IBC桶专用HDPE的结构与性能

分析了进口和国产中型散装容器(简称IBC桶)专用高密度聚乙烯(HDPE)的基本性能、毛细管流变性能、动态流变性能。结果表明:采用不同工艺生产的进口HDPE的相对分子质量分布不同,但均较国产HDPE的宽;进口HDPE的支化度较高、耐环境应力开裂性能优异,耐环境应力开裂时间达2 000 h以上,国产HDPE由于支化度较低,耐环境应力开裂时间为840 h;国产HDPE黏度较高、弹性较低;国产HDPE的抗冲击性能较好,尤其是低温抗冲击性能达20 k J/m2,所制IBC桶可以通过低温跌落试验。     

HDPE耐环境应力开裂性能的研究及改进

对HDPE的耐环境应力开裂性能进行了研究。试验表明:采用共混及化学改性的方法,HDPE的耐环境应力开裂性能有了很大提高,为解决HDPE树脂在制作管材时出现的短时间内应力开裂问题提供了依据。     

氯化聚乙烯对高密度聚乙烯耐环境应力开裂性能的改进

本文对HDPE与CPE的共混物进行研究,旨在改进HDPE制品的耐环境应力开裂性能。将不同组成比的HDPE与CPE共混并压片,测试其力学性能、热性能、耐环境应力开裂能力和微观结构。试验发现混入少量CPE即可使HDPE的耐环境应力开裂能力得到改善,除临界含量以外,采用直接共混和二步法共混得到的结果不同。     

聚碳酸酯耐环境应力开裂性能的研究

研究了聚碳酸酯(PC)的耐环境应力开裂(ESCR)行为;探讨了摩尔质量及分布、后处理工艺、温度、溶剂等因素对PC的耐环境应力开裂性能的影响.结果表明:摩尔质量越高,分布越窄,则PC临界应变值越高,耐环境应力开裂性能越好;退火热处理有利于提高PC环境应力开裂性能.此外,温度降低和试样与溶剂溶度参数差Δδ增大均有利于提高PC耐环境应力开裂性能.同时提出了聚合物耐环境应力开裂模型,对环境应力开裂机理进行了探讨.     

管材专用高密度聚乙烯的研究进展

综述了国内高密度聚乙烯(HDPE)的生产装置及工艺。采用双峰聚合工艺使短支链更多地分布在高相对分子质量部分是HDPE管材从PE80级升至PE100级的主要原因。管材的耐环境应力开裂性能随HDPE相对分子质量减小而下降,提高短支链含量可提高管材的耐环境应力开裂性能。HDPE的相对分子质量越高,管材抗裂纹扩展性能越好,将短支链分布在高相对分子质量端可提高抗裂纹扩展性能。     

钛系小中空容器专用HDPE的性能及优化

对比了钛系与铬系小中空专用高密度聚乙烯(HDPE)的力学性能、耐环境应力开裂性能、熔体强度、阻隔性能、相对分子质量及其分布等.结果表明:钛系小中空容器专用HDPE?HD5502TA具有优异的耐环境应力开裂性能、阻隔性能、刚韧平衡性能、食品安全性以及较宽的相对分子质量分布,可替代铬系小中空容器专用树脂应用于食品、药品、日...     

小中空容器专用双峰HDPE HD5503GA的结构与性能

采用高温凝胶色谱仪、高压毛细流变仪、差示扫描量热仪等分析了国内首个小中空容器专用双峰高密度聚乙烯(HDPE)HD5503GA的结构与性能,并与小中空容器专用进口双峰HDPE及国产单峰HDPE进行了比较。结果表明:HD5503GA具有加工性能好、相对分子质量分布宽、耐环境应力开裂性好及刚性强的特点,其耐环境应力开裂时间是国产单峰HDPE的16.00倍,是进口双峰HDPE的1.75倍,刚性较国产单峰HDPE高57%以上,与进口双峰HDPE相当;与国产单峰HDPE相比,可降低加工温度10～20℃,且制品表面致密,印刷性好,HD5503GA的加工性与进口双峰HDPE接近,更适宜于高腐蚀性及高极性液体的包装。     

电缆用聚乙烯复合材料耐环境应力开裂性能影响因素的研究

通过研究添加不同组分的高密度聚乙烯(HDPE)、线型低密度聚乙烯(LLDPE)、乙烯-醋酸乙烯共聚物(EVA)以及不同含量的交联剂过氧化二异丙苯(DCP)对电缆用聚乙烯复合材料的力学性能、耐热性能及耐环境应力开裂性能的影响。发现LLDPE、EVA含量的增加会降低电缆的拉伸强度,提高电缆的断裂伸长率。TG测试发现,DCP的加入可以提高材料的耐热性能。通过环境应力开裂测试发现LLDPE、EVA均可显著提高材料的耐环境应力开裂性能。     

电线电缆用HDPE护套料的研制

采用共混改性的方法,研制了电线电缆用高密度聚乙烯(HDPE)护套料,其配方:HDPE TR144为70.0 phr,HDPE 6084为30.0 phr,高耐磨炭黑为2.7 phr,抗氧剂为0.8 phr,润滑剂为0.7 phr。该护套料的绝缘电阻率为3.48×10~(14)Ω·m,耐环境应力开裂大于500 h,耐气候老化时间4 000 h时;材料的断裂伸长变化率为5%。     

高密度聚乙烯复合管市场分析

1 高密度聚乙烯(HDPE)的重要应用之一——管材的情况 HDPE管材是一个有发展前途的产品。它以优异的化学性能、韧性和耐磨性以及低廉的价格和安装费受到管道界的重视,仅次于聚氯乙烯(PVC)使用量,成为第二位的塑料管道材料。 HDPE可制成波纹管、油气管、煤气管、上下水管、灌溉用管、工业及采矿用管,这些管均要求它具有优良的机械强度,耐压、耐湿、耐环境应力开裂、耐热应力开裂、耐化学品及不易渗透,且质轻,与同样规格、同样强度的普通管相比,可省料40％左右。     

Modeling of the fracture mechanism of HDPE subjected to environmental stress crack resistance test

Environmental stress crack resistance (ESCR) is a commonly used test to characterize cracking failure of high‐density polyethylene in applications such as wires, cables, blow molded containers, and other rigid packaging applications. From a resin design standpoint, it is important to understand the mechanism of environmental stress cracking especially in the case of materials with significantly different ESCR values. Currently, two standard ESCR tests, ASTM D1693 and ASTM F2136, are commonly accepted to measure environmental stress crack resistance of HDPE. An accurate observation of ESC is important to understand the fracture mechanism of samples. In this study, the ESCR performance of six HDPE samples was determined per ASTM D1693. The failed specimens were further characterized by scanning electron microscopy and fractographic methodology to investigate the failure mechanism. HDPE resins with low ESCR values had crack surfaces characterized by shorter and fewer fibrils. A new empirical model to predict polymer ESCR using tie chain concentration with different integration range, and water vapor transmission rate, to characterize detergent diffusion in the crack, was developed. The proposed empirical parameter improves the prediction of ESCR. The ability to predict ESCR performance from resin properties is a beneficial tool for new product development. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Morphological,mechanical, tribological,and thermal expansion properties of organoclay reinforced polyethylene composites

The morphological, mechanical, thermal, and tribological properties of high‐density polyethylene (HDPE) composites reinforced with organo‐modified nanoclay (3 and 6 wt%) were studied. A commercial maleic anhydride‐based polymeric compatibilizer (PEgMA) was used to improve the adhesion between the polyethylene and clay. Transmission electron microscopy (TEM) characterization of composites revealed that nanoclay exists mainly in a multilayered structure in the HDPE matrix. Mechanical testing of composites showed that Young's modulus and tensile strength increased with nanoclay content. Coefficients of the linear thermal expansion (CLTE) of HDPE–PEgMA–clay composites were slightly lower in the flow direction than those of HDPE–PEgMA. The tribological properties were measured in dry conditions against a steel counterface. The friction coefficient of the matrix was decreased by the addition of clay. Electron microscopic results suggested that the wear mechanism for HDPE and HDPE composites was mainly adhesive. Clay agglomerates were observed on the worn surfaces of the composites, which may partly explain decreased friction. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

HDPE/纳米CaCO3复合体系相容机理研究

为探讨HDPE与纳米CaCO3粉体的相容机理,比较研究了表面处理剂-硬脂酸(S)、增容剂(HDPE-g-MAH)的增容机理。采用扫描电镜观察纳米CaCO3粉体在聚合物HDPE基体中的分散和界面作用机理,并建立了HDPE/纳米CaCO3粉体复合体系相容性机理的物理模型。结果表明:加入表面处理剂(S)-增容剂(HDPE-g-MAH)复合界面改性剂后,两相相容性进一步增强。     

ESCA and other morphological investigations of the brittle failure caused by an environmental stress cracking (ESC) of a HDPE milk crate

The causes of a drastic reduction in the service life of a HDPE milk crate have been investigated. The mechanism and the type of crate failure have been deduced from a detailed morphological examination of its fracture surface as well as the interior. Various factors responsible for a rapid failure of the milk crate have been identified. An ESCA study of ESC of weathered milk crate surfaces revealed the presence of heavy oxidative degradation on the surface and a diffusion-controlled oxidation mechanism being operative in successive inner layers. The brittleness of this surface layer and formation of sharp cracks therein have been exhibited in SEM micrographs. Optical micrographs clearly show the presence of a surface layer, formed due to degradation, which is nonspherulitic and thus identifiable from the bulk, which is imperfectly spherulitic. Evidence for a migration of polymer additives from bulk to the surface is provided by the ESCA data and the SEM micrographs. DSC thermogram of the microtomed surface layer reveals bimodal endothermic peaks attributed to two phases present in the surface layer—one original phase and the second being degradation-induced. The formation of this brittle surface layer and its effect on the long-term fracture performance of milk crates are discussed, and suggestions for improving their durability are given.     

HDPE/LLDPE/POE薄膜性能的研究

采用线型低密度聚乙烯（LLDPE）和热塑性弹性体乙烯-辛烯共聚物（POE）对高密度聚乙烯（HDPE）薄膜进行改性,研究了LLDPE和POE对共混体系薄膜力学性能、加工性能的影响,探讨了LLDPE增强HDPE的机理。结果表明,加入一定量LLDPE,使HDPE／LLDPE薄膜的拉伸强度较纯HDPE薄膜有所增加,而单位冲击破损质量则有所下降。当w（LLDPE）为15％时,HDPE／LLDPE薄膜的拉伸强度提高21．6％,薄膜的单位冲击破损质量降低23．0％。在HDPE／LLDPE/POE三元体系中,当w（POE）,w（LLDPE）分别为10％,15％时,薄膜的拉伸强度、单位冲击破损质量、断裂伸长率比纯HDPE薄膜分别提高2．3％,113％。36．0％,综合性能良好。     

抗静电HDPE的研究进展

简述了抗静电HDPE的抗静电机理及其应用领域,介绍了抗静电剂的种类和抗静电HDPE的常用制备方法最后分析了抗静电HDPE的未来发展方向和前景,并对抗静电剂的发展提出了建议     

Crystallization,melting behavior,and morphology of BPP/HDPE blend

The crystallization, melting behavior, and morphology of a low ethylene content block propylene–ethylene copolymer (BPP) and a high-density polyethylene (HDPE) blend were studied. It was found that the existence of ethylene–propylene rubber (EPR) in BPP has more influence on the crystallization of HDPE than on that of PP. This leads to the decreasing of the melting temperature of the HDPE component in the blends. It is suggested that the EPR component in BPP shifted to the HDPE component during the blending process. The crystallinity of the HDPE phase in the blends decreased with increasing BPP content. The morphology of these blends was studied by polarized light microscopy (PLM) and SEM. For a BPP-rich blend, it was observed that the HDPE phase formed particles dispersed in the PP matrix. The amorphous EPR chains may penetrate into HDPE particles to form a transition layer. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 2469–2475, 1998     

Morphology and mechanical properties of styrene–ethylene/butylene–styrene triblock copolymer/high‐density polyethylene composites

The morphology and mechanical properties of a styrene–ethylene/butylene–styrene triblock copolymer (SEBS) incorporated with high‐density polyethylene (HDPE) particles were investigated. The impact strength and tensile strength of the SEBS matrix obviously increased after the incorporation of the HDPE particles. The microstructure of the SEBS/HDPE blends was observed with scanning electron microscopy and polar optical microscopy, which illustrated that the SEBS/HDPE blends were phase‐separation systems. Dynamic mechanical thermal analysis was also employed to characterize the interaction between SEBS and HDPE. The relationship between the morphology and mechanical properties of the SEBS/HDPE blends was discussed, and the toughening mechanism of rigid organic particles was employed to explain the improvement in the mechanical properties of the SEBS/HDPE blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

HDPE/LDPE复合交联物的热降解研究

采用热重分析仪（TG）考察了高密度聚乙烯（HDPE）／低密度聚乙烯（LDPE）复合交联物的热稳定性。结果显示，HDPE／LDPE复合交联物的热稳定性低于HDPE／LDPE共混物。FTIR分析证实，交联反应使聚乙烯（PE）的支化程度提高，取代基的位阻效应在一定程度上影响了PE的热降解过程。在N2气氛下，HDPE／LDPE共混物及交联物的热降解过程均为一步降解反应。Kissinger法求解HDPE／LDPE共混物及其复合交联物的热降解活化能发现，LDPE质量分数在20％～30％之间变化时，HDPE／LDPE交联物的热降解过程对温度的敏感性发生了突变。