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。     

SSA热分级技术在表征IPC各组分相互作用中的应用

对典型抗冲共聚聚丙烯(IPC)进行了溶剂分级,分级出三组分,即乙烯-丙烯无规共聚物(EPR)、乙烯-丙烯嵌段共聚物(EbP)、丙烯均聚物(PPH)。通过连续自成核与退火(SSA)热分级技术分析了IPC,EbP/EPR,EbP/PPH二元非共混物和溶液共混物的结晶行为。采用扫描电子显微镜观察了PPH/EPR二元、PPH/EPR/EbP三元溶液共混物的冲击断面。结果表明:SSA热分级技术对分析IPC及其分级出的各级分的异质性具有较好的分辨效果;EbP和PPH组分易形成共晶,而EPR对EbP的结晶起到了稀释和弱化作用,从而证明EbP和PPH,EbP和EPR之间均存在相互作用;PPH/EPR溶液共混物中加入EbP后,冲击断面出现韧性断裂,说明EbP起到了增容PPH基体和分散相EPR的作用。     

Spheripol工艺生产高抗冲聚丙烯

介绍了Spheripol工艺生产高抗冲聚丙烯产品的方法,采用两步复合工艺生产嵌段聚丙烯,第1步采用环管反应器进行丙烯液相均聚反应,第2步采用流化床反应器进行丙烯均聚物与乙烯单体气相共聚反应,即在气相反应器中,利用来自环管反应器中的均聚物的残余活性,加入乙烯和补充的丙烯及氢气实现乙-丙共聚,共聚物的生成使最终产品的抗冲性能大大提高,尤其是低温下的抗冲性能。     

^13C-NMR在抗冲共聚聚丙烯序列结构研究中的应用

论述了^13C-NMR在抗冲共聚聚丙烯序列结构研究中的进展。介绍了抗冲共聚聚丙烯N脉谱图及谱图归属和单元组的分布、组成及数均序列长度的计算方法。研究结果表明抗冲共聚聚丙烯主要是由乙丙无规共聚物、乙丙可结晶共聚物（富含乙烯或丙烯均可能存在）和聚丙烯均聚物组成。     

给电子体对VOCl_3/Al_2Et_3Cl_3催化的乙丙橡胶结构和性能的影响

采用VOCl_3/Al_2Et_3Cl_3体系催化乙烯-丙烯共聚合合成乙丙橡胶(EPR),考察了给电子体苯甲酸乙酯和邻苯二甲酸二异丁酯对EPR结构和性能的影响。结果表明,少量给电子体的加入可以明显提高VOCl_3/Al_2Et_3Cl_3催化乙烯-丙烯共聚合的催化活性,随着给电子体加入量的增大,催化活性反而下降; 给电子体的加入并未引入结晶的长序列乙烯嵌段,仅提高了产物的相对分子质量; 给电子体的加入提高了丙烯单体的共聚能力,使EPR的丙烯结合量增加。     

聚丙烯结构形态对性能的影响

用红外光谱、动态粘弹谱、透射电镜、X光衍射仪、DSC、偏光显微镜和机械力学性能测试仪等手段对均聚、嵌段共聚、无规共聚PP进行了结构、形态与性能关系的研究。结果表明,嵌段共聚物中乙烯在红外谱图中显示两个特征峰,而无规共聚物中乙烯只出现—个特征峰。研究还证明,PP嵌段共聚物是PP、PE、EPR多元组分的共混物。PE包含在EPR中以球形无规地分散在PP基体中。EPR的含量是提高PP共聚物冲击性能的决定因素。无规共聚物形态接近均相体系,其冲击强度小于嵌段共聚物而大于均聚物。     

乙丙嵌段共聚物相对分子质量及链结构对PP/EPR共混体系结构与性能的影响

设计合成了一系列不同相对分子质量和乙烯平均序列长度的乙丙嵌段共聚物（EP）,并将其作为聚丙烯（PP）/二元乙丙橡胶（EPR）共混体系的增容剂,考察了EP用量、相对分子质量及乙烯平均序列长度对共混体系性能及分散相形态演变的影响。结果表明,EP增容PP/EPR体系时存在最佳添加量,少量EP的加入可有效提高PP/EPR共混体系的抗冲击性能,并对分散相尺寸及形态起到良好的调控作用;同时,EP的相对分子质量越大对共混体系的冲击性能提高越明显,EP的组成与EPR越接近,对共混体系的增容效果越明显。     

新型丙烯-乙烯共聚物增韧聚丙烯的研究

丙烯-乙烯共聚物Vistamaxx（VM）是一种丙烯摩尔含量占70％以上的新型弹性体。用VM增韧聚丙烯（PP），考察了PP／VM共混物的力学性能、微观形态结构以及结晶性能，并与乙烯-辛烯共聚物（POE）与PP的共混体系进行了对比。结果表明，常温下VM增韧效果优于POE，PP／VM体系拉伸性能优于PP／POE体系；VM在PP中表现出比POE更好的分散性；VM具有与PP相同的晶型，VM的加入细化了PP的晶粒。     

高抗冲改性聚丙烯树脂的研究

采用均聚PP为基料,通过在均聚PP与乙烯—丙烯—二烯三元共聚物(EPDM)的共混物中加入第三组分——增容剂,再配合一定粒度的适量的滑石粉,研制出适用于制作轿车保险杠的高抗冲改性PP树脂组成物,并就其组成、用量、组分间熔融粘度差以及共混物形态等条件对性能的影响作了初步的探讨。     

用于烯烃均聚和共聚的新型催化剂 VO(P204)2/Et3Al2Cl3

研究了VO(P204)2配合物与Et3Al2Cl3,组成的催化剂作用下的乙烯均聚和乙烯／丙烯共聚。VO(P204)2催化剂聚合乙烯的活性及其活性中心的寿命均高于VOCl3催化剂,并具有良好的氢调敏感性,既可使乙烯、丙烯进行无规共聚,又可使乙烯、丙烯和乙叉降冰片烯进行三元共聚。     

Partial replacement of EPR by GTR in highly flowable PP/EPR blends: Effects on morphology and mechanical properties

This research analyzes the effect of ground tire rubber (GTR) and a novel metallocene‐based ethylene–propylene copolymer (EPR), with high propylene content, on the morphology and mechanical behavior of ternary polymer blends based on a highly flowable polypropylene homopolymer (PP). The PP/EPR blends morphology, with very small domains of EPR dispersed in the PP matrix, indicates a good compatibility among these materials, which leads to a significant improvement on elongation at break and impact strength. The incorporation of EPR on the rubber phase of thermoplastic elastomeric blends (TPE) based on GTR and PP (TPE^GTR) has a positive effect on their mechanical performance, attributed to the toughness enhancement of the PP matrix and to the establishment of shell‐core morphology between the rubber phases. The mechanical properties of the ternary blends reveal that TPE^GTR blends allow the upcycling of this GTR material by injection molding technologies. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42011.     

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     

PP-HDPE-EPR三元共混体力学性能的研究

研究了乙丙橡胶（EPR）对于乙丙橡胶、高密度聚乙烯（HDPE）和聚丙烯（PP）三元共混体的增韧作用和共混体混炼时间对力学性能的影响。实验表明，该共混体简支梁缺口冲击强度比纯聚丙烯提高5倍以上。     

Influence of copolymerization conditions on the structure and properties of polyethylene/polypropylene/poly(ethylene‐co‐propylene) in‐reactor alloys synthesized in gas‐phase with spherical ziegler‐natta catalyst

A spherical TiCl₄/MgCl₂‐based catalyst was used in the synthesis of polyethylene/polypropylene/poly (ethylene‐co‐propylene) in‐reactor alloys by sequential homopolymerization of ethylene, homopolymerization of propylene, and copolymerization of ethylene and propylene in gas‐phase. Different conditions in the third stage, such as the pressure of ethylene–propylene mixture and the feed ratio of ethylene, were investigated, and their influences on the compositions, structural distribution and properties of the in‐reactor alloys were studied. Increasing the feed ratio of ethylene is favorable for forming random ethylene–propylene copolymer and segmented ethylene–propylene copolymer, however, slightly influences the formation of ethylene‐b‐propylene block copolymer and homopolyethylene. Raising the pressure of ethylene–propylene mixture results in the increment of segmented ethylene–propylene copolymer, ethylene‐b‐propylene block copolymer, and PE fractions, but exerts a slight influence on both the random copolymer and PP fractions. The impact strength of PE/PP/EPR in‐reactor alloys can be markedly improved by increasing the feed ratio of ethylene in the ethylene–propylene mixture or increasing the pressure of ethylene–propylene mixture. However, the flexural modulus decreases as the feed ratio of ethylene in the ethylene–propylene mixture or the pressure of ethylene–propylene mixture increases. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2481–2487, 2006     

Compatibility and tensile behavior of polypropylene/ethylene-propylene rubber blends

This study clarifies and quantifies factors which increase the ductility of a low-molecular-weight propylene homopolymer having an intrinsic viscosity of 0.89 dl/g. The tensile behavior of homopolymer/ethylene-propylene rubber (EPR) blends was studied from the viewpoint of the associated molecular structure of EPR and its compatibility with the homopolymer. When EPR is “dissolved” in a homopolymer, the glass transition temperature (T_g) of the amorphous phase of a homopolymer was found to shift to a lower temperature, with homopolymer/EPR compatibility being subsequently evaluated using this shift, i.e., Δt_g. Results show two conditions are required to improve the ductility of the low-molecular weight propylene homopolymer: ΔT_g must be ≥ 3°C and ≥ 30 wt% EPR must be blended with the homopolymer.     

气相法PP洗衣机专用树脂结构与性能研究

以核磁共振碳谱、差示扫描量热法、凝胶渗透色谱，扫描电子显微镜和原子力显微镜等手段对聚丙烯共聚物进行结构与性能研究，发现气相法聚丙烯聚物中含有更多的乙丙接点及多种乙丙嵌段结构，分子链柔性好，其分子量分布宽，乙丙橡胶的重均分子量较大，粒径较小，分散均一，对提高冲击强度有利，其结晶细密，结晶温度高，速度快、对提高刚性，改善加工性能有利。     

The Use of Ethylene/Propylene Copolymers as Compatibilizers for Recycled Polyolefin Blends

Compatibilizing effects of ethylene/propylene (EPR) diblock copolymers on the morphology and mechanical properties of immiscible blends produced from recycled low‐density polyethylene (PE‐LD) and high‐density polyethylene (PE‐HD) with 20 wt.‐% of recycled poly(propylene) (PP) were investigated. Two different EPR block copolymers which differ in ethylene monomer unit content were applied to act as interfacial agents. The morphology of the studied blends was observed by scanning‐ (SEM) and transmission electron microscopy (TEM). It was found that both EPR copolymers were efficient in reducing the size of the dispersed phase and improving adhesion between PE and PP phases. Addition of 10 wt.‐% of EPR caused the formation of the interfacial layer surrounding dispersed PP particles with the occurrence of PE‐LD lamellae interpenetration into the layer. Tensile properties (elongation at yield, yield stress, elongation at break, Young's modulus) and notched impact strength were measured as a function of blend composition and chemical structure of EPR. It was found that the EPR with a higher content of ethylene monomer units was a more efficient compatibilizer, especially for the modification of PE‐LD/PP 80/20 blend. Notched impact strength and ductility were greatly improved due to the morphological changes and increased interfacial adhesion as a result of the EPR localization between the phases. No significant improvements of mechanical properties for recycled PE‐HD/PP 80/20 blend were observed by the addition of selected block copolymers.