Calculation of the Absolute Breaking Load of Twisted Polypropylene Film Fibres

The Belitsin equation cannot be used for calculation of the breaking load of twisted PP film fibres of different linear density as a function of the twist value because of the large difference from the real breaking load. New coefficients of the change in the breaking load as a function of the twist value and twist coefficient for corrugated PP film fibres with a linear density of 55, 115, and 230 tex are derived using a single-factor experiment design; it can be used to calculate the breaking load with a minimum error. A universal coefficient for the change in the breaking load as a function of the twist value and linear density is obtained for 55-230 tex PP film fibres, and the difference between the real and theoretical breaking load does not exceed 4% as a result of using it.     

Polydisperse Brush with the Linear Density Profile

Macromolecules densely end-grafted to a planar solid surface form a polymer monolayer (brush). It is known that, in a good solvent, the density profile of monodisperse brushes parabolically decays on moving away from the plane. Using the analytical theory and computer simulation methods, we studied the structure of a polydisperse brush from homopolymers, for which molecular-mass distribution is set by the Schulz–Zimm distribution. It is found that, at a polydispersity index of 1.143, the polymer brush in a good solvent has a linear density profile. In this brush, the average distance of chain ends to the grafting plane is proportional to the square of their contour length. If any chain of the brush is chemically modified so that it will be able to adsorb on the grafting surface, then the adsorption of this chain inside the brush will proceed via a discontinuous first-order phase transition with the bimodal distribution of the order parameter (free end height). This transition has unusual features: the energy of adsorption corresponding to the midpoint of the transition is proportional to the contour length of the adsorbing chain N, the sharpness of the transition is proportional to N², and the height of the barrier separating adsorbed and desorbed states is proportional to N³. The predicted dependences are verified by computer simulation.     

利用高密度聚乙烯装置生产线型低密度聚乙烯的相关研究

随着我国经济实力的飞速发展,对线型低密度聚乙烯的需求也有了很大的提升,相关部门必须对高密度聚乙烯装置生产线型低密度聚乙烯工艺给予足够的重视,并且加大对催化剂的研究力度。因此,主要对高密度聚乙烯装置生产线型低密度聚乙烯工艺进行了简要分析,阐述了相关催化系统,并且对生产工艺装置与主要生产流程进行了研究分析。     

线性低密度聚乙烯的稳定性

本文阐述薄膜厚度、共混比例、熔体指数、稳定剂对LLDPE及LLDPE／LDPE共混物薄膜的光老化性、热稳定性和加工稳定性的影响。     

线性低密度聚乙烯抗静电性能研究

考虑到抗静电剂的析出因素,采用非离子型抗静电剂作为线性低密度聚乙烯(LLDPE)试验的主要助剂.研究了抗静电剂C在LLDPE中的析出速度和用量.结果表明:抗静电剂C质量分数不大于0.20%时,LLDPE短期和长期保持了较低的表面电阻率.     

国内线性低密度聚乙烯现状

综述了国内线性低密度聚乙烯市场应用、生产情况、消费状况及技术进展情况,并提出了以后的发展建议。     

非电解质水溶液的密度计算

根据对非电解质水溶液密度实验数据的分析,考虑组分的临界参数和溶液中氢键的影响,导出了二元和多元非电解质水溶液密度的关联式。利用本文关联式计算了7个二元水溶液体系440个数据点的密度,总平均相对误差0．515％;计算了5个三元水溶液体系194个数据点的密度,总平均相对误差为0．405％。计算准确性优于Campbell等人的关联式。使用本模型可由手册查到的纯物质的临界参数和密度等数据,预测非电解质水溶液的密度。     

茂金属线形低密度聚乙烯的热降解研究

研究了光敏剂钴化合物存在时茂金属催化剂和Ziegler—Natta催化剂生产的线形低密度聚乙烯(m—PE-LLD和PE—LLD)的热降解行为，测定了降解后产品的熔体流动速率、红外光谱和氧化诱导温度。结果表明：光敏剂使得加工过程中的降解反应增强，氧化诱导温度降低，氧化曲线形状发生改变；与PE—LLD相比，光敏剂对增强m—PE—LLD的降解反应和降低加工后样品的热稳定性的作用更强。     

Crystallinity of Linear Low Density Polyethylene and of Blends with High Density Polyethylene

Blends of linear low density and high density polyethylene are examined by x-ray diffraction and differential scanning calorimetry in order to characterise the crystalline morphology and to investigate the compatibility of the polymers. The polymers are found to form a co-crystalline phase under a variety of conditions, and can thus be regarded as compatible. The lamellar distributions obtained from the differential scanning calorimetry melting thermograms are found to be dominated by the presence of the high density polyethylene, and this is attributed to the higher mobility of the high density molecules. The lattice parameters of the crystalline phases are found to increase with increasing side branch content.     

线型低密度聚乙烯的改性研究进展

综述了近几年线型低密度聚乙烯(LLDPE)的改性在力学、阻燃、电学、结晶等性能上取得的研究进展,并对未来LLDPE改性的研究方向进行了展望。     

线型低密度聚乙烯抗静电母料的研究

研制了具有协同效应的复合抗静电剂配方,母料中抗静电剂含量为10%以上;使用该母料的专用料加工过程中不仅母料用量可减少,而且产品的加工工艺稳定;专用料的力学性能稳定。能使专用料表面电阻率(ρS)长短期都达到较低值的母粒用量为3.9%。     

线性低密度聚乙烯超微薄膜的加工和应用

介绍了线性低密度聚乙烯超微薄膜的加工技术和应用情况。     

改性蛋白土填充线型低密度聚乙烯的研究

对超细加工并经硅烷偶联剂处理的蛋白土填充线型低密度聚乙烯进行了研究,结果表明:采用适当的偶联剂及恰当的添加量,改性蛋白土可以降低塑料的成本。     

二溴新戊二醇在膨胀型阻燃PE-LLD中的作用

以二溴新戊二醇(DBNPG)作为碳源代替部分季戊四醇(PER), 以PER/DBNPG混合磷酸酯三聚氰胺甲醛树脂(MFR)微胶囊化聚磷酸铵(APP)合成膨胀型阻燃剂(IFR), 用于线形低密度聚乙烯(PE-LLD)阻燃。结果表明,适量的DBNPG可增强IFR与PE-LLD之间的相容性,改善材料的拉伸性能,提高材料熔体黏度,形成封闭的膨胀炭层;但DBNPG过量,IFR的软化温度降低,导致熔体黏度下降,破坏炭层的封闭性,恶化阻燃性能;当PER/DBNPG的质量比为70.0/115.5, 且PE-LLD/IFR的配比为70/30时,复合材料的阻燃性能达到最佳。     

铕配合物对线形低密度聚乙烯老化性能的影响

合成了组成为Eu2·(BA)3·(PhEN)2·nH2O的铕、苯甲酰丙酮和1,10-二氮杂菲三元配合物。利用热重分析仪、热氧老化箱以及自然曝晒、氙灯加速老化实验,并通过考察不同氧化过程中材料力学性能和红外光谱的变化, 研究了此配合物加入线形低密度聚乙烯(PE-LLD)后对其热氧老化、光氧老化及总的老化性能的影响。研究表明,该铕配合物对PE-LLD的光氧化过程有明显的阻滞作用,而对其热氧化过程则有加速作用,对材料老化性能总的影响取决于二者的综合。     

容器内两种互不相溶液体各自密度的计算方法

介绍一种利用安装在被测容器上的双法兰智能差压变送器和就地液位计,通过在实际的工作温度和压力下所测得的容器内两种互不相溶液体间的实际界位,以及与之相对应的变送器正负压室间的压差,利用液柱压强公式建立实际界位与变送器正负压室间的压差关系式,通过两组关系式计算出被测容器内两种互不相溶液体的各自密度的方法。     

线性低密度聚乙烯—炭黑复合物的正温度效应

本文研究了炭黑填充线性低密度聚乙烯复合物的导电性与炭黑含量的关系，PTC强度与CB含量的关系，探讨了未交联与交联复合的PTC效应的热重复性和NTC效应。