SOME ASPECTS OF WHEAT STRAW FINES ON PAPER PROPERTIES

Wheat straw, a domestic non-wood fiber, can potentially replace the virgin short fiber in the manufacture of fine paper in the future provided that it is bleached with an environmental friendly method. A possible draw-back of using wheat straw is the presence of a large fines fraction with functions that are not well known. It has been reported by Guo(2) that the wheat straw fines fraction contributes neither to strength or optical properties. This paper tries to further understand the fines fraction by comparing the influence of primary and secondary wheat straw fines on both the mechanical and optical properties of handsheets. Both image analysis based fiber dimension quantification instrument and light microscopy were used to gain further insight into wheat straw. The results showed that the fines fraction of wheat straw, consisting of a large amount of different cell types (primary fines), contributed less to most strength properties compared to fines generated by refining (secondary). Optical properties of handsheets differ little between the two types of fines. The difference in the handsheet properties observed by these two types of fines may be due to the lower surface charge of the primary fines.