Mechanical properties of aligned long glass fiber reinforced polypropylene. I: Tensile strength

Long-fiber reinforced thermoplastic composites were made from 9 mm long glass fiber reinforced PP pellets by alternative procedures of roll-mill and hot-press molding. The severe problem of fiber breaking during the process could be avoided by this method. The average fiber length of this composite was similar to 7 mm long. More than 80% of fibers in the composite were aligned within the 20 degrees range. In the major fiber-oriented direction, at 25 degrees C, the tensile strength of this composite was 205 MPa. At elevated temperatures in the range of 25 degrees C to 125 degrees C, the tensile strength was inversely proportional to the temperature. The two-parameter Weibull distribution function was used to simulate the strength distribution of the composite. Results showed that the strength distribution curve shifted from high to low as the temperature increased.