Skim Natural Rubber Latex Research Articles

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

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

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

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.

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>

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.

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

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

Factors affecting creaming efficiency of bio-based polymers, vulcanization and mechanical properties of creamed skim rubber

Recovery of skim rubber from skim natural rubber (SNR) latex was studied by using three bio-based polymers, N,O-carboxymethyl chitosan (CMCh), sodium alginate (SA) and carboxymethylcellulose (CMC), as creaming agents. It was observed that creaming efficiency of the bio-based polymers was governed by concentration, viscosity and types of bio-based polymers used but independent of ammonia concentration and dry rubber content of SNR latex. CMCh, SA, and CMC having viscosity in a range of 10 mPa s – 25 mPa s were found to be the excellent creaming agents for SNR latex. Average sizes of rubber particles in the cream phase were not quite different from those of the original SNR latex. The skim rubber in the cream phase could be coagulated by using only a small amount of H2SO4. The obtained skim rubber contained lower protein than the skim rubber recovered by the traditional method using conc. H2SO4 which markedly affected the vulcanization characteristics of the skim rubber. In addition, physical and mechanical properties such as initial Wallace plasticity, modulus at 100% strain, tensile strength and elongation at break of recovered skim rubber were influenced by the use of creaming agents.

Creaming of skim natural rubber latex with chitosan derivatives

AbstractTo recover residual rubber from skim natural rubber (SNR) latex, a novel method was developed on the basis of the use of water‐soluble chitosan derivatives. An anionic chitosan derivative, N,O‐carboxymethyl chitosan (CMCh), and a cationic chitosan derivative, N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTACh), were prepared. It was found that the creaming process could be achieved with both chitosan derivatives. By the addition of 7.34–10.3‐g/L CMCh, SNR latex was almost completely creamed, and no coagulation of SNR particles in the cream phase occurred. In the case of HTACh, the creaming process was achieved with a lower concentration (<3.70 g/L) than in the case of CMCh, but the size of SNR particles in the cream phase was larger. Solid‐state 13C‐NMR, thermogravimetric analysis, and ζ potential measurement results provided evidence that the creaming of SNR latex with CMCh and HTACh was controlled by the depletion flocculation and adsorption mechanisms, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Improving thermal and ozone stability of skim natural rubber by diimide reduction

The physical, chemical and thermal properties of diene-based polymers are improved by a chemical modification method such as hydrogenation. Skim natural rubber (SNR) which is mainly comprised of cis-1,4-polyisoprene was hydrogenated by diimide reduction in latex form, using hydrazine and hydrogen peroxide with copper sulfate as catalyst. The effect of various parameters on the level of hydrogenation calculated from proton nuclear magnetic resonance spectroscopy ( 1H NMR) was investigated. The kinetic results indicated that the diimide hydrogenation of skim natural rubber latex (SNRL) exhibited a first order behavior with respect to the C C concentration. The apparent activation energy of the catalytic and non-catalytic hydrogenation of SNRL was calculated as 9.5 and 21.1 kJ/mol, respectively. From the TEM micrograph of hydrogenated SNRL particles, non-hydrogenated rubber core and hydrogenated rubber layer were observed according to a layer model. The results from thermal analysis confirmed that thermal stability of hydrogenated SNR was improved compared with the starting SNR. In addition, the thermal aging and ozone resistance of vulcanized hydrogenated SNR blends were also investigated.

Effect of field natural rubber latex with different ammonia contents and storage period on physical properties of latex concentrate, stability of skim latex and dipped film

The effect of ammonia treatment in field natural rubber (NR) latex with different storage period time on the properties of concentrated NR latex and stability of skim latex was investigated. Fresh NR latex was treated with various ammonia contents such as 0.35, 0.60 and 0.80% w/w, and then they were centrifuged to get the concentrated NR latex with 60% dry rubber content (DRC) containing 0.16, 0.18 and 0.25% w/w, respectively and skim NR latex with roughly 5% DRC containing 0.42, 0.60 and 0.80% w/w, respectively. The effect of storage times with ∼0, 15, 30 and 45 days for concentrated NR latex with different ammonia contents on their properties such as alkalinity, magnesium content and viscosity was observed. It was found that generally, magnesium content in field NR latex and latex concentrate decreased with storage period times. The alkalinity content in both concentrated NR and skim latex increased with increasing ammonia content in field latex. The viscosity of concentrated NR latex increased as a function of storage period time of field NR latex. The stability of skim latex depends on storage period time of field NR latex with different ammonias. The tensile strength of dipped films obtained from field NR latex with 0.80% w/w of ammonia was dependent on storage period time of field NR latex.

Use of Hydroxypropylmethylcellulose as Thermo-Responsive Flocculant in Skim Natural Rubber Latex

To recover residual rubber from skim natural rubber (SNR) latex, the effective and environmentally friendly methodology developed based on using hydroxypropylmethylcellulose (HPMC) as a thermo-responsive flocculant. The SNR particles could be completely separated to form high concentrated latex as cream phase within only 5 hours. Almost 100% of SNR was recovered when using HPMC 0.7%w/w. Quality of SNR obtained from this technique was higher and color of it was lighter than SNR obtained from the conventional method. HPMC could be easily precipitated from the serum phase by heating the serum phase at about 70 °C. The cloud point and the precipitation point of HPMC were affected by the additions of α-D-glucose, sn-phosphatidyl chloride and inorganic salts. It was found that reduction of the cloud point and the precipitation point of HPMC also depended on both concentration and type of cations and anions of inorganic salts.

Preparation and characterization of organoclay‐rubber nanocomposites via a new route with skim natural rubber latex

AbstractSkim natural rubber latex (SNRL) is a protein rich by‐product obtained during the centrifugal concentration of natural rubber (NR) latex. A new method to recover rubber hydrocarbon and to obtain nanocomposites with organoclay (OC) was investigated. The approach involved treatment of SNRL with alkali and surfactant, leading to creaming of skim latex and removal of clear aqueous phase before addition of OC dispersion. Clay mixed latex was then coagulated to a consolidated mass by formic acid, followed by drying and vulcanization like a conventional rubber vulcanizate. X‐ray diffraction (XRD) studies revealed that NR nanocomposites exhibited a highly intercalated structure up to a loading of 15 phr (parts per hundred rubber) of OC. Transmission electron microscopy studies showed a highly exfoliated and intercalated structure for the NR nanocomposites at loadings of 3–5 phr organically modified montmorillonite (OMMT). The presence of clay resulted in a faster onset of cure and higher rheometric torque. The rubber recovered from skim latex had a high gum strength, and a low amount of OC (5 phr) improved the modulus and tensile strength of NR. The high tensile strength was supported by the tensile fractography from scanning electron microscopy. Thermal ageing at 70°C for 6 days resulted in an improvement in the modulus of the samples; the effect was greater for unfilled NR vulcanizate. The maximum degradation temperature was found to be independent of the presence and concentration of OC. The increased restriction to swelling with the loading of OC suggested a higher level of crosslinking and reinforcement in its presence. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3277–3285, 2006

Studies on natural rubber/acrylonitrile butadiene rubber/organoclay nanocomposites

Skim natural rubber latex (SNRL) is a protein rich byproduct obtained during the centrifugal concentration of natural rubber (NR) latex. Natural rubber/acrylonitrile butadiene rubber (NBR) based nanocomposites were prepared by addition of aqueous organoclay dispersion to SNRL/NBR latex blend obtained after a creaming process, followed by co-coagulation, drying, mill mixing and vulcanisation. X-ray diffraction studies revealed that NR/NBR blend nanocomposites exhibited a highly intercalated structure that was more prominent when the content of NBR in the blend was 50%. The intercalation, level of cross-linking and clay dispersion for the two rubber matrices varied with the composition of the blend. Among the blends, NR/NBR 25 : 75 blend showed enhanced mechanical properties for gum vulcanisates, which was further, improved in the presence of 5 phr organoclay.