MiniLab表征共混高聚物熔体相容性方法的探讨

利用MiniLab微型混合流变仪测定的高聚物熔体平衡转矩-转速关系曲线探讨表征共混高聚物熔体相容性的方法,研究高密度聚乙烯(HDPE)和聚丙烯(PP)共混物熔体的相容性.结果表明:HDPE/PP共混物熔体是完全互容的.     

相容共混物熔体的平衡转矩与组成关系的探讨

以熔体指数不同的高密度聚乙烯(HDPE)和均聚聚丙烯(PP)为试样,利用MiniLab微型混合流变仪,研究了在熔融状态下完全互容的HDPE/HDPE、PP/PP和HDPE/PP共混物熔体的平衡转矩随组成的变化规律。结果表明:相容共混体系的熔体平衡转矩-组成关系曲线一般表现为线性或者二次抛物曲线。当高分子链的化学结构单元不同时,其共混熔体的平衡转矩-组成关系多为二次抛物曲线。     

ABS/PC共混物的转矩及毛细管流变行为

采用转矩流变仪和毛细管流变仪研究了丙烯腈-丁二烯-苯乙烯(ABS)/聚碳酸酯(PC)共混体系的流变行为,研究共混物组成对熔体流变行为的影响.结果表明:转矩流变仪中,平衡温度随着转速提高而增大,平衡转矩会在某一转速下达到峰值.两种测试方法得到的流变数据基本一致,共混物熔体呈现剪切变稀的假塑性流体特性.随着PC含量的增加,共混物的表现黏度逐渐增大,共混物熔体的非牛顿指数表现为负偏差,黏流活化能则表现出正负偏差,说明ABS与PC间具有一定的相容性.     

不相容共混高聚物熔体的平衡转矩-组成关系

选用苯乙烯-丙烯腈共聚物(SAN),高密度聚乙烯(HDPE),聚丙烯(PP)和线性低密度聚乙烯(LLDPE)为样品,利用MiniLab微型混合流变仪,研究了SAN/HDPE,SAN/PP和SAN/LLDPE共混高聚物熔体不相容体系的平衡转矩随组成变化的规律。结果表明:与相容共混体系不同,不相容共混体系的平衡转矩不随组成单调的递增或递减,而呈现水平钝角型或者U型曲线变化。当两纯组分的流动性差异较大时其为水平钝角型曲线,相近时则为U型曲线。     

超高分子量聚乙烯/高密度聚乙烯共混物的低温冲击研究

通过DSC、SEM和动态流变法分析超高分子量聚乙烯/高密度聚乙烯(UHMWPE/HDPE)共混物的相容性。结果表明:UHMWPE和HDPE具有良好的相容性。UHMWPE/HDPE共混物是典型的假塑性流体,当HDPE的质量分数逐渐增大,共混物的复数黏度明显减小,其流动性变好。UHMWPE能够显著提高共混物的低温冲击性能,当UHMWPE含量超过40%,共混物在-60℃的缺口冲击强度在70 kJ/m²以上。当UHMWPE含量为50%,共混物的熔体流动速率为0.12 g/10min,-60℃缺口冲击强度达到77 kJ/m²,使加工性和低温冲击性能达到平衡。     

同向双螺杆熔体输送段捏合盘错列角对不相容体系共混物相态结构的影响

对啮合同向双螺杆挤出机,将捏合盘置于熔体输送段,通过改变捏合盘错列角,研究双螺杆挤出过程熔体输送段捏合盘错列角对不相容体系共混物相态结构的影响。应用差示扫描量热仪对两相共混体系HDPE/PS的热性能进行了实验研究,结果表明:螺杆构型对共混物的相容性影响不大。同时采用扫描电子显微镜考察了HDPE/PS共混物在熔体输送段末端位置和机头末端所取试样的相态结构,研究表明:置于熔体输送段捏合盘元件错列角对共混物分散相的相畴尺寸有一定影响。     

SEBS/HDPE共混物加工性能及力学性能的研究

以苯乙烯-乙烯-丁二烯-苯乙烯嵌段共聚物（SEBS）／高密度聚乙烯（HDPE）为共混改性的研究对象，采用哈克转矩流变仪进行共混，讨论了不同用量、不同类型的HDPE对共混物加工流变性能、冲击性能和拉伸性能的影响。结果表明，当添加的HDPE份数达到20phr时，能显著提高共混物的冲击性能和拉伸性能，同时共混物的加工流变性能也有了很大的改善。因此质量比为100／20的SEBS／HDPE体系是一个比较理想的共混体系。     

HDPE/sPS共混体系结构与性能的研究

用2种分子量不同的苯乙烯-(乙烯/丁烯)-苯乙烯三嵌段共聚物(SEBS)和一种苯乙烯-b-乙烯/丁烯(SEB)两嵌段共聚物为增容剂,对高密度聚乙烯(HDPE)/间规聚苯乙烯(sPS)共混物进行增容.采用扫描电镜(SEM)及拉伸试验研究了增溶剂的分子量及结构对共混物形态结构及力学性能的影响.结果表明:3种增容剂SEBS(SEB)均可有效地降低sPS分散相的尺寸并增加HDPE/sPS共混物的界面强度,从而提高其力学性能.sPS 的掺入可以显著提高HDPE的耐热性能.     

HDPE/sPS增容共混复合材料的研究

用2种分子量不同的苯乙烯-(乙烯/丁烯)-苯乙烯三嵌段共聚物(SEBS)和一种苯乙烯-b-乙烯/丁烯((SEB)两嵌段共聚物为增容剂,对高密度聚乙烯(HDPE)/间规聚苯乙烯(sPS),共混物进行增容.采用扫描电镜(SEM)及拉伸试验研究了增容剂的分子量及结构对共混物形态结构及力学性能的影响.结果表明:3种增容剂SEBS (SEB)均可有效地降低sPS分散相的尺寸并增加HDPE/sPS共混物的界面强度,从而提高其力学性能.sPS的掺入可以显著提高HDPE的耐热性能.     

PP/HDPE/弹性体三元共混改性的研究

用双螺杆挤出机制备了聚丙烯(PP)/高密度聚乙烯(HDPE)/弹性体三元共混物,分别探讨了3种弹性体乙烯-辛烯嵌段共聚物(OBC)、苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)、苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物(SEBS)的含量对PP三元共混物力学性能的影响,并通过扫描电子显微镜观察其脆断表面形态。结果表明,OBC、SBS、SEBS和HDPE都对PP起到了一定的协同增韧作用,SEBS对PP的增韧效果最佳;SEM表明三元共混力学性能与相形态密切相关;所制备的PP/HDPE/OBC三元共混物的加工性能较好。     

Processability and thermal properties of blends of high density polyethylene,poly (ethylene terephthalate), and ethyl vinyl acetate compatibilizer

Because of differences in chemical structure and rheological characteristics, high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) are incompatible when blended during recycling of PET soft drink bottles. To improve the properties of the blends, ethylene vinyl acetate copolymer (EVA) was used as a compatibilizer. Based on torque rheometer tests, the higher the concentration of PET in the blends, the higher the initial loading torque. Blends of 50% HDPE and 50% PET had the lowest equilibrium torque. Equilibrium torque was highest at 5% EVA. The presence of EVA made only a slight difference in the glass transition temperatures of HDPE/PET blends. Higher EVA content in the blend resulted in a lower melting endotherm. Thermogravimetric analysis showed that thermal stability was independent of EVA content; but the more PET in the blend, the lower the final weight loss.     

Rheology behavior of high‐density polyethylene/diluent blends and fabrication of hollow‐fiber membranes via thermally induced phase separation

The phase‐separation behavior of high‐density polyethylene (HDPE)/diluent blends was monitored with a torque variation method (TVM). The torque variation of the molten blends was recorded with a rheometer. It was verified that TVM is an efficient way to detect the thermal phase behavior of a polymer–diluent system. Subsequently, polyethylene hollow‐fiber membranes were fabricated from HDPE/dodecanol/soybean oil blends via thermally induced phase separation. Hollow‐fiber membranes with a dense outer surface of spherulites were observed. Furthermore, the effects of the spinning temperature, air‐gap distance, cold drawing, and HDPE content on the morphology and gas permeability of the resultant membranes were examined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of HDPE/UHMWPE/MMWPE blends by two-step processing way and properties of blown films

Summary Blends of high density polyethylene (HDPE) and ultra high molecular weight polyethylene (UHMWPE) were prepared by two-step processing way. Middle molecular weight polyethylene (MMWPE) as a fluidity modifier and compatilizer was added into UHMWPE in the first step, and then modified UHMWPE and HDPE were blending extruded to prepare the HDPE/UHMWPE/MMWPE blends used for blown films. The mechanical test of the blown films revealed that when the content of MMWPE in modified UHMWPE was 40wt% and the content of UHMWPE in the blends was 20 wt%, the film had the optimal mechanical properties. The tensile strength and tear strength of the film increased by 50% and 21%, respectively, compared with those of pure HDPE film. Rheological curves indicated that the melt torque and the apparent viscosity of the HDPE/UHMWPE/MMWPE blends made by two-step processing way both greatly reduced than other blends. The results from DSC suggested that the blends by two-step processing way may form more stable and perfect co-crystallization. PLM (polarized light microscopy) and SEM micrographs revealed that two-step processing way can improve the surface morphology of the films and make the dispersion of UHMWPE particles in HDPE increase.     

增容剂对HDPE／AS合金流变和力学性能的影响

研究了增容剂氯化聚乙烯接枝（丙烯腈／苯乙烯）共聚物对ＨＤＰＥ／ＡＳ共混体系加工流变性能和力学性能的影响。增容剂使共混体系的塑化时间减少,且随着增容剂用量的增加,共混体系的平衡扭矩和拉伸强度增大,而断裂伸长率在ＨＤＰＥ／ＡＳ／ＰＥ－Ｃ－ｇ－ＡＳ＝８０／２０／４时出现极大值;螺杆转速的增加使共混体系的平衡扭矩增大。     

Effect of EPDM on the mechanical properties of blends of high and low density polyethylene

Summary We studied the effect of adding ethylene-propylene-diene rubber (EPDM) to blends of high (HDPE) and low (LDPE) density polyethylene. The extrusion torque of the blend without EPDM shows a deviation from the linear addition rule, but blends with rubber follow the addition rule. Two composition regions that are compatible with the torque behavior are present in the Young's modulus and extension at break curves. The EPDM content improves the extension at break of LDPE rich blends. This improvement extends to higher compositions of HDPE as the EPDM content is increased. Received: 4 September 1997/Revised version: 30 April 1998/Accepted: 13 May 1998     

Melt rheological properties of reactive compatibilized HDPE/PET blends

Melt rheological properties of high density polyethylene and poly(ethylene terephthalate) (HDPE/PET) blends compatibilized by an ethylene–butyl acrylate–glycidyl methacrylate terpolymer (EBAGMA) were studied by means of a HAAKE torque rheometer and a capillary rheometer. The phase morphology of the blends was evaluated by a scanning electron microscope (SEM). The results showed that the melts of blends behave pseudoplasticity. The addition of EBAGMA strengthens the interfacial adhesion between HDPE and PET and improves the phase dispersion due to reactive compatibilization. It was observed that the balance torque, melt viscosity, and sensitivity of melt viscosity to shear rate of the melts increase with increasing content of EBAGMA, but the melt flow index and activation energy decrease. At the same time, the plasticizing time is shortened indicating that the processability of the compatibilized blends has been improved. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Blends of high‐density polyethylene with solid silicone additive

Silicone masterbatch (SMB) is a pelletized formulation containing 50% of an ultrahigh molecular‐weight polydimethylsiloxane dispersed in polyethylene. This SMB is designed to be used as an additive in polyethylene‐compatible systems to impart benefits such as processing improvement and modification of surface characteristics. In this work, binary blends of high‐density polyethylene (HDPE) and SMB were prepared by melt‐mixing technique to study the influence of this masterbatch on the processing and mechanical properties of HDPE. Ternary blends were also prepared by the addition of silane‐grafted polyethylene (HDPE‐VTES) as compatibilizer. The blends were analyzed by melting flow rate (MFR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and tensile tests. Data of final torque and MFR showed that SMB improved the processability of pure HDPE. DSC results showed differences in crystalline behavior between binary and ternary blends. In the former, the degree of crystallinity increased up to 10 wt % of SMB content; beyond this concentration, it decreased. In ternary blends, a reverse behavior was observed. The morphologic study showed silicone particles uniformly distributed in HDPE matrix. With high SMB concentration, the addition of HDPE‐VTES significantly reduced the size of silicone particles. In the range of SMB composition studied, the mechanical properties of blends lower slightly compared to pure HDPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2347–2354, 2002     

High‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blend. I. The processing,thermal, and mechanical properties

Various blend ratios of high‐density polyethylene (HDPE) and ultrahigh‐molecular‐weight polyethylene (UHMWPE) were prepared with the objective of determining their suitability as biomaterials. Although the presence of HDPE in the blends enabled melt processing, the presence of UHMWPE helped to improve the toughness of the resulting blends. The processability of the blends was investigated with the Brabender torque, which was used as an indication of the optimum blend conditions. The blends were characterized with differential scanning calorimetry. The mechanical tests performed on the blends included tensile, flexural, and impact tests. A 50:50 (w/w) blend yielded optimum properties in terms of the processability and mechanical properties. The tensile property of the 50:50 blend was intermediate between those of HDPE and UHMWPE, but the strain at break increased 200% in comparison with that of both neat resins. The energy at break of the 50:50 blend revealed an improvement in the toughness. The fracture mechanism was also investigated with scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 413–425, 2005     

Study on morphology of ternary polymer blends. I. Effects of melt viscosity and interfacial interaction

The morphology of some ternary blends was investigated. In all of the blends polypropylene, as the major phase, was blended with two different minor phases, ethylene–propylene–diene terpolymer (EPDM) or ethylene–propylene–rubber (EPR) as the first minor phase and high‐density polyethylene (HDPE) or polystyrene (PS) as the second minor phase. All the blends were investigated in a constant composition of 70/15/15 wt %. Theoretical models predict that the dispersed phase of a multiphase polymer blend will either form an encapsulation‐type phase morphology or phases will remain separately dispersed, depending on which morphology has the lower free energy or positive spreading coefficient. Interfacial interaction between phases was found to play a significant role in determining the type of morphology of these blend systems. A core–shell‐type morphology for HDPE encapsulated by rubber was obtained for PP/rubber/PE ternary blends, whereas PP/rubber/PS blends showed a separately dispersed type of morphology. These results were found to be in good agreement with the theoretical predictions. Steady‐state torque for each component was used to study the effect of melt viscosity ratio on the morphology of the blends. It was found that the torque ratios affect only the size of the dispersed phases and have no appreciable influence on the type of morphology. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1129–1137, 2001