高密度聚乙烯制备工艺及应用研究

针对高密度聚乙烯的发展情况,分别从气相聚合法、淤浆法以及溶液聚合法探讨了高密度聚乙烯制备工艺的技术,并论述了典型公司的高密度聚乙烯生产工艺的对比分析,最后结合高密度聚乙烯的生产情况重点探讨了其相应的主要应用情况,以全面提升高密度聚乙烯制备水平.     

高密度聚乙烯HD5070EA的开发应用

盘锦乙烯工业公司根据用户需要，在引进的基础上，通过技术改造设计开发出高密度聚乙烯新产品ＨＤ５０７０ＥＡ。采取了一些技术措施，调整聚合工艺条件──按程序控制注入预聚物次数，控制反应压力为２±０．１ＭＰａ，反应温度８８±２℃，物料粒度增至７００μｍ。产品质量上乘，分子量分布宽，密度范围大，制品物理机械性能优良，是较好的注塑级高密度聚乙烯，质量指标达到当代国际水平。     

高密度聚乙烯缠绕增强管的应用

介绍了高密度聚乙烯（HDPE）缠绕增强管的种类，性能，生产工艺及特点等。因HDPE缠绕增强管具有输水量大，铺设简便等优点，可适用于远距离低压输水，城市给排水，海水输送，以及农田灌溉等输送工程。举例阐述了使用HDPE缠绕增强管的优化，并展望了HDPE缠绕增强管的发展前景。     

导电高密度聚乙烯的研制

通常塑料具有较高的电阻率,有较好的电绝缘性,被广泛用作绝缘材料。但塑料在生产、运输、使用过程会中产生静电,使产品易于吸尘,不易成型加工,还可能因塑料静电而引起燃烧和爆炸事故。随着科学技术的迅速发展,电子产品几乎都是由大规模和超大规模集成电路制造而成,这些电子产品所用的都是微电流,容易发生由于外界电磁波干扰而造成的错误动作、图像障碍等故障。选用金属外壳可以达到电磁屏蔽的要求,但太笨重。为了达到电子仪器设备外壳轻型化,大多采用塑料件。而塑料本身不具备电磁波屏蔽的功能。因此发展导电高分子材料具有非常重要的意义,有非常广阔的应用前景。     

高密度聚乙烯管材拓展新应用

日前,扬子石油化工股份有限公司(简称扬子石化)高密度聚乙烯(HDPE)管材在江苏省盐城市盐城沿海化工园污水处理管道项目招标中,一     

高密度聚乙烯管道应用实例

德国的Harz山脉位于萨克森州（Lower Saxony)的南部，这个山脉也是一个饮用水的来源。六座大水库为Gngen,Braunschweig,Hildesheim,Wolfsburg,Hannover和Bremen等城市提供了必需的饮水资源和工业水，因此保护水资源成为该地方的首要任务。     

硅烷交联高密度聚乙烯的研究

采用了两步法研究硅烷交联聚乙烯,通过实验研究了交联剂对硅烷交联聚乙烯拉伸强度、断裂伸长率及凝胶含量的影响及催化剂对交联反应速度的影响,同时对硅烷交联反应机理进行了探讨。     

高密度聚乙烯阻燃性能的研究

研究了含卤阻燃剂、无机阻燃剂、稳定剂、氯化聚乙烯和不同分子量的基础树脂对高密度聚乙烯的阻燃性和力学性能的影响。     

A closer look into the behavior of oxygen plasma-treated high-density polyethylene

X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure investigation have been used to characterize the surfaces of two oxygen plasma-treated high-density polyethylene (HDPE) samples having different crystalline fractions. Both the observations indicate that a higher degree of crystallinity restricts the mobility of the polar functional groups on the HDPE surface. An increased crystalline order lowers the amount of oxidation and the aging of polar functional groups on the substrate surface. The results are supported by contact angle measurements and field emission scanning electron microscopic observations.     

An investigation of chemical crosslinking effect on properties of high-density polyethylene

High-density polyethylene (HDPE) was chemically crosslinked with various amounts of di-tert butyl cumyl peroxide (BCUP). Crosslink density determined by rubber elasticity theory using hot set test showed an increase with increasing BCUP. Glass transition temperature (T_g), thermal stability, crystallization, melting behavior and tensile properties were studied. The results showed a new finding about decrease in T_g as a consequence of the ‘chemical crosslinking’ of HDPE. This was explained by observed reduction in crystallinity and expected increase in free volume as a result of restriction in chain packing. However, chemical crosslinking had no significant effect on the thermal stability. The stress at break, Young's modulus yield strength and elongation at break generally decreased with increase in BCUP. By increasing the temperature for slightly crosslinked HDPE, the elongation at break was increased but by increasing the crosslinking level an opposite effect was observed. Crosslinked HDPE showed an decrease in creep strain and an increase in creep modulus with increasing BCUP.     

Correlated electrical conductivity and mechanical property analysis of high-density polyethylene filled with graphite and carbon fiber

The development of conductive polymer composites remains an important endeavor in light of growing energy concerns. In the present work, graphite (G), carbon fiber (CF) and G/CF mixtures are added to high-density polyethylene (HDPE) to discern if mixed fillers afford appreciable advantages over single fillers. The effects of filler type and composition on electrical conductivity, composite morphology and mechanical properties have been examined and correlated to establish structure-property relationships. The threshold loading levels required for G and CF to achieve measurable conductivity in HDPE have been identified. Addition of CF to HDPE/G composites is found to increase the conductivity relative to that of HDPE/G composites at the same filler concentration. This observed increase depends on CF length and becomes more pronounced at and beyond the threshold loading of the HDPE/G composite. Scanning electron microscopy is employed to elucidate the morphology of these multicomponent composites, whereas dynamic mechanical analysis reveals that filler concentration, composition and CF length impact both the magnitude and temperature dependence of the dynamic storage modulus.     

High-density polyethylene membranes embedded with carboxylated and polyethylene glycol-grafted nanodiamond to be used in membrane bioreactors

In this work, neat and modified nanodiamond (ND) particles were embedded into high-density polyethylene (HDPE) membranes to improve hydrophilicity and antifouling properties. The membranes were prepared via thermally induced phase separation (TIPS) method and used for pharmaceutical wastewater treatment in membrane bioreactors (MBR) system. To prevent the agglomeration of ND, it was modified using two methods: thermal carboxylation (ND-COOH) and grafting with polyethylene glycol (ND-PEG). Membranes with different concentration of ND-COOH and ND-PEG nanoparticles ranging from 0.00 to 1.00 wt % were prepared and characterized using a set of analyses including water contact angle, pure water flux, tensile strength, differential scanning calorimeter, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. It was found that the optimum contents of ND-COOH and ND-PEG nanoparticles were 0.50 wt % and 0.75 wt %, respectively. The interfacial interaction between nanoparticles and HDPE matrix was studied based on Pukanzsky model. To examine the performance of membranes, critical flux, filtration experiment in the MBR, and fouling analysis of membranes were carried out. The results showed that among the fabricated membranes, 0.75 wt % HDPE/ND-PEG membrane had the highest water flux and the best antifouling properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47914.     

废弃天然纤维增强高密度聚乙烯复合材料性能研究

选用纺织工业废弃苎麻落麻纤维和造纸工业废弃的竹屑纤维为增强体,采用双螺杆熔融共混挤出工艺,制备天然纤维增强高密度聚乙烯（PE-HD）复合材料。考察纤维种类、含量变化对天然纤维增强复合材料熔体流动速率、微观断面形貌、拉伸性能、弯曲性能的影响。结果表明,2种废弃纤维都能有效提高PE-HD的拉伸性能和弯曲性能,其中苎麻落麻纤维的增强效果优于竹屑纤维,加入20% 苎麻落纤维复合材料拉伸强度比纯PE-HD提高21%,弯曲强度提高了41.9%。     

Morphology of high-density polyethylene pipes stored under hydrostatic pressure at elevated temperature

The morphology of unimodal and bimodal high-density polyethylene (HDPE) pipes during a hydrostatic pressure test was studied in detail using ¹H solid-state NMR. Characterizing the changes of the molecular network during such a test is of key importance for understanding the long-term properties of different HDPE pipe grades. The changes in amount, thickness, and molecular mobility of the crystalline phase, the interface, and the amorphous phase of the two pipe grades with the storage time have been quantified for the first time. The most sensitive microscopic parameter to storage is the molecular mobility of the amorphous phase, with the strongest changes shown by the unimodal HDPE. The density of the tie-molecules is not the main factor controlling the very different behavior of the two pipe grades, but rather it is the density of the entanglements. The NMR results offer unprecedented insights into the changes in the molecular network and support existing deformation models.     

硼纤维及其复合材料的研究及应用

从硼纤维的基本性质及与其他纤维性能上的比较等方面,综述了复合材料增强机理和硼纤维增强复合材料的性能特点,并简述了硼纤维增强复合材料的应用领域,对其在未来的发展和应用进行了展望。     

Kinematics of the stick-slip capillary flow of high-density polyethylene

A study of the kinematics of the stick-slip capillary flow of high-density polyethylene has been carried out in this work by using particle image velocimetry (PIV). The experiments covered a wide range of shear rates and the velocity maps and profiles across the die were obtained for the different regimes of the discontinuous flow curve. In the low shear rate region, the melt exhibited shear thinning without slip. In the unstable stick-slip regime, an alternating behavior between full adhesion and slip was observed, whereas both, the maximum velocity and the slip velocity of the melt, changed continuously during pressure oscillations. In addition, non-homogenous slip, characterized by regions with and without slip at the die wall, was occasionally observed during the oscillations. In contrast to the general assumption, the flow in the high shear rate region was found to be unstable, and characterized by high frequency pressure oscillations. A steep rise of the slip velocity took place from the onset of the stick-slip regime and reached values higher than 70% of the maximum velocity for the profiles in the high shear rate branch. However, a true plug flow was never observed due to shear thinning of the melt. Finally, a direct proof of the Mooney hypothesis to account for slip in polymer melts is given on the basis of the comparison of velocity profiles measured in the low and high shear branch.     

高密度聚乙烯/硅烷偶联剂改性硫酸钙晶须复合材料的制备与性能

以γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）改性的硫酸钙晶须（CSW）为高密度聚乙烯（HDPE）的填料,采用熔融共混法制备了HDPE/CSW复合材料。通过SEM、XRD、TG、DSC表征了KH570改性的CSW对复合材料HDPE/CSW的性能影响。结果表明,改性CSW质量分数为20%时,HDPE/CSW的拉伸和弯曲强度比纯HDPE分别增加9.28%和33.04%,且易产生异相结晶,提升了HDPE/CSW复合材料的耐热性和结晶度。纯HDPE的热降解反应活化能为244.11 k J/mol,改性CSW质量分数为50%时,HDPE/CSW复合材料的热降解反应活化能降到236.99 kJ/mol,表明CSW提升了HDPE/CSW复合材料的热降解反应速率,扩展了复合材料的使用范围。     

超高分子量聚乙烯的应用及改性研究进展

介绍了超高分子量聚乙烯（UHMWPE）的性能和用途,综述了提高UHMWPE加工性能和物理性能的物理改性、化学改性、聚合物填充改性以及白增强改性方法的研究进展。指出了其今后的发展方向。