MICROSTRUCTURE AND STIFFNESS ANALYSIS OF A NEW TERNARY MELAMINE-FORMALDEHYDE COMPOSITE

A new ternary planar random fiber composite manufactured under the nam e RMC (Reinforced Melamine Compound) is studied. Microstructure and st iffness of the random glass fiber-reinforced and particulate-filled me lamine-formaldehyde composite processed by compression molding from RM C molding compounds are analyzed. Glass fiber bundles in a mixture of melamine-formaldehyde resin with various size of filler particulates o utside the bundle space, and small size particulates inside the bundle space are found from scanning electron microscopy (SEM) and optical m icrographs. The tensile modulus of the particulate-filled matrix is mo deled using equations of Halpin and Tsai, and Lewis and Nielsen. The t ensile modulus of the resin/filler/fiber composite is calculated using the Halpin-Tsai equation followed by a randomization procedure employ ing the averaging concept of Nieisen and Chen. Fiber bundles rather th an single fibers are assumed as the reinforcing unit. Parameter xi rep resenting the reinforcing efficiency is discussed for the case of stif fness in the direction transverse to the bundles orientation. Predicte d values of the tensile modulus are in good agreement with experimenta l results for various compositions. Different resin/filler/fiber compo sitions are characterized using the calculated tensile modulus values together with merit indices introduced for the purpose of tailoring th e composite toward minimized weight and material cost.