INFLUENCE OF PROCESS INDUCED THERMAL DECOMPOSTION ON IMPACT STRENGNIGTII OF INJECTION MOLEDE HIGH DENSITY POLYETNYLENE (HDPE)

Abstract

The properties and behavior of plastics is still not well defined like metals and standard data sets for specific service applications are yet to be established. High Density Polyethylene is a plastic class which is expected to sustain extreme service conditions. The above mentioned aspect of exploring the plastics character stimulated the research. Molecular structure of this specified material was studied. Material processing through injection molding was examined .To analyze the impact behavior of this material, a series of experiments were conducted on variety of material samples molded at varying process melt temperatures and were subjected to impact testing with different conditioning environment. Apart from mechanical testing, thermal characteristic analysis and flow behaviour of various samples was also conducted. To further supplement the outcome of aforementioned lab test series, a real in service product manufactured from same material i.e. Butt Plate of Rifle G3 was also incorporated in this study and different samples were put to Radiographic examination and dynamic impact testing on a specially fabricated test bench. This additional dimension provided an opportunity to validate certain lab test deductions in a real service environment. Butt Plate material model was also simulated utilizing an injection molding analysis program “Mold Flow MPi3”. The predicted results generally agree to theoretical and experimental findings. The results analysis deduced that Material demonstrated comparatively best impact character in processing temperature range of 230 – 2400 C.Impact strength of material reduces when processed at 2500 C. Material suitably under service conditions at low temperatures should be carefully examined. Manufacturing process parameters of Butt Plate and its design need minor modifications to get desired working strength.