EFFECT OF HYBRID CARBON BLACK/CARBON NANOTUBES FILLER ON VULCANIZATES RELAXATION BEHAVIOR

Abstract

The glass transition in hybrid carbon black/carbon nano-tube (CB/CNT) filled elastomer composites has been studied through dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The storage modulus E' and loss tangent (TanD) are recorded from -100 to 100 ° C and a frequency of 10 Hz. The thermal analysis was carried out at 2° C/min temperature increment. The vulcanizates were made as per conventional technology. The CNT were introduced into rubber compounds as CB/CNT masterbatches resulting from joint ultrasound processing. The CNT content in the rubber compounds varied from 0.1 to 0.5 phr. The DMA data proved that introduction of CB/CNT hybrid particles resulted in the spread of TanD temperature peaks for all the samples towards lower temperatures and the subsequent shift of the maximum TanD position by 4.0 to 15.6 degrees. The DSC data demonstrated the existence of additional low-temperature α-relaxation transitions in the modified vulcanizates (-123…-118 °C). The observed relaxation behavior could be explained by the increase in vacant volume in the vulcanizates along with the rise in segmental mobility of some macromolecules when compared against the reference sample. The highest hybrid filler content vulcanizate demonstrated certain TanD drop in the glass-to-rubber transition zone and the TanD rise in the high-elasticity state, which fact indicated formation of additional filler-filler interactions. Thus, the CNT treatment with carbon black resulted in a synergy effect upon the rubbers' dynamic characteristics; hence, it can be applied to the task of raising the material frost resistance point.