固相法制备高熔体强度聚丙烯

发布时间：2018-07-08 20:29

  本文选题：聚丙烯 + 溶胀　； 参考：《东北石油大学》2017年硕士论文

【摘要】：高熔体强度聚丙烯研究开始于上世纪八十年代,高熔体强度聚丙烯的熔体强度高并且具有明显的应变硬化现象,从而聚丙烯在挤出涂布、发泡和热成型中得到了广泛的应用,因此对于高熔体强度聚丙烯的研究具有重要的意义。本课题的研究目标是制备高熔体强度聚丙烯,掌握制备高熔体强度聚丙烯的相关技术和工艺过程。课题研究的关键是在聚丙烯大分子主链上引入适当的交联结构和长支链结构以提高熔体强度以及对降解反应的控制。本文采用溶剂浸渍协助PP固相交联接枝法制备高熔体强度聚丙烯,以乙醚为溶胀剂,二乙烯基苯(DVB)为单体,过氧化苯甲酰(BPO)为引发剂,可以显著提高聚丙烯的熔体强度,考察了溶胀剂用量、溶胀时间、溶胀温度、单体和引发剂用量、界面剂用量、粒径、反应时间和反应温度等因素对改性产品的熔体强度、熔体流动速率和凝胶含量的影响,并采用TG、FTIR、PLM、XRD和DSC等对产品进行了表征。研究结果表明,当按照PP:DVB:BPO的质量比为100:0.2:0.03投料,用20 ml溶胀剂在30℃溶胀10 h后,再在100℃反应2 h获得产物的熔体强度最大值(6.4 kPa.s),比原PP的MS提高11倍,与未溶胀的相比,MS提高了4.9 kPa·s,说明使用溶剂浸渍协助PP固相接枝过程中,引发剂和单体进入聚丙烯颗粒内部可以有效提高产物的MS,弥补了传统固相反应主要在PP颗粒表面进行,单体分布不均匀的缺点。红外结果表明,DVB单体成功接枝到PP主链上;通过DSC和PLM表征分析可知,支化交联结构促进了结晶作用,使结晶温度变高,结晶度变小。球晶变小,数量变多,边界变模糊;热重分析可知,与纯PP相比,改性产品的热稳定性有所提高;通过XRD表征可知,改性后的高熔体强度聚丙烯没有改变其晶型,仍与普通聚丙烯相同为单斜晶系的α晶型结构。其次采用双单体1,6-己二醇二丙烯酸酯(HDDA)-DVB成功制备了高熔体强度聚丙烯,考察了在体系中共单体HDDA含量对改性聚丙烯的凝胶含量、熔体流动速率和熔体强度的影响并对改性后产品进行了表征。当w(DVB)/w(HDDA)=1/2时,熔体强度最大,达到10 kPa·s;在不同HDDA用量下,改性后的熔体强度随着HDDA用量的增加而增大,而对凝胶含量的影响不大。红外表征可知,双单体HDDA和DVB成功接枝到PP主链上;通过热重表征可知,体系中HDDA单体的加入使改性PP的热稳定性进一步提高。通过XRD表征可知,体系中HDDA单体的加入没有改变产品的晶型,其晶型与普通聚丙烯相同,即均为单斜晶系的α晶型结构。
[Abstract]:The research of high melt strength polypropylene began in 1980s. The melt strength of high melt strength polypropylene is high and has obvious strain hardening phenomenon, so polypropylene has been widely used in extrusion coating, foaming and hot forming. Therefore, the study of high melt strength polypropylene is of great significance. The purpose of this paper is to prepare high melt strength polypropylene and to master the relevant technology and process of preparing high melt strength polypropylene. The key of the research is to introduce appropriate cross-linking structure and long branched chain structure into the main chain of polypropylene macromolecule in order to improve the melt strength and control the degradation reaction. In this paper, high melt strength polypropylene was prepared by solvent impregnation assisted by solid phase crosslinking grafting of PP. The melt strength of polypropylene was significantly improved by using ether as swelling agent, divinylbenzene (DVB) as monomer and benzoyl peroxide (BPO) as initiator. The effects of the amount of swelling agent, swelling time, swelling temperature, amount of monomer and initiator, amount of interfacial agent, particle size, reaction time and reaction temperature on the melt strength, melt flow rate and gel content of the modified product were investigated. The products were characterized by XRD and DSC. The results showed that when the mass ratio of PP: DVB: BPO was 100: 0.2: 0.03, the maximum melt strength (6.4 KPA 路s) of the product was obtained after swelling at 30 鈩，

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