Latex Compound Research Articles

The biosynthesis of ZnO nanoparticles using Synadenium grantii latex: characterization and evaluation of their antimicrobial activities

The steadily rising incidences of microbial and infectious diseases pose a direct threat to both human and animal sustainability. Over the previous 20 years, the expectations for eco-friendly nanoparticles application as contemporary medicinal agents have grown. This is why, as opposed to using hazardous chemicals, researchers have recently concentrated on simple, green, sustainable, and affordable ways to create nanoparticles. This research aimed to use the latex of Synadenium grantii to synthesize ZnO NPs (zinc oxide nanoparticles) using a simple and environmentally friendly technique. The observation of the maximum wavelength at 365 nm using Ultraviolet-visible (UV-Vis) spectrometry signified the formation of zinc oxide nanoparticles. The FT-IR (Fourier transform-infrared) spectrometry indicated the bands of various biomolecules (mainly polyphenols at 1541 cm-1 wavenumber) involved in reducing and capping zinc oxide nanoparticles. The XRD spectrum demonstrated the wurtzite phases of ZnO nanoparticles of 24 nm in size. The synthesized ZnO NPs demonstrated great anti-microbial potency compared to the positive control (ampicillin) as tested on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The study confirmed the presence of various chemical compounds in latex of Synadenium grantii responsible for the synthesis of ZnO NPs with enhanced anti-bacterial effects in comparison to the latex extract.

Dual cross‐linking of XNBR latex with epoxy‐functional calcium silicate particles for the production of accelerator‐free medical gloves

AbstractIn this work, an innovative dual cross‐linking strategy for carboxylated nitrile butadiene rubber (XNBR) latex using epoxy‐modified calcium silicate particles is presented. In their role as dual cross‐linker, the particles are able to form covalent bonds (nucleophilic ring opening of epoxy moieties) as well as ionic cross‐links (calcium ions of the inorganic core) across the carboxylic acid groups of the rubber. To characterize the curing efficiency, thin elastomer films are prepared by using a conventional coagulant dipping process and their cross‐link densities, curing kinetics, and tensile properties are investigated as a function of the concentration of the cross‐linker and curing time. The results show that latex films containing 5 phr of epoxy‐functional particles give the highest tensile strength, which is further improved by pre‐vulcanizing the liquid latex compound at 60°C for 30 min. The latex formulations are stable over 3 days and the pre‐cured films exhibit a high resistance against gamma sterilization and subsequent accelerated aging. Moreover, sterile films do not cause any skin irritation or skin sensitization reactions, showing the high potential of epoxy‐functional particles in the production of accelerator‐free hypoallergenic gloves.

Enhancing Latex Compounds and Vulcanized Rubber Properties with Silver Nanoparticles

The production process of latex products requires the preparation of latex compounds by mixing latex with chemicals in a dispersion state. This experiment investigated the influence of added zinc oxide and silver nanoparticles on the properties of latex compounds and vulcanized rubber. It was found that increasing the amount of zinc oxide in the rubber compound resulted in a rise in the viscosity of the latex over the storage period. Increasing the zinc oxide content also led to a higher degree of crosslink noticed by a faster chloroform number determination of the vulcanization level and the opposite effect on the swell value of the rubber film with reduced swelling. The amount of 2.0 phr of ZnO as an activator gave the highest value of the tensile strength. The increasing amount of silver nanoparticles caused a decrease in the viscosity and exhibited a slower chloroform number with a decrease in the swelling of the rubber film. The amount of silver nanoparticles in the study period (0.0010-0.0022 phr) had little effect on mechanical properties but a significant effect on antibacterial activity. The 0.0010 phr of silver nanoparticles showed sufficient potential in inhibiting Staphylococcus aureus and Escherichia coli.

Classification of the Crosslink Density Level of Para Rubber Thick Film of Medical Glove by Using Near-Infrared Spectral Data.

Classification of the crosslink density level of para rubber medical gloves by using near-infrared spectral data combined with machine learning is the first time reported in this paper. The spectra of medical glove samples with different crosslink densities acquired by an ultra-compact portable MicroNIR spectrometer were correlated with their crosslink density levels, which were referencely evaluated by the toluene swell index (TSI). The machine learning protocols used to classify the 3 groups of TSI were specified as less than 80% TSI, 80-88% TSI, and more than 88% TSI. The 80-88% TSI group was the group in which the compounded latex was suitable for medical glove production, which made the glove specification comply with the requirements of customers as indicated by the tensile test. The results show that when comparing the algorithms used for modeling, the linear discriminant analysis (LDA) developed by 2nd derivative spectra with 15 k-best selected wavelengths fairly accurately predicted the class but was most reliable among other algorithms, i.e., artificial neural networks (ANN), support vector machines (SVM), and k-nearest neighbors (kNN), due to higher prediction accuracy, precision, recall, and F1-score of the same value of 0.76 and no overfitting or underfitting prediction. This developed model can be implemented in the glove factory for screening purposes in the production line. However, deep learning modeling should be explored with a larger sample number required for better model performance.

The Role of Plant Latex in Virus Biology.

At least 20,000 plant species produce latex, a capacity that appears to have evolved independently on numerous occasions. With a few exceptions, latex is stored under pressure in specialized cells known as laticifers and is exuded upon injury, leading to the assumption that it has a role in securing the plant after mechanical injury. In addition, a defensive effect against insect herbivores and fungal infections has been well established. Latex also appears to have effects on viruses, and laticifers are a hostile environment for virus colonization. Only one example of successful colonization has been reported: papaya meleira virus (PMeV) and papaya meleira virus 2 (PMeV2) in Carica papaya. In this review, a summary of studies that support both the pro- and anti-viral effects of plant latex compounds is provided. The latex components represent a promising natural source for the discovery of new pro- and anti-viral molecules in the fields of agriculture and medicine.

Surfactants affect urea deproteinization and subsequent prevulcanization of natural rubber latex

Effects of surfactants (sodium dodecyl sulfate (SDS), ammonium laurate (AL), Triton 100-X (TRIX)) on urea deproteinization and sulfur prevulcanization of natural rubber (NR) latex were investigated. A minimum quantity of a surfactant was used consistent with the need to achieve stabilization (prevention of coagulation) of the latex. Irrespective of the surfactant, urea effectively deproteinized the latex to reduce the protein content to ≤0.03% nitrogen. However, AL was the only surfactant that destabilized the deproteinized NR (DPNR) latex compound by forming zinc complexes with the zinc-containing vulcanizing agents. Adding KOH during vulcanization to NR latex that had been deproteinized with urea in the presence of either SDS or TRIX, significantly increased the crosslink density and enhanced the mechanical properties of the resulting films so that they exceeded the Standard ASTM D3578-19 for rubber gloves.

EFFECTS OF FOAMING PARAMETERS ON PHYSICAL PROPERTIES OF MICROWAVE-VULCANIZED NATURAL RUBBER LATEX FOAMS (IVCST2021)

This work reported the use of microwave vulcanization coupled with Dunlop process to prepared natural rubber latex foam (NRLF). Optimization of microwave heating for curing step was firstly carried out using a commercially available domestic microwave oven. The processing window and optimum condition for making NRLF were obtained. The optimum power and time of the irradiation were found at 600 W and 6 min, respectively. Using the optimum microwave vulcanization, effects of stirring time (2, 4, 6, 8, and 10 min) and speed (650, 950, 1250, 1550, and 1850 rpm) of foaming step on cell structure, bulk density, compressive properties, and hardness of NRLFs were investigated. Generally, the increases in the stirring time and speed in foaming step both gave rise to the volume of the air incorporated into the latex compound. This resulted in the increases in the bulk density and the number of cell but, the decrease in foam cell size. The stirring speed in a range of 950 to 1550 rpm was successfully used for preparing the NRLF. Too low and too high foaming speeds caused unstable latex compounds and failed to produce NRLF. The foam cell structure changed dramatically as the foaming speed increased. The foam mechanical properties, both compressive strength and hardness, were found to be linearly related to the foam bulk density.

Utilization of engineered silicate dispersion as a cost-effective cheapener and engineered carbonate dispersion as novel reinforcing additives for nitrile latex glove application

Utilization of silicate minerals fillers in latex offer dual function as a compatible filler and cheapener that economical way to reduce latex consumption. This research explores the effect of using Engineered Silicate Composite Dispersion (ESD 086) as fillers for nitrile latex-supported gloves, seeking to explore their properties while ensuring cost-effectiveness. The reinforcement effect of novel Engineered Carbonate Dispersion (ECD 011) for ESD 086 filled Carboxylated Nitrile Butadiene Rubber (XNBR/ESD 086) latex films has also been explored. XNBR latex films were compounded with three variants of ESD 086 at different loadings (in phr). From three variants of ESD 086 fillers, variant ESD 086A at 10 phr shows the highest tensile strength. As the ESD 086A filler loading increased up to 15 phr, the tensile strength decreased, indicating the ineffectiveness to be used at higher loading. The work was continued by exploring the use of novel ECD 011 to minimize the decrement effect. The 15 phr ESD 086 filled XNBR latex films (XNBR/ESD 086A-15) were subjected to a hybrid loading from 0 to 1.2 phr with 0.2 phr staggered increment together with the reduction of ECD 011:ZnO ratio in the XNBR latex compounds. Results show that at 0.6:0.6 phr of ECD 011:ZnO, the tensile strength of XNBR/ESD 086A-15 latex films increased and the elongation at break also improved. Using ESD 086A can reduce the usage of XNBR latex. Still, it can only be used up to 10 phr (optimum loading) and ECD 011 can maintain the physical properties and offer maximum cost-saving options for XNBR latex glove formulation at higher loading of ESD fillers. Overall, both engineered dispersions offer potential commercial benefits for the Nitrile gloves industry.

Effect of disaggregation and activation of sepiolite on interfacial interaction and mechanical properties of natural rubber/sepiolite composites prepared by latex compounding method

AbstractThe demand for environmentally friendly and non‐petroleum based natural rubber products is on the rise. Sepiolite, a one‐dimensional clay mineral, has been found to be a suitable reinforcement for natural rubber through latex compounding. However, the aggregation of fibers and minerals may impact the overall properties of natural rubber composites. To overcome this challenge, the study utilized ultrasonic disaggregation and oxalic acid activation to prepare stable sepiolite suspensions with varying specific surface areas and surface activities. These suspensions were then mixed with natural rubber latex to prepare NR/sepiolite composites. The results showed that the dispersibility and bonding ability of sepiolite with natural rubber were improved due to the increased specific surface area and surface activity, resulting in more bonding sites. The mechanical properties of the composites were also found to be improved, with a significant increase in tear strength (from 61.9 to 67.6 N·mm−1) and tensile strength (from 23.0 to 29.5 MPa). This research lays a strong foundation for the utilization of sepiolite in rubber materials.

Effect of Different Silane Coupling Agents In-Situ Modified Sepiolite on the Structure and Properties of Natural Rubber Composites Prepared by Latex Compounding Method

With the increasing demand for eco-friendly, non-petroleum-based natural rubber (NR) products, sepiolite, a naturally abundant, one-dimensional clay mineral, has been identified as a suitable material for reinforcing NR through the latex compounding method. To create superior NR/sepiolite composites, three silane coupling agents with different functional groups were used to modify sepiolite in situ via grafting or adsorption during the disaggregation and activation of natural sepiolite, which were subsequently mixed with natural rubber latex (NRL) to prepare the composites. The results showed that the modified sepiolite improved the dispersion and interfacial bonding strength with the rubber matrix. VTES-modified sepiolite containing C=C groups slightly improved the performance but retarded the vulcanization of the NR composites, and MPTES and TESPT-modified sepiolites containing -SH and -S4- groups, respectively, effectively accelerated vulcanization, inducing the composites to form a denser crosslink network structure, and exhibiting excellent dynamic and static properties, such as the modulus at a 300% increase from 8.82 MPa to 16.87 MPa, a tear strength increase from 49.6 N·mm-1 to 60.3 N·mm-1, as well as an improved rolling resistance and abrasive resistance of the composites. These findings demonstrate that modified sepiolite can be used to produce high-quality NR/sepiolite composites with enhanced properties.

Effects of Bamboo Leaf Fiber Content on Cushion Performance and Biodegradability of Natural Rubber Latex Foam Composites.

Bamboo leaf fiber (BLF) was incorporated into an eco-friendly foam cushion made from natural rubber latex (NRL) to enhance the biodegradation rate. The objective of this work was to investigate the effects of BLF content on the foam structure, mechanical properties, cushion performance, and biodegradability. The NRL foam cushion nets with and without BLF were prepared using the Dunlop method along with microwave-assisted vulcanization. BLF (90-106 µm in length) at various loadings (0.00, 2.50, 5.00, 7.50, and 10.00 phr) were introduced to the latex compounds before gelling and vulcanizing steps. Scanning electron microscopy (SEM) showed that the BLF in a NRL foam caused an increase in cell size and a decrease in the number of cells. The changes in the cell structure and number of cells resulted in increases in the bulk density, hardness, compression set, compressive strength, and cushion coefficient. A soil burial test of 24 weeks revealed faster weight loss of 1.8 times when the BLF content was 10.00 phr as compared to the NRL foam without BLF. The findings of this work suggest the possibility of developing an eco-friendly cushion with a faster degradation rate while maintaining cushion performance, which could be a better alternative for sustainable packaging in the future.

The coagulant dipping process of nitrile latex: investigations of former motion effects and coagulant loss into the dipping compound.

Coagulant dipping, the process used in thin glove manufacture, involves electrolyte ions diffusing from the surface of a hand-shaped former into latex compound, causing a deposit (wet gel) to accumulate on the former. In this work, two aspects of the process were examined, both experimentally and theoretically. For the experimental work, a commercial nitrile latex was used. The motion of formers through a latex dipping tank is intuitively expected to affect the electrolyte diffusion and hence the wet gel growth. This was investigated at laboratory scale with small glass formers moving in a metre-long dip tank. Former velocities ranged from zero to almost 0.2 m s-1. No effect of former lateral movement on wet gel thickness was observed. One obvious explanation is that most of the coagulant diffusion occurs within the wet gel deposit, which provides protection to the diffusive flux. However, the critical zone is just ahead of the coagulating front, where coagulant is present in the liquid compound at concentrations below the level needed for coagulation. A fluid mechanical model was constructed that assumed a uniform fluid flow along the side face of a rectangular former. The model confirmed that for calcium nitrate, the most commonly used coagulant, the effect of movement is very small. In the second investigation, coagulant leakage into the host latex compound during the dwell time was investigated by taking samples during repeat static dips. This experiment was modelled using diffusion theory, focusing on the critical zone just outside the wet gel at the point of former withdrawal. The model and experiment agreed well, both showing a small but definite coagulant leakage that tended towards a plateau concentration. Coagulant leakage from a moving former was also considered, from a theoretical perspective. In this case, the mechanism is advective movement of coagulant from the critical zone into the host compound. In the worst case, where all of this coagulant is swept away, the model suggested that the plateau coagulant concentration could reach an amount that would cause coagulation. Reduced flow in the critical zone (boundary layer) and former shape are factors that would reduce leakage.

Effect of Nanocrystal Cellulose Isolated from Empty Fruit Bunches (Elaeis Guineensis Jack) Addition on Morphological and Mechanical Properties of Natural Rubber Latex Product.

The research about the effect of the addition of nano crystal cellulose (NCC) isolated from empty palm bunches (EPB) on the morphological and mechanical properties of natural rubber latex products was successfully conducted. This research was carried out in three steps: i.e isolation of α-cellulose from EPB, followed by isolation NCCs from α-cellulose using H2SO4 48.84% at 45ºC for 25 minutes, and manufacture of latex compound with varying filler NCC were 0, 0.6, 1.2, 1.8, 2.4, and 3.0. Manufacturing of natural rubber product was made with pour the NRL followed by vulcanized at 120ºC for 30 minutes. The sheet of NRL product was produced later characterized its mechanical properties through tensile test and surface morphology analysis by SEM. The optimum value of the tensile test result of the NRL product sheet was at the addition of 1,2 phr of NCC with values of tensile test, elongation at break, and Young’s modulus was 3.771 MPa, 877%, and 0.430 Mpa respectively. In addition, surface morphology analysis showed that the NCC was spread evenly.

Activated calcium silicate/natural rubber composites prepared via latex compounding: Static and dynamic mechanical properties

Activated calcium silicate/natural rubber composites prepared via latex compounding: Static and dynamic mechanical properties

Enhanced Toughness and Sound Absorption Performance of Bio-Aerogel via Incorporation of Elastomer.

In this study, Arabic gum/ carboxylic butadiene-acrylonitrite latex aerogels (AG/XNBRL) hybrid aerogel was successfully prepared by a green method, i.e., the combination of latex compounding and vacuum freeze-drying process. After that, the obtained composites were subjected to a high temperature treatment to crosslink the rubber phase. It was found that the AG in the AG/XNBRL hybrid aerogel could act as a framework to improve the dimensional stability of the aerogel, while the XNBRL phase could significantly improve the mechanical flexibility of the ensuing composite. Compared to the AG aerogel which is highly brittle in nature, the AG/XNBRL hybrid aerogel not only exhibits significantly enhanced toughness, but also shows improved thermal stability and sound absorption performances; for instance, the half weight loss (50%) temperature and average sound adsorption coefficient for aerogel containing 30 wt% XNBRL is 344 °C and 0.585, respectively, which are superior to those of neat AG aerogel. Overall, this work provides novel inspiration to prepare the mechanical robust bio-based aerogel for the sound absorption application.

Oil palm empty fruit bunch cellulose fillers as alternative fillers for carboxylated nitrile butadiene rubber latex films

Malaysia is one of the largest contributors to oil palm plantations and industries, resulting in the generation of a lot of oil palm waste such as oil palm empty fruit bunch (OPEFB). The main goal of this research is to investigate the effect of the OPEFB cellulose as one of the alternative fillers in the carboxylated nitrile butadiene rubber (XNBR) latex films. The OPEFB waste was subjected to ultrasonic with alkali and bleaching treatment prior to addition in XNBR latex compounds. The ultrasonic treatment shows better removal of wax, hemicellulose and lignin but leads to breaking down the crystalline structure of the cellulose particles resulted in reduction of the mechanical properties of the OPEFB cellulose filled XNBR latex films. The OPEFB cellulose filled XNBR latex compound is then subjected to different zinc oxide (ZnO) loading. It found that the increase in zinc oxide loading enhanced the ionic crosslink formation but disrupt the covalent crosslink formation since most of the metal cations Zn2+ tend to form ionic clusters for the ionic crosslinks and Zn-cellulose complex. Overall, the OPEFB cellulose fillers shows positive impact as alternative fillers in XNBR latex films.

A model study on the impact of metal ions on pre-vulcanization of concentrated natural rubber latex and dipped-products

A model study on the influence of some heavy metal ions on the stability and vulcanization efficiency of uncompounded and compounded high-ammonia natural rubber (HANR) latex was carried out by an exogenous addition and then determined by Brookfield viscometer, mechanical stability time (MST) tester, and tensile testing machine. The case of pre-vulcanized HANR latex with different aging times was determined by the change in the volatile fatty acid (VFA) number, MST, and viscosity. The compounded HANR latex was coagulated by adding Mn2+and Mg2+ while it was unaltered by adding Zn2+, Fe2+, and Cu2+ ions, leading to their colloidal stability. Therefore, these metal ions were chosen further to study the pre-vulcanization of compounded HANR latex. The presence of Zn2+, Fe2+, and Cu2+ in the latex is responsible for the delay in the vulcanization process and changes the appearance of compounded latex. Before compounding, the addition of such metal ions led to the reduction in tensile strength of the obtained gloves. At the same time, there was no effect on the tensile properties of the gloves made from the compounded HANR latex containing the metal ions.

Thermal Insulation Performances of Plaster Composites Based on Embedding Natural Rubber Latex Compound

Adding 0, 20, and 50 wt% natural-rubber latex compound into the plaster ceiling matrix affected to increase the physical-mechanical-thermal performance properties of plaster ceiling composites. Adding 50 wt% natural rubber latex compound into plaster composites can increase the superior adhesion of the nail-tensile resistance equal to 57.54 N and decrease thermal conductivity equal to 0.0634 W/m.K. In addition, adding natural rubber latex compounds into plaster composites can reduce water solubility, brittleness, impact, and cost of energy consumption due to the exterior temperature. Adequate thermal insulation for roofing, ceiling, and wall systems also reduces radiative losses that chill occupants in cold weather, and reduce interior surface temperatures in the summer, thereby optimizing the comfort of building occupants. The mechanical and thermal properties of plaster composites were investigated by using a Universal Testing Machine (UTM) and heat flow meter, respectively, measured according to TIS 1211-50, TIS 219-2522, and ASTM C518.

Modifications to improve properties of gypsum ceiling composites as multifunctional construction by embedding Typha angustifolia fiber and natural rubber latex compound

Modifications to improve the physical, thermal, and mechanical properties of gypsum ceiling composites can be made by adding bio-fillers. Adding 1 and 3 wt% of Typha angustifolia fiber in 1D, 2D, or 3D fiber orientations, and adding 20 or 50 wt% natural rubber-latex compound were embedded into gypsum ceiling composites using a casting process. The gypsum ceiling composites added 1 wt% Typha angustifolia fiber 3D orientation (Formula 6, G-3D-1 F) resulted in optimum conditions with high compressive stress, high nail tensile resistance, high thermal shock resistance, low thermal conductivity, and a light weight with values of 315.17 ± 27.40 N, 92.10 ± 3.78 N. The received samples (G-3D-1 F) were no cracking and fracturing after autoclave testing, and 0.0796 ± 0.0005 W/m.K, respectively, better than those of the reference sample (Formula1, G-ref). Furthermore, the received samples were compared to commercial insulation materials such as concrete block, earthenware brick, light concrete brick, and cement brick with thermal conductivity values of approximately 0.546, 0.473, 0.180, and 0.126 W/m.K, respectively. The tested gypsum ceiling composites can be applied for thermal insulation and as decorative materials for construction and building to reduce energy consumption. In addition, the developed gypsum ceiling composites are easy fabrication and operation, non-toxic, inexpensive, and light weight.

Characterization of Blends of Virgin Nitrile Rubber and Compounded Nitrile Rubber Latex Waste Reclaimed with Urea: Part II - Physico-Mechanical Properties

Recycling of rubber waste materials in order to convert these to usable products is one of the main challenges in the rubber industry. Reclaiming of rubber waste and blending it with virgin rubber have increased during the past due to the growing concern on the environment and increase in the prices of synthetic rubbers. Hence, the aim of this study is to partially replace virgin nitrile rubber (NBR) with reclaimed compounded NBR latex waste to develop new rubber blends suitable for special applications. In this study, physico-mechanical properties, ageing performance and swelling behaviour of virgin NBR / reclaimed NBR blend vulcanizates were evaluated and compared with those of the control vulcanizate produced solely with virgin NBR. Results showed that replacement of 50% virgin NBR with reclaimed NBR retained 71-86% of tensile strength, elongation at break and resilience. Hardness and modulus of this blend vulcanizate increased by less than 18%, whereas abrasion volume loss and compression set increased by 27%. Ageing resistance is similar to that of the control vulcanizate. Interestingly, resistance to swelling in toluene and ASTM oil No.3 increased by 14% and 32%, respectively. Hence, the 50:50 virgin NBR / reclaimed NBR vulcanizate would be suitable for oil resistant applications.