Natural Rubber Gloves Research Articles

Metathetic degradation of waste natural rubbers for potential reutilization

Waste rubbers have caused a severe environmental pollution now. Their reutilization is an urgent eco-economic demand for the sustainable society by converting the wastes into feedstock for the chemical industry. In the present work, the metathetic degradation of waste rubbers (waste natural rubber gloves as model) was comprehensively investigated with different chain transfer agents (CTAs). The waste natural rubber gloves could be degraded with three CTAs with different polarities (styrene, methyl acrylate (MA) and acrylic acid (AA)), catalyzing with the HG2 catalyst in chloroform. Four kinds of main reactions were proposed in the olefin cross-metathesis (OCM) degradation, based on the product analysis. It was also found that the degradation was favored by a consistent low concentration of the CTA, inhibiting the by-reactions and subsequently improving the degradation yield. Therefore, an easy and effective strategy for the high-performance OCM degradation of waste rubbers was proposed by dropping the CTA.

Biological Degradation of Natural Rubber Glove by Gram-negative Bacteria Klebsiella aerogenes

Biological Degradation of Natural Rubber Glove by Gram-negative Bacteria Klebsiella aerogenes

Investigation of potential rubber-degrading bacteria and genes involved.

COVID-19 pandemic has generated high demand for natural rubber gloves (NR) leading to crucial issues of rubber waste and waste management such as burning, dumping, stockpiling, discarding waste in landfills. Hence, rubber biodegradation by microorganisms is an alternative solution to the problem. The biodegradation method is environmentally friendly but normally extremely slow. Numerous microorganisms can degrade NR as a source of carbon and energy. In this study, Rhodococcus pyridinivorans KU1 was isolated from the consortium CK from previous study. The 40% rubber weight loss was detected after incubated for 2months. The bacterial colonization and cavities on the surface of rubber were identified using a scanning electron microscope (SEM). The result demonstrated the critical degradation of the rubber surface, indicating that bacteria can degrade rubber and use it as their sole carbon source. The result of whole-genome sequencing (WGS) revealed a gene that is 99.9% identical to lcp which is responsible for poly (cis-1,4-isoprene) degradation. The results from Meta16S rRNA sequencing showed that the microbial communities were slightly shifted during the 2-month degradation, depending on the presence of monomers or oligomers appeared during the degradation process. The majority of species were soil bacteria such as phylum Proteobacteria, Actinobacteria, and Firmicutes. Members of Pseudoxanthomonas seemed to be the dominant degraders throughout the degradation.

Performance-Enhancing Materials in Medical Gloves.

Medical gloves, along with masks and gowns, serve as the initial line of defense against potentially infectious microorganisms and hazardous substances in the health sector. During the COVID-19 pandemic, medical gloves played a significant role, as they were widely utilized throughout society in daily activities as a preventive measure. These products demonstrated their value as important personal protection equipment (PPE) and reaffirmed their relevance as infection prevention tools. This review describes the evolution of medical gloves since the discovery of vulcanization by Charles Goodyear in 1839, which fostered the development of this industry. Regarding the current market, a comparison of the main properties, benefits, and drawbacks of the most widespread types of sanitary gloves is presented. The most common gloves are produced from natural rubber (NR), polyisoprene (IR), acrylonitrile butadiene rubber (NBR), polychloroprene (CR), polyethylene (PE), and poly(vinyl chloride) (PVC). Furthermore, the environmental impacts of the conventional natural rubber glove manufacturing process and mitigation strategies, such as bioremediation and rubber recycling, are addressed. In order to create new medical gloves with improved properties, several biopolymers (e.g., poly(vinyl alcohol) and starch) and additives such as biodegradable fillers (e.g., cellulose and chitin), reinforcing fillers (e.g., silica and cellulose nanocrystals), and antimicrobial agents (e.g., biguanides and quaternary ammonium salts) have been evaluated. This paper covers these performance-enhancing materials and describes different innovative prototypes of gloves and coatings designed with them.

Toxicity reduction of natural rubber gloves using protein crosslinking technique

AbstractFor natural rubber (NR) gloves, residual latex processing chemicals are the important substances that cause adverse reactions to users who are sensitive to them. Many attempts have therefore been made to reduce or eliminate these leachable chemicals from the gloves such as natural compound addition and polymer coating. The current study proposed a novel alternative method to reduce chemical allergens from NR gloves by protein crosslinking through the Maillard reaction that is possible to adapt to the existing glove production. Commercial NR gloves were initially treated with various concentrations of glutaraldehyde, a crosslinking agent, ranging from 0.00% to 1.00%w/w prior to being tested for cytotoxicity, contact angle, water absorption, and mechanical properties. Artificial sweat and culture medium with serum (complete medium) were used as vehicles for in vitro cytotoxicity tests. Results from the test revealed that, regardless of the vehicle type, increasing glutaraldehyde concentration reduced the toxicity of NR gloves, indicating the reduction of leachable toxic substances after the treatment. Contact angle and water absorption resistance were found to increase with increasing glutaraldehyde concentration, reflecting the enhanced hydrophobicity of the treatment. The mechanical properties of the gloves were not significantly different after such treatment. The results confirm the potential use of this protein crosslinking method to reduce the allergy problem of NR gloves.

Effect of Latex Purification and Accelerator Types on Rubber Allergens Prevalent in Sulphur Prevulcanized Natural Rubber Latex: Potential Application for Allergy-Free Natural Rubber Gloves.

Natural rubber (NR) gloves manufactured from NR latex are widely utilized in various applications as a personal protective device due to their exceptional barrier characteristics in infection control. However, the use of NR gloves was associated with concerns on NR protein allergy. With comprehensive leaching procedures now a common practice in NR latex glove factories to eliminate latent rubber proteins and chemical allergens, occurrences and complaints of protein allergy from medical glove users have decreased drastically over the past two decades. The present work aims to eliminate further the residual rubber allergens in NR latex through effective purification of the NR latex and compounding the thus purified latex with an established formulation for allergy-free NR for glove applications. NR latex was purified by deproteinization and saponification, respectively. Several analytical techniques were used to verify rubber allergens eliminated in the purified latexes. Saponified NR (SPNR) latex was the purified NR latex of choice since it is devoid of allergenic proteins and poses the lowest risk of Type I allergy. The purified NR latex was compounded with zinc diethyldithiocarbamate (ZDEC), zinc dibutyldithiocarbamate (ZDBC), and zinc 2-mercaptobenzothiazole (ZMBT), respectively, for glove dipping. Among the investigated accelerators, only ZDBC was not detected in the artificial sweat that came into contact with the dipped articles. Thus, it is deduced that ZDBC poses the lowest risk of Type IV allergy to consumers. Additionally, the morphological and physical properties of dipped articles were assessed. It was revealed that the dipped film from the SPNR latex compounded with ZDBC provided thinner and less yellow products with a more uniform internal structure and a tensile strength comparable to those of commercial NR gloves.

Catalytic cascade upcycling single-use natural rubber glove wastes into fuels via a two-stage pressurized fixed-bed reactor

Chemical upcycling rubber wastes into hydrocarbon fuels offers a promising approach toward achieving carbon neutrality. To generate fuel-range cycloalkanes and isoalkanes from natural rubber glove wastes (NRGWs), the depolymerization of NRGWs was performed by integrating hydropyrolysis with vapor-phase hydrogenation over a bifunctional Ni/Al2O3-SiO2 catalyst. Isoprene and limonene were the primary alkenes obtained from the non-catalytic hydropyrolysis of NRGWs, and these intermediates were vapor-phase hydrotreated over Ni/Al2O3-SiO2 producing C10 cycloalkane as the dominant fuel-range products. Complete hydrogenation of isoprene and limonene was achieved under a catalyst to feedstock mass ratio of 2.0, giving a maximum gasoline yield of 92 wt% under 225 °C hydrogenation temperature at 0.2 MPa H2. A low hydropyrolysis temperature of 450 °C maximized C10 cycloalkane yield at 72.3 wt% with 80.1% selectivity, while a high temperature of 600 °C yielded 76.6 wt% C5 isoalkane. A deconstruction mechanism in the catalytic cascade upcycling of NRGWs was proposed by employing limonene hydrogenation as a probe reaction. The results demonstrate that upcycling polymer wastes by cascade hydropyrolysis‑hydrogenation is a promising approach to produce alternative fuels with improved properties.

Wearable Natural Rubber Latex Gloves with Curcumin for Torn Glove Detection in Clinical Settings.

Glove tear or perforation is a common occurrence during various activities that require gloves to be worn, posing a significant risk to the wearer and possibly others. This is vitally important in a clinical environment and particularly during surgical procedures. When a glove perforation occurs (and is noticed), the glove must be replaced as soon as possible; however, it is not always noticeable. The present article is focused on the design and development of a novel fluorescence-based sensing mechanism, which is integrated within the glove topology, to help alert the wearer of a perforation in situ. We hypothesized that natural rubber gloves with curcumin infused would yield fluorescence when the glove is damaged, particularly when torn or punctured. The glove design is based on double-dipping between Natural Rubber Latex (NRL) and an inner layer of latex mixed with curcumin, which results in a notable bright yellow-green emission when exposed to UV light. Curcumin (Cur) is a phenolic chemical found primarily in turmeric that fluoresces yellowish-green at 525 nm. The tear region on the glove will glow, indicating the presence of a Cur coating/dipping layer beneath. NRL film is modified by dipping it in a Cur dispersion solution mixed with NRL for the second dipping layer. Using Cur as a filler in NRL also has the distinct advantage of allowing the glove to be made stronger by evenly distributing it throughout the rubber phase. Herein, the optimized design is fully characterized, including physicochemical (fluorescence emission) and mechanical (tensile and tear tests) properties, highlighting the clear potential of this novel and low-cost approach for in situ torn glove detection.

Waste NR Latex Based-Precursors as Carbon Source for CNTs Eco-Fabrications.

In this work, the potential of utilizing a waste latex-based precursor (i.e., natural rubber glove (NRG)) as a carbon source for carbon nanotube (CNT) fabrication via chemical vapor deposition has been demonstrated. Gas chromatography-mass spectroscopy (GC-MS) analysis reveals that the separation of the lightweight hydrocarbon chain from the heavier long chain differs in hydrocarbon contents in the NRG fraction (NRG-L). Both solid NRG (NRG-S) and NRG-L samples contain >63% carbon, <0.6% sulfur and <0.08% nitrogen content, respectively, as per carbon-nitrogen-sulfur (CNS) analysis. Growth of CNTs on the samples was confirmed by Raman spectra, SEM and TEM images, whereby it was shown that NRG-S is better than NRG-L in terms of synthesized CNTs yield percentage with similar quality. The optimum vaporization and reaction temperatures were 350 and 800 °C, respectively, considering the balance of good yield percentage (26.7%) and quality of CNTs (ID/IG = 0.84 ± 0.08, diameter ≈ 122 nm) produced. Thus, utilization of waste NRG as a candidate for carbon feedstock to produce value-added CNTs products could be a significant approach for eco-technology.

A Natural Rubber Waste Derived Surfactant for High Internal Phase Emulsion Templating of Poly(Dicyclopentadiene)

AbstractThe use of a surfactant derived from the degradation of natural rubber gloves via cross‐metathesis with methyl acrylate and subsequent saponification of the ester group for the stabilization of water in dicyclopentadiene high internal phase emulsions is described. The versatility of the resulting high internal phase emulsion is demonstrated by polymerizing the continuous dicyclopentadiene phase via ring‐opening metathesis polymerization yielding macroporous poly(dicyclopentadiene) foams with a porosity of 82%. The use of the ionic surfactant allows for the preparation of foams, which are resistant to absorb water. This property is hitherto not accessible with protocols involving the use of nonionic surfactants commonly employed in emulsion templating of polymers.

Modified natural rubber glove with spent coffee grounds for prothesis arm cover

In this research, we developed modified rubber gloves that could cover prosthetic arms manufactured from Fused Deposition Modeling (FDM) 3D printing. FDM can produce customized prosthetic arms that are lightweight and fit the individual needs of patients. Currently, the gloves used to cover prosthetic arms are made from flexible and soft material such as silicone or polyurethane. In these studies, were use natural rubber latex (NR) to produce rubber gloves, that enhance the physical appearance of the prosthetic arm, producing a similar color and detail to the patients arm. The glove color was improved by mixing with spent coffee grounds (SCG) to produce a similar color to that of natural human skin. Moreover, SCG was not only used as a color pigment, it also contains coffee oil that creates a glossy textured on the surface similar to silicone oil. The modification process of NR used a SCG dispersion solution mixed with NR. Rubber gloves were prepared by a dipping process and use sulfur vulcanization at 75 °C, for 2 h in a hot air oven. The specimens were characterization by physical (morphology, color parameter, and %swelling), mechanical (tensile test) and thermal properties. Furthermore, the SCG can be used as a filler in natural rubber due to rubber-filler interactions that improve the tensile strength of the rubber glove with the SCG particles having a good distribution in the rubber phase. The SCG can improve the ageing stability (under 70 °C and Fluorescent light) of the rubber gloves as represented by the color parameter and tensile properties. After ageing showed a small difference in color parameter and a slight decrease in the tensile properties when greater amounts of SCG was presented in the rubber phase. Moreover, this can increase the economic value of natural rubber and spent coffee grounds in Thailand.

Effect of Reaction Temperature on the Growth of Carbon Nanotubes from Waste Natural Rubber Glove

Natural rubber (NR) glove disposal is not environmentally appropriate and a range of approaches have been suggested to overcome the problem. Herein we indicate a simple method for producing high-value nanotubes from waste NR glove as a partial solution to the environmental problem. The laboratory-based waste NR glove was selected as a carbon precursor. Carbon nanotubes (CNTs) were synthesized using chemical vapor deposition (CVD) method comprising ferrocene over SiO2 substrate, which acted as a catalyst and surface for the carbon conversion process. The growth temperature was varied using 500, 600 and 700°C. The carbon precursor was analyzed using thermogravimetric analysis (TGA) to determine the optimum thermal decomposition of the waste. The CNTs collected after CVD process were analyzed using Raman spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM). Optimization studies to determine the effect of temperature showed that the highest yield of CNTs was produced under a reaction temperature of 700°C (yield % = 5.47%, Raman ID/IG ratio = 0.82). The nanomaterials formed confirmed as CNTs and amorphous carbon under TEM images of the tubular structure of the products with a diameter range of 13 – 16 nm.

Effects of Waveguide Position on Electric Field and Temperature Profile in Natural Rubber Gloves during Vulcanization Process Using Microwave Energy

Natural rubber gloves (NRG) become a broader industry with fierce competition and demands. The vulcanization process is the most important and takes the longest time in the cycle period of the NRG manufacturing process, so it becomes of paramount importance to improve this process. The purpose of this research is to experimentally and computationally study the characteristics of the electric field as well as temperature profile in NRG during the microwave vulcanization process. The effects of position of waveguide placement are investigated for nine different positions. The experiment of NRG microwave vulcanization is performed for temperature distribution measurement. Three-dimensional models of NRG and microwave oven are considered. Finite element method (FEM) is utilized to solve a mathematic model of the transient Maxwell’s equation coupled with the transient heat transfer equation in order to determine the electric field and temperature profile via computer simulation. The computer simulation results are validated against the experimental results. The validation confirms that the computational model is able to represent the practical transport phenomena in NRG with high accuracy. The outcomes clearly reveal that the position of waveguide effects on the electric field as well as temperature profile in NRG during the microwave vulcanization process. The positioning of waveguides on both the front and backsides on the opposite side of the microwave oven provides higher intensity electric field and higher temperature profile than the positioning of waveguides in the middle of both the front and the backsides of the microwave oven. In addition, the middle backside is the appropriate position for waveguide in which NRG is uniformly dry and not burnt or overheated. However, it is found that there is no direct relationship between the electric field and temperature changes. This research guides to essential aspects of the design of NRG vulcanization to improve the efficiency of microwave and heat delivering along with other heating systems to heat any sorts of material.

Studies on the effect of purified natural rubber latex and accelerators on rubber allergens in natural rubber dipping product

Natural rubber (NR) glove is a worldwide use product of NR latex, which is mainly used for protective purposes. However, allergic reactions to NR gloves causing by the residual proteins in NR latex and chemical used in the manufacturing process, which are called as rubber allergens, are still a significant concern. Thus, the present work is an attempt to minimize such the rubber allergens from NR dipping products, herewith, finger cot is used as a model for this study. Purified NR latices were prepared by an urea treatment and saponification method, called as deproteinized NR (DPNR) and saponified NR (SPNR), respectively. Both of DPNR and SPNR were found to have low nitrogen content. Fourier-transform infrared spectroscopy (FTIR) was used to identify functional groups as a result of the absence of the amine functional group, which can be referred to proteins. For a compounded NR, the various purified NR latices and rubber accelerators were used in the compounded formula. The existing and residual proteins of each sample were analysed by Bradford’s assay and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) method, respectively. The DPNR and SPNR were found to contain lower protein profiles. The residual rubber accelerators released into artificial sweat were extracted and analysed by high-performance liquid chromatography (HPLC) technique.

Deproteinized natural rubber film reinforced with silane-modified silica nanoparticles

Mechanical properties and morphology of the deproteinized natural rubber (NR) films reinforced with modified silica (SiO2) nanoparticles were studied in this research. In the step of deproteinization, a chemical method followed by centrifugation was used to reduce the amount of protein from 0.42 wt% to 0.11 wt%. Structure-modified nanosilica with Silane A174 was used as an additive to reinforce the deproteinized films. The addition of 1 phr of the modified nanosilica exhibited better tensile strength, tensile force at break, modulus at 500% and elongation at break which were improved significantly compared to those of bare films. The modified nanosilica dispersed uniformly in the rubber matrix with the nanoparticle size less than 100 nm observed from the scanning electron microscope. The prepared rubber films containing the modified SiO2 nanoparticles have great potential to produce the NR gloves having very tiny amounts of protein for medical use which still provide the good mechanical strength compared to the standard ones.

Effects of Former Surface Treatment on Natural Rubber Latex Deposition

The glove formers are tools used to pick up the coagulants and rubber latex, so the vulcanised rubber takes the form of hands upon drying. As the demands of gloves quality is crucial to serve the purpose of gloves as a bidirectional protective barrier; the gloves are required to be both sturdy and strong as to prevent tearing while also being elastic and comfortable to use. This research is a comparison study on the surface treatment of a ceramic glove former and how it affects the contact angle between the former surface and the coagulant, and the latex being deposited on the former. The study also focuses on the mechanical properties of the gloves and defects produced by the formers. Gloves were made using the two types of formers and the gloves were then tested for their masses, thickness distributions, tensile strengths, elongations and defects. It was found that the talc treated formers was able to adhere coagulant better, a lower contact angle of 22.10 as compared to the untreated former which had a contact angle of 27.60. This enabled the talc treated former to produce natural rubber gloves which had higher mass and more evenly distributed.

Efficient stoneware hand mold for slip casting in natural rubber latex glove preparation

Disposal medical gloves are an important product to maintain hygienic conditions, ensuring security for patients and safeguarding against infections. They are used in many fields, such as dental and medical, beauty and cuisine, food and pharmaceutical industries. Presently, aging populations and an emerging middle class in developing countries require medical gloves at a higher volume. Therefore, the demand for medical gloves increases continuously. In this work, two types of hand molds were prepared from stoneware clay and plaster to be used in the natural rubber glove preparation. The ceramic stoneware and plaster hand molds were prepared by the slip casting. The obtained stoneware hand molds were found to be superior to the commercial hand molds. Natural rubber latex (NRL) gloves were fabricated by dipping the stoneware hand mold coated with a coagulant into the NRL compound using the sulfur curing system at 120°C for 30 min. The latex solid:water weight ratio, drying and firing temperatures, and firing time used to prepare stoneware hand molds were found to affect the adsorption–adhesion properties between the mold surface and the NRL films. The obtained NRL films were further characterized for the physical properties such as appearance, film thickness, tackiness, and effusion of the phase formation by X-ray diffraction, the microstructure by scanning electron microscope, and the mechanical properties. The NRL glove films prepared by the stoneware hand mold possessed the high percentage elongation at break and the maximum load stress equal to 1343.30 ± 78.36% and 12.74 ± 2.34 MPa, respectively. On the other hand, the latex glove films prepared by the plaster hand mold with 80 consistency provided the percentage of elongation at break and the maximum load stress equal to 531.76 ± 2.54 and 21.01 ± 0.08 MPa, respectively.

Synergistic improvement of mechanical and magnetic properties of a new magnetorheological elastomer composites based on natural rubber and powdered waste natural rubber glove

Abstract Recycling of rubber waste and finding the effective methods to extend its use are one of major challenges nowadays. In the present study, waste natural rubber glove (wNRg) was used in an attempt to extend its use and create a value-added composite based on natural rubber (NR) and wNRg. Another interesting focus was to develop such material into a new Magnetorheological Elastomer (MRE). This MRE can be prepared by incorporating Ferromagnetic particles namely carbonyl iron (CI) to the rubber composite. Carbon black (CB) was also added to obtain MRE with remarkably mechanical properties. CI was fixed at 60 phr where the CB was varied from 10 – 30 phr. Higher thermal conductivity and magneticity in nature of CI had made the composites faster cure and higher magnetic strength. On the contrary, superior tensile strength, modulus and elongation at break were found in the presence of CB. From the experimental results, hybridization of 60/10 phr/phr of CI and CB is highly suggested to gain the synergistic strength and magneticity. This is expected to solve a big problem in the application of MRE.

Recycled Rubber from Waste of Natural Rubber Gloves Blending with Polypropylene for Preparation of Thermoplastic Vulcanizates Compatibilized by Maleic Anhydride

Recycled rubber from waste of natural rubber gloves was prepared via thermo-mechanical de-vulcanization using diphenyl disulfide as a de-vulcanizing aid. After de-vulcanization, the recycled rubber has a higher soluble fraction and a lower cross-link density than that of untreated rubber waste. The de-vulcanization efficiency was then analyzed by Horikx’s method and it was found that random scission or non-selective breakdown of the rubber network, due to both main chain and cross-link scission had occurred during de-vulcanization. Thermoplastic vulcanizates based on recycled rubber and polypropylene blends were prepared using the dynamic vulcanization technique in an internal mixer. Maleic anhydride was used as a chemical modifier in the thermoplastic vulcanizates. The effect of the maleic anhydride loading level was also studied. It was found that the mechanical and rheological properties of the thermoplastic vulcanizates improved with an increasing maleic anhydride content. Furthermore, it was confirmed by SEM morphological investigation that an increasing maleic anhydride content caused a decrease in the size of the spherical dispersed vulcanized rubber domains in the continuous polypropylene matrix. A maleic anhydride content of 80 meq was found to be the optimum content for the improvement of the phase compatibility of the thermoplastic vulcanizates.

Protein reduction of natural rubber films through leaching solvent

The finished product natural rubber latex gloves consist of latex proteins, which may pose a risk of allergic reactions in some latex-sensitive individuals. The allergic reactions depend on mild exposure to heavy exposure. An alternative solution to allergic users, usage of latex-free gloves are lack of elasticity and less comfort. This study aims to investigate natural rubber films protein reduction via three types of leaching solvent: acetic acid, sodium hydroxide, and ethanol in the leaching process. Then the influence of leaching solvent concentration on the physical properties of natural rubber gloves was analyzed. It was found that the acetic acid performed greater protein reduction effect (30.07%), followed by sodium hydroxide (27.77%), whereas the ethanol was shown to be less significant to protein reduction. All samples were fulfilling the mechanical properties as required in ASTM standard.