聚丙烯/纳米黏土复合材料抗熔垂性能的研究

在双螺杆挤出机上制备了聚丙烯/纳米黏土复合材料;考察了其结构对其抗熔垂性能的影响。X射线衍射分析结果表明,实验得到了插层结构聚丙烯/纳米黏土复合材料,不同的聚丙烯基体和相容剂用量影响材料的插层结构。抗熔垂性能研究发现,不同的插层结构,抗熔垂性能不同。其中,黏土片层插层结构的层间距与材料抗熔垂性能存在一定关联,插层结构中黏土片层层间距过大或过小都不利于抗熔垂性能的改善,层间距为2.90-3.00 nm的插层结构的聚丙烯/纳米黏土复合材料具有较好的抗熔垂性能。     

辐照改性聚丙烯抗熔垂能力的研究

采用熔垂测试仪测量了不同配方辐照改性聚丙烯（PP）的抗熔垂能力，分析了温度、敏化剂含量、辐照剂量和高相对分子质量物质等因素对PP抗熔垂能力的影响，提出了PP辐照过程中长支链的形成机理，解释了PP抗熔垂能力随辐照剂量变化的规律。结果表明，辐照改性能显著提高PP的抗熔垂能力，PP的抗熔垂能力随温度的升高而降低，并随敏化剂含量的增加而提高，在辐照过程中加入极少量高相对分子质量物质能有效提高PP的抗熔垂能力；辐照改性的PP可在较宽的温度范围内表现出较强的抗熔垂能力，有利于发泡、热成型等。     

大中空聚乙烯专用料DMDZ6149性能研究

研究了600 000 t/a全密度聚乙烯装置生产大中空聚乙烯专用料DMDZ6149的基础物性、链结构、热性能及加工性能,并与市售原料进行对比。结果表明:相较于2种市售原料,DMDZ6149具备更加优异的刚韧平衡性和耐环境应力开裂性能,抗熔垂性能和加工范围与市售原料相当。     

大口径低熔垂管材专用料开发和加工应用

介绍了中国石油吉林石化公司PE100级大口径低熔垂管材专用料JHMGC100S-LS的开发和应用情况。通过优化生产工艺条件,使产品的熔融指数更稳定,拉伸屈服应力、拉伸断裂标称应变、简支梁冲击强度等重要指标不断提升。结果表明,JHMGC100S-LS的抗熔垂性能良好,生产出的产品外观良好,能够满足大口径管材生产需要。     

PE100级管材专用树脂的结构和性能

对两种采用不同工艺生产的PE100级管材专用树脂(分别记作树脂A和树脂B)进行了结构剖析和管材加工性能评价。结果表明:与树脂A相比,树脂B的共聚单体含量少,重均分子量大,相对分子质量分布略窄,结晶度高,零剪切黏度高,熔体强度大;相同加工温度条件下,树脂A的加工流动性好,树脂B的抗熔垂性好;两种树脂所制管材的静液压强度、耐慢速裂纹增长性能与耐快速裂纹扩展性能均满足国家标准要求。     

高熔体强度聚丙烯树脂的结构与性能

采用差示扫描量热法、傅里叶变换红外光谱、毛细管流变、熔体拉伸等方法,从结晶性、黏弹性及物理机械性能等方面对高熔体强度聚丙烯(HMSPP)树脂进行结构表征与性能分析。结果表明:HMSPP树脂具备较高的弯曲模量,同时具备优异的抗熔垂能力和更宽的加工温度;拉伸黏度随拉伸速率的增大而增大,呈现出HMSPP应变硬化这一明显行为,使得熔体在热成型过程中具有均匀变形的自我调节能力,从而克服普通聚丙烯在热成型加工中的严重熔垂问题;含有较长接枝链段的HMSPP树脂在刚性、熔体强度、结晶性能等方面均优于普通聚丙烯。     

三聚氰胺氰尿酸阻燃尼龙6的抗熔滴燃烧性研究

考察传统抗滴落剂聚四氟乙烯（PTFE）微粉和氮磷复合型阻燃剂三聚氰胺磷酸盐（MP）对三聚氰胺氰尿酸（MCA）阻燃尼龙6抗熔滴燃烧性的影响。结果表明,PTFE与MCA之间有对抗效应,加入PTFE后材料的阻燃性能有所降低;而MP可显著增强其凝聚相过程,有效降低材料的熔滴燃烧性,提高材料的阻燃性能。     

沙特基础新型HDPE降低客户成本

<正>沙特基础工业公司推出一种应用于典型压力管的高密度聚乙烯(HDPE)材料——Vestolen A Rely,这种材料可缩短生产周期、节省大量能源。目前该材料有两种级别,均适于生产PE100标准的压力管。Vestolen A Rely 5924R表现出优异的低熔垂性能,适于生产大口径、低标准尺寸比率的压力管道。     

双峰PE100级管材专用树脂的结构与性能北大核心

采用差示扫描量热法分析、核磁共振碳谱、连续自成核退火热分级、高压毛细管流变、旋转流变等研究了国内外三种PE100级管材专用双峰(即相对分子质量分布呈双峰)聚乙烯(PE)的结构与性能。结果表明:三种双峰PE片晶厚度分布指数接近,易形成较厚片晶;属于假塑性流体,剪切黏度对剪切速率变化敏感;熔体强度高,抗熔垂性能好,适宜高速挤出成型,制作大口径、尺寸稳定性产品。PE100级管材专用树脂P6006熔体强度和零剪切黏度较高,推断P6006相对分子质量高,且高相对分子质量部分含量高;3490LS剪切黏度对剪切速率变化最敏感,剪切变稀明显;3490LS相对分子质量分布较宽,具有较好的加工性能。     

抗熔垂结构性粘合剂

一种可在塑料、复合物和金属上作用更快并产生很强的抗剥离键的新型丙烯酸粘合剂已由美国康涅狄格州落基山的Henkel Loctite公司研制成功．这种抗熔垂粘合剂商品名为Speedbonder H8000．是由100％反应性双组分凝胶体构成．可     

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。     

Synthesis,characterization, and properties of silicone–epoxy resins

Silicone–epoxy (SiE) resins were synthesized through the hydrolytic condensation of 2‐(3,4‐epoxycyclohexylethyl) methyldiethoxysilane (EMDS) and the cohydrolytic condensation of EMDS with dimethyldiethoxysilane. Structural characterization was carried out by ¹H‐NMR, ²⁹Si‐NMR, and mass spectrometry analysis; the resins were linear oligomers bearing different numbers of pendant epoxy groups, and the average number of repeat Si O units ranged from 6 to 11. Methyhexahydrophthalic anhydride was used to cure the SiE resins to give glassy materials with high optical clarity. The cured SiE resins showed better thermal stability and higher thermal and UV resistances than a commercial light‐emitting diode package material (an epoxy resin named CEL‐2021P). The effect of the epoxy value on the thermal and mechanical properties and the thermal and UV aging performances of the cured SiE resins were investigated. The SiE resins became more flexible with decreasing epoxy value, and the resin with the moderate epoxy value had the highest thermal and UV resistances. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

水杨醛亚胺镍配合物在甲苯中催化乙烯聚合

研究了水杨醛亚胺中性镍配合物在甲苯中催化乙烯聚合。在膦捕捉剂乙酰丙酮乙烯基铑[Rh(acac) (C_2H_4)_2]存在下,聚合活性和聚乙烯(PE)的相对分子质量均随乙烯压力的升高呈递增趋势,但随聚合温度升高而降低。由双(1,5-环辛二烯)合镍[Ni(COD)_2]作助催化剂,乙烯聚合的活性较高,但所得PE的相对分子质量、熔点和结晶度较低。动态流变研究表明,助催化剂可增加PE的支化度和降低其相对分子质量,以提高其高温加工性能。核磁共振氢谱、碳谱和广角X射线衍射研究表明,不同助催化剂所得PE的结构类似,而支化度分别为每1000个C中8和16个支链。     

NMR Molecular Dynamic and Thermal Analysis Studies of Amescla Resin

Two polyethylene (PE) samples (named BF and ES) were blended with 5% organoclay by melt processing at different shear rates. X-ray diffraction (XRD) showed that the organoclay was incorporated into the PE matrices. From the results it was determined that the level of intercalation was very similar for both systems. The knowledge of molecular dynamics of PE nanocomposites is very important since it depends on the clay dispersion. Thus, the objective of this work was to employ a new technique to understand changes in the molecular mobility for these systems. The samples were characterized by proton nuclear spin-lattice relaxation time (T₁H), which is measured in a low-field NMR spectrometer. The influence of the samples' preparation was evaluated through the relaxation data. For polyethylene resins, two values of relaxation parameter were found and they were attributed to mobile region (low value) and rigid region (high value). These values change after nanocomposite formation, confirming the changes in the resin matrix after organoclay was incorporated.     

PE100级管材树脂结构和性能研究

通过凝胶渗透色谱(GPC)、熔体质量流动速率(MFR)、差示扫描量热(DSC)、力学性能和流变仪等分析手段,研究了国产PE100树脂的结构和加工性能。研究结果表明,3种PE100树脂结构接近,JH-MGC100S具有良好的耐热老化性能和力学性能。在240℃时JHMGC100S的加工性能好于其它2种样品。     

聚乙烯管材专用树脂生产技术开发

利用淤浆法串联聚合丁艺产品具有相对分子质量双峰分布的特点,结合管材专用树脂的物性及微观结构特点,确定了由第一聚合釜均聚合生产低相对分子质量产品、第二聚合釜共聚合生产高相对分子质量产品的生产工艺。通过对2个聚合釜聚合温度、聚合压力、共聚单体的加入量和氢气与乙烯比等工艺参数的分析和调整．得到适合高级别管材专用树脂的最佳生产条件,产品的最小要求强度超过8MPa,达到管材专用树脂PE80的等级。     

Effect of rotation extrusion and molecular weight on ductile failure of polyethylene pipes under hydrostatic pressure

ABSTRACT

In this study, two kinds of polyethylene (PE) with different molecular weight were processed into the pipes via rotation extrusion and the failure behaviours under hydrostatic pressure as well as molecular relaxation were investigated. The experimental results showed that the high molecular weight PE exhibited slower relaxation behaviour with higher relaxation activation energy to facilitate the formation of shish-kebab under flow field, while for the low molecular weight one, the stretching molecules easily relaxed back coil state and spherulites were prone to form. Therefore, the low molecular weight PE pipes via convention and rotation extrusions had similar isotropic spherulite morphology and short failure times. In the case of high molecular weight PE, during the convention extrusion, polymer melts flowed along the axial direction to induce the alignment of shish-kebab accordingly, which went against to the hoop stress in hydrostatic pressure. With the rotation of mandrel and die, the direction deviated from the axis so that PE pipe exhibited better resistance to the hoop stress. The failure time was 182?h, 264% longer than the convention-extruded one. Accordingly, a new strategy to prepare high hydrostatic pressure PE pipe under cooperative effects of rotation extrusion and long molecular relaxation time was proposed.     

PE100级管材专用树脂性能研究

分析了高密度聚乙烯(HDPE)管材专用树脂DGDB 2480H及典型双峰PE 100级管材专用树脂的性能。两者的力学性能相当;DGDB 2480H具有较低的剪切黏度,有利于管材的加工成型,熔体强度为1.05 MPa,与国产及进口管材专用树脂相当,比普通HDPE大,有利于大口径管材的挤出。     

Oxygen permeation resistance of polyethylene,polyethylene/ethylene vinyl alcohol copolymer,polyethylene/modified ethylene vinyl alcohol copolymer,and polyethylene/modified polyamide–ethylene vinyl alcohol copolymer bottles

The oxygen permeation resistance of polyethylene (PE), polyethylene/ethylene vinyl alcohol copolymer (PE/EVOH), polyethylene/modified ethylene vinyl alcohol copolymer (PE/MEVOH), and polyethylene/modified polyamide–ethylene vinyl alcohol copolymer (PE/MPAEVOH) bottles was investigated. The oxygen permeation resistance improved significantly after the blending of ethylene vinyl alcohol copolymer (EVOH) barrier resins in PE matrices during blow molding; less demarcated EVOH laminas were found on the fracture surfaces of the PE/EVOH bottles. Surprisingly, the oxygen permeation resistance of the PE/MEVOH bottles decreased significantly, although more clearly defined modified ethylene vinyl alcohol copolymer (MEVOH) laminas were found for the PE/MEVOH bottles as the compatibilizer precursor contents present in the MEVOH resins increased. In contrast, after the blending of modified polyamide (MPA) in EVOH resins, more demarcated modified polyamide–ethylene vinyl alcohol copolymer (MPAEVOH) laminar structures were observed in the PE/MPAEVOH bottles as the MPA contents present in the MPAEVOH resins increased. In fact, with proper MPAEVOH compositions, the oxygen permeation resistance of the PE/MPAEVOH bottles was even better than that of the PE/EVOH bottles. These interesting oxygen barrier and morphological properties of the PE, PE/EVOH, PE/MEVOH, and PE/MPAEVOH bottles were investigated in terms of the free volumes, barrier properties, and molecular interactions in the amorphous‐phase structures of the barrier resins present in their corresponding bottles. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2528–2537, 2004