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    Modification of biodegradable thermoplastic cassava starch/kapok fiber incorporated by tartaric acid and processed by compression molding technique
    (2024-01-01)
    Panjapornpattana, Kanisara
    ;
    Sareethao, Supapich
    ;
    Thermoplastic starch has been attracted due to its availability, biodegradability, and processability. However, its poor tensile properties, high hydrophilicity and lack of antibacterial activity are still the major concerns for many applications. In current study, several thermoplastic cassava starch samples (THPCS), reinforced with kapok (KP) fibers and modified by varying levels of tartaric acid (TA), a natural organic acid, were prepared to enhance their limitations. All samples were mixed and shaped using an internal mixer and a compression molding machine, respectively. The modified THPCS samples were characterized using analytical techniques such as FTIR, SEM and TGA. Morphology, water uptake, mechanical properties, biodegradability, and antimicrobial performance of various samples were also evaluated. IR peak positions of O–H stretching as well as O–H bending were clearly observed for shifting to lower wavenumbers with the addition of KP fibers or KP fibers/TA, indicating of new H-bond formation. In addition, the use of KP fibers caused the enhancement of mechanical strength and thermal properties including the reduction of water uptake. Moreover, THPCS/KP fiber sample modified by TA presented surface smoothness, good biodegradability, and antibacterial performance against both Staphylococcus aureus and Escherichia coli.
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    Effect of carrageenan on properties of biodegradable thermoplastic cassava starch/low-density polyethylene composites reinforced by cotton fibers
    (2014-01-01) ;
    Pomdage, Wanida
    Applications of biodegradable thermoplastic starch (TPS) have been restricted due to its poor mechanical properties, limited processability and high water uptake. In order to improve properties and processability, thermoplastic cassava starch (TPCS) was compounded with low-density polyethylene (LDPE). The TPCS/LDPE blend was, then, modified by a natural gelling agent, i.e. carrageenan and natural fibers, i.e. cotton fibers. All composites were compounded and processed using an internal mixer and an injection molding machine, respectively. It was found that stress at maximum load and Young's modulus of the TPCS/LDPE composites significantly increased by the addition of the carrageenan and/or the cotton fibers. The highest mechanical properties were obtained from the TPCS/LDPE composites modified by both the carrageenan and the cotton fibers. Percentage water absorption of all of the TPCS/LDPE composites was found to be similar. All modified composites were also degraded easier than the non-modified one. Furthermore, all the composites were analyzed using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning electron microscopy (SEM). © 2014 Elsevier Ltd.
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    Asymmetric dot-patterned wettable and antibacterial wound dressings from bacterial cellulose–alginate composites coated with stearic acid-modified ZnO/chitosan/AgNPs
    (2025-01-01)
    Ieamviteevanich, Pimchanok
    ;
    Onklam, Panida
    ;
    Kampechdee, Wariya
    ;
    Churiwan, Achana
    ;
    To improve the wound dressing characteristics of bacterial cellulose-based materials and address the issue of asymmetric wound dressing with one hydrophilic side and another hydrophobic side, this study developed a new concept for the fabrication of an asymmetric wettable and antibacterial wound dressing by selective drop coating of stearic acid-modified ZnO, chitosan, and AgNPs to form a dot pattern on both surfaces of a bacterial cellulose–alginate composite (BA-ZnS/Ch/Ag). The coated surface was hydrophobic, with a WCA of 150° due to the formation of a low surface energy zinc stearate (C<inf>17</inf>H<inf>35</inf>COO)<inf>2</inf>Zn) monolayer on the ZnO particles and a high degree of hierarchical roughness. The asymmetric wettable BA-ZnS/Ch/Ag wound dressing maintained good water absorptivity (swelling rate 417%) and natural breathability (water vapor transmission rate 792 g.m<sup>−2</sup> day<sup>−1</sup>) of the superhydrophilic bacterial cellulose-alginate composite that consisted of dense outer surfaces and porous inner layers and simultaneously possessed the superhydrophobic property of the coating area that can reduce the risk of infection from external fluids and improve the blood repellency and anti-adhesion properties. The BA-ZnS/Ch/Ag wound dressing showed good antibacterial activity against S. aureus and E. coli and non-toxicity to human keratinocyte immortal cells (HaCaT), making it suitable for clinical applications.
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    Effect of neem wood sawdust content on properties of biodegradable thermoplastic acetylated cassava starch/neem wood sawdust composites
    (2017-03-01) ;
    Hanchana, Areeya
    Due to several important limitations for applications of thermoplastic starch (TPS), thermoplastic acetylated cassava starch (TPACS) polymer was reinforced by different contents of neem wood sawdust (SD). Thermoplastic cassava starch (TPCS)/SD composites were also prepared and reinforced by different SD contents and compared with the TPACS/SD composites. Morphological, thermal, and biodegradable properties of different composites were also examined. The results showed that IR absorption bands of OH stretching and OH bending vibrations shifted to lower wavenumbers, indicating new hydrogen bond formation for all composites. Stress at maximum load and Young's modulus were significantly improved when the SD content increased for all the TPACS/SD and TPCS/SD composites; strain at maximum load was higher for the TPACS/SD composites. A decrease in water uptake was detected when the SD reinforcement was incorporated into either the TPACS or TPCS matrix.
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    Characterization of an antibacterial wound dressing from basil seed (Ocimum basilicum L.) mucilage-ZnO nanocomposite
    (2019-08-15)
    Tantiwatcharothai, Siriporn
    ;
    The large water holding capacity of Basil Seed (Ocimum basilicum L.) Mucilage (BSM) gives it potential to produce a valuable polymer for water holding applications such as wound dressing. The objective of this research was to prepare a natural-based antibacterial wound dressing from BSM by freeze-drying. Various contents of zinc oxide nanoparticles (ZnO-NP) were incorporated as an antibacterial agent. BSM hydrogel sponge showed considerable porosity and degree of swelling. From FTIR analysis, hydrogen bond and electrostatic interaction between BSM molecules and ZnO-NP were confirmed. SEM images revealed an interconnecting open-cell structure of pores in the BSM hydrogel sponge with a good distribution of ZnO-NP. Moreover, increase in ZnO-NP content improved the mechanical properties (stress at maximum load 8.9 MPa, Young's modulus 151 MPa and strain at maximum load 51%), thermal properties, water retention capacity and antibacterial activity. Cytotoxicity and cell adhesion studies of BSM hydrogel sponge indicated non-cytotoxicity and non-adherent nature of the sponge.
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    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
    ;
    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.
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    Effect of pectin particles and cotton fibers on properties of thermoplastic cassava starch composites
    (2016-03-01) ;
    Pattanasin, Worawan
    Due to poor mechanical properties and high water uptake of thermoplastic starch (TPS), this research focused on property improvement of thermoplastic cassava starch (TPCS) using natural compatible polymers, i.e. pectin particles and cotton fibers. Different TPCS composites, reinforced by the pectin particles and/or the cotton fibers, were compounded and shaped using an internal mixer and a compression molding machine, respectively. It was found from infrared (IR) spectra that the peak position of O-H stretching of the TPCS polymer clearly shifted to lower wavenumber by the addition of the pectin particles and/or the cotton fibers. Moreover, the significant increase of stress at maximum load and Young’s modulus of the TPCS/pectin particle and the TPCS/cotton fiber composites was observed. The drop of water uptake was also found when the cotton fibers were incorporated into the TPCS matrix with/without pectin particles. In addition, X-Ray Diffraction, Scanning Electron Microscopy and Thermogravimetric Analysis were used to characterize different TPCS composites.
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    Properties of thermoplastic rice starch composites reinforced by cotton fiber or low-density polyethylene
    (2010-06-11) ;
    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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    Property improvement of thermoplastic mung bean starch using cotton fiber and low-density polyethylene
    (2010-08-01) ;
    Hommanee, Luxsana
    ;
    Phosee, Darin
    ;
    Chairapaksatien, Parichat
    Due to high water uptake and low mechanical properties of biodegradable thermoplastic starch, thermoplastic starch prepared from mung bean starch (TPMBS) was modified by the incorporation of cotton fiber and low-density polyethylene (LDPE). The effect of different ratios of cotton fiber/LDPE, i.e., 10:0, 7:3, 5:5, 3:7, and 0:10, on water uptake, mechanical, thermal, and biodegradable properties of TPMBS was examined. Different TPMBS samples were prepared using internal mixer for compounding and compression molding machine for shaping samples. It was found that the TPMBS incorporated with 10:0, 7:3, and 3:7 cotton fiber/LDPE showed an increase in the stress at maximum load and Young's modulus. Moreover, the water absorption of all of the modified TPMBS samples tended to decrease as compared to the pure TPMBS. Morphological, thermal, and biodegradable properties of different TPMBS samples were also investigated. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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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) ;
    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.