调控分子链制备的双峰聚乙烯的分子量分布及性能

采用高密度聚乙烯(HDPE)5000S和自制的分子链调控聚乙烯(CMPE)熔融共混得到一系列分子量分布具有双峰特征的聚乙烯共混物。采用凝胶渗透色谱仪(GPC)测定了共混物的分子量分布(MWD)曲线,并研究了共混物材料的拉伸、冲击及断裂韧性等力学性能及加工性能。研究表明,CMPE的MWD曲线的峰位置显著向低分子量方向移动,便于用来制备双峰聚乙烯。加入CMPE有利于显著提高材料的加工流动性,且当CMPE的质量分数在20%以下时,材料的拉伸强度、冲击强度以及断裂韧性等力学性能均维持在较高的水平,不出现明显的降低。     

分子量及其分布对聚丙烯力学性能和结晶行为的影响

通过机械共混的方法制备一系列不同分子量及其分布的聚丙烯，并对其力学性能和结晶行为进行了表征，研究了分子量及其分布对这些性能的影响以及力学性能和结晶行为的对应关系。通过实验发现，分子量及其分布对聚丙烯的结晶速率，结晶温度，结晶度，冲击强度，拉伸屈服强度，断裂伸长率等均有较大影响。     

SEBS增容等规聚丙烯/间规聚苯乙烯共混体系的结构与性能

用3种组成相近而分子量不同的苯乙烯-乙烯/丁烯-苯乙烯共聚物(SEBS)作为增容剂,对等规聚丙烯/间规聚苯乙烯(iPP/sPS)共混物进行增容。研究了共聚物的分子量对iPP/sPS共混物的形态结构及力学性能的影响。结果表明,中、低分子量的SEBS具有较好的增容作用,能有效提高共混物的拉伸强度;而高分子量的SEBS则能显著改善共混物的韧性。用SEM观察了增容剂在共混物中的分布情况,揭示了共混物的力学性能不仅取决于增容剂的界面活性,而且还与增容剂在共混物中的分布密切相关。     

HMW—HDPE与LMW—HDPE的共混改性

选用一种高分子量高密度聚乙烯（ＨＭＷ－ＨＤＰＥ）和一种低分子量高密度聚乙烯（ＬＭＷ－ＨＤＰＥ），对它们的共混行为和共混物的热性能、流动性能和力学性能进行了研究。结果表明，在研究的共混比范围内，由ＤＳＣ发现双组分体系可能存在共晶相。ＨＭＷ－ＨＤＰＥ／ＬＭＷ－＝ＨＤＰＥ共混体系的熔体指数基本符合Ａｒｒｈｅｎｉｕｓ粘度加和方程：ＭＩ＝ＭＩ．ＭＩ２。在ＬＭＷ－ＨＤＰＥ质量百分含量为２０％时，共混体系的拉伸     

低分子量无规聚丙烯与商用聚丙烯复合材料的紫外荧光性能

通过将分子量无规聚丙烯（LMWAPP）与商用等规聚丙烯（IPP）共混,研究其发光性能,结果表明,低分子量无规聚丙烯对聚丙烯的发光起着重要作用,着聚丙烯中LMWAPP含量的增加,聚丙烯发光强度增加,当LMWAPP含量超过30％时,发光强度达到饱和。     

大型中空容器级HDPE料的性能研究

采用两段淤浆聚合工艺合成了具有双峰／宽峰相对分子质量分布（MWD）的高密度聚乙烯大型中空容器级树脂,并对共混物树脂的力学性能、流变学行为进行了分析表征。力学性能结果表明,随着丁烯-1含量的增加,共混物的密度、熔点减少,环境应力开裂（ESCRF50）增加,而共混树脂的刚性很大程度上取决于可获得到的结晶度。国产树脂样的数均相对分子质量和重均相对分子质量很大,刚性较高,MWD呈宽峰分布,而ESCRF50都偏低。流变学行为结果表明,通过调整氢气、改变共聚单体的加量,控制低相对分子质量均聚物／高相对分子质量共聚物的质量分数,可以获得力学性能和加工性能的平衡。     

调控分子链制备的双峰聚乙烯的结晶行为及晶体结构

采用熔融共混的方法将高密度聚乙烯(HDPE)5000S与自制的分子链调控聚乙烯(CMPE)共混制备得到了一系列分子量分布(MWD)不同的双峰聚乙烯(BPE)共混物。对共混物进行普通DSC、连续自成核退火热分级技术(SSA)、等温结晶等一系列测试。结果表明,CMPE的加入有利于提高5000S的结晶能力,能加快其结晶速度,并在一定程度上完善其晶体结构。同时在CMPE含量适当时,共混物厚晶片的厚度和厚晶片含量不会发生显著的降低。     

微注射成型高密度聚乙烯-线性低密度聚乙烯共混物的微结构及力学性能

为提高线性低密度聚乙烯（LLDPE）的拉伸强度和模量,扩大其应用领域,将三种不同相对分子质量的高密度聚乙烯（HDPE）分别与LLDPE共混,通过微注射成型技术制备HDPE-LLDPE制品。综合利用DSC、广角X射线衍射（WAXD）、小角X射线散射（SAXS）和拉伸性能测试研究了共混物在微注射成型过程中的结构演化及力学性能。拉伸测试结果表明,与纯LLDPE相比,HDPE-LLDPE的拉伸强度和模量随HDPE分子量的增加而增加。微结构分析结果显示,随HDPE分子量的增加,HDPE-LLDPE制品的分子链和片晶取向度增大、结晶度增加,且制品内形成了较多取向的Shish-Kebab晶体结构。通过分析微结构的表征结果,解释了HDPE-LLDPE的拉伸强度和模量显著提高的原因。     

LLDPE及VLDPE对LDPE／HDPE共混物拉伸性能的影响

研究了线性低密度聚乙烯（ＬＬＤＰＥ）和极低密度聚乙烯（ＶＬＤＰＥ）对高密度聚乙烯（ＨＤＰＥ）／低密度聚乙烯（ＬＤＰＥ）共混物拉伸性能的影响。由于ＬＬＤＰＥ或ＶＬＤＰＥ的加入，改善了ＨＤＰＥ与ＬＤＰＥ间的相互作用，提高了ＨＤＰＥ／ＬＤＰＥ共混物的拉伸性能。     

MPE/LLDPE/LDPE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），线性低密度聚乙烯（LLDPE）及高压聚乙烯（20％固定质量配比的LDPE）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，熔体粘度和膨胀比的影响，为MPE的共混改性加工提供了理论依据，不同共混比的熔体均为假塑性流体，共混熔体的假塑性随LDPE／LLDPE的增多而增强，共混熔体的转变应力和非牛顿指数随LDPE／LLDPE的增加而降低，对加工的敏感性提高，加工性能得到改善。     

PC改性HDPE共混体系的组成对拉伸性能的影响

本工作旨在通过共混改性实现聚烯烃塑料高性能化。介绍了高密度聚乙烯／聚碳酸酯共混体系中组成对拉伸性能及形态的影响。结果表明，随ＰＣ含量增加，共混物的拉伸强度增加，断裂伸长率降低，而加入１０ｐｈｒ的增容剂烯基双酚Ａ醚接枝ＬＤＰＥ的体系，在相同ＰＣ含量时，其拉伸强度和断裂伸长率均高于未加增容剂的体系；ＰＣ含量低时，体系中ＰＣ基本上呈圆球状，ＰＣ含量较高时，部分ＰＣ粒子为形成椭球状、长条状，甚至纤维状；共     

热空气老化对LDPE/POE共混物结晶行为和力学性能的影响

在70℃条件下,对低密度聚乙烯(LDPE)/聚烯烃弹性体(POE)共混物进行八周热空气老化试验,通过差示扫描量热法(DSC)和宽角X射线衍射(WAXD)表征了共混物结晶行为的变化,研究了热空气老化对共混物力学性能的影响。w(POE)为30%的共混物具有优异的耐热氧老化性能,在老化前期,其断裂伸长率有所增加,在老化后期才略有下降,而拉伸强度则基本不变。热空气老化对共混物结晶行为产生明显的影响,且结晶行为的变化主要在老化前期完成。经过热空气老化,部分在制备过程中形成的不完善晶体重新结晶,晶粒尺寸逐渐变大,提高了LDPE结晶的完善性。     

Effect of the processing method on the mechanical properties and morphology of compatibilized PA6/LDPE blends

In this work, the effect of the processing method on the mechanical properties and morphology of compatibilized PA6/LDPE blends was investigated. The blends were prepared by two processing methods: Injection and Extrusion followed by Injection. The compatibilizers used were polyethylene grafted with acrylic acid (PEgAA) and polyethylene grafted with maleic anhydride (PEgMA). The results showed that in both processing methods the impact strength and elongation at break of the compatibilized blends were greater than those of the uncompatibilized ones. For the blends prepared by injection, the impact strength of PA6/PEgMA/LDPE blend was greater than that of PA6/PEgAA/LDPE blend. For the blends prepared by extrusion followed by injection, the impact strength of the PA6/PEgAA/LDPE blend was greater than that of PA6/PEgMA/LDPE blend. SEM analysis showed that the morphology of the PA6/PEgAA/LDPE blend prepared by extrusion followed by injection was more stable than that of the same blend prepared only by injection.     

Phase behaviour, mechanical properties and thermal stability of thermosetting polymer blends of unsaturated polyester resin and poly(ethylene oxide)

The results of dynamic mechanical analysis reveal that crosslinked polyester resin (PER)/poly(ethylene oxide) (PEO) blends show a composition dependent glass transition temperature, Tg, which suggests that the blends studied are homogeneous in the amorphous state. The initial dynamic storage modulus, E', decreases with increasing PEO content up to 30 wt% in the blends, whereas E for both the 60/40 and 40/60 PER/PEO blends is close to that for the 80/20 PER/PEO blend and much larger than that for the 70/30 PER/PEO blend. The addition of crystalline PEO has a remarkable effect on the mechanical properties of crosslinked PER. Tensile testing shows that the elongation at break first increases greatly and then decreases slightly, whereas the Young's modulus and the tensile strength first decrease and then increase slightly with increasing PEO content in the blends. The variation of tensile properties was considered to be due to both the plasticization effect and the crystallization effect of PEO in the blends. The impact strength remains almost unchanged with increasing PEO content in the blends studied. No dramatic decrease of thermal stability for PER/PEO blends was observed for the blends with PEO content up to 30 wt%.     

SEBS-g-MA对R-PET/LLDPE共混物结构与性能的影响

以SEBS-g-MA为相容剂,借助力学性能、DSC、SEM和DMA等表征手段对SEBS-g-MA在R-PET/LLDPE/SEBS-g-MA共混物中的作用进行研究。研究发现,添加质量分数10%的SEBS-g-MA时,共混物的缺口冲击强度和断裂伸长率都得到明显的改善。DSC分析结果表明,LLDPE和PET的熔点都没有发生变化,但PET的熔融峰出现双峰。SEM结果显示,添加10%SEBE-g-MA能够使LLDPE在PET基体中充分分散,过量的SEBS-g-MA会诱导部分PET进入分散相,最终形成Salami结构的聚集体。     

紫外线辐照HDPE与尼龙－6共混材料结构与力学性能的研究

研究了紫外线辐照ＨＤＰＥ与ＰＡ６共混材料的微观形态、结晶结构、熔融行为及力学性能。ＳＥＭ、ＷＡＸＤ、ＤＳＣ结果表明，随紫外线辐照时间的增加，共混物中ＰＡ６的粒径减小，与基体作用加强，ＨＤＰＥ晶面间距增大，熔点、结晶度降低，熔程变窄。力学性能测试结果表明，紫外线辐照能明显提高共混材料（ｕＨＤＰＥ／ＰＡ６：９０／１０）的拉伸强度、断裂伸长率、拉伸断裂能和冲击强度。当辐照时间超过１４４ｈ由于ＨＤＰＥ热稳定性明显降低，共混过程中ＨＤＰＥ热降解严重，共混物的韧性突降。     

Effect of core–shell structured modifier ACR on ASA/SAN/ACR ternary blends

In this study, acrylonitrile–styrene–acrylic terpolymer/styrene–acrylonitrile copolymer/acrylic resin (ASA/SAN/ACR) ternary blends with different compositions were prepared by melting blending. Properties of the ternary blends were studied by differential scanning calorimetry, heat distortion temperature (HDT), Fourier transform infrared (FTIR) spectra, melt flow rate (MFR), mechanical properties, and scanning electron microscopy (SEM). The blends showed two T _gs at about −48 and 109 °C. FTIR analyses showed no strong interactions between the characteristic groups existed in the prepared blends. No obvious phase separation observed in SEM images indicated good compatibility in the blend system. With respect to mechanical properties and processability, the addition of ACR not only led to the improvement of impact strength and elongation at break, but also the decline of tensile strength, flexural properties, hardness, and MFR. Furthermore, heat resistance of ASA/SAN (70/30) binary blends decreased with the addition of ACR, but the HDT of ASA/SAN (30/70) almost remain unchanged.     

In situ polymerization preparation of blends of poly(methyl methacrylate) and poly(styrene-co-acrylonitrile)

The in situ polymerization of methyl methacrylate (MMA) with poly(styrene-co-acrylonitrile) (SAN) was studied. The PMMA/SAN in situ polymerization blends obtained were examined by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), tensile tests and scanning electron microscopy (SEM). The blends with compositions of 95/5, 80/20, 70/30, and 60/40 in weight ratios were miscible and had a single phase structure. However, the 90/10 PMMA/SAN in situ polymerization blend obtained was inhomogeneous and had a two-phase structure; polymerization-induced phase separation occurred during the preparation process of the blend. Both tensile strength and elongation at break increase with increasing SAN content up to 30 wt%. The degradation temperature and thermal stability of PMMA increased remarkably on incorporation of SAN up to 30 wt%.     

Utilization of waste expanded polystyrene: Blends with silica-filled natural rubber

Expanded polystyrene (EPS) constitutes a considerable part of thermoplastic waste in the environment in terms of volume. In this study, this waste material has been utilized for blending with silica-reinforced natural rubber (NR). The NR/EPS (35/5) blends were prepared by melt mixing in a Brabender Plasticorder. Since NR and EPS are incompatible and immiscible a method has been devised to improve compatibility. For this, EPS and NR were initially grafted with maleic anhydride (MA) using dicumyl peroxide (DCP) to give a graft copolymer. Grafting was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy. This grafted blend was subsequently blended with more of NR during mill compounding. Morphological studies using Scanning Electron Microscopy (SEM) showed better dispersion of EPS in the compatibilized blend compared to the noncompatibilized blend. By this technique, the tensile strength, elongation at break, modulus, tear strength, compression set and hardness of the blend were found to be either at par with or better than that of virgin silica filled NR compound. It is also noted that the thermal properties of the blends are equivalent with that of virgin NR. The study establishes the potential of this method for utilising waste EPS.     

聚丁内酰胺的热性能改性

聚丁内酰胺的熔点与热分解温度较接近,不利于熔融加工.文中采用溶液共混法制备支化聚丁内酰胺(B-PA4)及线型聚丁内酰胺(L-PA4)共混物,并通过差示扫描量热分析、X射线衍射和热重分析表征共混物的结晶性能及热性能,通过拉伸测试研究了共混膜的力学性能.结果表明,B-PA4的加入使得共混物的结晶度、熔点、热稳定性均发生降低...