超临界CO_2辅助UHMWPE/PP挤出成型研究

对超临界CO2辅助UHMWPE/PP共混体系的挤出成型进行了研究。结果表明,在挤出成型过程中,超临界CO2对UHMWPE/PP体系起到一定的增韧作用,使其力学性能有所改善。同时超临界CO2作为一种增塑剂,降低了UHMWPE/PP体系的黏度,改善了体系的流动性和加工性能。     

聚丙烯/超高相对分子质量聚乙烯共混物的结晶动力学及发泡性能研究

采用差示扫描量热仪（DSC）对含有不同含量超高分子量聚乙烯（UHMWPE）的聚丙烯进行测试和表征,采用Ozawa方法、莫志深方法和Kissinger方法分析了该体系的非等温结晶动力学。利用自行研制的超临界流体挤出发泡实验装置,对含有UHMWPE的PP进行了超临界二氧化碳挤出发泡实验研究。结果表明：超高分子量聚乙烯的加入降低了PP的结晶活化能,含有UHMWPE的PP在较高的温度下开始结晶,且由于超高分子量聚乙烯大分子链的存在,与聚丙烯分子链发生缠结,阻碍聚丙烯分子链排入晶格,降低了结晶速率,结晶温区拓宽,有利于聚丙烯挤出发泡成型;加入UHMWPE后,PP的发泡效果明显改善,泡孔平均直径减小,泡孔尺寸分布更加均匀,PE-UHMW的含量为5份时,表观密度达到0.038g/cm-3。     

超临界CO2辅助加工对PP/滑石粉复合材料性能的影响

在共混挤出聚丙烯(PP)/滑石粉复合材料过程中,通入二氧化碳以辅助加工并由此保护滑石粉的微观片状结构。研究了超临界二氧化碳(SC-CO2)通气量、加工温度、螺杆转速对滑石粉微观片状结构形貌和复合材料性能的影响。结果表明:CO2通气量越大、加工温度越高,加工过程中滑石粉的微观片状结构被破坏程度越小;螺杆转速越高,滑石粉的微观片状结构被破坏程度越大;微观片状结构破坏程度较小的滑石粉,其PP/滑石粉复合材料的拉伸模量和弯曲模量较高。     

超高分子量聚乙烯/聚丙烯共混改性研究进展

超高分子量聚乙烯(UHMWPE)的加工一直是一个世界性难题。采用聚丙烯(PP)改性UHMWPE可显著提高UHMWPE的加工性能并保持较好的力学性能,因而UHMWPE/PP共混体系的研究受到广泛关注。本文首先介绍了限制UHMWPE加工成型的主要原因,其次从相态结构、流动性能、力学性能及耐磨性能等方面综述了近年来UHMWPE/PP共混改性的研究进展,最后对其发展方向进行了展望。     

UHMWPE/PP的共混改性

采用自行配制的解缠剂Jc 3降低UHMWPE的熔体粘度,并用机械共混的方法进行加工,从而实现PP与UHMWPE之间的均匀共混,以改善共混体系的力学性能。研究了原料配方及加工工艺对共混体系力学性能的影响。结果表明:解缠剂能够有效改善共混体系的混合程度;UHMWPE的用量和Jc 3的用量对共混物力学性能有不同的影响;采用先开炼再挤出而后注射的加工工艺得到的制品力学性能较好。     

超临界CO2辅助PTFE/PP挤出的研究

研究了超临界CO2辅助聚四氟乙烯(PTFE)/聚丙烯(PP)共混体系的挤出成型过程。结果表明,超临界CO2辅助挤出成型过程中,超临界CO2对PTFE/PP体系能起到一定的增韧作用,并且超临界CO2作为一种增塑剂,能降低PTFE/PP体系的粘度,改善体系的流动性和加工性。     

原位增强聚丙烯/液晶复合材料结构与性能研究

利用自制的复合拉伸挤出成型口模对材料进行拉伸挤出,并探讨添加不同含量的液晶材料对聚丙烯（PP）结构与性能的影响。结果表明,少量的液晶聚合物在PP基体中形成了纤维结构,当液晶的添加量为10份时,复合材料的力学性能最大可提高25.2%,热变形温度提高21.1℃;适量的液晶的加入有利于改善PP材料的流动性能,有利于PP基体结晶度的改善。     

HDPE/UHMWPE共混物的制备及其性能

采用不同螺纹块组合的双螺杆挤出机制备HDPE/UHMWPE共混物,研究UHMWPE用量、螺杆结构对共混物力学性能、流变行为及分散形态的影响.结果表明:随着UHMWPE用量的增加,共混物的拉伸和缺口冲击强度随之增加,特殊螺杆挤出机制备共混物的机械性能均比普通螺杆的提高.UHMWPE使共混物成型加工黏度增大,特殊螺杆能降低共混物成型加工黏度.偏光显微镜照片显示,特殊双螺杆挤出机使UHMWPE熔融程度和分散程度增大.     

高流动性共聚聚丙烯HHP10的研发

利用反应挤出技术,研究了聚丙烯(PP)及成核剂在过氧化物的作用下在反应挤出机中进行可控降解的规律,考察了基础树脂、助剂体系、加工条件对最终产品力学性能的影响。实验表明:在PP中加入少量的过氧化物便能显著改善其熔体流动速率;加入含有辅助抗氧剂及成核剂的复配助剂体系能显著提高PP的力学性能、氧化诱导期、黄色指数等;根据简便方法测试出物料在挤出机中的停留时间,通过对应过氧化物的半衰期,确定所需的加工条件。     

振动场中HDPE/UHMWPE及其吹塑薄膜的性能

利用电磁振动挤出机制备高密度聚乙烯/超高相对分子质量聚乙烯(HDPE/UHMWPE)共混物,对比了静态和动态下共混吹塑薄膜的力学性能及薄膜的表观,用振动毛细管流变仪测定了静态和动态下共混物的流变行为,用差示量热扫描仪(DSC)探讨了共混物的结晶行为。结果表明,电磁振动挤出机制备的共混物吹制薄膜的力学性能均比稳态下的高;振动态时共混物的结晶度高,结晶峰型更为尖锐;振动力场中的共混物的表观粘度低于稳态的,振动力场改善HDPE/UHMWPE共混物的成型加工性能。     

Extrusion of ultrahigh molecular weight polyethylene under ultrasonic vibration field

The effects of polypropylene (PP) and ultrasonic irradiation on the processing and mechanical properties of ultrahigh molecular weight polyethylene (UHMWPE) are studied. The results show that PP can effectively improve the fluidity and mechanical properties of UHMWPE. The Izod notched impact strength increases from 92 kJ/m² for pure UHMWPE to 109.2 kJ/m² for the blend of UHMWPE with 10 wt % PP. The Young's modulus increases from 528 MPa for pure UHMWPE to 1128 MPa when 25 wt % PP is contained in the blend, and the yield strength also rises when PP is added. The application of ultrasonic vibrations during extrusion can prominently decrease the die pressure and apparent viscosity of the melt, thus increasing the output of extrudate. An appropriate ultrasonic intensity and irradiation time can further promote the mechanical properties, while an overdose of irradiation destroys them. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2628–2632, 2003     

Synchronous toughening and reinforcing of polypropylene with ultrahigh‐molecular‐weight polyethylene via melt blending: Mechanical properties,morphology, and rheology

Blending systems based on polypropylene (PP) and ultrahigh‐molecular‐weight polyethylene (UHMWPE) were prepared via a melt extrusion by the four‐screw and the twin‐screw extruders, respectively. The mechanical evaluation demonstrated that the synchronous toughening and reinforcing effects could be achieved from the combination of the PP and the UHMWPE, in which the toughness and the tensile properties could be improved with increasing the UHMWPE content, and achieved optimal values at a weight ratio of PP/UHMWPE (85/15). EPDM can be used as a compatibilizer to improve the compatibility and the interfacial adhesion between the PP and the UHMWPE. This resulted in more effective toughening and reinforcing effects. In contrast, for the PP/UHMWPE blends prepared by the normal twin‐screw extruder, the poor dispersion capacity for the UHMWPE resulted in a deterioration of all mechanical parameters. Morphological observation revealed that the UHMWPE domain was well distributed as tiny particles in the PP matrix, which was confirmed by the differential scanning calorimetry analysis. The toughening effect was attributed to the energy dissipation caused by these rigid tiny particles that detached from the matrix to initiate the local matrix shear yield and formed the void. Rheological investigation demonstrated that there was an interesting composition dependence of viscosity, for which the melt viscosities of the PP/UHMWPE blends decreased when 5 wt % UHMWPE was added, and then began to increase as the UHMWPE content continued to increase. However, this dependence on composition became weaker because of the compatibilization of the EPDM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3498–3509, 2006     

PP/超临界CO2连续挤出发泡成型

以超临界CO2为发泡剂,在连续挤出发泡过程中研究了超临界CO2用量对高熔体强度均聚聚丙烯(PP)发泡成型过程的影响.随着超临界CO2用量的增加,发泡挤出机口模压力降低,试样发泡倍率降低,泡孔尺寸变小,泡孔密度提高.在w(CO2)为3%,5%时,得到发泡倍率最高为13左右的PP发泡材料.w(CO2)为7%,发泡温度为12...     

Influence of poly(ethylene glycol)‐containing additives on extrusion of ultrahigh molecular weight polyethylene/polypropylene blend

The influence of poly(ethylene glycol) (PEG)‐containing additives on the extrusion behavior of ultrahigh molecular weight polyethylene/polypropylene (UHMWPE/PP) blend was studied. It was found that the addition of small amounts of PEG to UHMWPE/PP blend resulted in significant reduction of die pressure and melt viscosity, and obvious increase of the flow rate at a given die pressure, while PEG/diatomite binary additives enhanced the improvement in the processability of UHMWPE/PP blend. When pure HDPE was extruded with the die through which UHMWPE/PP/PEG blend was previously extruded, the extrusion pressure of HDPE increased with the extrusion time gradually. This meant that PEG might migrate to the die wall surface and coat it in the extrusion of UHMWPE/PP/PEG blend. FTIR spectra and SEM micrographs of the UHMWPE/PP/PEG extrudates indicated that PEG located not only at the surface but also in the interior of the extrudates. So, the external lubrication at the die wall, combined with the internal lubrication to induce interphase slippage of the blend, was proposed to be responsible for the reduction of die pressure and viscosity. In addition, an ultrahigh molecular weight polysiloxane and a fluoropolymer processing aid were used as processing aids in the extrusion of UHMWPE/PP as control, and the results showed that only minor reduction effects in die pressure and melt viscosity were achieved at their suggested loading level. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1282–1288, 2006     

UHMWPE改性PP共混物的力学性能

研究了UHMWPE型号及UHMWPE的用量对PP材料力学性能的影响。结果表明:在PPH/PPR/PPB为60/20/20时分别加入UHMWPE2401和UHMWPE2402,可起到增强增韧的效果,在开炼机上制试样UHMWPE2402的效果要好于UHMWPE2401,注射制样为UHMWPE2401好于UHMWPE2402;随UHMWPE含量的增加,PPH/PPR/PPB共混物的缺口冲击强度大体呈直线上升趋势,在UHMWPE2401为20份时,达到29 4kJ/m2。     

Study on processing of ultrahigh molecular weight polyethylene/polypropylene blends: Capillary flow properties and microstructure

The capillary flow properties and morphologies of ultrahigh molecular weight polyethylene/polypropylene (UHMWPE/PP) blends were studied. The results show that UHMWPE is difficult to process. The melts flowed unsteadily at lower shear rate. With 10 wt % PP contained in the UHMWPE/PP blends, the apparent melt viscosity was much lower than that of UHMWPE. When the PP content increased to 20 and 30 wt %, no pressure vibration occurred throughout the whole shear rate range. Microstructure analysis showed that PP prefers to locate in the amorphous or low crystallinity zones of the UHMWPE matrix. The flowability of UHMWPE increased substantially with the addition of PP. The addition of PE could not effectively reduce the chain entanglement density of UHMWPE. The improvement of processability of UHMWPE by the addition of PE was rather limited. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3894–3900, 2004     

Effect of gamma ray irradiation on processability and properties of ultra high molecular weight polyethylene

Ultra high molecular weight polyethylene (UHMWPE) has been widely used in many fields due to its outstanding properties. However, it is virtually impossible to be processed by the conventional method due to its high molecular weight and very tight chain entanglement. To solve this problem, a new method was proposed in this article. Gamma ray irradiation was adopted to cause the oxidation degradation of UHMWPE. The degraded products which generated in situ and dispersed in UHMWPE evenly were utilized as self‐lubricant and heat transfer intermediary. These low molecular weight fractions thus could improve the processability of UHMWPE. The effects of irradiation dose on the structure and properties of UHMWPE were studied by fourier transform infrared (FTIR) spectroscopy, gel content measurement, wide angle x‐ray diffraction (WAXD), Haake torque rheometer, mechanical properties measurements and sliding wear tests. The experimental results showed that gamma ray irradiation caused oxidation degradation of UHMWPE. Under appropriate irradiation condition, the processability of UHMWPE could be improved substantially while most of its excellent properties could be kept. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Study on processing of ultrahigh molecular weight polyethylene/polypropylene blends

The processing of ultrahigh molecular weight polyethylene (UHMWPE) by the addition of polypropylene (PP) and high‐density polyethylene (HDPE) was investigated. The results show that the addition of PP improves the processability of UHMWPE more effectively than does the addition of HDPE. UHMWPE/PP blends can be effectively processed with a twin‐roller and general single‐screw extruder. In the extrusion of UHMWPE/PP blends, PP is enriched at the surface of the blend adjacent to the barrel wall, thus increasing the frictional force on the wall; the conveyance of the solid down to the channel can then be carried out. The melt pool against the active flight flank exerts a considerable pressure on the UHMWPE powder in the passive flight flank, which overcomes the hard compaction of UHMWPE. The PP penetrates into the gaps between the particles, acting as a heat‐transfer agent and adhesive, thus enhancing the heat‐transfer ability in the material. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 977–985, 2004     

PP/UHMWPE及含有不同添加剂共混物的研究

采用超高分子质量聚乙烯对聚丙烯进行改性,同时采用了3种不同的添加剂PP-MAH、LLDPE、SBS,希望能进一步提高改性效果。通过两次熔融混合制备PP/UHMWPE及含有不同添加剂的共混物,对其力学性能进行测试及表征。实验结果表明,UHMWPE在基体中形成物理交联的网络结构,可在冲击作用下吸收、传递大量的冲击能,从而有...