Analysis

It is important to know the chemical characteristics of important non woody fibres like content of cellulose and lignin and ash.It is important to know the physical characteristics of nonwoody fibres like fibre length and fibre width. Graphical Presentation of chemical pulps physical characteristics. A very good survey where a certain pulp is positioned with other pulps can be seen in picture 1 , first developed by McGovern (9) and later perfected by Atchison.

A typical graph for kraft softwood (pine pulp) is B and for kraft hardwood (eukalyptus pulp) is K.

The data for mechanical pulps and DIP were added by Judt in picture 2. In the picture 2 and 3 an interdepence of tear factor and Burst factor for various pulps is shown. As burst is also a function of tensile and stretch a still wider knowledge of the pulps is possible.
In picture 3 one can see three areas of nonwoody pulps dependent on fibre length: Long fibres: 4 mm and longer. e.g. cotton, abaca (Manila hemp), kenaf, bast, ribbon.

Middle long fibres, between 1.5 and 4 mm: e.g. bamboo, reeds.Short fibres under 1.5 mm length, e.g. all straws, esparto, bagasse, kenaf, wooden core. The morphology of the different fibres is also important and can be studied in two excellent fibre books (10 and 11)

Important to know is that the elementar fibres of the plant species are characteristic for the plant and by chemistry or physics in the pulping process technologies they cannot be changed only damaged e.g. the fibre length of a parenchymcell of wheat straw is 1.4 mm and therefore a certain tear factor is only possible. Trials to influence the elementar cell length in sugar cane varieties in Cuba were abandened some years ago.

The quantity of Nonwood Market pulps is small, about 750 000 tons/year (4). It is known that by drying such pulps a lot of good characteristics are lost in the redispersed pulp, losses in tear, tensile and burst are higher than with wood pulps. Therefore nearly all Nonwood mills are integrated pulp and papermills. Or some high priced e.g. Abaca pulps are often traded wet (wet pressed )only.

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