Crystallization and Tensile Strength of Vulcanized Natural Rubber Compounds

1953 ◽  
Vol 26 (1) ◽  
pp. 17-24 ◽  
Author(s):  
S. H. Morrell ◽  
Jan Stern
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Cross Linking ◽  
Rubber Compounds

Abstract The effect which changes in the degree of cross-linking have on the crystallization of stretched rubber has been studied by observing the densities of a series of peroxide-cured natural rubber compounds. It was found that at any one elongation, crystallization first increased and then decreased with increase in the degree of cross-linking. The significance of this maximum and the relation between crystallization and tensile strength are discussed.

Tensile Strengths of Pure Gum Natural Rubber Compounds

1948 ◽  
Vol 21 (2) ◽  
pp. 301-313 ◽  
Author(s):  
Geoffrey Gee
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Plastic Flow ◽  
Cross Linking ◽  
Single Factor ◽  
Structural Modifications ◽  
Rubber Compounds

Abstract The tensile properties of a range of pure-gum natural rubbers have been reviewed, and it has been shown that their principal features can be understood on the assumption that the tensile strength measured in a given test depends directly on the amount of crystallization at break. The most important single factor in determining tensile strength is the degree of cross-linking. Cross-linking is only needed in order to prevent plastic flow, thus making it possible for the molecules to align themselves by stretching, and hence to crystallize. A very highly cross-linked rubber is weak because the load required to stretch it is so high that the rubber is broken before the elongation becomes large enough to produce crystallization. In general, vulcanization also involves reactions, e.g., the combination of sulfur with the rubber, which inhibit crystallization by producing structural modifications of the rubber. These reduce the tensile strength, especially when the degree of cross-linking is large. These ideas readily explain the effects of swelling and of the temperature of test. They are also used in a brief discussion of the phenomena of overcure, reversion, and aging.

Characterization of Snap-On Calf Nipple Product and Development of its Compound Formulation Based on Natural Rubber

2017 ◽  
Vol 744 ◽  
pp. 282-287
Author(s):  
Sarawut Prasertsri ◽  
Sansanee Srichan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Calcium Carbonate ◽  
Carbon Black ◽  
Natural Rubber ◽  
Soxhlet Extraction ◽  
Rubber Compound ◽  
Rubber Compounds ◽  
Rubber Component

This research aimed to develop the formulation of natural rubber filled with carbon black, silica and calcium carbonate for rubber calf nipple application. The reverse engineering was performed on the calf nipple product to analyze the rubber type and component by using Soxhlet extraction, thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) techniques. Furthermore, mechanical properties were examined to act as benchmark for the rubber compound design. The results showed that rubber component in the nipple product was natural rubber, whereas two filler types revealed as carbon black and calcium carbonate with 10 and 35 of the total weight. In addition, rubber nipple showed the hardness of 46±1 Shore A and tensile strength of 5.3±0.60 MPa. From the investigation of the properties of developed rubber compounds in this work, it was found that the mechanical properties depended on type and content of filler. The required mechanical properties of vulcanizates were achieved at 20 phr of carbon black (N330), 20 phr of silica and 120 phr of calcium carbonate.

Influences of Particle Sizes on Properties of Natural Rubber/Waste Ground Rubber Powders Blends

2013 ◽  
Vol 773 ◽  
pp. 668-672
Author(s):  
Jun Liang Liu ◽  
Ping Liu ◽  
Xiao Qiang Tang ◽  
Dong Zeng ◽  
Xing Kai Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Chemical Activation ◽  
Cross Linking ◽  
Particle Sizes ◽  
Elongation At Break ◽  
Tear Strength ◽  
Rubber Waste ◽  
Ground Rubber

In this paper, the blends of natural rubber with waste ground rubber powders have been prepared by mechano-chemical activation method. The influences of particle sizes on both processing performances and mechanical properties have been investigated. The results indicated that: the blends with waste ground rubber powders of smaller particle sizes approached to higher surface tensile and easily mechano-chemical activation, which led to the formation of complete homogenous re-vulcanization cross-linking structure and resulted in the improvements of the whole performances of the final products. The tensile strength, the elongation at break and tear strength approached to the highest value of 20.7MPa, 530% and 33.0 kN/m as the 100mesh waste ground rubber powders were used as the starting materials.

Thermoreversible cross-linking of maleated natural rubber with glycerol

2018 ◽  
Vol 51 (5) ◽  
pp. 406-420 ◽  
Author(s):  
Nuttida Srirachya ◽  
Takaomi Kobayashi ◽  
Kumarjyoti Roy ◽  
Kanoktip Boonkerd
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Succinic Anhydride ◽  
Processing Method ◽  
Cross Linking ◽  
Hydroxyl Groups ◽  
Reactive Processing ◽  
Cross Links ◽  
Maleated Natural Rubber

In this article, thermoreversible covalent cross-linking of maleated natural rubber (MNR) with glycerol was studied. Firstly, NR was grafted with maleic anhydride using a reactive processing method. The result showed that MNR was successfully obtained without the addition of initiator. The highest grafting was 1.76%. Secondly, the obtained MNR was dissolved in toluene and then mixed with glycerol, which is used in this study as the thermoreversible cross-linking agent. Fourier transform infrared spectra of the casted MNR film mixed with glycerol showed that upon heating, covalent ester cross-links were formed via the reaction of succinic anhydride ring with hydroxyl groups of glycerol. The swelling test indicated that the swelling index (%) decreased with increasing glycerol loading. This indicated that the degree of cross-linking directly depended on the amount of glycerol. The tensile strength and modulus were significantly improved upon increasing the level of cross-linking. The MNR cross-linked with glycerol can be remolded at 150°C more than three times. After remolding, the mechanical properties decreased with increasing recycling round.

MECHANICAL PROPERTIES AND CURE TEST OF A NATURAL RUBBER/POLY(VINYL ALCOHOL) BLEND

2012 ◽  
Vol 85 (1) ◽  
pp. 147-156 ◽  
Author(s):  
Sa-Ad Riyajan ◽  
Suwit Chaiponban ◽  
Sasitorn Chusri ◽  
Supayang Piyawan Voravuthikunchai
Keyword(s):  
Tensile Strength ◽  
Antibacterial Activity ◽  
Natural Rubber ◽  
Polymer Blend ◽  
Maleic Acid ◽  
Acid Content ◽  
Attenuated Total Reflection ◽  
Curing Temperature ◽  
Cross Linking ◽  
Curing Time

Abstract Properties and antibacterial activity of polymer blend films prepared from polyvinyl alcohol (PVA) and natural rubber (NR) blends, in the presence of maleic acid as a cross-linking agent were studied. The effect of the maleic acid content, curing temperature, and curing time on the properties of the polymer blend was investigated. Cross-linking between PVA and maleic acid was observed by attenuated total reflection mode–Fourier transform infrared spectroscopy at 1152 cm−1. The swelling ratio of the polymer blend decreased as a function of the increase of the maleic acid content. The tensile strength of the polymer blend increased with an increase of both the maleic acid and the curing time. The highest tensile strength of the samples was observed with 40% w/w maleic acid after a 24 h curing time at 120 °C. The elongation at the break of 60/40 NR/PVA was ∼500% at 120 °C for 1 h. In addition, the polymer blend showed good antibacterial activity with Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922, and Acinetobacter baumannii JVC 1053 and could find many applications.

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.

Degradation of Silica-Reinforced Natural Rubber by UV Radiation and Humidity in Soil

2017 ◽  
Vol 751 ◽  
pp. 314-319 ◽  
Author(s):  
Manuchet Reowdecha ◽  
Chalermchat Sukthaworn ◽  
Peerapan Dittanet ◽  
Nantina Moonprasith ◽  
Thipjak Na Lampang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Soil Surface ◽  
Solar Simulator ◽  
Cross Sectional ◽  
Rubber Compounds ◽  
Natural Rubber Composites ◽  
One Step ◽  
Agriculture Products ◽  
Composite Samples

In this research study, the degradation of natural rubber was applied for applications in agriculture products such as rubber mulch. This work included the synthesis of 20% wt silica/ natural rubber composites from high ammonia concentrate latex (HA) and fresh latex (FL). They were casted by film casting. The experimental study of rubber composite degradation was done by putting the samples underground and above the soil surface under accelerated degradation test box equipped with a solar simulator lamp for a period of 50 days. Samples were characterized by scanning electron microscopy (SEM) to examine the dispersion on cross-sectional area between natural rubber and silica. Thermogravimetric analysis (TGA) was used to analyze the thermal stability of the composites. Tensile strength (MPa), modulus at 100% elongation (MPa), and elongation at break (%) of the samples after aging were tested by focusing on. It was found that thermal degradation of natural rubber compounds consisted of one step of mass loss between 341°C and 455°C. The SEM result showed good dispersion of Si in the rubber samples. Moreover, it was found that before aging, the composite samples had higher tensile strength than that of the rubber. After aging, the composite samples had lower tensile strength than that of the rubber. Elongation @ break value of HA/Si and FL/Si after aging were decreased obviously.

Curing Characteristics and Tensile Properties of White Fly Ash Filled Natural Rubber Compounds

2014 ◽  
Vol 625 ◽  
pp. 753-756
Author(s):  
Hisyam Mokhtar ◽  
Razif Nordin ◽  
Saidatulakmar Shamsudin ◽  
N.Z. Noriman
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Cure Characteristics ◽  
Rubber Compounds ◽  
Curing Characteristics ◽  
Cure Time

The effect of white fly ash (WFA) on cure characteristics and tensile properties of natural rubber compounds were investigated in the range of 0 to 30 phr. The size of WFA that is used in this study was 45-75 μm. Based on the result, it is found that the scorch time and cure time decreased with increasing of WFA loading. The tensile strength gradually increased to the maximum at 5 phr WFA. The further increase of WFA loading led to the decrease in tensile strength. Tensile properties such as M100 (stress at 100 % elongation) was gradually increased with the increasing of WFA loading, meanwhile, the elongation break showed a decreasing trend.

Oxidation of GR-S and Other Elastomers

1947 ◽  
Vol 20 (3) ◽  
pp. 747-759
Author(s):  
John O. Cole ◽  
James E. Field
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Physical Properties ◽  
Experimental Methods ◽  
Chain Scission ◽  
Cross Linking ◽  
Antioxidant Action ◽  
Mechanism Of Oxidation ◽  
Natural Rubber Vulcanizates

Abstract The effect of heat aging on the physical properties of an elastomer is generally considered the result of oxidation, which produces both chain scission and cross-linking in the polymer. Early in the development of GR-S, a marked difference in the aging of GR-S and natural rubber vulcanizates was observed. From the effect of aging on hardness, tensile strength, modulus, and elongation it appeared that cross-linking occurred more rapidly than chain scission with GR-S, but the reverse was true with natural rubber. The work reported here was undertaken to provide a better understanding of the differences in aging of GR-S and natural rubber and to introduce new experimental methods for studying the mechanism of oxidation and antioxidant action in elastomers.

Mechanical Properties of Montmorillonite-Filled Natural Rubbers Compatibilized by Epoxidized Natural Rubbers

2012 ◽  
Vol 488-489 ◽  
pp. 93-97
Author(s):  
Pranut Potiyaraj ◽  
Sittiporn Ngamsurat ◽  
Wasan Poklong
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Epoxidized Natural Rubber ◽  
Elongation At Break ◽  
Modified Montmorillonite ◽  
Rubber Compounds ◽  
Filler Dispersion ◽  
Reinforcing Filler ◽  
Organomodified Montmorillonite

The effects of epoxidized natural rubber as a compatibilizer in modified-montmorillonite filled natural rubber were studied. Natural rubber was compounded with 2, 5 and 10 parts per hundred rubber (phr) of organomodified montmorillonite as a reinforcing filler and cured by using a conventional sulfuric system. Epoxidized natural rubber with 25 and 50 mol% epoxidic units (ENR25 and ENR50, respectively) was used as compatibilizer at the amount of 5, 10 and 15 phr. Rubber compounds were then tested for their curing properties. Test specimens for mechanical testing were prepared by compression molding. The use of montmorillonite as a filler in natural rubber efficiently improved mechanical properties that are tensile strength, modulus, elongation at break, tear strength and hardness, especially with the small amount of montmorillonite. This is supposed to be related to intercalation and exfoliation process. The increasing amount of montmorillonite caused the filler to be agglomerated thus the reinforcing efficiency was reduced and some mechanical properties were dropped. It was further founded that epoxidized natural rubber compatibilized montmorillonite filled natural rubber effectively. As the amount of epoxidized natural rubber increased, the mechanical properties tended to increase. The presence of epoxidized natural rubber improved filler-rubber interaction and filler dispersion. The compatibilizing efficiency of ENR25 was slightly superior to that of ENR50. This is because ENR 25 contains more double bonds than ENR 50 hence higher strain-induced crystallinity is occurred

Sign in / Sign up

Export Citation Format

Share Document