Relationship between stress relaxation behavior and thermal stability of natural rubber vulcanizates

Hayeemasae, Nabil; Masa, Abdulhakim

doi:10.1590/0104-1428.03120

Cited by 11 publications

(8 citation statements)

References 24 publications

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“…31 The thermal stability of all NR vulcanizate samples was estimated from the temperature at which the sample had lost 5% of its initial weight (T d5 ). 32 The T d5 of the NR shifted from ∼286°C to ∼334-338°C (by about 17-18%) for cyclized NR, depending on the degree of cyclization. In addition, the degradation of the NR shifted toward a higher temperature with increasing cyclization level in the entire tested range.…”

Section: Resultsmentioning

confidence: 94%

Influence of acid concentration on thermomechanical, tensile and thermal properties of cyclized natural rubber

Jaratrotkamjorn

Hayeemasae

Zakaria

et al. 2023

Journal of Elastomers & Plastics

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Properties of cyclized natural rubbers (NR) with various degrees of cyclization (∼4-22%) were investigated in this study. Prior to compounding with rubber additives, the cyclized rubbers were initially prepared by dropping various concentrations of acid (5-30 wt%) to the NR latex, followed by coagulation and drying. The results revealed that the degree of cyclization increased with acid concentration. Increased ring structure formation in the modified NR tended to increase the torque difference during crosslinking, as the cyclic ring structures acted as steric hindrances. The crosslink density was found to decrease with increasing cyclization level due to the loss of active sites for crosslink formation, increasing swelling capability of the cyclized rubbers. The 100% and 300% moduli, tensile strength and extensibility of the NR reduced with increasing degree of cyclization due to a reduction of crosslink density. As a result of cyclic structure formation and a reduction of unsaturated double bonds in the NR, the stability of cyclized NR at elevated temperatures was improved over the pure NR, in a manner dependent on the level of cyclization. Single glass transition temperature was seen in the NR while two glass transition temperatures were noticed in the cyclized NR. The thermal stability of 22% cyclized NR was 50°C higher than that of the pure NR and the aging properties of the cyclized NRs were also greater mainly due to a reduction of unsaturated double bonds. This suggests that cyclized NR may find applications in products requiring thermal resistance.

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Section: Resultsmentioning

confidence: 94%

Influence of acid concentration on thermomechanical, tensile and thermal properties of cyclized natural rubber

Jaratrotkamjorn

Hayeemasae

Zakaria

et al. 2023

Journal of Elastomers & Plastics

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“…On the other hand, the highest content of monosulfidic crosslinks in the vulcanizates obtained using EV facilitated their thermal stability compared to those with SEV and CV. It was due to the high thermal stability of monosulfidic linkages, which may retard both the scission of crosslinks and degradation of the elastomer main chain during decomposition 46,47 . Thus, it was concluded that both, the type of accelerator used, that is, the thermal stability of the accelerator, and the structure and content of the crosslinks in the elastomer network considerably affected the thermal stability of the vulcanizates.…”

Section: Resultsmentioning

confidence: 99%

Influence of accelerators and curing system composition on the cure characteristics, crosslinks structure and properties of acrylonitrile‐butadiene elastomer

Maciejewska

Sowińska‐Baranowska

2023

J of Applied Polymer Sci

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The goal of this work is to study the influence of the type of vulcanization accelerator and the quantitative composition of the curing system on the cure characteristics, morphology of elastomer network, crosslink density and physico-chemical properties of acrylonitrile-butadiene rubber (NBR) composites.Sulfur curing systems are investigated, which consist of various types of accelerators, that is, sulfenamide, guanidine and thiuram, applied in various proportions to sulfur. The type of accelerator and the sulfur/accelerator ratio significantly affect both the cure rate and the structure and number of crosslinks resulting from the vulcanization. The highest cure rate and the lowest content of polysulfidic crosslinks are exhibited by rubber composites with efficient (EV) curing systems due to the highest content of accelerators compared to semi-efficient (SEV) and conventional (CV) systems. The structure of crosslinks strongly affect tensile properties and hardness of the vulcanizates as well as their solvent resistance, thermal stability and resistance to thermo-oxidative aging.

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“…The unfilled NR compound also showed two degradation regions with an initial weight loss of volatile substances including stearic acid and moisture at 200°CÀ280°C, and a major weight loss related to the degradation of NR molecules at 350°CÀ465°C. 47 The T onset , T end set , and char residue of the NR vulcanizate were 353.8°C, 461.2°C, and 3.3%, respectively. From Figure 7(c) and (d), the DTG curves showed T max of WBL, FL, and NR compound at 331.5°C, 341°C, and 384.3°C, respectively.…”

Section: Tga Analysismentioning

confidence: 93%

Leather-like composite materials prepared from natural rubber and two leather wastes: Wet blue leather and finished leather

Raksaksri

Phunpeng

2022

Journal of Elastomers & Plastics

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In this study, leather-like composites were prepared from natural rubber (NR) and two different types of leather waste, namely wet blue leather (WBL) and finished leather (FL). Compounding was carried out on an internal mixer and two-roll mill, and curing was further conducted on a compression molding machine. The effects of leather type and content from 20 to 80 parts per hundred of rubber (phr) on cure characteristics, mechanical properties (hardness and tensile properties) and thermal stability of the as-prepared composites were investigated and compared with those of the unfilled NR compound. The curing rate and crosslink density of all composites were found to be lower than those of the unfilled NR. All WBL-filled NR composites exhibited higher tensile strength than the unfilled NR, while all FL-filled NR composites had lower values. Meanwhile, the hardness and modulus at 200% strain of all composites were increased with increasing leather waste contents compared to those of the unfilled NR. The composites containing low WBL loadings (20 and 40 phr) demonstrated higher elongation at break over the unfilled NR, while the other composites exhibited lower values. Besides, the thermal stability of all NR composites was deteriorated, but still largely retained.

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Relationship between stress relaxation behavior and thermal stability of natural rubber vulcanizates

Cited by 11 publications

References 24 publications

Influence of acid concentration on thermomechanical, tensile and thermal properties of cyclized natural rubber

Influence of acid concentration on thermomechanical, tensile and thermal properties of cyclized natural rubber

Influence of accelerators and curing system composition on the cure characteristics, crosslinks structure and properties of acrylonitrile‐butadiene elastomer

Leather-like composite materials prepared from natural rubber and two leather wastes: Wet blue leather and finished leather

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