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Author: search.filters.author.Charoonsuk, ThitiratSubject: search.filters.subject.Composite film

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    Item type:Publication,
    Integration of CCTAO/PDMS composite films into proximity capacitive sensor devices
    (2026-12-01)
    Bongkarn, Theerachai
    ;
    Panpho, Phakakorn
    ;
    Charoonsuk, Thitirat
    ;
    Vittayakorn, Naratip
    ;
    Pakawanit, Phakkhananan
    Flexible capacitive proximity sensors are promising for contactless sensing applications, but their performance is strongly influenced by the dielectric properties and microstructure of the sensing layer. In this work, CaCu<inf>3</inf>Ti<inf>4-x</inf>A<inf>x</inf>O<inf>12</inf>/polydimethylsiloxane (CCTAO/PDMS, A = Nd<sup>3+</sup> or Gd<sup>3+</sup>) composite films were developed as flexible dielectric layers for interdigitated capacitive proximity sensors. Nd- and Gd-doped CCTO ceramics were synthesized by a solid-state reaction method and incorporated into a PDMS matrix at different filler loadings. Structural analysis confirmed that the CCTAO ceramics retained the cubic CCTO phase after rare-earth substitution, while the composite films preserved the characteristic amorphous structure of PDMS with embedded ceramic fillers. The FESEM, EDS mapping and X-ray tomographic microscopy analyses showed that the CCTNdO/PDMS composite had a more uniform distribution of ceramic particles than the CCTO/PDMS system. The dielectric measurements demonstrated the improvement in the dielectric constant of the PDMS-based composites upon CCTNdO incorporation and also indicated that the composites did not exhibit any significant changes in their dielectric properties across the range of frequencies examined. The CCTNdO/PDMS films were found to show the negative capacitance response as a function of distance due to the electric-field shunting mechanism when used in an interdigitated capacitor sensor. The sensor with composition 10 wt% CCTNdO/PDMS had excellent performance with a maximum normalized capacitance change equal to −8.70%, which corresponds to a proximity sensitivity of around 0.42%/mm and an effective sensing range of around 20 mm. It is concluded that the optimization of the loading of the rare-earth material in a flexible PDMS matrix is an effective approach to achieve a compromise between the dielectric enhancement of the sensor and the dispersion of the filler and fringing-field interaction in the contactless capacitive proximity sensor.
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    Synthesis and preparation of bacterial cellulose/calcium hydrogen phosphate composite film for mulching film application
    (2021-01-01)
    Pinpru, Nattapong
    ;
    Charoonsuk, Thitirat
    ;
    Khaisaat, Supharada
    ;
    Sawanakarn, Oubonwan
    ;
    Vittayakorn, Naratip
    This research aims to prepare mulching film from starting substrate of Acetobacter xylinum in bacterial cellulose (BC). BC was extracted from rotten coconut fruit. At the same time, CaHPO4 fertilizer was prepared from waste cockle shell. Both BC and CaHPO4 were analyzed by XRD and SEM for investigation of crystal structure and morphology. The results reveal well specific characterization of BC and CaHPO4. The BC and CaHPO4 composite film were further forming by solvent casting method. It was found that the increasing amount of CaHPO4 to 3 and 5%w/w were dramatically increased the percent of water absorption and rate of biodegradation, but it must sacrifice to mechanical properties. The morphology results were also disclosure that the higher amount of CaHPO4 (3 and 5 %w/w) composite film obviously caused phase separation that was correspondent to lower in mechanical properties. Thus, BC/1%CaHPO4 composite film was selected for mulching film because of good mechanical properties and gradually slow degradation.
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