Abstract: pH value of renewable polymeric materials is usually determined according to the method described by Browing in which the material of a fixed solid/water ratio was used.This method represents only one ratio to reflect it's pH value,which has the obvious defects of ignoring the variations of water content caused by environmental variation.In this study,Browning's method was modified by measuring a series of pH values of Pinus sylvestris L.wood of different solid/water ratios to plot curve,which exhibits good linear correlation.By extrapolating the linear line,an unique pH value was obtained which was defined as its intrinsic pH value.Finally,a comparison of intrinsic pH values of some typical renewable polymeric materials with their pH values normally obtained by traditional Browning's method has been made.

Key words: renewable polymeric materials, intrinsic pH value, Pinus sylvestris L.