Structural changes of modified polypropylene with thermoplastic elastomers for medical devices applications

Abstract

Poly(vinyl chloride) (PVC) is one of the most used materials with applications in the medical field. One approach to replace the phthalate plasticizers from PVC is to use other thermoplastic polymers having the same characteristics and performances as plasticized PVC. Modification of random polypropylene (PPR) by melt mixing technique with different thermoplastic elastomers: (poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) and poly(styrene-b-butadiene-b-styrene) (SBS) at various content ratios was investigation. The obtained blends were characterized by the determination of the elastomer content influence on density, crystallinity index, melting temperature, degree of crystallinity, crystallite size, and phase morphology. The results showed that the melting temperature of PPR/SBS blends was significantly lower than that of PPR/SEBS blends. Addition of SEBS or SBS to PPR had different effect on crystallite sizes and morphology of blends, and the same effect on decrease the degree of crystallinity of blends. The spectra of the blends by Fourier transform infrared spectroscopy indicated the presence of specific bands both for propylene, styrene, and ethylene-butadiene. Optical images revealed the appearance of regular and smaller SEBS domains than those of SBS in PPR matrix, making a high compatibility of SEBS with PPR matrix.