Effect of Fiber Length on the Short-Term Flexural Creep Behavior of Polypropylene

Abstract-Injection molded long fiber thermoplastic components are being used in recent days as a viable replacement for metals in many applications .Present work focus on the effect of fiber length on the short-term flexural creep performance of fiber reinforced thermoplastic polypropylene. Unreinforced polypropylene, 20 wt % short and 20 wt % long glass fiber reinforced polypropylene materials was injection-molded into flexural test specimens. Short-term flexural creep tests were performed for 2 h duration on molded specimen at various stress levels with the aid of in-house developed flexural creep fixture. Experimental creep performance of polypropylene composites for 2 h is utilized to predict the creep performance with the aid of four parameter HRZ model and compared with 24 h experimental creep data. Creep strain was found to be increased with respect to time for all the test materials and found to be sensitive with respect to the stress level. Test results also revealed that long fiber reinforced thermoplastic material possessed enhanced creep resistance over their counter parts and HRZ model is sufficient enough to predict creep performance of polypropylene composites over wide range of stress