İLETKEN KATKI MADDELERLE TAKVİYE EDİLMİŞ POLİMER KOMPOZİTLERİN TERMOFİZİKSEL ÖZELLİKLERİ

Yükseköğretim Kurumları Destekli Proje, BAP Araştırma Projesi, 2013 - 2014

Proje Türü: Yükseköğretim Kurumları Destekli Proje
Destek Programı: BAP Araştırma Projesi
Başlama Tarihi: Ekim 2013
Bitiş Tarihi: Aralık 2014

Proje Özeti

In this study, thermal conductivity of aluminum particles reinforced high density polyethylene composites has been examined experimentally, numerically and theoretically. High density polyethylene-aluminum composite materials have been produced by using mold compression process in various (1, 2, 4, 6, 8, 10, 12, 15, 18, 21, 25, 30 percent) volumetric concentrations of aluminum.

Thermal conductivity of polymer composites has been measured by C-Therm thermal analyzer depending on the modified transient plane source technique. Thermal conductivity of high density polyethylene-aluminum composite materials increases by increasing volume fraction of aluminum particles.

Numerical study is carried out as functions of concentrations, arrangements and geometries of filler materials in two and three dimensional by ANSYS 14.0 based on finite element analysis software. For two dimensional analyses, shapes of filler are selected as cylinder and square prism, shape of matrix is chosen square prism. For three dimensional analysis, shape of matrix is selected as cube and filler materials’ shapes are simulated sphere and cube. Effect of changing amount of fillers in the matrix is examined that the fillers number in the matrix is assumed to be as 1, 2, 4, 8 and 16. As shape of aluminum particles are assumed to be spherical, sphere filler models are found to be in good correlation with experimental values.

Experimental measured thermal conductivity values have been compared with theoretically calculated ones. Maxwell’s, Hamilton & Crosser’s, Meredith & Tobias’s, Lord Rayleigh’s, Agari & Uno’s, Lewis & Nielsen’s theoretical models are found to be closer to experimental values.

The specific heat of selected High density polyethylene-aluminum composite was obtained by diamond differential scanning calorimeter (Perkin Elmer Precisely, U.S.A). Specific heat capacity increases by increase in temperature for both neat high density polyethylene and high density polyethylene-aluminum nanocomposites. A decrease in the specific heat was observed with addition of aluminum to high density polyethylene. A significant increase in the enthalpy of melting of addition of aluminum to high density polyethylene up to 1 percentage. After this volume fraction, the aluminum incorporation decreases the enthalpy of melting by the reason of reduced crystallinity along with change in polymer phase morphology. The aluminum powders and high density polyethylene-aluminium composites’ morphological analysis were conducted with Philips XL 30S FE SEM. The shapes of aluminum powder (40-80 µm) particles have more irregular than that of aluminum powder (80 nm) particles. The aluminum powder particles (80 nm) dispersed more uniformly in the high density polyethylene matrix, despite local agglomerations have been seem. For both size of aluminum powder particles, as loading level of aluminum raises, the frequency of agglomeration increases. Increasing volume fraction of aluminum in the composites, increasing voids in the composites.

Keywords: Thermal conductivity, polymer composites, theoretical thermal conductivity model, ANSY, specific heat, morphological