Papers by Keyword: Latex

Abstract: Cellulose is a natural polymer with good properties that have caught researchers' attention to utilize these natural resources' potential. Cellulose also has been widely used as an alternative filler to replace inorganic filler in polymer composites. This review discussed the extraction of cellulose from oil palm empty fruit bunch (OPEFB). This review focused on the OPEFB due to the emergence of palm oil plantations which creates a high amount of biomass, whereas OPEFB is one of the major contributors. The utilization of cellulose application in the polymer focused on alternative fillers in latex application. The postulate crosslink mechanism in latex films is also described to highlight the potential of OPEFB as fillers in latex application. The utilization of OPEFB cellulose has the potential to be explore as bio-fillers with also impact the crosslinks mechanism in latex system which can improved the properties in latex composites.

Abstract: Natural rubber latex (NRL) with the deproteinized process was interesting for cosmetic and transdermal drug delivery systems because of its notable characteristics. The purpose of this study was to develop in situ cooling films from deproteinized natural rubber latex (DNRL). Menthol, camphor, and volatile oils were added into DNRL emulsions for cooling effect and pain relief. The pH, rheological properties, particle size, and zeta potential of emulsions were examined. Then, the time of film-formation, morphology, and mechanical properties of the cooling NRL films were evaluated. The resultant emulsions revealed that their pH was about 5.7 - 6.3. The viscosity was in the range of 1000 – 3000 cps and indicated the pseudoplastic flow. The increasing amount of olive oil reduced the particle size and increased the negatively zeta potential of those emulsions. The film formation time of specimens was about 4.5 - 6.5 mins. The cooling films demonstrated smoothness and homogeneity. The presence of olive oil increased the softness of films. The increasing of oil volume increased the elasticity; however, it decreased the ductility of the films. This in situ cooling DNRL film was also effective forward for the development of a transdermal drug delivery system.

Abstract: Orthodontic elastic bands are commonly made from natural rubber because they provide high resiliency at a reasonable cost. However, hypersensitivity related to protein present in latex have been reported in some patients which has led to increased usage of non-latex elastic alternatives. Therefore, the assessment of their mechanical properties is of importance. The objective of this study was to compare the physical and mechanical properties of three commercial latex and non-latex type orthodontic elastic bands. Samples of latex and non-latex type orthodontic elastics from manufacturers – AO (6.5oz), MASEL (6.0oz), GAC (6.0oz), with 3/16-inch diameter were selected. Firstly, the physical characteristics (width, cross-sectional thickness, and inner diameter) of the elastic bands were determined, following which their mechanical properties [initial extension force (F0), 24 h-residual force (F24), percentage of force decay, force exerted at 3 times the inner diameter (F3xID) and breaking force] were tested. The data were analyzed with Mann-Whitney U test and multiple comparisons among the groups were done with Kruskal-Wallis Test (p< 0.05). Significant differences were found in the physical characteristics and mechanical properties among each brand and type of elastics. AO elastic bands had significantly low F0 and F24 compared with the others. While the percentage of force decay at 24 h was greatest in AO followed by MASEL and GAC. Non-latex type elastics showed greater force decay than latex type ones, approximately 30-40% and 20-30% of the initial force in non-latex and latex type elastic, respectively. AO elastics showed the highest F3xID and also the lowest breaking force. Overall, non-latex type elastics exhibited lower breaking force compared to latex type ones. Wide variations were observed in the physical and mechanical characteristics among same manufacturer and same elastic type. All commercial brands presented higher F3xID than that stated by the manufacturers. Non-latex type elastics showed greater force decay over 24 h than latex type ones. The differences in the properties between the 2 types of the elastics could be due to the differences in their structure and polymers composition.

Abstract: One aspect that needs to be considered in the application of asphalt pavement is the fact that asphalt is a non-renewable resource which requires constant maintenance throughout its lifetime. Thus, developing a mix with asphalt contents reduced to the minimum is a challenge in and of itself. Latex, in this case, would seem to be potentially viable additives. The aim of this research is to investigate the effects of using latex as an additive to minimize the use of asphalt in asphalt concrete wearing courses (ACWC). Four varying amounts of latex were mixed with asphalt at 0%, 2%, 4%, and 6% of the total weight of an asphalt binder. A wet process was then employed to blend the mixtures together. Afterward, the latex-asphalt mixtures were added to an aggregate to form various mixtures ranging from 5% to 7% of the aggregate and the incremental weight of 0.5% of the latex-asphalt ACWC. For each latex-asphalt-aggregate mixes, the optimum binder content was determined based on stability, flow, Marshall quotient, voids in the mineral aggregate (VMA), voids in the mixture (VIM) and voids filled by the binder (VFB). The results of this experiment indicated that the addition of latex reduces the need for asphalt contents.

Abstract: Natural rubber has an important role in many applications such as tyre products due to excellent elasticity and high friction causing wear on the tire and leading to energy dissipation in the form of heat and noise. Although reinforcing both inorganic and organic fillers can be a solution, it generally needs expensive coupling agent. Finding an excellent coupling agent by considering to environmentally friendly materials and economic aspect, is an interesting study. This study reported modification of natural rubber through copolymer grafting of starch onto natural rubber latex using Glow Discharge Electrolysis Plasma (GDEP) with varying of electrolyte. The experimental indicated that the electrolytes generally give significant effect to percent yield of the hybrid natural rubber-starch product. The highest percent yield is obtained from adding KCl. Addition of the divalent salts such as MgCl₂ and CaCl₂ disturbs the process due to reaction the salts with stabilizing system in natural rubber latex. Addition of NaOH is able to enhance the reaction performance with considering the radical elements recombination. The starch part as polar part and the natural rubber as non polar part building up the hybrid natural rubber-starch products, correlate with hydrophilicity and degradation of the both parts. This study results in the lowest contact angle of 54.8⁰, the highest percent yield of 8.6 %,, and the highest starch content in the product of 1.6%.

Abstract: Polystyrene-grafted natural rubber (PS-GNR) at various graft levels was evaluated to improve mechanical properties of natural rubber (NR). PS-GNR was synthesized by emulsion copolymerization at 60°C at different reaction times between 15 and 360 mins to control the grafting levels of PS in the PS-GNR co-polymer. The resultant PS-GNR co-polymers were then blended into NR latex. The vulcanized NR compounds were investigated for the effect of PS grafting percentage in PS-GNR/NR compounds on mechanical properties, including tensile, tear strength and hardness. A core-shell structure was revealed with PS encapsulating the NR core via transmission electron microscopy. The polystyrene grafting percentage was determined to be 12.7%, 17.1%, 22.1% and 23.6% for polymerization times of 15 min, 60min, 120min, and 360 min, respectively. Addition of PS-GNR into NR exhibited biphasic behavior, resulting in a decrease in the tensile strength and tear strength. With further increase in grafting percentage of PS, the tensile strength and tear strength continues to decrease. The rigid chain of PS grafted onto NR surface reduced the elasticity of NR chain resulting in lower tear strength and the tensile strength. Fracture surface revealed a decrease in ductility of material with increasing grafting percentage of PS. On the other hand, modulus and hardness of PS-GNR/NR compounds were found to increase with increasing grafting percentage of PS. The addition of PS-GNR to rubber compound had shown an impact on dynamic behavior. With further increase in grafting percentage of PS in PS-GNR, an enhancement of storage modulus of rubber compound was clearly observed.

Abstract: This paper demonstrates the feasibility of spent tea leaf (STL) fiber as an eco-friendly sound absorbing material. STL fiber is a by-product which was extracted from tea plant. STL are rich in polyphenols (tannins) which cause high resistance to fungal and termites, and high resistance to fire. In addition, STL are hollow and cellular in nature and thus perform well as acoustic and thermal insulators. Three different grades of STL were studied and the acoustic property was analyzed in terms of sound absorption coefficient and transmission loss. Experimental measurements of sound absorption coefficient in impedance tube are conducted. It was found that finest STL fiber grade exhibits better acoustic performance among others. Furthermore, the effect of latex binder on the acoustic property of STL fiber was also analyzed. Results suggest that the types of binder such as polyurethane and latex influenced the acoustic performance of STL fiber.

Abstract: The growing need for building material resources, and the requirements to preserve the environment, in a vision of sustainable development, has become necessary to study reinforcement techniques, using composite materials. Using local organic or inorganic materials in construction fields and public works is particularly important. Polymer mortar composites (PMC) are usually employed in the building industry as finishing materials, tile adhesive (mortar-adhesive) or façade coating. In repair applications, the addition of soluble polymer (latex) allows improving the adhesion properties of the materials used as coating. The use of mineral additives as partial substitutes for cement, in construction sites as well as in ready-to-use mortars, is an unknown practice in our country. For this reason, we thought it is crucial to study and assess the influence of these additions on the properties of cured composite. Supplementary cementitious materials (SCM) used in this study are silica fume and natural pozzolan, which necessarily need to be valorized.The present research work aims to use a specific experimental methodology that is able to identify the relationship between the degree of substitution by the mineral additives, the polymer and the modifications to the properties of fresh and hardened cement mixtures. Therefore, five PMC combinations were formulated from different percentages of additions, i.e. natural pozzolan (NP: 25%^w), silica fume (Sf: 5%^w) and polymer latex (P: 0, 5, 7.5, 10, 12.5 and 15%^w). Their durability factors, such as the porosity accessible to water and capillary absorption rate (sorptivity), were characterized, at different maturities. An attempt was also made to determine the thermal coefficients. The results obtained were compared with those of the reference mortars, made with Portland cement (CEMI). They showed that the decrease in porosity, sorptivity and thermal conductivity depends on the pair “SCMs/polymer”. But overall, the addition of polymer latex and pozzolanic additions have a beneficial effect on the durability and thermal properties of the composite materials.

Abstract: Degradation of building materials is an important phenomenon influencing their design and utilization. Mineral-based polymer-mortar composites (PMC) are often used as inexpensive promising materials to prevent the deterioration of constructions or remedy various reinforced concrete structures and they are used as materials for energy efficiency in buildings. In repair applications, polymer addition allows improving the adhesion properties of materials used in coating. With the intention of improving the sustainability of these composites, the influence of latex polymer and supplementary cementitious materials (natural pozzolan and silica fume) additions on the characteristics of these composites was investigated in aggressive media, such as acids. Mortars made with local pozzolanic mineral admixtures, obtained by substituting cement by different proportions of polymer (0, 5, 7.5, 10, 12.5 and 15%) were conserved in acidic solutions for 56 days. The microstructural analysis of these mortars was performed, using the X-ray diffraction technique, after 56 days of exposure to acid attack. The obtained results enable to bring out the beneficial effect of adding a latex polymer and other pozzolanic additives into modified materials on resistance to acid attacks. So, these composite materials can be recommended as materials for energy efficiency in buildings.

Abstract: Oriented strand boards are used to be designed as a water vapor retarder in timber structures. This article presents assessment of latex layer influence on oriented strands boards characteristics. Constructions with latex paint for increasing vapor resistance and constructions with a vapor-proof layer were also compared of indoor air parameters change. The values of hygrothermal properties were monitored in various levels of constructions. Full-scale experiments proved the difference of the humidity phenomena for latex painted boards.