，膨胀更大，达到一定的温度，原淀粉结构被破坏，吸水膨胀成粘稠胶体糊。这种现象称为糊化，其温度称为糊化温度，形成的胶体称为淀粉糊。图5膨胀淀粉颗粒的胶束结构淀粉的糊化温度在不同品种间存在差别，同一种淀粉在大小不同的颗粒间也存在差别。大颗粒易糊化，糊化温度低，小颗粒难糊化，糊化温度高。010002000300040000200400600800100012001400ViscosityTime/sViscosity/cPABCt1t230405060708090100TemperatureTemperature/℃图6木薯原淀粉的粘度-温度-时间曲线52.2增韧高分子材料的增韧，是由于材料中高聚物分子链间聚集作用的削弱而造成的。增塑剂分子插入到聚合物分子链间，削弱了聚合物分子链间的引力，结果增加了聚合物分子链的移动性，降低了聚合物分子链的结晶度，从而使聚合物的韧性增加。ⅰ增塑剂的分类：①按分子量大小分：单体型和聚合型。②按性能分：通用型、无毒增塑剂等。③按结构分：邻苯二甲酸酯、脂肪族二元酸酯、磷酸酯、环氧化合物、聚酯、脂肪酸酯、多元醇酯、含氯增塑剂、柠檬酸酯、苯多酸酯、烷基磺酸酯、石油酯等类ⅱ增塑剂的主要作用:削弱聚合物分子间的范德华力，增加聚合物分子链的移动性，降低聚合物分子链的结晶性。ⅲ增塑剂分为内增塑剂和外增塑剂。①内增塑剂：在聚合物的聚合过程中引入第二单体，由于第二单体共聚在聚合物的分子结构中，故降低了聚合物分子链的结晶度。内增塑的另一类型是在聚合物分子链上引入支链(或取代基或接枝的分支)。由于第二单体与聚合物链段具有稳定的化合结合，所以不被介质所抽出，但从工艺和成本上考虑，内增塑剂的使用温度范围比较窄。②外增塑剂：一般为外加到聚合体系中的高沸点的较难挥发的液体或低熔点固体物质。6531.23577.04710.23765.18862.21931.10996.101082.271158.841378.641601.842168.272362.892928.933400.585658606264666870727476788082848688909294%T1000200030004000Wavenumbers(cm-1)图7氧化淀粉的红外谱图空间有规结构的聚合物的分子链适当的条件下能够结晶，即链状分子从卷的和杂乱的状态变成紧密折叠成行的有规则状态。在一般条件下，工业生产的聚合物不可能是完全结晶的，而往往是由结晶区域散插在无定形区域构成的。显然，增塑剂的分子插入结晶区域要比插入无定形区域困难得多，因为在结晶区与聚合物与链之间的自由空间最小。如果增塑剂的分子仅能插入部分结晶的聚合物的无定形区域，则此增塑剂便是非溶剂型增塑剂，也就是所谓的辅助增塑剂。如果增塑剂的分子仅能插入聚合物的无定形区域同时又能插入结晶区域，则此增塑剂便是溶剂型增塑剂，即所谓的主增塑剂。3实验器材及原料器材：烧杯、粘度仪、鼓风烘箱、加热台、磁力搅拌机、油浴锅、三口烧瓶、温度计、电子天平、离心机、离心管、玻璃棒、透明塑料杯、聚酯薄膜、隔离纸、塑料胶头滴管原料：见表17表1实验所需原料及作用和用量范围实4验方法及过程注：①以下百分比除特殊说明外均为占氧化玉米的量②所有实验用品、用量均是以文献及其上已完成的实验的结果为基础进行筛选后所定4.1氧化玉米淀粉的糊化用电子天平准确称量105.00g的氧化玉米淀粉溶于195g去离子水中，加入磁子，塞好橡胶塞，并在侧孔处插入量程为100摄氏度的温度计。将三口烧瓶放入油于锅中，控制瓶内温度在90℃-100℃加热搅拌四十分钟左右，并每隔5分钟进行一次粘度测定，直到氧化淀粉成黄色半透明状且粘度适宜为止，瓶内即为所需氧化玉米淀粉粘合剂。实验思考：起初我们用加热台通过直接加热法来糊化淀粉，但由于对糊化淀粉的透明状态把握原料氧化玉米淀粉三醋酸甘油酯氯化钙丙三醇聚乙烯醇(0588)去离子水作用制备淀粉粘合剂增塑剂增塑剂增塑剂增塑剂溶剂用量范围35%（占总淀粉粘合剂的百分比）5%-20%5%-20%5%-20%2%-5%略8不是很准确，导致糊化一直不到位，且在实验中存在其他影响因素，如加热台温度无法控制，糊化点难以把握等。通过上述实验的失败我们最终决定用三口烧瓶做容器，油浴锅做加热装置。用此法可糊化较多氧化淀粉溶液，解决了实验对糊化淀粉溶液的需求，且可较好把握糊化点，把握加热时间和糊化程度。图8油浴、搅拌图9测定粘度94.220%聚乙烯醇溶液的制备用电子天平准确称量0588聚乙烯醇粉末20.00g于烧杯中，加入80g约50-60℃的去离子水，边加边用玻璃棒搅拌，直至聚乙烯醇粉末完全溶解，溶液呈透明粘稠状为止。所得溶液即为20