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.