Wood flour: New filler for the rubber processing industry. IV. Cure characteristics and mechanical properties of natural rubber compounds filled by non-modified or corona treated wood flour

It is presented here how some cure characteristics and mechanical properties of rubber compounds based on nonpolar rubber, natural rubber (NR), are affected by filling with conifer wood flour, both nonmodified or corona treated in air or in ammonia. The corona treatment was performed at room temperature and varied both: treatment duration and voltage to find out the maximal reinforcing effect of the modified wood flour. The discharge voltage was varied at 10, 12, and 15 kV to include both (1) the range of relative low voltages (lower than 10 divided by 12 kV in which the major active species arise from ionized and activated air oxygen and (2) the range of relative high voltages (12 kV and higher) in which the active species arise from simultaneously ionized and activated air oxygen and nitrogen. The chemical composition of the nonmodified and corona-treated wood surface was controlled by X-ray photoelectron spectroscopy (XPS) analysis. The activity of the modified wood flour was evaluated by comparative measurement of some basic mechanical parameters of rubber compounds, filled at equal level by nonmodified or plasma-treated wood flour. (c) 2006 Wiley Periodicals, Inc.