Syntactic foams are particulate polymer matrix composites made of microspheres spread throughout a matrix. Airplanes, spacecraft, and ships are all constructed using synthetic foams. These are lighter crystalline polymers employed for packaging, thermal insulation, sound absorption, building of undersea vehicles, and as the core of aircraft, sandwich structures. In this study, a Crump rubber-filled HDPE GMB and Syntactic foam polymer matrix composites is synthesized by mechanical mixing using Pelletizer and through injection moulding. Composites were fabricated accordingly keeping GMB composition constant of 20% and by varying percentage of Crump Rubber (5%, 10% and 15%), to study the impact of altering the volume percentage of Crump Rubber. Optimizing blending parameters based on experimental density estimates and filler fragmentation. Mechanical Characterization of the composite is evaluated according to ASTM standards. Study acknowledges the progressive improvement in mechanical characteristics (Impact, Tensile, Flexural and Hardness strengths) as Crump rubber is added to the composite.3