Evaluation of frequency dependent dynamic mechanical properties of natural rubber composites

Abstract

The dynamic mechanical properties of vulcanized elastomer play a newlinemajor role in the performance of many rubber products such as tyres. newlineDynamic mechanical analysis is a powerful technique for investigating the newlinemechanical behavior of materials based on its viscoelasticity. The complete newlineaccount of the viscoelastic properties can be obtained by performing newlinedynamic experiments over a range of time, temperature or frequency. The newlinedynamic mechanical analysis gives insight into the molecular environment newlineand helps to predict in-service performance of polymeric products. newlineIn a dynamic mechanical test, the applied frequency plays a vital role newlineto the materials mechanical response. The material becomes viscous or newlineliquid behavior predominates at low frequency range. The response is more newlineelastic or solid-like at relatively high frequencies. Thus the response of a newlineviscoelastic material to a forced deformation is time dependent. Since time newlineand frequency are inversely related, high frequencies are analogous to short newlinetimes and long times corresponding to low frequencies. This behaviour is also newlinesimilar to what happens with temperature changes. The change caused by newlineincrease of frequency is equivalent to that caused by decrease of temperature. newlineThe frequency sweep experiments can provide a finger print of a material. It newlineprovides an effective method to study the molecular weight and molecular newlineweight distribution. The modulus at frequencies below one reciprocal second newlineshows marked changes in the storage modulus as the molecular weight newlinedistribution is broadened for a polymer on deformation. In view of these newlinechanges, subsequent product improvements can be made through adjustments newlinein molecular weight distribution. Frequency scan studies at different newlinetemperatures can help to construct master curves to show the behaviour of newlinematerial over several decades of time and hence it is possible to predict the newlinelong term performance in specific operating conditions