Latex Research Articles

Effect of Nanodispersed Carbon Black on the Aggregative Stability of Butadiene–Styrene Latex in Liquid-Phase Filling in an Ultrasonic Field

The influence of the morphology of dispersed particles, sorption ability, and oxygen-containing groups of carbon black on the destabilization of the SKS-30ARK emulsion rubber latex in liquid-phase filling with nanodispersed carbon black in an ultrasonic field was studied. The latex destabilization is caused by sorption of emulsifying agents onto carbon black from the protective surface of latex globules, which is indirectly confirmed by an increase in the surface tension coefficient of the latex system. The complete coagulation of the butadiene–styrene latex is reached without using coagulants in the course of liquid-phase filling with carbon black at the component ratio carbon black : rubber 100 : 100 (wt parts) and рН ≤ 4.3 when using K354 carbon black and at the same component ratio and рН ≤ 3.6 when using P324 carbon black. Liquid-phase filling of emulsion rubbers in the step of their recovery from the latex ensures uniform distribution of nanodispersed carbon black throughout the volume of the elastomer compound due to the dispersing effect of the emulsifying components of the latex. These components migrate from the surface of latex globules to the developed active surface of carbon black under the action of ultrasonic field.

Amphotericin B-loaded natural latex dressing for treating Candida albicans wound infections using Galleria mellonella model

Amphotericin B (AmB) is the gold standard for antifungal drugs. However, AmB systemic administration is restricted because of its side effects. Here, we report AmB loaded in natural rubber latex (NRL), a sustained delivery system with low toxicity, which stimulates angiogenesis, cell adhesion and accelerates wound healing. Physicochemical characterizations showed that AmB did not bind chemically to the polymeric matrix. Electronic and topographical images showed small crystalline aggregates from AmB crystals on the polymer surface. About 56.6% of AmB was released by the NRL in 120 h. However, 33.6% of this antifungal was delivered in the first 24 h due to the presence of AmB on the polymer surface. The biomaterial's excellent hemo- and cytocompatibility with erythrocytes and human dermal fibroblasts (HDF) confirmed its safety for dermal wound application. Antifungal assay against Candida albicans showed that AmB-NRL presented a dose-dependent behavior with an inhibition halo of 30.0 ± 1.0 mm. Galleria mellonella was employed as an in vivo model for C. albicans infection. Survival rates of 60% were observed following the injection of AmB (0.5 mg.mL−1) in G. mellonella larvae infected by C. albicans. Likewise, AmB-NRL (0.5 mg.mL−1) presented survival rates of 40%, inferring antifungal activity against fungus. Thus, NRL adequately acts as an AmB-sustained release matrix, which is an exciting approach, since this antifungal is toxic at high concentrations. Our findings suggest that AmB-NRL is an efficient, safe, and reasonably priced ($0.15) dressing for the treatment of cutaneous fungal infections.

Enhancing Water Resistance in Cationic Cellulose Nanofibril Adhesive with Natural Rubber Latex

Enhancing Water Resistance in Cationic Cellulose Nanofibril Adhesive with Natural Rubber Latex

Research on the effects of jute fibers filler content and surface treatment on the mechanical properties of natural rubber latex foam

AbstractNatural rubber latex foam (NRLF) filled with untreated and alkali/silane coupling agent‐treated jute fibers (JFs) were prepared using the Dunlop method. The JFs fillers were added at 0, 1, 3, and 5 phr. The density, crosslinking degree, and surface morphology of the untreated jute‐filled NRLF were studied, and the tensile and compression properties of the untreated and surface‐treated NRLF were compared. The results showed that the density, the modulus at 100% elongation (M100), and compression set of the untreated jute‐filled NRLF increased with increasing JFs filler content. The crosslinking degree, tensile strength, elongation at break, and recovery rate decreased with increasing JFs filler content. Regarding mechanical properties, the surface‐treated JFs‐filled NRLF exhibited higher tensile strength and M100 than the untreated group, indicating that alkali/silane coupling agent treatment enhanced the interaction between JFs and the matrix. However, the elongation at break was lower. As for the compression set and recovery rate, there was no significant difference between the two groups, indicating that alkali/silane coupling agent treatment had little effect on the compression set and recovery rate of JFs‐filled NRLF.

The Interplay of Protein Hydrolysis and Ammonia in the Stability of Hevea Rubber Latex during Storage.

Natural rubber (NR) latex derived from Hevea brasiliensis is a complex colloid comprising mainly rubber hydrocarbons (latex particles) and a multitude of minor non-rubber constituents such as non-rubber particles, proteins, lipids, carbohydrates, and soluble organic and inorganic substances. NR latex is susceptible to enzymatic attack after it leaves the trees. It is usually preserved with ammonia and, to a lesser extent, with other preservatives to enhance its colloidal stability during storage. Despite numerous studies in the literature on the influence of rubber proteins on NR latex stability, issues regarding the effect of protein hydrolysis in the presence of ammonia on latex stability during storage are still far from resolved. The present work aims to elucidate the interplay between protein hydrolysis and ammoniation in NR latex stability. Both high- and low-ammonia (with a secondary preservative) NR latexes were used to monitor the changes in their protein compositions during storage. High-ammonia (FNR-A) latex preserved with 0.6% (v/v) ammonia, a low 0.1% ammonia/TMTD/ZnO (FNR-TZ) latex, and a deproteinized NR (PDNR) latex were labeled with fluorescence agents and observed using confocal laser scanning microscopy to determine their protein composition. Protein hydrolysis was confirmed via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results revealed that protein hydrolysis increased with the storage duration. The change in protein composition accompanying hydrolysis also allows the spatial distribution of allergenic proteins to be estimated in the latex. Concurrently, the latex stability increased with the storage duration, as measured by the latex's mechanical stability time (MST) and the zeta potential of the latex particles. As monitored by AFM, the surface roughness of the NR latex film increased markedly during extended storage compared with that of the DPNR latex, which remained smooth. These results underscore the pivotal role of ammonia in bolstering NR latex stability brought on by protein hydrolysis, which greatly impacts latex film's formation behavior. NR latex stability underpins the quality of latex-dipped goods during manufacturing, particularly those for medical gloves.

Natural Rubber Latex on Medical Applications

In this review, latex from the Hevea Brasiliensis tree is presented as a material originating from nature, used to produce natural rubber, raw material for countless products for industry, as well as the manufacture of preservatives, and gloves, among others. Nowadays, its potential is expanding into various technological areas, one of which is biomedical, as described in this article. Latex has the possibility of being preserved using ammonium, which is a chemical of high health risk, but nowadays it is being substituted by acid systems excluding traditional chemicals. With these new preservation processes, the prospective use of latex for the design of biosensor scaffolds for drug release, and as membranes that can replace synthetic latex in patches for bioremediation in soft and bone tissues, synthetic muscles, membranes for biological micro laboratories, among others, is being studied to optimize its possibilities.

Design and development of latex cup collector robot

Global rubber production has declined over the past few years as a result of a number of variables, including both environmental and human factors. In this paper, an automated robot prototype that collects latex cups was developed to improve global rubber production by assisting workers in rubber plantations. The robot was built on a mobile platform with a motorized Five Degrees of Freedom (DoF) robotic arm, Ackermann steering, double wishbone suspension, rear-wheel drive and a latex storage tank to store the latex collected from the trees. The robot was equipped with ultrasonic sensors and a camera module to locate latex cups and rubber trees so that it could move and perform tasks accurately. In addition, encoder sensor modules were used to improve the accuracy of the movements by measuring the rotational speed of the motors. The yield strength of the PLA plastic material used in developing the latex cup collector robot is 7.00 x 107N/m2 and the maximum stress of the critical parts should not exceed the maximum yield strength of the PLA plastic. In mobility test, the robot is able to travel through obstacles of 10mm and 15mm height. The topple angle of the robot in the balancing test is greater than 37°, ensuring the stability of the robot.

Аллергия на латекс

Latex, made from Hevea brasiliensis sap, is the material used to make many medical products, including catheters, balloons and gloves. Hundreds of allergens from natural rubber latex have been identified, and 15 of them were numbered, from Hev b1 to Hev b15. Natural proteins in rubber cause both asymptomatic sensitization and type I IgE-mediated hypersensitivity. Treatment of latex makes use of chemical antioxidants that can also bring about type IV hypersensitivity reactions. Latex allergy is one of the most common causes of anaphylaxis in the operating room, and its prevalence has been growing since 1980s, together with the popularity of latex gloves. It is a well-known problem among medical professionals, with gloves and inhaled aerosol particles being the sources thereof. This study aimed to review the current scientific research and practical data in this only partially investigated area. In addition, increasing the awareness of doctors and patients minimizes the existing risks of latex allergy.

A New Preparation Method for cis-1,4-polyisoprene/Na-montmorillonite Latex Composites by in situ Solution Emulsification

AbstractCis-1,4-polyisoprene latex (IRL) is the best alternative to natural rubber latex (NRL), and can help to avoid human allergic reactions caused by proteins in NRL. The mechanical properties of IRL are inferior to those of NRL, however. To address this issue, a novel strategy was developed using an in situ solution emulsification to prepare a latex composite incorporating sodium montmorillonite (Na-Mnt). The properties of the latex film prepared were investigated. The dispersion state of the Mnt in the latex composites and the morphology of the resulting composite films were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, the mechanism of Mnt reinforcement of IRL is described comprehensively. The results showed that the Mnt/IRL latex composites prepared were stable and excellent films were formed, similar to those of NRL. The current research provided an effective method for preparing high-performance composite films suitable for use in high-end medical applications.

Influence of a dialysed polymer latex on the hydration of OPC – A closer look into adsorption processes

The impact of a dialysed styrene acrylate copolymer on cement hydration was investigated. The retarding and depressing mechanism of the polymer particles on OPC hydration was examined via heat flow calorimetry, in-situ X-ray analysis and pore solution composition measurements. To ensure excessive polymer particles were remaining in the pore solution during the hydration, a high polymer-cement-ratio was chosen. It is found that the physical mechanism, the adsorption, is the most influential cause of the retardation and depression. Both aluminate and silicate reactions are strongly inhibited by the adsorption of polymer particles on hydrate phases. As long as polymer particles are found in the pore solution, newly forming surfaces are directly occupied by the latex particles, thus delaying the reaction. The OPC hydration is kinetically slowed down by polymer particle adsorption even though thermodynamically there is no hindrance for the hydration progression.

Surface energy considerations for offset printing of coated paper and paperboard

Offset printing of coated paper involves the complex interactions of ink with a surface that is characterized by three major properties: roughness, porosity, and related pore network structure and surface chemistry (related to surface free energy [SFE]). The effects of porosity and roughness are relatively well understood and are documented in the literature, whereas the influence of surface chemistry is much less studied and therefore the focus of this paper. The key results shown include: i) Coating porosity has a negligible effect on SFE determination by contact angle using two fluids. ii) The chemistry of the latex polymer in the coating formulation dominates the influence on SFE compared to pigment, with any surface energy differences present in the pigment being almost completely masked by latex. iii) Wetting agent and corona treatment can impact water absorption rate and surface spreading of water, resulting in small differences in printability. Increasing the concentration of the surfactant on a coated surface indicates switching orientation of the surfactant molecules, giving a “step wise” printing result. When looking to improve offset printability by selection of different pigments, the variation in SFE is less important than variation in either surface roughness or porosity.

Photopolymerization Inks for 3D Printing of Elastic, Strong, and Biodegradable Oral Delivery Devices

AbstractThree‐dimensional (3D) printing via vat photopolymerization is transforming the manufacturing paradigms of biomedical devices, offering tremendous advantages for the production of customized advanced drug delivery systems. However, the existing commercial inks often lack the ability to simultaneously provide elasticity, strength, and biodegradability. Herein, photopolymerizable inks based on poly(β‐aminoester) diacrylates and N‐vinyl pyrrolidone are used to address these limitations. These biodegradable polymers enable the digital light processing 3D printing of elastomers with adjustable elongation at break (103–762%), stress at failure (0.2–8.3 MPa), and hydrolysis rates ranging from 25 min to 80 days. The authors are able to synthesize a soft polymer that possess properties akin to natural latex, which can enhance its elastic modulus when subjected to high strains. It can withstand 762% stretch with a maximum strength of 8.3 MPa. In addition, this polymer demonstrates cytocompatibility and unique biodegradation properties under simulated gastrointestinal conditions (within hours at pH 6.8). By utilizing this elastomer, a prototype of an expandable oral drug delivery device that has the ability to degrade within the average transit time in the jejunum is manufactured. This study paves the way to leverage vat photopolymerization 3D printing in the creation of complex prototypes of biomedical devices where strength, elasticity and biodegradability are essential.

Integrated approaches to prevent exposure risks related to latex-derived products

Natural rubber latex is a widely used industrial raw material to produce many consumer and commercial products. Chronic exposures to latex allergenic proteins residual in the finished products can promote hypersensitive immune responses, which affects millions of workers and the general public worldwide. Research has shown the average prevalence of latex allergy worldwide remains approximately 10% among healthcare workers, 7% among susceptible patients, and 4% among general population. Although most effective in preventing latex allergy, completely avoiding contact to latex-derived products is extremely challenging, given the fact that millions of products possibly contain latex, but few are regulated and properly labeled. Due to the difficulty to assure a product completely absent of latex allergens, the United States Food and Drug Administration has recommended to stop using labels like “latex-free” or “does not contain latex.” Here we evaluate published data, industrial standards and regulations, identify possible countermeasures, and propose an integrated strategy, including some more practicable approaches (e.g., education/training, product labeling, the use of proper personal protective equipment, occupational selection, and searchable product database) and novel medical treatments (e.g., immunotherapy) to help decreasing latex allergy prevalence.

Evaluation of an ammonia‐free natural rubber latex adhesive

AbstractNatural rubber latex (NRL) within the adhesives industry has had limited applications because of poor water and chemical resistance; additionally, conventional preservation methods with ammonia produce poor adhesive properties and introduce toxicity. Today, solvent‐based adhesives dominate the market because of their superior mechanical properties; however, they negatively affect the health of users depending on the application due to the toxic chemicals. In this study, we investigated using a novel NRL‐based ammonia‐free adhesive as primary materials with bio‐additives, specifically cellulose, and collagen, to enhance their mechanical property provide the industry with an adhesive safe to handle. The peeling strength of an ammonia‐free NRL, 60% dry rubber content (DRC) NRL, with cellulose and collagen (Industrial Adhesive) were compared to high‐performance adhesives used within the footwear and construction industry to prove these adhesives direct applicability within these industries. Our findings showed that the ammonia‐free NRL Industrial Adhesive exhibited superior mechanical properties when compared against resilient flooring adhesives and footwear adhesives. Additionally, the peeling strength of an ammonia‐free 35% DRC with only cellulose (Office Adhesive) was compared to PVA‐based Elmer's Glue and it was observed that the ammonia‐free NRL adhesive outperformed Elmer's Glue by almost reaching four times the peeling strength of Elmer's Glue.

The polymer interdiffusion in disulfide dynamic crosslinked latex films

Embedded dynamic covalent bonds can endow polymers with special interfacial properties and interdiffusion behaviours. Such benefits from dynamic covalent bonds are particularly significant in polymer latices because their filming is based on joining surfaces and polymer interdiffusion. We prepared films from disulfide dynamically crosslinked, permanently crosslinked and noncrosslinked latices, and the polymer interdiffusion in the annealed films was monitored by a vibrationally resolved pyrene-based fluorescence probe. The fluorescence signals were converted into parameters of polymer interdiffusion, including fracture of mixing (fm), diffusion coefficient (D) and apparent activation energy (E). By comparing the diffusion parameters and the mechanical properties of the disulfide crosslinked latex with the permanent crosslinked and noncrosslinked latex, it is concluded that only 2 mol% of disulfide crosslinkers would make the latex significantly distinctive, especially at temperatures higher than 90 °C where disulfide exchange was activated.

Cushion performance of eco-friendly natural rubber latex foam composite with bamboo leaf fiber for impact protection of guava

This study investigated the performance of an eco-friendly cushion foam net comprised of natural rubber latex and bamboo leaf fiber. It compared this innovative BambooLatex foam net (thickness of 2.52 and 3.57 mm) with a commercial expanded polyethylene foam net (EPE) (thickness of 5.85 and 7.30 mm) as well as a control group with no cushioning. Key cushioning properties including thickness, mass, modulus, compressive strength, damping coefficient, and energy absorption were investigated. To assess cushion performance was conducted a simulated impact test involving guavas dropped from varying heights (200, 300 and 400 mm). The impacted fruits were subsequently stored at 20 ºC and 75% relative humidity for 4 days. During this period, we monitored bruising development using an image analysis technique, evaluating bruise area, fractal dimension, and grayscale as fruit quality parameters. Our findings indicated that thicker cushions offered superior protection, exemplified by the 7.30 mm EPE. However, the cushion material's damping coefficient and energy absorption capacity significantly influenced its ability to reduce impact energy. This resulted in the thinner BambooLatex foam net performing comparably to the EPE foam net. All cushion treatments significantly reduced impact bruising of guava fruit to less than 2% of the bruise area) as compared to the control (4–7% of the bruise area). There was no significant difference in fractal dimension and grayscale values among the four cushioning treatments. The bruise area parameter was recommended as it gave a better resolution for classifying impact fruit bruising severity in the cushion study. Ongoing developments are aimed at further reducing the weight of the eco-friendly natural rubber latex cushion and incorporating additional active functions.

Stiffness, rutting, and fatigue performance evaluation of cement-natural rubber latex stabilized recycled concrete aggregate

ABSTRACT The stiffness, rutting, and fatigue performance of cement-natural rubber latex (NRL) stabilized recycled concrete aggregate (RCA) were evaluated under cyclic loading. The RCA was stabilized with 3% cement content and dry rubber content to cement (r/c) ratios at 5%, 10% and 15%. The performance evaluation was carried out through advanced experiments, including indirect tensile resilient modulus test, indirect tensile fatigue test, and rutting susceptibility test using a Hamburg wheel tracking device. The results indicated that the r/c ratio of 10% was optimum for cement-NRL stabilized RCA (3C10R-RCA), which exhibited the optimum performance in terms of permanent deformation, fatigue cracking, and rutting susceptibility. The indirect tensile fatigue life of 3C10R-RCA was found to be 79.3% greater than that of the 3% cement stabilized RCA (3C-RCA), while the rut depth of 3C10R-RCA was 8% lower. Although the resilient modulus value of 3C10R-RCA was slightly lower than that of 3C-RCA, the tensile permanent deformation was found to be lower, which is associated with the lower rut depth. As a result of the significant improvement in fatigue life and rutting performance, the resistance to fatigue cracking and premature failure of cement-NRL stabilized RCA were improved.

EFFECTS OF MANAGEMENT PRACTICES AND TAPPING SYSTEM ON LATEX AND DRY RUBBER YIELDS OF RUBBER TREE CLONE RRIT 251

The cultivation of Hevea brasiliensis, as the main source of natural rubber, is facing the tapping labor shortage and low dry rubber yield problems. Management practices and tapping system could nevertheless remedy these constraints. Accordingly, the study aimed to assess the latex and dry rubber yields of rubber trees clone RRIT 251 under different irrigation with fertilizer management methods and rubber tapping systems. The experiment was laid out in a split-plot design, 4 replications with 3 rubber trees per replication. Two main plot treatments: 1) application of irrigation combined with chemical and organic fertilizers treatment (IF) and; 2)no-irrigation-fertilizer treatment (NIF). Four subplot treatments: 1) (10 cm)S.d/3+ET – tapping 10 cm long of trunk girth (at 45° angle) above an installed bag of ethylene, for 1 day with 2 days interval; 2) (1/2)S.d/2 – tapping half of trunk girth every other day; 3) (1/2)S.2d/3, tapping half of trunk girth for 2 days with 1 day interval (the practice of most para rubber farmers) and; 4) (1/2)S.3d/4, tapping half of trunk girth for 3 days with 1 day interval. The controlled treatment was a combination treatment of NIFx (1/2)S.2d/3. The results showed that both IFx (10 cm)S.d/3+ET and IFx (10 cm)S.d/3+ET combination treatments had significant effects (P≤0.01) in enhancing latex weight per tree, dry rubber weight per tree, latex yield, and dry rubber yield higher than the controlled treatment. IF treatment had a significant effect (P≤0.01) in enhancing latex weight per tree, dry rubber weight per tree, latex yield, and dry rubber yields higher than NIF treatment. Rubber tapping system under (1/2)S.3d/4 had a significant effect (P≤0.01) in enhancing latex weight per tree, dry rubber weight per tree, latex yield, and dry rubber yield while it was significantly (P≤0.01) low under (1/2)S.d/2 as compared with the practice used of most farmers—(1/2)S.2d/3. It is concluded that the application of ethylene under IFx (10 cm)S.d/3+ET management is a better innovation and technology attributable to having 45% less time and less bark area consumed for tapping but with increased dry rubber yield, while IFx (1/2)S.2d/3 spent more time to increase the dry rubber yield, as compared with the controlled treatment. Keywords: Ethylene, Fertilizer, Irrigation, Latex, Rubber

Around the Wire: Telegraphic Infrastructure and Gothic Energies in Late Victorian Britain

This article explores a link between gutta-percha, the natural South-East Asian latex used nearly exclusively as an insulation for nineteenth-century British telegraph cables, and the development of electromagnetic field theory. Field theory emerged from the non-traditional methods of physicist Michael Faraday, who demonstrated that the energy in telegraph cables is located around, rather than within, the conducting wire. Eventually, the application of field theory in telegraphy required the knowledge and resources of Indigenous forest produce collectors, as well as contingent networks of Chinese and Malay traders linked into local and global supply chains. Telegraphic infrastructure, therefore, is not simply the cables and signalling systems developed by the British, but also the knowledge, resources, and cultures of South-East Asian Indigenous communities and lifeways that resisted the Western energy project ‘around’ the conducting wire. Britain’s global telegraphy enterprise relied on enormous quantities of gutta-percha, procured only by Indigenous collectors whose methods refused settler colonial agricultural practices like the plantation model. Based on the widespread demand for, and increasing shortage of, gutta-percha by the late nineteenth century, this article argues that Stoker’s Dracula characterizes the Count using language that overlaps with the ambient, uncategorizable energy of field theory, as well as non-Western practices crucial to the gutta-percha supply chain, like animal augury.

Durability against Wetting and Drying Cycles and Installation Damage of Water Hyacinth Geotextiles Coated with Natural Rubber Latex

Durability against Wetting and Drying Cycles and Installation Damage of Water Hyacinth Geotextiles Coated with Natural Rubber Latex