【作者】 房家妹；

【导师】 郭清萍； 邵双喜；

【作者基本信息】 太原理工大学 ， 材料学， 2011， 硕士

【摘要】 聚乙烯(PE)具有比重小、易加工成型、绝缘电阻高、介电性能优良等优点。聚乙烯分子无极性、分子间的范德华力较弱,造成聚乙烯与无机物以及极性高分子相容性差、抗热变形能力差、机械强度不高等缺点,限制了聚乙烯的使用。硅烷交联改性是解决这些问题的有效途径之一硅烷交联改性可以提高聚乙烯的冲击强度、耐热性能、耐环境应力开裂性能。传统的温水硅烷交联存在交联速度慢、交联不均匀的缺点。本文选用硬脂酸和氧化锌作为产水剂,使硅烷接枝低密度聚乙烯(LDPE)在室温下发生自交联反应。得出以下结论：(1)硅烷是交联反应的主要原料之一,选用乙烯基三乙氧基硅烷(A-151)、新型硅烷(HIT-176)、乙烯基三甲氧基硅烷(A-171)、乙烯基-三(2-甲氧基乙氧基)硅烷(ZQ-172)作为硅烷接枝单体,制备的接枝聚乙烯的吸光比R分别为0.424、0.906、0.777、0.730。以硅烷A-151,硅烷HIT-176作为接枝单体制备交联聚乙烯,凝胶含量均超过65%(温度为90℃热水中交联40h)。(2)以叔丁基过氧化3,5,5一三甲基己酸酯(TBPMA)为引发剂,接枝料的吸光比R随TBPMA含量的增加而增加,当TBPMA的含量为0.15pbw时,自交联聚乙烯六天后凝胶含量达到70%；选择硬脂酸、氧化锌为产水剂,在催化料中含量分别为1.0pbw、3.5pbw时,自交联聚乙烯的凝胶含量达到46.7%,样品的拉伸强度提高；催化剂含量在1.5pbw～3.0pbw之间,对自交联样品的综合性能的影响不明显；选用硅烷A-151、硅烷HIT-176作为接枝单体,经过6天的自交联反应,DLPE的凝胶含量分别为45%、71%,其中硅烷HIT-176的含量是2.5pbw。(3)应用傅里叶变换红外光谱(FTIR)和差示扫描量热法(DSC)研究了聚乙烯硅烷接枝和室温自交联反应。硅烷接枝及自交联反应对LDPE结晶行为有明显的影响：接枝和交联后,LDPE的Avrami指数n在3.8-6.0之间,高于纯LDPE的Avrami指数2.52；Avrami指数随引发剂含量的增加先增加后降低,随催化剂含量的增加而降低；硅烷接枝聚乙烯的结晶动力学速率常数高于纯LDPE的结晶动力学速率常数,而自交联LDPE的结晶动力学速率常数低于纯LDPE的结晶动力学速率常数。更多还原

【Abstract】 With a low specific weight and easy processing characteristics, polyethylene also has the advantage of high insulation resistance, excellent dielectric properties. Since polyethylene has a weak van der Waals forces between molecules, non-polar chain, so it has a poor compatibility with inorganic matters and polar polymers, poor heat change properties, and its mechanical strength is not high, which limits its applications. Grafting and crosslinking may be the feasible ways to adjust these disadvantages.The application of silane crosslinking can improve the performance of polyethylene, such as impact strength, heat resistance and segregation resistance. The polyethylene grafted or crosslinked by silane has disadvantages such as low speed and lack of homogeneity in crosslinking through traditional manners using hot water. In this thesis, self-crosslinked PE at room temperature was prepared through a two-step method by means of stearic acid and zinc oxide to release water. Followings are the main accomplishments:(1) Silane is one of the key factors in self-crosslinking. The absorbance ratio of LDPE-g-silane with silane A-151, silane HIT-176, silane A-171 and silane ZQ-172 is 0.424,0.906,0.777 and 0.730, respectively. And the gelation of crosslinked LDPE grafted by silane, which used silane A-151 and silane HIT-176, could surpass 65% after being crosslinked in hot water for 40 hours (at 90 degrees centigrade).(2) Silane could be grafted onto PE through TBPMA. The absorbance ratio of self-crosslinked LDPE increased with the content of TBPMA. The gel of self-crosslinked LDPE could surpass 71%. The best content of TBPMA is 0.15pbw; when the content of stearic acid and zinc oxide was 3.5pbw and 1.Opbw, respectively, the self-crosslinked LDPE could have the most amount of gel about 46.7%; Catalyst has litter influence on the performance of self-crosslinked LDPE when the content is 1.5pbw～3.0pbw; The gel of self-crosslinked LDPE which used silane A-151 and silane HIT-176 were 45%, 71%, respectively. The best content of silane HIT-176 is 2.5pbw.(3) Both grafted and crosslinked LDPE were studied using FTIR and differential scanning calorimeter (DSC). As a result, the reactions of silane grafting and self-crosslinking have excellent impacts on the change in crystallization behavior,the values of Avrami index(n) of LDPE was 2.52, while increased to 3.8～6.0 when the LDPE was grafted or cross-linked. The values of Avrami index increased to the maximum and then decreased with increasing loading of initiator, while decreased with increasing loading of catalyst. Compared with neat LDPE, the velocity constant of the crystallization of silane grafted LDPE became higher, while that of crosslinked LDPE became smaller.更多还原