Improvement in mechanical properties of recycled polypropylene composite by controlling the length distribution of glass fibers

Abstract

AbstractA change in the length distribution of glass fiber was induced by mixing long glass fiber 30%‐ reinforced polypropylene composites with recycled composites of short glass fiber 30%‐reinforced polypropylene, and the improvement in mechanical properties was investigated. Changes in mechanical properties were confirmed as a function of the number of recycles and mixing ratio of the composites, and the average fiber length and length distribution of the glass fibers were analyzed using a three‐dimensional measuring machine. The tensile strength, flexural strength, flexural modulus, and impact strength of the blend of a once‐recycled composite of short glass fiber‐reinforced polypropylene and once‐recycled composite of long glass fiber‐reinforced polypropylene in a ratio of 40:60 were 99%, 102%, 100%, and 100% those of a virgin composite of short glass fiber‐reinforced polypropylene, respectively. In addition, the average length of the glass fiber of this blend was 0.305 mm, which was similar to that of the virgin composite of short glass fiber‐reinforced polypropylene (0.313 mm); furthermore, the distribution ratio of long fibers of length 1 mm or more was 5%. The length distribution of the glass fibers was significantly altered by the combination of the recycled composites and the long glass fiber‐reinforced composite; accordingly, the deteriorated mechanical properties of the recycled composites could be significantly recovered.