Preparation And Properties Of Nylon11/Silanized Silicon Carbide Composites

Nylon11is an engineering plastic.It has excellent physical, chemical andmechanical performance,meanwhile, has characteristics of light weight, corrosionresistance, low water absorption, good dimensional stability, excellent wear resistanceand oil resistance. Therefore, it is widely used in automotive, aerospace, electronics,military industry and other fields.However,with the development of science andtechnology, the applications of simple nylon11has been limited because the impact oftheir performance short board and the high prices. So, it is necessary to prepare thenylon11composites which has high-performance. In this paper, firstly, silicon carbidesurface modified by silane coupling agent (KH550), then，the nylon11/SiC compositeswas prepared by melt blending with the main raw material of nylon11aggregates andmodificated silicon carbide. Secondly, the morphology and composition of compositeswas characterized by scanning electron microscopy(SEM) and fourier-transform infraredspectroscopy(FT-IR), separately, and the crystal morphology was observed by polarizingmicroscope, the crystallization properties and rheological properties of composites wereanalysed by differential scanning calorimeter (DSC) and capillary rheometer, so that themechanical and barrier properties of composite materials was investgated.1. The result from infrared spectrum characterization showd that surfacemodification of silicon carbide was successful by using ilane coupling agent（KH550）;scanning electron microscopy showed that silicon carbide were uniformly dispersed inthe matrix of nylon11, fully polymerization was generated, it is improved tensilestrength, bending strength, impact strength and the elongation of composites wasimproved with the addition of silicon carbide; Compare with pure nylon11, barrierproperties of composites was increased.2. From the study of crystallization and melting behavior of Nylon11/SiC composite materials, we found that silicon carbide played a role of heterogeneousnucleation in composite, and it enhanced the crystallization rate of composites. theAvrami equation is suitable for handling isothermal crystallization kinetics of nylon11and nylon11/SiC composites; the non-isothermal crystallization kinetics of compositescan be deal better through Avrami equation revised by Jeziorny and Mo’s method. Theequilibrium melting point of composite materials was obtained by Hoffman-Weeksformula, and it was found that equilibrium melting point of nylon11/SiC compositeswas lower than pure nylon11.3. From the investigation results of the rheological properties of nylon11and nylon11/SiC composites, we found that non-Newtonian coefficients were all less than1, itmeans that they were all pseudoplastic fluids. With the increasing of the content of SiC,the shear rate first increases and then decreases, while the shear stress was fixed. Withthe increasing of the shear rate, the apparent viscosity of composites was decreasedgradually and exhibited shear-thinning behavior. Comparing with pure nylon11, nylon11/SiC composites had the lower activation energy of viscous flow, it showed that theimpact of the processing temperature on the apparent viscosity became smaller, thus, thecomposites can be processing and molding in a wide temperature range.