Cellulose Degradation, oxidative

For the oxidative pyrolysis (pyrolysis in the presence of oxygen around 100° C to 150° C, namely below the ignition temperature), it was shown that in contrast to cellulose, substituted celluloses degrade oxidatively [23a]. This was evaluated in more depth for ethyl cellulose [51]. The reaction starts probably with the initiation step at the free aldehyde groups ... 

The author is unaware of any commerical polymers that are specifically designed to degrade oxidatively, although oxidation may be involved in association with hydrolytic and biological degradation. It may be of interest to note that before World War II products known as rubbones were produced by degrading natural rubber with cobalt linoleate in the presence of cellulosic materials to produce low molecular weight, fluid oxidised natural rubber (Section 30.4). 

Recently, we have shown that non-isothermal chemiluminescence measurements for oxidized cellulose provide the same rate constants of cellulose degradation as may be measured from experiments on the decay of polymerization degree determined by viscometry. This may be also taken as indirect evidence that the light emission is somehow linked with the scission of polymer chains [29]. 

New International Dictionary, Merriam Co, Springfield, Mass(195I), 73 Alperox C. Trade name for tech lauroyl peroxide manufd by the Lucidol Division of Wallace Tieraan, Inc, Buffalo, NY Alpha-Cellulose is that portion of cellulosic materialfpulp, paper, etc) which,after treatment with 17,5% NaOH(mercerized strength) at 20° and diln to 7.3% NaOH,can be separated by filtration. The residue of alpha-cellulose is a good index of the undegraded cellulose content of the material. The alkali treatment removes degraded(oxidized or hydrolyzed) cellulose and short chain material. Some pentosans and hexosans may... 

Other compounds that we should consider are those derived from ligno-cellulose. Production of LMW components during oxidation of lignin, a biopolymer found only in terrestrial plants, may be quite high in fresh-waters where the input of ligno-cellulose and other allochthonous DOM is substantial (see Chapter 2). But we know little about LMW byproducts from ligno-cellulose degradation (Benner and Hodson, 1985 Moran and Hodson, 1989). 

The oxidative power of carbanilation mixtures containing DMSO and isocyanates was concluded from cellulose degradation in these mixtures. The mechanism of cellulose degradation was proposed to be a combination of oxidation and subsequent chain cleavage at the oxidized positions according to a /3-elimination mechanism triggered by auxiliary bases [ 106]. 

DMSO/isocyanate carbanilation medium on cellulose. It should be noted that the oxidation per se does not cause chain cleavage and cellulose degradation, but only the introduction of carbonyl functionalities along the cellulose chain. However, these groups constitute points of pronounced chemical instability where subsequent cleavage, mainly under basic conditions in /(-elimination processes, will readily occur. 

While there is controversy as to whether or not this Cellulose species exists, experimental evidence for the Cellulose species was obtained by Price et al.,60 who suggested that it could be a free radical in nature. At lower temperatures, oxygen plays a dominant role in cellulose degradation, and pyrolysis is faster in an oxidative atmosphere than in an inert one.61 Oxygen catalyzes the formation of both volatiles and char-promoting reactions.62 At higher temperatures, the degradation products are little affected.61... 

Nutt, A. 2006. Hydrolytic and Oxidative Mechanisms Involved in Cellulose Degradation. Uppsala University Digital Comprehensive Summaries of Uppsala Dissertations from the faculty of Science and Technology (Ph. D. thesis), 185,51 pages. 

Excess base is used to ensure that the pH is kept at or below 12, to ensure that hypochlorite, OCl (and not hypochlorous acid, HOCl), is the bleach active species (see Fig. 15.10), and to stabilize the hypochlorite ion for this purpose. Both the C and H, stages are designed to operate at pHs well clear of neutral to minimize the concentration of undissociated hypochlorous acid and attendant cellulose degradation. Hypochlorite ion is a less powerful oxidant than chlorine and hence more suitable for later bleach stages. Hypochlorite oxidizes and dissolves the chlorinated residues from the chlorination stage, the so-called... 

Cellobiose Oxidases. — A recently discovered oxidative enzyme of importance in in vitro cellulose degradation seems to be a cellobiose oxidase. The contribution of this enzyme to the degradation has been discussed in a review of cellulose enzymolysis. 

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