乙烯基不饱和硅烷交联改性PP制备HMSPP

采用乙烯基不饱和硅烷接枝交联复合改性聚丙烯(PP)制备高熔体强度聚丙烯(HMSPP)。由正交试验可知,过氧化二苯甲酰对乙烯基长链不饱和硅烷交联改性PP制备的HMSPP熔体强度的影响最显著。通过优化实验得到的HMSPP熔体强度为19.9cN。二乙烯基苯(DVB)作为助交联剂可有效提高HMSPP的熔体强度,w(DVB)不宜超过1.0%。苯乙烯质量分数为1.0%时,对HMSPP链断裂抑制较明显。采用复合改性PP制备的HMSPP的断裂拉伸应变略有下降,熔体强度相比PP提高4.7倍,悬臂梁缺口冲击强度提高0.82倍。     

丙酮溶剂法挤出交联改性聚丙烯制备HMSPP

对聚丙烯T30s接枝交联复合改性制备高熔体强度聚丙烯(HMSPP)进行了研究,分别由正交实验和曲面响应分析可知,BPO对乙烯基长链不饱和硅烷交联改性T30s粒料和粉体制备HMSPP熔体强度的影响最显著;在粒料反应中通过优化实验,得到的HMSPP熔体强度为19.9 c N;在粉体反应中,通过优化实验,得到的HMSPP熔体强度为21.1 c N。二乙烯基苯(DVB)作为助交联剂可有效提高HMSPP的熔体强度,St对PP链断裂抑制较明显。交联改性中聚丙烯WB130的加入可使改性制得的HMSPP熔体强度显著提高,当WB130加入量为40%时,熔体强度可达34 c N。     

聚丙烯发泡材料的应用及研究进展

综述了聚丙烯（PP）发泡材料的应用及其发展的优越性,分析了目前PP发泡材料制备过程中存在的问题,指出了改善PP发泡性能的关键是制备高熔体强度聚丙烯（HMSPP）,介绍了国内外HMSPP的制备及其发泡的研究进展,指出硅烷接枝交联改性技术具有成本适中。产品质量好并容易控制的特点,是目前的HMSPP制备技术中最有希望的技术。     

高熔体强度聚丙烯的发泡性能研究

通过反应挤出法对聚丙烯(PP)进行硅烷接枝交联改性获得高熔体强度PP(HMSPP),并对HMSPP的发泡性能及影响因素进行了研究。结果表明,HMSPP具有良好的发泡性能,可以制备出高质量泡沫材料;随着HMSPP的熔体流动速率的降低,泡沫材料的密度和泡孔平均直径降低;随着HMSPP用量减少,HMSPP/PP泡沫材料的泡孔平均直径和密度增大,泡孔尺寸及分布的不均匀程度增加;发泡条件对泡沫结构具有一定的影响,最佳的发泡温度为185~190℃,螺杆转速为40~100r/min;随着口模厚度的增加,泡孔平均直径增加,材料密度下降,而材料内外层泡孔直径不均匀性增加。     

聚丙烯化学改性方法

综述了聚丙烯的化学改性方法,包括接枝、交联、共聚等,接枝主要包括熔融接枝、溶液接枝、悬浮接枝、辐射接枝、超临界CO2协助接枝、固相接枝及非极性单体在PP上的接枝,交联改性主要包括有机氧化物交联、氮化物交联、辐射交联及等离子体交联,最后简要介绍了共聚改性以及PP改性的最新进展.     

PVC接枝改性及交联改性方法研究进展

综述了近年来聚氯乙烯（PVC）接枝改性和交联改性方法的研究进展;其中,接枝改性方法包括在PVC链的C原子上接枝含C、N、S元素基团等及其他亲核取代方法;交联改性方法包括过氧化物交联、三嗪化合物交联、双烯化合物交联、硅烷交联及其他化学交联方法等;最后,对PVC化学改性的发展前景进行了展望。     

国内聚乙烯接枝和交联改性的研究进展

综述了国内聚乙烯接枝改性和交联改性技术的最新进展。     

马来酸酐辐照接枝三元乙丙橡胶的研究

采用辐照技术,用马来酸酐(MAH)对三元乙丙橡胶(EPDM)进行接枝改性,测定接枝物的交联度和接枝率.分析了辐照剂量、马来酸酐用量以及阻交联剂用量对接枝物交联度和接枝率的影响.同时,采用正交试验优化了试验参数.结果表明,当辐照强度为0.3 kGy/h、辐照剂量为0.15 kGy、MAH与EPDM的质量比为0.025:1以及阻交联剂的质量分数为0.02%时,接枝率达到1.35%.     

改性淀粉胶粘剂研究进展

介绍了淀粉的改性机制和3种改性方法(物理改性、化学改性和生物改性),特别综述了化学改性法中氧化、酯化、醚化、接枝、交联和复合改性(包括酯化交联、接枝共聚、氧化交联、醚化交联和醚化酯化等)等方法的研究进展。最后对淀粉胶粘剂的改性方向进行了展望。     

改性大豆蛋白胶粘剂的研究进展

综述了碱降解改性大豆蛋白胶粘剂的研究进展以及接枝共聚反应在交联改性反应中的重要性,认为在复合碱降解改性大豆蛋白基础上进行接枝共聚改性作为一种与交联反应方法平行的改进方法或补充方法是可行的。     

Thermal and crystallization behavior of silane‐crosslinked polypropylene

Silane‐crosslinked polypropylene (PP) has been prepared first by the grafting of silane onto the backbone of PP in a melt process and then by crosslinking in warm water. The effects of type and concentration of silane and peroxide on the silane grafting on PP were investigated. The thermal behavior of the silane‐crosslinked PP was studied by thermogravimetric (TG) and differential scanning calorimetry (DSC) methods. TG results show that PP prepared via silane crosslinking increases its thermal stability greatly. It has been found from DSC measurements that the crystallization temperatures, ie the onset temperature and peak temperature of the exotherm of the silane‐crosslinked PP, increase compared with those of the pure PP. The silane crosslinking hardly changes the crystallinity degree of PP. The crystallization behavior of the silane‐crosslinked PP was also studied by wide‐angle X‐ray diffraction analysis. Copyright © 2004 Society of Chemical Industry     

二甲基二苯基丁烷的应用

利用二甲基二苯基丁烷（DMDPB）作为阻燃增效协同剂与十溴联苯醚在聚丙烯上作了阻燃试验,聚丙烯的防火级别可达FV－0;利用DMDPB作为接枝催化剂,在聚丙烯上作了接枝马来酸酐的试验,马来酸酐的含量达到2．37％;利用DMDPB作为交联引发剂,用聚乙烯进行了紫外交联试验,交联度达到36．9％。     

Nondegradative melt functionalization of polypropylene with glycidyl methacrylate

The melt grafting of glycidyl methacrylate (GMA) onto powdered isotactic polypropylene (PP) in a Haake Rheocord RC90 mixer was studied. Grafting degrees were determined by nonaqueous back titration of trichloroacetic acid with sodium hydroxide. The extent of degradation and crosslinking of PP during grafting was indicated by the melt-flow rates (MFR) of the grafted samples. The influences of GMA concentration, initiator type and concentration on grafting degree, reaction efficiency, and degradation were evaluated. A novel method was developed to obtain a high grafting degree with little degradation of PP using acrylamide (AM) as the initiating agent. The grafting process occurred before or during the melting of PP (i.e., solid-state grafting), at which temperature crosslinking is preferred over chain scission. Primary free radicals generated from the rapid decomposition of AM have a higher tendency to attack GMA molecules than PP chains. At the same estimated amount of primary radicals, both grafting degree and grafting efficiency increase with decreasing decomposition temperature of the initiator (for the same decomposition half-life) in the order of AM > benzoyl peroxide (BPO) > 2,5-di(t-butylperoxy)-2,5-dimethyl-3-hexyne (LPO). FunctionalizedPP with the desired grafting degree and little degradation of PP could be obtained by the use of mixed initiators. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1957–1963, 1998     

马来酸酐悬浮固相接枝聚丙烯

采用悬浮固相法制备出马来酸酐接枝聚丙烯。研究了单体用量、界面剂种类和用量、助交联剂、体系 pH值等因素对马来酸酐接枝率的影响。实验发现,随着单体用量增加,接枝率虽然逐渐增大,但单体接枝效率显著下降。界面剂的添加量对接枝率也有较大影响,适宜的添加量可以提高接枝率,采用二甲苯作界面剂时,其用量比甲苯少。添加适量的助交联剂有助于提高接枝率。另外,体系pH值的改变也会影响接枝率。     

Properties and Characterization of Filled Poly(Propylene) Composites Crosslinked Through Siloxane Linkage

Summary: The silane‐grafting and water‐crosslinking of poly(propylene) (PP) and its composites with calcium carbonate are described. Particular consideration is made on the properties and characterization of the grafted‐ and crosslinked‐products. Silane‐grafting of the polymers was performed in the melt by the use of vinyltrimethoxysilane and dicumyl peroxide. The results show that during the grafting process, PP chain‐scission was accompanied as a side reaction. Peroxide concentration was found to be a major factor in determining the extents of grafting and PP degradation. After conducting a crosslinking reaction, the degree of crosslink determined from the direct measurement of gel content and indirect method by evaluating FTIR data was compared. The effects of silane crosslink on the thermal and mechanical properties of the PP composites were discussed. A combined effect of filler and silane crosslink network in enhancing composite modulus, tensile stress, heat distortion, and decomposition temperatures is evident.

Formation of stable siloxane linkages.     

马来酸酐改性聚丙烯的交联副反应

用加入助剂和不加助剂的马来酸酐(MAH)熔融接枝改性聚丙烯(PP)。研究了单体MAH、引发剂过氧化二异丙苯(DCP)和助剂亚磷酸三苯酯(TPP)用量对PP交联的影响。PP交联副反应是由DCP引发生成的PP大分子自由基和由MAH激态分子生成的PP大分子自由基而产生的。TPP含有给电子体,可减小PP分子中甲基产生的正电诱导效应倾向,阻止PP发生分子内自由基的转移反应和分子间的转移反应,减小PP的交联;TPP化合物中含有磷原子,它与MAH的激态分子产生电子转移作用,使MAH的激态分子浓度减小,从而减少PP的交联。     

PP改性加工工艺的研究现状

总结了近年来聚丙烯改性的方法及加工工艺。介绍了通过共聚、接枝、交联、填充母料、填充或增强改性、共混改性或其他方法(加入成核剂等)对聚丙烯进行的改性，其中，共混改性是聚丙烯改性应用最广的技术。另外，还重点阐述了聚丙烯共混改性的加工工艺。     

聚丙烯改性研究进展

介绍了目前广泛采用的聚丙烯改性研究方法：接枝、交联、增强（填充）、共混等。同时就茂金属催化剂在共聚改性中的应用及纳米粒子改性PP的新技术作了介绍。     

Controlled degradation and crosslinking of polypropylene induced by gamma radiation and acetylene

Isotactic polypropylene (iPP) undergoes crosslinking and extensive main chain scissions when submitted to irradiation. The simultaneous irradiation of PP and acetylene is able to control chain scission and produce grafting. The grafted PP further reacts with PP radicals resulting in branching and crosslinking. In this work, commercial polypropylenes (iPP) of different molecular weights were irradiated with a ⁶⁰Co source at dose of 12.5 kGy in the presence of acetylene in order to promote the crosslinking. The mechanical and rheological tests showed a significant increase in melt strength and drawability of the modified samples obtained from resins with high melt flow index. The characterization of the molecular modifications induced by gamma irradiation of isotactic polypropylenes under acetylene atmosphere proved the existence of branching, crosslinking and chain scission in a qualitative way. The G′ and G″ indicated the presence of LCB in all samples. Therefore, PP irradiation under acetylene was proved to be an effective approach to achieve high melt strength polypropylene (HMSPP).