Pretreatment of cellulose

In one study [90], enzyme pretreatment increased colour yield without affecting fastness properties. However, pretreatment of cellulosic fibres with cellulase lowered the subsequent fixation of homobifunctional triazine reactive dyes but did not impair the fixation of other types of reactive dyes [91]. Another study suggested that the enhanced brightness of reactive dyeings was greater with triazine dyes than with vinylsulphone types when cotton was pretreated or aftertreated with cellulase [92]. 

POLYRON KB is a special product for the pretreatment of cellulosic fiber and its mixtures. The sequestering action upon alkaline-earth metals and heavy metal ions is very effective in the high alkaline region. 

Table 1 summarizes some representative solvents or solvent systems for cellulose. The xanthate system has been used for a longtime to make viscose rayon and sponge. However, rayon production, where H2S is released to varying amounts during the recovery system of spent solvent, is shrinking because of environmental issues. On the other hand, cellulose is soluble in aqueous NaOH alone under limited conditions. Microcrystalline cellulose with DP 200—300 is soluble in 6—9% NaOH by freezing and defrosting procedures. Pretreatments of cellulose such as steam explosion are necessary for complete dissolution in the aqueous NaOH for normal bleached wood pulp and cotton linters with DP of more than 500. ... 

LiCI/DMAc, LiCI/DMI Stable needs pretreatment of cellulose... 

The key opportunities for pollution prevention in pretreatment of cellulosic substrates are as follows [100,88,162] ... 

Pretreatment of cellulose pulp with caustic soda... 

Supercritical CO2 explosion was found to be effective for pretreatment of cellulosic materials before enzymatic hydrolysis 50, 51). Zheng et al. 52) compared CO2 explosion with steam and ammonia explosion for pretreatment of sugarcane bagasse and found that CO2 explosion was more cost-effective than ammonia explosion and did not cause the formation of inhibitory compounds that could occur in steam explosion. 

The new fiber-modification technique is based on cationic acrylic copolymer. Pretreatment of cellulosic fiber with polymer is believed to offer an opportunity for increasing both the substantivity and reactivity of fibers towards reactive dyes under neutral conditions. The nature of a reactive polymer resin is such that it may react with nucleophilic sites in cellulosic fibers or in the polymer itself, thus fixing the polymer to the substrate. During subsequent dyeing, further reactions between the polymer and the dyestuff, the fiber and the dyestuff, and the fibre and the polymer and can be expeeted to take plaee, forming crosslink within the fibers. 

A facile preparation of the composites composed of cellulose and the polyacrylate-type polymeric ionic liquids was carried out by the in-situ polymerization of the polymerizable ionic liquids [66]. Ionic liquids, 2a and 2b were prepared by the reaction of 3-bromopropyl acrylate with 1-methylimidazole and 1-vinylimidazole which had one polymerizable group (acrylate) and two polymerizable groups (acrylate and vinyl) respectively. First, the pretreatment of cellulose in the mixtures of the two ionic liquids were performed, resulting in disruption of most of the crystalline structure of cellulose. Then, the radical polymerization of the ionic liquids in the pretreated mixtures was carried out by AIBN to obtain the composites, shown in Figure 5.15. 

Surface pretreatment of cellulosic fibers, processing timeand temperature of cellulose-containing polypropylene [153]... 

Uses Multifunctional prod, for pretreatment of cellulosics and its blends in exhaust applies. peroxide stabilizer to protect goods from alkali earth and transition metal catalytic damage rapid wetting agent wax/oil emulsifier disperses impurities in goods reduces scale deposition on equip. 

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