The combined effect of impregnated rollers configuration and glass fibers surface modification on the properties of continuous glass fibers reinforced polypropylene prepreg composites

Abstract The continuous glass fibers (CGFs) reinforced thermoplastic composites play a crucial role in many applications such as automobile industry and aeronautic industry. However, there are two problems, one is how to regulate the degree of impregnation (M) and fracture rate of fiber bundle (P), and another is how to improve the interfacial properties. In this work, the different impregnated rollers configurations were designed to obtain appropriate M and P value, and the polyethylenimine (PEI) functionalized carboxylic carbon nanotubes (PEI-CNT) were grafted to the CGFs (PEI-CNT-CGFs) surface through dipping method, which is beneficial to the interfacial properties between CGFs and polypropylene (PP). Both theoretical and experimental results indicated that optimal configuration (F) could achieve ultrahigh degree of impregnation of 99.37% at relatively low fracture rate (3.58%) of fiber bundle, so that the tensile strength was improved dramatically (from 329.3 MPa to 461.8 MPa). Furthermore, the PP/PEI-CNT-CGFs composite manufactured in F configuration showed higher tensile strength (486.3 MPa) due to the better interfacial adhesion, it was an obvious consequence from the SEM images of fractured surface in PP/PEI-CNT-CGFs. This study provides a strategy to obtain ultrahigh performance of CGFs reinforced PP composite by improving degree of impregnation as much as possible with limited fiber breakage, and enhancing interfacial adhesion. It is hugely significant to guide the production of CGFs reinforced thermoplastic prepreg composites.