Design and optimization of constituents for conductive polymer nanocomposite

Abstract

In recent years, conductive polymer nanocomposites (CPNC) have attracted the considerable attention from worldwide researchers due to their wide range of applications. Presently, conducting polymer composites are being made with the high volume fraction of reinforcing fine particles as 12-30% [9-12]. In many cases, especially in fibre forming matrix, the highly concentrated conductive filler is resulting deterioration in mechanical properties because of their poor moldability and draw ability [7,13]. As a result, nowadays, a great challenge for the researchers in the field of conductive grade polymer nanocomposites is to minimize (possibly within 6%) the filler concentration with better conductivity.

Present study is designed to develop a conductive polymer nanocomposite of binary matrix of polypropylene (PP) and poly ethylene-co-vinyl acetate (EVA) to reduce the filling load with good thermal conductivity. Moreover, another target is to increase draw ability of the rigid polymer polypropylene (PP) without too much compromise of its tensile strength. The total work was done by taking one organic particle (activated carbon, AC) and one inorganic particle (alumina, Al) as reinforcement. For rigorous analysis, both microparticle and nanoparticle reinforced samples were made through melt compounding method by premixing and hot press. The samples were prepared by mixing individual particle as well as in various ratios of activated carbon and alumina with the PP/EVA matrix. For better understanding of thermal conductivity of the composite and optimize the constituent materials several analytical techniques as tensile, flexural, thermal conductivity, DSC and water absorption tests were conducted. In order to analyze and support the experimental results thus obtained SEM and FTIR were also used.

For all cases, tensile strength of binary matrix (PP/EVA) composite reinforced by binary particle (activated carbon/alumina) has been found higher than that of the binary (PP/EVA) matrix reinforced by single particle (activated carbon or alumina). From experimental result, it is revealed that the individual particle created a problem related to coagulation effect in the matrix, however, in the case of binary particle (activated carbon/alumina) better dispersbility of particle in the matrix has been observed and this has been thought one of the big challenge to achieve better functional properties in the particle reinforced polymer composites. Moreover, in all perspective, nanocomposites show better results than the microcomposites. The %elongation of the developed composite is decreased with the increase in the alumina particles in the binary matrix and this phenomenon has also been found when the particles are used individually in the composite. Here it to be noted that PP/EVA matrix has been selected for composite design to improve the draw ability of the PP. This study found that whatever the particle content the % elongation is always greater than pure PP. Also in binary particle composite, the tensile as well as flexural strength and thermal conductivity increased with the increase in the relative proportion of alumina particle than carbon. The crucial finding in the present research is that the thermal conductivity shows a better result in a certain relative ratio of carbon and alumina, which is 1:4 in PP/EVA matrix. However, the composite containing binary reinforcing particle shows better thermal conductivity in both microcomposite and nanocomposite, where the thermal conductivity of nanocomposite is 23% higher than that of the microcomposite. Also the thermal conductivity of the developed nanocomposite is nearly 13 times higher than that of the pure PP and 10 times of that of the PP based microcomposite.