摘要
采用Ziegler-Natta催化剂制备的线性结构聚丙烯（PP）是一种综合性能优良的通用塑料，应用十分广泛。但传统工艺生产的线性PP在需要高流动性的薄壁注塑成型和高熔体强度的热成型等领域受到限制。工业上常采用过氧化物引发PP反应挤出的方法，对PP的流动性和分子结构进行调控，但过氧化物及其副产物的残留会造成PP品质的降低，并大大减少PP制品的使用寿命。本文针对以上缺点，创新性的利用具有强氧化特性以及反应后无残留的臭氧（O3）气体替代有机过氧化物，引发PP反应挤出，对PP 进行了可控流变改性和长链支化改性的研究，具体研究内容和结果如下：（1）在PP的熔融挤出过程中引入O3，可以高效的引发PP产生自由基，导致大分子链发生氧化和断链反应，制备了可控流变聚丙烯（CR-PP）。CR-PP的熔融指数和流变学结果表明，喂料速度越低、主机螺杆转速越高、挤出温度越高，PP降解程度越大，流动性越高。因此，可以通过挤出机参数调控PP的分子量和分子量分布，获得所需流动性的PP。
reactive to（2）在O3氧化PP的反应挤出过程中，添加多官能度单体三羟甲基丙烷三丙烯酸酯（TMPTA），利用O3引发的大分子自由基引发长链支化反应，成功制备了长支链聚丙烯（LCB-PP），最大支化点密度达到0.495/1000 C。实验中成功制备的LCB-PP，具有较高的弹性、较高的零剪切黏度、较低的损耗系数和较长的松弛时间；熔体拉伸测试中表现出了明显的应变硬化现象，熔体强度有所提高；结晶温度和熔融温度较纯PP有所提高，晶粒发生细化；力学性能较纯PP也有所提高。LCB-PP的流变学数据表明，单体含量过低、挤出温度过高、喂料速度过低以及主机螺杆转速过高使PP的断链反应为主反应，导致长链支化反应程
度较低。
（3）为更灵活的调节LCB-PP的支化度，探究支化单体官能度的不同对聚丙烯支化反应过程和支化产物结构的影响，在反应挤出过程中分别添加了单官能度单体（GMA）和双官能度单体（HDDA）。探究发现，在实验用量范围内，PP与GMA发生接枝反应，但没有生成长链支化结构；在较高的HDDA含量下（2.0wt%以上），HDDA有效的引发PP形成长链支化结构，最大支化点密度达到0.346/1000 C；但在较低含量下（1.0wt%以下），HDDA不能有效的引发PP形成长链支化结构。
关键词：聚丙烯；臭氧氧化；反应挤出；可控流变；长链支化
Abstract
Polypropylene (PP) which is produced via Ziegler–Natta or metallocene catalysis is one of the commodity polymers with the largest share in the present market. Due to the poor flowability and low melt strength of linear PP, it is limited in thin-wall injection molding and thermoforming. Reactive extrusion using peroxides as a radical initiator is the most commonly approach to regulated the flowability and molecular structure of PP. But utilizing organic peroxide as initiator has its own disadvantages, namely, limited controllability and easily excessive and non-homogenous degradation in PP. This thesis reports a novel synthesis method to prepare controlled-rheology PP (CR-PP) and lon
g-chain branched PP (LCB-PP) via in-situ ozonolysis during reactive extrusion with or witout multifunctional agent. The specific contents are as follows:
(1) CR-PP was obtained via in-situ ozonolysis during reactive extrusion in just several seconds period. The results of the melt flow index (MFI) and rheological measurement experiments showed that the higher polymer throughput, screw speed and reactive temperature, the lower MFI of CR-PP. Thus, we can adjust the processing parameters to control the desired flowability of CR-PP.
(2) LCB-PP was obtained via in-situ ozonolysis during reactive extrusion in the presence of multifunctional agent, trimethylolpropane triacrylate (TMPTA). The maximum branching point density of the LCB PP was 0.495/1000C. LCB-PP showed a significant influence on the viscoelastic properties of the melts, such as high elasticity, high zero shear viscosity, low loss coefficient and long relaxation time. The LCB-PP samples showed a distinct strain hardening behavior in elongational flow with changing strain rate dependence. The crystallization and melting temperatures of LCB-PP were higher than virgin PP. The results of WAXS indicating that the incorporation of LCBs did not change the crystal structure of PP backbones, but the grain became smaller. Thus the incorporation of LCBs improved mechanical properties of PP. By analysing the rheological measurement, the low TMPTA concentration, high extrusion temperature, low feeding speed and high screw speed accelerated degra
dation and the LCB PP could not be prepared.
（3）To adjust of the degree of branching of LCB-PP , we used the monofunctional agent (GMA) and bifunctional agent (HDDA). The different functionalities of multifunctional agent effected on the branching reaction process and branching structure of polypropylene. It was found that PP grafted GMA (PP-g-GMA) was obtained via in-situ ozonolysis during reactive extrusion in the presence of GMA. At high HDDA concentration (2.0wt% or more), it can effectively initiate PP to form long chain. It couldn’t effectively initiate PP to form long chain branched structure, at low concentration (1.0wt% or less) of HDDA. The results of GPC showed that the maximum branching point density of the LCB PP was 0.346/1000C.
Keywords:PP; Ozone oxidation; Reaction Extrusion; Long-Chain Branching
目录
摘要 .............................................................................................................................................. I Abstract ............................................................................................................................................ I I 第一章绪论.. (1)
1.1聚丙烯简介 (1)
1.1.1 聚丙烯的发展 (1)
1.1.2 聚丙烯的结构及特点 (1)
1.1.3 聚丙烯的高性能化 (2)
1.2 高流动聚丙烯的概述 (2)
1.2.1 高流动聚丙烯的分类 (3)
1.2.2 高流动聚丙烯的制备方法 (3)
1.3 长支链聚丙烯的概述 (5)
1.3.1 长支链聚丙烯性能特点 (5)
1.3.2 长支链聚丙烯制备方法 (6)
1.3.3 长支链聚合物的表征手段 (11)
1.3.4 长支链聚丙烯的应用 (13)
1.4 臭氧氧化聚合物改性概述 (14)
1.4.1 臭氧的简介 (14)
1.4.2 臭氧氧化橡胶的研究现状 (15)
1.4.3 臭氧氧化塑料的研究现状 (15)
1.5本文研究意义与主要内容 (15)
1.5.1 研究意义 (15)
1.5.2 研究内容 (16)
第二章实验部分 (17)
2.1实验原料 (17)
2.2实验设备及仪器 (17)
2.3 实验工艺流程 (18)
2.3.1实验设备图 (18)
2.3.2 O3氧化引发可控流变聚丙烯样品的制备 (18)
2.3.3 O3氧化引发支化聚丙烯样品的制备 (18)
2.3.4结构表征与性能测试 (19)
2.4本章小结 (21)
第三章臭氧氧化的反应挤出过程制备可控流变聚丙烯 (22)
3.1喂料速度对可控流变PP的影响 (22)
3.1.1 PP臭氧化反应原理及产物的FTIR分析 (22)
3.1.2流变学分析 (24)
3.1.3 DSC分析 (27)
3.1.4力学性能分析 (29)
3.2螺杆转速对可控流变PP的影响 (29)
3.2.1流变学分析 (29)
3.2.2 DSC分析 (31)
3.2.3力学性能分析 (32)
3.3挤出温度对可控流变PP的影响 (32)
3.3.1流变学分析 (32)
3.3.2 DSC分析 (34)
3.3.3力学性能分析 (35)
3.4本章小结 (36)
第四章三官能度单体长链支化聚丙烯的制备及表征 (37)
4.1 TMPTA长链支化PP的反应机理及产物的FTIR分析 (37)
4.2 GPC及凝胶含量分析 (39)
4.3线性粘弹性行为分析 (41)
4.3.1稳态柔量 (41)
4.3.2动态频率扫描 (42)
4.3.3 Cole-Cole图 (45)
4.3.4 vGP图 (45)
4.3.5加权松弛谱 (46)
4.4拉伸流变行为分析 (47)
4.5长支链结构对PP结晶性能的影响 (48)
4.5.1 DSC分析 (48)

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