Indentation behavior of new vegetable oil based thermoset copolymer

L. FASCE; C. MEIORIN; M. A. MOSIEWICKI

Rosario

Congreso; 11 Congreso Binacional SAM/CONAMET,; 2011

Tung oil based copolymers constitute a new type of polymeric systems with high amount of raw materials from renewable resources. The cationic polymerization of unmodified tung oil and styrene generates thermoset polymers with properties highly dependent on the tung oil/styrene ratio [1, 2]. These new polymers find potential applications as coating materials. Regardless the application, their functionality and reliability strongly depends on their mechanical performance. Depth sensing indentation is a suitable technique to evaluate mechanical properties of a broad spectrum of materials. However, to extract reliable parameters from the indentation response depends on the method of analysis, which in turn may depend on the material behaviour itself. The most widely spread method of analysis of load-depth curves is the Oliver-Pharr approach (O&P) [3]. This method considers that while the load is elasto-plastic, the unload is purely elastic and hence, it uses the unloading data together with geometrical relationships to extract reduced elastic modulus, Er, and hardness, H, values. In this work, the bulk indentation response of a copolymer based on vegetable oil is analyzed in order to extract reliable mechanical parameters from load-depth curves. This is the softer material studied of a series of tung oil based copolymers in which the transition temperature can be tailored by modifying the tung oil/styrene ratio [2]. It was selected due to its soft rubbery nature, for which interpretation of depth sensing indentation response is still not standardized.