Chemical treatment benzoylation

Peroxide treatment Natural fibres are immersed in a solution of dicumyl (or benzoyl) peroxide in acetone for about half an hour, then decanted and dried [123]. Recent studies have highlighted significant improvements in the mechanical properties. In a study of polyethylene hybrid composites, sisal and glass fibres were proposed to reinforce the matrix in terms of tensile strength and modulus. Among different chemical treatments, benzoyl peroxide treated fibres revealed to be more successful. This was attributed to the peroxide-initiated grafting of polyethylene on to the fibres [124]. 

Annie Paul et al. [36] studied short randomly oriented PP/banana fibre composites. The thermophysical properties of the above composites were studied on the basis of different banana fibre loading and different chemical treatments given to the banana fibres. The incorporation of banana fibres into PP matrix induced a decrease of the effective thermal conductivity of the composite. The use of the theoretical series conduction model allowed to estimate the transverse thermal conductivity of untreated banana fibre composites. As was expected, the series model appears sufficient for the effective thermal conductivity estimation of this kind of composites. All the chemical treatments enhanced both thermal conductivity and diffusivity of the composite considerably in varying degrees. This indicates that the chemical treatment allows a better contact between the fibre and the matrix and reduces considerably the thermal contact resistance. Nevertheless, a significant increase of the thermal conductivity was observed only for benzoylated and 10% NaOH-treated fibre composites. Besides, the variations of density and specific heat upon fibre chemical treatment are small compared to their associated uncertainties. 

Sometimes, degree of adhesion between fiber and matrix achieved through various primary processing of biocomposites is weak which results in poor performance of developed composites. Natural fibers comprise of waxy and fatty materials on their surface which causes improper bonding between fiber and matrix. There are various chemical treatment techniques (such as alkali-treatment, silane treatment, Benzoylation, Acetylation, etc.) which can be applied to natural fibers before primary processing to condition the surface and consequently improve the fiber matrix adhesion to develop high performance biocomposites. 

The chemical treatments such as benzoylation, polystyrene maleic anhydride (PSMA) coating and acetylation of short sisal fibers have been found effective in improving fiber matrix adhesion of polystyrene/sisal composites. It has been reported that the... 

However, after chemical treatment of C. indica fibers, dielectric constant values of finally fabricated biocomposites have been found to be lowered, which could be due to the decrease in orientation polarization of polymer composites containing surface-modified fiber. We have reported earlier that benzoylation reduces the moisture absorption behavior of fibers because of blockage of —OH groups on cel-lulosic fiber backbone. Thus resultant decrease in hydrophUicity of the polymer composites leads to lowering of orientation polarization and ultimately dielectric constant value [22]. It has also been observed that mercerization is one of the most effective methods in the reduction of dielectric constant values of the obtained biocomposites. 

Some examples for the isolation of the desired poly(trifluoromethyl) compounds from product mixtures by chemical purification have been reported.128 129 In the reaction of benzene-1,2,3-tricarboxylic acid with sulfur tetrafluoride/hydrogen fluoride a mixture of l,2,3-tris(tri-fluoromethyl)benzene (9), l,l,3,3-tetrafluoro-4-(trifluoromethyl)-l,3-dihydroisobenzofuran (10), and 2.6-bis(trifluoromcthyl)benzoyl fluoride (11) is obtained in a 1 3.5 13 ratio.129 Treatment of the mixture with aqueous potassium hydroxide, followed by acidification, yields pure 2,6-bis(trifluoromethyl)benzoic acid (12). 

Taxol is a natural product isolated in very low yield from Taxus brevifolia and is used in the treatment of cancer (110). The extreme chemical complexity of Taxol makes production by total synthesis uneconomical. However, a semisynthetic approach using the naturally derived 10-deacetylbaccatin III (66) condensation with iST-benzoyl-(2J2, 3S)-3-phe-nylisoserine (67) does provide an alternative and economic approach (111). N-benzoyl-(2J2, 3S)-3-phenylisoserine (67) is also commonly known as the Taxol side-chain and has been prepared in optically active form using chiral auxiliaries or resolving agents (112). It has been shown that the Taxol side-chain is a conglomerate and can therefore be cheaply and... 

Native cellulose are commonly modified by physical, chemical, enzymic, or genetic means in order to obtain specific functional properties, and to improve some of the inherent properties that limit their utility in certain application. Physical/surface modification of cellulose are performed in order to clean the fiber surface, chemically modify the surface, stop the moisture absorption process, and increase the surface roughness. " Among the various pretreatment techniques, silylation, mercerization, peroxide, benzoylation, graft copolymerization, and bacterial cellulose treatment are the best methods for surface modification of natural fibers. 

Eor pretreatment of sisal fiber chemicals such as alkali (NaOH), permanganate (KMn04), acetylation, peroxide (BPO and DCP), isocyanate treatment, stearic acid, silane, benzoylation [79], maleic anhydride modification, PPG-TDI [34, 60, 61], and cold-plasma treatment are used [76, 118]. 

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