Effects of Malonic Acid Treatment on Crystal Structure, Melting Behavior, Morphology, and Mechanical Properties of Isotactic Poly(propylene)/Wollastonite Composites

摘要

Wollastonite is treated with a new surface modifier (maionic acid). The influence of malonic acid treatment on the crystallization and mechanical properties of polypropylene (PP)/wollastonite composites has been studied. The results of differential scanning calorime-try, wide angle X-ray diffractometry, and polarized light microscopy prove that malonic acid-treated wollastonite increases the relative content of β-crystal form of PP. The scanning electron microscopy shows that malonic acid-treated wollastonite has better compatibility with PP matrix than the untreated wollastonite. Higher β-phase contents, smaller spherulite sizes, and better compatibility with PP matrix of the composites containing malonic acid-treated wollastonite result in improved impact strength and tensile strength, but lower flexural modulus. The results of Fourier transform infrared spectroscopy show that malonic acid reacts with the Ca~(2+) of wollastonite to form the calcium malonate, which acts as an effective /{-nucleating agent.