Chain-length degradation

The initial rate of chain-length degradation AS/At, with S = 1/DP (Table II), increased, of course, with degradation temperature, both in the thermal and the thermohydrolytic treatments of the linters, but the Arrhenius energy of activation was much lower in thermohydrolysis. The difference in the rate between both kinds of treatment decreased significantly after a decrystallizing pretreatment of the linters with liquid... 

Table III. Chain-length Degradation of Different Cellulose Samples at 100°C in Aqueous Media...

Acid hydrolysis of these samples led to the results to be expected, i.e., a lowering of LODP and residue value by NH3 pretreatment and mercerization as well as by mechanical disintegration prior to the hydrolytic treatment (Table XII). With regard to residue value, an NH3 pretreatment again proved to be more efficient in enhancing accessibility than a mercerization, while the rate constant of chain-length degradation was increased somewhat more by mercerization. 

Yields of sulfonyl fluorides prepared by ECF vary depending on the particular stmcture. Chain degradation becomes more important as the chain length kicreases (6). Yields can vary from 96% for perfluoromethanesulfonyl fluoride (7) to 43—50% for perfluorooctanesulfonyl fluoride (8). Trifluoromethanesulfonic acid can be prepared via trifluoromethanesulfenyl chloride as shown ki equations 5—7 (9). 

Environmental. In general, chlorinated paraffins biodegrade the rate is determined by chlorine content and carbon chain length. Microorganisms previously acclimatized to specific chlorinated paraffins show a greater ability to degrade the compounds than nonacclimatized organisms. Mammals and fish have been shown to metabolize chlorinated paraffins (8). 

As a result of the en2ymatic degradation of proteins, key indexes change, ie, protein solubiUty indexes (PSI), peptide chain length (PCL), and protein solubihty in 0.8 Af TCA (TCA-index) (Fig. 14). Unpleasant bitterness was once a problem for some protein hydroly2ates. This problem can now be overcome by proper selection of the reaction parameters and the en2ymes used. 

Fig. 38. Action of entanglements in simple shear degradation. The tension on the qth link from the center is given by fq = f0(l — 4q2/n2), where f0 qsy f(L) is the tension on center link (f(L) = function of chain length) and n = number of links per chain.

In flow-induced degradation, K is strongly dependent on the chain length and on the fluid strain-rate (e). According to the rate theory of molecular fracture (Eqs. 70 and 73), the scission rate constant K can be described by the following equation [155]... 

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