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。     

UHMWPE改性PPB和PPR的力学性能研究

研究了超高相对分子质量聚乙烯(UHMWPE)增韧改性的嵌段共聚聚丙烯(PPB)／UHMWPE和无规共聚聚丙烯(PPR)／UHMWPE的力学性能,采用红外光谱和扫描电镜对PPB,PPR和共混物的内部结构进行了分析。结果表明,UH- MWPE可以增韧PPB和PPR,PPB／UHMWPE断裂行为呈现网络结构破坏特征,而PPR／UHMWPE则发生脆-韧转变。     

高密度聚乙烯对改性聚丙烯共混体系力学性能的影响

采用熔融共混法制备聚丙烯(PP)/三元乙丙橡胶(EPDM)/滑石粉(Tacl)/(高密度聚乙烯)HDPE共混材料。研究了HDPE对改性PP共混体系力学性能的影响及其原因。结果表明,在PP/EP-DM/Tacl/HDPE共混体系中,HDPE的添加量存在一个饱和值,在这一添加量的前后,韧性和刚性指标曲线有波峰或波谷;不同牌号的2种HDPE,熔融指数高者增韧效果好。     

聚丙烯增韧性能的研究

用聚烯烃弹性体(POE)、高密度聚乙烯(HDPE)、线性低密度聚乙烯(LLDPE)对聚丙烯进行增韧改性,使其缺口冲击强度得到了很大的改善,尤其在低温时,POE显示出了比HDPE和LLDPE更加优异的增韧效果。结果表明,共聚聚丙烯比均聚聚丙烯更容易被POE,HDPE和LLDPE增韧。     

增韧高密度聚乙烯薄膜的结构与性能

以线型低密度聚乙烯(LLDPE)、聚丙烯(PP)及高熔体质量流动速率聚丙烯(HMIPP)对高密度聚乙烯(HDPE)进行增韧改性,利用熔体质量流动速率、落标冲击强度、雾度、红外光谱、扫描电镜、X射线衍射测试等研究改性HDPE薄膜的熔融温度、力学性能和形貌结构。结果表明,10%PP/30%LLDPE/HDPE配比增韧效果最佳,抗冲击质量从50 g提高到70 g,雾度从30%下降到24%,结晶温度由原来135. 21℃降低到115℃,改性HDPE发生塑性变形,PP和LLDPE与HDPE发生了物理交联,增韧后的HDPE薄膜结晶度下降了8%,PP和LLDPE加入提高了HDPE薄膜韧性。     

小型中空吹塑料的研制

采用CaCO3和HDPE对LLDPE进行改性,研究了CaCO3和HDPE用量对共混体系力学性能的影响。结果表明,当m（LLDPE）∶m（HDPE）∶m（CaCO3）=55∶30∶15时,体系的综合力学性能最好。HDPE对LLDPE具有增强增韧作用,此外,添加少量的CaCO3能显著改善共混材料的力学性能,所制得的改性材料可用于生产小型中空制品。     

无机纳米填料/PE复合体系对PP耐候性能的影响

将无机纳米材料、线性低密度聚乙烯(LLDPE)、高密度聚乙烯(HDPE)与聚丙烯(PP)熔融共混制备PP/LLDPE/HDPE/无机纳米耐候性复合材料。采用透射电子显微镜(TEM)、红外光谱仪(IR)、紫外-可见光谱仪(UW-V)以及力学性能测试等手段研究了聚乙烯(PE)/nano-SiO_2、PE/nano-TiO_2、PE/nano-ZnO复合体系对PP低温脆性和抗紫外老化性的影响。结果表明,复合材料中,无机纳米材料的质量分数为l%时,分散性最好,可促使PP与PE之间相互作用增强。PP/LLDPE/HDPE/nano-SiO_2低温抗冲击性能最好,温度为-10℃时其冲击强度保持率由纯PP的20.2%提高到了59.3%;PP/LLDPE/HDPE/nano-TiO_2的抗紫外线老化性能最好,老化144 h后断裂伸长率和冲击强度保持率分别提高到了43.9%和48.0%。     

UHMWPE/HDPE共混体系的流动性和力学性能研究

将一定量超高分子量聚乙烯(UHMWPE)引入高密度聚乙烯(HDPE)中构成共混体系,通过对共混体系的熔体质量流动速率(MFR)、拉伸屈服强度、弯曲性能、冲击强度进行研究,探讨了不同质量分数、不同相对分子质量的UHMWPE对UHMWPE/HDPE共混体系的流动性和力学性能的影响。     

BHDPE/HDPE/LLDPE共混体系的研究

采用线性低密度聚乙烯(LLDPE)对双峰高密度聚乙烯(BHDPE)和高密度聚乙烯(HDPE)进行共混,测定共混物的力学性能和DSC曲线。结果显示共混物均可以产生共晶,LLDPE对BHDPE力学性能影响较大;在LLDPE/HDPE中添加BHDPE,三者共混物具有更好的力学性能,流变性能显示三者共混物体系黏度变化不大,为制备性能最优、成本最低的三者共混物提供了依据。     

拉伸流动作用下CFs/UHMWPE/HDPE共混物的制备及性能

介绍了一种拉伸流动支配的叶片挤出机的结构及其熔融塑化过程,利用该设备制备了碳纤维(CFs)/超高分子量聚乙烯(UHMWPE)/高密度聚乙烯(HDPE)共混物,研究了CFs和UHMWPE含量对共混物微观形貌、结晶性能和力学性能的影响。SEM图像表明,拉伸流动支配的叶片挤出机对CFs和UHMWPE有很好的分散混合效果;DSC分析结果表明,低含量的CFs和UHMWPE可以协同提高共混物的结晶度;加入适量的CFs和UHMWPE可使共混物的拉伸强度明显提升,当UHMWPE含量为8%、CF含量为12%时,CFs/UHMWPE/HDPE共混物拉伸强度与HDPE纯料相比,提高了23.4%;与CFs/HDPE共混物相比,加入UHMWPE可以有效缓解共混物冲击强度的降低,当UHMWPE含量为12%时,CFs/UHMWPE/HDPE共混物的冲击强度与CFs/HDPE共混物相比,提高了29.7%。     

UHMWPE/HDPE共混物的流动性及力学性能的研究

采用不同MFR的HDPE与UHMWPE进行熔体共混。结果表明UHMWPE／HDPE共混物流动性和力学性能的变化受体系组成、熔体粘度比等因素的影响较大。HDPE的MFR过高、过低或用量过多，均不利于共混物流动性及综合力学性能的改善。当HDPE作为分散相时，易于实现向UHMWPE高粘弹粒子的渗透、分散及结合，共混物的．MFR及拉伸屈服强度、断裂强度、断裂伸长率均比UHMWPE有提高，共混物表现出协同效应；当UHMWPE为分散相或二者熔体粘度比差异过大时，混合效果变差，共混物综合力学性能下降；在某些中间配比下，二者表现出增链缠结效应，共混物MFR明显降低。     

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。     

UHMWPE共混改性HDPE薄膜性能的研究

采用中等摩尔质量聚乙烯（MMWPE）首先对超高摩尔质量聚乙烯（UHMWPE）进行改性，然后通过两步共混法制备了HDPE／UHMWPE共混吹塑薄膜，研究了共混物的力学、流变性能以及MMWPE对UHMWPE力学和流变性能的影响。实验结果表明，当改性UHMWPE中的MMWPE的质量分数为40％时，改性UHMWPE的力学性能下降不大，而流变性能大大改善。两步法制得的HDPE／UHMWPE薄膜表面的晶点明显减少，比一步法得到的薄膜的拉伸强度和撕裂强度分别提高了20％和12％，比纯HDPE的分别提高45％和21％。     

超高相对分子质量聚乙烯对双峰HDPE树脂性能的影响

为了提高双峰高密度聚乙烯（HDPE）的力学性能,采用超高相对分子质量聚乙烯（UHM—WPE）与双峰HDPE以不同比例共混,对共混物的相对分子质量及其分布、热性能、流变性能和力学性能进行了测试。UHMWPE的加入使高相对分子质量部分显著增加,流变性能下降,添加量小于10％（质量分数）时,共混物粘度在高剪切速率下变化不大;UHMWPE可提高共混物的熔融温度和初始结晶温度,结晶度先增加然后迅速降低;随着UHMWPE含量的增加,混合物的拉伸强度也随之增加,呈线性关系;结晶度与冲击强度成反比。     

Dynamic mechanical properties,crystallization behaviors,and low‐temperature performance of polypropylene random copolymer composites

In this study, polypropylene random copolymer (PPR) composites were prepared by the addition of either three kinds of thermoplastic rubber (TPR) modifiers (types 2088A, 2095, and 2096) or an ethylene–octene copolymer (POE)/high‐density polyethylene (HDPE; 2 :1 w/w) blend. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and dynamic mechanical analysis were used to characterize the crystallization behaviors and dynamic mechanical properties of the PPR composites. The results indicated that PPR/POE/HDPE and PPR/TPR2088A had better comprehensive mechanical properties, especially the low‐temperature toughness among all of the samples. The obtained PPR/POE/HDPE blends showed a high toughness and good stiffness in the temperature interval from ?10 to 23°C with the addition of only 10 wt % POE/HDPE. When the temperature continued to fall below ?10°C, the PPR/TPR2088A composites exhibited a better impact toughness without a loss of too much stiffness. The good low‐temperature toughness of those two composites was attributed to both the decrease in the crystallinity and the uniform dispersion, obvious interfacial adhesion, and cavitation ability of POE/HDPE and TPR2088A in the PPR matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42960.     

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/UHMWPE/纳米HA生物复合材料性能的影响

通过熔融共混法制备了高密度聚乙烯/超高分子量聚乙烯/纳米羟基磷灰(石HDPE/UHMWPE/纳米HA)生物复合材料,研究了增容剂三元乙丙橡胶接枝马来酸(酐EPDM-g-MAH)和聚烯烃弹性体接枝马来酸酐(POE-g-MAH)对复合材料力学性能的影响,并利用红外光谱、扫描电镜、热重分析仪及熔体流动速率仪表征了复合材料的微观结构、热性能和流动性能。结果表明:EPDM-g-MAH和POE-g-MAH均可提高HDPE/UHMWPE/纳米HA复合材料的相容性,其中EPDM-g-MAH的增容效果更明显;随着增容剂用量的增大,复合材料的熔体流动速率、热变形温度和热稳定性逐渐下降;与添加POE-g-MAH相比,含有EPDM-g-MAH的复合材料的综合性能较好。     

Exploring the entangled state and molecular weight of UHMWPE on the microstructure and mechanical properties of HDPE/UHMWPE blends

Three types of ultra-high molecular weight polyethylene (UHMWPE) with different entangled state and molecular weight were blended with high-density polyethylene (HDPE) matrix by melt blending. Rheology, 2D-SAXS, 2D-WAXD, DSC, and mechanical tests were used to study the evolution and difference of microstructure and mechanical properties of the blends. The addition of weakly entangled UHMWPE enhanced the chain diffusion and chain orientation ability under a specific flow field. Thus, the rheological properties and mechanical properties of the blends were improved with the mix of weakly entangled UHMWPE. The mechanical properties enhancement effect of HDPE/UHMWPE blends with weakly entangled UHMWPE was owing to the shish-kebab structure formed in the injection molding process. The molecular chains of UHMWPE with a low degree of entanglement and high molecular weight increased the lamella size and crystallinity of the blends during processing. This leads to the formation of more oriented shish structures and more kebab lamella. Besides, the molecular chains of weakly entangled UHMWPE were better interlocked and intertwined with other polyethylene chains in the amorphous region, acting as the tie molecules, significantly improving the impact resistance.