In this work, the tensile specimen of various polymers, namely (Polycarbonate (PC), Polyketone (PK), Polypropylene (PP), Polyurethane (PU), and Ethylene Vinyl Acetate (EVA)) were fabricated using two different manufacturing processes, viz. Injection Molding and Sigma Mixing. Creep and stress relaxation properties of these polymers have been evaluated using Creep Testing Machine. It has been observed that the creep modulus was enhanced by 20.6% in the sigma mixed material in comparison to injection molded specimen and the strain rate increased by 150.14% in the sigma mixed specimen; on the other hand, residual stress which was deduced from the stress relaxation tests decreased by 11.5% on an average in the sigma mixed material in comparison to injection molded materials. Since the sigma mixing process improves the intermixing of the granules because of the motion of the mixer rollers, it causes the increase in the bond strength in the sigma mixing process. Enhanced creep modulus and reduced strain rate enables these polymers to be used for applications which require service under a constant load for a prolonged period of time.