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Abstract

Part I of this series demonstrated the effects of recycled polymer inclusion on the tensile properties of oriented polypropylene tapes. Part II describes the effects of re cycled waste on structure and morphology. Under constant conditions of tape extrusion and drawing, the IR crystallinity of orientated tape shows a U-shaped relationship with waste concentration. There is a sudden drop of crystallinity at low waste concentration, which passes through a minimum with increasing waste content, and then gradually rises to the lower crystallinity value of the tape containing 100% waste. Sonic modulus and birefringence values decrease with increasing waste concentration. These changes in tape crystallinity and orientation, along with decreasing molecular weight, explain the loss of tape tenacity owing to the introduction of waste polymer during extrusion. Improved molecular orientation is evident in the presence of additional antioxidant stabilizer, because polymer chain degradation during processing is reduced.

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