聚乙烯在复合应力场中临界状态挤出成型的研究

采用具有复合应力场的双向拉伸挤出口模，在临界状态下成功制备了聚乙烯双向自增强片材。研究表明，制备的增强片材的纵横向力学性能均有明显提高，维卡软化点提高了21℃。微观测试表明，其晶态结构为串晶，正是由于片材内部生成了大量的串晶结构，才赋予了增强片材比较好的力学性能。     

大口径HDPE双壁波纹管专用树脂的性能研究

对大口径高密度聚乙烯（HDPE）双壁波纹管专用树脂QHE16A／B的力学性能、加工性能、熔体强度等进行了研究。结果表明：QHE16A／B的弯曲模量在1150MPa以上;熔体强度在1．60MPa以上;200℃氧化诱导期在100min左右;具有良好的加工性能;可满足国内生产大口径双壁波纹管的要求。     

埋地排水管用HDPE的研制

根据欧洲标准,结合材料的应用性能及高密度聚乙烯（HDPE）埋地排水管不同结构壁管的成型要求,确定了6360M攻关技术指标。从制品的成型性及材料的宏观性能对树脂的微观结构要求人手,在综合考虑HDPE埋地排水管成型中的流变学、攻关技术指标要求及管材专用树脂的结构特点等基础上开发了新产品6360M。     

HDPE燃气管专用料6380 MBL的性能

研究了高密度聚乙烯(HDPE)燃气管专用料6380 MBL的性能,尤其是长期静液压最小要求强度(MRS)、耐快速裂纹扩展(RCP)、耐慢速裂纹增长(SCG)和耐气体组分。对该专用料的质量认证结果表明:MRS为8 MPa,RCP的小尺寸稳态试验的临界压力大于0.85 MPa,SCG大于或等于500 h,耐气体组分时间大于或等于20 h。6380 MBL符合ISO 4437:2001和GB/T 15558.1—2003的性能要求,并且RCP、SCG性能优良。     

HDPE焊接三通管件壁厚数值优化设计

输气焊接HDPE三通管道,由于焊接使材料性能下降,并产生应力集中,因此必须对管道连接处增加壁厚.基于对HDPE材料性能和焊接处HDPE材料拉伸强度的试验,对HDPE材料三通管道壁厚进行数值优化设计.有限元模型中采用理想弹塑性和Ramberg-Osgood两种材料本构模型,计算得到管道等应力线以及壁厚优化曲线,对管道设计具有实际意义.     

复合应力场下挤出HDPE增强管材性能的研究

用自行研制的能产生先剪切后拉伸的复合应力场挤出成型装置，挤出高密度聚乙烯（HDPE）管材，对管材周向、轴向力学性能进行了初步的研究。与一般牌号为DGDA6098的HDPE比，在HDPE中添加高相对分子质量高密度聚乙烯（HMWHDPE）后，发现HMWHDPE能够诱导HDPE沿应力场方向产生大分子取向和结晶。利用差示扫描量热仪（DSC）和扫描电镜（SEM）检测手段对试样的凝聚态结构进行分析，证实了复合应力场下制备的自增强管材双向力学性能都提高了。     

Crystallization behavior and molecular orientation of high density polyethylene parts prepared by gas‐assisted injection molding

The dependence of hierarchy in crystalline structures and molecular orientations of high density polyethylene parts with different molecular weights molded by gas‐assisted injection molding (GAIM) was intensively examined by scanning electron microscopy, two‐dimensional wide‐angle X‐ray scattering as well as dynamic rheological measurements. The non‐isothermal crystallization kinetics of the samples were also analyzed with a differential scanning calorimeter at various scanning rates. It was found that oriented lamellar structure, shish‐kebab and common spherulites were formed in different regions of the GAIM samples. The scanning electron microscope observations were consistent with the two‐dimensional wide‐angle X‐ray scattering results and showed that the molecular chains near the mold wall had strong orientation behavior, revealing the distribution of the shear rate of the GAIM process. The differences in crystal morphologies can be attributed to molecular weight differences as well as their responses to the external fields during the GAIM process. The formation mechanism of the shish‐kebab structure under the flow field of GAIM was also explored. Copyright © 2012 Society of Chemical Industry     

HDPE埋地排水管专用树脂的工业开发

根据国家标准、欧洲标准中对高密度聚乙烯(HDPE)埋地排水管材专用树脂的要求,确定了产品的质量控制指标和生产工艺参数。在HDPE淤浆法工艺生产装置上,开发了具有优良的物理性能、加工性能和耐环境应力开裂(ESCR)性能的埋地排水管材专用树脂6360M。6360M屈服拉伸强度大于25 MPa;弯曲模量大于1200MPa;ESCR(F50)在1000 h以上;通过了耐内压性能测试。     

HDPE超大口径双壁波纹管专用树脂的设计

针对超大口径双壁波纹管的特定性能设计了高密度聚乙烯(HDPE)专用树脂7800M,并进行了产品质量认证.设计7800M的重均分子量为(3.0～4.5)×105,相对分子质量分布为双峰模式,分布值为40～60;共聚单体选用1-丁烯,且分布在高相对分子质量级分.质量认证结果表明:7800M设计合理,产品实现了高刚性与优异的耐环境应力开裂(ESCR)性能的合理均衡,其弯曲模量在1 400 MPa以上,ESCR(F50)在1 000h以上,可满足超大尺寸管材制品对材料的要求.性能指标符合GB/T 19472.1-2004中对埋地排水管专用树脂的要求.     

管材专用树脂6100 M的加工性能研究

从多种角度对高密度聚乙烯树脂6100M的加工性能进行了研究，得出了最佳加工工艺条件。推荐6100M用于管材制品的最佳加工工艺条件为：机筒180～210℃，机头200～210℃，模头200～220℃，熔体温度200～220℃。北京燕化石油化工股份有限公司生产的6100M加工性能优良，可用于制作直径从小于10cm到2m的各类规格的管材。     

Self‐reinforcement of high‐density polyethylene/low‐density polyethylene prepared by oscillating packing injection molding under low pressure

This article reports the toughness improvement of high‐density polyethylene (HDPE) by low‐density polyethylene (LDPE) in oscillating packing injection molding, whereas tensile strength and modulus are greatly enhanced by oscillating packing at the same time. Compared with self‐reinforced pure HDPE, the tensile strength of HDPE/LDPE (80/20 wt %) keeps at the same level, and toughness increases. Multilayer structure on the fracture surface of self‐reinforced HDPE/LDPE specimens can be observed by scanning electron microscope. The central layer of the fracture surface breaks in a ductile manner, whereas the break of shear layer is somewhat brittle. The strength and modulus increase is due to the high orientation of macromolecules along the flow direction, refined crystallization, and shish‐kebab crystals. Differential scanning calorimetry and wide‐angle X‐ray diffraction find cocrystallization occurs between HDPE and LDPE. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 799–804, 1999     

曲率对PE管材环向拉伸强度的影响

选用环向拉伸试验的方法对高密度聚乙烯（PE-HD）管材环向拉伸的强度进行检测,主要研究拉伸试样在试验进行过程之中曲率的改变对环向拉伸强度的影响,整个试验过程采取多个平行试样进行试验,用以取得准确的试验数据来确定试验结果,并就曲率对PE-HD管材环向拉伸强度影响的变化规律进行研究探讨。结果表明,同一外径的PE-HD管材,随着环向拉伸试样在试验中曲率的减小,环向拉伸强度数值减少可达10 %。     

高密度聚乙烯的壁面滑移行为

用双筒毛细管流变仪和旋转流变仪研究了两种牌号的高密度聚乙烯(HDPE)熔体的壁滑行为,考察了发生壁滑的临界剪切应力。通过剪切速率扫描的方法发现两种牌号的HDPE熔体在较高的剪切速率下均发生粘滑转变,在150～230℃温度范围内,HDPE发生粘滑转变的临界剪切应力位于0.20～0.38 MPa范围内,与文献报道值一致;而且发生粘滑转变的临界剪切应力随温度线性增加,这与B rochard和de Gennes提出壁滑的解缠机理一致。用壁滑外推长度表征壁滑程度,发现两种牌号的HDPE熔体的壁滑外推长度均处于0.05～0.09 mm范围内。     

Morphologies and mechanical properties of HDPE induced by small amount of high‐molecular‐weight polyolefin and shear stress produced by dynamic packing injection molding

To better understand the effect of a small amount of high‐molecular‐weight polyethylene (HMWPE) on the mechanical properties and crystal morphology under the shear stress field, the dynamic packing injection molding (DPIM) was used to prepare the oriented pure polyethylene and its blends with 4% HMWPE. The experiment substantiated that the further improvement of tensile strength along the flow direction (MD) of high‐density polyethylene (HDPE)/HMWPE samples was achieved, whereas the tensile strength along the transverse direction (TD) still substantially exceeded that of conventional molding. Tensile strength in both flow and TDs were highly enhanced, with improvements from 23 to 76 MPa in MD and from 23 to 31 MPa in TD, besides the toughness was highly improved. So, the samples of HDPE/HMWPE transformed from high strength and brittleness to high strength and toughness. The obtained samples were characterized via SEM and TEM. For HDPE/HMWPE, the lamellae of the one shish‐kebab in the oriented region may be stretched into other shish‐kebab structures, and one lamella enjoys two shish or even more. This unique crystal morphology could lead to no yielding and necking phenomena in the stress–strain curves of HDPE/HMWPE samples by DPIM. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Extension of the orientation region of high density polyethylene molded by gas‐assisted injection molding: control of the thermal field

Wider zones with close‐knit orientation crystals in high density polyethylene (HDPE) parts prepared via the gas‐assisted injection molding (GAIM) process were obtained under high cooling gas pressure. In this study, compressed nitrogen, as a cooling medium, was introduced to retain a high cooling rate of the polymer melt. The high gas pressure leads to fast cooling of the polymer melt, which contributes to the stability of more oriented and stretched chains during the cooling stage. Then many more oriented structures are formed. SEM shows that many more oriented structures and interlocking shish‐kebab structures are achieved in parts under highest cooling gas pressure (P3). The P3 parts possess a higher degree of orientation than the corresponding regions of parts under lowest cooling gas pressure (P1). Moreover, tensile testing indicates that, compared with P1 parts, although P3 parts have lower crystallinity, the mechanical properties are improved because of the wider orientation zone and many more interlocking shish‐kebab structures. Combining the HDPE molecular parameters with the characteristics of the GAIM flow field and temperature field, the stability of oriented or stretched chains and the formation of orientation structures in various zones of the parts were analyzed. © 2014 Society of Chemical Industry     

管材专用料HDPE4803T加工性能的研究

在对管材专用料高密度聚乙烯(HDPE)4803T的性能测试和结构表征的基础上,研究了管材加工温度和挤出速度对加工参数的影响情况,并对管材的性能进行了测试.结果表明,HDPE4803T属典型的双峰分布聚乙烯树脂,其性能满足PE80级管材料的指标要求.材料的熔体强度对加工温度变化的敏感性较弱.挤出温度和挤出速度对管材的性能影响很小,采用该管材专用料,可以在较宽的挤出温度和挤出速度范围内制备出性能优良的管材.     

Improved compatibility of PET/HDPE blend by using GMA grafted thermoplastic elastomer

ABSTRACT

Herein, graft-modified ethylene-1-octene copolymer (POE-g-GMA) and styrene-butadiene-styrene triblock copolymer (SBS-g-GMA) were found to be excellent reactive compatibilizers for immiscible poly(ethylene terephthalate) (PET)/high-density polyethylene (HDPE) blends via in-situ reaction compatibilization. With increase in compatibilizer amount, uniform phase morphology was observed in all the blends. Thus, exhibiting enhanced mechanical properties, especially, the notched Izod impact strength. In comparison with SBS-g-GMA, compatibilizer POE-g-GMA demonstrated greater impact on the compatibility. The addition of 15% POE-g-GMA produced blends with best mechanical properties. Besides, both POE-g-GMA and SBS-g-GMA enhanced the melt viscosity of PET/HDPE blends.     

聚合级HDPE通信电缆绝缘料的开发

介绍了齐鲁石油化工股份有限公司生产的高密度聚乙烯通信电缆绝缘料AHJ－01的开发。QHJ－01经物理机械性能和介电性能检测,满足邮电部《市内通信电缆用聚烯烃绝缘料》（YD／T760－95）的要求,并经过多家电缆生产厂的应用表明：QHJ－01与目前国际上较佳的绝缘料产品的综合性能相当。     

The massive formation of hybrid shish‐kebab structures in HDPE/PA6 microfibril blend subjected to melt second flow

During the melt second flow process, the synergetic effect of intense shear and polyamide 6 (PA6) microfibrils finally results in the massive formation of highly oriented crystalline structures in the entire thickness of high‐density polyethylene (HDPE)/PA6 microfibril blend. Interestingly, not only does the small microfibril induce HDPE crystallization to form typical hybrid shish–kebab structure, but the large microfibril (about 2 μm in diameter) also induces the formation of local hybrid shish–kebab structure. For the small PA6 microfibril, the oriented HDPE chains caused by the intense shear are absorbed on the whole surface of the microfibril and then a complete polymer underlayer is formed. Subsequently, the crystal nuclei appear on the underlayer, and then the other oriented HDPE chains overgrow from the nuclei in the form of folded chains and grow perpendicular to the microfibril. Finally, the typical hybrid shish–kebab structure is formed. While for the large PA6 microfibril, a few HDPE chains can be still absorbed on the microfibril surface due to the high surface energy of PA6. However, the driving force is insufficient to absorb largely oriented HDPE chains to form complete hybrid shish but only local adsorption layer, so the local hybrid structure is formed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45274.     

FRP／塑料复合管道设计新方法：限定环向应变设计准则

根据FRP和塑料的不同技术性能特点,提出适用于FRP/塑料复合管道设计的限定环向应变设计准则。多年的工程实践表明,该设计方法简捷、可靠、实用性强,其安全系数取值更为准确、合理。