【作者】 牟海艳；

【导师】 郭卫红；

【作者基本信息】 华东理工大学 ， 材料科学与工程， 2012， 博士

【摘要】 橡胶及热固性树脂等交联聚合物的材料回收方法,尤其是化学回收方法的开发是聚合物材料科学研究中特别值得关注的重大难题之一。由于聚合物交联的网络结构给发展合适的回收方法带来了困难,因此人们一直在寻求新的解决方案。可逆的交联-解交联结构是解决高效回收利用问题的科学方案。配位键是最强的非共价键,又具有可逆性。本文将配位键引入到橡胶交联网络的构筑,开发橡胶硫化技术,制备新型可逆交联的橡胶/金属盐复合材料。借助红外光谱、电子顺磁共振表征金属离子与高分子配体问形成的配位键。利用DSC、DMA、平衡溶胀法等手段分析配位交联网络的形成过程。采用SEM分析金属盐在橡胶基体中的分散状态和橡胶-金属盐界面相互作用。有机聚合物与金属盐填料共混时,相容性是影响材料最终性能的重要因素。本研究针对制备丁腈橡胶橡胶(NBR)/金属盐复合材料遇到的这一问题,实施了三个方案：1)利用氨络合硫酸铜在受热时,铜离子上络合的氨释放,暴露出反应活性点与丁腈橡胶的腈基发生原位配位反应,制备了具有良好界面相互作用力的NBR/Cu(NH3)4SO4·H2O复合材料；2)利用有机金属盐与丁腈橡胶良好的相容性,将硬脂酸锌、铜、铁、锰分别与丁腈橡胶共混,制备了颗粒尺度小、分散性良好的丁腈橡胶／过渡金属硬脂酸盐配位交联复合材料；3)利用氯化锌易吸水潮解的性质,并且水分的存在有利于配位反应的发生,获得了ZnCl2添加量<10 phr时,均相的NBR/ZnCl2配位交联复合材料。丙烯酸酯橡胶(AR)是一类饱和橡胶,它的酯基可以作为配体,将配位硫化的方法推广到AR的交联具有重要意义。在AR/CuSO4复合材料中,酯基中的两个氧原子均参与与铜离子的配位,形成了交联网络。AR与CuSO4的配位反应在室温即可进行。180℃形成配位交联网络的速度最快,CuSO4颗粒表面形成一个厚度达500 nm的界面层。AR/NBR/CuSO4复合材料内同时形成了-COOR→Cu2+和-CN→Cu2+配位键,利用硫酸铜作为交联剂实现了对AR/NBR合金配位共硫化。随着AR/NBR合金含量接近时,AR/NBR/CuSO4复合材料体系中配位交联反应越难发生,配位交联网络越不易形成,CuSO4粒子在基体中的尺寸和形状也发生改变。AR/NBR/CuSO4(10/90/10)复合材料具有最优的力学性能(932.23%,43.73MPa)和热稳定性(411℃分解,700℃下残余质量22.63%)。对丁腈橡胶的配位交联网络的可逆性进行了研究。NBR/CuSO4和NBR/ZnCl2的配位交联网络均可溶解在DMF 95℃溶剂中。实现了丁腈橡胶配位交联复合材料交联-解交联-交联的可逆过程。更多还原

【Abstract】 The development of methodologies for material recycling, especially chemical recycling of crosslinked polymers, such as thermosetting resins and rubbers, is one of the most important issues in polymer and material science. Because of the difficulty in developing suitable recycling methodologies owing to the network structure of polymers, a new recycling concept has long been sought after. Reversible crosslinking-decrosslinking may constitute an efficacious recycling protocol.Coordination bond is the strongest non-covalent bond and reversible. In this study coordination bond was employed to build rubber network structures; vulcanization technology based on coordination-bonded crosslink was developed;novel reversible crosslinked rubber/metallic salt composites were prepared.Infrared spectra (FT-IR) and electron spin resonance (ESR) were applied to characterize the coordination bonds formed between metal ions and polymeric ligends.The formation of coordination-bonded networks was analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and a swell equilibrium method.The morphology of metallic salt particles dispersed in polymer matrix and the interface between polymer and particles were observed by scanning electron microscope (SEM).Compatibility is one of the most important factors affecting the performance of polymer-metal salt composites. On this issue efforts were made in three aspects:first, NBR/ Cu(NH3)4SO4·H2O composites with strong interface interactions were prepared, in that Cu(NH3)4SO4·H2O was active to form coordination bond with nitrile groups when ammonia released on heating; second, owing to the good compatibility between organic polymer and transitional metallic streates, well-dispersed coordination-crosslinked NBR/zinc streate, NBR/copper streate, NBR/ferric streate and NBR/ manganese streate composites were obtained;third, a homogeneous NBR/ZnCl2 composite were prepared when the content of ZnCl2 was no more than 10 phr, as a result of great deliquescence of ZnCl2.Acrylic rubber (AR) is a saturated rubber with ester carbonyl groups as potential ligends. It is of significance to vulcanize AR via coordination bonds.Both of the two oxygen atoms of ester carbonyl group coordinated with copper ion in AR/CuSO4 composites. The coordination reaction between AR and CuSO4 can carry out at room temperature.The coordination bonded networks formed fast at 180℃, and CuSO4 particles were encapsulated by a 500 nm thick interface layer.Copper sulfate was incorporated into AR/NBR alloy to co-vulcanize the two components through simultaneous formation of -COOR→Cu2+ and -CN→Cu2+ coordination bonds. The nearer the ratio of AR/NBR approached 1, the harder the coordination reactions took place and the looser crosslinking networks formed in AR/NBR/CuSO4 compounds. Moreover, shapes and sizes of copper sulfate particles changed with the ratio of AR/NBR. AR/NBR/CuSO4(10/90/10) composite had the optimum mechanical properties (932.23%, 43.73MPa) and good thermal stability (decompose temperature 411℃,22.63% residue at 700℃).Finally, the reversibility of networks of coordination-bonded NBR-based composites was investigated in this study. The coordination-bonded cross linking networks of NBR/CuSO4 and NBR/ZnCl2 composites could dissolve in DMF at 95℃. A reversible crosslinking-decrosslinking- crosslinking was achieved in NBR/ZnCl2 composites.更多还原