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

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.

Kinetics of a thermooxidative degradation of polyethylene: Fractal analysis

2004 ◽  
Vol 93 (5) ◽  
pp. 2348-2351 ◽  
Author(s):  
G. V. Kozlov ◽  
G. B. Shustov ◽  
G. E. Zaikov
Keyword(s):  
Fractal Analysis ◽  
Thermooxidative Degradation ◽  
Kinetics Of

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.

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.

Heterogeneity of Cerebral Blood Flow: a Fractal Approach

2000 ◽  
Vol 39 (02) ◽  
pp. 37-42 ◽  
Author(s):  
P. Hartikainen ◽  
J. T. Kuikka
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Fractal Dimension ◽  
Frontal Lobe ◽  
Fractal Analysis ◽  
Relative Dispersion ◽  
Emission Computed Tomography ◽  
Brain Blood Flow ◽  
Healthy Controls ◽  
Fractal Approach

Summary Aim: We demonstrate the heterogeneity of regional cerebral blood flow using a fractal approach and singlephoton emission computed tomography (SPECT). Method: Tc-99m-labelled ethylcysteine dimer was injected intravenously in 10 healthy controls and in 10 patients with dementia of frontal lobe type. The head was imaged with a gamma camera and transaxial, sagittal and coronal slices were reconstructed. Two hundred fifty-six symmetrical regions of interest (ROIs) were drawn onto each hemisphere of functioning brain matter. Fractal analysis was used to examine the spatial heterogeneity of blood flow as a function of the number of ROIs. Results: Relative dispersion (= coefficient of variation of the regional flows) was fractal-like in healthy subjects and could be characterized by a fractal dimension of 1.17 ± 0.05 (mean ± SD) for the left hemisphere and 1.15 ± 0.04 for the right hemisphere, respectively. The fractal dimension of 1.0 reflects completely homogeneous blood flow and 1.5 indicates a random blood flow distribution. Patients with dementia of frontal lobe type had a significantly lower fractal dimension of 1.04 ± 0.03 than in healthy controls. Conclusion: Within the limits of spatial resolution of SPECT, the heterogeneity of brain blood flow is well characterized by a fractal dimension. Fractal analysis may help brain scientists to assess age-, sex- and laterality-related anatomic and physiological changes of brain blood flow and possibly to improve precision of diagnostic information available for patient care.

Air Pollution Attributable Deaths: A Global View Through Fractal Analysis

2014 ◽  
Vol 2 (1) ◽  
pp. 149-162
Author(s):  
Melvin de Castro ◽  
◽  
Tonette Villanueva ◽  
Grace Arcamo ◽  
Rayna Lynn de Castro ◽  
...  
Keyword(s):  
Air Pollution ◽  
Fractal Analysis ◽  
Global View
Sign in / Sign up

Export Citation Format

Share Document