The Caoutchol Component of Natural Rubber. A Correction

1942 ◽  
Vol 15 (4) ◽  
pp. 843-846 ◽  
Author(s):  
K. C. Roberts
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Minor Component ◽  
The Other ◽  
Research Association ◽  
Low Viscosity ◽  
Naturally Occurring ◽  
Elastic Substance

Abstract The author recently described a method, developed in Malaya, for separating natural rubber into two main fractions, one containing, among other things, a hydrocarbon which was called caoutchene; the other including an oxygenated substance which constitutes about 2–5 per cent of natural rubber. The latter, which was named caoutchol, was described as a nontacky, freely soluble, highly elastic substance, for which the formula C80H130(OH)2 was suggested. Caoutchene, constituting 87–91 per cent of total rubber, and isolated only in a crude state, was described as tacky, of low tensile strength, and giving solutions of notably low viscosity, and its elongation under tension was stated not to exceed 200 per cent. It was further suggested that the elasticity of rubber was derived essentially from its minor component, caoutchol. The author has now been able to examine again the substance, in collaboration with his colleagues on the staff of the British Rubber Producers' Research Association. Fresh facts have been brought to light, both here and elsewhere, in consequence of which it has been found necessary to amend or withdraw the suggestions originally put forward. Nevertheless it is emphasized that caoutchol is a naturally occurring substance of real interest, quite distinct from artificially oxidized rubbers.

scholarly journals Reinforcement of natural rubber and epoxidized natural rubbers with fillers

2019 ◽  
Vol 1 (1) ◽  
pp. 12-21 ◽  
Author(s):  
Indra Surya ◽  
Nabil Hayeemasae
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Surface Chemistry ◽  
Natural Rubber ◽  
The Other ◽  
Reinforcement Effect ◽  
Cure Time ◽  
Filler Dispersion ◽  
The Difference ◽  
Lower Tensile Strength

The reinforcement of natural rubber (NR) and epoxidized natural rubbers (ENRs) with silica or carbon black (CB) by using a semi-efficient sulfur accelerated vulcanization system has been carried out. It was found that silica caused a longer in cure time compared to CB and due to the dissimilarity of their surface chemistry, it was also found that silica and CB caused the difference in reinforcement effect to those rubbers. Silica caused in filled-vulcanizates of those rubbers with a higher modulus and lower tensile strength compared to their unfilled ones. On the other hand, CB caused enhancements in both modulus and tensile to those rubbers. The investigation on reinforcing efficiencies of those fillers on the rubbers found that the higher reinforcing efficiency of CB was attributed to its better degree of filler dispersion when compared to silica.

The Load Dependence of Side Force and Self-Aligning Torque of Pneumatic Tires

1970 ◽  
Vol 43 (5) ◽  
pp. 995-1004
Author(s):  
A. Schallamach
Keyword(s):  
Experimental Data ◽  
Natural Rubber ◽  
The Other ◽  
Research Association ◽  
Side Force ◽  
Load Dependence ◽  
Other Hand ◽  
Force Curves ◽  
Theoretical Side ◽  
Pneumatic Tires

Abstract A conclusion to be drawn from this analysis of the load dependence of side force and self-aligning torque of pneumatic tires is that agreement between experimental and theoretical side force curves does not necessarily prove the soundness of the theory. On the other hand, even an inadequate theory is successful in suggesting a predictable and useful interrelation between load and slip dependence of the side force. Figure 4 demonstrates that quite a primitive transform of experimental data can lead to a unified presentation of its load and slip dependence although the resulting curve deviates quantitatively from theory in this particular case. This work forms part of a program of research undertaken by the Natural Rubber Producers' Research Association.

Measurement of Tensile Strength of Natural Rubber Vulcanizates at Elevated Temperature

1982 ◽  
Vol 55 (1) ◽  
pp. 66-75 ◽  
Author(s):  
C. L. M. Bell ◽  
D. Stinson ◽  
A. G. Thomas
Keyword(s):  
Tensile Strength ◽  
Elevated Temperature ◽  
Critical Temperature ◽  
Natural Rubber ◽  
Test Piece ◽  
Flaw Size ◽  
High Tensile Strength ◽  
Test Pieces ◽  
Naturally Occurring ◽  
Natural Rubber Vulcanizates

Abstract The tensile strength of test pieces made from natural rubber vulcanizates drops abruptly at a critical temperature which can vary from 40 to 130°C. This variation in critical temperature is shown here to be a result of the variation in critical cut length with temperature. When the naturally occurring flaws in the test piece are smaller than the critical cut length, high tensile strength values occur, but when the flaws are longer than the critical cut length, low tensile strength values occur. The critical cut length decreases as the temperature increases, and the abrupt drop in tensile strength occurs as the critical cut length reaches the natural flaw size in the test piece. The natural flaw size in tensile test pieces depends on the sharpness of the cutter, and for tensile strength measurements at elevated temperature, it is shown that even a slightly blunt cutter may give markedly different results from a sharp one.

Failure Properties of Natural Rubber Double Networks

1995 ◽  
Vol 68 (1) ◽  
pp. 124-131 ◽  
Author(s):  
P. G. Santangelo ◽  
C. M. Roland
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Crosslink Density ◽  
The Other ◽  
Direction Transverse ◽  
Mechanical Fatigue ◽  
Other Hand ◽  
Failure Properties ◽  
The Difference ◽  
Double Networks

Abstract When measured parallel to the curing deformation, double networks of natural rubber have a higher modulus than single networks of equal crosslink density. The difference is greater at higher strains. Despite the higher modulus, the mechanical fatigue lifetimes of double networks were found to be as much as a factor of ten higher than for conventionally crosslinked NR. The double network's tensile strength, on the other hand, was slightly lower. In contrast to these results, the modulus and tensile strength in the direction transverse to the curing strain are minimally affected by the presence of a composite network.

The Chemistry of Natural Rubber

1939 ◽  
Vol 12 (4) ◽  
pp. 760-761
Author(s):  
J. W. Haefele ◽  
E. M. McColm
Keyword(s):  
Tensile Strength ◽  
Carbon Tetrachloride ◽  
Natural Rubber ◽  
Steam Distillation ◽  
Insufficient Attention ◽  
Low Viscosity ◽  
Supernatant Liquid ◽  
Dissolved Air

Abstract Roberts (J. Chem. Soc., 1938, 215, 219) dissolved air-dried films from fresh latex in acetone-carbon tetrachloride and coagulated the solution by the addition of further acetone; the supernatant liquid contained an ingredient which was soluble in ligroin, contained sulfur, might be elastic, and was termed by Roberts, caoutchol. Roberts stated that removal of this caoutchol ingredient caused marked changes in the properties of the remaining rubber, “characterised by its lack of tensile strength and the remarkably low viscosity of its solutions.” This rubber was dried in air for 24 hours, dissolved in benzene, centrifuged, and emulsified with water and the benzene removed by steam distillation. The rubber remaining was tacky and feebly elastic after drying in a vacuum, and was termed caoutchene. Roberts developed the theory that the elasticity of crude rubber is due to the presence of caoutchol and that, without caoutchol, rubber has very poor elasticity and low viscosity in solution. Insufficient attention has been paid to the role of oxygen in the purifications described. Roberts states: “The process has been carefully examined, particularly with respect to the possibility of oxidative or other changes in the constituents. No evidence of such changes has been obtained.” Yet the coagulated rubber, after removal of the caoutchol but prior to steam distillation, was milled in air, and dried in air for 24 hours, during which time considerable oxidation could have occurred.

SILICA-RICH FILLER FOR THE REINFORCEMENT IN NATURAL RUBBER

2012 ◽  
Vol 85 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Kanoktip Boonkerd ◽  
Saowaroj Chuayjuljit ◽  
Dalip Abdulraman ◽  
Weerakul Jaranrangsup
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Tensile Strength ◽  
Particle Size Distribution ◽  
Natural Rubber ◽  
The Other ◽  
Particle Sizes ◽  
Reinforcing Efficacy ◽  
Cure Time ◽  
Jet Milling

Abstract The aim of the study was to determine the reinforcing efficacy of a silica-rich filler, pottery stone (PS), in natural rubber (NR). The effects of amount and particle size of PS on curing and mechanical properties of the NR compounds were determined. The PS was first divided into four groups. Two of these were raw PS without grinding, which were sieved to particle sizes of less than 106 μm (PS(<106)) and less than 38 μm (PS(<38)). The other two were ground PS, one by current jet milling to obtain PS(JM), and the other by wet ball milling to obtain PS(BM). The particle size distribution of the four different PS prior to ultrasonication was in the ranked order (largest to smallest size), based upon their d(0.5) and d(0.9), of PS(BM), PS(<106), PS(<38), and PS(JM). However, after ultrasonication for 10 min, PS(BM) had the smallest d(0.5) at less than a micron, while the remaining three PS groups showed nearly the same d(0.5) being within the range of 3–5 μm. The presence of PS shortened the cure time, with PS(BM) inducing the greatest decrease in the cure time, while this was somewhat dose independent for at least PS(JM) and PS(<106). For all four PS groups, when present at 20 phr or more, the delta torque of the PS filled NR was higher than that of the unfilled one. However, the addition of PS had no significant effect on the number of crosslinks. With respect to the mechanical properties of the NR filled with PS, it was generally observed that NR filled with PS(BM) at 20–50 phr gave a higher tear and tensile strength, abrasion resistance, and hardness than both the unfilled NR and also the NR filled with the other three PS groups. The optimum PS(BM) loading was at 30 phr.

Thermoplastic Elastomer Based on Epoxidized Natural Rubber/Polyamide-12 and Co-Polyamide-12 Blends

2012 ◽  
Vol 626 ◽  
pp. 58-61 ◽  
Author(s):  
Rawviyanee Romin ◽  
Charoen Nakason ◽  
Anoma Thitithammawong
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Thermoplastic Elastomer ◽  
Thermoplastic Elastomers ◽  
The Other ◽  
Epoxidized Natural Rubber ◽  
Dynamic Vulcanization ◽  
Elongation At Break ◽  
Polyamide 12

Thermoplastic elastomers based on blending of epoxidized natural rubber with 30 mol% epoxide (ENR-30) with polyamide-12 (PA-12) (i.e., ENR-30/PA-12) and blending of ENR-30 with co-polyamide-12 (ENR-30/CO-PA-12) were prepared by dynamic vulcanization technique. It was found that the dynamically cured ENR-30/PA-12 blends exhibited higher tensile strength, Youngs modulus and hardness than those of the ENR-30/CO-PA-12 blends. However, the elongation at break of the ENR-30/PA-12 blend was very poor and hence the tension set could not be determined. On the other hand, the ENR-30 contents in the dynamically cured ENR-30/CO-PA-12 influence on various properties. These include lowering of stiffness and tensile properties together with enhancing elastic properties (i.e. lower tension set and tan ) of the blends.

Tensile Strength of Protein-free Natural Rubber and its Vulcanizate Soaked in Water

2020 ◽  
Vol 93 (9) ◽  
pp. 293-299
Author(s):  
Luu Thanh HUYEN ◽  
Chen Ao RAN ◽  
Yoshimasa YAMAMOTO ◽  
Seiichi KAWAHARA
Keyword(s):  
Tensile Strength ◽  
Natural Rubber

Pengaruh penambahan natural rubber (NR), epoxidation natural rubber (ENR-46) dan chlorprene rubber (CR) pada sifat kompon termoplastik

2020 ◽  
Vol 26 (2) ◽  
pp. 62-69
Author(s):  
Farida Ali ◽  
Tuti I. Sari ◽  
Andi A. Siahaan ◽  
Al-Kautsar D. Arya ◽  
Tri Susanto
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Vinyl Chloride ◽  
Butadiene Rubber ◽  
Elongation At Break ◽  
Nitrile Butadiene Rubber ◽  
Poly Vinyl Chloride

Penelitian ini untuk mengetahui pengaruh penambahan Natural Rubber (NR) dan Epoxidation Natural Rubber (ENR-46) dengan kompatibiliser Chlorprene Rubber (CR) pada aplikasi kompon termoplastik Poly Vinyl Chloride (PVC) dan Nitrile Butadiene Rubber (NBR), variabel penelitian meliputi ENR-46/PVC/NBR/CR, NR/PVC/NBR/CR dan CR-NR/PVC/NBR, CR-ENR-46/PVC/NBR. Parameter pengujian sifat fisik-mekanik : Hardness (Shore A), Tensile Strength (Mpa), Elongation at Break (%) dan ketahanan terhadap pelarut minyak (n-Pentane, Toluene, Hexane dan Pertalite). Hasil penelitian didapatkan untuk sifat fisik-mekanik, semakin banyak penambahan NR Kekerasan kompon termoplastik akan menurun, Tensile Strength dan Elongation at Break kompon akan meningkat begitu juga dengan CR-NR. Tetapi berbanding terbalik hasilnya untuk ENR-46 dan CR-ENR-46. Pengujian Ketahanan terhadap pelarut minyak semakin banyak penambahan ENR-46 Ketahanan kompon termoplastik terhadap pelarut akan meningkat, hasil yang sama juga pada CR-ENR-46. Tetapi berbanding terbalik hasilnya dengan penambahan NR dan CR-NR pada kompon termoplastik.

EFFECT OF ZINC DITHIOCARBAMATES AND THIAZOLE-BASED ACCELERATORS ON THE VULCANIZATION OF NATURAL RUBBER

2012 ◽  
Vol 85 (1) ◽  
pp. 120-131 ◽  
Author(s):  
Md. Najib Alam ◽  
Swapan Kumar Mandal ◽  
Subhas Chandra Debnath
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Reaction Mechanism ◽  
Natural Rubber ◽  
High Performance ◽  
Binary Systems ◽  
Synergistic Activity ◽  
Tetramethylthiuram Disulfide

Abstract Several zinc dithiocarbamates (ZDCs) as accelerator derived from safe amine has been exclusively studied in the presence of thiazole-based accelerators to introduce safe dithiocarbamate in the vulcanization of natural rubber. Comparison has been made between conventional unsafe zinc dimethyldithiocarbamate (ZDMC) with safe novel ZDC combined with thizole-based accelerators in the light of mechanical properties. The study reveals that thiuram disulfide and 2-mercaptobenzothiazole (MBT) are always formed from the reaction either between ZDC and dibenzothiazyledisulfide (MBTS) or between ZDC and N-cyclohexyl-2-benzothiazole sulfenamide (CBS). It has been conclusively proved that MBT generated from MBTS or CBS reacts with ZDC and produces tetramethylthiuram disulfide. The observed synergistic activity has been discussed based on the cure and physical data and explained through the results based on high-performance liquid chromatography and a reaction mechanism. Synergistic activity is observed in all binary systems studied. The highest tensile strength is observed in the zinc (N-benzyl piperazino) dithiocarbamate-accelerated system at 3:6 mM ratios. In respect of tensile strength and modulus value, unsafe ZDMC can be successfully replaced by safe ZDCs in combination with thiazole group containing accelerator.

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