乙烯-丙烯嵌段共聚物与高密度聚乙烯熔体相容性的探讨

利用MiniLab微型混合流变仪测定高聚物熔体平衡转矩-转速关系曲线,探讨乙烯-丙烯嵌段共聚物(E-b-P)和高密度聚乙烯(HDPE)的熔体相容性.结果表明:Eb-P/HDPE共混物熔体是完全互容的,HDPE对E-B-P中的PE链段有更大的亲和力,可形成不同的核壳结构,使共混物的平衡转矩偏离原有的加和性,表现出协同效应.     

不相容共混高聚物熔体的平衡转矩-组成关系

选用苯乙烯-丙烯腈共聚物(SAN),高密度聚乙烯(HDPE),聚丙烯(PP)和线性低密度聚乙烯(LLDPE)为样品,利用MiniLab微型混合流变仪,研究了SAN/HDPE,SAN/PP和SAN/LLDPE共混高聚物熔体不相容体系的平衡转矩随组成变化的规律。结果表明:与相容共混体系不同,不相容共混体系的平衡转矩不随组成单调的递增或递减,而呈现水平钝角型或者U型曲线变化。当两纯组分的流动性差异较大时其为水平钝角型曲线,相近时则为U型曲线。     

MiniLab测定高聚物熔体流变曲线准确性的探讨

MiniLab微型混合流变仅可直接测定样品熔融共混后熔体流变曲线,但因缺乏可靠的体积流量与螺杆转速的相关系数,其所得到的流变参数只是相对测量值.通过准确测定高聚物熔体在狭缝流道中的体积流量,校正了体积流量系数,使该仪器的流变参数测量由相对变为绝对,螺杆同向和反向旋转所测得的样品流变曲线经校正后完全重合,与经Bagley校正后的高压毛细管的流变曲线也有很好的重合性.因此,该仪器可用来准确测量高聚物熔体的流变曲线.     

MiniLab测定高聚物熔体流变曲线可靠性的评估分析

MiniLab微型混合流变仪可直接测定样品熔融共混后熔体流变曲线,但可靠性尚未评估.因此,通过实验研究对其进行评估.结果表明:MiniLab具有样品用量少(6 g)、仪器稳定性好、数据重现性好、灵敏度高的特点,但是所得到的流变数据是相对值.     

相容共混物熔体的平衡转矩与组成关系的探讨

以熔体指数不同的高密度聚乙烯(HDPE)和均聚聚丙烯(PP)为试样,利用MiniLab微型混合流变仪,研究了在熔融状态下完全互容的HDPE/HDPE、PP/PP和HDPE/PP共混物熔体的平衡转矩随组成的变化规律。结果表明:相容共混体系的熔体平衡转矩-组成关系曲线一般表现为线性或者二次抛物曲线。当高分子链的化学结构单元不同时,其共混熔体的平衡转矩-组成关系多为二次抛物曲线。     

高聚物熔体平衡转矩-转速关系曲线测定方法的探讨

用Minilab微型混合流变仪对高聚物熔体平衡转矩-转速关系曲线的测定方法进行探讨,实验结果表明:利用该仪器动态变速测试程序可以快速准确地得到物料的平衡转矩-转速关系曲线.     

高聚物熔体平衡转矩-转速关系曲线影响因素的探讨

用Minilab微型混合流变仪研究高聚物熔体平衡转矩-转速关系曲线的各种影响因素.结果表明:加工条件(温度、转速)、物料组成组份、以及添加剂(交联剂、抗氧荆)等影响物料熔体结构和状态的因素,都能在其平衡转矩-转速关系曲线中得到很好地体现,因此可将此关系曲线用于聚合物加工方面的指导.     

PP/EHDPET共混体系熔体粘度对相转变的影响

以聚丙烯 (PP) /易水解聚酯 (EH DPET)共混体系为研究对象 ,测试了共混组分在不同加工温度与不同剪切速率下的熔体粘度。结果表明 ,加工温度与剪切速率的改变均会导致 PP与 EHDPET熔体粘度比的变化 ,进而影响到两组分的海 -岛结构构成。选择较高的加工温度及较低的剪切速率 ,可以使共混物 PP在高组成比时成为分散相。     

PP/EHDPET共混体系相转变研究——熔体弹性的影响

采用熔融共混纺丝的方法 ,以易水解聚酯 (EHDPET)为一组分与 PP经单螺杆共混纺丝制得试样 ,测试了共混组分的流变性能。以 SEM为研究手段 ,通过改变喷丝孔长径比及纺丝温度 ,讨论了熔体弹性对共混纤维相转变的影响规律。加大喷丝孔长径比 ,适当提高纺丝温度有利于使 PP在高组成比时构成分散相     

AN含量对PVC/SAN共混物相容性的影响

采用乳液聚合技术合成了一系列不同丙烯腈（AN）含量的苯乙烯-丙烯腈（SAN）共聚物,将其与聚氯乙烯（PVC）熔融共混,形成PVC/SAN共混物,并引入增塑剂邻苯二甲酸二辛酯（DOP）。通过动态力学分析仪（DMA）和扫描电子显微镜（SEM）对共混物的玻璃化转变温度和相结构进行表征,考察不同AN含量对PVC/SAN共混物相容性的影响。     

Surface Tension of Molten Glass from Drop Profile. Application to the Characterization of the Interface in Glass/Polymer Blends

A modified drop shape method has been developed to allow the simple determination of the surface free energy of a mineral glass. Our approach is based on the study of the profile of a large sessile drop of glass. The drop is formed by heating a glass cylinder settled on a horizontal solid plane.

The experimental parameters, in particular the size of the glass drop, leading to the accurate characterization of the surface free energy, have been determined by using mercury as a model of a high surface free energy liquid. It has been shown that the ratio between the diameter of the drop and the capillary length, (γ/ρμ)^1/2, must be of the order of 10.

In this paper, practical details and results of measurements are presented for a series of four different glasses. A clear relationship between glass composition and surface free energy is observed. In particular, tin oxide reduces significantly the surface free energy of zinc phosphate glass. The coalescence of glass particles is probably related to glass surface and glass/polymer interfacial free energies. A discussion on how this may impact glass/polymer blend processability is presented.     

A review on the mechanical and electrical properties of graphite and modified graphite reinforced polymer composites

Carbon materials particularly in the form of sparkling diamonds have held mankind spellbound for centuries, and in its other forms, like coal and coke continue to serve mankind as a fuel material, like carbon black, carbon fibers, carbon nanofibers and carbon nanotubes meet requirements of reinforcing filler in several applications. All these various forms of carbon are possible because of the element's unique hybridization ability. Graphene (a single two-dimensional layer of carbon atoms bonded together in the hexagonal graphite lattice), the basic building block of graphite, is at the epicenter of present-day materials research because of its high values of Young's modulus, fracture strength, thermal conductivity, specific surface area and fascinating transport phenomena leading to its use in multifarious applications like energy storage materials, liquid crystal devices, mechanical resonators and polymer composites. In this review, we focus on graphite and describe its various modifications for use as modified fillers in polymer matrices for creating polymer-carbon nanocomposites.