Cellulosic materials composition

The principal application of melamine-formaldehyde moulding compositions is for the manufacture of tableware, largely because of their wide colour range, surface hardness and stain resistance. The stain resistance does, however, leave something to be desired and one aim of current research is to discover alternative materials superior in this respect. Cellulose-filled compositions also find a small outlet for trays, clock cases and radio cabinets and other purposes. The mineral-filled powders are used in electrical applications and knobs and handles for kitchen utensils. 

The cellulosic-reinforced composite materials (i.e., synthetic wood) are suitable for a wide range of applications including [62] (A. U. Ferrari, Mobil Chemical Comp., personal communication, 1994) ... 

Potential advantages of both thermoplastics and cellu-losic materials combined with the economic and environmental viewpoint have lead to a promising utilization of both these materials in various forms of composites. Although various branches of cellulosic-thermoplastic composites industries are booming in recent years, their growth rate is very slow. In order to achieve the full potential of such valuable materials as various engineering materials and commodity products more incentives from academic, industrial, and governmental authorities are needed. 

The choice of material for use as inhibitor depends mainly upon the type of propellant, that is, DB, CMDB, Composite and Fuel-rich and also on the ingredients in their formulations. For double-base propellants, cellulosic materials such a cellulose acetate, ethyl cellulose and different filled or unfilled flexible polyesters are used while fuel or binder material filled with inert substances such as asbestos, mica, silica, etc. in fine powder form is used for composite propellants. Since nitroglycerine is present in CMDB propellants also as in DB propellants, the materials used for DB propellants may also be used with minor modifications for the inhibition of CMDB propellants. 

Sodium borate solutions near the Na20 B203 ratio of maximum solubility can be spray-dried to form an amorphous product with the approximate composition Na20 4B203 4H20 commonly referred to as sodium octaborate (64). This material dissolves rapidly in water without any decrease in temperature to form supersaturated solutions. Such solutions have found application in treating cellulosic materials to impart fire-retardant and decay-resistant properties (see Cellulose). 

A more recent trend in polymer materials research is the hybridization of cellulosic polysaccharides with inorganic compounds natural and synthetic layered clays, silica, zeolites, metal oxides, and apatites are employable as nanoscale components. In addition, if mesoscopic assemblies such as liquid-crystalline ordering are used in the construction of new compositional systems, the variety of functionalized cellulosic materials will be further expanded. 

The nature and composition of the volatile products, and the quantity of the char, determine the flammability of the cellulosic material and the rate of combustion or propagation of the fire, which is highly sensitive to the effect of the physical and environmental conditions prevailing, as well as to the chemical factors, such as the minor components and inorganic compounds present. 

The former variables affect the deposition of heat in the solid fuel and its transient temperature-profile, as well as the diffusion of the volatile pyrolysis products and their distribution and mixing with the surrounding atmosphere. The latter factors influence the nature and sequence of the primary and secondary reactions involved, the composition of the flammable volatiles, and, ultimately, the kinetics of the combustion. Consequently, basic study of the combustion of cellulosic materials or fire research has been channeled in these two directions. 

From these considerations a completely satisfactory chemical definition of cellulose cannot be given at present, but for the purposes of this discussion the term will be used in a plural sense somewhat more comprehensive than that employed by Payen. The term cellulosic material or purified cellulosic material will be used interchangeably with the term cellulose, but is meant to convey the same idea concerning composition. 

Particles, which are generally produced from wood although other cellulosic materials have been used, with straw being used in Europe early in the development of composites. 

The raw materials required to produce cellulase are cheap and abundant. Natural cellulosic materials such as plant stems and corn cobs can be used as the carbon source. The composition of the medium is simple and of low cost. Because of the high capability of cellulosic materials to buffer the pH value, it is not necessary to add additional expensive buffer solution. 

It is a commonly held view that cellulase is an inducible enzyme, and that cellulose is the best inducer. In solid-state fermentation for cellulase production, cellulosic materials act as either the carbon source or the inducer. Some of the raw materials for solid-state fermentation and their composition are listed in Table 1. From Table 1 it is very clear that the raw materials for cellulase production using solid-state fermentation are abundant and cheap. Proper pretreatment of raw materials is generally required. The nitrogen source for solid-state fermentation includes inorganic compounds, such as urea and (NH4)2SO4, or natural products, such as bran. 

Table 1. Approximate composition of selected cellulosic materials...

U.S. Pat. No. 5,474,722 [38] describes a composite material 20-80% of which is a cellulosic material (ground wood, sawdust, wood flour, rice hulls, etc.) and polyethylene. 

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