结晶分级技术表征PE100级与耐热级管材树脂结构的差异性

通过逐步等温结晶分级技术(SIS)、升温淋洗分级技术(TREF)和连续自成核退火分级技术(SSA)表征了聚乙烯(PE) 100级管材树脂GC100S和耐热级管材树脂4731B结构的差异性.结果表明,4731B和GC100S树脂的熔融温度、结晶温度、结晶度、片晶厚度及共聚单体在主链中的分布状况基本相同,主要区别在于含有共聚单体的聚乙烯分子链的相对含量不同,4731B不含或含有少量共聚单体的聚乙烯分子链的含量比GC100S多.     

管材专用PE-RT的结构与性能

基于典型的、牌号分别为XP9000,SP980,DX800,Hostalen4731B的市售管材专用耐热聚乙烯(PERT),采用凝胶渗透色谱法、差示扫描量热法、核磁共振碳谱等表征了PE-RT的相对分子质量及其分布、熔融结晶行为、热分级行为、共聚单体种类及含量等。结果表明:XP9000,DX800,SP980为中密度聚乙烯,相对分子质量分布较窄,结晶度低于60%;Hostalen4731B为高密度聚乙烯,相对分子质量分布较宽,有超高相对分子质量及厚片晶形成;XP9000和Hostalen4731B的熔体强度较高。     

利安德巴塞尔研发出新型耐热聚乙烯树脂

利安德巴塞尔工业公司推出一款新型耐热聚乙烯树脂Hostalen4731B（PE—RT）该树脂具有卓越的长期抗蠕变性能和热稳定性,因此可应用于管道行业。由于其良好的抗蠕变性,这种树脂可被用于实心和铝合金复合管,其T作压力可达1MPa,并可在高达70℃的环境中正常工作。Hostalen4731B树脂还可以提供良好的加工性能,其高熔体强度可使挤出成型管材具有极佳的尺寸稳定性。Hostalen4731B树脂适用于除北美以外的所有地区。     

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。     

埋地排水管材专用聚丙烯树脂的结构与性能

利用核磁共振波谱仪、凝胶渗透色谱仪、X射线衍射仪、差示扫描量热仪、偏光显微镜及动态流变仪等研究了埋地排水管材专用聚丙烯(PP)树脂与给水管材专用PP树脂的结构与性能.结果表明:与给水管材专用 PP树脂相比,埋地排水管材专用PP树脂具有更高的相对分子质量、适宜的相对分子质量分布、合理的乙烯含量及不同的分子链序列结构.埋地排水管材专用PP树脂的弯曲模量大于1 600 MPa,简支梁缺口冲击强度大于80 kJ/m2,负荷变形温度大于100℃,具有优异的刚韧平衡性能和较高的熔体强度.     

一种高密度PE-RTⅡ型管材树脂分子链结构剖析

采用溶剂梯度分级结合凝胶渗透色谱(GPC)、核磁共振碳谱(13C-NMR)、差示扫描量热仪(DSC)等分析表征方法对利安德巴塞尔公司的高密度耐热聚乙烯管材树脂(PE-RT)4731B的分子链结构及聚集态结构进行了分析。结果表明,该PE-RT的结晶度为63 %,晶片厚度31 nm;相对分子质量呈双峰分布,相对分子质量分布达到18.0,低相对分子质量部分的重均相对分子质量(MW)为4.0×103~3.0×104,高相对分子质量部分的MW为3.0×105~6.0×105;短支链均匀分布于高分子链上,共聚单体含量高于1.25 %;高低相对分子质量组分配比为(50~55)∶(45~50)。     

管材专用耐热聚乙烯树脂的结构与性能

采用凝胶渗透色谱、核磁共振碳谱、差示扫描量热法等分析了牌号分别为4731B,SP980,DX800的进口管材专用耐热聚乙烯(PE-RT)的性能及分子结构、相对分子质量及其分布、共聚单体种类及含量、结晶性能等。结果表明:3个牌号的PE-RT均为中、高密度聚乙烯产品(密度为0.935~0.947 g/cm3),其中,4731B为乙烯与1-丁烯的共聚物,共聚单体含量低于SP980和DX800,相对分子质量分布较宽,结晶度为63%,晶片厚度为39.27 nm,晶粒尺寸较大,说明其具有较好的结晶性能。     

Hostalen双峰和多峰管材料的结构和性能对比分析

利用高温凝胶渗透色谱仪(GPC)、差示扫描量热仪(DSC)和哈克流变仪等分析仪器,对比分析了双峰PE100管材料JHMGC100S和多峰耐热聚乙烯管材料Hostalen 4731B的结构和性能。结果表明,JHMGC100S具有较高的重均相对分子质量和较宽的相对分子质量分布;相对于JHMGC100S而言,Hostalen 4731B的短支链更有效地分布在高分子链上,片晶厚度相对较薄,同时其加工性能略好。     

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。     

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。     

苯乙烯-alt-马来酸酐共聚物的合成及其复鞣填充作用

采用溶液聚合的方法制备了系列相对分子质量(简称分子量,下同)不同的苯乙烯-alt-马来酸酐共聚物(SMA),并通过FTIR、1HNMR、13CNMR对产物结构进行了表征,通过DSC对其热性能进行了分析。考察了分子量大小对其在皮革中复鞣填充作用的影响。结果表明,分子量是影响SMA复鞣填充作用的重要因素,随聚合物分子量的增加,处理革的抗张强度降低、撕裂强度增加、部位差降低率增大。当SMA的Mn为6 620时,处理革的撕裂强度、抗张强度和部位差降低率分别为18.325 N/mm、9.519 N/mm2和7.44%,当SMA的Mn为59 058时,处理革的撕裂强度、抗张强度和部位差率降低率分别为20.577 N/mm、5.539 N/mm2和44.98%。     

“D-optimal experimental design” analysis in preparing optimal polyisobutylene based pressure sensitive adhesives

The aim of this work was to model the mechanical properties of different blends of polyisobutylene (PIB) pressure sensitive adhesives (PSAs) with different molecular weights (36,000, 51,000, 75,000, 400,000, and 1,100,000). The mechanical properties of PSAs are usually described by tack, peel, and shear strength which are strongly depended on the bulk viscoelastic properties of the adhesive system. It is assumed that the blends of high and low molecular weight PIB could affect these properties. According to D-optimal design of Design Expert software, various blends of five different molecular weights of PIB have been selected for study in this investigation. Using manual regression analysis, the quadratic model generated for three responses (tack, peel, and shear) was found to be statistically significant (p < 0.05). It was found that tack increases with decreasing molecular weight. It was also found that the presence of B10 and B12 as low molecular weight polymers and B50 as a high molecular weight polymer in increasing peel strength was more dominant compared with B15 and B100. Furthermore, shear strength was found to increase with an increasing concentration of the low molecular weight PIB, B15. The results have shown that statistical analysis meets theoretical expectations and they suggest desired blends of polymer for different aims.     

PMI-St-AN耐热改性剂的合成及应用

以提高聚氯乙烯(PVC)的耐热性能为目的,用悬浮聚合的方法,合成了N-苯基马来酰亚胺-苯乙烯-丙烯腈三元共聚物型耐热改性剂。通过差热分析、元素分析、凝胶渗透色谱分析等手段对共聚物的玻璃化转变温度、组成及其分布、分子量及其分布进行了表征。初步考察了丙烯腈的加入对N-苯基马来酰亚胺-苯乙烯交替共聚体系共聚合规律的影响。将合成的耐热改性剂用于PVC共混改性,取得了较好的效果。     

Interrelationship of strength and flow characteristics of polystyrene

This study investigated the interrelationship between strength and flow characteristics of general-purpose polystyrene (GPPS) used in injection molding applications. The ease of flow was chosen as a measure of processability and was evaluated using the melt flow rate and capillary rheometer techniques. Of the different strength tests that were examined, flexural and notched tensile strength tests were most effective in differentiating between commercial grades of high and low molecular weight GPPS. While characterizing strength of injection molded specimens, the degree of molecular orientation was taken into consideration. For unplasticized resins, increasing the weight average molecular weight by about 100,000 enhanced the flexural strength by 10%, but also increased the viscosity at low shear rates (10 to 100 s^?1). The increase in molecular weight had virtually no effect on viscosity at the highest shear rates (up to 10,000 s^?1). Plasticized resins displayed a 6% loss in flexural strength as well as a significant reduction in viscosity (throughout the shear rate range) as compared with the unplasticized resins. As expected, the improvement in strength achieved by increasing molecular weight leads to a simultaneous increase in the viscosity, i.e., a deterioration of processability. In addition, our study indicates that for samples without preferential molecular orientation, narrowing the molecular weight distribution significantly improves the balance of strength and melt flow rate properties.     

Kinetic and molecular weight control for methyl methacrylate semibatch polymerization. II. Open control

The gel effect will bring a violent increase of conversion for methyl methacrylate (MMA) polymerization in a short time. It will be very dangerous for the reactor, as it causes an increase of molecular weight and broadens the molecular weight distribution. To unify the kinetics, molecular weight, and its distribution, on the basis of the mathematical models for semibatch polymerization of MMA, three controlled objectives that are the heat load distribution index, the change in molecular weight, and molecular weight distribution index are presented. Three materials (monomer, solvent, and chain transfer agent) and their flow rate and feeding mode are analyzed for the open control of kinetics, molecular weight, and its distribution. The optimum flow rate and mode are obtained. The heat load distribution index and molecular weight distribution index are even less than 2.0 and 2.2, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4399–4405, 2006     

Eigenschaftskennfunktionen thermisch hergestellter polystyrole unterschiedlichen molekulargewichts und unterschiedlicher molekulargewichtsverteilung

Mechanical properties and melt flow behaviour have been measured on thermal polystyrenes in order to study the effect of different molecular weight and different molecular weight distribution. The mechanical properties (impact strength, tensile strength and flexural strength) were found to depend upon a critical molecular weight M_w = 1.5 × 10⁵, where the polystyrenes reached ultimate strength. An influence of molecular weight distribution only can be observed when the average molecular weight is near the critical molecular weight limit. The broader the distribution, the poorer are mechanical properties. Injection molded specimens with different molecular weight distribution but equal average molecular weight showed different molecular orientation and different anisotropic mechanical properties. On the basis of equal orientation the narrow distributed specimens showed higher mechanical strength in direction of orientation. The broader the distribution, the higher the elastic properties of melt. An optimum of physical properties and ease of fabrication will be obtained with narrow molecular weight distributed polystyrenes with an average molecular weight slightly above the critical molecular weight limit.     

制备宽/双峰分子量分布聚乙烯的催化体系

利用茂金属加合物和1种Ziegler-Natta(Z-N)催化剂的混合催化体系,制备宽/双峰分子量分布的聚乙烯.考察混合催化体系中茂金属加合物和Z-N催化剂的配比对聚合物分子量、分子量分布以及结构性能的影响.     

浇注型端羟基聚丁二烯聚氨酯弹性体的合成及性能研究

采用不同分子量的端羟基聚丁二烯（ＨＴＰＢ）和甲苯二异氰酸酯为主要原料合成预聚物，以Ｎ，Ｎ－Ｍ（２－羟丙基）苯胺为扩链剂制备了浇注型聚氨酯弹性体，并着重研究了预聚体中游离异氰酸酯基含量、扩链剂用量、ＨＴＰＢ分子量以及不同分子量ＨＴＰＢ并用和扩链剂并用对弹性体力学性能的影响，还对弹性体的结构与形态进行了初步分析和探讨。结果表明，预聚体中游离异氰酸酯基含量为９．０％时，拉伸强度最大，且综合性能最佳；扩链系数为０．８９时，拉伸强度、定伸应力、硬度出现最大值；ＨＴＰＢ分子量增大，弹性体力学性能有下降趋势，不同分子量ＨＴＰＢ并用时分子量大的ＨＴＰＢ增多，力学性能下降；当ＨＴＰＢＭｎ＝３１００，游离异氰酸酯基含量为９．０％，扩链系数为０．８９时，弹性体综合性能最佳。电子显微镜照片显示ＨＴＰＢ型聚氨酯有微相分离，且软硬键段分布不规整。     

氢化丙烯酸松香/丙烯酸酯复合乳液的制备及其压敏胶的性能

以氢化丙烯酸松香为增黏树脂,将其溶解在丙烯酸酯单体中,预乳化后采用半连续乳液聚合工艺制备了氢化丙烯酸松香/丙烯酸酯复合乳液。研究了氢化丙烯酸松香的用量对单体转化率、凝胶率、溶胶相对分子质量及其分布、乳胶膜的玻璃化温度(Tg)和压敏胶粘接性能等的影响。结果表明,氢化丙烯酸松香对单体聚合具有一定的阻聚作用,随着氢化丙烯酸松香用量的增加,单体转化率、凝胶率及相对分子质量下降,相对分子质量分布变窄。氢化丙烯酸松香的合适用量为8.0%wt,此时压敏胶的初黏力为15#,180°剥离强度为10.6N.25mm-1,持黏力大于120h。