physics by Yupaporn Ruksakulpiwat
Glycidyl methacrylate (GMA) was grafted onto poly (lactic acid) (PLA) by melt mixing in internal ... more Glycidyl methacrylate (GMA) was grafted onto poly (lactic acid) (PLA) by melt mixing in internal mixer using dicumyl peroxide (DCP) as an initiator. The results from proton nuclear magnetic resonance (1H-NMR) and Fourier transform infrared (FTIR) spectroscopy indicated that the grafting reaction of GMA onto PLA took place successfully. The impact strength of PLA-g-GMA was significantly higher than that of pure PLA. The crystallinity of PLA, obtained from differential scanning calorimetry (DSC), decreased after grafting. In order to obtain the optimal mixing conditions, the mixing time was varied into 7, 10 and 14 min. The optimum mixing time of 10 min was found to give the optimum mechanical properties of glycidyl methacrylate grafted poly (lactic acid) (PLA-g- GMA). However, the mixing time played no important role in impact behavior of PLA-g-GMA. In addition, the highest crystallinity was obtained with the PLA-g-GMA prepared with the mixing time of 7 min.
Papers by Yupaporn Ruksakulpiwat
Polymers
This study illustrated the potential applications of thermoresponsive poly(N-isopropylacrylamide)... more This study illustrated the potential applications of thermoresponsive poly(N-isopropylacrylamide) (PNIPAm) grafted nylon membranes with different grafting yields and grafting architecture. The thermoresponsive gating performance at temperatures below and above the lower critical solution temperature (LCST) of PNIPAm (32 °C) were demonstrated. The linear PNIPAm-grafted nylon membrane exhibited a sharp response over the temperature range 20–40 °C. The grafting yield of 25.5% and 21.9%, for linear and crosslinked PNIPAm respectively, exhibited highest thermoresponsive gating function for water flux and had a stable and repeatable “open-closed” switching function over 5 cycle operations. An excellent oil/water separation was obtained at T < 32 °C, at which the hydrophilic behavior was observed. The linear PNIPAm-grafted nylon membrane with 35% grafting yield had the highest separation efficiency of 99.7%, while PNIPAm structures were found to be independent of the separation efficien...
Materials Today: Proceedings, 2021
Molecular weight (MW) is an important factor that affects mechanical properties of polymeric mate... more Molecular weight (MW) is an important factor that affects mechanical properties of polymeric material. The positive relationship between molecular weight and mechanical properties of polymeric fibers can be ascribed to an increase in the length of the molecular chains. In this research, effect of Polylactic acid (PLA) molecular weight on morphological and mechanical properties of electrospun PLA were studied. PLA with two different molecular weights were used to prepare some samples by using electrospinning process at various concentrations (10%, 15% and 20% w/v). The condition for fabricating electrospun PLA was a 15 cm of collection distance and 15 kV of working voltage. Morphology of the electrospun PLA was studied by the field emission scanning electron microscope (FE-SEM). Mechanical properties including tensile strength, Young's modulus and elongation at break were determined by using the universal testing machine. The obtained suitable sample with optimum mechanical properties will be used in further step for the meniscus tissue engineering scaffold. The result of the study reported, the 20% low molecular weight electrospun (PLAL-20%H) fibers has the highest tensile strength (2.83 ± 0.47 MPa) and Young's modulus (160.67 ± 34.06 MPa) while 20% the high molecular weight electrospun (PLAH-20%) fibers has the highest elongation at break (25.87 ± 6.47%). In fact, the uniform and smooth surface fibers was observed in high relative humidity (RH) condition during electrospining process. In conclusion, higher mechanical properties of electrospun PLA nanofiber were obtained from a higher concentration.
Polymers
Nano−hydroxyapatite (nHAp) as a bio−filler used in PLA composites was prepared from fish by acid ... more Nano−hydroxyapatite (nHAp) as a bio−filler used in PLA composites was prepared from fish by acid deproteinization (1DP) and a combination of acid−alkali deproteinization (2DP) followed by alkali heat treatment. Moreover, the PLA/nHAp composite films were developed using solution casting method. The mechanical and thermal properties of the PLA composite films with nHAp from different steps deproteinization and contents were compared. The physical properties analysis confirmed that the nHAp can be prepared from fish scales using both steps deproteinization. 1DP−nHAp showed higher surface area and lower crystallinity than 2DP−nHAp. This gave advantage of 1DP−nHAp for use as filler. PLA composite with 1DP−nHAp gave tensile strength of 66.41 ± 3.63 MPa and Young’s modulus of 2.65 ± 0.05 GPa which were higher than 2DP−nHAp at the same content. The addition of 5 phr 1DP−nHAp into PLA significantly improved the tensile strength and Young’s modulus. PLA composite solution with 1DP−nHAp at 5 ...
Polymers
Biopolymer based scaffolds are commonly considered as suitable materials for medical application.... more Biopolymer based scaffolds are commonly considered as suitable materials for medical application. Poly(lactic acid) (PLA) is one of the most popular polymers that has been used as a bioscaffold, but it has poor cell adhesion and slowly degrades in an in vitro environment. In this study, silk fibroin (SF) was selected to improve cell adhesion and degradability of electrospun PLA. In order to fabricate a PLA/SF scaffold that offered both biological and mechanical properties, related parameters such as solution viscosity and SF content were studied. By varying the concentration and molecular weight of PLA, the solution viscosity significantly changed. The effect of solution viscosity on the fiber forming ability and fiber morphology was elucidated. In addition, commercial (l-lactide, d-lactide PLA) and medical grade PLA (pure PLLA) were both investigated. Mechanical properties, thermal properties, biodegradability, wettability, cell viability, and gene expression of electrospun PLA and...
Polymer Bulletin, 2020
Triblock copolymers of poly(lactic acid) (PLA) and natural rubber (NR) (PLA-NR-PLA) with differen... more Triblock copolymers of poly(lactic acid) (PLA) and natural rubber (NR) (PLA-NR-PLA) with different lengths of PLA end blocks were produced from hydroxyl-terminated liquid natural rubber (HTLNR) and low molecular weight PLA (pre-PLA). The HTLNR with a number-average molecular weight (M n) ~ 28,000 g/mol obtained from photochemical degradation of NR and pre-PLA with varying molecular weight (M n ~ 3000, ~ 6500, ~ 9700 g/mol) was subjected to condensation polymerization. The compatibilizing effect of copolymers on the physical properties of the PLA/NR blend was studied using PLA/NR/PLA-NR-PLA blend ratios of 90/10/0, 90/9/1, 90/8/2 and 90/7/3 percent by weight (wt%). From the tensile testing results, elongation at break of the blends increased with an increase in the amount of triblock copolymer and with the length of the PLA end block. The blend without the copolymer showed elongation at break of 60.54%, whereas the blend with 3 wt% of PLA-NR-PLA prepared from pre-PLA with M n of ~ 9700 g/mol showed elongation at break of 199.38%. This was about a 300% increase. The highest impact strength of 79.58 kJ/m 2 (400% higher than neat PLA) was also found for the blend containing 3 wt% of PLA-NR-PLA with the longest PLA end block. A reduction in the diameter and well dispersion of the rubber particles in the PLA matrix were seen in micrographs taken with a scanning electron microscope. In general, after the addition of PLA-NR-PLA into a PLA/NR blend, the T g of NR phase shifted to a higher temperature, whereas the T g of the PLA phase decreased. The PLA-NR-PLA triblock copolymer with the longest PLA end block is possibly used as an effective compatibilizer for the PLA/NR blend.
Journal of Physics: Conference Series, 2022
Natural rubber (NR) is a renewable resource that is used in many products. In the production of N... more Natural rubber (NR) is a renewable resource that is used in many products. In the production of NR products, other rubbers or fillers may be used to produce a product with required properties. However, most rubbers and fillers are synthetic which are non-environmentally friendly materials. To solve this problem, rice husk ash (RHA) from biomass power plant was used to prepare silica to be used as a filler in rubber by in-situ generation. The purer RHA was prepared by leaching with HCl to remove some metallics and increase silica contents by combustion. The purer RHA was dissolved in NaOH to obtain sodium silicate from RHA (RSS). Carboxylated styrene-butadiene rubber (XSBR) used as synthetic rubber was blended with NR in latex form. NR/XSBR at the ratio of 2:1 was mixed with RSS to obtain NR/XSBR/RSS mixture. Acetic acid was dropped into the mixture until neutral for precipitating silica to obtain NR/XSBR/RSi composite. The mechanical, morphological, and thermal properties of NR/XSBR...
Advanced Materials Research, 2011
In this work, the effect of heat treatment on chemical and crystalline structure of vetiver powde... more In this work, the effect of heat treatment on chemical and crystalline structure of vetiver powder was studied. The vetiver powder was heat treated at 170°C, the temperature below thermal decomposition of hemicellulose, for 2-6 hours. The chemical structure, crystalline structure, and thermal decomposition of untreated and heat-treated vetiver were examined via FTIR spectrometer X-ray diffractometer, and thermogravimetric analyzer, respectively. In addition, the particle size and size distribution, fiber surface, and specific surface area were investigated by particle size analyzer, scanning electron microscope, and BET surface analyzer, repectively. It was founded that some waxes, lignin, and hemicellulose were removed by the thermal treatment. This resulted in smaller particle size of heat-treated vetivers. In addition, moisture content was minimized from 7 to 4 wt% by the treatment. However, removal of those compositions did not influence crystal structure of cellulose and surfac...
Journal of Physics: Conference Series, 2022
This study aims to produce composite nanofibers from polylactic acid (PLA) and silk fibroin (SF) ... more This study aims to produce composite nanofibers from polylactic acid (PLA) and silk fibroin (SF) with mechanical properties similar to that of a native meniscus. SF is a natural protein, well known for its good biocompatibility and biodegradability but it has poor mechanical properties compared to synthetic polymers. SF contains proteins which can promote cell adhesion and cell proliferation required for a tissue engineering scaffold. PLA is a popular material that is widely used in tissue engineering. It provides high mechanical properties but lacks bioactivity and cell affinity. Thus, a PLA/SF composite scaffold can improve these drawbacks. In this study, PLA/SF nanofibers were fabricated using an electrospinning process at various PLA and SF ratios (PLA: SF 100:0, 75:25, 50:50, and 25:75). The SF content in the emulsion dominated the fiber diameter, fiber arrangement and processibility of nanofibrous scaffold. With increasing SF content, the %elongation at break of PLA/SF scaffol...
This research studied the preparation of grafting vinyltrimethoxysilane ( VTMS )onto natural rubb... more This research studied the preparation of grafting vinyltrimethoxysilane ( VTMS )onto natural rubber(NR )in a latex system using cumene hydroperoxide ( CHP )and tetraethylene pentamine (TEPA )as redox couple initiators . Effects of monomer content and grafting temperature on grafting efficiency and percentages of grafting %(GP )were investigated .The results showed that the highest grafting efficiency and percentages of grafting was obtained at the reaction temperature of 40C and the amount of monomer was 10 phr .The grafted NR was characterized by Attenuated total reflection fourier transform infrared spectrophotometer (ATR – FTIR.) The spectra showed absorption peaks of –Si-O-C at 1126 cm and -Si-O-Si -at 1040 cm .These peaks indicate the siloxane linkage of copolymer obtained from the grafting reaction between NR and VTMS .Morphology of copolymer was observed by transmission electron microscopy (TEM.) Effect of monomer content on mechanical properties of copolymer was investigated...
Materials Today: Proceedings, 2021
Silk fibroin (SF) and polyvinyl alcohol (PVA) are biopolymers which possess the biocompatibility,... more Silk fibroin (SF) and polyvinyl alcohol (PVA) are biopolymers which possess the biocompatibility, biodegradability and non-toxicity. Theses biopolymers are feasible to fabricate as a nanofiber, which is similar to collagen fiber of native meniscus. Therefore, electrospinning using SF blended PVA has been investigated in this study. One important factor affecting electrospinning process is the humidity. The influence of humidity on the formation and the physical properties of nanofiber was therefore studied. Silk fibroin blended with polyvinyl alcohol was prepared with 1:3 ratio in different humidity. The morphology of the SF/PVA blended electrospun nanofiber was examined using a field emission scanning electron microscope (FE-SEM). Mechanical properties were also tested using a universal testing machine. The result of this study showed fiber diameter size of SF/PVA electrospun nanofiber in range of 111 ± 29 to 90 ± 33 nm, it decreased when relative humidity increased. Tensile strength was slightly decreased while %elongation at break was slightly increased with increasing humidity.
In this research, vetiver grass-polypropylene (PP) composites were prepared by using an injection... more In this research, vetiver grass-polypropylene (PP) composites were prepared by using an injection molding. The characterization of vetiver grass was investigated. The effect of vetiver particle sizes on the rheological, thermal, and mechanical properties of the composites were determined. In addition, the effects of vetiver particle sizes, and vetiver contents on shear-induced crystallization layer, degree of crystallinity, and crystallinity distribution were elucidated. The crystallization kinetics and spherulitic growth rate were also analyzed.
Advanced Materials Research, 2013
In this research work, the effect of compatibilizers on mechanical and thermal properties of ESP/... more In this research work, the effect of compatibilizers on mechanical and thermal properties of ESP/HDPE composites was investigated. High density polyethylene grafted with maleic anhydride (HDPE-g-MA) and ethylene propylene rubber grafted with maleic anhydride (EPR-g-MA) were used to compatibilize the ESP/HDPE composites. The ESP/HDPE composite with and without the compatibilizes was prepared at 20 wt.% ESP. The volume average particle size of ESP was 20.35 µm. The compatibilized HDPE composites were prepared at 2, 5, 8 and 10 wt.% of HDPE-g-MA and at 2, 5, 8 and 10 wt.% of EPR-g-MA, as well. It was found that ultimate stress, yield strength, and elongation at break of the ESP/HDPE composites prepared with HDPE-g-MA increased with increasing HDPE-g-MA content. In addition, Young’s modulus was maximum at 8 wt.% HDPE-g-MA. The composites filled with HDPE-g-MA had improved impact strength with increasing HDPE-g-MA content. On the other hand, the composites with EPR-g-MA showed a decrease...
Polymer-Plastics Technology and Engineering, 2013
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physics by Yupaporn Ruksakulpiwat
Papers by Yupaporn Ruksakulpiwat