Robert A. Pett

Effects of aging on the fracture behavior of chlorinated polyethylene and chlorosulfonated polyethylene

Abstract The thermoxidative aging behavior of chlorosulfonated polyethylene (CSM) and chlorinated polyethylene (CPE) vulcanizates has been investigated. Aging rates were determined by measuring isothermal oxidative induction times in a differential scanning calorimeter. Aging rates were also determined by measuring the decrease in the critical tearing energy of compounds as a function of aging time and temperature. Rate constants determined from induction time and tearing energy experiments displayed typical Arrhenius behavior. Below 240°C, rate constants from both experiments fell on the same line, suggesting that both experiments probe the same reaction. Activation energies for degradation of CSM and CPE were 88 and 108 kJ/mol respectively. Above 240°C, the mechanism of degradation changes with a corresponding change in activation energy to 190 and 232 kJ/mol for CSM and CPE, respectively. In the unaged state, the critical tearing energy of the carbon black-filled CPE compound is 50% higher than that of...

A Fatigue Resistant Polychloroprene Compound for High Temperature Dynamic Applications

Abstract A polychloroprene material has been developed which can replace the natural rubber materials traditionally used in dynamic, fatigue-producing applications, when these applications require high temperature stability. An optimized compound based on a mercaptan modified polychloroprene with large particle high structure carbon black, silica filler and rapeseed oil has superior compression set, improved heat aged fatigue life and comparable dynamic properties to current NR compounds. This CR compound was designed to have good fatigue life while keeping compression set to a minimum. A positive correlation between tear resistance and fatigue life has been demonstrated for a series of CR compounds.

An Elastomeric Energy Storage Device for Automotive Engine Restart

Abstract An elastomeric spring starter using rubber in shear has been designed. Design criteria have been established and used to develop potential compounds for use in the device. Natural rubber proved to be the elastomer of choice primarily because of its excellent fatigue resistance. To reconcile bonding requirements and requirements for low hysteresis, the individual rings were fabricated from two elastomer compounds. Limitations on the thermal stability of the adhesive system were identified which put constraints on the operating conditions for the starter. A prototype starter has been assembled and installed in a vehicle. This prototype starter provides quiet, rapid starting of the test car. Questions of cost effectiveness, reliability, durability or manufacturing feasibility of this device have not been addressed. The starter was built for experimental purposes only and development of such a concept for mass production has not been explored.