Mechanochemical Devulcanization of Vulcanized Gum Natural Rubber

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.

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Effect of Ashes as Biomass in Silica Filled Natural Rubber

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.735.153 ◽

2017 ◽

Vol 735 ◽

pp. 153-157

Author(s):

Wasinee Pinpat ◽

Wirunya Keawwattana ◽

Siree Tangbunsuk

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Natural Rubber ◽

Rice Husk Ash ◽

Silica Content ◽

Elongation At Break ◽

Compression Set ◽

Cure Time ◽

Oil Palm Ash ◽

Reinforcing Filler

Silica has been used as reinforcing filler in natural rubber for a period of time as it results in excellent properties for NR vulcanizes. Rice husk ash (RHA), bagasse ash (BA), and oil palm ash (OPA) obtained from agricultural wastes are mainly composed of silica in the percentage of 80.00%, 57.33%, and 40.20% by weight, respectively. The effect of these fillers on cure characteristics and mechanical properties of natural rubber materials at fixed silica content at 35 parts per hundred of rubber (phr) were investigated. The results indicated that ashes showed greater cure time compared to that of the silica. The incorporation of ashes into natural rubber gradually improved compression set but significantly decreased tensile strength, elongation at break, and resilience. Moreover, young's modulus increased, while hardness showed no significant change with the addition of ashes. Overall results indicated that ashes could be used as cheaper fillers for natural rubber materials where improved mechanical properties were not critical.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.773.668 ◽

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.

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Preparation and Properties of Sponge Rubber Based on Natural Rubber and Cassava Starch

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.931-932.68 ◽

2014 ◽

Vol 931-932 ◽

pp. 68-72

Author(s):

Komsun Temna ◽

Nitinart Saetung ◽

Anuwat Saetung

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Natural Rubber ◽

Cassava Starch ◽

Interfacial Interaction ◽

Morphological Properties ◽

Elongation At Break ◽

Cure Time ◽

The Difference ◽

Cure Characteristic

In this work, the sponge rubbers based on cassava starch masterbatch in latex phase with the difference technique (non-gelatinized and gelatinized cassava starch) were preformed. The cassava starch contents from 0 to 70 phr were also studied. The cure characteristic, mechanical and morphological properties were investigated. It was found that the scorch time and cure time were increased with an increasing of cassava starch contents in both techniques. The mechanical properties i.e., tensile strength, elongation at break and tear strength were decreased with an increasing of cassava starch contents, except 500% modulus. However, the sponge based on gelatinized technique gave the better mechanical properties than that of non-gelatinized cassava starch. The SEM micrographs of sponge NR from gelatinized technique were also able to confirm a good interfacial interaction between hydrophilic cassava starch and hydrophobic NR.

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

10.26434/chemrxiv.9971285.v11 ◽

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>

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The Effect of Organic Modificaition Method onto Montmorillonite on Mechanical Properties of Natural Rubber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.55-57.341 ◽

2008 ◽

Vol 55-57 ◽

pp. 341-344 ◽

Cited By ~ 1

Author(s):

Chanchai Thongpin ◽

N. Tangchantra ◽

P. Kaewpetch ◽

J. Dejkun ◽

A. Chartsiriwattana

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Natural Rubber ◽

Organic Molecule ◽

Elongation At Break ◽

Tear Strength ◽

Cure Characteristics ◽

Modified Montmorillonite

Montmorillonite is a type of clays that has been used to reinforce polymer including rubber. Therefore this research is aimed to modify mechanical properties of natural rubber (NR) using montmorillonite (MMT) comparing with the organic modified montmorillonite (CTAB-MMT) and organic molecule grafted MMT. The affect of MMT, CTAB-MMT and HTMS-g-CTABMMT on cure characteristics of NR were studied. It was found from the research that the increase of MMT content could prolong the scorch time whereas CTAB-MMT and HTMS-g-CTABMMT could shorten the scorch time. The cure times of the compounds in all cases were not much different. In term of mechanical properties, modulus, tensile strength and tear strength of NR/HTMS-g-CTABMMT vulcanizate were higher than those of NR/MMT and NR/CTAB-MMT vulcanizates. Meanwhile, elongation at break of the NR/ HTMS-g-CTABMMT vulcanizate decreased more than the latter cases

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Cure and Mechanical Properties of Natural Rubber Filled Bacterial Cellulose

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.705.40 ◽

2016 ◽

Vol 705 ◽

pp. 40-44

Author(s):

Chaiwute Vudjung

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Natural Rubber ◽

Bacterial Cellulose ◽

Elongation At Break ◽

Roll Mill ◽

Cure Time ◽

Mooney Viscosity

Natural rubber (NR) containing the nata de coco fiber or Bacterial cellulose (BC) was prepared by co-coagulation of BC and concentrated NR latex with CaCl2 and compounded by two roll mill. The effect of BC content was the important factor in this study. It was that found tensile strength and elongation at break of NR filled BC (NR/BC) decreased with increasing BC content. The addition of BC into NR affect Mooney viscosity of NR/BC masterbatch, with increasing BC content, scorch time and cure time of their compound decreased.

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Reinforcement of Natural Rubber with Quartz/Sericite/Wollastonite

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.239-242.2953 ◽

2011 ◽

Vol 239-242 ◽

pp. 2953-2957 ◽

Cited By ~ 1

Author(s):

Jun Fang Guan ◽

Hui Qun Yang ◽

Yan Qiang Yu ◽

Yang Chen ◽

Guo Bing Yang ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Natural Rubber ◽

Rubber Matrix ◽

Coupling Agents ◽

Mass Ratio ◽

Silane Coupling Agents ◽

Elongation At Break ◽

Tear Strength ◽

Parallel Arrangement

In the paper, ultrafine quartz, sericite and wollastonite modified with silane coupling agents KH-570 were incorporated into natural rubber(NR). The synergisitc effect on reinforcing NR caused by the three types of fillers was investigated under a same vulcanizing formulation and process. The mechanical properties and microstructure of the vulcanizates were conducted through mechanical testing and scanning electron microscopy(SEM). The results of mechanical properties tests showed that when one of these three fillers was loaded within NR alone, the tear strength and permanent set of NR vulcanizates filled with quartz could reach 27.61 kN m-1and 16.0%, respectively, stress at 300% elongation of NR vulcanizates filled with sericite could attain 4.69 MPa, and the tensile strength and elongation at break of NR vulcanizates filled with wollastonite could get to16.64 MPa and 951.21%, respectively. Under the condition that the filler loadings were 40 parts per hundred parts of rubber(phr), and the mass ratio of quartz, sericite, wollastonite was 1:1:3, the tensile strength and tear strength could come up to 17.33MPa and 27.54 kN m-1. The mechanical properties of NR composites filled with mixtures were found to be complemented by those three types of minerals. SEM results revealed that the fillers are well dispersed in the rubber matrix in the parallel arrangement with a densest stack, and the synergistic reinforcment effect of the fillers on NR was obvious.

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Effect of Oleic Acid on Properties of Natural Rubber Filled Bacterial Cellulose

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.744.295 ◽

2017 ◽

Vol 744 ◽

pp. 295-299

Author(s):

Saowaluk Boonyod ◽

Chaiwute Vudjung

Keyword(s):

Mechanical Properties ◽

Oleic Acid ◽

Natural Rubber ◽

Bacterial Cellulose ◽

Elongation At Break ◽

Tear Strength ◽

Cure Characteristics ◽

Roll Mill ◽

Cure Time ◽

Mooney Viscosity

Natural rubber (NR) containing the nata de coco fiber or Bacterial cellulose (BC) was prepared by co-coagulation of BC and concentrated NR latex with CaCl2 and compounded by two roll mill. The effect of oleic acid (OA) containing in NR filled BC (NR/BC) was the important factor in this study. BC was varied from 0–25 parts per hundred parts of rubber (phr), and the Mooney viscosity, cure characteristics and mechanical properties of NR/BC with and without OA as compatiblizer was evaluated. It was found that tear strength and elongation at break of NR/BC containing OA improved. The addition of OA into NR/BC affect vulcanization properties of NR/BC masterbatch that retard the cure time of their compound. Of all BC contents investigated, the vulcanized NR/BC at 10-20 phr of BC with OA shows the optimum tear strength and the morphology of the vulcanized NR/BC is improved by the addition of OA.

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Sisal Fiber/Natural Rubber Composites: Effect of Fiber Content and Interfacial Modification

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.410.63 ◽

2011 ◽

Vol 410 ◽

pp. 63-66 ◽

Cited By ~ 2

Author(s):

Wittawat Wongsorat ◽

Nitinat Suppakarn ◽

Kasama Jarukumjorn

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Natural Rubber ◽

Fiber Content ◽

Sisal Fiber ◽

Elongation At Break ◽

Interfacial Modification ◽

Natural Rubber Composites ◽

Fiber Treatment ◽

Cure Time

Sisal fiber/natural rubber (NR) composites were prepared by the incorporation of sisal fiber into NR at contents of 10-30 phr. Fiber treatment (alkalization) and adding maleic anhydride grafted natural rubber (NR-g-MA) were used to improve interfacial adhesion between sisal fiber and NR matrix. Mechanical properties, morphologies, and cure characteristics of the composites were studied. With increasing fiber content, modulus at 100% strain (M100), modulus at 300% strain (M300), and hardness of the composites increased whereas tensile strength and elongation at break decreased. Cure time of the composites decreased with increasing fiber content but scorch time was not much affected by fiber content. Alkali treated sisal fiber/NR composite exhibited higher tensile properties and hardness than untreated sisal fiber/NR composite at all fiber content due to the improved adhesion between fiber and NR matrix through the mechanical interlocking mechanism. Alkalization showed no effect on scorch time and cure time of the composites. The addition of NR-g-MA into the composites increased M100, M300, tensile strength, and hardness but prolonged scorch time and cure time. NR-g-MA provided more effective improvement of the mechanical properties of the composites when compared to fiber alkalization.

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