The Effect of Softeners in Rubber

1953 ◽  
Vol 26 (1) ◽  
pp. 152-155
Author(s):  
Ira Williams
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
High Modulus ◽  
Mineral Oils ◽  
Cohesive Forces ◽  
Commercial Use ◽  
Effect Of Solvents ◽  
Vulcanized Rubber ◽  
Unfavorable Effect ◽  
The Cost

Abstract The use of oils and liquid softeners to assist in the mastication and processing of rubber or to produce softer vulcanized stocks has been standard practice since the early commercial use of rubber. More recently certain synthetic rubbers, polymerized under special conditions, have been treated with rather large amounts of mineral oils, with a resulting decrease in the cost of the rubber and apparently with no unfavorable effect on the rubber in most instances. A number of investigators have reported the effect of swelling agents on the properties of vulcanized rubber. Busse discusses the effect of solvents in a general way. Tiltman and Porritt conclude that the decrease in modulus caused by swelling in benzene is caused by a “loosening of cohesive forces.” Tire treads of natural rubber containing such softeners as pine tar and mineral rubber decrease in wear resistance in proportion to the softener content. Well vulcanized rubber of high modulus is most resistant to swelling in oils. Naunton, Jones, and Smith find that unaccelerated stocks lose the most tensile strength after being swollen, that milling of the raw rubber increases swelling, and that the presence of softeners in the rubber during vulcanization reduces the oil resistance. A limited amount of swelling has been reported to have little effect on the tensile strength of vulcanized natural rubber. Bourbon points out that separating the rubber molecules with solvent decreases the rate of vulcanization.

The Effect of Solvents on the Stress-Strain Curve of Vulcanized Rubber

1930 ◽  
Vol 3 (1) ◽  
pp. 19-21 ◽  
Author(s):  
H. A. Tiltman ◽  
B. D. Porritt
Keyword(s):  
Tensile Strength ◽  
Marked Effect ◽  
Strain Curve ◽  
Theoretical Interest ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Cohesive Forces ◽  
Effect Of Solvents ◽  
Vulcanized Rubber ◽  
Permanent Effect

Abstract (1) The results indicate that the rigidity of a piece of vulcanized rubber is considerably reduced by the absorption of small amounts of a solvent; thus, at a strain of 6 ( = 600 per cent elongation) the absorption of 5 per cent by weight ( = 8 per cent by volume) of benzene lowers the rigidity by 21 per cent. (2) The greatest effect is produced by the first 20 or 30 per cent (by weight) of absorbed benzene, further absorption having a less marked effect on the stress-strain curve. (3) The absorption of solvent seems to have very little effect on the breaking elongation, although the tensile strength is considerably lowered. This conclusion, however, is probably no longer true in the case of rubber swollen by immersion in liquid, where the absorption is very much greater than in the present tests. (4) Absorption of solvent followed by complete drying appears to produce a slight, but technically negligible, permanent effect on the stress-strain curve. It is evident from these results that when it is necessary to use solvents, either in the process of manufacture or the after-treatment of rubber products, these should be selected as free as possible from high-boiling constituents liable to be permanently retained by the rubber with consequent detriment to its strength. A conclusion of some theoretical interest is that since all the stresses in the present investigation were calculated on the dimensions of the original dry rubber, the low rigidity of swollen rubber cannot be ascribed simply to the “dilution” of the rubber by the absorbed liquid, but must be due to a loosening of the cohesive forces between the ultimate particles of the material.

Mechanochemical Devulcanization of Vulcanized Gum Natural Rubber

2005 ◽  
Vol 21 (3) ◽  
pp. 183-199
Author(s):  
G.K. Jana ◽  
C.K. Das
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Three Dimensional ◽  
Elongation At Break ◽  
Tear Strength ◽  
Vulcanized Rubber ◽  
Dimensional Network ◽  
Polymeric Chains ◽  
Cure Time

De-vulcanization of vulcanized elastomers represents a great challenge because of their three-dimensional network structure. Sulfur-cured gum natural rubbers containing three different sulfur/accelerator ratios were de-vulcanized by thio-acids. The process was carried out at 90 °C for 10 minutes in an open two-roll cracker-cum-mixing mill. Two concentrations of de-vulcanizing agent were tried in order to study the cleavage of the sulfidic bonds. The mechanical properties of the re-vulcanized rubber (like tensile strength, modulus, tear strength and elongation at break) were improved with increasing concentrations of de-vulcanizing agent, because the crosslink density increased. A decrease in scorch time and in optimum cure time and an increase in the state of cure were observed when vulcanized rubber was treated with high amounts of de-vulcanizing agent. The temperature of onset of degradation was also increased with increasing concentration of thio-acid. DMA analysis revealed that the storage modulus increased on re-vulcanization. From IR spectroscopy it was observed that oxidation of the main polymeric chains did not occur at the time of high temperature milling. Over 80% retention of the original mechanical properties (like tensile strength, modulus, tear strength and elongation at break) of the vulcanized natural rubber was achieved by this mechanochemical process.

The Effect of Thermal Aging on Mechanical Properties and Morphological Properties of Thermoplastic Vulcanizates Based on Natural Rubber and Polystyrene

2020 ◽  
Vol 990 ◽  
pp. 262-266
Author(s):  
Prathumrat Nu-Yang ◽  
Atiwat Wiriya-Amornchai ◽  
Jaehoon Yoon ◽  
Chainat Saechau ◽  
Poom Rattanamusik
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Natural Rubber ◽  
Thermal Aging ◽  
Morphological Properties ◽  
Vulcanized Rubber ◽  
Thermoplastic Vulcanizates ◽  
Internal Mixer ◽  
Processing Properties

Thermoplastic vulcanizates or TPVs is a type of materials exhibiting excellent properties between thermoplastic and elastomer by combining the characteristics of vulcanized rubber with the processing properties of thermoplastics. This research aims to study the effect of thermal aging on the morphology and mechanical properties of thermoplastic vulcanizates (TPVs) based on a mixture of natural rubber (NR) and polystyrene (PS). TPVs samples were prepared using the internal mixer at a mass ratio of NR/PS 70/30, 50/50, 30/70 and 0/100. Tensile properties and impact strength showed that when the amount of NR increased tends of impact strength and elongation at break increased but tends of tensile strength decreased. On the other hand, tends of tensile strength for thermal aging at 70°C for 3 days increased when the amount of PS increase. The blending ratio of NR / PS at 70/30 is the best. It gave a worthy increase from 19.94 MPa to be 25.56 MPa (28.18%).

High Quality Foams from NIR Latex

1966 ◽  
Vol 39 (3) ◽  
pp. 755-762
Author(s):  
S. N. Angove ◽  
E. S. Graham ◽  
G. Hilditch ◽  
R. A. Stewart ◽  
F. L. White
Keyword(s):  
Tensile Strength ◽  
Low Temperature ◽  
Natural Rubber ◽  
Compression Modulus ◽  
High Modulus ◽  
High Tensile Strength ◽  
High Quality ◽  
Foam Rubber ◽  
Oil Resistance ◽  
Low Temperature Flexibility

Abstract Foam rubber properties have been measured for NIR latexes as a function of acrylonitrile content of the copolymer and as a function of ratio of NIR latex to NR latex and high modulus SBR latex. Foam rubber made from NIR latex had good aging and oil resistance, combined with the desirable high tensile strength and elongation characteristic of natural rubber foam. Resilience and low temperature flexibility of NIR foams were found to be lower than that achieved with foams of either SBR or NR latexes. Although compression modulus of NIR foam was lower than that of a high modulus SBR foam and approximately equivalent to that of NR foam, it was effectively increased by the addition of either such SBR latex or a high-styrene resin latex.

scholarly journals Preparation and modification of natural rubber blends for water purification treatment usage

2020 ◽  
Author(s):  
Wenfa Dong ◽  
Ruogu Tang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Relative Volume ◽  
Curing Time ◽  
Water Industry ◽  
High Modulus ◽  
Elongation At Break ◽  
Tear Strength ◽  
Rubber Blends

<div>The water industry used NR was selected for blending with SBR. A series of NR/SBR vulcanizates were prepared through three different vulcanization systems, conventional vulcanization (CV), effective vulcanization (EV) and semi-effective vulcanization (SEV) respectively, basing on each formulation and optimum curing time. We examined the mechanical properties of NR/SBR vulcanizates including tensile strength, tear strength, elongation at break, modulus, Shore A hardnessand and relative volume abrasion. The results indicated that NR/SBR vulcanizates prepared in different systems differed in mechanical properties. Vulcanizates prepared via CV showed higher tensile and tear strength; vulcanizates prepared via EV had high modulus and hardness, and vulcanizates prepared via SEV performed high abrasion resistance. </div>

X-Ray Study of the Crystallization of Vulcanized Rubber during Stretching. II.

1951 ◽  
Vol 24 (3) ◽  
pp. 541-549 ◽  
Author(s):  
V. I. Kasotochkin ◽  
B. V. Lukin
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Crystal Formation ◽  
Oxidative Destruction ◽  
Ray Method ◽  
X Ray ◽  
Vulcanized Rubber ◽  
Crystal Content

Abstract 1. The relation between the crystal content of stretched vulcanizates to the time of vulcanization for different mixtures of natural rubber was studied by the x-ray method. 2. It was shown that the tensile strength is a function of the crystal content of the stretched vulcanizate and of the total time of vulcanization. 3. The nature of crystal formation depends on the following factors: changes of density of the network of sulfur bridges, their distribution, the degree of oxidative destruction, and the quantity of bound sulfur which has not formed bridges between the molecular chains.

Polybutadienes of Controlled Cis, Trans and Vinyl Structures

1959 ◽  
Vol 32 (2) ◽  
pp. 614-627 ◽  
Author(s):  
J. N. Short ◽  
G. Kraus ◽  
R. P. Zelinski ◽  
F. E. Naylor
Keyword(s):  
Tensile Strength ◽  
Low Temperature ◽  
Natural Rubber ◽  
Physical Properties ◽  
Abrasion Resistance ◽  
High Hardness ◽  
High Modulus ◽  
High Tensile Strength ◽  
Truck Tires ◽  
Wide Range

Abstract The physical properties of polybutadiene vulcanizates have been measured as a function of polymer microstructure. Although the over-all properties of any one polybutadiene are determined by the relative ratio of cis, trans and vinyl units in the polymer chain, marked changes in physical properties do not occur until a relatively pure configuration is approached or unless the raw polymer displays crystallinity. Thus, polybutadienes containing more than 85 per cent cis, trans or vinyl units are characteristically different from each other and the differences are accentuated as the isomeric forms approach 100 per cent of a given configuration. Polybutadiene of 95 per cent cis configuration displays very low heat generation and high resilience (equaling natural rubber in these properties) and excellent abrasion resistance. trans-Polybutadiene (90 per cent), a crystalline plastic in the raw state, becomes rubbery after vulcanization. Gum vulcanizates possess high tensile strength, and tread stocks display high modulus and tensile strength, high hardness and fair hysteresis properties. Vulcanizates of amorphous 94 per cent vinyl polybutadiene are characterized by fair tensile properties, low hysteresis, and poor low temperature properties. Crystalline syndiotactic polybutadiene, 70 per cent vinly, displays much higher gum and tread tensile strengths than its amorphous counterpart. Amorphous polybutadienes containing less than 70–80 per cent of any one configuration are generally similar in most properties, and resemble emulsion polybutadiene in many respects. The wide range of properties of the various polybutadienes makes them suitable for many applications. cis-Polybutadiene is an excellent tire rubber, which has given as much as 40 per cent greater abrasion resistance than natural rubber in passenger tire tests. Heavy duty 10:00 × 20 truck tires fabricated with a 1:1 blend of cis-polybutadiene and natural rubber in the treads have given slightly better abrasion ratings and lower running temperatures than control tires fabricated entirely from natural rubber. Amorphous 80 per cent cis-polybutadiene has been found to possess exceptionally good low temperature properties, far superior to present arctic-type unsaturated elastomers, trans-Polybutadienes by virtue of their high modulus, high tensile strength, and high hardness could be utilized in the preparation of hard rubber goods, floor tiles, and shoe soles. While none of these polybutadienes is yet available commercially, their unusual properties and potential applicability in many areas should lead to their manufacture in the future.

Thermoplastic Natural Rubber Based on Blending of Co-Polyester: Effect of Amount of Epoxide Groups in Epoxidized Natural Rubber on Preperties

2012 ◽  
Vol 626 ◽  
pp. 50-53 ◽  
Author(s):  
Krisna Sasdipan ◽  
Azizon Kaesaman ◽  
Charoen Nakason
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Storage Modulus ◽  
Complex Viscosity ◽  
Epoxidized Natural Rubber ◽  
Dynamic Vulcanization ◽  
Elongation At Break ◽  
Vulcanized Rubber ◽  
Thermoplastic Matrix ◽  
Thermoplastic Natural Rubber

TPNRs based on blending of co-polyester (i.e., PBT/PC) and epoxidized natural rubber (ENR) with various epoxide content (i.e., 10, 20, 30, 40 and 50 mol% epoxide) were prepared by dynamic vulcanization. It was found that the co-polyester/ENR blends gave better properties (i.e., mechanical, dynamic mechanical, morphological and oil resistant properties) than that of co-polyester/unmodified NR blend. It was also found that co-polyester/ENR with 50 mol% epoxide exhibited the highest tensile strength, elongation at break, modulus at 100% elongation, hardness, storage modulus, complex viscosity and oil resistant properties but showed the lowest tension set value. This indicates the highest elasticity. Moreover, it was found that size of vulcanized rubber domains dispersed in thermoplastic matrix decreased with increasing the epoxide content in ENR molecules.

Study on Natural Rubber Quality of Micro-Cut Tapping with Gas-Stimulation

2013 ◽  
Vol 834-836 ◽  
pp. 175-179
Author(s):  
Kai Dian Wang ◽  
Mao Fang Huang ◽  
Chun Liang Yang ◽  
Zong Qiang Zeng ◽  
Zhi Xiong Liang ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Natural Rubber ◽  
Protein Content ◽  
Dynamic Property ◽  
Control Group ◽  
Vulcanized Rubber ◽  
The Difference

The natural rubber samples produced by conventional tapping methods were used as a control, then analyzed the dry rubber property of natural rubber, the dynamic property and Physical & mechanical property of vulcanized rubber using Rubber processing analyzer and Thermogravimetric Analyze the difference between the properties of dry rubber and vulcanized rubber produced by Micro-cut Tapping with Gas-stimulation. The results indicated that the tensile strength, tear strength elastic modulus of dry rubber that produced by Micro-cut Tapping with Gas-stimulation are respectively 20%, 7% lower than the control. The protein content of dry rubber materials produced by Micro-cut Tapping with Gas-stimulation is 16.7% higher than control group.

Dependence of Tensile Strength of Vulcanized Rubber on the Degree of Cross-Linking

1950 ◽  
Vol 23 (1) ◽  
pp. 27-43
Author(s):  
Paul J. Flory ◽  
Norman Rabjohn ◽  
Marcia C. Shaffer
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Chain Scission ◽  
General Character ◽  
Cross Linking ◽  
Vulcanized Rubber ◽  
Relationship Of ◽  
The Relationship ◽  
Considerable Detail ◽  
Proportionality Relationship

Abstract The suitability of disazodicarboxylates as quantitative cross-linking agents for the preparation of rubber vulcanizates of known degrees of cross-linking has been emphasized previously. In a recent paper we have presented the results of an investigation on the dependence of the equilibrium force of retraction on the elongation and degree of cross-linking of rubber and GR-S vulcanized with these compounds. The present paper reports an extension of these investigations of the relationship of physical properties of rubberlike materials to their network structure. Specifically, the tensile strength of azo vulcanized natural rubber has been explored as a function of the degree of cross-linking and of the extent of modification of the chain units. The tensile strengths of natural rubber specimens vulcanized to various extents using sulfur alone or sulfur in conjunction with various accelerators have been investigated in considerable detail recently by Gee, who has emphasized the critical dependence of the tensile strength on the degree of cross-linking. Values for the latter quantity, however, were deduced indirectly from the equilibrium force of retraction using the simple proportionality relationship between force of retraction and degree of cross-linking afforded by the theory of rubber elasticity. This relationship is known to be only approximately valid. Furthermore, the effects on the force of retraction of chain scission, which doubtless accompanied some of the vulcanizations to a considerable degree, were disregarded. For these reasons, Gee's values for the degrees of cross-linking occurring in his vulcanizates are only approximate estimates, and in a few cases they may be seriously in error. Nevertheless, the general character of the relationship between tensile strength and degree of cross-linking which he obtained is confirmed by our results on rubber samples quantitatively cross-linked with measured proportions of decamethylene-dismethyl azodicarboxylate.

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