Dynamic Mechanical and Impact Property Correlation of Nanoclay and Graphite Platelet Reinforced Vinyl Ester Nanocomposites

Abstract

An experimental investigation was carried out to correlate the impact response of nanocomposites with the dynamic, inherent damping, and glass transition properties of Derakane 411-350 vinyl ester thermoset reinforced with 1.25 and 2.5 wt% Cloisite 30B nanoclay and exfoliated graphite nanoplatelets (xGnP). Dynamic mechanical analysis was performed to obtain the visco-elastic properties such as storage modulus (E'), loss modulus (E''), glass transition temperature (Tg) and loss factor (Tan δ). Low velocity impact tests were performed at an approximate strain rate of 15 s-1 on notched and un-notched Charpy samples using a drop-tower impact test system. Storage modulus was observed to increase with increasing nano reinforcements (max 40% for graphite platelet/vinyl ester nanocomposite). Loss factor also showed a significant increase of 80% with the addition of nanoclay, and 125% with graphite platelet. Glass transition temperature and loss modulus of nanoclay and graphite platelet reinforced nanocomposites also showed significant improvements over the pristine polymer. Low-velocity impact tests showed an increase of almost 100% energy absorption for un-notched samples with increasing nano reinforcement. However, a 70—90% reduction was observed in the case of notched samples. A direct correlation between impact response and dynamic mechanical properties for these vinyl ester nanocomposites was observed.