Studies on Microbial Degradation of Natural Rubber Using Dilute Solution Viscosity Measurement and Weight Loss Techniques

2012 ◽  
Vol 1 (2) ◽  
pp. 434-446 ◽  
Author(s):  
G. N. Onyeagoro ◽  
◽  
E. G. Ohaeri ◽  
U. J. Timothy ◽  
◽  
...  
Keyword(s):  
Weight Loss ◽  
Natural Rubber ◽  
Microbial Degradation ◽  
Viscosity Measurement ◽  
Solution Viscosity ◽  
Dilute Solution

Air Permeability of Elastomers by Diffusion Tests

1954 ◽  
Vol 27 (4) ◽  
pp. 996-1004 ◽  
Author(s):  
M. Czuha
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Large Range ◽  
Air Permeability ◽  
Solution Viscosity ◽  
Dilute Solution ◽  
Slight Effect ◽  
Structural Modifications ◽  
Styrene Copolymers ◽  
Mooney Viscosity

Abstract The permeability of various tread compounds to air was measured in a modified Warburg diffusion apparatus. Measurements were made at 30° C, with air applied at 48 psi. pressure, on molded disks approximately 0.025 inch thick and an area of 12.57 sq. in. The tests were reproducible within 4 per cent on control specimens. The compounds investigated showed permeabilities intermediate between the low values for Butyl and the high values for natural rubber. The permeability decreased with increasing combined styrene contents and with a decrease of temperature of polymerization for polybutadiene and low-styrene copolymers. It was unaffected by variation over a large range in polymer Mooney viscosity, gel content, and dilute-solution viscosity. A slight and almost linear decrease of permeability was found with increases in time of cure and carbon black loading for the stocks. In terms of the 300 per cent modulus, an increase of 100 psi. was accompanied by a 2 per cent decrease in permeability. Processing oil in the polymer had only a slight effect on permeability, when compared to the effects of compositional and structural modifications. Alfin and sodium, 75/25 BD/S, copolymers showed the lowest air permeability of the tread type of compounds that were studied.

Effects of Molecular Weight of Chitosan on the Biodegradability and Thermal Properties of Polybutylene Succinate/Chitosan Composites

2018 ◽  
Vol 775 ◽  
pp. 26-31
Author(s):  
Sukantika Manatsittipan ◽  
Kamonthip Kuttiyawong ◽  
Kazuo Ito ◽  
Sunan Tiptipakorn
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Thermal Properties ◽  
Water Absorption ◽  
Melting Temperature ◽  
Microbial Degradation ◽  
Decomposition Temperature ◽  
Molecular Weights ◽  
Significant Difference ◽  
Polybutylene Succinate

In this study, the biodegradability and thermal properties the composites of polybutylene succinate (PBS) and chitosan of different molecular weights (Mn = 104,105, and 106 Da) were prepared at chitosan contents of 0-10 wt%. After 10 days of microbial degradation, the results show that the amount of holes from degradation was increased with either decreasing Mn or increasing chitosan contents. However, the size of holes was increased with increasing Mn and chitosan contents. The results from Differential Scanning Calorimeter (DSC) present that the melting temperature (Tm) of PBS was decreased with increasing chitosan contents. Moreover, there was no significant difference between Tm of the composites with different Mn of chitosan. From the TGA thermograms, the decomposition temperature at 10% weight loss (Td10) was decreased with increasing chitosan contents. Moreover, the water absorption of PBS/chitosan composites was increased with increasing Mn and content of chitosan.

PROTON MAGNETIC RESONANCE LINE WIDTH AS A FUNCTION OF POLYMER TACTICITY

1966 ◽  
Vol 44 (2) ◽  
pp. 153-156 ◽  
Author(s):  
S. Brownstein ◽  
D. M. Wiles
Keyword(s):  
Magnetic Resonance ◽  
Methyl Methacrylate ◽  
Proton Magnetic Resonance ◽  
Chloroform Solution ◽  
Spin Coupling ◽  
Solution Viscosity ◽  
Dilute Solution ◽  
Poly Methyl Methacrylate ◽  
Resonance Line Width ◽  
Polymer Tacticity

The high resolution proton magnetic resonance spectra of five samples of poly(methyl methacrylate) in chloroform solution have been measured with 100 Mc/s equipment. The widths of the absorption lines arising from the protons of the α-methyl and the methoxyl groups have been compared. The widths are greater when the polymer is predominantly syndiotactic than when it is predominantly isotactic. It is concluded that isotactic samples have the more extended conformation in chloroform solution. An analogy with dilute solution viscosity measurements is outlined in support of this conclusion. Differences between the widths of the lines of the methylene protons in a completely isotactic poly(methyl methacrylate) sample are attributed to long range spin coupling.

scholarly journals Synthesis, Characterization, and Biodegradation Studies of Poly(1,4-cyclohexanedimethylene-adipate-carbonate)s

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Ajay S. Chandure ◽  
Ganesh S. Bhusari ◽  
Suresh S. Umare
Keyword(s):  
Weight Loss ◽  
Enzymatic Degradation ◽  
Hydrolytic Degradation ◽  
Phosphate Buffer Solution ◽  
Film Surface ◽  
Solution Viscosity ◽  
Buffer Solution ◽  
Sem Images ◽  
Titanium Butoxide ◽  
Soil Burial

Aliphatic/alicyclic poly(1,4-cyclohexanedimethylene-adipate-carbonate)s (PCACs) were synthesized by a transesterification from 1,4-cyclohexamethylendimethanol (1,4-CHDM), adipic acid (AA), diethyl carbonate (DEC), and titanium butoxide Ti(OBu)4 as a transesterification catalyst. The synthesized PCACs were characterized by the Fourier transform infrared (FTIR), X-ray diffraction analysis (XRD), solubility, solution viscosity, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscope (SEM) for their structural, physical, thermal, and morphological investigation. The structure of synthesized PCACs was confirmed by FTIR. All TGA curves of PCACs shows 10% weight loss above 270°C, and they reveal good thermal stability. Biodegradability of PCACs was investigated by hydrolytic degradation at (pH 7.2 and 11.5), enzymatic degradation using Rhizopus delemar lips at 37°C in phosphate buffer solution (PBS), and soil burial degradation at 30°C. The hydrolytic degradation shows the greater rate of weight loss in PBS at pH-11.5 than pH-7.2. The hydrolytic and soil burial degradation shows faster rate of weight loss as compared to enzymatic degradation. Biodegradation rate of PCACs follows the order: PCAC-20 > PCAC-40 > PCAC-60. SEM images show that degradation occurred all over the film surface, creating holes and cracks. These biodegradable PCACs may be able to replace conventional polymer in the fabrication of packaging film in near future.

THE CONCENTRATED SOLUTION VISCOSITY OF GR-S: ITS VARIATION (IN BENZENE) WITH TEMPERATURE AND CONCENTRATION

1948 ◽  
Vol 26b (8) ◽  
pp. 551-563 ◽  
Author(s):  
L. H. Cragg ◽  
L. M. Faichney ◽  
H. F. Olds
Keyword(s):  
Natural Rubber ◽  
Energy Of Activation ◽  
Solution Viscosity ◽  
A Value ◽  
Concentrated Solution

With a falling ball viscometer, measurements of the viscosity of solutions of GR–S in benzene have been made at very low rates of shear, at concentrations ranging from 10 to 19%, and at temperatures ranging from 10° to 35 °C. Within these limits, the viscosity of a solution of GR–S in benzene is given by the equation [Formula: see text]. Extrapolation, by means of this equation, to 100% polymer yields a value of 13.0 kcal. per mole for the energy of activation of flow of GR–S; this value, though of dubious antecedence, is yet of interest because it approximates that expected for GR–S on the basis of the behavior of such polymers as natural rubber and polystyrene.

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