Mechanical and Aging Properties of Polypropylene and Styrene-Isoprene-Styrene Composites at Low Temperature and Under Outdoor Conditions

Polypropylene (PP) and styrene-isoprene-styrene (SIS) blends with different mass fractions were prepared by twin-screw melt extrusion. PP/SIS was analyzed with differential scanning calorimetry, a universal material testing machine, capillary rheometry, X-ray diffractometry, and X-ray photoelectron spectrometry. The SIS content effect on the microstructure and properties was discussed, and the morphology and mechanical properties of outdoor-aged PP/SIS samples were studied. The SIS addition is shown to improve the PP toughness. Low-temperature tests and dynamic thermal analysis demonstrate that the low-temperature PP brittleness can be effectively enhanced by a good low-temperature SIS toughness. Indoor and outdoor aging tests revealed that the PP/SIS samples were greatly affected by the outdoor climate, but in comparison with pure PP samples, the properties of blend samples still have certain advantages offered by simple blending modification.