Studies on Thermal and Mechanical Properties of Polybenzoxazine Modified with Succinic Acid

Abstract

Polybenzoxazine (PBA-a), a novel type of phenolic resin, possesses many outstanding properties, i.e. good mechanical strength, electrical insulation, dimensional stability, resistance against many types of solvents, flame retardation, and low smoke emission from burning. However, shortcoming of this material is from its brittleness. In this study, the rigidity of polybenzoxazine was improved by adding succinic acid (SA) as plasticizer. The content of SA was varied from 0 to 50 phr. The thermal properties were determined by Differential Scanning Calorimeter (DSC) and Thermogravimetric Analyzer (TGA), while the mechanical properties were analysed by Universal Testing Machine (UTM) and Microhardness tester. In addition, the results that the glass transition temperature (Tg) of PBA-a was decreased with increasing the amount of SA, i.e. decreasing from 168°C (0 phr) to 121°C (50 phr). Furthermore, the degradation temperature at 5 % weight loss (Td5%) was decreased from 328°C (0 phr) to 240°C (50 phr). It could be noticed that the char yield of the polymer at 800°C had no significant change (in the range of 30-33%) when SA was added. The polybenzoxazine exhibited softening decreased of hardness from 39.8 MPa (at 0 phr) to 9.62 MPA (at 50 phr).