Multilayered hybrid roving as a manufacturing concept of continuous fiber–reinforced thermoplastic materials

Abstract

A new manufacturing concept named multilayered hybrid (MLH) roving was invented in the form of a fiber roving separated evenly into several sublayers by thermoplastic films, which is manufactured by the sequential processes of spreading, fixing, and folding. This concept is aimed to combine the variety in processing of commingled roving and the variety in material configuration of organic sheet. For the review on impregnation basics, the Kozeny–Carman equation was examined on the packed bed of fibers, not of particles, to check out the controllable parameter. Also, the newly derived spreading equation was prepared to prevent the current problem of center splitting during fiber spreading processes. The impregnation quality was practically verified by the bending test on the unbalanced (2/1) woven fabric made of polypropylene (PP) and glass fiber (GF) MLH roving, PP/GF45 vol.% (70 wt%), which had been impregnated by the continuous compression molding machine considering the conditions of mass production. The representative flexural properties were statistically determined with the characteristic behavior of stress–strain curve. The coefficient-of-variation values were in the moderate range of around 5%, except for the strength and strain in minor direction that can be explained by the waving of fibers due to the lack of applied tension during and before impregnation.