Cellulose acid degradation

Urea—Phosphate Type. Phosphoric acid imparts flame resistance to ceUulose (16,17), but acid degradation accompanies this process. This degradation can be minimized by iacorporation of urea [57-13-6]. Ph osph oryl a ting agents for ceUulose iaclude ammonium phosphate [7783-28-0] urea—phosphoric acid, phosphoms trichloride [7719-12-2] and oxychloride [10025-87-3] monophenyl phosphate [701-64-4] phosphoms pentoxide [1314-56-3] and the chlorides of partiaUy esterified phosphoric acids (see Cellulose esters, inorganic). 

HEC hydroxyethyl cellulose nonionic 110 viscosity builder, acid degradable primarily for completion/workover fluids... 

Hydroxyethyl cellulose (HEC), a nonionic thickening agent, is prepared from alkali cellulose and ethylene oxide in the presence of isopropyl alcohol (46). HEC is used in drilling muds, but more commonly in completion fluids where its acid-degradable nature is advantageous. Magnesium oxide stabilizes the viscosity-building action of HEC in salt brines up to 135°C (47). HEC concentrations are ca 0.6—6 kg/m (0.2—21b/bbl). 

Cellulose sulfated usiag sulfamic acid degrades less than if sulfated usiag sulfuric acid (23). Cellulose esters of sulfamic acids are formed by the reaction of sulfamyl haHdes ia the presence of tertiary organic bases (see Cellulose esters). 

One of the most industrially important characteristics of papers is their chemical stability, which enables them to withstand degradation with its consequential loss of tensile and tear strength and fold endurance under normal conditions of use. However, this stability is not absolute. Cellulose is susceptible to oxidation and the glycosidic linkage is susceptible to hydrolysis. In order to protect book papers from acid degradation, they must not be exposed to acid. Acids are generated from the alum-rosin size as well as from such... 

Figure 5 Rate of weight loss in acidic degradation of a-cellulose in 2 M and 4 M HCI at 90°C. (From Ref. 126.)...

Figure 6 Rate of DP reduction in acidic degradation of cotton cellulose in 1 M HCI at 50 C. (From Ref. 122.)...

Consistent with the behavior of simple glycosides (Table 2), the homogeneous hydrolysis rate of B-(l-4)-linked polysaccharides, as BeMiller summarized [255, 256], increased in the order cellulose (1) < mannan (2-2.5) < xylan (60-80) < galactan (300). This further demonstrates the significant role of accessibility in acidic degradation reactions. 

As we have indicated above, the ageing of fibres like flax often results in the formation of acidic degradation products. These, together with adsorbed acidic atmospheric pollutants, can continue to promote further damage through the hydrolytic depolymerisation of cellulose. So, in relation to its stability, it seemed important to estimate the acid content of the Victory sailcloth. There are two approaches that can be taken surface measurements on the fabric and acid extractions. 

The principal commercial sources of chemical cellulose are purified cotton linters of about 99 per cent a-cellulose content and purified wood pulp of about 96 per cent cellulose content. Cellulose occurs in these materials as a fairly highly crystalline, high-molecular-weight polymer. It is in a fibrous form, which is insoluble in common reagents. Cellulose wUl not react to any significant d ee with acetic acid and will react with acetic anhydride without a catalyst only at very high temperatures, at which the cellulose is degraded. 

The acid degradation occurs in the amorphous or disordered regions of cellulose (admittedly some removal occurs on the surfece of the crystallites but this does not result in a change in D.P.) Cleavage of the cellulose chain, in the amorphous or disordered... 

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