Wood flour: A new filler for the rubber processing industry. I. Cure characteristics and mechanical properties of wood flour-filled NBR and NBR/PVC compounds

In this study, conifer wood flour was evaluated as a filler to NBR or NBR/PVC compounds studying it influence on their cure characteristics and mechanical properties. It was shown that the filling by wood flour offers a possibility to obtain high modulus high elastic or less elastic or rigid wood like vulcanizates by varying of both the filling level and NBR/PVC mass ratio. It was established that in contrary to the mineral fillers usually causing significant delay of the vulcanization process, the wood flour shows a tendency to reduce the optimum cure time, tau(90). Modulus M-100 and Shore hardness of the wood flour-filled vulcanizates of NBR or NBR/PVC compounds in which NBR is predominant, increase in a compliance with the increase of M-max and DM when the filling level increases. The dependence is other when NBR and PVC are in equal amounts or PVC predominates. As a most probable explanation of the effect of the wood flour on the cure characteristics is accepted, the influence of the wood flour polar groups as well as of the presenting as wood flour humidity water molecules, the specific mechanical properties of the wood flour-filled NBR or NBR/PVC compounds could be connected (to some extend) with a specific interface interaction between the wood flour particles and the polymer matrix. (C) 2003 Wiley Periodicals, Inc.