Influence ofβ-nucleating Compound Agents on the Mechanical Properties and Crystallization Behavior of Polypropylene Random Copolymer

A novel polypropylene random(PPR)composite materials with optimized properties was developed by addingβ-nucleating compound agents(rare earth complex WBG-2 and aryl amide derivative TMB-5)and ternary compound modifier(TPE/WBG-2/CaCO_(3)).The effects of differentβ-nucleating agents and ternary compound modifier on the mechanical properties and crystallization behavior of PPR were analyzed.The results show that,compared with pure PPR materials,both WBG-2 and TMB-5 could significantly improve the impact strength of PPR.The crystallization temperature of PPR increased with the addition ofβ-nucleating agent.The modified PPR prepared with ternary compound modifier showed the most excellent comprehensive properties.

CHARACTERISTICS OF STRUCTURE OF IMPACT COPOLYMERS OF POLYPROPYLENE WITH LOW ETHYLENE CONTENTS

In the present work, the structure and impact properties of copolymers of polypropylenewith low ethylene contents have been investigated. Based on the results of ^(13)C--NMR, FTIR,WAXD, DSC, PLM and SEM, the relationship between impact properties and morphology of thecopolymers has been discussed. The high impact properties of copolymer ICP2 may attribute tothe relatively higher ethylene content and homogeneous ethylene unit distribution. The size andits distribution of spherulite in the copolymers and cycloid cavities dispersed in polypropylenecontinue phase may also be two important factors which affect the impact properties of these materials.

Critical Role of Ethylene-Propylene Block Copolymer in Impact Polypropylene Copolymer

Ethylene-propylene block copolymer(EbP) is a vital component in impact polypropylene copolymer(IPC), yet its distribution in the multiphase composite material and how it influences the phase structure and the mechanical properties are not well understood. In this work,four IPCs were investigated by atomic force microscopy-infrared(AFM-IR) to assess the phase compositions in situ, based on which in conjunction with the chain microstructure information obtained ex situ the distributions of the copolymer components were derived for each alloy. For the IPCs whose EbP comprises long P and long E segments, the EbP fraction was found to phase separate from the rubber and the PP matrix to form the cores of the disperse particles with the E-P segmented copolymer(EsP). In contrast, in the IPC with EbP composed of long P and short E segments, the EbP fraction formed an outer shell for the rubber particles with the cores comprising the EsP alone, and this IPC, containing a lower E comonomer content than its counterpart, exhibited both better impact resistance and higher flexural modulus. These results clarify how the chain structure of EbP governs the phase morphology in IPC, which in turn impacts the properties of the composite material.

INFLUENCE OF SHEARING ON IMPACT POLYPROPYLENE COPOLYMER:PHASE MORPHOLOGY,THERMAL AND RHEOLOGICAL BEHAVIOR

The influences of shearing conducted by a Brabender behavior of a commercial impact polypropylene copolymer （IPC） rheometer on phase morphology, thermal and rheological were studied. The crystallization and melting traces show that short-time annealing at 210℃ is unable to completely erase the influence of shearing on the samples. When the samples which were treated at a rotation speed of 80 r/rnin crystallize at a cooling rate of 10 K/min, their Tcs and corresponding Tms obviously rise with the increase of shearing time. Furthermore, the POM results reveal that the shearing can lead to the formation of shish-kebab and the shish-kebab amount is proportional to shearing time. The rheological measurement results show that the treated samples exhibit different G＇-ω dependences. The ＇second plateau＇ appears when the sample is treated at a rotation speed of 60 r/min or 80 r/min for 10 min, and linear G＇-ω dependence is observed at other rotation speeds. In addition, it is found that the appearance of the ＇second plateau＇ depends on the shearing time when the rotation speed is fixed. According to SEM observations, it is proposed that the ＇second plateau＇ of IPC samples should be ascribed to the aggregation of dispersion particles.

CCF/IPC层压板的制备与性能

以碳纤维(CF)和抗冲共聚聚丙烯(IPC)为原料,采用热压模塑工艺制得了连续CF增强IPC(CCF/IPC)层压板。研究了CF含量和预浸带铺放方式对CCF/IPC层压板冲击性能、弯曲性能和动态力学行为的影响。结果表明:当CF含量相同时,与0°/90°和编织铺放方式相比,采用0°铺放方式所得CCF/IPC层压板的冲击强度和弯曲强度均最高;当CF质量分数为40%,采用0°铺放方式时,CCF/IPC层压板的冲击强度和弯曲强度均达到最高,分别为141.9 kJ/m^(2)和388 MPa。随着CF含量的增加,CCF/IPC层压板的储能模量(E′)逐渐增大。当CF含量相同时,采用0°铺放方式所得CCF/IPC层压板的E′最高,0°/90°铺放方式次之,编织铺放方式最低。

CHARACTERIZATION OF IMPACT POLYPROPYLENE COPOLYMERS BY SOLVENT FRACTIONATION

The compositional heterogeneity of two impact polypropylene copolymers（IPCs） was studied by a combinatory investigation of temperature rising elution fractionation（TREF） and solvent fractionation.The chain structures and composition of fractions obtained from solvent fractionation were examined in detail.The TREF results shows that there are much more E-P segmented copolymer and more uniform distribution of ethylene sequence in IPC-1,which is responsible for its better comprehensive mechanical performance.The fractions from hexane and heptane are ethylene-propylene rubber phase and E-P block copolymers respectively.The result of solvent fractionation method also shows that custom hexane or heptane extractions can not extract the E-P copolymer completely.

Reconstruction of Core-Shell Dispersed Particles in Impact Polypropylene Copolymer during Extrusion

We reported an approach to reconstruct the complex phase morphology of impact polypropylene copolymer （IPC） with core-shell dispersed particles and to optimize its toughness in approximate shear condition. The molten-state annealing results indicate that the phase structure with core-shell dispersed particles is unstable and could be completely destroyed by static annealing, resulting in the degradation of impact strength. By using a co-rotating twin screw extruder, we found that the dispersed particle with core-shell structure could be rebuilt in appropriate condition with the recovery of excellent impact strength due to both the huge interfacial tension during solidification and the great difference in viscosity of components. Results reveal that almost all the extruded IPCs show the impact strength 60%-90% higher than that of annealed IPCs at room temperature. And the twice-extruded IPC shows the highest impact strength, 446% higher than that of IPC annealed for 30 min. As for low temperature tests, the impact strength of extruded IPCs also increases by 33%-58%. According to adjusting the processing conditions including extrusion speed, extrusion frequency and temperature, an optimization of toughness was well established.

Microstructure, morphology, crystallization and rheological behavior of impact polypropylene copolymer

Impact polypropylene copolymer (IPC), named polypropylene catalloy, not only possesses excellent impact property, but also presents good rigidity. Its superior performances result from the complicated composition and microstructure. In the present article, recent progress in the studies on microstructure, morphology, crystallization and rheological behavior of IPC is summarized, and findings of the authors and their collaborators are reported. In general, IPC is divided into three components, i.e., ethylene-propylene random copolymer (EPR), a series of different segment lengths ethylene-propylene copolymer (EbP) and propylene homopolymer. The reasonable macromolecular structures of EbP and a multilayered core-shell model of dispersed phase structure in IPC were proposed, in which the dispersed phase consists of an outer EbP shell, an inner EPR layer and an EbP core. It is found that the annealing at melt-state may lead to an abnormal phase inversion, and the phase inversion disappears when temperature cools down to room temperature. The cause of phase inversion is ascribed to the existence of EbP component, which results in the stronger activity of the dispersed phase. The crystalline structure and morphologic results confirm the formation of β-iPP in IPC. Furthermore, it is found that the ethylene content in IPC and cooling rate of the samples have an important influence on the formation of β-iPP. Based on the crystallization kinetics analyzed by Lauritzen-Hoffman theory, crystallization behavior of different IPC samples is discussed and it is proposed that the dilution effect of ethylene propylene copolymer has a more remarkable influence on surface nucleation than on crystal growth. In addition, annealing at high temperature can result in the changes of chain structure for IPC, and this instability is ascribed to the oxidative degradation and crosslink reaction mainly in iPP component.

Annealing Induced Microstructure and Mechanical Property Changes of Impact Resistant Polypropylene Copolymer

The effects of annealing on microstructure and mechanical properties of an impact resistant polypropylene copolymer （IPC） were investigated. Different annealing temperatures ranging from 80 ℃ to 160 ℃ were selected. The phase reorganization of IPC during annealing process was studied through morphological characterization technologies, including scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The crystalline structure changes in the IPC sample, including the iPP matrix and PE component, were investigated using wide angle X-ray diffraction （WAXD） and differential scanning calorimetry （DSC）. Dynamic mechanical analysis （DMA） was used to analyze the relaxation extent of 1PC before and after annealing. The results showed that annealing induced phase reorganization in IPC and the degree of phase reorganization depended on annealing temperature. The annealed IPC samples exhibited largely increased crystallinity compared with the unannealed one. Intensified damping peak with increased molecular chain mobility was achieved for the annealed IPC samples. At an appropriate annealing tem. perature （140 ℃）, largely enhanced impact strength was achieved for the annealed IPC sample. The toughening mechanisms were analyzed based on the phase reorganization and relaxation behavior.

椰壳纤维/IPC复合材料的应力-应变曲线拟合及界面改进

采用扫描电子显微镜、万能材料试验机对椰壳纤维/抗冲共聚聚丙烯(IPC)界面改进复合材料的断面形貌、力学性能进行了研究。利用高斯函数模型拟合椰壳纤维/IPC复合材料的应力-应变曲线,得到其数学表达式,计算曲线下的面积,得到各料的韧性模量。结果表明,马来酸酐接枝聚丙烯(MAH-g-PP)作为相容剂改性的复合材料各项力学性能均明显高于钛酸酯偶联剂的。而钛酸酯改性的复合材料又明显高于未界面改性的。扫描电镜(SEM)分析结果表明,MAH-g-PP改性的复合材料界面粘接明显好于钛酸酯的,这是复合材料力学性能提高的根本原因。

高熔体流动速率抗冲共聚聚丙烯的结构与性能研究

为提升高熔融抗冲共聚聚丙烯(IPC⁃J)的刚韧平衡性能,结合抗冲共聚聚丙烯(IPC⁃H)工艺,将IPC⁃J的乙烯含量和乙丙橡胶(EPR)中乙烯含量提高到了12.4%(质量分数,下同)和54%。对IPC⁃J、IPC⁃H、IPC⁃1和IPC⁃2等分别进行了分子链段结构和聚集态表征,结果显示,对比IPC⁃H的微观结构,IPC⁃J的EPR含量从19.4%增至22.8%,重均分子量(Mw)从2.0×10^(5)g/mol减至1.9×10^(5)g/mol,特性黏度(IV)从1.80 dL/g增到1.86 dL/g,分子量分布指数(MWD)从8.9增至10.7,EPR的最大分子量从1.1×10^(6)g/mol增至1.2×10^(6)g/mol;更多的、相对较长的长乙烯结晶链段有助于改善分散颗粒粒径,占比最大的粒径范围从0.3~0.6μm升至0.6~0.9μm;常温和低温冲击强度分别提升至11.0 kJ/m^(2)和5.7 kJ/m^(2)。以300 kt/年聚丙烯生产工艺为基础,在不改变齐格勒⁃纳塔(DQ)型催化剂体系的条件下,通过提高乙烯含量和EPR中乙烯含量实现了高熔融抗冲聚丙烯性能最大优化。

高韧性透明聚丙烯的制备及性能

本文研究不同牌号(PPB-MT25-S、SM198、J-570S、RP346R、UT8012M)聚丙烯(PP)的结晶行为、力学性能、低温韧性、透光率和雾度,同时考察了烯烃嵌段共聚物(OBC)、苯乙烯-丁二烯-苯乙烯嵌段共聚物(SEBS)、乙烯-辛烯共聚物(POE)、丙烯基弹性体(PBE)对牌号为PPB-MT25-S的PP(PP-B)性能的影响。结果表明,PP-B在128℃开始结晶,拉伸强度和常温(23℃)悬臂梁缺口冲击强度分别为23.9 MPa及12.6 kJ/m^(2),-5℃环境下悬臂梁缺口冲击强度为3.94 kJ/m^(2),透光率在80%以上,雾度为40.00%,PP-B表现出优异的综合性能。以PP-B为基体,分别采用OBC、SEBS、POE及PBE对其进行增韧。其中,SEBS增韧的PP材料(PP-B/SEBS)的拉伸强度和断裂伸长率分别为24 MPa及257%,常温下悬臂梁缺口冲击强度为16.4 kJ/m^(2),-5℃下悬臂梁缺口冲击强度为2.53 kJ/m^(2),表现出优异的力学性能及低温韧性。同时,PP-B/SEBS的刚韧平衡因子为1.76,表现出极高的刚韧平衡性;PP-B/SEBS的透光率和雾度分别为84.4%和23.87%,表现出优异的透光性。

热处理对IPC相形貌及性能的影响

研究了热处理的温度和时间对2种抗冲共聚聚丙烯(IPC)(EP533N-1,EP533N-2)分散相结构和力学性能的影响。结果表明:当热处理温度低于IPC熔融温度(167℃)时,橡胶相相对分子质量较小的EP533N-1分散相分布均匀性好于橡胶相相对分子质量较大的EP533N-2;当热处理温度高于167℃,EP533N-2分散相分布均匀性好于EP533N-1。热处理温度高于167℃时,EP533N-1中的乙烯丙烯嵌段共聚物(EbP)逐渐汇集成一个网络结构。2种IPC的常温抗冲击性能和弯曲模量均随热处理温度升高而增加,其中,热处理温度为100~130℃时,EP533N-1的低温抗冲击性能最佳,热处理温度为160℃时,EP533N-2的低温抗冲击性能最佳。

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。

长玄武岩纤维增强IPC复合材料的研究

以抗冲共聚聚丙烯(IPC)为基体,通过熔融浸渍工艺制备了长玄武岩纤维(LBF)增强IPC复合材料。研究了增容剂的种类、含量、LBF含量对复合材料力学性能的影响。结果表明,LBF的加入可以大幅度提高复合材料的拉伸、弯曲强度和硬度,而冲击强度明显降低。增容剂马来酸酐接枝共聚聚丙烯(PPB-g-MAH)对复合材料性能的改进效果明显好于马来酸酐接枝均聚聚丙烯(PPH-g-MAH)。通过扫描电子显微镜对断面形貌分析可知,LBF与纯IPC的相容性很差,但添加高含量增容剂后,BF与IPC的界面明显改善。PPH-g-MAH对复合材料的界面改进不明显,而PPB-g-MAH使复合材料的界面粘结性明显提高。实验证明,LBF增强IPC可以使复合材料的性能有较大提高,但增容剂用量明显高于玻纤增强IPC体系。

IPC K7116的工业化开发及其性能

在Horizone工艺装置上成功开发了中熔体流动速率(MFR)高橡胶含量抗冲共聚聚丙烯K7116,并表征了其结构,分析了其性能,讨论了不同因素对K7716力学性能的影响。结果表明:K7116的MFR为16g/10min,弯曲模量达1270MPa,冲击强度为12kJ/m^2;乙丙橡胶含量增加,使K7116的刚性降低,冲击强度增加;橡胶含量、乙丙橡胶部分与均聚聚丙烯部分的相对分子质量比,以及助剂选择对K7116的结晶性能和力学性能均有较大影响。

抗冲聚丙烯结构研究概述

介绍了近年来抗冲聚丙烯(HIPP)的多级结构(微观结构和介观结构)的研究进展,抗冲聚丙烯由均聚聚丙烯粒子和附着在聚丙烯粒子上形成的橡胶相组成,聚丙烯粒子由纳米级的初级粒子和微米级的次级粒子堆积,具有显著的多孔多尺度结构,橡胶相亦具有复杂的多组分“核-壳结构”。并从橡胶相的空间结构和及其结构尺寸两方面归纳总结了结构对抗冲聚丙烯抗冲性能的影响。

Unipol聚丙烯工艺抗冲共聚聚丙烯生产应用研究

介绍了Unipol气相流化床聚丙烯抗冲共聚聚丙烯生产情况,针对抗冲聚丙烯生产过程中物料单耗高、运行周期短、产品质量性能低等问题,在原有工艺操作的基础上对局部工艺流程及操作进行优化。实践表明,通过对第二反应器初始氮气压力、床重、乙烯加注速率控制,优化出料(PDS)系统控制,丙烯、乙烯物料损耗由1.007 t/tPP降低至1.003 t/tPP。新增给电子体注入装置可有效避免转移系统(IRTS)出料管线堵塞,结合工艺操作优化可增加运行周期。均聚物的本征黏度和橡胶分数的函数(β/α)、橡胶相含量(F_(C))指标协同控制可提高产品简支梁缺口冲击强度。添加成核剂能够有效提升产品性能。

抗冲共聚聚丙烯的结晶与相形态

用POM、DSC、WAXD、DMA、AFM对两种乙烯含量、相对分子量及其分布、橡胶相含量几乎完全相同的、韧性差异很大的抗冲共聚聚丙烯(IPC)的结晶、相形态进行了研究.实验结果表明,两者的结晶形态、结晶行为相似.相比IPC-B,IPC-A中分散相和基体的相容性较好.IPC基体、分散相的组成分析发现,分散相的外层为软的乙丙无规共聚物(EPR),内部为硬的聚乙烯(PE)晶区,构成一种复杂的包藏结构.IPC的增韧效果主要来自于相形态和分散状况的贡献.提出了IPC的相结构模型,以描述IPC多相体系的相结构及两种IPC中E-b-P的作用与差异.

抗冲共聚聚丙烯结构与性能

采用IR,GPC,SEM,DSC,DMA,拉伸和冲击实验机等对环管法制得的具有不同乙烯含量的四种抗冲共聚聚丙烯的结构和性能进行了研究。DMA曲线显示四种样品都存在两个Tg转变峰,表明样品中存在EPR相和非晶PP相;随着乙烯含量的增加,Izod冲击强度(23℃,-20℃)增加,而屈服强度、杨氏模量、弯曲强度、弯曲模量、热变形温度、脆化温度和洛氏硬度减小;用SEM观察到四种样品的EPR比较细且均匀地分散在基体中,橡胶粒子的平均粒径范围在0.48μm^0.61μm之间;DSC测得的四种样品的结晶度、ΔHm、ΔHc随乙烯含量的增加而减小。