Development of Granite-Filled Recycled LDPE Composites for Lightweight Military Helmet Applications

The development of a lightweight military helmet using granite particulate (GTP) reinforced recycled low-density  polyethylene (RLDPE) was studied in an attempt to produce a light helmet with high strength and cost-effective material  for military applications. This study utilised the abundant presence of granite in the ecosystem. The granite stone was  washed using distilled water and detergent and sun dried, then ball milled for 72 hours. The process was followed by  compounding the granite powder with recycled low-density polyethylene (pure water sachet) and compatibiliser  (propylene glycol) in a two-roll mill compounder at a temperature of 150℃ for 5 minutes. Six samples were produced  by varying the composition of granite from 0 to 50 wt. % (at regular interval of 10%), one of the six samples is a control  sample and it was used to compare the other samples. The samples were characterised using SEM and then tested for  hardness, tensile, flexural and impact strengths, and density. The SEM images showed dispersion of the GTP.  Additionally, mechanical properties improved with the addition of the filler while density depreciated mildly, especially  at 10% loading.