Ribbed Smoked Sheet Research Articles

Assessing the Financial and Environmental Sustainability in Raw Rubber Processing; a Case Study with Ribbed Smoked Sheet Manufacture in Sri Lanka

Sri Lanka has been renowned for its top quality natural rubber products. Among the locally manufactured raw rubber types, ribbed smoked sheets (RSS) hold a significant position as it entails ca. 50% of total natural rubber production in island. With no sufficient information on effectiveness in the use of materials and finance and then environmental impacts of RSS manufacture, this study aimed at assessing RSS manufacturing process adopting Material flow analysis, Material flow cost accounting and environmental Life cycle assessment in three factories in view of providing effective suggestions for making the system to be more cost efficient and environmentally friendly. Results indicated that manufacture cost, financial loss and GHG emissions generated by processing 1 MT of RSS were LKR 104,004 ± 6,336, LKR 1,007 ± 44 and 38.0 ± 2.1 kg CO2e, respectively (mean ± standard error). As an improvement option, installing single-day smoke dryers was proposed. This option could reduce firewood consumption per 1 MT of RSS by ca. 30% resulting in 0.1% and 14% of reductions in manufacture cost and GHG emissions, respectively. Implications of these findings are also discussed.

Application of SARIMA model to forecasting the natural rubber price in the world market

This study was conducted to develop a forecasting model to predict the price natural rubber in the world market by using the Seasonal Autoregressive Integrated Moving Average (SARIMA). The dataset for model development was collected from series data of average monthly closing average prices in the natural rubber - Ribbed Smoked Sheet No.3 (RSS3) on the Tokyo Commodity Exchange (TOCOM) for the period of January 2007 - September 2018. The RSS3 price on the TOCOM provided the reference price for natural rubber in the world market. It resulted SARIMA(2,1,2)(1,1,1)12 model was selected as the best-fit model. The model achieved 0.000 for Probability value (P-value). 8.86 for Akaike Information Criterion (AIC) and 9.01 for Schwarz Information Criterion (SIC); 6.68% for Mean Absolute Percentage Error (MAPE) and 21.43 for Root Mean Square Error (RMSE). This model was used to forecast the world's natural rubber price during October 2018 - December 2020. This study may be helpful to the farmers, traders, and the governments of the world's important natural rubber producing countries to plan policies to reduce natural rubber production costs and stabilize the natural rubber price in the future, such as by setting suitable areas for natural rubber plantation in each country and defining appropriate and sustainable alternative crop areas in each country.

Estimation of air pollution from ribbed smoked sheet rubber in Thailand exports to Japan as a pre-product of tires

Ribbed Smoked Sheet (RSS) is one of the leading primary rubber products and is used as a raw material for tire production. An emission inventory (EI) analysis was conducted for the production and transportation of RSS in Thailand following the Life Cycle Inventory (LCI) methodology in order to highlight improvements needed to render the processes more environmentally friendly. The air emission inventory focussed on CO2, NOx, SOx, particulate matters (PM) and particle-bound polycyclic aromatic hydrocarbons (PAHs) using available databases, reports and previously published papers. Data was also obtained from a small-scale RSS factory, known as a cooperative, in Songkhla province, Thailand. Upstream para-rubber industries start from RSS in Thailand. Instead, downstream industries operate under tire production in Japan. There are high exported of RSS from Thailand to tire production in Japan. The material flow during the production and export of the amount of RSS produced and transported and the distances travelled were investigated. The results suggest that the tire production in Japan contributes more than 80% of the CO2 and 90% of the SOx emissions arising during the period from latex tapping to tire production. Conversely, 60% of PM and more than 90% of the PAHs were released from the drying process involving the wood-fuel burning without any pollution control devices. These results indicate that the environmental load due to hazardous air pollutants such as PAHs and smoke particles is serious in Thailand and has to be reduced to achieve environmentally sustainable tire production.

Sustainability and Competitiveness in Thai Rubber Industries

This article assesses the economic, legal and environmental conditions that Thai rubber farmers face and evaluates actions they can take to increase incomes.Statistical analyses determine relationships between prices of oil, natural and synthetic rubber. Pearson correlation tests found a strong positive relationship (r = 0.887) between the price of Brent crude and Thai ribbed smoked sheets, and a moderate positive relationship between price changes in Brent and synthetic rubber (r = 0.648). Regression analysis showed Brent oil price is a good predictor of natural rubber price. Moderate to strong positive relationships were also found between natural rubber price and the gross domestic products of Japan, China and the United States. Criminal antitrust behaviour in the rubber industries appeared to interfere with normal pricing in rubber markets. No significant bivariate correlation was found between rainfall in Thailand and natural rubber price, production or export, although fl ooding and other environmental issues clearly affected rubber farms. A survey of options showed that Thai rubber farmers can best improve their livelihoods through the collective purchase and use of new technologies and by integrating into downstream supplychain industries. At the very least, farmers are urged to abandon monocrop methods and supplement their incomes with fruit, fi sh, livestock or pigs.

Energy usage and greenhouse gas emissions associated with tea and rubber manufacturing processes in Sri Lanka

The objective of this study was to analyze the greenhouse gas (GHG) emissions associated with energy usage in tea and rubber industries in Sri Lanka. The scope of the study covered GHG inventory analysis of carbon dioxide, methane and nitrous oxide emissions associated with tea and rubber products, considering a life cycle approach starting from the plantations to the processed products. The functional units of tea and rubber products were ‘one metric ton of tea’ and ‘one metric ton of dry rubber content (DRC)’ respectively. Total GHG emission ranged from 514.27 ± 68.66 (high-grown) to 603.10 ± 191.58 (Uva) kg CO2e ton−1 of made tea and the emissions were not statistically significant (p > 0.05; ANOVA and Tukey's multiple comparison tests) among the four tea growing regions, namely, high-grown, mid-grown, low-grown and Uva regions. The electricity consumption contributed 63% of the GHG emissions in tea industry and the rest of the emissions were from fossil fuel (23%) and biomass (14%) usage. GHG emissions associated with rubber plantations were 155.6 ± 47.4 kg CO2e per ton of DRC. GHG emissions in raw rubber processing factories of crepe and ribbed smoked sheet (RSS), centrifuged latex and technically specified rubber (TSR) were 168.6 ± 44.1, 125.1 ± 24.8 and 375.60 kg CO2e per ton of DRC respectively. GHG emissions associated with latex based and dry rubber based industries were 1472.1 ± 1011.8 and 1801.23 ± 360.26 kg CO2e per ton of DRC respectively. The main source of GHG emissions in rubber industry was the use of grid electricity. GHG emissions associated with electricity usage in rubber plantations, crepe and RSS, centrifuged latex, TSR, latex based and dry rubber based industries were 15%, 80%, 42%, 53%, 75% and 52% respectively and the remaining emissions were from diesel, biomass, and fuel oil usage. Fuel switching in the manufacture of dry rubber based products has contributed to mitigation of GHG emissions by about 80%.

Improving Work System Design using Macro-Ergonomics Approach in Rubber Processing Plant

This study was conducted at an RSS (Ribbed Smoked Sheets) manufacturer in North Sumatra. In the preliminary observation, manufacturer encountered some problems such as machine breakdown (43 times in 2016 with 98 hours of downtime), scattered equipment, high temperature at all workstations, odor, disobedience against company regulations, and delay in product delivery. The aim of this research is to improve work design with variables such as machinery and equipment, physical environment condition, layout, working method, and organizational regulation, and worker with macro-ergonomic technique. There were 25 samples in total sampling technique used in this research and data collected through observation, open and closed questionnaire distribution to the respondent and measuring heat stress index felt by the worker. The results of the analysis showed two work design variables that had the highest severity, they are improvements to machinery and equipment variables by doing preventive maintenance while improving working environment conditions by installing turbine ventilator.

Sustainability and Competitiveness of Thailand’s Natural Rubber Industry in Times of Global Economic Flux

This study assesses economic, legal, and environmental conditions that Thai rubber farmers face, and evaluates actions they can take to increase incomes. Statistical analyses determine relationships between prices of oil, natural and synthetic rubber. Pearson correlation tests found a strong positive relationship (r = 0.887) between the price of Brent crude and Thai ribbed smoked sheets, and a moderate positive relationship between price changes in Brent and synthetic rubber (r = 0.648). Regression analysis showed Brent oil price is a good predictor of natural rubber prices. Moderate to strong positive relationships were also found between natural rubber price and gross domestic product of Japan, China, and the United States. Criminal antitrust behavior in rubber industries appeared to interfere with normal pricing in rubber markets. No significant bivariate correlation was found between rainfall in Thailand and natural rubber price, production, or export although flooding and other environmental issues clearly affected rubber farms. A survey of options showed Thai rubber farmers can improve livelihoods best through collective purchase and use of new technologies, and by integrating into downstream supply chain industries. At very least, farmers are urged to abandon monocrop methods and supplement incomes with fruit, fish, livestock, or pigs. stment budget, 2) architectural Aesthetic, and 3) utilization. Additionally, background of the interviewees is one of reinforcing factors for decision on universal design investment.

Spatial intelligent decision support system for increasing productivity on natural rubber agroindustry by green productivity approach

PurposeThe purpose of this paper is to develop a spatial intelligent decision support system (SIDSS) for increasing productivity in the rubber agroindustry by green productivity (GP) approach. The SIDSS was used to measure the productivity of rubber plantation and rubber agroindustry by GP approach, and select the best strategies for increasing the productivity of rubber agroindustry.Design/methodology/approachThis system was developed by combining spatial analysis, GP, and fuzzy analytic network process (ANP) with the model-based management system, which is able to provide comprehensive and meaningful decision alternatives for the development of natural rubber agroindustry. Rubber plantation productivity measurement model was used to find the productivity level of rubber plantation with fuzzy logic, and also to provide information and decision alternatives to all stakeholders regarding spatial condition of rubber agroindustry, production process flow, and analysis of the seven green wastes at each production process flow using the geographic information system. GP measurement model was used to determine the productivity performance of the rubber agroindustry with the green productivity index (GPI). The best strategy for increasing the productivity was determined with fuzzy ANP.FindingsRubber plantation measurement model showed that the average of plantation productivity was 6.25 kg/ha/day. GP measurement model showed that the GPI value of ribbed smoked sheet (RSS) was 0.730, whereas of crumb rubber (CR) was 0.126. The best strategy for increasing the productivity of rubber agroindustry was raw material characteristics control. Based on the best strategy, the GPI value of RSS was 1.340, whereas of CR was 0.228.Research limitations/implicationsThis decision support system is still limited as it is based on static data; it needs further development so that it can be more dynamically based on developments in the rubber agroindustry related levels of productivity and environmental impact. In addition, details regarding the decision to increase the productivity of the rubber section by benchmarking efforts should be studied further, both among plantation as well as among countries such as Thailand so that the productivity of rubber plantation and agroindustry can be integrated.Practical implicationsThis research can help the planters to select superior clones for rubber trees, to improve the technique of tapping latex, and to use a better coagulant. The good quality and quantity of raw material is a key factor in increasing the productivity of rubber agroindustry; if the quality of latex is good then the resulting product will also have a good quality and production cost can be reduced. In addition, the application of GP through the calculation of GPI value using improvement scenarios can be used as a reference and comparison for evaluating the performance of rubber agroindustry to reduce the waste generated by the activities of rubber processing plant.Social implicationsReduction of waste generated by production activities can improve the quality of life of the workforce and the environment. The calculation of GPI value can also be used as a basis to use raw materials, water, and electricity more efficiently.Originality/valueThis system was developed by combining spatial analysis, GP, and fuzzy ANP with the model-based management system, which is able to provide comprehensive and meaningful decision alternatives for the development of natural rubber agroindustry.

Colour Based Image Processing Method for Recognizing Ribbed Smoked Sheet Grade

This research proposes a colour based image processing technique to recognize the Ribbed Smoked Sheet (RSS) grade so that the RSS sorting process can be faster and more accurate than the traditional one. The RSS sheet image captured by the camera is transformed into grayscale image to simplify the recognition of rust and mould on the RSS sheet. Then the grayscale image is transformed into binary image using threshold value which is obtained from the RSS 1 reference colour. The grade recognition is determined by counting the white pixel percentage. The result shows that the system has 88% of accuracy. Most faults exist on RSS 2 recognition. This is due to the illumination distribution which is not equal over the RSS image.

Image Classification of Ribbed Smoked Sheet using Learning Vector Quantization

Natural rubber is an important export commodity in Indonesia, which can be a major contributor to national economic development. One type of rubber used as rubber material exports is Ribbed Smoked Sheet (RSS). The quantity of RSS exports depends on the quality of RSS. RSS rubber quality has been assigned in SNI 06-001-1987 and the International Standards of Quality and Packing for Natural Rubber Grades (The Green Book). The determination of RSS quality is also known as the sorting process. In the rubber factones, the sorting process is still done manually by looking and detecting at the levels of air bubbles on the surface of the rubber sheet by naked eyes so that the result is subjective and not so good. Therefore, a method is required to classify RSS rubber automatically and precisely. We propose some image processing techniques for the pre-processing, zoning method for feature extraction and Learning Vector Quantization (LVQ) method for classifying RSS rubber into two grades, namely RSS1 and RSS3. We used 120 RSS images as training dataset and 60 RSS images as testing dataset. The result shows that our proposed method can give 89% of accuracy and the best perform epoch is in the fifteenth epoch.

Assessing ecological footprints of products from the rubber industry and palm oil mills in Thailand

Rubber and crude palm oil (CPO) are the major agricultural products of Thailand. This work aimed at evaluating the ecological footprint (EF) of ribbed smoked sheet (RSS) from cooperative rubber sheet factories, ribbed smoked sheet bale (RSSB) from large rubber sheet factories, Standard Thai Rubber (STR) from block rubber factories, concentrated latex from concentrated latex factories, and CPO of palm oil mills in Thailand. The system boundary of cradle to gate was set according to the life cycle assessment approach. The fresh latex and cup lump from rubber plantations and fresh fruit bunch from the oil palm plantations were the major inputs for the rubber factory and the palm oil mill, respectively. EFs of the selected products from high to low were STR 20 at 7.06 global hectares (gha)/tonne, RSSB at 6.87 gha/tonne, RSS at 6.78 gha/tonne, STR 5 at 6.68 gha/tonne, concentrated latex at 5.07 gha/tonne, and CPO at 4.34 gha/tonne, on average. The EF of forest for production of fresh latex, cup lump and unsmoked sheet, and fresh fruit bunch accounted for more than 92% of the total EF. The EF for processing was quite less for the products of both rubber factories and palm oil mills. The production of RSS had a high potential for reducing the EF, followed by that of concentrated latex and STR, respectively. In 2015, the total EF for the production of rubber products and CPO in Thailand was 35.2 and 30.5 million gha for the average and best observed scenarios, respectively. The alternative methods for reduction of EF should be emphasized. The policy makers should include the EF values as the indicator for supporting the expansion of rubber and oil palm industries.

Greenhouse gas emissions from open-type anaerobic wastewater treatment system in natural rubber processing factory

We evaluated greenhouse gases (GHGs) emissions from an open-type anaerobic system (OAS) treating ribbed smoked sheets (RSS) wastewater in a processing factory. The emitted biogas comprised 57.7%–60.8% methane, 14.5%–31.5% carbon dioxide, 10.8%–24.7% nitrogen, and 329–423 ppm of nitrous oxide. In the OAS, the chemical oxygen demand (COD) degraded as the methane emission rate increased from influent to effluent. Finally, 94.4% of the total COD was removed. More than 90% of the removed COD converted to methane. Methane emitted from the bottom and the wall surface of the OAS. Methane-producing bacteria was detected by a cloning analysis of the 16S rRNA gene. The predominant species differed depending on the degradation characteristics of the RSS wastewater in the OAS. The emission rate of methane and nitrous oxide ranged between 2.58 and 8.85 NL/(m2 hr) and between 0.074 and 0.410 NL/(m2/hr), respectively. Moreover, 0.153 t-CO2eq of GHGs were emitted from 1 m3 of RSS wastewater treatment. Nitrous oxide accounted for 65% of the total GHGs emissions because of its high global warming potential. Therefore, both nitrous oxide and methane that emitted from the treatment of wastewater from a natural rubber processing factory must be considered as significant contributors to the GHGs.

Carbon Footprint of Rubber/Sugarcane Intercropping System in Sri Lanka: A Case Study

The global climate has been changing with the elevated CO2 in the atmosphere; hence identification of effective measures to mitigate or combat the adverse effects of climate change is at uttermost importance. The goal of Government of Sri Lanka (GoSL) for planting 40,000ha of rubber (Hevea brasiliensis Muell. Arg.) in the Uva province may partly address this issue sequestering the key greenhouse gas (GHG), CO2. Farmers in the area usually practice intercropping sugarcane (Saccharum officinarum) under immature rubber plants for extra income during the initial period of rubber cultivation. In the process of valuing rubber cultivation in mitigating the climate change effect, information on net greenhouse gas (GHG) emission from rubber/sugarcane intercropping system is required. Being scanty of such knowledge, this study was aimed to estimate the carbon footprint in the cultivation of rubber/sugarcane intercropping system in Sri Lanka.GHG emissions from the cultivation of rubber and sugarcane were calculated using the information available in the smallholdings having rubber/sugarcane intercropping in Monaragala district (IL2). GHG emission resulting from raw rubber processing, i.e. Ribbed Smoked Sheets (RSS) and Crepe Rubber (CR), was assessed using the data available in Kumarawatta Estate, Monaragala and Dartonfield Estate, Agalawatta, respectively. Also, GHG emission resulting from processing refined sugar was gathered from Palwatta Sugar Industries (Ltd), Monaragala. Carbon sequestration capacities of both crops were adopted from previous studies. Guidelines of Intergovernmental Panel on Climate Change (IPCC) were used in the estimation of carbon footprint. GHG emission in the process of cultivating rubber for its lifespan (30 years) was 65.15 CO2-eq ton/ha. When sugarcane was cultivated in rubber lands for four year period as a rubber/sugarcane intercropping system, GHG emission increased only by 9.72 CO2-eq ton/ha. Processing of RSS throughout the lifespan was responsible for additional 93.49 CO2-eq ton/ha emission whilst that for processing CR was limited to 50.14 CO2-eq ton/ha. Processing of refined sugar during four year intercropping period was accountable only for 0.62 CO2-eq ton/ha emission. In conclusion, carbon footprint (Net GHG emission) of cultivating rubber/sugarcane intercrop to produce CR and refined sugar was -1537.02 CO2-eq ton/ha/30yr whilst that for RSS and refined sugar was -1493.73 CO2-eq ton/ha/30yr. Increase in carbon footprint by intercropping sugarcane was only ca. 0.5% over mono cropping rubber. Potential application of this information in developing carbon trading projects is discussed.

Performance Evaluation of an Integrated Waste Water Treatment System for Ribbed Smoked Sheet Processing Waste Water with and Without Bio-dek in the Aeration Unit

Performance Evaluation of an Integrated Waste Water Treatment System for Ribbed Smoked Sheet Processing Waste Water with and Without Bio-dek in the Aeration Unit

Water scarcity footprint of products from cooperative and large rubber sheet factories in southern Thailand

The water scarcity footprints (WSF) of ribbed smoked sheet (RSS) from 14 cooperative rubber sheet factories (CRSF) in nine provinces in southern Thailand were evaluated. The WSF of ribbed smoked sheet bales (RSSB) was determined in two large rubber sheet factories (LRSF) in two provinces. Average values of consumptive water use (CWU) for RSS and RSSB were 549 and 592 m3/tonne, respectively. The CWU for both CRSF and LRSF was found to be very small in comparison to that for producing inputs from the rubber plantation. The CWU used for producing RSS arose from acquisition of fresh latex. Acquisition of unsmoked sheet and RSS had a major contribution for the RSSB production. WSFs of RSS and RSSB in terms of water deprivation ranged from 0.12 to 72.8 and 5.12 to 52.4 m3 water-equivalent/tonne, respectively. The major difference of CWU in the rubber plantations caused the difference of WSF for RSS and RSSB. The results of this study revealed that the policy makers should focus on the rubber plantation as the first priority. CWU and WSF values should be included as indicators for determining suitable areas of rubber plantation and for getting government support. In the factories, technologies or processes that used less water must be employed in the washing process to reduce CWU.

Evaluation of Ashley and Patterson model diagnostic tool in selection of ARCH/GARCH family models: case of natural rubber prices at the Colombo auction

There is a substantial amount of literature in favor of models in the ARCH/GARCH family as premier class of models for modeling financial and economic returns are of nonlinear form. However, there are many gaps in nonlinear model diagnosis and none of the nonlinearity tests are in wide acceptance. In this study, a new model diagnostic tool proposed by Ashley and Patterson in 2001 was identified as a useful diagnostic technique compared to other techniques in model selection. Moreover, it was found that the model diagnosis was straight forward with Ashley and Patterson test statistic (AP) when it is not straight forward with the use of other methods. Little work was found on the true process generating mechanism of returns of Ribbed Smoked Sheets No. 1 (RSS1) prices in the Colombo auction. In this study, by using AP, it was found that the true process generating mechanism of returns of RSS1 is nonlinear and the EGARCH (1,1) to be the most promising model that correctly generates returns of RSS1. Tropical Agricultural Research Vol. 25 (1): 109-119 (2013)

An Application of Analytical Hierarchy Process for Ranking Factors Affecting of Thai Natural Rubber Ribbed Smoked Sheets No.3 (RSS3) Price

The objectives of this research are to determine criteria and order of magnitude of the criteria affecting natural rubber prices of Thailand emphasizing on rubber ribbed smoked sheets No.3 prices (RSS3). The study began with the interview on the situation of natural rubber prices with the people from government, public, agricultural, and financial sectors who were relevant to Thailand rubber industry. The researcher asked for their suggestions on the significance of criteria affecting RSS3 prices. Questionnaire was used to verify the criteria. Analytical Hierarchy Process (AHP) was the instrument for sorting an order of magnitude of the criteria affecting RSS3 prices. Results indicated that there were 7 main criteria which affected RSS3 prices i.e. quantity of natural rubber, demand for natural rubber, currency exchange rate, crude oil price, world economic situation, Thailand’ situation, and advanced market speculation. The results reflected the criteria affecting the movement of RSS3 prices which were beneficial for predicting the tendency of RSS3 prices.

Effect of Various Extracted Solvent on DPPH Radical Scavenging Activity of Natural Rubber

Four types of extracted solvents i.e. mixtures of chloroform:acetone, chloroform:methanol, cyclohexane:acetone and cyclohexane:methanol, in the volume ratio of 4:1 were used to dissolve the natural rubber. Two grades of natural rubber i.e. air dry sheet (ADS) and ribbed smoked sheet No.3 (RSS3) were investigated. The rubber solution was purified by separated the rubber out with methanol. The non-rubber solution was then quantitative analyzed to verify 2,2-diphenyl-1-picryhydrazyl (DPPH) radical scavenging activity using Oxicount-Antioxidant kit test and also calculated the term of half maximal effective concentration (EC50). The plasticity retention index (PRI) was also investigated in order to compare the ageing properties of the rubber and their antioxidant activity. Furthermore, various rubbers i.e. ADS, RSS3 and Standard Thai Rubber 20 (STR20) were collected during early period of yearly tapping seasons to analyze the DPPH radical scavenging activity and EC50. It was found that the mixture of cyclohexane and methanol showed the highest DPPH radical scavenging activity and lowest EC50. RSS3 showed higher DPPH radical scavenging activity than that of ADS which the higher antioxidant activity also displayed the higher PRI values. It also found that during the early period of yearly tapping seasons, DPPH radical scavenging activity of RSS3 was found higher than that of ADS and STR20, respectively when extracted by mixture of cyclohexane and methanol.

Color and Antioxidant Changes in Various Natural Rubber Processes

Fresh field natural rubber was coagulated by acetic acid, soaked in water at room temperature (WRT) or 70°C (W70) for 1 hr, and then dried in an oven at 40°C. Non-soaked natural rubber samples (NoW) served as a control. Two grades of natural rubber, namely air-dry sheet (ADS) and ribbed smoked sheet No.3 (RSS3) derived from the same latex, were also investigated. All dry rubber samples were characterized with Lovibond colorimeter according to ASTM D3157, as well as with a HunterLab spectrophotometer. Furthermore, all the dry rubber samples were dissolved in a chloroform:methanol mixture (4:1 v:v). The rubber was then precipitated out of the solution with methanol, and the remaining solution was quantitatively analyzed for total phenolic content (TPC). The plasticity retention index (PRI) was determined for all the dried rubber samples according to ASTM D3194. It was found that WRT, W70 and ADS were similar in lightness L*, while RSS3 had the lowest L*. W70 had the lowest redness a*, which increased in the order WRT, NoW, RSS3 and ADS. W70 also had the lowest yellowness b*, which increased in the order RSS3, NoW and WRT and ADS. Moreover, TPC was the lowest for the W70 sample, increasing in the order ADS, WRT, NoW and RSS3. The PRI was highest for W70, and decreased in the order WRT, RSS3, NoW and ADS. All of the PRI values observed were comparatively high relative to blocked standard Thai rubber 20 (STR20).

Study on Preparation and Properties of Foam Rubber from Natural Rubber Ribbed Smoked Sheet Using Salt of Amino Alcohol and Carbonic Acid as Foaming Agent

This work was a study of the preparation and properties of foam rubber from natural rubber ribbed smoked sheet 3 (RSS3) using synthesized salt of amino alcohol and carbonic acid as foaming agent. The synthesised salts were varied in the amount of 0.25, 0.4, 0.6, 0.8, 1, 3 and 5 phr to compare with 0.4 phr of the commercial foaming agent (azodicarbonamide). The foam rubbers prepared through conventional vulcanization with sulfur were compounded by using a two-roll mill and formed into cylinder by a compression molding machine at 170°C for 7 min. The specimens were characterized including compressive stress, shape deformation and cellular morphology. SEM micrographs showed that the pore or cell content in foam rubber is higher with increasing the amount of salt while cell shape is bigger and more shapeless. However, cell distribution is constancy for all conditions. For the mechanical properties, the compressive stress of foam rubber increases with incresing the salt up to 1 phr and then decreases as well as porosity increases. Whereas, the dimension of all foam rubbers is shrunk over time. Therefore, this study indicated that the synthesized salt of amino alcohol and carbonic acid could create the cells into rubber and provided the size and shape of cell and the good mechanical properties competitive with commercial foaming agent.