ABSTRACT:The influence of untreated glass beads (GB) and Aerosil (A), as well as glass beads treated with aminosilanes (GBA) on the melting behavior of nylon 6 was studied with the aid of differential scanning calorimeter (DSC-I). It was found that glass beads with low surface energy (GBA) exerted no appreciable influence on the melting characteristics of a polymer, while in filled samples of the GB and A series, heats of crystallization and melting linearly decreased with a total solid surface area, the slope being numerically equal to the heat of the wetting of A by nylon 6 melt. Equilibrium melting temperature in the samples of these series abruptly dropped from 511 K to 499 K after interparticle separation decreased below about x= 10 x 10-6 m, and remained thereafter approximately constant at Tm 0 =501±3K down to x=50xl0-6 m. At x=30xl0-6 m, no crystallization was observed above 440 K, and the melting temperature of this sample when cooled to room temperature was independent of the crystallization temperature in the range below 440 K. Annealing of these samples at 300 K resulted in the appearance of relaxation endotherms on the heat capacity curvtJs above the glass-transition interval, the strength of said endotherms smoothly increasing with the filler content. The experimental data were discussed in terms of changes in the initial melt structure of nylon ·6 and competition between surface forces tending to increase the filler coverage and opposing its bulk driving force for polymer crystallization tending to pull segments from filler surface onto growing crystal face.KEY WORDS Crystallization/ Heat Capacity/ Melting Behavior/ Nylon 6 / Filler / Inter Particle Separation / Incorporation of inorganic fillers into organicpolymer matrixes was originally for the purpose of acheiving optimum mechanical properties in the resulting composites by combining the high modulus and strength of the fomer with the elasticity of the latter. However, it was found that not only mechanical but also many other static and dynamic properties of filled polymers invariably failed to obey the simple linear rule of mixtures, the magnitude (and in some cases even the sign) of the deviations from additivity being strongly dependent both on the chemical nature of components, as well as on their relative content. 1 -8 These manifestations of the "long-range" nature of the solid-surface effect on polymer structure and properties were attributed to the formation of boundary-polymer layers with changed properties as a result of a complex interplay of energetic and entropic phenomena involved in the polymer~filler interactions. 9 The applicability of this concept, which has proved successful for interpreting the bulk properties of filled amorphous polymers, 10 -14 in the case of filled crystallizable polymers was, however, tested only on a relatively modest scale, 15 -17 since so far the main attention of polymer scientists has been directed toward investigating crystal-nucleation phenomena in polymer melts containing very small amounts of ...