Concentrated Latex Research Articles

Publisher Correction: Properties of vulcanised concentrated skim natural rubber latex dipped film

Publisher Correction: Properties of vulcanised concentrated skim natural rubber latex dipped film

Development of waterborne epoxy-based resin incorporated with modified natural rubber latex for coating application

Water-based coating has gained much attention globally due to environmental issues. This work aims to develop a waterborne epoxy coating incorporated with modified natural rubber (NR) latex for improved performance. For this purpose, the NR latex was modified into three types of low molecular weight epoxidized natural rubber (LENR) latex. The waterborne epoxy resin was prepared by simply mixing the epoxy resin with an amine curing agent in water and various LENR latex contents (10 to 50 wt%). The waterborne epoxy/LENR blend was coated on a tin substrate and the cured coating demonstrated better adhesion and bending properties than the neat epoxy. Phase morphological properties displayed a rough surface with a heterogeneous surface structure of the dispersed rubber and epoxy matrix. Two glass transition temperatures were observed, corresponding to the rubber modifier and the epoxy matrix. The mechanical properties of the thermosetting epoxy/LENR blends were assessed, revealing a maximum increment in elongation ability by approximately 370% for adding 50 wt% LENR, compared to the neat epoxy. These results hold the potential avenue for utilizing NR-based material in the waterborne epoxy-based resin for coating applications. Furthermore, it contributes to the NR, a renewable and eco-friendly material, in the coating technology, embracing a sustainable future.

Life cycle assessment (LCA) and economic analysis of two-stage anaerobic process of co-digesting palm oil mill effluent (POME) with concentrated latex wastewater (CLW) for biogas production

This study outlines the results of a process-based life cycle assessment (LCA) of the environmental performance of biogas production from co-digestion of palm oil mill effluent (POME) and concentrated latex wastewater (CLW) in the two-stage anaerobic digestion (AD) process. Biogas is utilized global across several sectors, including electricity generation, heating, and transportation. The Open LCA 2.0.2 software was used to evaluate the LCA at the midpoint level by using 18 different impact categories. This study reveals the three main contributions of the AD process, which were global warming (8.65 × 102 kg CO2eq), water consumption (5.32 m3), and land use change (3.39 × 102 m2 a crop eq), this result corresponded with the previous study in Malaysia that examined biogas production from the AD of POME In addition, alternative scenarios, in which a single substrate, have been established to quantify the impacts of potential improvements of biogas production to compare with base scenario of co-digestion. The results show that the environmental impacts of the base scenario released were lower than those of the single POME substrate of alternative scenario 1 in most impact categories. Furthermore, economic analysis is a crucial factor in the practical implementation of the AD process. Linking LCA with economic analysis offers a comprehensive perspective on sustainability, balancing environmental impacts with financial performance to optimize the potential of the AD co-digestion process. This is the first study to apply LCA and economic analysis to this specific co-digestion process in a two-stage AD system. The economic analysis of the two-stage AD of co-digesting POME and CLW was 1200 m3/d production of wastewater (70 % of POME and 30 % of CLW) based on the factories' data. The result indicates net present value, internal rate of return, and payback period of 515,813.94 USD, 9.13 %, and 8.87 years, respectively. This work proposed the potential approach for implementing the two-stage AD co-digestion of POME and CLW while concurrently producing valuable bioenergy carriers.

Properties of vulcanised concentrated skim natural rubber latex dipped film

Properties of vulcanised concentrated skim natural rubber latex dipped film

Advancement of an Environmentally Friendly and Innovative Sustainable Rubber Wrap Film with Superior Sealing Properties.

Common kitchen wraps like plastic and aluminum foil create significant environmental burdens. Plastic wrap, typically made from non-renewable fossil fuels, often ends up in landfills for centuries, breaking down into harmful microplastics. Aluminum foil, while effective, requires a large amount of energy to produce, and recycling it at home can be impractical due to food residue. A promising new alternative, low-nitrosamine rubber wrap film, aims to reduce waste by offering a reusable option compared to traditional single-use plastic wrap. The film is environmentally friendly, durable, and effective in sealing containers and keeping food fresh or crispy. The raw materials used to make the product were studied, namely fresh and concentrated natural rubber latex. No nitrosamines were found in either the fresh or concentrated latex, which is important as nitrosamines are known to be carcinogenic. The absence of nitrosamines in the raw materials suggests that the universal rubber wrap film is safe for use. In this study, the rubber formulation and properties of rubber used to make rubber wrap film were studied. The content of additives affecting the rubber properties was varied to find the optimum rubber formulation for making rubber wrap films. The rubber formulation with the least amount of chemicals that met the following criteria was selected: tensile strength of at least 15 MPa, elongation at break of at least 600%, and nitrosamine content below 6 ppm. It was found experimentally that the optimum rubber formulation for making a translucent rubber film had 0.7 phr zinc oxide and 1.0 phr sulfur. Performance tests revealed the rubber wrap film's superior sealing capabilities. Its elasticity allows for a tighter fit on containers, effectively conforming to various shapes and creating an optimal seal compared to plastic wrap and aluminum foil. The results of this study provide valuable information for developing a universal rubber wrap film that is safe with low nitrosamines.

Design and development of a system based on transient hot wire technique to determine dry rubber content in natural rubber latex

Design and development of a system based on transient hot wire technique to determine dry rubber content in natural rubber latex

Biological activities of fig latex -loaded cellulose acetate/poly(ethylene oxide) nanofiber for potential therapeutics: Anticancer and antioxidant material

Cancer is a fatal disease, and unfortunately, the anticancer drugs harm normal cells. Plant's extracts are the golden key to solving this issue. In this research, fig latex - from Ficus carica- was encapsulated using cellulose acetate (CA) and poly (ethylene oxide) (PEO) polymers via electrospinning method (Fig@CA/PEO). Fig@CA/PEO nanofiber scaffold was characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The average fiber diameter was decreased with an increase in latex concentration from 715 nm to 583 nm. FT-IR spectroscopy indicated the presence of fig latex in Fig@CA/PEO nanofibers. Compared to 5-fluorouracil, Fig@CA/PEO nanofiber scaffold considered safe towards normal cells (WI-38). Moreover, the nanofiber scaffold was efficient against colon cancer cells (Caco) and liver cancer cells (HepG2) as it demonstrated IC50 values for cells by 23.97 μg/mL and 23.96 μg/mL, respectively. Besides, the nanofiber scaffold revealed mechanistic variations in apoptotic oncogenes; described by the upregulation of BCL2 and P21, combined by downregulation of p53 and TNF. Moreover, the nanofiber scaffold showed antioxidant activity counting 33.4, 36 and 41 % of DPPH scavenging as the fig latex concentration increased. The results demonstrate that the Fig@CA/PEO nanofiber scaffold is a promising substitute to traditional chemotherapy.

Preparation and characterization of long carbon chain based polyacrylate latexes and their pressure sensitive adhesive application

Aqueous emulsion homo- and co-polymerization of lauryl methacrylate (LMA), a strong hydrophobic monomer with long carbon chain, is quite challenging. In this study, a long carbon chain emulsifier N-390 was used as the primary emulsifier to facilitate the emulsion copolymerization of LMA with other acrylate monomers through the mutual hydrophobic interaction between N-390 and LMA, and ultimately polyacrylate latex pressure sensitive adhesives modified by LMA via pre-emulsified semi-continuous seeded emulsion polymerization process were synthesized. The effects of LMA on the resulting latex and PSA properties was comprehensively examined. Both FTIR and 1H NMR spectra indicated that LMA has been successfully introduced into copolymer chain with the aid of long carbon chain emulsifier N-390. The results also showed that the introduction of LMA will contribute to decrease in particle size and zeta potential, while increase viscosity and gel content of the acrylate PSA latex. Moreover, as the LMA content increased, the latex PSA films demonstrated gradual improvements in both water resistance and thermal stability. Finally, for the long carbon chains adhesive film, the shear strength was improved greatly while at the sacrifice of loop tack and peel strength, when compared to counterparts without LMA.

Latex, colloidal and film properties of concentrated skim latex prepared using membrane filtration process

Latex, colloidal and film properties of concentrated skim latex prepared using membrane filtration process

Silkworm cocoon-inspired and robust nanofibrous composite separator with gradient structure for lithium ion batteries

Considering electrospun nanofiber-based membranes that generally exhibit high porosity but poor mechanical property, there is a growing need to fabricate nanofibrous separators with comprehensive performance for lithium-ion batteries (LIBs). Silkworm cocoon, a source of design inspiration from nature, comprises a multilayer structure with composition change in the thickness direction, thereby endowing the cocoon with relatively high porosity and outstanding mechanical strength. Therefore, a silkworm cocoon-like structured nanofibrous separator (GPS) is fabricated in this work by initially preparing several polyacrylonitrile (PAN) nanofibrous membranes with varied content of carboxyl styrene butadiene latex (SBR) and then laminating them in a concentration gradient sequence. Compared with the pristine PAN membrane, the GPS exhibits comparable porosity, thermal stability and electrolyte wettability due to the existence of PAN nanofibers, while the tensile strength and puncture resistance of the GPS are greatly raised by 5.5 times and 1.5 times, respectively. On account of the structure design, GPS also shows better mechanical strength than PAN/SBR separators without concentration gradient, and the strengthening mechanism has been verified by the finite element analysis. Meanwhile, such gradient structure of GPS renders the battery with desirable ion transport ability and stable cycle properties. Thus, the silkworm cocoon-like structured separator could be a promising separator candidate for LIBs, and the bioinspired design in structure will play an increasingly important role in the development of high-performance battery in the future.

Studying the influence of additives of cationic latex and basalt fiber on the calculated characteristics of stone-sand mixtures made of iron tailings reinforced with cement

Problem. As a major industrial solid waste, iron tailings not only occupy a lot of agricultural land, but also pollute the environment. It is necessary to study the effect of adding different concentrations of aqueous cationic latex and different lengths of basalt fibers to the composition of crushed stone-sand mixtures of iron tailings and cement on the parameters of flexural ultimate tensile strength and the characteristics of the modulus of elasticity calculation. Goal. The effect of additives of aqueous cationic latexes of different concentrations and basalt fiber of different lengths in the composition of crushed stone-sand mixtures of iron tailings with cement on the flexural tensile strength and the elastic modulus as design characteristics was investigated. Methodology. The first stage of the study was to determine the effect of the content of two cationic latexes on the values of the tensile strength in flexion and the elastic modulus of the material from CSM-40 made of iron tailings reinforced with cement. The content of Butonal NS 198 and Butonal 5126 latexes in the composition of CSM-40 was 0, 3, 5, and 10 % by weight of the optimal amount of water at the maximum density of the mixture with cement. At the second stage, the influence of the length of basalt fibers at their content of 0.05 % by weight of the crushed stone and sand mixture on the values of the flexural tensile strength and the elastic modulus of the material from the cement-reinforced iron tailings CSM-40 was studied. It has been established that the addition of cationic latexes of the Butonal series to the composition of crushed stone-sand mixtures of iron tailings with cement causes a moderate increase in the values of the flexural tensile strength and the elastic modulus, compared to the material without the addition of latexes. Experimentally, a more significant increase in the values of the flexural tensile strength and elastic modulus of fiber-reinforced materials made of crushed stone-sand mixtures of iron tailings with cement was found compared to materials modified with cationic latexes. Conclusions:1.When the latex content is 5% (equivalent to the critical concentration of micelle formation in aqueous solution), the flexural tensile strength can be increased by a maximum of 14-15%. Under similar conditions, the elastic modulus value increases by 12-18%. 2.The addition of 0.05% (by weight) basalt fiber to the crushed stone and sand mixture of rust-colored quartzite reinforced with cement improves the bending strength and elastic modulus values compared to the non-fiber material. The largest increases in flexural tensile strength (18.5%) and elastic modulus (27.1%) are for materials with basalt fiber lengths of 18 mm.

Research on the production technology of rubber epoxy from concentrated natural rubber latex

The results of research on epoxidation technology from concentrated natural rubber latex (CNRL) and in-situ peroxyformic acid, which is synthesised from formic acid (FA) and hydrogen peroxide (HP), are presented in the article. The study investigated the influence of technological parameters of the epoxidation process, such as stabiliser content (nonylphenol ethoxylate, NP9), dry rubber content (DRC), isoprene, stirring speed, reaction time, reaction temperature, and molar ratios of hydrogen peroxide and isoprene (IP), on the epoxy resin content of the product. Research results have shown that the epoxidation reaction with NP9 at 10% takes from 2.5 to 20 hours under the following conditions: latex composition contains from 16 to 24% DRC, stirring speed 100 rpm, reaction temperature response 30 to 70 °C, HP/IP molar ratio changes from 0.7 to 1.3, FA/IP ratio is 0.2, the product was stable and without coagulation. The product was obtained with an epoxy content of 23.4 to 43.6%. This is the basis for building an epoxidized natural rubber (ENR) production process to create a series of natural rubber products that are renewable, environmentally friendly, low-cost, and have many industrial applications.

Facile Access to High Solid Content Monodispersed Microspheres via Dual-Component Surfactants Regulation toward High-Performance Colloidal Photonic Crystals.

Monodispersed microspheres play a major role in optical science and engineering, providing ideal building blocks for structural color materials. However, the method toward high solid content (HSC) monodispersed microspheres has remained a key hurdle. Herein, a facile access to harvest monodispersed microspheres based on the emulsion polymerization mechanism is demonstrated, where anionic and nonionic surfactants are employed to achieve the electrostatic and steric dual-stabilization balance in a synergistic manner. Monodispersed poly(styrene-butyl acrylate-methacrylic acid) colloidal latex with 55wt% HSC is achieved, which shows an enhanced self-assembly efficiency of 280% compared with the low solid content (10wt%) latex. In addition, Ag-coated colloidal photonic crystal (Ag@CPC) coating with near-zero refractive index is achieved, presenting the characteristics of metamaterials. And an 11-fold photoluminescence emission enhancement of CdSe@ZnS quantum dots is realized by the Ag@CPC metamaterial coating. Taking advantage of high assembly efficiency, easily large-scale film-forming of the 55wt% HSC microspheres latex, robust Ag@CPC metamaterial coatings could be easily produced for passive cooling. The coating demonstrates excellent thermal insulation performance with theoretical cooling power of 30.4W m-2, providing practical significance for scalable CPC architecture coatings in passive cooling.

Mass Transfer in Emulsion Polymerization: High Solids Content Latex and Mixing Effects

AbstractThe impact of different agitator configurations used during the emulsion polymerization of vinylidene fluoride (VDF) is studied with the goal of achieving a solids content of 55 wt% while minimizing particle coagulation and maintaining low levels of surfactant. The design and number of impellers, their spacing and the agitation speed are shown to have a strong influence on the transfer of gaseous monomer to the aqueous phase, and thus the rate of polymerization. Increasing the number of impellers on the central shaft, and decreasing the spacing of the impellers close to the latex surface has a strong influence on the ability to incorporate gaseous monomer, so the solids content and the latex level in the reactor increased. Furthermore, it is found that changes in the agitation rate during the reaction is necessary at high solids content to avoid destabilizing the particles in view of the low surfactant concentrations used.

Pyrolysis of Latex Sediment from Concentrated Latex Industry and Properties of Pyrolytic Products

Concentrated latex is an intermediate rubber product in Thailand. It is an important industry that generates income for the country and Its southern region. The main products of the latex factory were concentrated latex and skim blocks. The industrial waste from the concentrated latex factory is called latex sediment. It appears to be a white mixed light-yellow sludge or a dark brown color, contains magnesium compounds, and phosphorus is an important element. Therefore, finding appropriate measures for rubber production and environmentally friendly industrial waste management is important. Therefore, this study investigates the pyrolysis of latex sediment as an alternative to industrial waste management. Pyrolysis of 100 g of latex sediment was performed at 300 °C, 500 °C, and 700 °C. From the experiment, it was found that the properties of the liquid product from the pyrolysis process at 500 °C were alkaline, with a pH of 9.45. However, acetic acid was the highest amount of organic substance in the liquid product. Substances in the amine and amide groups were also observed, a base result for the liquid product exhibiting an alkaline value. The pH is an important factor in the decomposition of organic substances under anaerobic conditions. Therefore, a 1 wt% liquid product was used in a volume of 13.5 mL, which is the most appropriate amount because it uses the least amount of liquid product to adjust the alkalinity of the skim latex serum before entering the anaerobic fermentation system. Pyrolysis is an environmentally friendly option for managing factory latex sediments for sustainable production and creating a good image for the organization.

Characterization and Development of Venipuncture Practice Rubber Model Based for BCG Economy Framework

The Bio-Circular-Green (BCG) economy framework, which integrates economic, social, and environmental aspects for waste management, holds great promise for fostering growth across various sectors in Thailand. Venipuncture, a critical medical procedure, can lead to complications if not performed correctly. This study uses Thailand para latex resources and calcium carbonate extracted from recycled mollusk shells to develop an educational innovation model for venipuncture procedures. Natural rubber latex (NRL) was obtained from Chiang Rai, Thailand. Preserved latex was heated to obtain 60% concentrated latex, then combined with a sulfur solution, and calcium carbonate powder was added in various ratios. Molding used a specialized mold replicating anatomical features of the antecubital fossa, incorporating three prominent veins. The venipuncture practice rubber model was characterized for pH, moisture content, water absorption, tensile strength, and other properties. The model exhibited neutral pH, low moisture content, and notable resistance and elasticity. This study promotes the sustainable utilization of natural latex resources and recycled mollusk shells in developing innovative medical models within the BCG framework. Additional research is required to enhance the human friendliness and realism of the rubber material used in the venipuncture practice model.

Design and development of an herbal anti-arthritic gel incorporating Alstonia scholaris latex

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease leading to bone and joint damage. The current study reports the development of an herbal anti-arthritic gel formulation incorporating the latex of Alstonia scholaris (AS). Six batches of topical herbal gels (G1-G6) were formulated by dispersion method using different concentrations of AS latex (0.5 % to 3.0 % w/w) in Carbopol 934 (1.5% w/w) gel base. The gels were evaluated for various physicochemical properties using standard methods and G4 was selected as an optimized formulation based on the desirable properties of a topical gel. The in vivo anti-arthritic potential of G4 was evaluated using a complete Freund’s adjuvant (CFA)-induced arthritic rat (Sprague Dawley) model for 28 days. Assessment of various arthritic parameters including hematological and biochemical parameters and radiography of hind legs in arthritic rats was carried out. The developed herbal gels were found to be uniform and stable. The G4 gel formulation showed a maximum drug release of 95.22% following Higuchi kinetic model. The topical application of G4 gel exhibited significant (p<0.05) anti-arthritic activity compared to diseased rats. The herbal gel G4 effectively restored the arthritic, hematological and biochemical parameters in arthritic rats. Radiographic analysis demonstrated its ability to reduce soft tissue swelling and thus prevented bone degeneration and the narrowing of joint spaces. These results supported that the developed herbal gel may offer a novel therapeutic approach in the treatment of RA with fewer side effects, good patient compliance, high efficacy, and low cost.

Implementing miniemulsion photopolymerization for synthesis of waterborne biobased poly(thioethers) coatings

Herein, miniemulsion photopolymerization is implemented as a useful tool for synthesis of waterborne poly(thioether) dispersions from biobased monomers isosorbide-based dithiol (3R,3aR,6S,6aR)-hexahydrofuro[3,2-b]furan-3,6-diyl bis(3-mercaptopropanoate) and diallyl (3R,3aR,6S,6aR)-3,6-bis(allyloxy)hexahydrofuro[3,2-b]furan and their combination with the petroleum-based dienes diallyl terephthalate, 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5]undecane, and 1,4-bis(allyloxy)benzene. The synthetic process is optimized to achieve 30 % solids content latexes with weight average molecular weight ranging from 8.2 kg/mol to 136 kg/mol. The resulting poly(thioether) latexes yield consistent continuous polymer films after water evaporation at atmospheric conditions. Poly(thioether) films based on both biobased thiol and ene are soft and sticky, and thus, present insufficient mechanical properties for coating application. On the other hand, when biobased thiol was combined with petroleum based enes with aromatic and cyclic moieties within the structure, the obtained films are rigid and film forming. Only the film based on diallyl terephthalate diene present excellent balance of stiffness and flexibility, therefore with potential for coating application. Moreover, this film shows relatively good water sensitivity, with water uptake below 20 % after 11 days of water immersion and high gloss (above 80 gloss unit) measured at 60° angle of incidence. The properties are within the range of requirements for decorative coatings applications.

Unveiling the Environmental Impacts of Concentrated Latex Manufacturing in Sri Lanka through a Life Cycle Assessment

Sri Lanka is a top producer of premium quality concentrated latex (CL), which becomes a base material for dipped rubber products such as gloves and condoms. The processing of CL is resource-intensive, requiring significant amounts of energy, fuel, water, and chemicals. This process leads to various environmental issues such as wastewater pollution, malodor, and greenhouse gas emissions. Several environmental life cycle assessments (LCA) have been conducted at international and local levels to address the aforesaid issues. However, LCAs encapsulating different environmental impact areas on CL processing in Sri Lanka are absent. The study revealed that electricity usage was the main hotspot of the environmental burden, significantly impacting abiotic depletion (fossil fuels), global warming potential, ozone layer depletion, photochemical oxidation, and acidification. Heavy reliance on coal in the Sri Lankan power grid was identified as the root of this trend. The study suggested two viable options to mitigate the environmental impact: installing inverters to centrifuge separators and solar systems in the factories. The second option was deemed more effective, reducing acidification, photochemical oxidation, and global warming potential by approximately 37%, 36%, and 28%, respectively. Relevant officials may immediately consider these improvement options and collaborate to pave the way to a sustainable natural rubber industry.

Influence of different protein contents from several clonal varieties of Hevea brasiliensis latex on the properties of cured natural rubber film using glutaraldehyde (GA) as a curing agent

Natural rubber films were prepared from four different Hevea brasiliensis clones, namely RRIM600, RRIT251, PB235, and BPM24, using the creamed concentrated latex method. The creamed latexes were characterized by their protein content and particle sizes. The rubber particle surface characteristics were monitored using transmission electron microscopy (TEM). It was observed that the particle sizes of all clones varied in the range of 1.0–2.5 µm. Moreover, the RRIT251 clone exhibited higher protein content than the other clones. The influence of protein content on the properties of cured natural rubber (NR) was investigated using glutaraldehyde as a cross-linking agent. Mechanical properties, crosslink density, relaxation behavior, and heat resistance indicated by T90 (temperature scanning stress relaxation, TSSR) were considered. The crosslink density of cured NR increased with higher protein content. This phenomenon can be attributed to the strong formation of rubber chains with GA cross-links through the amino groups of proteins present in rubber molecules. Consequently, Hevea brasiliensis clones with higher protein content facilitate improved crosslink formation within the GA system, resulting in enhanced mechanical and thermo-oxidative degradation properties (T90 from TSSR test).