Sisal, cellulose

NATURAL SOURCES Wood (coniferous, deciduous), bamboo, cotton, hemp, straw, jute, flax, reed, sisal. Cellulose is isolated from the plant cell walls and is never in a pure form in nature. Always associated with lignin and hemicellulose. ... 

G.T. Ciacco, TF. Liebert, E. Frollini, TJ. Heinze, Application of the solvent dimethyl sulfoxide/tetrabutyl-ammonium flumde trihydrate as reaction medium for the homogeneous acylation of sisal cellulose, Cellulose 10 (2) (2003) 125-132. 

Garcia de Rodriguez, N.L., Thielemans, W., Dufresne, A. Sisal cellulose whiskers reinforced polyvinyl acetate nanocomposites. Cellulose 13, 261-270 (2006)... 

Influence of the amount tetra- -butylammonium fluoride (TBAF) trihydrate ou the efficieucy of the acetylation of sisal cellulose with acetic anhydride in dimethyl sulfoxide (DMSO)/TBAF (adapted from [28])... 

Fukuzumi H, Saito T, Iwata T et al (2008) Transparent and high gas barrier films of cellulose nanofibers prepared by TEMPO-mediated oxidation. Biomacromolecules 10 162-165 Garcia de Rodriguez NL, Thielemans W, Dulfesne A (2006) Sisal cellulose whiskers reinforced polyvinyl acetate nanocomposites. Cellulose 13 261-270 Gousse C, Chanzy H, Excoffier G et al (2002) Stable suspensions of partially silylated cellulose whiskers dispersed in organic solvents. Polymer 43 2645-2651 Gray DG (2008) Transcrystallization of polypropylene at cellulose nanocrystal surfaces. Cellulose 15 297-301... 

Acid anhydrides have been employed with, and without the use of a base catalyst. For example, acetates, propionates, butyrates, and their mixed esters, DS of 1 to ca. 3, have been obtained by reaction of activated cellulose with the corresponding anhydride, or two anhydrides, starting with the one with the smaller volume. In all cases, the distribution of both ester groups was almost statistic. Activation has been carried out by partial solvent distillation, and later by heat activation, under reduced pressure, of the native cellulose (bagasse, sisal), or the mercerized one (cotton linters). No catalyst has been employed the anhydride/AGU ratio was stoichiometric for microcrystalhne cellulose. Alternatively, 50% excess of anhydride (relative to targeted DS) has been employed for fibrous celluloses. In all cases, polymer degradation was minimum, and functionalization occurs preferentially at Ce ( C NMR spectroscopic analysis [52,56,57]). 

Xylan occurs in practically all land plants and is said to be present in some marine algae.6 In both wide botanical distribution and abundance in nature it closely follows cellulose and starch. It is most abundant in annual crops, particularly in agricultural residues such as corn cobs, corn stalks, grain hulls and stems. Here it occurs in amounts ranging from 15 to 30%. Hard woods contain 20 to 25% xylan while soft woods contain 7 to 12 %. Spring wood has more pentosan than summer wood. 7 Low strength vegetable fibers of commerce such as jute, sisal, Manila... 

Secondary-cellulose deposition occurs after cessation of expansion of the primary wall. Layers of the secondary wall, in contrast to the primary wall, display a very orderly, parallel arrangement of the microfibrils. In such plants as flax and hemp,1,2 bamboo,13 sisal,14-16 cotton hairs,2 and pine tracheids,13 three main layers can be detected in the secondary wall, each made up of cellulose microfibrils arranged in a helical fashion around the cell, In each of these secondary walls, the middle layer of cellulose is considerably thicker than the cellulose layers on each side of it, with a helical direction opposed to those of the latter. It is probable that each of these three layers is, in fact, complex, and made from a number of lamellae, each with its own helix of cellulose microfibrils.1 2... 

The large-production reinforcing agent used today is primarily glass. Other fibers include cotton, cellulosic fiber, sisal, polyamide, jute, carbon, graphite, boron, whiskers, steel, and other synthetic fibers.10 12> 289 291, 466 They all offer wide variations in composition, properties, fiber orientation/construction, weight, and cost (Tables 15.4 and 15.5... 

Fillers used in large quantities to reinforce plastics are alumina (aluminum oxide), calcium carbonate, calcium silicate, cellulose flock, cotton (different forms), short glass fiber, glass beads, glass spheres, graphite, iron oxide powder, mica, quartz, sisal, silicon carbide, dtanium oxide, and tungsten carbide. Choice of filler varies and depends to a great extent upon the requirements of the end item and method of fabrication. 

Debye-Scherer X-ray difiiaction pattern of a sisal fiber. The arcs in this pattern indicate the crystalline nature of the main constituent, cellulose. 

Cotton and Linen Cloth, etc.— The two most important sources of cellulose for the manufacture of thread and cloth and similar articles are the holl of the cotton plant and the stalk of the flax plant. The former is the source of all goods known as cotton while the materials made from the latter are termed linen. Another important fibre plant is hemp, the leaves or stalk of which yields fibres which are principally used in making twine, rope and canvas. Several varieties of hemp are used such as manila hemp, sisal, etc. The stalk of ihtjute plant is the source of materials out of which sacking or burlap and carpets are made.. In the manufacture of these products the fibre of the plant is mechanically separated and then spun into thread or twisted into yarn or rope. The thread or yarn are then woven into fabrics. The products possess properties characteristic of the particular fibre used. As in the manufacture of all of these important materials the cellulose undergoes no chemical change but is simply mechanically treated no further details of the processes will be given. 

Various reports are present in the literature on the usage of cellulose fibers in the preparation of composites. Cellulose fibers like banana, sisal, oil palm, jute, pine apple leaf fiber were found to have a very good reinforcing effect on polymer matrices [38 2]. The mechanical properties and water absorption were found to be dependent on the amount of micro-fibrils. 

Cellulose (12.23)70 is found in wood, along with about 24% hemicellulose and 22% lignin, and in cotton, sisal, jute, linen, hemp, and other similar products. It is a polymer of glucose. 

U.S. Pat. No. 6,255,368 [114] describes plastic cellulosic composite pellets comprising 20-60% by weight of polyethylene, polypropylene or polystyrene, 40-80% of cellulosic fiber (jute, kenaf, sisal, bamboo, rice hulls, corn husks, wood fiber, and wood flour) with an aspect ratio of between 2 and 20 and a trace of mineral coating (talc) dispersed on the surface of the pellet. 

Long fiber cellulosics, such as flax, hemp, jute, ramie, coir, sisal, and cotton, all have density in WPC materials also in the 1.3-1.5 g/cm range. 

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