Skim Natural Rubber 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

Properties of vulcanised concentrated skim natural rubber latex dipped film

Properties of vulcanised concentrated skim natural rubber latex dipped film

Liquid-Phase Exfoliation of Graphite Using the Serum from Skim Natural Rubber Latex

Liquid-Phase Exfoliation of Graphite Using the Serum from Skim Natural Rubber Latex

Preparation of skim natural rubber and polypropylene blends via melt blending: A study on physico-mechanical properties

High percentage of non-rubbers in Skim Natural Rubber (SNR) has restricted its use in manufacture of advanced rubber products. SNR were melt blended with polypropylene (PP) at different blend ratios to generate thermoplastic elastomers (TPEs). Standard Lanka Rubber (SLR) and PP blends were also prepared for the purpose of comparison. Tensile, hysteresis, hardness, water absorption, and dynamic mechanical properties of unvulcanized (UV) and dynamically vulcanized (DV) SNR/PP and SLR/PP blends were compared. Stress-strain behavior and TPE characteristics of both blends were similar. Tensile strength and modulus of SNR/PP blends decreased with the increase of SNR percentage. Elongation at break showed a decrease in UV blends and maxima at 50:50 blend ratio for DV blends. Dynamic vulcanization of the rubber phase improved tensile properties and hardness of the blends. Water absorption studies showed significantly higher equilibrium moisture content in SNR/PP blends, while difference in this property diminished with the increase of rubber phase. Water absorption and equilibrium moisture content decreased with dynamic vulcanization of rubber phase. Dynamic mechanical analysis confirmed multi-phase microstructure of the blends. Both blend systems showed similar dynamic mechanical properties and almost comparable thermo-mechanical properties confirming the potential of SNR as an alternative to SLR for selected applications.

Preparation of skim natural rubber and polypropylene blends via melt blending: A study on processability

Processability of thermoplastic natural rubber (TPNR) blends is a vital aspect in the preparation of blends for industrial applications and is assessed using different techniques. In this study, skim natural rubber/Polypropylene (SNR/PP) blends were prepared using melt mixing and their processability was examined in terms of mixing torque development, long-term processability, moving die rheometer (MDR) torque, thermo-gravimetric analysis (TGA), melt flow index (MFI) and morphological studies. A series of unvulcanized (UV) and dynamically vulcanized (DV) blends having 70/30, 60/40, 50/50, 40/60, and 30/70 SNR/PP compositions were prepared. Standard Lanka Rubber (SLR) and PP blends having corresponding ratios were also studied for the purpose of comparison. The study reveals that a high percentage of non-rubbers present in the SNR has positively influenced the processability of both UV and DV SNR/PP blends compared to SLR/PP blends as assessed by the mixing torque values. As suggested by the mixing torque development and long-term processability, natural rubber dominant both DV blends cannot be processed. However, they can be processed under low shear rates as shown in the MDR studies irrespective of the rubber type. Therefore, it can be inferred that these rubber dominant blends can be processed into molded products via compression molding technique. TGA studies revealed that a similar degree of protection has been offered to the blends against thermal degradation by SNR and SLR. MFI studies showed that there is no significant difference in flowability between UV SNR/PP blends and SLR/PP blends. However, for DV blends, SNR/PP blends showed a higher flowability than SLR/PP blends. In addition, increase in PP percentage in the blend enhances the flowability while dynamic vulcanization reduces the flowability irrespective of the type of rubber used in the blends. Morphological studies suggest continuous or co-continuous phase structures for UV blends and two-phase structures for DV blends where the plastic phase acts as the continuous phase.

E-beam induced grafting of binary monomer on polysulfone membrane for the separation of skim natural rubber latex

Polysulfone (PSF) membranes containing TiO2 were prepared by phase inversion. The membrane surfaces were modified by electron beam irradiation at energies of 3 and 10 MeV for irradiation doses of 10 and 50 kGy. Hydrophilic sulfonate groups were then introduced by single-step grafting using a binary monomer of acrylic acid (AAc) and sodium styrene-sulfonate (SSS). The surfaces of the modified membranes were characterized by analysis of water contact angles (WCA), surface energy (SE), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Filtration performances were evaluated using bovine serum albumin (BSA) and NR serum. A membrane irradiated at 10 MeV and 50 kGy showed the highest hydrophilicity after AAc/SSS grafting, with a WCA of 35.2 degrees and SE of 60.1 mJ/m2. After 2nd cycle filtrations of BSA and NR serum, this membrane demonstrated flux recovery ratios of 97.8% and 95.9%, respectively. The rejection rates of total solid content (TSC) and total protein in NR serum were 72.1% and 91.5%, respectively.

Photocatalytic Degradation of Skim-Latex-Vapor Odor Using Iron-Doped Zinc Oxide

The photocatalytic degradation of the vapor odor of skim natural rubber latex, which is composed of volatile organic compounds (VOCs-NR), was conducted using iron-doped zinc oxide (Fe-ZnO) photocatalyst nanoparticles. The research objectives were to study the photocatalyst, to develop the photocatalytic reactor used for the photodegradation of VOCs-NR, and to analyze the odor reduction of the degraded VOCs-NR. Fe-ZnO was prepared by the sol-gel method and immobilized onto fiberglass cloth as the support material, followed by annealing. The Fe-ZnO nanoparticles were dispersed on the fiberglass surface. A photocatalytic reactor was developed for the gas phase. The research findings showed that gas chromatography-mass spectroscopy detected 24 dominant chemical components in the VOC-NR stock before photocatalytic degradation. The components decreased to 11 after 30 min, only 3 components remained after 40 min of the photocatalytic process, and no component was observed after 80 min of photoirradiation. An organoleptic test was conducted to validate that the odor degraded to a very low level.

Silver nanoparticle synthesis using the serum obtained after rubber coagulation of skim natural rubber latex with chitosan solution

Silver nanoparticle synthesis using the serum obtained after rubber coagulation of skim natural rubber latex with chitosan solution

L-Quebrachitol from acidic serum obtained after rubber coagulation of skim natural rubber latex

A scheme for retrieving l-quebrachitol, which is a starting material for drugs to treat diabetes and cancer, from the acidic serum obtained after acid coagulation of rubber particles in skim natural rubber latex was proposed in this work. The serum was firstly treated with Ba(OH)2, cationic and anionic exchangers and then with activated carbon. The mixture was finally crystallized with ethanol 3 times consecutively. After evaporating the remaining liquid, the white solid was obtained and characterized with FTIR and HPLC-ELSD techniques. The results of mass, pH, electrical conductivity and % Brix values were reported for each stream in the process so that the experiment could be repeated. It was found that the FTIR spectra had characteristic peaks similar to those of the commercial l-quebrachitol and the HPLC results showed that the solid contained a large fraction of l-quebrachitol with small fractions of other impurities. The proposed process could be annexed in the concentrated rubber industry without any modification of the conventional operation.

Permeation of salicylic acid through skim natural rubber films

The skim natural rubber latex (SNRL) with about 4 wt% dry rubber content was incubated with 0.012 wt% urea and 0.025 wt% ethanol both without and with stirring for various times to yield deproteinized rubber films (DSNR). The extractable protein (EP) content was determined by modified Lowry method. The salicylic acid permeation through rubber films was checked by measuring the concentration on the sink side at various times by using spectrophotometer at the wavelength of 344 nm. The studies show that after SNRL were incubated both without and with stirring, the up-and-down patterns of EP contents were seen along the incubation time. Incubation with stirring significantly reduced the EP content and the minimum was seen when SNRL was incubated for 1 h with 52% reduction. The findings also suggest that the SNRL film with a higher EP content yielded the higher the flux. The permeation kinetics through SNR films followed Fickian diffusion. Apart from being more easily peeled of glass plates, SNR films containing higher EP contents were superior to HANR films for their higher permeation fluxes. In addition, the flux of the SNR/HANR blend increased with increasing SNR fraction so the permeation rate could be controlled by adjusting the blend ratio.

การสังเคราะห์อนุภาคเงินระดับนาโนเมตรในหางน้ำยางธรรมชาติสำหรับเซลล์สุริยะชนิดสีย้อมไวแสง

การสังเคราะห์อนุภาคเงินระดับนาโนเมตรในหางน้ำยางธรรมชาติสำหรับเซลล์สุริยะชนิดสีย้อมไวแสง

Compatibility enhancement of silica and natural rubber compound using UVA-induced silane-grafted saponified skim natural rubber

Silane coupling agents are potential reagents widely used to improve the compatibility between silica and less polar rubber, especially natural rubber (NR). Nevertheless, high temperature is generally required to generate the interaction between the components during the mixing process. Accordingly, an alternative method by grafting the silane coupling agent onto the rubber molecules would be a desirable approach to develop a compatibilizer for the silica-filled NR compound. In this work, skim NR was used as a starting material due to its linear structure. The optimal conditions of the grafting reaction were found to be 1 phr of an alkoxy silane and 5 phr of benzoyl peroxide under 8 min of UVA irradiation time. These conditions were applied for producing the rubber material used in the mixing process of STR 5L and silica. The cure characteristics, silica dispersion and mechanical properties of the rubber compounds were improved, suggesting that the modified rubber was an efficient material for increasing the compatibility between silica and NR.

The Effects of Bagasse Fiber Loading on the Mechanical Properties of Skim NR–Clay Nanocomposites

Skim natural rubber (NR)–clay nanocomposites were prepared by a coagulation method using the organoclays Cloisite 15A, Cloisite 20A and Cloisite 30B. This work investigated the use of bagasse fiber developed from locally sourced and renewable material as an alternative and/or secondary filler in skim NR–clay nanocomposites. Bagasse fiber loading in the nanocomposites was 0, 5, 10 and 20 phr; the effects of fiber content on cure characteristics and mechanical properties were then determined. The results suggest that the Mooney viscosity tended to increase with increasing fiber content, whereas the cure time at 90% and fatigue testing score decreased as fiber loading increased.

The Role of Ammonia in Synthesis of Silver Nanoparticles in Skim Natural Rubber Latex

Silver nanoparticles (AgNPs) were synthesized in skim natural rubber latex, the by-product from concentrated latex production. The role of ammonia was investigated by varying the concentration to be 0.217, 0.362, 0.377, 0.392, and 0.406 wt%. The emergence of AgNPs was detected by UV-visible spectrophotometer and electrical conductivity meter. Upon increasing ammonia concentration, the ABS peak increased to a maximum and slightly shifted to a higher wavelength and then it decreased afterward and slightly shifted to a lower wavelength. The shift of the ABS peak was consistent with the conductivity result. The kinetic model was proposed to explain the competition between the reducing effect and size-controlling effect of ammonia. The reducing effect seemed to dominate in the low range of concentration while the size-controlling effect via the formation of AgNH32+ complex ion was important in the higher range. The TEM figures evidently confirmed the effects.

Synthesis of silver nanoparticles in skim natural rubber latex at room temperature

Silver nanoparticles (AgNPs) were synthesized in low cost skim natural rubber latex by adding silver nitrate as a source of silver ions. Left-over ammonia in latex was believed to form a complex with silver ions before reacting with the reducing agents which were glucose and other organic compounds in latex. Moreover, protein in latex could also control the growth of the particles by acting as a stabilizing agent. Many factors, which include ammonia content, d-glucose content and BSA protein content, were studied to clarify their effects in the synthesis. The emergence of AgNPs was checked with UV–visible spectrometer and electrical conductivity meter. Transmission electron microscope (TEM) was applied to study the particle morphology. The results showed that UV absorbance (ABS) and conductivity of the reacting suspension increased when ammonia content and d-glucose content increased, implying an increasing number or growth of particles. In contrast, ABS and conductivity decreased with increasing BSA content, showing that smaller particles were formed. The TEM images confirmed that the size of AgNPs in the none-added sample was 6–26nm. The synthesized AgNPs could inhibit the growth of Escherichia coli and Staphylococcus aureus.

Effect of Grafting Conditions on NR-s-g-HFMA Copolymer and its Thermal Stability

<p>Skim natural rubber (NR-s) is solidified by skim natural rubber latex. NR-s is often evaluated to low grade natural rubber because of its many bad properties such as poor resistance to aging. In order to improve the NR-s comprehensive property, fluorinated groups were incorporated into NR-s molecular chain by grafting via solution polymerization method. The grafted copolymer was characterized and the effects of conditions on grafting ratio and grafting efficiency were investigated. The thermal stability are also examined.</p>

Value Adding of Skim Natural Rubber by Grafting with Maleic Anhydride

This research investigates the potential for grafting skim natural rubber with maleic anhydride to produce maleated rubber with the aim to increase value of skim natural rubber. In this study, grafting of skim natural rubber was compared to those of natural rubber block. Moreover, the effect of protein in skim rubber was also investigated by comparing with grafting of deprotinized skim rubber. Here, the grafting reactions were carried out by reactive melt-mixing method. The effect of maleic anhydride concentration and type of raw materials were investigated. Quantities of the grafted anhydride (MA) and the amount of double bonds were determined by using FTIR analysis.We found that nitrogen content of raw material could potentially affected the grafting level, especially at low MA content, and that the grafting reaction occurred in parallel with crosslinking reaction(gel). The potential model of reaction mechanism was analyzed from FTIR spectra and the gel content.

Extraction of protein from skim natural rubber latex using PEG as a surfactant via low speed centrifugation and continuous flow

ABSTRACTProtein extractions from skim natural rubber latex using 3 %w/v polyethylene glycol (PEG6000) via both low speed centrifugation and continuous flow were investigated. In centrifugal extraction, when the speed was 1000 rpm, the extractable protein (EP) content in serum increased with processing time from 5 to 30 min and when the time was fixed at 5 min, EP content increased with centrifugal speed. In addition, further washing deproteinized chips with 2 %w/v SDS solution could remove proteins with efficiencies corresponding to the efficiencies of protein removals in latex phase, implying the role of PEG in protein reduction in both steps. In continuous flow extraction, EP content increased with increasing Reynolds number or increasing mean residence time of the flow to a maximum and then dropped. The efficiencies of the centrifugal extraction and continuous flow extraction were 55.2 and 33.7%, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39900.

Recycling of Cellulose Ethers from Skim Natural Rubber Recovery Process

Recycling of Cellulose Ethers from Skim Natural Rubber Recovery Process

Use of Cellulose Ethers as Creaming Agents for Skim Natural Rubber Latex

Use of Cellulose Ethers as Creaming Agents for Skim Natural Rubber Latex