Synthesis of h-MoO3 and (NH4)2Mo4O13 Using Precipitation Method at Various pH Values and their Photochromic Properties
Phuriwat Jittiarporn, Lek Sikong, Kalyanee Kooptarnond, Wirach Taweepreda, Pipat Chooto, Matthana Khangkhamano
Applied Mechanics and Materials · 2016
(NH4)2Mo4O13 and h–MoO3 nanocrystalline powders were synthesized by precipitation method at a varied pH range from 5.0 to 1.0. The crystal structure, morphology and optical property of samples were determined by X–ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and UV–vis diffuse reflectance spectrophotometer (UV-vis DRS). At pH 2.0, 3.0 and 5.0, homogenous plate–like (NH4)2Mo4O13 was seen, whereas the heterogeneous hexagonal rod–shaped MoO3 was found at very low pH of 1.0 and 1.5. Band gap energy of the synthesized (NH4)2Mo4O13 and h–MoO3 were 3.38 and 3.18 eV, respectively. Photochromic properties of the products were illustrated by color difference before and after UV irradiation using CIE Lab color system. The synthesized h–MoO3 provided a strong photochromic performance, while the (NH4)2Mo4O13 showed non–photochromic properties. Intercalation of H+ in h-MoO3 were studied using electrochemical characterization by cyclic voltammetry (CV). The diffusion coefficient of the samples increases with decreasing pH of the solution.
Preparation and molecular weight controlled of liquid natural rubber using Mastication
Saengchao Thongseenuch, Sopapan Jindapaisan, Wirach Taweepreda
2016
Natural rubber (NR) can be easily depolymerized because that contain unsaturated component (double bond). Mastication is breaking the rubber molecular chains through mechanical action and thermal in two roll mill. This attention is preparation depolymerized natural rubber, using mastication method with temperature-controlled two roll mill. The effect of temperature and time of mastication on degree of depolymerization were studied and characterized by Gel Permeation Chromatography (GPC). It was found increasing temperature and time of mastication to the resulting decreased average molecular weight of NR.
Preparation and Characterization of Natural Rubber/Chitosan Films
Kansiree Paoribut, Wirach Taweepreda, Kanoktip Boonkerd
Key engineering materials · 2015
Natural rubber/chitosan (NR/CS) films at various NR/CS ratios were prepared here from the mixture of natural rubber latex (NRL) and chitosan solution using a solution casting method. The NRLs with and without sulfur curing agents were used. The NR/CS films were obtained after heating at 50oC for 24 hours. The NR/CS films prepared from the NRL with curing agents were further heated at 120oC for 30 min to acquire the NR networks. From swelling testing, it was found that incorporation of CS into the NR matrix gave the films with higher solvent resistance. The swelling index reduced proportionally with the increased CS loadings. Additionally, the solvent resistance of the NR/CS films was improved more once the NR was cured. In general, for every NR/CS ratio, the tensile strengths of the cured NR/CS films were higher than those of the uncured NR/CS films. After thermal aging, it was found that the tensile strength of the uncured NR/CS films decreased while that of the cured ones increased. Two thermal decomposition peaks were observed. The onset decompostion temperatures at lower and higher temperature were corresponding to the degradation of chitosan and natural rubber, respectively. The initial thermal degradation temperature of CS and NR in the NR/CS films was shifted to the higher temperature than that of the pure CS and NR, respectively.
Investigation of Sulfur Crosslinking Interfacial of Natural Rubber (NR) Blending with Carboxyalted Styrene Butadiene Rubber (XSBR) Using X-Ray Absorption Spectroscopy
Chanaphan Lamlong, Wirach Taweepreda, Rattapong Nu-Mard, Prayoon Songsiriritthigul
Advanced materials research · 2015
The sulfur crosslinking films from Natural Rubber (NR), Carboxylated Stryrene Butadiene Rubber (XSBR) latices, and their blends have been investigated using X-ray absorption near-edge structure spectroscopy (XANES). The film was prepared by casting the latex compound on glass surface and heating at 120oC in a hot air oven for 10 minutes. The sulfur crosslinking density were studied by the XANES. This was done to provide the local geometry and electronic environment of sulfur bonding in the rubber networks. We found that the reversion takes place before the onset of oxidative processes at the sulfur bridges. Parallel to the oxidative processes, the production of cyclic sulfanes takes places. This relationship depends on the rubber compositions.
Surfactant Treatment and Leaching Combination Process for Preparation of Deproteinized Natural Rubber Latex
Jirapornchai Suksaeree, Wirach Taweepreda, Wiwat Pichayakorn
Key engineering materials · 2015
This study aimed to improve the efficacy of protein removal from fresh natural rubber latex (NRL) and to decrease the production cost by using surfactant treatment and leaching combination processes. The 0.5-3% anionic surfactants, i.e. sodium dodecyl sulfate or sodium lauryl ether sulfate, nonionic tween80 surfactant, or an amphoteric cocamidopropyl betaine surfactant was used in surfactant treatment process. Moreover, water, aqueous surfactant solutions, and/or 1-5% organic solvents (i.e. ethanol, isopropanol and/or acetone) was then used in leaching process. The fresh NRL was preserved by paraben compounds in the presence of surfactant at ambient temperature for 20-120 minutes, and then centrifuged. This might prevent the skin irritation of deproteinized NRL (DNRL) caused by ammonium stabilizer that normally uses in latex industry. The upper rubber mass was then leached for upto three cycles with leaching solvents, and then finally redispersed in distilled water. The milky-like DNRLs were obtained by these processes. Their dry rubber contents were 41-47% that could be adjusted. Their viscosities were 9-13 centipoises with the pH of 6.04-6.61. The protein residues in these DNRLs were 0.0000-0.3244% which were lower than that of fresh NRL (1.2428%). These indicated the efficacy of studied deproteinization process for 73.90-100.0%. Types and concentrations of surfactant, incubation times, leaching solvents, and cycles of leaching process affected the efficacy of deproteinization process. Moreover, the properties of these dried films were not different from that of fresh NR film. This DNRL could be further used for several applications including medical skin products.
Properties of Deproteinized Natural Rubber Latex/Gelatinized Starch Blended Films
Rungtiwa Waiprib, Wiwat Pichayakorn, Prapaporn Boonme, Wirach Taweepreda, Jirapornchai Suksaeree
Key engineering materials · 2015
This research aimed to study the compatibility and properties of deproteinized natural rubber latex (DNRL)/gelatinized starch blended films for use as transdermal patches. Various starches were previously gelatinized by heat treatment. Then, the DNRL/gelatinized starch blended films were prepared by simple mixing of DNRL with gelatinized starch and then drying at 50°C. The various parameters such as types (potato, sago, bean, corn, tapioca, rice and glutinous starches), amounts (5, 10, 15 and 20 part per hundred of rubber (phr)) and concentrations of gelatinized starch pastes (5, 10, 20 and 50%) were evaluated. It was found that all starch types could be blended as a homogeneous mixture with DNRL only in 5 phr. Bean starch also provided the good mixture in 10 and 15 phr. Rice and corn starches in the concentrations up to 20 phr could also be blended. Higher concentration of gelatinized starch pastes obtained the higher viscous liquids that were difficult to blend as a homogeneous mixture with DNRL, and provided inhomogeneous blended films. The dried films of all homogeneous DNRL/gelatinized starch mixtures were slightly yellowish transparent with good physical appearances. The tensile strength, swelling and erosion of these blended films increased when increasing amounts of gelatinized starch, but their elasticities were not different comparing to that of DNRL film itself. However, their strengths should be further improved by adding some plasticizers. Some drugs would be further loaded in these homogeneous film formulations for transdermal delivery.
Rheological Behavior Characterization of Natural Rubber Containing Different Gel
Saengchao Thongseenuch, Wirach Taweepreda, Krisda Suchiva
Advanced materials research · 2014
This research, natural rubber containing different gel contents were prepared by deproteinization and saponification treatment from high ammonium natural rubber latex. Deproteinization natural rubber was further treated as acetone extraction and then transesterification. It was founded that gel content and molecular weights of treated natural rubber were decreased and almost absented for transesterification treatment. Rheological respond on small amplitude oscillating shear (SAOS) and large amplitude oscillating shear (LAOS) deformation of treated natural rubber were captured by using rubber process analyzer (RPA 2000). Firs harmonic rheological properties, storage modulus, G and loss modulus, G decreased as gel content and molecular weight decreased. It was believed that gels, explicitly branching points, were destroyed after the natural rubber was deproteinized, transesterification, or saponification according to the molecular structure of natural rubber presumed by Tanaka et al, which functional groups contain protein and fatty acid are participated in branching to forming gel structure. It was concluded that gel content as the same as molecular structure of natural rubber could be characterized as rheological behavior.
Preparation of Positively Charged Membrane from Natural Rubber Latex Blending with Chitosan
Wirach Taweepreda, Supawadee Tuaybut, Sineenart Puangmanee, Tran Dang Khoa
Communications in Physics · 2014
Film formation of natural rubber latex (NRL) blended with various concentrations of chitosan was investigated. Atomic force microscopy (AFM) images clearly showed that the NRL film covered chitosan phase. Roughness of the films which was calculated from AFM image increases with increasing chitosan concentration. Miscibility of NRL and chitosan in solution was investigated by using dynamic mechanical thermal analysis (DMTA) and found that chitosan incorporated with NRL less than 40 weight percentage (wt%) was partially miscible. Films of the chitosan blending with higher NRL contents exhibited two peaks of glass transition temperatures. Interfacial polarization and dielectric properties of polymer films were improved with increasing NRL contents. Chemical structure of the blends was characterized by using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR).
Transdermal nicotine mixed natural rubber-hydroxypropylmethylcellulose film forming systems for smoking cessation:in vitroevaluations
Wiwat Pichayakorn, Jirapornchai Suksaeree, Prapaporn Boonme, Wirach Taweepreda, Thanaporn Amnuaikit, Garnpimol C. Ritthidej
Pharmaceutical Development and Technology · 2014
Novel film forming polymeric dispersions for transdermal nicotine delivery were prepared from deproteinized natural rubber latex (DNRL) blended with hydroxypropylmethylcellulose (HPMC) and dibutyl phthalate (DBP) or glycerin (GLY) as plasticizer. The preliminary molecular compatibility of ingredients was observed by Fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray diffractometry characterizations. All film forming polymeric dispersions were elegant in appearance and smooth in texture without agglomeration. Their pH was 7-8. In addition, their viscosity and spreadability showed good characteristics depended on HPMC and plasticizers blended. The transparent in situ dry films with good strength and elasticity were also confirmed by peeling-off. The nicotine release from them revealed an initial fast release that was similar to the release from a concentrated nicotine solution, and followed by slow release pattern from the in situ films. GLY blended formulation produced a higher amount of nicotine permeation through the in vitro pig skin than DBP blends. Ethanol mixing also enhanced nicotine permeation, but it affected the integrity of in situ films. The nicotine release and skin permeation kinetics were by a diffusion mechanism that was confirmed by the Higuchi's model. These formulations were safe without producing any severe skin irritation. However, for the stability they needed to be stored at 4 °C in tightly sealed containers.
Electrospun Conditions of Poly(vinyl chloride) Nanofibrous Membrane Plasticized with Polyurethane
Kritsada Phatcharasit, Wirach Taweepreda, Kanoktip Boonkerd, Jin‐Kuk Kim
Jurnal Teknologi · 2014
Electrospun poly(vinyl chloride) (PVC) nanofibrous were prepared by electrospinning. Various concentration of polyurethane (PU) were added to PVC solution for plasticization of the electrospun nanofibrous. The pristine and plasticized nanofibrous were characterized by field emission scanning electron microscopy (FE-SEM), differencial thermal analysis (DTA), and thermogravimetry analysis (TGA), respectively. Thermal properties form DTA and TGA results indicated that the addition of PU decreased glass transition temperature (Tg) of PVC and increased heat resistance of PVC nanofiber. The dielectric constant of plasticized nanofibrous measured using precision LCR meter indicated that the membrane were dense.
Influence of N-Doped TiO2 Nanocomposite Film on Hydrophilic Property of Rubber Dipping Former Surface
Mahamasuhaimi Masae, Lek Sikong, Kalayanee Kooptarnond, Wirach Taweepreda, Fumio Saito, Pichaya Pitsuwan
Key engineering materials · 2014
The objective of this study is to explore a method to improve hydrophilicity of the surface of formers that could be more easily dipped to produce high quality dipped rubber products. Photocatalytic TiO2 composite films were prepared by sol-gel method. Glass formers were coated with nitrogen doped TiO2 nanocomposite film by dipping method and annealed at 600°C for 1 h. Phase formation of TiO2 was characterized by XRD. Morphology of the TiO2 films was observed by using atomic force microscopy (AFM). Optical absorption of the films and degradation concentration of methylene blue had been measured employing UV-Vis spectrophotometer. The hydrophilicity of the thin films was determined in terms of the contact angles of water and NR rubber latex droplets on the coated TiO2 composite films under visible light irradiation. It was found from the experimental study that the TiO2 nano-composite film can improve wet-ability of the coated former surfaces.
Physicochemical and Drug Release Characterization of Lidocaine-Loaded Transdermal Patches Prepared from STR-5L Block Rubber
Wiwat Pichayakorn, Hasleena Boontawee, Wirach Taweepreda, Jirapornchai Suksaeree, Prapaporn Boonme
Industrial & Engineering Chemistry Research · 2014
The aims of this study were to formulate 5% lidocaine-loaded transdermal patches using STR-5L block rubber as a main component of the patch base and to investigate their physicochemical characteristics, in vitro drug release, and stability. The results suggested that STR-5L block rubber could be feasibly used as a main component of the base of pharmaceutical transdermal patches with acceptable physicochemical properties. STR-5L block rubber patches containing lidocaine exhibited lower moisture absorption when compared with the blank counterparts because the drug molecules inserted between the polymer chains. Lidocaine still showed its own crystallinity characteristics after crushing and mixing in STR-5L block rubber patches. Additionally, no chemical interaction between the drug and polymer base was found. The drug-loaded patches could provide drug release with the best fitted to Higuchi square root of time. They had good stability during the studied period of 3 months when kept at 4 °C.
Preparation of Peel-off Mask from Deproteinized Natural Rubber Latex
Wiwat Pichayakorn, Prapaporn Boonme, Wirach Taweepreda
Advanced materials research · 2013
The aim of this research was to develop the peel-off mask in paste form which can be applied to the face and then formed removable thin film. Deproteinized natural rubber latex (DNRL) from Hevea brasiliensis was used as the major film former. After deproteinization by alcalase enzyme treatment, the protein amount was 0.257% that reduced from the initial amount of 1.531%. The appropriate types and amounts of additives were studied by optimization design. The product compatibility and stability were evaluated. The addition of active ingredients for skin nourishing was also investigated. The suitable formulation composed of DNRL, polyvinyl alcohol (PVA) and methylcellulose (MC) as film formers, propylene glycol (PG) and glycerin as plasticizer, Tween 80 as stabilizer, Paraben concentrate as preservative, and other active ingredients including tocopheral acetate, aloe vera, jojoba oil, and tamarind extract. The product was white viscous paste with the pH of 5.69, viscosity of 28,100 cps as pseudoplastic flow behavior, and stable when kept in well-close container at room temperature for more than 1 month. The product in situ film was good elasticity indicated by initial modulus (0.96 MPa), tensile strength (0.208 MPa) and elongation at break (105.6%). Skin irritation in rabbit skin was very slightly which showed the small rash skin but could recover soon. The complacency test in 50 healthy volunteers showed the good results with no irritation effect. In conclusions, DNRL could be prepared peel-off mask product with good properties.
Green Lightweight Concrete Made from Natural Para Rubber Product
Duangden Raksritong, Danupon Tonnayopas, Wirach Taweepreda, Manoon Masniyom
Key engineering materials · 2013
Para Rubber Seed Shell (PRSS) as a coarse aggregate and coated by vulcanization and mixing epoxy natural rubber (ENR) was investigated. Natural rubber latex (60% DRC) was applied in two stages. Firstly stage, synthetic natural latex (ENR-35) solution was coated on the first layer of PRSS. After that, PRSS was coated by vulcanization in second layer. Then, pre-wetting was performed before mixing or casting the concrete for 5 days. Finally, CPRSS (Coated Para Rubber Seed Shell) was produced. The CPRSS aggregate was cast as self consolidation concrete (SCC) with different ratios of ordinary Portland cement: sand: CPRSS for 0.8-1: 0.6-0.85: 0.04-0.12 by weight, respectively and constant water/binder ratio at 0.45 throughtout this study. The ENR-35 was also used about 5% of the water content. However, the concrete was wrapped with polyvinyl sheet to prevent moisture loss during setting and curing in ambient temperature (29°C, 84%RH) for 28 days. The fresh concrete to slump test, harden concrete with bulk density and compressive strength of whole formulations was carried out to determine. The test result A8 indicted that the most ingredient suitable mixture of SCC involed cement: sand: CPRSS of 1:0.94:0.046. The SCC contained the slump as 120 mm, bulk density about 1916 kg/m3 and compressive strength was 37 MPa. Its was met specification of structural lightweight concrete. This beneficiation of SCC is also product as the green innovation building in terms of construction materials and resources, leaving minimal environmental impact, and having energy saving and eco-friendly materials.
Electrospun Epoxidized Natural Rubber with Poly(vinyl chloride) (ENR-PVC) Nanofibrous for PEMFC Applications
Kritsada Phatcharasit, Wirach Taweepreda, Kanoktip Boonkerd, Jin Kuk Kim
Advanced materials research · 2013
Various electrospun epoxized natural rubber / poly (vinyl chloride) (ENR/PVC) blend nonwoven membranes were prepared by electrospinning technique. Various concentration of epoxidized natural rubber (ENR) solution in N,N-dimethylformamide (DMF) were directly added to PVC solution for plasticization of the electrospun nanofibrous. Differencial thermal analysis (DTA), thermogravimetry analysis (TGA), fourier transfrom infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) were used to characterize the pristine and plasticized nanofibrous. DTA results indicated that the addition of ENR resulted in the shifting of glass transition temperature (Tg) towards lower temperatures. The blending of PVC with ENR is thermodynamically incompatible.
Feasibility Studies of Magnesium (II) Removal from Fresh Field Natural Rubber Latex Using Macroporous Cationic Exchange Resin
Sineenart Puangmanee, Wirach Taweepreda
Advanced materials research · 2013
The presence of magnesium ions (Mg2+) in fresh field natural rubber latex (FF-NRL) is a major concern for concentrated production. In general, Mg2+ is reduced by adding diammonia hydrogen orthophosphate (DAP) to FF-NRL. The reaction rate between DAP and Mg2+ in NRL is very slow and is the cause of waste latex sludge, waste time for more than 12 hours, and chemicals loss. Moreover, the waste latex sludge is toxic and has to be treated. In this research, the possibility of using cationic exchange resin to remove Mg2+ from the FF-NRL was investigated. The experiment was carried out by comparison the efficiency of difference commercial exchange resin on Mg2+ reduction rate after immersing in FF-NRL. The results were found that macroporous cationic exchange resin adsorped Mg2+ with highest rate. The Mg2+ content of NRL reduced to 100 ppm after immersing macroporous cationic exchange resin in FF-NRL for 6 hours. The performance of cationic exchange resin was increased after regenerate process with acid and can be used for further to reduce Mg2+ in FF-NRL. The morphology of cationic exchange resin was investigated using scanning electron microscope (SEM).
Deproteinized Natural Rubber as Chewing Gum Base for Nicotine Delivery
Wiwat Pichayakorn, Prapaporn Boonme, Wirach Taweepreda
Advanced materials research · 2013
This study aimed to prepare the nicotine chewing gums for smoking cessation using deproteinized natural rubber latex (DNRL) as gum bases due to its highly flexible property. The formulations were produced by the conventional heat melting and kneading methods. The experimental design was used to obtain the optimum 3 gum base formulations. Each formulation composed of olive oil as a plasticizer; sodium carboxymethylcellulose as an adsorbent; xylitol, mannitol and saccharin sodium as sweeteners instead of sugar. Gum base 1 and gum base 2 had the same sweetener amount but gum base 2 had the lower plasticizer amount, while gum base 1 and gum base 3 had the same plasticizer amount but different sweetener amount. Nicotine was added into each 3 gum bases (NCT1-3). The results showed no significant difference of appearance and taste. Their physicochemical properties were as following: pH of 8.45, 8.46, 8.54, hardness of 39.80, 36.28, 33.14 Shore A, initial modulus of 0.090, 1.260, 0.065 MPa, %elongation of 286, 403, 489%, drug content of 63.62, 70.95, 72.70%, and drug release when 500 times for force clamping of 48.72, 45.72, 67.74%, respectively. After storage at room temperature for 1 month, NCT1 and NCT2 showed unchangeable appearance, but NCT3 showed the slightly liquefied film and much sticky due to hygroscopic property of its sweetener. However, all formulations showed the significant reduction of drug amount which should be further improved in their stability properties.
Fabrication and Characterization of Epoxidized Natural Rubber-Chitosan Membrane
Wirach Taweepreda, Anuchit Wichianchom
Advanced materials research · 2013
The membranes obtained from the mixtures of epoxidized natural rubber latex (ENR) and chitosan solution were prepared and characterized. The chemical structure of the membrane was confirmed by ATR-FT-IR spectroscopy and found the peak at 1315 and 1155 cm-1 indicated ether linkage was formed between epoxide group and chitosan corresponding with an enhancement of their mechanical properties which were observed using dynamic mechanical thermal analysis (DMTA). The dielectric properties and ionic conductivity of membrane were investigated using LCR meter and found that the ionic conductivity was increased with increasing the chitosan content.
Novel Process in Preparation of Deproteinized Natural Rubber Latex
Prapaporn Boonme, Wirach Taweepreda, Wiwat Pichayakorn
Advanced materials research · 2013
Natural rubber latex (NRL) tapped from Hevea brasiliensis is composed of cis-1,4-polyisoprene as the major polymer which provides several desirable physical properties which make it to be interesting in pharmaceutical formulations. However, the International Union of Immunological Societies (IUIS) has reported about latex allergies caused by 14 NRL proteins (Hev b1-14). This problem can be coped with deproteinization of NRL in order to obtain deproteinized natural rubber latex (DNRL). This study aimed to prepare DNRL by novel process which was easy to perform and used pharmaceutical acceptable agents. The obtained DNRL was assayed for remained protein amount in form of nitrogen content by Kjeldahl method. Its physical properties were characterized. Its stability was also physically investigated. The DNRL was tested for the skin irritation in 3 rabbits. It was found that the protein amount of DNRL was 0.257% while the initial protein amount of fresh NRL was 1.531%. Hence, the protein was removed for 83.21%. DNRL had the average pH of 7.27. Both protein content and pH value implied that DNRL should be safe for skin application. DNRL possessed Newtonian flow with low viscosity which should be easy for mixing with other components in the further pharmaceutical formulations. The particle size, polydispersity index (PI), and zeta potential of DNRL were 441.0 nm, 0.240, and -42.53 mV, respectively, indicating narrow size distribution and physical stability. The dry rubber content and total solid content of DNRL were controlled as 39.55% and 40.72%, respectively. The suitable storage condition of DNRL was at 2-8°C in tight containers where DNRL could be kept for longer than 4 months. Very slightly irritation with no allergy caused by DNRL was observed in the tested rabbits. It could be concluded that this deproteinization process was easy and the prepared DNRL by this process was suitable and safe for using in further pharmaceutical and cosmetic formulations.
Improved Deproteinization Process for Protein-Free Natural Rubber Latex
Wiwat Pichayakorn, Jirapornchai Suksaeree, Wirach Taweepreda
Advanced materials research · 2013
Hev b1-14 type proteins in natural rubber latex (NRL) have been identified as allergens in immunogenic responses. Several methods have been developed to reduce these proteins from NRL such as enzyme treatment, centrifugation, creaming, simple or ultrasonic leaching, and chlorination. In this work, the improvement of deproteinization of NRL was developed using the combination of enzyme treatment and leaching processes. The fresh NRL was incubated with 0.2 phr proteolytic alcalase enzyme, and preserved with 2%v/v paraben concentrate in the presence of a 2%v/v sodium lauryl ether sulfate (SLES) as a surfactant at 37°C for 24 hours, and then centrifuged. The upper rubber mass was then leached for three times with either distilled water, a 1%v/v SLES solution, or a mixture of 1%v/v SLES and 2.5%v/v ethanol, and then finally re-dispersed in distilled water. It was found that the increasing process of leaching with either 1%v/v SLES or a mixture of 1%v/v SLES and 2.5%v/v ethanol had the higher efficacy to reduce the remained protein in deproteinized NRL (DNRL). The best deproteinized process was the enzyme treatment and followed by the three times leaching process with a mixture of 1%v/v SLES and 2.5%v/v ethanol, that could completely reduce the proteins in DNRL to 0%. This DNRL had the pH value, viscosity, dry rubber content, and total solid content of 7.41, 13.82 cps, 42.57%, and 44.63%, respectively. Its particle size was 626.23 nm with low polydispersity index of 0.16. The negative charge of SLES could increase the higher negative charge of DNRL to-63.20 mV that exhibited very good physical stability during storage. In conclusions, the combination of enzyme treatment and leaching process with both SLES and ethanol was successful to produce the protein-free DNRL. This DNRL could be further used for several applications including medical skin products.
Cosmetic Pore Packs from Deproteinized Natural Rubber Latex
Wiwat Pichayakorn, Prapaporn Boonme, Wirach Taweepreda
Advanced materials research · 2013
Natural rubber latex (NRL) from Hevea brasiliensis consists of cis-1,4-polyisoprene that have many excellent physical properties such as high elasticity, tensile strength, and easily film-forming. However, some proteins in NRL can cause allergy. Hence, this research aimed to prepare cosmetic pore packs from deproteinized NRL (DNRL) that was prepared in-house by enzyme treatment and centrifugation processes. The properties of DNRL were evaluated in terms of amount of remained protein, pH, particle size, polydispersity index, and zeta potential. This DNRL was then formulated the pore pack products by mixing with the other ingredients and casting to the film form. An appropriate pore pack formulation composed of sodium alginate and polyvinylpyrrolidone K30 mixed with DNRL to produce films with good properties. Hydroxypropylmethylcellulose was also added to another formulation for improving toughness of the films. Both products had similar appearance and physical properties such as thickness, uniformity of weight, pH, tensile strength, and elongation at break, but lower peel strength comparing with the commercial pore pack product. These films showed good flexibility, softness, and toughness. After storage at room temperature for a month, there were no different in appearance and pH that presented good stability. The obtained pore packs also exhibited desirable characteristics with acceptable volunteer satisfactions. However, they should be improved for more adhesiveness in further study. In conclusion, DNRL could be used as major component for cosmetic pore pack preparations.
Preparation and Properties of Electrospun PVC Nanofiber
Kritsada Phatcharasit, Wirach Taweepreda, Kanoktip Boonkerd, Jin Kuk Kim
Advanced materials research · 2013
Nanofibrous membranes based on poly (vinyl chloride) (PVC) were prepared by electrospinning. The morphology of nanofibrous was observed under field emission scanning electron microscope (FE-SEM) and effects of instrument parameters including electric voltage, tip to collector distance, and solution parameters such as PVC concentration and mixed solvent of THF and DMF (50:50) were evaluated. The beads on the fiber were formed with low concentration of PVC. The dielectric constant, thermal properties and crystallinity of the electrospun membranes were characterized by precision LCR meter, and differential thermal analysis (DTA), respectively. It was found that smooth surface of electrospun PVC nanofiber had a high ionic conductivity and their thermal properties were improved comparing with PVC sheet.