KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 5 of 5

Some of the metrics are blocked by your
consent settings
Toughening Polylactide Stereocomplex by Injection Molding with Thermoplastic Starch and Chain Extender
(2023-05-01)
Srithep, Yottha
;
Pholharn, Dutchanee
;
Worajittiphon, Patnarin
;
Sriprateep, Keartisak
;
Veang-in, Onpreeya
The high cost, low heat resistance, and brittleness of poly(L-lactide) (PLLA) is a significant drawback that inhibits its diffusion into many industrial applications. These weaknesses were solved by forming a polylactide stereocomplex (ST) and blending it with thermoplastic starch (TPS). We blended poly (L-lactide)(PLLA), up to 30% thermoplastic starch, and a chain extender (2%) in an internal mixer, which was then hand-mixed with poly (D-lactide)(PDLA) and injection molded to form specimens, in order to study mechanical, thermal, and crystallization behavior. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (XRD) demonstrated that the stereocomplex structures were still formed despite the added TPS and showed melting points ~55 °C higher than neat PLLA. Furthermore, stereocomplex crystallinity decreased with the increased TPS content. Dynamic mechanical analysis revealed that ST improved PLLA heat resistance, and tensile testing suggested that the TPS improved the elongation-at-break of ST. Moreover, the chain extender reduced the degradation of ST/TPS blends and generally improved ST/TPS composites’ mechanical properties.
Some of the metrics are blocked by your
consent settings
Effects of Hydroxypropyl Methylcellulose Fiber Amounts and Aspect Ratios on Properties of Biodegradable Composites Prepared from Thermoplastic Starch
(2023-01-01)
Pitpisutkul, Vipawan
;
Jamjumras, Trisana
;
Sawasdee, Kancharut
;
Prachayawarakorn, Jutarat
Because of the low tensile properties and high hydrophilicity of thermoplastic starch (TPS), this research was focused on improving its characteristics through the addition of the natural cellulose fiber, hydroxypropyl methylcellulose (HPMC). Different TPS composites reinforced with HPMC fibers were compounded using an internal mixer and were shaped using a compression molding machine. The effects of HPMC fiber content and aspect ratios were examined. It was found from infrared spectra that the wavenumbers of the O-H stretching of TPS polymer clearly shifted to lower wavenumber with the incorporation of HPMC fibers, which indicated new hydrogen bond formation. Moreover, a significant increase of maximum stress and elastic modulus of TPS/ HPMC fiber composites was detected. A clear drop in moisture uptake was also found when HPMC fibers were added into the TPS polymer matrix. In addition, scanning electron microscopy and thermogravimetric analysis were used to characterize several TPS composites. Biodegradability for various composites was also determined.
Some of the metrics are blocked by your
consent settings
Characterization and Properties of Biodegradable Thermoplastic Arrowroot Starch Crosslinked by Glutaraldehyde Processed by Compression Molding Technique
(2022-09-01)
Prachayawarakorn, Jutarat
;
Suthichujit, Autjima
Although starch is available and biodegradable, hydrophilicity and mechanical properties are still main disadvantages for many applications. In this study, arrowroot starch, a perennial herb found in tropical climates and extracted from the tubers of the arrowroot plant was used. The arrowroot starch was chemically modified by crosslinking with different amounts of glutaraldehyde in order to overcome the starch disadvantages. The crosslinked starch was then prepared as thermoplastic starch by plasticizing with glycerol, compounding in an internal mixer and finally shaping in a compression molding machine. An increase of gel fraction and decrease of swelling as well as the moisture uptake of different thermoplastic crosslinked arrowroot starch samples were observed, all of which indicated a crosslinking reaction of glutaraldehyde with the starch molecules. The thermal degradation temperature of thermoplastic crosslinked arrowroot starch, determined from thermogravimetric analysis technique, increased when compared with thermoplastic arrowroot starch. The extensibility of the thermoplastic crosslinked arrowroot starch also improved via glutaraldehyde crosslinking. Higher content of glutaraldehyde also caused lower swelling and moisture uptake including higher gel fraction and extensibility. Moreover, crystallinity, morphology and biodegradability were also examined.
Some of the metrics are blocked by your
consent settings
Active Thermoplastic Starch Film with Watermelon Rind Extract for Future Biodegradable Food Packaging
(2022-08-01)
Todhanakasem, Tatsaporn
;
Jaiprayat, Chayanit
;
Sroysuwan, Thunchanok
;
Suksermsakul, Supakanya
;
Suwapanich, Rachit
Petrochemical plastic wastes generate serious environmental problems because they are resistant to natural decomposition. The aim of this study was to develop a biodegradable active thermoplastic film composed of polyvinyl alcohol (PVA), corn starch (ST), glycerol, and the active compounds from watermelon rind extract (WMRE), or PVA/ST/WMRE, using the casting technique. The film was examined for its mechanical, antioxidant, and functional properties against selected foodborne pathogens. The results showed that the addition of 10% v/v of watermelon rind extract to the film formulation significantly increased the tensile strength from 19.44 ± 0.84 MPa to 33.67 ± 4.38 MPa and slightly increased the percent elongation at break (% EAB) from 35.04 ± 0.96% to 35.16 ± 1.08%. The antioxidant property of PVA/ST/WMRE film was analyzed based on the DPPH scavenging activity assay, which significantly increased from 29.21 ± 0.24% to 63.37 ± 4.27%. The minimum inhibitory concentration (MIC) of watermelon rind extract was analyzed for the growth inhibition of Bacillus cereus ATCC 11778, Escherichia coli ATCC 8739, and Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311, with 10% (v/v) found as an optimal concentration against B. cereus. Wrapping fresh-cut purple cabbage with PVA/ST/WMRE film significantly reduced the microbial load after 3 days of storage, in comparison to commercial packaging (PET) and thermoplastic control film. Consumer testing of the packaging film indicated that user acceptance of the product was favorable. Therefore, we suggest that this newly developed film can be used as a biodegradable food packaging item that will lead to enhanced food safety, food quality, prolonged shelf life, and consumer acceptance for further food applications.
Some of the metrics are blocked by your
consent settings
Effects of Polymethacrylamide-Grafted Branch on Mechanical Performances, Hydrophilicity, and Biodegradability of Thermoplastic Starch Film
(2019-11-01)
Weerapoprasit, Chayapa
;
Prachayawarakorn, Jutarat
To overcome the shortcomings of brittleness and high water uptake of thermoplastic native starch (TPNS) film, thermoplastic-grafted starch (TPGS) film is prepared and tested using starch-g-polymethacrylamide (PMAM) with different percentages of grafting. Starch-g-PMAM is compounded in an internal mixer and then shaped by a compression molding machine to produce a TPGS film. Functional group analysis by Fourier transform infrared spectroscopy (FTIR) revealed that the graft copolymerization is successful, as evident from new characteristic infrared (IR) peaks of amide group (C═O stretching and N─H bending). TPGS films with MAM has more surface roughness than TPNS film does. With higher grafting percentages, the degrees of crystallinity and hydrophilicity of TPGS film reduce while the extensibility (based on strain at maximum load) and surface roughness increase, compared to that at lower percentages of grafting. The biodegradability of TPGS films grafted with MAM at different percentages is also examined.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results