An alternative antioxidant for sulfur-vulcanized natural rubber: Henna

2018 ◽  
Vol 51 (5) ◽  
pp. 440-456 ◽  
Author(s):  
Şehriban Öncel ◽  
Begüm Kurtoğlu ◽  
Bağdagül Karaağaç
Keyword(s):  
Natural Rubber ◽  
Physical And Mechanical Properties ◽  
Rubber Matrix ◽  
Synthetic Antioxidants ◽  
Oxidative Aging ◽  
Rubber Compounds ◽  
Sulfur Vulcanization ◽  
Short And Long Term ◽  
Temperature Scanning

Oxidative aging of natural rubber (NR) leads to the deterioration in the physical and mechanical properties. Using various antioxidants during compounding is a common way to improve the aging resistance of NR. The most widespread used antioxidants are phenolic and amine-based synthetic antioxidants and 2,2,4-trimethyl-1,2-dihydroquinoline in rubber industry. However, synthetic antioxidants cause some environmental problems during their production and tend to be replaced by natural alternatives. In this study, henna has been evaluated as a natural antioxidant in NR-based rubber compounds for efficient and conventional sulfur vulcanization systems. Performance of henna was evaluated in terms of rheological, mechanical, aging, and temperature scanning stress-relaxation properties of the compounds. It has been concluded that henna could be used as an alternative antioxidant for sulfur vulcanization of natural rubber matrix, compensating little deteriorations in vulcanizate properties. Short- and long-term performances of henna were also found to be related to vulcanization system.

scholarly journals Role of trade in natural rubber and palm oil in the composition of GDP in Ivory Coast

2020 ◽  
pp. 48-63
Author(s):  
Paul-Alfred Kouakou Kouakou
Keyword(s):  
Economic Growth ◽  
Natural Rubber ◽  
World Bank ◽  
Palm Oil ◽  
Ivory Coast ◽  
Ardl Model ◽  
Oil Exports ◽  
Augmented Dickey Fuller ◽  
Short And Long Term

Purpose. This paper discusses the effect of natural rubber and palm oil exports on economic growth in Ivory Coast from 1980 to 2016 using World Bank data. Methodology / approach. The analysis involved the use of Augmented Dickey-Fuller (ADF) and Phillips-Perron (PP) unit root tests and the ARDL model. Results. This paper discusses the effect of natural rubber and palm oil exports on economic growth in Ivory Coast from 1980 to 2016 using World Bank data. The analysis involved the use of Augmented Dickey-Fuller (ADF) and Phillips-Perron (PP) unit root tests and the ARDL model. The results of the study show that there is a positive and non-significant relationship between natural rubber exports and short-term economic growth. On the other hand, in the long term, they have a positive and significant influence on economic development. However, in the short and long term, palm oil exports have a positive and significant impact on gross domestic product. Finally, labour, investment and market opening have a positive and significant effect on economic growth in the short and long term respectively. Therefore, the Ivorian government needs to promote good agricultural practices and agricultural financing in order to increase the competitiveness of the Hevea –Oil palm sector. Originality / scientific novelty. Previous studies in natural rubber and palm oil focused mainly on its production, constraints to production and processing. However, very few studies on its effects on economic growth have been done so far. This study fills that gap. It expanded the existing literature and the subject of the causal relationship between natural rubber and palm oil exports and economic growth in Ivory Coast and shed light on required efforts to enhance the production and utilization of natural rubber and palm oil at larger scale to bring economic development in Ivory Coast. At last, the ARDL model is used to address this issue. Practical value / implications. The generated information will be useful to a number of organizations including: research and development, marketers, producers, policy makers, government and non-governmental organizations to assess their activities and improve their mode of operations, to help better guide the design and implementation of policies and strategies. Finally, knowing the existing relationship between natural rubber and palm oil exports and economic growth, together with impediments faced by natural rubber and palm oil exports, the study provides the various ways to improve these exports by increasing exports capacity of local producers. Research on this issue is too important to inform policymakers regarding resource allocation in the natural rubber and palm oil sector to achieve economic growth.

Properties of Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes

2015 ◽  
Vol 1109 ◽  
pp. 195-199 ◽  
Author(s):  
Abd Aziz Azira ◽  
Dayang Habibah Abangismawi I. Hassim ◽  
D. Verasamy ◽  
Abu Bakar Suriani ◽  
M. Rusop
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Natural Rubber ◽  
Considerable Increase ◽  
Physical And Mechanical Properties ◽  
Rubber Matrix ◽  
Rubber Composites ◽  
Transmission Electron ◽  
Maximum Conductivity ◽  
Polymer Latex

In order to achieve improvements in the performance of rubber materials, the development of carbon nanotube (CNT)-reinforced rubber composites was attempted. The CNT/epoxidised natural rubber (ENR) nanocomposite was prepared through latex technology. Physical and mechanical properties of the CNT/ENR nanocomposites were characterized in contrast to the carbon black (CB)/ENR composite. The dispersion of the CNTs in the rubber matrix and interfacial bonding between them were rather good; monitored transmission electron microscopy and scanning electron microscopy. The mechanical properties of the CNT-reinforced ENR showed a considerable increase compared to the neat ENR and traditional CB/ENR composite. The storage modulus of the CNT/ENR nanocomposites greatly exceeds that of neat ENR and CB/ENR composites and a maximum conductivity of about 1 S m-1 can be achieved. The approach presented can be adapted to other CNT/polymer latex systems.

The Oxidative Aging of a Compounded Natural Rubber Vulcanizate

1978 ◽  
Vol 51 (1) ◽  
pp. 1-6 ◽  
Author(s):  
R. A. Pett ◽  
R. J. Tabar
Keyword(s):  
Natural Rubber ◽  
Reaction Rate ◽  
Oxidative Degradation ◽  
Accelerated Aging ◽  
Zero Order ◽  
Elongation At Break ◽  
Oxidative Aging ◽  
Zero Order Reaction ◽  
The Impact

Abstract For the type of natural rubber compound used in the impact absorbing bumper system, it has been shown that an apparent zero order reaction rate is valid for the degradation of tensile strength, elongation at break and tear strength during oven aging. The zero order rate applies to aging times beyond an induction period and prior to the onset of hardening. Since the rates follow the Arrhenius equation for rate-temperature dependence, accelerated aging can be readily applied to the prediction of long term changes in properties (within the temperature range of 82–171°C). The magnitude of the activation energy determined from losses in mechanical properties indicates the dominance of oxidative degradation as the mechanism of the losses in properties.

scholarly journals Effect of Oxidative Aging on the Engineering Properties of DGAMs

2018 ◽  
Vol 7 (4) ◽  
pp. 50
Author(s):  
Al-Hadidy A.I. ◽  
Abdullah M. Rashed
Keyword(s):  
Service Life ◽  
Flexural Strength ◽  
Permanent Deformation ◽  
Engineering Properties ◽  
Base Layer ◽  
Short Term ◽  
Asphalt Cement ◽  
Oxidative Aging ◽  
Short And Long Term

Short and long term aging were conducted on the dense graded asphalt mixtures (DGAMs) containing 40-50 penetration grade asphalt cement binders. The short term oven aging (STOA) was conducted on loose mixtures at temperature of 135 °C for four hours and at temperature of 154 °C for two hours, whereas, the long term oven aging (LTOA) was conducted at temperature of 85 °C and at two periods of time between four and eight days. Marshall properties, tensile and compressive strength at 25 and 60°C, flexural strength at 0 and -10°C, cohesion at 60°C, tensile strength ratio, and index of retained strength were carried out on unaged and aged DGAM. A mechanistic-empirical design approach using BISAR program was adopted for estimating the improvement in service life of the pavement or reduction in thickness of DGAM and base layer for the same service life due to the aging of DGAM. The results showed that the STOA and LTOA: (1) increases resistance of DGAM against permanent deformation, stripping, and flexural strength; (2) increases traffic benefit ratio between 10 and 20%; (3) reduces the thickness of the surface layer between 8 and 14%; and (4) the base thickness reduces between 35% and 57%.

scholarly journals Microalgal biomass as renewable biofiller in natural rubber compounds

2021 ◽  
Author(s):  
Emanuela Bellinetto ◽  
Riccardo Ciapponi ◽  
Marco Contino ◽  
Claudia Marano ◽  
Stefano Turri
Keyword(s):  
Thermal Analysis ◽  
Carbon Black ◽  
Natural Rubber ◽  
Shear Fracture ◽  
Pure Shear ◽  
Rubber Matrix ◽  
Compression Moulding ◽  
Microalgal Biomass ◽  
Dynamic Mechanical ◽  
Rubber Compounds

AbstractMicroalgal biomasses, consisting of micronized Spirulina Platensis and its low protein fraction, were investigated in this work as possible renewable biofillers in natural rubber compounds, with the aim of replacing the commonly used carbon black. Natural rubber, in some cases blended with 10% of epoxidized natural rubber to improve the matrix-filler affinity, was compounded with 25, 35, 50 and 75 phr of each biomass. Compounds with 25, 35 and 50 phr of carbon black N990 were also prepared as benchmarks. After compounding, vulcanization times were determined by dynamic mechanical analysis. Rubbers were vulcanized by compression moulding and characterized by means of morphological analysis (scanning electron microscopy), thermal analysis (thermogravimetric analysis, dynamic mechanical thermal analysis) and mechanical tests (tensile tests, strain induced crystallization detection by X-ray diffraction, pure shear fracture tests). Microalgal biomass turned out to be homogeneously dispersed in natural rubber matrix and the materials obtained required lower curing times compared to carbon black compounds. It was found that, up to 50 phr, Spirulina has the ability to increase rubber tensile strength and modulus, acting similarly to N990, while decreasing rubber thermal stability and fracture toughness.

Comparative Study on Effect of Natural and Synthetic Antioxidants on Curing Characteristic and Properties of Different Natural Rubber Origin Compounds

2013 ◽  
Vol 812 ◽  
pp. 93-99
Author(s):  
N.H.H. Shuhaimi ◽  
Nadras Othman ◽  
Hanafi Ismail ◽  
S. Sasidharan
Keyword(s):  
Molecular Weight ◽  
Fatigue Life ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Processing Time ◽  
The Other ◽  
Synthetic Antioxidants ◽  
Compression Set ◽  
Rubber Compounds ◽  
Natural And Synthetic

Effect of natural and synthetic antioxidants on curing characteristic and properties of different natural rubber (NR) origin compounds were performed in this study. The evaluations of natural antioxidant (NA) performance in different NR origins were conducted and the changes in curing characteristic, crosslink density, fatigue life and compression set were recorded. The results indicated that Standard Thailand Rubber (STR) compound has longer processing time in curing characteristic due to a longer chain which is high molecular weight. Because of that, crosslink density, fatigue life cycle (Kc) and compression set (%) of STR compound show better result compared to other origins. On the other hand, NR compounds with NA have show better fatigue and compression set compared with trimethylquinoline (TMQ) especially for STR 5L. Thus, NA can be used as an alternative to the commercial antioxidant in all rubber compounds.

Effect of Compounding Ingredients and Crosslink Concentration on Blooming Rate of Natural Rubber Compounds

2015 ◽  
Vol 1134 ◽  
pp. 50-55 ◽  
Author(s):  
Ummu Qani’ah Yasin ◽  
Dzaraini Kamarun ◽  
Che Mohd Som Said ◽  
Azemi Samsuri
Keyword(s):  
Diffusion Process ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Crystalline Material ◽  
Rubber Matrix ◽  
Opposite Trend ◽  
Rubber Compounds ◽  
Rubber Surface ◽  
Different Types ◽  
High Peroxide

Blooming is a diffusion process whereby compounding ingredients dispersed in rubber matrix migrate to the rubber surface and appears as a layer of white crystalline material. Blooming is a typical phenomenon observed in rubber compounds which could lead to problems such as discoloration and poor appearance of products as well as loss of adhesion. Cause of blooming was still unclear and this research was carried out to identify the effect of compounding ingredients and crosslink concentration on blooming rate in natural rubber compounds. In this project 6 natural rubber formulations based on three different types of compounding ingredients at two different concentrations of crosslinker were compounded and tested for their blooming characteristics. Sulphur, wax and dithiocarbamate as the compounding ingredients were mixed with natural rubber in the presence of 1 and 6 phr of peroxide as the vulcanizing agents. The effect of crosslink concentration on blooming rate of the compounded rubber was then determined. The blooming rate was determined by the weight of the blooming material on the rubber surface as a function of time. The blooming rate was found to be affected by the types of compounding ingredients and crosslink density of rubber. Wax with 6 phr of peroxide showed the highest amount of bloom and the highest blooming rate while the dithiocarbamate accelerator with 1 phr peroxide showed the lowest amount of bloom and the lower blooming rate. As expected, all the compounding ingredients showed an increase of crosslink concentration as the loading of peroxide increases. The blooming rate was also found to be affected by the crosslink concentration of rubber. As the crosslink concentration increases, the rate of blooming increases as were shown by wax and dithiocarbamate accelerator. However, sulphur showed the opposite trend whereby the crosslink concentration increases but the blooming rate decrease. This could be due to the high peroxide level retarding the sulphur blooming process.

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