Compatibilization of Polycarbonate/Silicon Rubber Blend with Styrene/Silicon Oil/Acrylonitrile Ternary Copolymer for Ultra-High Low-Temperature Toughness

Abstract

The higher notch sensitivity of polycarbonate (PC) at low temperatures limits its application in some fields. In this work, a ternary copolymer P(St-SiO-An) composed of styrene (St), silicon oil (SiO), and acrylonitrile (An) was synthesized via a conventional radical copolymerization. Then, the compatibilities between PC/silicon rubber (Sr), PC/P(St-SiO-An), and P(St-SiO-An)/Sr were predicted through molecular dynamics simulation. By using P(St-SiO-An) as the effective compatibilizer, a series of PC/ Sr blends were prepared via the melt blending method. The mechanical, morphological, thermal, and rheological changes of the blends were investigated in detail. The molecular dynamics simulation showed that the compatibilities of PC/P(St-SiO-An) and P(St-SiO-An)/Sr pairs were significantly higher than those of the PC/Sr pair. P(St-SiO-An) ternary copolymer with a distinct chemical composition was synthesized successfully according to the results of Fourier transform infrared, 1H nuclear magnetic resonance, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis methods. Under the optimal composition of PC/Sr = 95/5 with 4 phr of P(St-SiO-An), a transition from brittle to superductile fracture was observed on the notched impact cross-section of the blend at −40 °C, and the notch impact strength reached 116.2 kJ/m 2 , which was more than 7 times that of 16.5 kJ/m 2 for pure PC with a 94.1% yield strength retention ratio at room temperature. Cavitation-matrix-forced high elastic deformation was the main toughening mechanism at low temperatures. Furthermore, the introduction of Sr and compatibilizer hardly affected the thermal performance of the PC, and the thermal stability and processability were enhanced. Compared with the SABIC EXL series commercial PC, the blend in this work shows great advantages in preparation methods and comprehensive properties, which are expected to further broaden the application of PC in the field of low-temperature resistance.