CIS-1,4 Polyisoprene Prepared with Alkyl Aluminum and Titanium Tetrachloride

1958 ◽  
Vol 31 (4) ◽  
pp. 838-846 ◽  
Author(s):  
H. E. Adams ◽  
R. S. Stearns ◽  
W. A. Smith ◽  
J. L. Binder
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Room Temperature ◽  
Titanium Tetrachloride ◽  
Polymerization Temperature ◽  
Solution Polymerization ◽  
Lower Temperature ◽  
Hysteretic Properties

Abstract By adjustment of the relative amounts of the two components of the catalyst and the temperature of polymerization, cis-1,4 polyisoprene can be produced free from trans-1,4 configuration. Catalysts containing a mole ratio of alkyl aluminum to titanium tetrachloride of 1.0 produce polymers with this configuration at room temperature. At lower temperature of polymerization, somewhat higher ratios are needed to achieve the same result. Solution polymerization was used to control the reaction and obtain a uniform product. It was necessary to use 3 to 5 phm of total catalyst to obtain 100 per cent yield in 4 hours at room temperature. The inherent viscosity of the polymers made under these conditions is low, usually 2.0 to 2.5. However, higher molecular weight polymers are produced at lower polymerization temperature. Compounding studies indicate that vulcanizates of these polymers possess both normal and hot tensile properties comparable to natural rubber. Hysteretic properties of the carbon black vulcanizates of the polymers studied are inferior to those of natural rubber.

Tensile Properties of Natural and Synthetic Rubbers at Elevated and Subnormal Temperatures

1950 ◽  
Vol 23 (2) ◽  
pp. 338-346 ◽  
Author(s):  
B. S. T. T. Boonstra
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Carbon Black ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
High Temperature Strength ◽  
Synthetic Rubber ◽  
Natural And Synthetic

Abstract It is necessary to determine the physical properties of rubbers at relatively high temperatures when products made from them are to be used at such temperatures in actual service. The term heat aging is used when the vulcanizate is tested at room temperature, exposed to elevated temperatures for given periods of time, and then tested again at room temperature. The term high-temperature strength is proposed for values obtained when the vulcanizates are tested at the actual higher service temperatures. Effective comparison of natural and synthetic rubbers is best obtained by determining tensile product values, which are the result of the combining of tensile strength and elongation values. In the evaluating of vulcanizates of tire compounds of various rubbers, another factor must be taken into account. Synthetic-rubber tires develop more heat in service than do natural-rubber tires, and the former therefore generally operate at higher temperatures than do the latter. Synthetic-rubber tires therefore require a greater high temperature strength than do natural rubber tires, but, as has been shown, synthetic rubbers actually have a lower high-temperature strength. The part played by carbon black with respect to the tensile properties of some synthetic rubbers is considered that of a substitute for crystallization in natural and other synthetic rubbers, which substitute does not, however, possess the same favorable features. Carbon black even in noncrystallizing rubbers does not increase strength; it merely shifts the optimum strength value to a higher temperature so that this temperature is in the room temperature range. The temperature coefficient of strength for Butyl and Neoprene rubbers is so large at room temperature that a few degrees' difference in temperature causes large changes in strength. The tensile strength and elongation at break of these two rubbers decrease sharply between 20 and 40° C.

scholarly journals Cure characteristics, swelling behaviour and tensile properties of carbon black-filled Natural Rubber (NR)/Chloroprene Rubber (CR) blends in the presence of alkanolamide

2018 ◽  
Vol 197 ◽  
pp. 12005 ◽  
Author(s):  
Indra Surya ◽  
Mimpin Ginting ◽  
Hanafi Ismail
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Tensile Modulus ◽  
Palm Stearin ◽  
Swelling Behaviour ◽  
Blend Ratio ◽  
Elongation At Break ◽  
Cure Characteristics ◽  
Chloroprene Rubber

The cure characteristics, swelling behaviour and tensile properties of carbon black (CB)-filled natural rubber (NR)/chloroprene rubber (CR) blends in the presence of alkanolamide (ALK) were investigated. The NR/CR blends were prepared at 50/50 blend ratio. The ALK was prepared from Refined Bleached Deodorized Palm Stearin (RBDPS) and diethanolamine and added into the CB-filled NR/CR blends as a rubber additive. The ALK loadings were 0.0, 1.0, 3.0, 5.0 and 7.0 phr. It was found that the ALK exhibited shorter scorch and cure times and higher elongation at break of the CB-filled NR/CR blends. The ALK also exhibited higher torque differences, tensile modulus and tensile strength up to 5.0 phr of ALK and then decreased with further increases in the ALK loading. The swelling test proved that the 5.0 phr loading of ALK caused the highest degree in crosslink density of the CB-filled NR/CR blends.

Ozonolytic Degradation of Interpolymers of Natural Rubber with Methyl Methacrylate and Styrene

1958 ◽  
Vol 31 (1) ◽  
pp. 82-85
Author(s):  
D. Barnard
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Natural Rubber ◽  
Accurate Determination ◽  
Synthetic Polymers ◽  
Polymer Chains ◽  
Low Molecular Weight ◽  
Rubber Content ◽  
Tert Butyl Hydroperoxide

Abstract The preparation of graft and block interpolymers of natural rubber and synthetic polymers has made it desirable that the number and size of polymer chains attached to rubber be readily determinate. The degradation of unsaturated polymers with tert-butyl hydroperoxide in the presence of osmium tet oxide has been used for the determination of free polystyrene in SBR and carbon black in several elastomers, and has recently been applied to the present problem. The accurate determination of the rubber content of interpolymers by quantitative ozonolysis essentially according to the method of Boer and Kooyman suggested that this might be made the basis of isolation of the attached polymer, the rubber being degraded into fragments of low molecular weight, from which the polymer could be separated by conventional techniques. The method should be applicable to any interpolymer, or mixture, of a polyunsaturated and a saturated polymer and is illustrated with reference to interpolymers of natural rubber (NR)-polymethyl methacrylate (PMM) and NR-polystyrene (PS).

An HF-Nickel-R3Al Catalyst System for Producing High Cis-1,4-Polybutadiene

1972 ◽  
Vol 45 (1) ◽  
pp. 268-277 ◽  
Author(s):  
M. C. Throckmorton ◽  
F. S. Farson
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
High Molecular Weight ◽  
Catalyst Concentration ◽  
Dynamic Properties ◽  
Catalyst System ◽  
Polymerization Temperature

Abstract A relatively new, high cis-1,4-polybutadiene and a novel trialkylaluminumnickel-HF catalyst system have been described. This polybutadiene is unique in that it possesses high tack and has exceptionally good processing qualities; the carbon black-loaded and cured rubber possesses good static and dynamic properties. The catalyst system is very effective for producing high molecular weight rubber, suitable for oil extension, and the molecular weight can be controlled by adjusting 1) HF to R3Al ratio, 2) total catalyst concentration and/or 3) polymerization temperature.

Effect of Carbon Black Substitution with Raw and Modified Bentonite on the Thermal Aging Resistance of Natural Rubber Composites

2016 ◽  
Vol 705 ◽  
pp. 8-13 ◽  
Author(s):  
Clare L. Garing ◽  
Bryan B. Pajarito
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Thermal Aging ◽  
Clay Platelet ◽  
Aging Resistance ◽  
Contour Plots ◽  
Activated Bentonite ◽  
Simplex Lattice ◽  
Simplex Lattice Mixture Design

The effect of carbon black (CB) substitution with raw (BNT) and modified (M-BNT) bentonite on the thermal aging resistance of natural rubber (NR) composites was investigated in this study. NR composites were prepared at varied proportions of CB, M-BNT, and BNT using a three-component, third degree simplex lattice mixture design of experiment (DOE). M-BNT was produced by modifying sodium-activated bentonite with tetradecyldimethylamine (TDA) salt and cocamide diethanolamine (CDEA). Thermal aging was performed at 70 and 100°C for 168 and 336 h. Substitution of CB with 5 phr M-BNT gave the highest values of tensile properties (modulus and strength) for both unaged and aged samples. This is attributed to the synergistic effect of CB and M-BNT fillers on the tensile properties of NR composites. In terms of property retention (%), composites filled with M-BNT and BNT clay fillers attained the highest values which signified their excellent thermal aging resistance. This observation proves the barrier effect of clay platelet structure which hinders oxygen diffusion in the rubber. Reduced hierarchical models as function of CB, M-BNT, and BNT proportions were used to generate contour plots for tensile properties of NR composites after 168 h of aging at 70 and 100°C.

STUDIES OF POLYMERS AND OF POLYMERIZATION.: VI. THE VULCANIZATION OF METHYL RUBBER

1932 ◽  
Vol 6 (4) ◽  
pp. 398-408 ◽  
Author(s):  
George Stafford Whitby ◽  
Morris Katz
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Temperature Increase ◽  
Room Temperature ◽  
Breaking Strength ◽  
Synthetic Rubber ◽  
Room Temperature Increase

Samples of synthetic rubber prepared by the polymerization of dimethylbutadiene at room temperature and at 45 °C. respectively were subjected to vulcanization tests in comparison with natural rubber. In an accelerated gum stock containing 3% sulphur the cold polymer gave at best vulcanized products less than one-third as strong and only about one-third as extensible as natural rubber; the heat polymer gave products as extensible but only one-tenth as strong as natural rubber. The incorporation of carbon black greatly increased the strength of the synthetic rubbers, rendering both about half as strong as natural rubber in a similar stock. The vulcanized synthetic rubbers were less "snappy" than natural rubber at room temperature. Increase of temperature improved their speed of retraction, but seriously reduced their breaking strength. Products from the cold polymer showed a greatly increased stiffness and strength at 5 °C. as compared with room temperature, and at about 1 °C. were non-retractible. In general the synthetic rubbers were much more sensitive than natural rubber to change of temperature. A 50:50 mixture of the heat and cold polymers was also subjected to tests.

The Dispersion of Carbon Black in Rubber Part IV. The Kinetics of Carbon Black Dispersion in Various Polymers

1994 ◽  
Vol 67 (2) ◽  
pp. 237-251 ◽  
Author(s):  
A. Y. Coran ◽  
F. Ignatz-Hoover ◽  
P. C. Smakula
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Natural Rubber ◽  
Kinetic Parameters ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Rapid Technique ◽  
Rubber Part ◽  
Kinetics Of ◽  
Carbon Black Dispersion

Abstract A rapid technique for evaluating the rate and state of dispersion of carbon black in natural rubber has been extended to study the dispersion of carbon black in various polymers. The technique measures the extent and rate of dispersion of the black in the rubber. The kinetics of dispersion was characterized for a variety of polymers (e.g. SBR, EPDM, IR, IIR, BR and NR). Kinetic parameters were correlated with molecular weight and molecular weight distribution.

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