UHMWPE／UHMWPP冻胶体系的流变行为研究

研究了超高相对分子质量聚丙烯（UHMWPP）的加入对超高相对分子质量聚乙烯（umfwPE）冻胶体系粘性行为、非牛顿指数、结构粘度指数的影响。结果表明：UHMWPP在UHMWPE／UHMWPP共混体系中起到了润滑剂的作用,使体系的表观粘度降低,非牛顿指数升高,结构粘度指数下降。其中,UHMWPP添加量为5％时,冻胶体系的可纺性最佳。     

PP/黏土纳米复合材料的结构与性能

采用熔体插层法制备聚丙烯（PP）/有机黏土（OMMT）纳米复合材料。XRD和TEM的测试结果表明,采用熔体插层法制备的PP/OMMT复合材料是剥离型纳米复合材料。力学性能实验结果表明,相容剂的加入提高了PP与OMMT之间的相互作用,使其各项力学性能都得到了提高;PP/OMMT纳米复合材料的各项力学性能在有机黏土含量较小的情况下,就可以有较大幅度的提高;与纯PP相比,相容剂含量为10 phr、有机黏土用量为1 phr的聚丙烯基纳米复合材料具有最好的各项力学性能。     

PP/MWNTs和PP/OMMT复合材料的热降解动力学研究

采用熔融共混法制备了聚丙烯/多壁碳纳米管(PP/MWNTs)与聚丙烯/纳米有机蒙脱土(PP/OMMT)复合材料,利用热重分析法研究了PP、PP/MWNTs及PP/OMMT在氮气气氛中的热降解过程,并采用Kissinger及Ozawa方法研究了复合材料的热降解动力学及热降解表观活化能.结果表明,MWNTs和OMMT的加入...     

PP／UHMWPE合金增韧增强机理研究

采用超高相对分子质量聚乙烯（UHMWPE）对乙丙共聚型聚丙烯（PP）进行共混改性，所得合金材料的刚性和韧性同时得到显著提高，其缺口冲击强度大于72.1kJ/m^2，断裂伸长率大于900％。采用多种测试手段从共混物性能与结构关系出发，探讨了合金高性能化的深层原因。认为在适当的工艺条件下，UHMWPE能以其较高的熔体粘度和强度在PP基体中以微纤状均匀分散，并与PP形成双连续相结构。在熔体冷却过程中，UHMWPE的高分子链段与PP基体的部分PE链段形成共晶，产生一种“共晶物理交联点的互穿网络结构”，从而使合金的韧性和刚性同时得以提高。     

PE-UHMW/PP共混物的流动、力学与耐磨损性能研究

将均聚型聚丙烯(PP)、耐磨助剂与超高分子量聚乙烯(PE-UHMW)共混,制备了PE-UHMW/PP共混物,研究了PP含量及耐磨助剂对PE-UHMW/PP共混物流动、力学与耐磨损性能的影响。结果表明,PP能有效地改善PE-UHMW的流动性能,PE-UHMW/PP共混物的维卡软化点和热变形温度均随PP含量的增加而增加;加入耐磨助剂后,当PP的质量分数为50%时,共混物的拉伸强度达到最大,但断裂伸长率最小,且随PP含量的增加,PE-UHMW/PP共混物的冲击性能降低;PP降低了PE-UHMW的耐磨损性能,加入耐磨助剂后保持了PE-UHMW的高耐磨损性能且对共混物的流动和力学性能影响不大。     

Ultrahigh molecular weight polyethylene/polypropylene/organo‐montmorillonite nanocomposites: Phase morphology,rheological, and mechanical properties

Phase morphology, rheological, and mechanical properties of ultrahigh molecular weight polyethylene (UHMWPE)/PP/organo‐montmorillonite nanocomposites were investigated in this work. The results of TEM and XRD indicated that the organo‐montmorillonite PMM prepared with the complex intercalator [2‐methacryloyloxyethyldodecyldimethylammonium bromide/poly(ethylene glycol)] were exfoliated and dispersed into UHMWPE matrix, and the synergistic effect of the complex intercalator on the exfoliation and intercalation for montmorillonite occurred. Besides, the presence of PMM in UHMWPE matrix was found able to lead to a significant reduction of melt viscosity and enhancement in tensile strength and elongation at break of UHMWPE, except that izod‐notched impact strength was without much obvious change. The dispersed PMM particles exhibited a comparatively large two‐dimensional aspect ratio (L_clay/d_clay = 35.5), which played an important role in determining the enhancement of mechanical properties of UHMWPE nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

UHMWPE/PEG共混方式及配比对UHMWPE缠结行为及性能的影响

超高分子量聚乙烯（UHMWPE）是常用的高性能聚合物。由于高黏度的影响,极大地限制了其加工成型与应用。聚乙二醇（PEG）具有高流动性,被广泛用来改善UHMWPE的流变行为,但复合材料中添加相的分散效果对材料的性能有重要影响。采用干粉混合、溶液混合、熔融挤出共混等方式制备了不同配比UHMWPE/PEG复合材料。基于熔融拉伸实验研究了共混方式及配比对UHMWPE缠结行为及性能的影响。结果表明,PEG的加入降低了复合材料的链缠结密度。三种混合方式中,加入5%PEG时干粉混合与挤出混合解缠作用较明显,链缠结密度均降低26%左右。     

Influence of reactive compatibilization on the structure and properties of PP/LDH nanocomposites

Polypropylene (PP)/layered double hydroxide (LDH) nanocomposites were prepared by the direct melt intercalation method using maleic anhydride grafted polypropylene (PP‐g‐MAH) as a reactive compatibilizer. The compatibilization effects provided by PP‐g‐MAH in different weight fractions and their influence on the structure and properties of the final nanocomposites were investigated. The interactions and structural morphology of the nanocomposites were examined by Fourier transform infrared spectroscopy, X‐ray diffraction and transmission electron microscopy. Thermal, mechanical and rheological properties of these nanocomposites were investigated as a function of compatibilizer concentration. The detailed morphological and X‐ray diffraction results revealed that the degree of LDH dispersion increases as the amount of PP‐g‐MAH increases. Study of the linear viscoelastic properties showed that the storage modulus G′ is very sensitive to the microstructure of the nanocomposite. The thermal properties of the nanocomposites were significantly influenced by the weight fraction of PP‐g‐MAH due to the shielding and nucleating effect of exfoliated layers. Both the tensile strength and modulus showed substantial improvements with increasing PP‐g‐MAH content, while the elongation at break substantially decreased, although the presence of PP‐g‐MAH somewhat improves these values. The overall results showed that 10 wt% of compatibilizer is optimum to achieve nanocomposites with better performance. Copyright © 2011 Society of Chemical Industry     

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     

有机蒙脱土对PA6/PP合金体系的作用机制及其对材料性能的影响

研究了有机蒙脱土对PA6/PP合金体系的作用机制及其对材料性能的影响。结果表明,OMMT的添加可以提高体系的拉伸强度、弯曲强度和弯曲模量,但冲击强度会有某种程度的下降;OMMT主要分散在PA6连续相中,且当其添加量质量份数低于5%时,可以在PA6相中实现较充分的剥离;OMMT对PA6/PP合金体系有着显著的增容作用,这可能和片层对PP分散相凝聚时的阻隔,以及片层所起到的类似接枝物的增容作用有关;OMMT在PA6基体中被充分剥离后,将有利于使复合体系的拉伸强度、弯曲强度得到提高,但OMMT片层及和片层有关的类似接枝物的存在,将束缚并限制界面层附近PP相的屈服,而使材料冲击韧性下降。     

相容剂作用下超高相对分子质量聚乙烯增韧聚丙烯共混体系的研究

选取不同相容剂[马来酸酐接枝聚丙烯、线形低密度聚乙烯、丙烯腈-丁二烯-苯乙烯共聚物（ABS）]增容聚丙烯/超高相对分子质量聚乙烯（PP/PE-UHMW）共混体系,对比不同相容剂作用下PP/PE-UHMW共混体系力学性能的差异,并研究了PP/PE-UHMW/相容剂共混体系的亚微相结构,进一步探讨了微观结构对PP/PE-UHMW共混体系力学性能的影响。结果表明,添加相容剂的三元共混体系的结晶颗粒呈细化趋势;相容剂ABS的增容效果较好,PP/PE-UHMW/ABS共混体系的冲击强度最高可达113.31 J/m,并可保持PP原有的拉伸强度,但其断裂伸长率有较大幅度的降低。     

Effects of ultrasonic oscillations on rheological behavior and mechanical properties of novel propylene‐based plastomers

The effects of ultrasonic oscillations on the die pressure, productivity of extrusion, melt apparent viscosity, melt surface appearance, and die swell of novel propylene‐based plastomers were studied in a specially designed ultrasonic oscillations extrusion system developed in our laboratory. The effects of ultrasonic oscillations on molecular weights, tensile strength, and dynamic mechanical properties of extrudates were also studied. The experimental results showed that the presence of ultrasonic oscillations during extrusion could significantly increase the productivity of plastomers at the same die pressure, and reduce die swell and melt fracture such as sharkskin at a given screw rotation speed. The die pressure and apparent viscosity of plastomers remarkably decreased with increasing ultrasonic intensity. Introduction of ultrasonic oscillations into plastomer melts can improve their processibility. The possible mechanism for ultrasonic improvement of rheological behavior was also proposed in this article. Under certain conditions, ultrasound‐assisted extrusion could slightly decrease the glass transition temperature (T_g) and storage modulus of plastomers due to the minor reduction in molecular weights, but showed no significant impact on yield strength and strength at break. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

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。     

分子量对UHMWPE干摩擦条件下的销-盘摩擦磨损行为的影响

采用销-盘试验,在转速为60 r/min,法向为载荷(392±29)N,聚合物盘与钢销摩擦副接触形式为面-面,试验时间为1.5 h,试验环境温度为20℃,相对湿度为60%的条件下,研究了200万、300万、500万和900万分子量的UHMWPE分别与钢配副干摩擦时UHMWPE分子量对其摩擦磨损性能的影响,并利用扫描电子显微镜观察其磨损表面形貌。结果表明:UHMWPE分子量其摩擦磨损性能有显著影响,UHMWPE的分子量为300万时,摩擦副的摩擦因数及UHMWPE自身的磨损为最小。     

Novel intercalated nanocomposites of polypropylene/organic‐rectorite/polyethylene‐octene elastomer: Rheology,crystallization kinetics,and thermal properties

The melt blending method was applied to prepare ternary composites of polypropylene (PP)/organic‐rectorite (OREC)/polyethylene‐octene elastomer (POE) at constant content of 2 phr (parts per hundred PP) of OREC and 5, 10, 15 phr of POE (named PRE25, PRE210, and PRE215, separately) via twin‐screw extruder. At the same time the binary composites of OREC/PP at 2 phr loading of OREC, named PR2 were prepared in order to investigate effects of OREC and POE on rheology and crystallization properties of composites. The rheology was characterized on capillary rheometer, nonisothermal crystallization kinetics on differential scanning calorimetry (DSC), and thermal stability properties on thermogravimetric analysis (TG). It is found that melting PR2 and PRE systems conform to the law of Non‐Newton and shear‐thinning behavior is observed for both systems. The apparent viscosity of the melt decreases with the increase of POE loadings. The crystallization halftime (t_1/2) of PRE is shorter, the rate constant Zc larger, which indicates OREC and POE has the heterogeneous nucleation effect and the crystallization rate of PP was increased. The enthalpy of PRE is lower than that of PR2 and pure PP at the same conditions, which shows that the relative crystallinity of PRE composites are reduced. TG curves show that the ternary systems have higher thermal stability in contrast with pure PP. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1915–1921, 2005     

Influence of water content,time, and temperature on the rheological behavior of polyethylene terephtalate

In this work, the main factors affecting the rheological behavior of polyethylene terephtalate (PET) in the linear viscoelastic regime (water content, time delay before test, duration of experiment, and temperature) were accessed. Small amplitude oscillatory shear tests were performed after different time delays ranging from 300 to 5000 s for samples with water contents ranging from 0.02 to 0.45 wt %. Time sweep tests were carried out for different durations to explain the changes undergone by PET before and during small amplitude oscillatory shear measurements. Immediately after the time sweep tests, the PET samples were removed from the rheometer, analyzed by differential scanning calorimetry and their molar mass was obtained by viscometry analysis. It was shown that for all the samples, the delay before test and residence time within the rheometer (i.e. duration of experiment) result in structural changes of the PET samples, such as increase or decrease of molar mass, broadening of molar mass distribution, and branching phenomena. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The Effect of Compatibilizer on Morphology and Mechanical Properties of PA6/UHMWPE Blends

Abstract

This work deal with the effect of compatibilizer on the morphological and mechanic properties of polyamide 6 and ultrahigh molecular weight polyethylene (PA6/UHMWPE) blends. The blends were prepared by means of a twin-screw extruder. The compatibilizer was produced by grafting maleic anhydride (MAH) onto high density polyethylene (HDPE). The resulting HDPE-g-MAH was used to prepare ternary blends of PA6/HDPE-g-MAH/UHMWPE by melt mixing. The size of domain of UHMWPE in PA6/HDPE-g-MAH/UHMWPE blends is much smaller than that in PA6/UHMWPE blends. It was found that mechanical properties of PA6/HDPE-g-MAH/UHMWPE blends obviously surpassed that of PA6/UHMWPE blends. These behavior could be attributed to chemical reactions between MAH in HDPE-g-MAH and terminal amino groups of PA6. Thermal analysis were performed to confirm the possible chemical reactions taken place during the blending process.     

强剪切分散混炼器对聚丙烯流变行为的影响

利用自行研制的多级磨盘式强剪切分散混炼器，研究了聚丙烯经过混炼器作用后的流变行为。通过测定混炼器不同转速下制得的聚丙烯试样的熔体流动速率值，结合GPC对其相对分子质量及相对分子质量分布的测试结果，表明聚丙烯经混炼器的强剪切作用后发生了显著的分子链断链现象，其中在5r／min的元件转速下，PP的MW、Mx和Mx＋1分别降低了33．4％、66％和83．7％，而其力学性能并无明显降低；因机械力断链而产生的活自由基，会引发进一步的降解和交联等高分子力化学反应。     

转速及温度对PE-HD/PP/SGF管材分子取向的影响

利用自行设计制造的剪切拉伸双向复合应力场挤管装置生产出了双向增强的高密度聚乙烯/聚丙烯/短玻璃纤维(PE-HD/PP/SGF)管材,研究分析了该装置中剪切套筒的旋转转速和剪切应力场段的温度对体系分子取向的影响。结果表明,剪切拉伸双向复合应力场挤管装置中剪切套筒旋转转速的有效形成可有效促进PE-HD/PP/SGF体系分子的取向,改善体系分子的取向度,但随着该转速的加快和该装置剪切应力场段温度的升高,PE-HD/PP/SGF体系分子的取向改善逐渐变弱,而解取向效应变得更加严重。     

Mechanical and rheological properties,and morphology of polyamide-6/organoclay/elastomer nanocomposites

The effects of ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) terpolymer and three types of organoclays (Cloisite^® 15A, 25A, and 30B) on mechanical and rheological properties, and morphology of impact modified polyamide-6/montmorillonite ternary nanocomposites were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), parallel disk rheometry, melt flow index measurements, and tensile and impact tests. The materials were prepared by melt blending using a co-rotating twin-screw extruder. XRD and TEM analyses showed that exfoliated-intercalated nanocomposites were formed in both polyamide-6/Cloisite^® 25A and Cloisite^® 30B binary nanocomposites and in ternary systems. SEM micrographs showed that rubber domain sizes were larger in the nanocomposites than in their corresponding polyamide-6/elastomer blends. Generally, tensile strength, Young's modulus, and elongation at break decreased with the addition of elastomer to polyamide-6/organoclay binary nanocomposites. In the melt state, liquid-like behavior of polyamide-6 slightly turned to pseudo solid-like in the binary and ternary nanocomposites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012