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Articles by Yaowalak Srisuwan
Total Records ( 4 ) for Yaowalak Srisuwan
  Yodthong Baimark , Yaowalak Srisuwan , Nuanchai Kotsaeng and Theeraphol Phromsopha
  Methoxy poly(ethylene glycol)-b-poly(ε-caprolactone-co-D,L-lactide) diblock copolymers [MPEG-b-P(CL-co-DLL)] were synthesized by ring-opening polymerization of CL and DLL using MPEG with molecular weight of 5,000 g mol-1 and stannous octoate as the initiating system. Surfactant-free and core-shell nanoparticles of MPEG-b-P(CL-co-DLL) were prepared by modified-spontaneous emulsification solvent diffusion method without any surfactants. Influences of CL:DLL ratio of the diblock copolymers on nanoparticle characteristics were investigated and discussed. The sizes of colloidal nanoparticles obtained from light-scattering analysis were in the range of 84-639 nm. The nanoparticle size decreased with increasing the DLL ratio. Scanning and transmission electron micrographs indicated that the nanoparticles were spherical in shape and smooth surface. Core-shell structure of the nanoparticles consisting of the hydrophilic outer shell of MPEG and the hydrophobic inner core of P(CL-co-DLL) was confirmed by 1H-NMR spectroscopy.
  Yodthong Baimark and Yaowalak Srisuwan
  Background and Objective: Bio-renewable and biodegradable stereo complex polylactides (scPLs) have widely investigated for use as high-performance bioplastic products. However, melt process ability and brittleness of the scPL were limited for this purpose. In this study, physicochemical and mechanical properties of scPL/poly(ε-caprolactone-co-L-lactide) copolyester blends with and without chain extension were determined. Materials and Methods: The scPL/copolyester blend pellets were prepared by in situ melt blending of poly(L-lactide), poly(D-lactide) and copolyester. The influences of the copolyester ratios (100/0, 90/10, 80/20 and 60/40 w/w) and chain extension on the characteristics of the scPL pellets, including stereo complex formation, thermal stability, melt flow index (MFI) and their film forming were determined. Properties of the compressed blend films were also investigated. Results: The copolyester blending enhanced the stereo complexation of the blend pellets. The MFI of the blend pellets increased with the copolyester ratio. The continuous and smooth blend films were successfully prepared using a compression molding technique when the copolyester ratio was increased up to 20% wt. The compression force also enhanced the stereo complexation of the blend films. The chain extension improved the phase compatibility of the scPL/copolyester blend films. The flexibility of the blend films slightly improved as the copolyester ratio increased. Conclusion: This study could provide a new insight into the synergistic effects of copolyester blending, chain extension and compression force for designing high-performance scPL products with controllable film forming and flexibility.
  Yaowalak Srisuwan , Mangkorn Srisa-ard , Chaiyasit Sittiwet , Yodthong Baimark , Nual- Anong Narkkong and Chirapha Butiman
  Nanocomposite and nanoporous silk fibroin (SF) films were prepared by film casting of SF solution containing surfactant-free colloidal nanoparticles of methoxy poly (ethylene glycol)-b-poly (D, L-lactide) diblock copolymer (MPEG-b-PDLL). Self-condensation and nanophase separation of the nanoparticles from SF film matrix during film drying process gave nanopore structures. The colloidal nanoparticles were prepared in SF solution by modified-spontaneous emulsification solvent diffusion method without any surfactant. The interaction between SF and MPEG-b-PDLL in nanocomposite films was studied by Fourier transform infrared spectroscopy and thermogravimetry. The film transparency of SF nanocomposite films decreased as increasing the MPEG-b-PDLL ratio. Scanning Electron Microscopy (SEM) results indicated that the nanoparticle sizes in the films were in the range of 50-200 nm with spherical shape. Nanopore structures with pore size of less than 150 nm can be observed from SEM images of the film surface and cross-section. The nanopores are interconnected throughout the nanocomposite films. The number and size of nanoparticles and nanopores increased when the MPEG-b-PDLL ratio was increased.
  Yodthong Baimark and Yaowalak Srisuwan
  Poly(L-lactide) (PLL) is an environmentally friendly polymer that has widely been used in medical and packaging applications because of its biodegradability and biocompatibility. Star-shaped PLLs are expected to exhibit different properties compared to the linear PLL. The objective of this study was to investigate the effects of blend ratios and blending techniques including single step ring-opening polymerization and solution blending on the characteristics of linear (1-arm)/star-shaped (6-arm) PLL blends. A 1-dodecanol/ dipentaerythritol mixture and stannous octoate were used as an initiating system. Intrinsic viscosity, glass transition temperature and crystallizing temperature of the PLL blends steadily increased, while heat of crystallization and heat of melting significantly decreased when the star-shaped blend ratio was increased. However, melting temperature and thermal decomposition did not change. Mechanical properties of the PLL films were also influenced by the blend ratio. The physical and mechanical properties of the PLL blends obtained from single step polymerization depend upon the blend ratio, similar as when they are obtained from the solution blending method.
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