共聚聚丙烯（cPP）／线型低密度聚乙烯（UDPE）共混体系的流变与结晶形为

用毛细管流变仪研究了共聚聚丙烯(cPP)与线型低密度聚乙烯(LLDPE)共混物熔体的流变行为。讨论了共混物的组成、切应力和剪切速率对熔体流变行为和熔体粘度的影响。测定了不同配比共混物熔体的非牛顿指数。结果表明：共混物熔体属假塑性流体，但共混体系粘度随LLDPE加入量的增加变化不大。DSC结晶曲线及扫描电镜(SEM)照片表明，LLDPE的加入使CPP的结晶温度变化不大，但对晶体形态有一定影响。LLDPE对CPP有一定的增韧改性作用，当LLDPE质量分数为15％时，共混物的冲击强度增幅在40％左右，而拉伸强度保持率为80％。     

共聚聚丙烯／茂金属线形低密度聚乙烯共混体系的流变行为与结晶行为

用毛细管流变仪研究了冲击性能相对优良的共聚聚丙烯(cPP)与茂金属低密度聚乙烯(m-PE—LLD)共混物熔体的流变行为。讨论了共混物的组成、剪切应力和剪切速率对熔体流变行为、熔体粘度的影响。测定了不同cPP及m—PE—LLD配比的共混物熔体的非牛顿指数。结果表明：共混物熔体属假塑性流体，但其粘度随m—PE—LLD加入量的增加变化不大。DSC分析及微观形态分析表明，m-PE—LLD的加入使cPP的结晶温度提高，具有异相成核作用。m-PE—LLD对cPP有明显的增韧作用，当m—PE—LLD含量为15％时，共混物的冲击强度明显提高，增幅在75％左右，而拉伸强度保持率为85％以上。     

茂金属聚乙烯(MPE)/线性低密度聚乙烯(LLDPE)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)和线性低密度聚乙烯 (LLDPE)熔体的流变学行为 ,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、熔体粘度的影响 ,为MPE的共混改性提供了理论依据。结果表明 :随着LLDPE含量的增加 ,共混熔体的粘度降低 ,转变应力和非牛顿指数减小 ,粘流活化能升高 ,MPE的流动性和加工性能得到改善。     

聚丙烯／无规共聚聚丙烯共混物的流变行为与力学性能研究

以毛细管流变仪研究了聚丙烯(PP)／无规共聚聚丙烯(PP-R)共混物熔体的流变行为。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、熔体粘度的影响。测定了不同配比共混物熔体的非牛顿指数和膨胀比。结果表明：PP／PP-R共混物熔体属假塑性流体，其熔体粘度随PP-R含量的增加而迅速增大。力学性能测试结果表明，PP-R对PP有很好的增韧改性作用。另外，也用偏光显微镜研究了PP-R对共混物结晶形态的影响。     

HDPE／LLDPE共混物力学及流变行为的研究

以国产HDPE和LLDPE为原料,对不同体系配比的机械共混物的拉伸力学行为、熔体指数(MI)、转矩流变行为、DSC行为等进行了系统的研究,发现体系的拉伸强度与LLDPE含量呈负向协同效应;MI值随着LLDPE含量增加而近似线性增大,LLDPE的加入能有效地改善加工性能、降低能耗;DSC分析表明体系发生共结晶。对HDPE/LLDPE/CPE三元体系的MI变化和热行为的研究发现,CPE10％时能有效地增进体系的相容性,改善体系的结晶性能。     

PTT/PP共混物的性能研究

通过熔融共混制备了聚对苯二甲酸丙二酯/聚丙烯(PTT/PP=75/25)及其马来酸酐接枝PP(PP-g-MAH)增容共混物,研究了PTT/PP及其增容共混物的结晶性能、力学性能、流变性能和结晶形态。研究结果表明,PTT与PP共混能提高PP、PTT组分的结晶温度;对于增容共混物,随PP-g-MAH用量的增加,PP和PTT的结晶温度基本不变。加入PP使PTT拉伸强度降低,冲击强度提高;PP-g-MAH增容使共混物的拉伸和冲击强度都提高。增容共混物的熔体粘度明显降低,存在明显的剪切变稀现象,但熔体粘度与PP-g-MAH用量无关。在一定用量范围内,随PP-g-MAH用量的增加,PP分散相的尺寸变小。     

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.     

振动共混转矩流变仪及其应用

介绍了振动共混转矩流变仪.该仪器既可以进行稳态共混研究,也可以进行振动共混对聚合物流变性能或者物理过程(如相态和结晶及熔融)影响的研究.所建立的流变模型可以分析聚合物共混物熔体粘度相对高低;应用Lee等分析稳态共混过程共混物相形态演变的方法基本适应振动共混过程,但必须注意振动流场的特点;振动共混过程可以影响制备10/90 UHMWPE/PP结晶的晶体类型和熔融行为.     

LLDPE-g-GMA增容LLDPE/PET共混物的研究

采用熔融挤出法制备了线型低密度聚乙烯接枝甲基丙烯酸缩水甘油酯(LLDPE-g-GMA)反应增容LLDPE/聚对苯二甲酸乙二醇酯(PET)共混物,用拉力试验机、差示扫描量热仪(DSC)和毛细管流变仪研究了LLDPE-g-GMA对共混物的力学性能、结晶性能及流变性能的影响。结果表明,LLDPE-g-GMA有效地提高了LLDPE/PET共混物的拉伸和冲击性能,同时也提高了LLDPE的结晶速率;流变性能测试证明LLDPE-g-GMA提高了共混物熔体的表现黏度,表明LLDPE-g-GMA有效地改善了不相容共混物两相之间的相容性。     

热塑性聚酯弹性体共混改性线性低密度聚乙烯

采用熔融共混法制备了线性低密度聚乙烯(LLDPE)/热塑性聚酯弹性体(TPEE)共混物,借助电子万能材料试验机、差示扫描量热仪等手段,研究了共混物的结晶行为和力学性能。结果表明,少量TPEE对LLDPE结晶的完善性有一定影响,LLDPE的结晶度稍有减小,断裂伸长率和拉伸强度均有提高。随着TPEE用量的增加,LLDPE的断裂伸长率和拉伸强度先升高后降低,当TPEE的质量分数在2%~3.5%时,分别有最大值851.1%和18.758MPa。     

Melt rheology and morphology of LLDPE/EVA blends: Effect of blend ratio,compatibilization, and dynamic crosslinking

The melt rheological properties of linear low‐density polyethylene (LLDPE)/ethylene vinyl acetate (EVA) blends were investigated with special reference to the effect of blend ratio, temperature, shear rate, compatibilization, and dynamic vulcanization. The melt viscosity of the blends determined with a capillary rheometer is found to decrease with an increase of shear rate, which is an indication of pseudoplastic behavior. The viscosity of the blend was found to be a nonadditive function of the viscosities of the component polymers. A negative deviation was observed because of the interlayer slip between the polar EVA and the nonpolar LLDPE phases. The melt viscosity of these blends decreases with the increased concentration of EVA. The morphology of the extrudate of the blends at different shear rates and blend ratios was studied and the size and distribution of the domains were examined by scanning electron microscopy. The morphology was found to depend on shear rate and blend ratio. Compatibilization of the blends with phenolic‐ and maleic‐modified LLDPE increased the melt viscosity at lower wt % of compatibilizer and then leveled off. Dynamic vulcanization is found to increase the melt viscosity at a lower concentration of DCP. The effect of temperature on melt viscosity of the blends was also studied. Finally, attempts were made to correlate the experimental data on melt viscosity and cocontinuity region with different theoretical models. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3210–3225, 2002     

Rheology and morphology study of immiscible linear low‐density polyethylene/poly(lactic acid) blends filled with nanosilica particles

The objectives of this study are to investigate the effect of silica nanoparticles on the morphology and rheological behavior of immiscible linear low‐density polyethylene/poly(lactic acid) (LLDPE/PLA) blends. Melt blending method is applied to prepare the blends and their nanocomposites. Scanning electron microscope and parallel plate rheometer were used to investigate morphology and rheological behavior of the blend nanocomposites. Scanning electron microscope results demonstrated a significant change in morphology behavior by incorporation of silica nanoparticles. A significant reduction in the PLA droplet for LLDPE/PLA (75/25) with 8 wt % silica was observed. The rheological studies illustrated that for all samples storage modulus and complex viscosity of blend nanocomposites are higher than neat blends. Finally, melt rigidity of blend nanocomposites was estimated by measurement of rheological properties using a rotational rheometer through small amplitude oscillatory shear experiments. As a result, through the shear data, a high value quantity as a criteria for melt rigidity is obtained for the LLDPE/PLA (75/25) with 8 wt % silica in comparing to the other samples. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45526.     

海泡石/UHMWPE/LLDPE复合材料动态流变学行为研究

利用偏光显微镜(POM)和高级流变扩展系统仪(ARES)对海泡石/超高分子量聚乙烯(UHMWPE)/线性低密度聚乙烯(LLDPE)复合材料的流变学行为进行了研究。结果表明,改性后的海泡石表现出不同的流变学行为,用KH-550改性效果较好;UHMWPE颗粒在不同的温度下具有不同的形态,随着转矩流变仪混炼温度的提高,复合体系熔体黏弹性参数发生改变,其中低频储能模量(G’)和零切黏度(η0)逐渐升高,损耗因子(tanδ)在低频区出现内耗峰,表明加工条件的改变引起了熔体结构的转变,从而改变了动态流变学性能。     

Microcellular foaming of PE/PP blends

Three different polyethylene/polypropylene (PE/PP) blends were microcellular foamed and their crystallinities and melt strengths were investigated. The relationship between crystallinity, melt strength, and cellular structure was studied. Experimental results showed that the three blends had similar variation patterns in respect of crystallinity, melt strength, and cellular structure, and these variation patterns were correlative for each blend. For all blends, the melt strength and PP melting point initially heightened and then lowered, the PP crystallinity first decreased, and then increased as the PE content increased. At PE content of 30%, the melt strength and PP melting point were highest and the PP crystallinity was least. The blend with lower PP crystallinity and higher melt strength had better cellular structure and broader microcellular foaming temperature range. So, three blends had best cellular structure at PE content of 30%. Furthermore, when compared with PE/homopolymer (hPP) blend, the PE/copolymer PP (cPP) blend had higher melt strength, better cellular structure, and wider microcellular foaming temperature range, so it was more suited to be microcellular foamed. Whereas LDPE/cPP blend had the broadest microcellular foaming temperature range because of its highest melt strength within three blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4149–4159, 2007     

茂金属聚乙烯蜡对PE共混体系流变行为的影响

用毛细管流变仪研究了茂金属聚乙烯蜡改性聚乙烯共混体系的流变行为，探讨了茂金属聚乙烯蜡用量对共混体系熔体流变行为、熔体黏度、非牛顿指数和流动活化能的影响。结果表明：茂金属聚乙烯蜡对LLDPE／LDPE流动黏度降低明显，增加用量可使黏度逐渐降低；而对MPE／LLDPE／LDPE共混体系流动行为的影响比较复杂，在低剪切应力下黏度随茂金属聚乙烯蜡用量增加而逐渐降低，而在高剪切应力下黏度先增后减；茂金属聚乙烯蜡与MPE／LLDPE／LPDPE的相容性好于LLDPE／LDPE共混体系。     

Modification of recycled high‐density polyethylene by low‐density and linear‐low‐density polyethylenes

The present study investigated mixed polyolefin compositions with the major component being a post‐consumer, milk bottle grade high‐density polyethylene (HDPE) for use in large‐scale injection moldings. Both rheological and mechanical properties of the developed blends are benchmarked against those shown by a currently used HDPE injection molding grade, in order to find a potential composition for its replacement. Possibility of such replacement via modification of recycled high‐density polyethylene (reHDPE) by low‐density polyethylene (LDPE) and linear‐low‐density polyethylene (LLDPE) is discussed. Overall, mechanical and rheological data showed that LDPE is a better modifier for reHDPE than LLDPE. Mechanical properties of reHDPE/LLDPE blends were lower than additive, thus demonstrating the lack of compatibility between the blend components in the solid state. Mechanical properties of reHDPE/LDPE blends were either equal to or higher than calculated from linear additivity. Capillary rheological measurements showed that values of apparent viscosity for LLDPE blends were very similar to those of the more viscous parent in the blend, whereas apparent viscosities of reHDPE/LDPE blends depended neither on concentration nor on type (viscosity) of LDPE. Further rheological and thermal studies on reHDPE/LDPE blends indicated that the blend constituents were partially miscible in the melt and cocrystallized in the solid state.     

Flow behavior of LDPE and its blends with LLDPE I and II: A comparative study

Studies on melt rheological properties of blends of low density polythylene (LDPE) with selected grades of linear low density polyethylene (LLDPE), which differ widely in their melt flow indices, are reported. The data obtained in a capillary rheometer are presented to describe the effects of blend composition and shear rate on flow behavior index, melt viscosity, and melt elasticity. In general, blending of LLDPE I that has a low melt flow index (2 _g/10 min) with LDPE results in a decrease of its melt viscosity, processing temperature, and the tendency of extrudate distortion, depending on blending ratio. A blending ratio around 20–30% LLDPE I seems optimum from the point of view of desirable improvement in processability behavior. On the other hand, blending of LLDPE II that has a high melt flow index (10_g/10 min) with LDPE offers a distinct advantage in increasing the pseudoplasticity of LDPE/LLDPE II blends. © 1996 John Wiley & Sons, Inc.     

Dynamic rheological,morphology and mechanical properties of compatibilized LLDPE/EMA blends

Blends of linear low density polyethylene (LLDPE) and ethylene-co-methyl acrylate (EMA) having 60/40 composition was studied with and without compatibilizing agent. The compatibilizing agent used was maleic anhydride grafted linear low density polyethylene (LLDPE-g-MA). The LLDPE backbones of the compatibilizer are compatible with LLDPE blend component, whereas the maleic anhydride is affinated with carbonyl groups of EMA. The effectiveness of the compatibilizing agent was evaluated using different techniques like mechanical, thermal, scanning electron microscopy and rheological studies. Best compatibilization effect was found in the blend at a loading of 3 wt% of compatibilizer since at this level of compatibilizer complex viscosity, tensile strength, modulus, elongation at break, impact strength was found to be higher. The increase in the melt viscosity, storage modulus and thermal stability of the compatibilized blends indicated enhanced interactions between the discrete LLDPE and EMA phases induced by the functional compatibilizer.     

凝胶丁腈共聚弹性体增韧聚甲醛的加工流变行为及力学性能

研究了聚甲醛(POM)/凝胶丁腈共聚弹性体(GNBE)共混物的熔体流动指数(MFI)、高压毛细管流变行为和力学性能。结果表明,共混物MFI随GNBE用量的增加下降较大。聚酰胺(PA)对POM/GNBE共混体系的MFI影响较小,而热塑性酚醛树脂(PFR)的影响显著。当PFR的质量份为4时,POM共混物的MFI达最小值(0.053g/min),约为未加增容剂POM共混物MFI的1/6。随着剪切速率的提高,共混物剪切黏度迅速与POM接近。这种黏度变化行为说明共混物比GNBE对剪切速率更敏感,共混物的黏度受POM的影响较大。随着剪切速率的提高,POM与GNBE的黏度比迅速减小,并接近1,说明POM和GNBE在高剪切速率下共混时,GNBE的液滴能够在POM连续相中分散达到最小。含20份GNBE的POM共混物在高剪切速率下的熔体表观黏度与POM相当;在PFR质量份为6时,POM共混物的缺口冲击强度达到21.6kJ/m2,超过了GNBE质量份为40的POM共混物。当PFR质量份为4时,共混物的缺口冲击强度为对应的不加增容剂共混物的冲击强度的2倍多,扯断伸长率提高了55.4%。