几种不同结构型号PE改性PPR力学性能的研究

研究了线性低密度聚乙烯(LLDPE)/聚丙烯(PPR)共混体系、高密度聚乙烯(HDPE)/聚丙烯(PPR)共混体系、超高分子量聚乙烯(UHMWPE)/聚丙烯(PPR)共混体系的力学性能和熔体流动速率。结果表明,UHMWPE的增韧改性效果最好,在UHMWPE的含量为15%时体系的综合力学性能最好。LLDPE的增韧改性效果次之,HDPE的最差。     

BMDPE／LDPE／LLDPE共混熔体的流变行为与力学性能

研究了双峰中密度聚乙烯（BMDPE），低密度聚乙烯（LDPE）与线型低密度聚乙烯（LLDPE）共混熔体的流变行为和力学性能，讨论了共混物的组成，剪切应力和剪切速率以及温度对熔体流变行为，熔体粘度和膨胀比的影响，测定了不同配比熔体的非牛顿指数，熔体流动速率，粘流活性能及屈服应力，断裂应力和断裂伸长率，为BMDPE的加工和使用以及开发高性能价格比的PE材料提供了依据。     

茂金属聚乙烯与通用聚乙烯共混物熔体的流变行为研究

用茂金属线型低密度聚乙烯(mLLDPE)与通用聚乙烯(LDPE、LLDPE)进行共混,测定了共混物的熔体质量流动速率(MFR);研究了共混物熔体的熔体强度和剪切敏感性.结果发现:当质量分数超过20%的mLLDPE与高熔体质量流动速率(MFR)的通用聚乙烯共混时,或者质量分数小于40%的mLLDPE与低MFR的通用聚乙烯共混时,共混物熔体的流动性会小于单一共混组分,除了在与一种LDPE共混时mLLDPE加入质量分数为10%的一种共混物外,其他共混物的熔体强度都超过单个共混组分.mLLDPE/LLDPE共混物熔体的剪切敏感性高于LLDPE.     

PP／LDPE共混物熔体流动特性的研究

将两种熔融流动指数（ＭＦＩ）相差大的聚丙烯（ＰＰ）分别与一低密度聚乙烯（ＬＤＰＥ）进行共混，用熔体流动速率仪测定其流动特性。发现ＭＦＩ值高的ＰＰ，当共混比ＰＰ／ＬＤＰＥ为５０／５０时，其熔体流动速率（ＭＦＲ）为最大，本文对此作了初步的分析和讨论。     

茂金属聚乙烯（mPE）／高压聚乙烯（LDPE）共混熔体的流变学

研究了不同比例共混的茂金属聚乙烯（mPE)和高压聚乙烯（LDPE）熔体的流变行为,讨论了共混物组成、剪切速率和剪切应力以及温度对熔体流变曲线、熔体粘度和膨胀比的影响,mPE的加工提供了理论依据。不同共混比的熔体均为假塑性流体,且熔体假塑性随LDPE含量增大而增强。熔体流动活化能随LDPE组成的增加逐渐增大,粘度对温度的敏感性增强,共混物的非牛顿指数随LDPE的增加而降低,改善了mPE的加工性能。     

mPE弹性体/PP共混物的流变行为与力学性能

用茂金属聚乙烯弹性体（mPE)代替传统的弹性体,对聚丙烯（PP）进行增韧改性,绘制了不同配比mPE/PP共混物熔体的流变曲线,讨论了共混物的组成,切应力和剪切速率以及温度对熔体流变行为,熔体粘度的影响。测定了共混物熔全的非牛顿指数,熔体质量流动速率及力学性能,为mPE共混改性PP提供了理论依据。结果表明,mPE适用于PP的增韧改性,增韧效果取决于共混物中mPE的用量,当mPE质量分数达到25%-40%时,共混材料既有较高的拉伸强度和韧性,又有较好的加工性能,mPE/PP共混物熔体的假塑性流动随mPE用量的增加向更高切应力或更高剪切速率方向移动。     

聚乙烯/聚丙烯共混体系力学性能的研究

研究了线型低密度聚乙烯（LLDPE）／聚丙烯（PP）共混体系、高密度聚乙烯（HDPE）／PP共混体系、超高相对分子质量聚乙烯（UHMWPE）／PP共混体系的力学性能和熔体流动速率。结果表明，UHMWPE的增韧效果最好，在UHMWPE的质量分数为15％时体系的综合力学性能优异，当UHMWPE质量分数大于15％时，材料的综合性能开始下降。     

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一种高稳定性大孔径有序介孔碳材料及其制备方法,一种无卤膨胀型阻燃材料及其制备方法,一种低光泽度聚丙烯共混改性材料及其制备方法,一种高熔体强度聚丙烯树脂及其制备方法,四层复合金属增强聚乙烯管材.     

PP/PE熔体流动速率比与共混体系力学性能的关系

选择不同熔体流动速率(MFR)的乙-丙共聚型聚丙烯(PP)和聚乙烯(PE),分别配混出一系列不同熔体流动速率比(R_M=MFR_(PP)/MFR_(PE))的共混体系。深入探讨了共聚PP/PE共混体系的力学性能与PP和PE间R_M的关系。结果表明,在适宜的R_M范围內,PE能对乙-丙共聚型PP具有良好增韧增强效果。在025后,体系性能劣化。     

废胶粉/聚丙烯接枝物共混材料的制备与性能

采用熔融接枝法分别制备了高强度和高熔体流动速率的聚丙烯接枝马来酸酐共聚物,以改善聚丙烯与胶粉间的界面相容性,提高废胶粉/聚丙烯接枝物共混材料的力学性能和流动性.力学性能测试结果表明,随着废胶粉用量的增加,废胶粉/聚丙烯接枝物共混材料的拉伸性能下降,扯断伸长率和缺口冲击强度均增大,熔体流动速率减小,流动性变差.由热重分析...     

Mechanical properties and morphology of crosslinked PP/PE blends and PP/PE/propylene–ethylene copolymer blends

Blending is an effective method for improving polymer properties. However, the problem of phase separation often occurs due to incompatibility of homopolymers, which deteriorates the physical properties of polyblends. In this study, isotactic polypropylene was blended with low-density polyethylene. Crosslinking agent and copolymers of propylene and ethylene (either random copolymer or block copolymer) were added to improve the interfacial adhesion of PP/LDPE blends. The tensile strength, heat deflection temperature, and impact strength of these modified PP/PE blends were investigated. The microstructures of polyblends have been studied to interpret the mechanical behavior through dynamic viscoelasticity, wide-angle X-ray diffraction, differential scanning calorimetry, picnometry, and scanning electron microscopy. The properties of crosslinked PP/PE blends were determined by the content of crosslinking agent and processing method. For the material blended by roll, a 2% concentration of peroxide corresponded to a maximum tensile strength and minimum impact strength. However, the mechanical strength of those products blended by extrusion monotonously decreased with increasing peroxide content because of serious degradation. The interfacial adhesion of PP/PE blends could be enhanced by adding random or block copolymer of propylene and ethylene, and the impact strength as well as ductility were greatly improved. Experimental data showed that the impact strength of PP/LDPE/random copolymer ternary blend could reach as high as 33.3 kg · cm/cm; however, its rigidity and tensile strength were inferior to those of PP/LDPE/block copolymer blend.     

相容剂改性PE/PP共混物在滴灌带中的应用

介绍了相容剂改性聚乙烯/聚丙(烯PE/PP)共混物在生产滴灌带中的应用,探讨了相容剂改性PE/PP共混体系的相容机理,通过大量的实验找到了最佳配比方案。结果表明:以相容剂改性PE/PP共混物生产的滴灌带与普通滴灌带对比界面黏结性强;改善和提高了PE/PP共混物的相容性和力学性能。     

Miscibility and crystallization of metallocene polyethylene blends with polypropylene

The crystallization and morphology of very‐low‐density polyethylene (VLDPE) and ultra‐low‐density polyethylene (ULDPE) blends with isotactic polypropylene (PP) were studied by differential scanning calorimetry (DSC) and hot‐stage optical microscopy (HSOM) with polarized light. In particular, the isothermal crystallization of PP in molten PE was investigated. A polypropylene homopolymer was melt‐blended with six types of VLDPEs and ULDPEs, with variations in branch content and length and in molecular weight. All the blends contained 20% PP by mass. It was found that the crystallization temperatures of PP and PE changed in the blends, and the crystallization of PP was affected by branch length and content and by the molecular weight of the PE, indicating a certain degree of miscibility between PP and PE. The isothermal crystallization rate of PP decreased in the blends; in particular, the crystallization rate of PP was slower in the ULDPE with lower MFI, suggesting that crystallization of PP was hindered by PE and that its rate was regulated by the viscosity of ULDPE. HSOM images showed that a portion of the PP crystallized from molten PE, although phase separation was obvious, providing additional information on the miscible behavior between PP and VLDPEs (or ULDPEs). Furthermore, the miscible level between the PP and the ULDPEs was higher than that between the PP and the VLDPEs because the degree of change in the crystallization behavior of the PP and PE was greater in the PP–ULDPE blends. This was possibly a result of the higher branch content in the ULDPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1179–1189, 2003     

废旧聚丙烯编织袋回收料改性应用研究

废旧聚丙烯(PP)编织袋回收料分别与回收聚乙烯(PE)、回收橡胶粉、木粉共混,制备了增韧PP材料、热塑性弹性体和木塑复合材料,采用力学性能测试、SEM和DSC分析等手段对其性能和结构进行了表征。结果表明:随着回收聚乙烯(PE)含量的增加,回收PP/PE共混物的拉伸强度和冲击强度迅速提高;回收PP/橡胶粉共混物中加入聚丙烯接枝马来酸酐(PP-g-MAH)能起到增容的效果,随PP-g-MAH含量的增加,共混物的拉伸强度上升,永久变形减小;在回收PP/木粉复合材料中加入PP-g-MAH后,复合材料的冲击强度明显提高。     

Study on morphology of ternary polymer blends. II. Effect of composition

The composition effect on morphology of polypropylene/ethylene–propylene–diene terpolymer/polyethylene (PP/EPDM/PE) and polypropylene/ethylene–propylene–diene terpolymer/polystyrene (PP/EPDM/PS) ternary blends has been investigated. In all of the blends, polypropylene as the major phase was blended with two minor phases, that is, EPDM and PE or PS. From morphological studies using the SEM technique a core–shell morphology for PP/EPDM/PE and separated dispersed morphology for PP/EPDM/PS were observed. These results were found to be in agreement with the theoretical predictions. The composition of components affected only the size of dispersed phases and had no appreciable effect on the type of morphology. The size of each dispersed phase, whether it forms core or shell or disperses separately in matrix, can be related directly to its composition in the blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1138–1146, 2001     

On the mechanism of compatibilization of polyolefin/liquid crystalline polymer blends with graft copolymers

The compatibilization mechanism of some compatibilizers for blends of polyolefins with a liquid crystalline polymer (LCP) was studied. Polyethylene (PE) and polypropylene (PP) were blended with a semirigid LCP (SBH) in a batch mixer, either with and without compatibilizers. The latter were two commercially available samples of functionalized polyolefins, that is, a PE‐g‐MA (HDM) and a PP‐g‐AA (Polybond 1001) copolymer and some purposely synthesized PE‐g‐LCP and PP‐g‐LCP copolymers. Microtomed films of the binary and the ternary blends were annealed at 240°C on the hot stage of a polarizing microscope and the changes undergone by their morphology were recorded as a function of time. The results indicate that the compatibilizers lower the interfacial tension, thereby providing an improvement of the minor phase dispersion. In addition to this, the rate of the coalescence caused by the high‐temperature treatment is appreciably reduced in the systems compatibilized with the PE–SBH and PP–SBH graft copolymers. Among the commercial compatibilizers, only Polybond 1001 displayed an effect comparable to that of the above copolymers. HDM improved the morphology of the as‐prepared PE blends, but failed to grant sufficient morphological stabilization against annealing‐induced coarsening. The results are discussed with reference to the chemical structure of the different compatibilizers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3027–3034, 2000     

Evaluation of olefinic block copolymer blends with amorphous polyolefins—effect of different unsaturated and saturated hydrocarbon tackifier resins on blend miscibility

Blends of ethylene–octene based olefinic block copolymer (OBC) with two amorphous polyolefin (APO) polymers [atactic propylene homopolymer (PP) and ethylene–propylene copolymer (PE–PP)] were evaluated at three different ratios. Dynamic mechanical analysis (DMA) and transmission electron microscopy (TEM) evaluations were performed to determine the blend miscibility characteristics. Viscoelastic properties of both OBC blends with PP polymer, and OBC blends with PE–PP copolymer showed incompatibility. Analysis revealed that both blends formed two phase morphologies. The effect of three unsaturated aliphatic hydrocarbon resins with varying aromatic content and two saturated hydrocarbon resins with different chemistries were evaluated as compatibilizing agent for OBC/PP and OBC/PE–PP blends. A 1 : 1 polymer blend ratio of OBC/PP and OBC/PE–PP was selected to better understand the influence of resin addition at three different levels 20, 30, and 40 wt %. The fully aliphatic unsaturated resin seems to improve the miscibility of the OBC/PP blends at higher resin addition levels, but reduced the miscibility as the aromatic content of the resin increases. However, OBC/PE–PP blends showed improved miscibility with increasing aromatic content. A ternary phase morphology was particularly observed for both OBC/PP and OBC/PE–PP blends with highly aromatic (14%) unsaturated hydrocarbon resin, in which OBC formed the continuous phase, and PP, PE–PP, and unsaturated hydrocarbon resins formed the dispersed phase. Interestingly, we did not observe much difference in miscibility characteristics between the two saturated resin chemistries in both blend systems (OBC/PP and OBC/PE–PP). The Harkins spreading coefficient concept was used to better understand the ternary blend dispersed phase morphology. Spreading coefficients indicate that the free hydrocarbon resins (both unsaturated and saturated) were encapsulated by the amorphous PP or amorphous PE–PP polymer in the dispersed phase for the respective blend compositions. Overall OBC–PP and OBC/PE–PP blends showed better miscibility characteristics with both saturated aliphatic hydrocarbon resins, irrespective of the difference in resin chemistries. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2624–2644, 2013     

Mechanical properties and morphology of polyethylene–polypropylene blends with controlled thermal history

The effect of time–temperature treatment on the mechanical properties and morphology of polyethylene–polypropylene (PE–PP) blends was studied to establish a relationship among the thermal treatment, morphology, and mechanical properties. The experimental techniques used were polarized optical microscopy with hot‐stage, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and tensile testing. A PP homopolymer was used to blend with various PEs, including high‐density polyethylene (HDPE), low‐density polyethylene (LDPE), linear low‐density polyethylene (LLDPE), and very low density polyethylene (VLDPE). All the blends were made at a ratio of PE:PP = 80:20. Thermal treatment was carried out at temperatures between the crystallization temperatures of PP and PEs to allow PP to crystallize first from the blends. A very diffuse PP spherulite morphology in the PE matrix was formed in partially miscible blends of LLDPE–PP even though PP was present at only 20% by mass. Droplet‐matrix structures were developed in other blends with PP as dispersed domains in a continuous PE matrix. The SEM images displayed a fibrillar structure of PP spherulite in the LLDPE–PP blends and large droplets of PP in the HDPE–PP blend. The DSC results showed that the crystallinity of PP was increased in thermally treated samples. This special time–temperature treatment improved tensile properties for all PE–PP blends by improving the adhesion between PP and PE and increasing the overall crystallinity. In particular, in the LLDPE–PP blends, tensile properties were improved enormously because of a greater increase in the interfacial adhesion induced by the diffuse spherulite and fibrillar structure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1151–1164, 2000     

Processing of polyolefin blends

The morphology of binary and ternary polyolefin blends of polypropylene (PP), ethylene-propylene-diene terpolymer (EPDM) and polyethylene (PE) following processing by injection and compression molding has been examined by optical and scanning electron microscopy. Internal surfaces were generated by low temperature fracture and etching with cyclohexane. In binary blends, droplets of EPDM are elongated in the flow direction within 400μm of the mold surface in injection molding, yielding a skin region which is distinct from an isotropic core containing spherical EPDM inclusions. Spherical droplets of EPDM or PE in binary blends with PP increase in size with increasing compression molding time. In ternary blends, spherical inclusions containing both EPDM and PE are dispersed in PP. With increasing compression molding time, EPDM separates from PE and concentrates at the outer edges of the PE inclusion, effectively isolating PE from the PP matrix.     

Tensile properties and morphology of blends of polyethylene and polypropylene

The tensile behavior of blends of linear polyethylene (PE) and isotactic polypropylene (PP) was examined in relation to their morphology. Yield stress increases monotonically with increasing PP content, while true ultimate strength is much lower in all blends than in the pure polymers as a result of early fracture. The blends fail at low elongation because of their two-phase structure, consisting of interpenetrating networks or of islands of PE in a PP matrix, as shown by scanning electron microscopy of fracture surfaces and transmission electron microscopy of thin films. While spherulites in PP are very large (～100 μm in diameter), addition of 10% or more of PE drastically reduces their average size. This, together with the profusion of intercrystalline links introduced by PE, may be associated with maximization of tensile modulus in blends containing ～80% PP. Introduction of special nucleating agents to PP reduces average spherulite size and is accompanied by slight improvements in modulus. Thin films of blends strained in the electron microscope neck and fibrillate in their PE regions, but fracture cleanly with little fibrillation in areas of PP.