Degradation rate

The use of degradation rates to determine the age of a contaminant plume assumes a contaminant from a single, slug-type release, which degrades to a more recalcitrant chemical compound (i.e., trichloroethene degrading to 1,2-dichloroethene), will enter the water table or aquifer at a point in time when none of the daughter product is present in the aquifer  

---

Polylactic Acid. Polylactic acid (PLA) was introduced in 1966 for degradable surgical implants. Hydrolysis yields lactic acid, a normal intermediate of carbohydrate metaboHsm (23). PolyglycoHc acid sutures have a predictable degradation rate which coincides with the healing sequence of natural tissues. 

Under approximately neutral conditions, where the degradation rate is independent of pH for a range of pH values characteristic of the individual penicillin, hydrolysis appears to occur through a general base-catalyzed attack of a water molecule (77JPS861) on the /3-lactam carbonyl. 

The beta-conidendrol is incorporated as an antioxidant and is frequently referred to in the patent literature, as is also di-P-naphthyl-p-phenylenediamine for this purpose. It is claimed that in the example given above the degradation rate at 222°C is only 0.09% per minute compared with typical values of 0.6-0.8% for unesterified polymer. 

Park and Skene [65] found that the effectiveness of the initiator end groups for causing dehydrochlorination was in the ratio lauroyl peroxide-isopropyl peroxidi-carbonate-benzoyl peroxide-azoisobutyronitrile = 9.7 5.8 4.4 1.6. These values were obtained at 220°C, and the degradation rates were taken as the mean value for 0-20% dehydrochlorination. 

Thermal stabilities of modified PVC samples acet-oxylated to varying degrees (reaction temperature 46°C) were determined [45]. Rate of thermal dehydrochlorination at 1% degradation was taken as a measure of thermal stability. The log of the degradation rate is plotted against the acetate content of the polymer in Fig. 2. 

Chain degradation in turbulent flow has been frequently reported in conjunction with drag reduction and in simple shear flow at high Reynolds numbers [187], Using poly(decyl methacrylate) under conditions of turbulent flow in a capillary tube, Muller and Klein observed that the hydrodynamic volume, [r ] M, is the determining factor for the degradation rate in various solvents and at various polymer concentrations [188], The initial MWD of the polymers used in their experiments are, however, too broad (Mw/Iiln = 5 ) to allow for a precise... 

High COD, BOD, and MBAS degradation rates of 90% were measured. 

Decay transients, photo electrodes and, 505 Degradation rate as a function of polarization time, 328 Degradation reactions simultaneous with electrode polymerization, 326 DeLevie on the density of broken bonds and the effect on the potential of zero charge, 75... 

This comprehensive article supplies details of a new catalytic process for the degradation of municipal waste plastics in a glass reactor. The degradation of plastics was carried out at atmospheric pressure and 410 degrees C in batch and continuous feed operation. The waste plastics and simulated mixed plastics are composed of polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile butadiene styrene, and polyethylene terephthalate. In the study, the degradation rate and yield of fuel oil recovery promoted by the use of silica alumina catalysts are compared with the non-catalytic thermal degradation. 9 refs. lAPAN... 

The degradation rate of P4HB is slower than that of PGA, but faster than PLEA, PCE, and some other PHAs, such as P3HB. P4HB are likely to undergo gradual changes in mechanical properties rather than the more. A remarkable improvement to develop the heart valve was achieved by... 

The objectives of the soil persistence experiments were (1) to learn the effect of soil type and concentration on the TCDD degradation rate, (2) to isolate and characterize degradation products from DCDD and TCDD, and (3) to determine whether chlorodioxins could be formed from chlorophenol condensation in the soil environment. This last study was essential since quality control at the manufacturing level could reduce or eliminate the formed dioxin impurity. But the biosynthesis of chlorodioxins by chlorophenol condensation in the soil environment could not be controlled and would have connotations for all chlorophenol-de-rived pesticides if formation did occur. The same question needed to be answered for photochemical condensation reactions leading to chloro-... 

---