Estimation of the oxygen-limiting amount consumed by polymeric melt in the thermooxidative degradation process

2004 ◽  
Vol 92 (5) ◽  
pp. 2840-2844
Author(s):  
G. V. Kozlov ◽  
G. B. Shustov ◽  
G. E. Zaikov
Keyword(s):  
Degradation Process ◽  
Thermooxidative Degradation

Studies of thermooxidative degradation process of chlorinated natural rubber from latex

2004 ◽  
Vol 410 (1-2) ◽  
pp. 119-124 ◽  
Author(s):  
He-ping Yu ◽  
Si-dong Li ◽  
Jie-ping Zhong ◽  
Kui Xu
Keyword(s):  
Natural Rubber ◽  
Degradation Process ◽  
Thermooxidative Degradation

Study on Thermooxidative Degradation of Poly(Vinyl Alcohol)/Silica Nanocomposite Prepared with SAM Technique

2005 ◽  
Vol 23 ◽  
pp. 375-378 ◽  
Author(s):  
Zheng Peng ◽  
Ling Xue Kong ◽  
Si Dong Li
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Self Assembly ◽  
Vinyl Alcohol ◽  
Fourier Transform Infrared ◽  
Degradation Process ◽  
Poly Vinyl Alcohol ◽  
Thermooxidative Degradation ◽  
Thermooxidative Stability

The thermooxidative degradation of poly (vinyl alcohol)/silica (PVA/SiO2) nanocomposite prepared with self-assembly monolayer (SAM) technique is investigated by using a thermogravimetry (TG) and Fourier transform infrared spectroscopy coupled thermogravimetry (FTIR/TG). The results show that although the thermooxidative degradation process of prepared nanocomposite is similar to that of the pure PVA, its thermooxidative stability has been greatly improved.

Thermooxidative degradation and its kinetics of natural rubber coagulated by microwave radiation

2012 ◽  
Vol 32 (8-9) ◽  
pp. 511-517 ◽  
Author(s):  
Lu-Sheng Liao ◽  
Jian-He Liao ◽  
Yi-Min Li ◽  
Yong-Ping Chen ◽  
Yan-Fang Zhao ◽  
...  
Keyword(s):  
Activation Energy ◽  
Kinetic Model ◽  
Natural Rubber ◽  
Microwave Radiation ◽  
Preexponential Factor ◽  
Degradation Process ◽  
Main Stage ◽  
Thermooxidative Degradation ◽  
Mean Values ◽  
One Step

Abstract The thermooxidative degradation of natural rubber (NR) coagulated by microwave radiation (NR-m) was investigated by thermogravimetry (TG) analysis, and compared with NR coagulated by acid (NR-a). It was found that the degradation process is not a one-step reaction, the main degradation process occurs at 300–400ºC, and the equilibrium degradation temperatures of NR-m are higher than those of NR-a. Different methods were used to find the most probable kinetic model and the Arrhenius para­meters (activation energy E and preexponential factor A) for the main stage of thermooxidative degradation of NR-m. The results show that the values of E and A, obtained from the Coats-Redfern method, are highly variable with the kinetic model chosen and the heating rate (β), and the apparent activation energy (E0) when β approaches zero for the Dn type kinetic model is in the range of 96.7–106.4 kJ ∙ mol-1. The mean values of E, calculated by the Friedman and Flynn-Wall-Ozawa (FWO) methods, are 113.8 and 83.3 kJ ∙ mol-1, respectively, suggesting E in the range of 83.3–113.8 kJ ∙ mol-1. Comparison of these two ranges indicates the most probable kinetic model to be Dn type kinetic models, corresponding to a diffusion-controlled mechanism.

Fractal analysis of thermooxidative degradation process of polymeric melts

2003 ◽  
Vol 89 (9) ◽  
pp. 2378-2381 ◽  
Author(s):  
G. V. Kozlov ◽  
G. B. Shustov ◽  
G. E. Zaikov
Keyword(s):  
Fractal Analysis ◽  
Degradation Process ◽  
Thermooxidative Degradation

Techniques For The Preparation of Tissue Samples Containing Injectable Polymer Microcapsules

1985 ◽  
Vol 43 ◽  
pp. 710-711
Author(s):  
G.E. Visscher ◽  
R. L. Robison ◽  
G. J. Argentieri
Keyword(s):  
Drug Delivery ◽  
Drug Delivery Systems ◽  
Gastrocnemius Muscle ◽  
Degradation Process ◽  
Delivery Systems ◽  
Tissue Reaction ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
Injectable Polymer ◽  
Microscopic Techniques

The use of various bioerodable polymers as drug delivery systems has gained considerable interest in recent years. Among some of the shapes used as delivery systems are films, rods and microcapsules. The work presented here will deal with the techniques we have utilized for the analysis of the tissue reaction to and actual biodegradation of injectable microcapsules. This work has utilized light microscopic (LM), transmission (TEM) and scanning (SEM) electron microscopic techniques. The design of our studies has utilized methodology that would; 1. best characterize the actual degradation process without artifacts introduced by fixation procedures and 2. allow for reproducible results.In our studies, the gastrocnemius muscle of the rat was chosen as the injection site. Prior to the injection of microcapsules the skin above the sites was shaved and tattooed for later recognition and recovery. 1.0 cc syringes were loaded with the desired quantity of microcapsules and the vehicle (0.5% hydroxypropylmethycellulose) drawn up. The syringes were agitated to suspend the microcapsules in the injection vehicle.

Anaerobic Semi-Continuous Culture Biodegradation of Dichlorophenols Containing an Ortho Chlorine

1987 ◽  
Vol 22 (3) ◽  
pp. 427-436 ◽  
Author(s):  
S.E. Hrudey ◽  
E. Knettig ◽  
P.M. Fedorak ◽  
S.A. Daignault
Keyword(s):  
Activated Carbon ◽  
Continuous Culture ◽  
Chlorine Atom ◽  
Degradation Process ◽  
Anaerobic Sludge ◽  
Continuous Cultures ◽  
Complete Mineralization

Abstract Rapid and preferential dechlorination of the ortho chlorine from 2,6-, 2,4- and 2,3- dichlorophenol substrates was observed in semi-continuous cultures inoculated with 50% unacclimated anaerobic sludge. The rate of further dechlorination depended on the position of the second chlorine atom. The dechlorination rates for the second chlorine ranked ortho > para > meta. Complete mineralization to methane was only observed in cultures fed 2,6-dichlorophenol. Addition of activated carbon to the anaerobic cultures showed some benefit to the degradation process.

Examination for Degradation Paths of Butyltin Compounds in Natural Waters

1992 ◽  
Vol 25 (11) ◽  
pp. 117-124 ◽  
Author(s):  
N. Watanabe ◽  
S. Sakai ◽  
H. Takatsuki
Keyword(s):  
Glass Fiber ◽  
Half Life ◽  
Natural Waters ◽  
Sea Water ◽  
Degradation Process ◽  
Distilled Water ◽  
Degradation Rates ◽  
Clean Area ◽  
Butyltin Compounds ◽  
Sun Light

Examination of individual degradation paths (biodegradation and photolysis) of butyltin compounds (especially tributyltin: TBT) in natural waters was performed. Biodegradation of TBT and dibutyltin (DBT) in an unfiltered sea water in summer is rather fast; their half life is about a week. But pretreatment with glass fiber filter makes the half life of TBT much longer (about 80 days). Photolysis of TBT in sea water by sun light is rapid (half life is about 0.5 days), and faster than in distilled water or in fresh water. Degradation rates of each process for TBT are calculated in various conditions of sea water, and contribution rates are compared. Biodegradation will be the main degradation process in an “SS-rich” area such as a marina, but photolysis will exceed that in a “clean” area. Over all half lives of TBT in sea water vary from 6 days to 127 days considering seasons and presence of SS.

Surface charge and extracellular polymer of sludge in the anaerobic degradation process

1996 ◽  
Vol 34 (5-6) ◽  
pp. 309-316 ◽  
Author(s):  
X. S. Jia ◽  
Herbert H. P. Fang ◽  
H. Furumai
Keyword(s):  
Surface Charge ◽  
Growth Phase ◽  
Anaerobic Degradation ◽  
Degradation Process ◽  
Anaerobic Sludge ◽  
Batch Experiments ◽  
High Substrate Concentration ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Extracellular Polymer

Changes of surface charge and extracellular polymer (ECP) content were investigated in batch experiments for three anaerobic sludges, each of which had been enriched at 35°C and pH 639-7.3 for more than 40 batches using propionate, butyrate and glucose, individually, as the sole substrate. Results showed that both ECP and the negative surface charge were dependent on the growth phase of microorganisms. They increased at the beginning of all batches when the microorganisms were in the prolific-growth phase, having high substrate concentration and food-to-microorganisms ratio. Both later gradually returned to their initial levels when the microorganisms were in the declined-growth phase, as the substrate became depleted. The negative surface charge increased linearly with the total-ECP content in all series with slopes of 0.0187, 0.0212 and 0.0157 meq/mg-total-ECP for sludge degrading propionate, butyrate and glucose, respectively. The change of surface charge for the first two sludges was mainly due to the increase of proteinaceous fraction of ECP; but, for glucose-degrading sludge, that could be due to the increases of both proteinaceous and carbohydrate fractions of ECP. The negative-charged nature of anaerobic sludge implies that cations should be able to promote granulation of anaerobic sludge.

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