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.

Flow Phenomena in Rubber. I. Flow Curves for Natural Rubber

1949 ◽  
Vol 22 (2) ◽  
pp. 333-341 ◽  
Author(s):  
D. W. Saundeks ◽  
L. R. G. Treloar
Keyword(s):  
Natural Rubber ◽  
Temperature Dependence ◽  
Energy Of Activation ◽  
Flow Curves ◽  
Flow Process ◽  
A Value ◽  
Flow Phenomena

Abstract From the flow curves, the readings to be expected in the standard (shearing-disc) Mooney viscometer were calculated. These differ from the observed figures by about 15 per cent. The temperature dependence of the rate of flow is accounted for on the basis of the simple Eyring formula, and a value of 8.1 k. calorie per mole was obtained for the energy of activation involved in the flow process.

scholarly journals The kinetics of mutarotation in solution

1940 ◽  
Vol 176 (966) ◽  
pp. 352-367 ◽  
Keyword(s):  
Aqueous Solution ◽  
Room Temperature ◽  
Reducing Sugars ◽  
Arrhenius Equation ◽  
Energy Of Activation ◽  
A Value ◽  
Temperature Ranges ◽  
Velocity Coefficient ◽  
Kinetics Of ◽  
True Energy

The kinetics of the mutarotation of representative reducing sugars from the pentose, hexose and disaccharide series have been investigated polarimetrically over wide temperature ranges in aqueous solution. The dependence of the velocity coefficient, k , upon temperature is fairly well reproduced by an equation of the form ln k = C + ( J/R ) ln T - E/RT . The true energy of activation, E , is found to be some 6000 calories greater than the apparent value afforded by the Arrhenius equation at room temperature. J/R has a value of — 10, which is identified as the number of oscillators contributing to the activation. The constants C, J and E of this equation are discussed, with reference to many reactions, in terms of a theory of unimolecular reactions in solution.

Use of Sol-Gel Analysis to Estimate Chain Scission during Vulcanization. II. Peroxide Vulcanization of Synthetic cis-Polyisoprene

1965 ◽  
Vol 38 (2) ◽  
pp. 367-369
Author(s):  
G. M. Bristow
Keyword(s):  
Natural Rubber ◽  
Sol Gel ◽  
Chain Scission ◽  
A Value

Abstract Sol-gel analysis indicates that in the vulcanization of synthetic cis-polyisoprene by cumyl peroxide there are only 2–3 sites of scission per 100 crosslinked isoprene units, a value closely comparable with that observed for natural rubber.

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.

Copolymerization of 2,3:4,5-Di-O-isopropylidene-1-vinylbenzyl-β-D-fructopyranose with styrene: Preparation of polymers containing carbohydrate side chain residues and effect of composition on glass transition temperatures

1978 ◽  
Vol 31 (11) ◽  
pp. 2559 ◽  
Author(s):  
WK Busfield ◽  
FP Franke ◽  
RD Guthrie
Keyword(s):  
Glass Transition ◽  
Specific Rotation ◽  
Solution Viscosity ◽  
Side Chain ◽  
Transition Temperatures ◽  
Radical Initiation ◽  
Glass Transition Temperatures ◽  
A Value ◽  
Free Radical Initiation ◽  
Styrene Content

A range of copolymers of styrene and 2,3:4,5-di-O-isopropylidene-1- vinylbenzyl-β-D-fructopyranose (A) were prepared by free-radical initiation and characterized by i.r., N.M.R., microanalysis and solution viscosity. Reactivity ratios were derived. The specific rotation of the copolymers was linearly related to the molar composition. The glass transition temperatures of the copolymers decreased almost linearly with decreasing styrene content to a value of 73°C for the homopolymer of monomer (A). A method of releasing the isopropylidene blocking groups was developed; the glass transition temperatures of the resultant fructopyranose copolymers increased with decreasing styrene content to a value of 132°C for a copolymer containing 45 mole % styrene.

Derivatives of Synthetic Rubber

1944 ◽  
Vol 17 (4) ◽  
pp. 903-912 ◽  
Author(s):  
Herbert A. Endres
Keyword(s):  
Natural Rubber ◽  
Moisture Absorption ◽  
Lower Solution ◽  
Solution Viscosity ◽  
Vapor Transfer ◽  
Synthetic Rubber ◽  
Commercially Important ◽  
Synthetic Derivatives ◽  
Derivatives Of ◽  
Selection Of

Abstract By processes of cyclization and chlorination, synthetic elastomers can be converted into derivatives which differ from the parent product in the following respects: 1. Higher specific gravity. 2. Higher softening point. 3. Greater hardness and rigidity. 4. Less flexibility and elongation. 5. Greater chemical resistance. 6. Lower solution-viscosity. 7. Lower moisture-vapor transfer. 8. Lower moisture absorption. 9. Less tackiness. 10. Greater solubility in polar solvents. Thus, many of the desirable features of the commercially important derivatives of natural rubber can be duplicated in synthetic products. It is, furthermore, logical to assume that the field of usefulness of synthetic derivatives will be extended by selection of the proper type of synthetic rubber for cyclization, chlorination, and hydrochlorination to bring out certain desirable characteristics which are not inherent in products made from natural rubber.

Preparation of Functionalized Low Molecular Weight Natural Rubber Latex Using Solid Nanometric TiO3 Film as a Photocatalyst

2005 ◽  
Vol 78 (4) ◽  
pp. 597-605 ◽  
Author(s):  
Jitladdat Sakdapipanich ◽  
Patjaree Suksawad ◽  
Kittipong Insom ◽  
Seiichi Kawahara
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Uv Irradiation ◽  
Tio2 Film ◽  
Uv Light ◽  
Average Molecular Weight ◽  
Natural Rubber Latex ◽  
Petri Dish ◽  
Solution Viscosity ◽  
Photochemical Degradation

Abstract Natural rubber (NR) is a high molecular weight (MW) hydrophobic polymer, which can not be easily dissolved in several kinds of solvents, leading to the limitation of usage. NR latex containing low MW and reactive-terminal groups is another interesting form to extend the applications of NR. In this study, a photochemical degradation of NR using H2O2, nanometric TiO2 film and UV irradiation was applied to prepare the hydroxylated low MW NR (LNR). A solid nanometric TiO2 film prepared from titanium solution was applied in the present work. The photosensitivity of the self-assembled TiO2 film was determined by the decomposition rate of methylene blue stock solution using UV/VIS spectrophotometer. The effect of type of NR latex used, H2O2, UV light and TiO2 film on the molecular weight reduction was studied, based on change in intrinsic viscosity determined by Ubbelohde solution viscosity. The structural characterization of the resulting LNR was analyzed by FT-IR and NMR techniques. It was found that hydroxylated LNR with number average molecular weight of 1 × 104 g/mol was obtained by UV irradiation (40 W) of deproteinized natural rubber (DPNR) latex (10% DRC) containing 30% w/w H2O2, on a petri dish coated with TiO2 film for 5 hr. The advantage of this method is that the obtained hydroxylated LNR in either latex or dry rubber form is very clean without further purification.

Utilization of Metroxylan sagu Pith Waste as Biodegradable Filler for Natural Rubber (NR) Latex Films

2017 ◽  
Vol 264 ◽  
pp. 198-201 ◽  
Author(s):  
A. Rashid Azura ◽  
Nuraiffa Syazwi Adzami ◽  
Husnul A. Tajarudin
Keyword(s):  
Natural Resources ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Agricultural Waste ◽  
Value Added ◽  
Extraction Process ◽  
Sem Analysis ◽  
Sago Starch ◽  
Latex Films ◽  
A Value

Utilization of agricultural waste toward sustainability has increase a value-added product from a natural resources nowadays. Metroxylan sagu pith waste (MSPW) is a residue from starch extraction process. This research aim to investigate the potential of MSPW as a biodegradable fillers to replace sago starch in Natural Rubber (NR) latex films. The MSPW flour is characterized and compared with sago starch. Results shown MSPW has almost similar properties with sago starch with high content of starch (60%) and moisture (80%). Spectra of MSPW and Sago Starch (SS) are very closed to one another due to the similarity of functional groups. SS has granular shape while MSPW has irregular shape under SEM analysis. The addition of MSPW shown slightly lower tensile properties and tear strength as compared to SS but still within the acceptable value. Thus, MSPW has high potiential to replace SS as biodegradable fillers in NR latex films.

Sign in / Sign up

Export Citation Format

Share Document