DYNAMIC VISCOELASTIC PROPERTIES AND THERMAL-PROPERTIES OF NI POWDER-EPOXY RESIN COMPOSITES

The composite materials containing metal Ni powder of 5-15 mu m in siz e were prepared by use of the matrix epoxy resin of glycidyl amine cro sslinked with bis-4-amino-3-methylcyclohexyl methane and 2,4-diamine 3 ,5-dimethyltoluene. Dynamic viscoelastic properties of the composites at various volume fraction (Phi(p)) of Ni powder have been measured ov er the temperature range from 30 to 300 degrees C, The peak temperatur es in dynamic loss modulus-temperature diagrams of the composite incre ased with increasing Phi(p), although the peak position was abruptly s hifted to lower temperatures in the range of Phi(p) more than 0.245. A t this high concentration of Phi(p), agglomeration of the particles oc curring in the composite lead to reduction of the interaction between Ni particle and epoxy resin. Parallel studies on the thermal conductiv ity (lambda) of the composites materials showed that the value of lamb da at Phi(p) = 0.245 increased by approximately 7 times that of the or iginal epoxy resin. The shape of Ni particles also affected the therma l durabilities of the composites; the rough surface of Ni powder yield s a higher storage modulus of the composite than that of the materials containing the powder with a smooth surface, which had been brought t hrough a ball-milling process. The finding suggested that the increasi ng in specific surface area of the powder improved the thermal durabil ity of the composites as well as their mechanical properties. (C) 1998 John Wiley & Sans, Inc.