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Effect of silk protein fibers on properties of thermoplastic rice starch
(2012-05-01)
Prachayawarakorn, J.
;
Hwansanoet, W.
Biodegradable polymer was prepared as thermoplastic starch (TPS). Due to poor mechanical properties and high water absorption of TPS, thermoplastic rice starch (TPRS) was modified by reinforcing with natural silk protein fibers, as an alternative choice of fiber reinforcement. Different contents and lengths of silk fibers were varied and used as the reinforcement. Internal mixer and compression molding machine were used to mix and shaped the TPRS/silk composites. It was found that stress at maximum load and Young's modulus of the TPRS/silk composites significantly increased with the incorporation of silk fibers. Water absorption of the TPRS/silk composites was also dropped by the addition of silk fibers. Moreover, thermal degradation temperatures of the TPRS/silk composites shifted to higher temperatures by the inclusion of the silk fibers. Functional group analysis and X-ray diffraction patterns were analyzed by FI-IR and XRD techniques, respectively. Furthermore, color measurement, morphology and biodegradation by soil burial test were carried out for different TPRS/silk composites. © 2012 The Korean Fiber Society and Springer Netherlands.
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Effect of Agar and Cotton Fiber on Properties of Thermoplastic Waxy Rice Starch Composites
(2012-03-01)
Prachayawarakorn, J.
;
Limsiriwong, N.
;
Kongjindamunee, R.
;
Surakit, S.
Biodegradable polymer from thermoplastic waxy rice starch (TPWRS) was prepared by internal mixer and compression molding. Since tensile properties and water uptake of the TPWRS was still the main disadvantages, the TPWRS sample was, therefore, modified by agar and/or cotton fibers. The effect of different ratios of agar:cotton fibers on properties of the TPWRS matrix were also studied. It was found that new hydrogen bonds could be found for the TPWRS matrix with the addition of different ratios of agar: cotton fibers by the detection of IR peak shift. Tensile properties of the TPWRS sample were significantly improved by the addition of agar or cotton fibers and the highest tensile properties were obtained from the TPWRS composite modified with 4:6 agar:cotton fibers. In addition, thermal degradation temperature and thermal stability of the starch were improved by the incorporation of agar and/or cotton fibers. Moreover, color measurement, morphology, water uptake and biodegradability from soil burial test were also examined. © 2011 Springer Science+Business Media, LLC.
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Dyeing properties of Bombyx mori silks grafted by 2-hydroxyethyl methacrylate (HEMA)
(2010-10-01)
Prachayawarakorn, J.
;
Khanchaiyapoom, K.
Graft copolymerization technique was selected to improve properties of Bombyx mori silks. The silks were degummed and grafted by 2-hydroxyethyl methacrylate (HEMA), resulting in different graft yields of the degummed silks. It was found that thermal decomposition temperature and wear strength of the silks grafted by HEMA were clearly improved. In addition, dyeing properties of the degummed and HEMA-grafted silks were investigated by using different natural dyes, i. e. coconut shell (Cocos nucifera), pandanus (Pandanus odorus) and Siamese cassia (Cassia siamea) and also synthetic dyestuff, i. e. acid dye. When dyeability and colorfastness properties were investigated, it was observed that higher graft yield of the HEMA-grafted silks exhibited greater dye uptake for all of the applied dyes. Besides, fastness properties to washing, perspiration, light and rubbing of the degummed and HEMA-grafted silks were examined. © 2010 The Korean Fiber Society and Springer Netherlands.
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Properties of thermoplastic rice starch composites reinforced by cotton fiber or low-density polyethylene
(2010-06-11)
Prachayawarakorn, J.
;
Sangnitidej, P.
;
Boonpasith, P.
Biodegradable polymer was prepared from thermoplastic rice starch (TPRS) plasticized by glycerol. In order to improve poor tensile properties and high water absorption of the TPRS, cotton fiber or low-density polyethylene (LDPE) were added into the TPRS matrix. The effect of maleic anhydride-grafted-polyethylene (MAPE) and vinyltrimethoxy silane (VTMS) compatibilizers on properties of the TPRS/LDPE specimens were also studied. The TPRS/cotton fiber, TPRS/LDPE, TPRS/LDPE/MAPE and TPRS/LDPE/VTMS samples were analyzed for tensile and morphological properties. The results showed that the incorporation of either cotton fiber or LDPE into the TPRS matrix caused the considerable improvement of tensile strength and Young's modulus. Moreover, water absorption of the TPRS samples was clearly reduced by the inclusion of cotton fiber or LDPE. In addition, phase morphology, thermal stability and biodegradability were carried out for different TPRS samples. Crown Copyright © 2010.
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Effects of silane and MAPE coupling agents on the properties and interfacial adhesion of wood-filled PVC/LDPE blend
(2008-06-15)
Prachayawarakorn, J.
;
Khunsumled, S.
;
Thongpin, C.
;
Kositchaiyong, A.
;
Sombatsompop, N.
Composite samples were prepared from Poly(vinyl chloride)/low-density polyethylene (PVC/ LDPE) blend, compatibilized by PA20 (methyl methacrylate-co-butyl acrylate copolymer), and reinforced by different levels of rubber-wood sawdust. To improve the mechanical properties of the composites, Silane A-137 (Octyltriethoxy silane), Silane A-1100 (γ- aminopropyltriethoxy silane), or MAPE (maleic anhydride-grafted-polyethylene) were introduced. It was found that the additions of Silane A-137, Silane A-1100, and MAPE could improve tensile and impact properties of the composites, regardless of the sawdust contents. Physical or chemical interactions for all coupling agents with the wood-PVC/LDPE composites used were proposed in this work. Silane A-137 or MAPE tended to give better improvement in the mechanicalproperties of the composites than Silane A-1100, because of the presence of the nonpolar chain ends of Silane A-137 or MAPE molecules. Besides, the addition of either Silane A-137 and MAPE or Silane A-1100 and MAPE at different ratios into the wood-PVC/LDPE composites was also studied. The experimental results suggested that the optimum mechanical properties could be obtained using Silane A-137 : MAPE of 1% : 2% wt sawdust. The morphological and thermal properties of the composites were also examined using SEM and DMA techniques, respectively. © 2008 Wiley Periodicals, Inc.
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Physical, chemical, and dyeing properties of Bombyx mori silks grafted by 2-hydroxyethyl methacrylate and methyl methacrylate
(2007-11-05)
Prachayawarakorn, J.
;
Boonsawat, K.
To obtain silk weight gain and to improve silk properties, Bombyx mori silks were grafted with either 2-hydroxyethyl methacrylate (HEMA) or methyl methacrylate (MMA). The moisture regain of the HEMA-grafted and MMA-grafted silks depended on the hydrophilicity of the used monomers. The acid and alkaline resistances of the HEMA-grafted and MMA-grafted silks were clearly improved. Both commercial synthetic dyes, that is, acid and reactive dyes, and a natural dye extracted from turmeric, with potassium aluminum sulfate as a mordant, were used in this study. The results suggested that the dye uptake increased in the presence of poly(2-hydroxyethyl methacrylate) or poly(methyl methacrylate) in the silk fibroin structures when acid and curcumin dyes were used. The washfastness level of the HEMA-grafted silk dyed by acid and reactive dyes was similar to that of the degummed silk. However, the colorfastness to washing of the MMA-grafted silk dyed by an acid dye was improved when the polymer add-on concentration was 65%. In addition, the washfastness for both grafted silks was improved when they were dyed with natural curcumin dyestuff. The acid and alkaline perspiration fastness properties remained unchanged for the HEMA-grafted and MMA-grafted silks when acid, reactive, and curcumin dyes were applied. © 2007 Wiley Periodicals, Inc.
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Effects of compatibilizer type and rubber-wood sawdust content on the mechanical, morphological, and thermal properties of PVC/LDPE blend
(2006-10-05)
Prachayawarakorn, J.
;
Khamsri, J.
;
Chaochanchaikul, K.
;
Sombatsompop, N.
This article aimed to investigate the mechanical, morphological and thermal properties of PVC/LDPE blend with and without the addition of compatibilizers. The effects of LDPE content, compatibilizer type and rubberwood sawdust loading on the properties of the blend were evaluated. The experimental results suggested that as the LDPE content was increased the mechanical properties of PVC-LDPE blend progressively decreased due to poor interfacial adhesion. The continuity and compatibility between PVC and LDPE phases could be improved through three different types of compatibilizers which included chlorinated polyethylene (CPE) poly(methyl-methacrylate-co-butyl acrylate) (PA20) and poly(ethylene-co-methacrylate) (Elvaloy). The PA20 was found to be the most suitable compatibilizer for the blend. A radical transfer reaction was proposed in this work to explain the structure and thermal changes of the PVC in PVC-LDPE blend. The decomposition temperature of PVC in the blend decreased with the loading of the PA20 and the wood sawdust. As the sawdust content was increased the tensile and flexural moduli increased with considerable decreased in the tensile, flexural and impact strength, a slight improvement being achieved if the PA20 was incorporated in the composite. © 2006 Wiley Periodicals, Inc.

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