高流动抗冲共聚PP的相态结构

用扫描电子显微镜和偏光显微镜．对氢调法和降解法生产的高流动抗冲共聚聚丙烯(PP)的微观结构进行了分析．特别对其中橡胶相在PP中的形状、尺寸和分布进行了研究。通过进行刻蚀条件的选择,分析比较不同PP中橡胶相微观结构的差异．找出了2种方法生产PP的最佳刻蚀条件。同时．对庚烷及癸烷的可溶物和不溶物做偏光显微分析。结果表明：降解法生产的PP橡胶相中确实存在少量可结晶的聚乙烯链段;在PP链上存在乙丙橡胶链嵌段。     

CPP薄膜专用三元共聚聚丙烯的结构与性能

分析了流延聚丙烯薄膜专用二元无规共聚聚丙烯W0723F与3种三元无规共聚聚丙烯的基本热力学性能、凝聚态结构、相对分子质量及其分布、结晶性能及流变性能。结果表明:二元无规共聚聚丙烯弯曲模量高,熔点高;3种三元无规共聚聚丙烯中1-丁烯含量相差不大,摩尔分数为5.1%~5.4%,乙烯含量相差较为明显,摩尔分数为3.0%~9.0%;两种进口产品的分子链序列结构中包含乙烯共聚链段,熔点低、熔融峰宽、晶体粒径小,产品具有较低的起始热封温度;流变性能分析表明,国产产品的加工流动性较好。     

氯化乙丙共聚物的红外光谱分析

用钛系高效催化剂进行乙烯—丙烯共聚合,得到乙烯、丙烯摩尔比分别为1∶1和2∶1的两个乙丙共聚物,共聚物大分子链主要由聚乙烯和聚丙烯链段构成,聚丙烯链段的等规性很低。共聚物的氯化产物的红外光谱具有氯化聚乙烯和氯化聚丙烯的特征吸收。通过分析,确定了含各种C-Cl键链节的化学结构类型,并讨论了避免产生氯化共聚产物中含甲苯不溶物的问题.     

乙烯含量对透明无规共聚聚丙烯性能的影响

对国内市场已普遍认可的6种透明无规共聚聚丙烯的乙烯含量进行测试,确定了适合透明无规共聚聚丙烯的最佳乙烯含量。选择乙烯含量不同的无规共聚聚丙烯,考察乙烯含量对无规共聚聚丙烯力学性能、光学性能、溶出物含量的影响。结果表明:随着乙烯含量的增加,无规共聚聚丙烯的分子结构混乱度增加,熔融焓、透明性、韧性提高,熔点降低。同时,无规共聚聚丙烯中的二甲苯可溶物、正己烷提取物含量提高。     

高流动高刚抗冲共聚聚丙烯聚合工艺与结构和性能关系研究

采用两步法在Spheripol聚丙烯中试装置进行高流动高刚抗冲共聚聚丙烯中试开发，获得三种刚韧平衡的中试产品。对产品进行力学性能、乙烯含量、橡胶相含量、DSC测试，采用偏光显微镜（POM）、扫描电子显微镜（SEM）对结晶及脆断面形貌进行观察。结果表明：提高产品中乙烯含量、降低气相反应器中气相比和氢气/乙烯比、提高橡胶相的分子量、细化橡胶相尺寸、改善橡胶相的分散性，均有利于提高产品的冲击强度。降低橡胶相含量、细化球晶尺寸、提高产品结晶度，尤其是均聚部分的结晶度有利于提高产品刚性。降低中试气相比，将产品的乙烯含量控制在4.5%左右，橡胶相含量为9.5%左右，橡胶相尺寸为0.5μm左右，可获得刚韧平衡的高流动高刚抗冲共聚聚丙烯产品。     

高流动性抗冲共聚聚丙烯树脂的开发

采用流变改性工艺生产高流动性抗冲共聚聚丙烯树脂,通过研究母料添加量、乙烯含量、加工温度等因素对树脂性能的影响,实现对流变改性工艺的有效控制,获得流动性和抗冲击性能优异的高流动性抗冲共聚聚丙烯。     

乙烯-1-丁烯共聚物为橡胶相的抗冲共聚聚丙烯的结构

通过核磁共振波谱仪、凝胶渗透色谱仪、差示扫描量热仪、扫描电子显微镜等对乙烯-1-丁烯共聚物为橡胶相的抗冲共聚聚丙烯的结构进行了分析,并测试了其模塑收缩率及耐应力发白性能。结果表明:乙烯-1-丁烯共聚物可溶物的相对分子质量较低时,所制抗冲共聚聚丙烯在注塑过程中易受到剪切应力作用而沿熔体流动方向形成柱状取向结构,此橡胶相取向结构赋予抗冲共聚聚丙烯低模塑收缩率和良好的耐应力发白性能;乙烯-1-丁烯共聚物可溶物的相对分子质量较高时,所制抗冲共聚聚丙烯在注塑过程中则呈现典型的"海-岛"状橡胶形态,因而表现出较高的模塑收缩率和较差的耐应力发白性能。     

抗冲击共聚聚丙烯的结构与性能

对3种抗冲击共聚聚丙烯的力学性能进行了研究,并且采用动态力学分析、二甲苯溶出、溶胶凝胶渗透色谱和核磁共振等方法分析了抗冲共聚聚丙烯结构对其力学性能的影响。结果表明:提高共聚聚丙烯中乙丙橡胶相和聚丙烯基体之间的相容性,增加橡胶相含量,增大相对分子量并使其分布较窄,增加橡胶相中乙丙无规共聚物含量均有利于提高共聚聚丙烯的冲击强度。     

透明抗冲共聚聚丙烯的结构与性能对比

采用核磁共振碳谱、红外光谱、凝胶渗透色谱、差示扫描量热法等研究了透明抗冲共聚聚丙烯、普通无规共聚透明聚丙烯、抗冲共聚聚丙烯的结构与性能。结果表明:透明抗冲共聚聚丙烯的乙烯含量介于普通无规共聚透明聚丙烯和抗冲共聚聚丙烯之间,橡胶相含量高于普通无规共聚透明聚丙烯,橡胶相的重均分子量较小,粒径小于0.4 μm,分散均一,有利于保持透明性和提高抗冲击性能,可满足低温透明包装应用的需求。     

抗冲共聚聚丙烯在Novolen装置上的生产

对Novolen工艺中抗冲共聚聚丙烯生产的共聚反应机理、产品质量控制原理、工艺调节措施进行了综述。影响抗冲共聚物产品质量的主要因素有均聚物MFR、粉料总MFR、乙烯总含量和橡胶相中乙烯含量。只有对每个影响因素进行仔细选择和控制才能得到高质量的抗冲共聚聚丙烯产品。此外,以抗冲共聚聚丙烯2500H生产为例,对抗冲共聚聚丙烯产品的生产过渡步骤进行了研究,并对得到的产品进行了分析讨论。     

抗冲聚丙烯管材专用树脂的结构与性能

研究了乙丙嵌段共聚聚丙烯(PP-B)管材专用树脂的结构与性能。PP-B具有典型的乙丙嵌段共聚物序列结构,是含有丙烯均聚物(PP-H)、乙丙橡胶(EPR)及可结晶乙丙共聚物的抗冲聚丙烯(PP);其中,均聚物与共聚物比例合理,形成的EPR多、粒径小,对提高冲击强度有利。提高PP-H的质量分数和等规指数,可有效提高PP- B的刚性。PP-B的熔点与PP-H近似;相对分子质量分布较宽,流变性能好;微观与亚微观结构合理,宏观性能优良。     

Structure and morphology of a commercial high‐impact polypropylene in‐reactor alloy synthesized using a spherical Ziegler–Natta catalyst

A commercial high‐impact polypropylene (hiPP) was fractionated by temperature‐gradient elution fractionation into nine fractions. All fractions were studied using Fourier transform infrared spectroscopy and differential scanning calorimetry. The amount of ethylene in the fractions was also determined. The results demonstrate that the ethylene–propylene statistical copolymer (or ethylene–propylene rubber, EPR) content in this hiPP is rather low and the amounts of ethylene–propylene segmented copolymer and ethylene–propylene block copolymer (that act as adhesive and compatibilizer between elastomeric phase and matrix, respectively) are negligible. Furthermore, the morphology of the resin was studied using scanning electron microscopy observations of microtome‐cut original and etched samples, which reveals that EPR particles are too large and their distribution inside the matrix is not uniform. Copyright © 2010 Society of Chemical Industry     

Effect of the structure on the morphology and spherulitic growth kinetics of polyolefin in‐reactor alloys

Four polyolefin in‐reactor alloys with different compositions and structures were prepared by sequential polymerization. All the alloys were fractionated into five fractions: a random copolymer of ethylene and propylene (25°C fraction), an ethylene–propylene segmented copolymer (90°C fraction), an ethylene homopolymer (110°C fraction), an ethylene–propylene block copolymer (120°C fraction), and a propylene homopolymer plus a minor ethylene homopolymer of high molecular weight (>120°C fraction). The effect of the structure on the morphology and spherulitic growth kinetics of the polypropylene (PP) component in the alloys was investigated. The polyolefin alloys containing a suitable block copolymer fraction and a larger amount of PP had a more homogeneous morphology, and the crystalline particles were smaller. Quenching the polyolefin alloys led to smaller crystallites and a more homogeneous morphology as well. Isothermal crystallization was carried out above the melting temperature of polyethylene, and the growth of PP spherulites was monitored with polarized optical microscopy with a hot stage. The alloys with higher propylene contents exhibited a faster spherulitic growth rate. The fold surface free energy was derived, and it was found that a large amount of block copolymer fractions and random copolymer fractions could reduce the fold surface free energy. The structure of the alloys also affected the crystallization regime of PP. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 632–638, 2005     

Structure and properties of impact copolymer polypropylene. I. Chain structure

In this work, impact copolymer polypropylene (ICPP) was fractionated into 4 fractions. ICPP and the 4 fractions were studied using Fourier transform infrared and ¹³C nuclear magnetic resonance analysis. The results demonstrate that fraction A is ethylene–propylene rubber, fraction B is ethylene–propylene (EP) segmented copolymer, fraction C is ethylene–propylene block copolymer, and fraction D is polypropylene with a few ethylene monomers in the chain. The differences in properties between different impact copolymer polypropylenes should be due to their fractions' differences in composition and chain sequence structure. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 93–101, 1999     

Structure and properties of impact copolymer polypropylene. II. Phase structure and crystalline morphology

In this work, an impact copolymer polypropylene (ICPP) was separated into 4 fractions, A, B, C, and D. The phase structure, thermal behavior, and crystalline morphology of the ICPP and its 4 fractions were studied thoroughly using scanning electron microscopy (SEM). Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and polarized light microscopy (PLM). Results of SEM and DMA show that ethylene–propylene rubber (EPR) and part of the ethylene–propylene segmented copolymer disperse as toughening particles in the ICPP. The size and size distribution of these particles are determined by chain structure of the fractions of ICPP. From fraction A to fraction D, the morphology changes from noncrystalline to semicrystalline gradually, as shown by DSC. DSC results also indicate that thermal behavior of the ICPP agrees greatly with its chain structure. PLM demonstrates that it is difficult for the ICPP to grow perfect spherulites, that is, partially, because the matrix of ICPP, fraction D, has defects in its macromolecular chain. Another cause is that there is a good compatible structure in the ICPP and so the noncrystalline component (including all fractions) hinders the growth of the spherulite. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 103–113, 1999     

Microdeformation mechanisms in propylene–ethylene block copolymer

Blends of propylene–ethylene block copolymer (PEB) and propylene homopolymer (PP) were prepared to give various rubber contents (4–20 wt %). By diluting the PEB with PP with molecular weight equal to that of the PEB matrix, molecular characteristics of all the blends were kept constant. The rubber particle size and size distribution of all the blends were almost constant, so that the interparticle distance decreased with increased rubber content. According to the observation of the fracture behavior at ?20°C, a brittle to ductile transition was found at the rubber content of 16 wt %. Microdeformation behavior of the blends was investigated in the region of brittle to ductile transition by using transmission electron microscopy. In the case of the brittle sample with low rubber content, crazing and voiding were observed. Whereas even in the ductile sample with high rubber content, crazing certainly took place before shear yielding. The origin of ductile fracture could possibly be attributed to the relaxation of strain constraint by the microvoids contained in the craze. © 1993 John Wiley & Sons, Inc.     

汽车专用聚丙烯树脂的研制

通过分子设计,确定了共聚聚丙烯中乙丙橡胶质量、乙烯含量、乙丙橡胶和共聚聚丙烯特性粘数等因素对其宏观性能的影响,并确定了各因素的最佳控制指标,在生产能力为40kt/a的工业装置上开发了本体法工艺汽车用共聚聚丙烯树脂。     

中流动抗冲聚丙烯结构与性能研究

选取3种市售中流动抗冲聚丙烯产品,分析了产品的乙烯含量、橡胶相含量、橡胶相的相对分子质量和橡胶相形貌;同时对3种产品的热性能和力学性能进行了测试。结果表明,乙烯含量决定了橡胶相含量,橡胶相含量和橡胶相的相对分子质量对产品的刚韧平衡性能起到重要作用;乙烯在橡胶相中的含量达到50 %以上才能起到良好的增韧作用;根据此结论可优化抗冲聚丙烯产品的结构和共聚物含量,达到最佳的刚韧平衡。     

Kinetics of short‐duration ethylene–propylene copolymerization with MgCl2‐supported Ziegler–Natta catalyst: Differentiation of active centers on the external and internal surfaces of the catalyst particles

Ethylene–propylene copolymerization with a TiCl₄/MgCl₂ type ZN catalyst was conducted for different durations from 30 to 600 s, and changes of polymerization rate, concentration of active centers ([C^*]) and copolymer chain structure with time were traced. The copolymerization rate decayed with time, but [C^*]/[Ti] increased in the same period. This was attributed to release of more active sites through disintegration of catalyst particles by the growing polymer phase. Ethylene content of the copolymer quickly decreased in the period of 30–90 s, meaning that the active centers activated in the reaction process have stronger ability of incorporating propylene than those activated at the very beginning. The copolymer samples were fractionated into two parts, namely n‐heptane soluble fraction (random copolymer) and insoluble fraction (segmented copolymer with high ethylene content). With continuation of the copolymerization, active centers producing the random copolymer chains increased much faster than active centers producing the segmented copolymer chains, and became the dominant centers after 120 s. Consequently, proportion of the soluble fraction sharply increased with time. All these results indicate that the active centers located on the external surface of catalyst particles are highly different from those buried inside the particles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46030.