Secondary fibres

The primary sources for the mineral oil contamination in secondary fibre-based packaging materials are the coldset inks from newspapers because offset printing is the dominating printing process for this type of graphic paper product in Europe. Offset coldset inks consist of up to 30% of mineral oil as solvent. In general, offset inks are available which are based on mineral oil-reduced or mineral oil-free... 

Pulp and Paper Manufacture, Vol. 3 Secondary Fibres and Non-wood Pulping , TAPPI and CPPA. 

Opinions vary as to the optimnm point to add a dry strength resin, and indeed this can differ from one paper machine to another. It will also to some extent depend upon the specific objectives for nse. The most commonly nsed point of addition is to the thick stock, after the last refining has been carried ont. Strazdins [13] reported a laboratory study on a European secondary fibre fnmish, where the benefits of resin addition to the long fibre fraction were demonstrated. Good mixing is essential to obtain the best performance from the product, so addition to a weU-stirred chest or the down leg of the thick stock level box is ideal. If the dilnte resin is added to a pipeline, optimum mixing will be achieved if a mnltipoint injection system is nsed. 

Ghosh, A.K. (2004) Refining Optimization of Secondary Fibre - use of Bijective Diagram Technique, Peer-reviewed Paper presented in the APPITA/Pan Padfie Conference held at Canberra, Australian on April 19-21, 2004. 

Acanthothiris spinosa (Schlotheim), a rhynchonellide. Bath, England Middle Jurassic (Inferior Oolite) SM j 57767. A spine stump close to the valve margin partially covered by primary shell showing the growth of secondary fibres towards the suture line. SEMx90. 

The secondary fibre is formed later in the development of the plant and decreases the technological value of the fibre while it is strongly lignified, stiff and difficult to divide. The quality and amount of fibre in the stem is an outcome of the effects of numerous natural and agricultural factors, mostly on the cultivar (genetic potential), type of soil and fertilizer supply, sowing density, time of harvesting, etc. 

As mentioned before, the primary fibre (the most interesting material from a processing point of view) is distributed along the whole stem, with the highest concentration in the middle part of the stem. It is formed in the apex from the meristem before the end of flowering. The secondary fibre is contained mainly in the lower part of the stem and is formed later in the development. The parameters of the fibre and a comparison with flax fibre are presented in Tables 2.V-2.9 [9]. 

Secondary fibres medium in length and higher in hgnin. 

It is interesting that cellulose-pulp tested as single fibres do not fracture simply [28], but rather fail by separation between the layers of the secondary fibre wall. In contrast, in the cement composite the fibre fracture seems to be clean, without layered separation within the fibre. It has been suggested that the cement matrix may have entered the fibre and led to additional internal bonding in the cell wall. This may be the first step in the petrification process described by Bentur and Akers [42]. 

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