Effect of vulcanization time on crosslink density and aging performance of natural rubber composites

2020 ◽  
Vol 62 (8) ◽  
pp. 858-862
Author(s):  
Ece Unur Yilmaz ◽  
Ahu Kor Dayioglu ◽  
Seda Balaban
Keyword(s):  
Natural Rubber ◽  
Crosslink Density ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Operating Conditions ◽  
Rubber Composites ◽  
Rubber Mixture ◽  
Natural Rubber Composites ◽  
Different Temperatures ◽  
Auto Parts

Abstract Natural rubber composites are widely used in the automotive industry because of their improved viscoelastic characteristics that are mostly governed by crosslink density. However, rubber parts suffer deterioration of performance over long service lives. Therefore, optimization of crosslink density and prediction of changes in physico-mechanical properties over time at elevated temperatures is extremely important for the production of safe auto parts. In this work, the effect of vulcanization time on crosslink density and thus the performance and lifetime of natural rubberbased auto parts was investigated. The natural rubber mixture prepared in this context was vulcanized for 3, 5, 10 and 15 minutes at a constant temperature of 160 °C. The crosslink density of each vulcanizite was determined by equilibrium swelling tests and the Flory-Rehner equation. The maximum crosslink density (10.75 × 10-5 mol × cm-3) and the minimum permanent compression set values (10 % at 70 °C and 25 % at 100 °C) were recorded for the sample vulcanized for 10 minutes (v10). Aging behavior of the samples were investigated by stress relaxation tests performed at 85 °C, 100 °C and 120 °C. The service lives of the vulcanizites at different temperatures were predicted by linear Arrhenius fits of degradation times. The sample vulcanized for 10 minutes (v10) was shown to exhibit a service life of 2282 hours at 70 °C in air and the optimum physico-mechanical performance under real operating conditions. The performance and lifetime prediction procedure used in this work could be employed in an early design of rubber components for specific applications.

PHASE-CHANGE MATERIAL: NATURAL RUBBER COMPOSITES FOR HEAT STORAGE APPLICATIONS

2020 ◽  
Vol 93 (1) ◽  
pp. 208-221 ◽  
Author(s):  
Minna Poikelispää ◽  
Sasu Ruokangas ◽  
Mari Honkanen ◽  
Minnamari Vippola ◽  
Essi Sarlin
Keyword(s):  
Natural Rubber ◽  
Phase Change ◽  
Thermal Energy ◽  
Elevated Temperatures ◽  
Storage Capacity ◽  
Heat Storage ◽  
Damping Properties ◽  
Rubber Composites ◽  
Good Ability ◽  
Natural Rubber Composites

ABSTRACT Global warming and environmental awareness in general have increased the research into thermal energy storage fields. Phase-change materials (PCMs) are efficient in storing thermal energy because of their high latent heat during the phase change. As the phase change is often based on the melting of the PCM, they need to be encapsulated, for example, by dispersing the PCM to a polymer matrix. In this study, the feasibility of the use of paraffin–natural rubber composites in applications requiring both the good ability to store heat energy and good vibration-damping properties is studied. This includes studies on PCM concentration and the microencapsulation of the PCM. It was found that the heat storage capacity increases with increasing PCM content, although the theoretical maximum capacity is not achieved because the PCM is released during vulcanization and the paraffin blooms. In addition, the loss factor was found to be increased at elevated temperatures, indicating improved damping properties. The encapsulation of PCM is found to have a positive influence on the heat storage capacity and the mechanical and damping properties of the rubber compound.

Comparison of Mechanical Properties and Curing Characteristics of Natural Rubber Composites with Different Coupling Agents

2013 ◽  
Vol 858 ◽  
pp. 24-31 ◽  
Author(s):  
Makara Lay ◽  
Azura A. Rashid ◽  
Nadras Othman ◽  
Yasuyuki Tezuka ◽  
Chhorda Pen
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Coupling Agents ◽  
Rubber Composites ◽  
Matrix Interaction ◽  
Curing Characteristics ◽  
Natural Rubber Composites ◽  
Silane Coupling ◽  
Colored Product

Nanosilica (NS) was recently used as a filler to improve mechanical properties, morphology behaviors of natural rubber (NR) composites and also for light colored product. NS is hard to disperse in NR composite compare to carbon black due to large number of Silanol (Si-OH) group leads to strong filler-filler interaction. Silane coupling agent was extensively used to improve reinforce efficiency of NS and also for good filler-matrix interaction by reducing Si-OH group. In this study, Bis[3-(triethoxysilyl)propyl] tetrasulfide (Si-69) and (3-aminopropy)triethoxysilane (APTES) were used as a coupling agents with various loading 1.5, 3, 4.5 phr in conventional sulphur vulcanization system. Both Si69 and APTES gave a significance of the NR compound processing. However, hardness was gradually decreased up to 4.5 phr due to plasticizing effect. Si-69 can increase crosslink density because of 4 molecular of sulphur (S) and its structure retarded the curing where APTES accelerated the cured because APTES has lower molecular weight and viscosity than Si-69.

Physical Properties of Rice Husk Fiber/Natural Rubber Composites

2011 ◽  
Vol 410 ◽  
pp. 90-93 ◽  
Author(s):  
Ladawan Srisuwan ◽  
Kasama Jarukumjorn ◽  
Nitinat Suppakarn
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Rice Husk ◽  
Crosslink Density ◽  
Morphological Properties ◽  
Rubber Composites ◽  
Elongation At Break ◽  
Natural Rubber Composites ◽  
Reinforcing Filler

In this study, rice husk fiber (RHF) was used as a reinforcing filler for natural rubber (NR). NR composites were prepared at various RHF contents, i.e., 10, 20, 30, 40 and 50 phr. Sulfur conventional vulcanization was used. Effect of RHF content on cure characteristics, mechanical properties and morphological properties of NR composites were investigated. The results showed that scorch and cure times of RHF/NR composites were not affected by increasing RHF content. Crosslink density, tensile strength, elongation at break and tear strength of NR composites slightly decreased with increasing RHF content whereas M100 and M300 of the composites slightly increased with increasing RHF content.

scholarly journals Functionalized Nanosilica for Vulcanization Efficiency and Mechanical Properties of Natural Rubber Composites

2021 ◽  
Author(s):  
Dileep Padmanabhan ◽  
Sinto Jacob ◽  
C.S. Julie Chandra ◽  
Midhun Dominic C.D ◽  
Poornima M P ◽  
...  
Keyword(s):  
Natural Rubber ◽  
High Performance ◽  
Morphological Analysis ◽  
Mechanical Performance ◽  
Cost Effective ◽  
Rubber Composites ◽  
Profound Influence ◽  
High Performance Polymer ◽  
Natural Rubber Composites ◽  
Cure Time

Abstract Accelerator functional character was introduced on nanosilica by the chemical reaction of sodium isopropyl xanthate (SIPX) with nanosilica (NS). Functional characteristics of nanosilica were confirmed by the Elemental analysis, thermogravimetric analysis, and infrared spectroscopy. This SIPX functionalized nanosilica (SIPX-NS) incorporated natural rubber (NR) compounds were used to evaluate the dispersion of silica in rubber and also the interaction between rubber and filler. The finely dispersed SIPX-NS particles in the NR matrix are revealed from the morphological analysis. Subtle changes in surface chemistry of silica had a profound influence on the dispersibility in NR matrix. NR 4SIPX-NS composite exhibited improved cure time, tensile strength, flex crack resistance and aging resistance relative to those of NR NS composite. This simple, efficient and cost-effective surface modification of silica improved the vulcanization efficiency and mechanical performance of NR composites and has great potential in the fabrication of high-performance polymer composites.

Effect of coir fiber reinforcement on mechanical properties of vulcanized natural rubber composites

2018 ◽  
Vol 25 (3) ◽  
pp. 517-528 ◽  
Author(s):  
Yogesh Patil ◽  
Sumit Sharma
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Fiber Reinforcement ◽  
Maximum Load ◽  
Coir Fiber ◽  
Rubber Composites ◽  
Aging Test ◽  
Natural Rubber Composites ◽  
Aging Resistance ◽  
Different Temperatures

Abstract In this study, the effect of coir fiber reinforcement on the mechanical properties of vulcanized natural rubber composite has been studied. An attempt has been made to predict the effect on tensile strength, maximum load, and elongation at break (%) of coir fiber-reinforced vulcanized natural rubber composites under cold, heat, and water aging tests. The natural rubber was vulcanized at 150°C. The fibers were soaked in a 5% solution of NaOH for 48 h at room temperature. At different temperatures, cold, heat, and water aging resistance tests were conducted to understand the behavior of the composite under different environment. The properties recorded after aging tests were compared with initial properties to investigate the effect of fiber reinforcement. The results revealed that the samples containing coir fiber showed better performance after each aging test. The specimens showed the highest properties in case of water aging resistance.

CNT@NiO/natural rubber with excellent impedance matching and low interfacial thermal resistance toward flexible and heat-conducting microwave absorption applications

2021 ◽  
Author(s):  
Maofan Zhou ◽  
Gengping Wan ◽  
Pengpeng Mou ◽  
Shengjie Teng ◽  
Shiwei Lin ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Thermal Resistance ◽  
Microwave Absorption ◽  
Impedance Matching ◽  
Interfacial Thermal Resistance ◽  
Heat Conducting ◽  
Rubber Composites ◽  
Natural Rubber Composites

Herein, CNT@NiO/natural rubber composites were fabricated to apply as flexible and heat-conducting microwave absorption materials.

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