Effect Of Nr Molecular Weight And The Dispersion Of Carbon Black On Dynamic Properties Of Nr/Carbon Black Composites

The study of natural rubber nano-composites material is still in its infancy, Domestic research mainly focus on the study of the influence of different components and processes on the properties, while little research on the molecular weight of rubber as well as the relation between nano-filler interaction and filler dispersion. In this paper, the effects of nature rubber molecular weight and the dispersion of carbon black on dynamic properties of NR/carbon black composites were studied based on the natural rubber latex, and at the same time, the samples were prepared by the latex co-agglomeration. In addition, rubber crosslinking density spectrometer, scanning electron microscopy, RPA2000rubber processing analyzer and other advanced instruments were used to characterize the performance. The results were showed as follows:(1) The elastic modulus of raw nature rubber declined in nonlinear with the increasing stain amplitude which illustrated that the rubber molecular chain entanglement had contribution to the modulus of raw nature rubber. The rubber molecular weight was larger, the greater the elastic modulus at low stain amplitude and the bigger difference value between the high modulus and the low modulus as well as the greater the contribution of the rubber network to the modulus, and the interaction bwtween rubber chain became strongger. At the same time, the interaction between the molecular chains could be reflected by elastic modulus of raw nature rubber at high stain amplitude, and the modulus differerce value between high and low stain amplitude can be used to characterize the entanglement strength bwtween rubber molecular chains.(2) Both of the compounds and vulcanizates added with surfer or surfer, ZnO and accelerator, their elastic modulus declined in nonlinear with the increasing stain amplitude which illustrated that the rubber molecular chain entanglement had contribution to the modulus of compounds and vulcanizates. The rubber molecular weight was larger, the greater the elastic modulus at low stain amplitude and the bigger difference value between the high modulus and the low modulus while the loss factor and its increase scope were smaller. The influence of the molecular weight on the elastic modulus of NR became greater while that on loss modulus and loss factor became smaller after vulcanization.(3) As to both the compounds and the vulcanizates filled with carbon black, their elastic modulus declined in nonlinear with the increasing stain amplitude which called Payne effect. And the more the content of carbon black, the rubber molecular weight was large as well as the Payne effect was obvious. In addition, the Payne effect was influenced by both the rubber network and the filler network, at the same time, the rubber molecular weight was larger, the greater the contribution of the rubber network to the modulus.(4) As to both the raw nature rubber and the compounds filled or unfilled carbon black, their elastic modulus raised and the loss factor declined with increasing frequency and decreasing temperature while the elastic modulus and the loss factor were both raised as to the vulcanizates. The greater the rubber molecular weight, the sensitivity of the elastic modulus and the loss factor to frequency was small while that to temperature was greater.(5) Under the condition that the rubber molecular weight remained unchanged, the better dispersion of carbon black, the Mooney viscosity and dynamic modulus were smaller and the loss factor was larger At the same time, the better dispersion of carbon black, the Payne effect was decrease, and more strain amplitude were needed to break the filler network...