Blown films based on low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE) and ... more Blown films based on low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE) and silica aerogel (SA; 0, 0.5, 1, and 1.5 wt.%) were obtained at the pilot scale. Good particle dispersion and distribution were achieved without thermo oxidative degradation. The effects of different SA contents (0.5–1.5 wt.%) were studied to prepare transparent-heat-retention LDPE/LLDPE films with improved material properties, while maintaining the optical performance. The optical characteristics of the composite films were analyzed using methods such as ultraviolet–visible spectroscopy and electron microscopy. Their mechanical characteristics were examined along the machine and transverse directions (MD and TD, respectively). The MD film performance was better, and the 0.5% composition exhibited the highest stress at break. The crystallization kinetics of the LDPE/LLDPE blends and their composites containing different SA loadings were investigated using differential scanning calorimetry,...
Fog is a resource with great potential to capture fresh water from the atmosphere, regardless of ... more Fog is a resource with great potential to capture fresh water from the atmosphere, regardless of the geographical and hydrological conditions. Micro-sized fog collection requires materials with hydrophilic/phobic patterns. In this study, we prepared hydrophilic poly(lactic acid) (PLA)/poly(ethylene glycol)-poly(propyl glycol)-poly(ethylene glycol) (PEG-PPG-PEG) blended nanofiber membranes with various PEG-PPG-PEG concentrations by electrospinning. Changes in the morphological and chemical properties, surface wettability, and thermal stability of the PLA/PEG-PPG-PEG composite nanofiber membranes were confirmed using field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, contact angle testing, and thermogravimetric analysis. As the PEG-PPG-PEG content of the nanofiber membranes increased, their hydrophilicity increased. Water stability, membrane porosity, and water transport rate tests were also conducted to observe the behavior of the...
Novel poly(vinyl alcohol) (PVA)/poly(vinyl butyral–vinyl alcohol) (P(VB-VA)) films with improved ... more Novel poly(vinyl alcohol) (PVA)/poly(vinyl butyral–vinyl alcohol) (P(VB-VA)) films with improved hydrophobicity were prepared from poly(vinyl acetate) (PVAc)/poly(vinyl butyral) (PVB) blend films with various mass ratios by saponification in a heterogeneous medium. The successful conversion of PVAc to PVA and PVAc/PVB to PVA/P(VB-VA) films was confirmed by Fourier transform infrared spectrometry, X-ray diffraction, and proton nuclear magnetic resonance analysis. This study also shows that the degree of saponification (DS) depends on the saponification time. The maximum DS of 99.99% was obtained at 96 h of saponification for all films, and the presence of PVB did not affect the DS at saponification times of 48–96 h. The effects of the PVAc/PVB blend ratio before and after saponification were determined by contact angle measurement, and the hydrophobicity was found to increase in both cases with increasing PVB content. Additionally, all the films exhibited improved mechanical properti...
For the first time, poly(vinyl alcohol) (PVA)/poly(methyl methacrylate–methallyl alcohol) (P(MMA-... more For the first time, poly(vinyl alcohol) (PVA)/poly(methyl methacrylate–methallyl alcohol) (P(MMA-MAA)) (9:1, 7:3, 5:5) blend films were made simultaneously using the saponification method in a heterogeneous medium from poly(vinyl acetate) (PVAc)/poly(methyl methacrylate) (PMMA) (9:1, 7:3, 5:5) blend films, respectively. The surface morphology and characteristics of the films were investigated using optical microscopy (OM), atomic force microscopy (AFM), X-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Moreover, the effect of the PVAc content on the degree of saponification (DS) of the PVAc/PMMA films were evaluated and revealed that the obtained DS value increased with the increase in PVAc content in the PVAc/PMMA blend films. According to the OM results, the saponified films demonstrated increased surface roughness compared with the unsaponified films. The AFM images revealed m...
Hybrid nanobiocomposite films are prepared using a solution casting by incorporating TEMPO cellul... more Hybrid nanobiocomposite films are prepared using a solution casting by incorporating TEMPO cellulose nanofibrils (TOCNs) and carbon nanotubes (CNTs) into an aqueous solution of pullulan (PULL). The presence of CNT is confirmed by XRD characterization, and the prepared film shows an increased degree of crystallinity after the addition of TOCNs and CNT. The maximum degree of crystallinity value is obtained for CNT 0.5 % (59.64%). According to the Fourier-transform infrared spectroscopy, the shifts of the characteristic -OH peak of PULL occurred after the addition of TOCNs and aqueous CNT (3306.39 to 3246.90 cm−1), confirming interaction between the TOCNs, CNTs, and PULL matrix. The prepared films show enhanced material properties including higher tensile strength (65.41 MPa at low CNT content (0.5%)), water barrier properties, and reduced moisture susceptibility (5 wt.% CNT shows the lowest value (11.28%)) compared with the neat PULL film. Additionally, the prepared films are almost b...
Abstract Thermoplastic composites are rapidly emerging as alternative materials for auto parts ow... more Abstract Thermoplastic composites are rapidly emerging as alternative materials for auto parts owing to recyclability as well as excellent stiffness- and strength-to weight ratios. In this study, an optimal stacking sequence using twill-weave carbon fiber-reinforced polypropylene (CF/PP) prepregs and random fiber-reinforced polypropylene (RFP) sheets were investigated for the fabrication of an automobile fender. The lamination consisting of CF/PP only incurred imperfect resin impregnation. RFP insertion between CF/PP layers improved the resin impregnation. The hybrid stacking sequence not only reduced internal void contents but also increased the flexural and impact strength of the composite laminate. Using the optimal stacking sequence, a real-scale composite fender was fabricated and impact tests were performed. The test results were compared with the ones from an existing steel fender. In case of the steel fender, permanent deformation was observed even in one attempt, while no visible damage was found from the composite fender even after five consecutive impact tests.
Poly(vinyl alcohol) (PVA)/pullulan (PULL) blend nanofibres were prepared from their aqueous solut... more Poly(vinyl alcohol) (PVA)/pullulan (PULL) blend nanofibres were prepared from their aqueous solutions by electrospinning method. Polymer solutions with different concentrations and blend ratios were used to investigate the effect of polymer concentrations and blend ratios on the morphologies and properties of PVA/PULL nanofibres. At a fixed blend ratio, the total polymer concentrations were also adjusted to find suitable electrospinning condition for preparing uniform and bead-free nanofibres. The as-prepared nanofibres were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Their mechanical properties were also studied by measuring their tensile strength. The results showed that polymer concentrations and blend ratios have direct influence on the morphologies and properties of PVA/PULL nanofibres. 12 wt.% total polymer concentrati...
Poly(acrylonitrile) (PAN) nanofibres containing variable amounts of titanium dioxide (TiO2) were ... more Poly(acrylonitrile) (PAN) nanofibres containing variable amounts of titanium dioxide (TiO2) were successfully electrospun under different conditions to find optimum electrospinning conditions and to investigate the effects of TiO2 content and electrospinning parameters on the morphologies and thermal properties of PAN/TiO2 nanofibres. Various amounts of TiO2 were dispersed separately into PAN solutions. N, N'-dimethyl formamide (DMF) was used as a solvent. Electrospinning parameters such as applied voltage and tip to collector distance (TCD) were varied at a fixed PAN/TiO2 mixing ratio. The PAN/TiO2 nanofibres containing different amounts of TiO2 were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The results showed TiO2 content and electrospinning parameters have direct influence on the morphologies of PAN/TiO2 nanofibres. Moreover, the addition of TiO2 significantly improved t...
A novel PVA/clay (MMT) film is prepared for the first time based on the saponification of the PVA... more A novel PVA/clay (MMT) film is prepared for the first time based on the saponification of the PVAc/MMT film in the presence of heterogeneous conditions. With the help of optical microscopy, the characteristics and surface morphology of the saponified PVA/MMT film is confirmed. It is found to contain black MMT nanoparticles in PVAc films as the content of MMT increased. According to atomic force microscopy results, PVAc/MMT films shows unexpected surface roughness owing to the slow progress of the saponification reaction in the presence of MMT contents in the PVAc matrix. The thermal stability of the PVA/MMT film is measured using thermal gravimetric analyses. The results indicate that thermal stability increases significantly when the MMT concentration increases. The entire structure of the PVA/MMT nanocomposite has been elucidated using XRD. To prove the differences between the PVAc/MMT and the PVA/MMT films, XRD measurements and Fourier transform Infrared spectroscopy analyses are...
Heating films were prepared by using poly(methyl methacrylate) and polybutadiene composites conta... more Heating films were prepared by using poly(methyl methacrylate) and polybutadiene composites containing graphite. The heating film was prepared by casting the as-made polymer composite on the PET film. Copper electrodes were attached to both ends of the as-prepared film, and the heating characteristics of the film were analyzed while applying the DC voltage. The electrical conductivity and the heating temperature of the heating films depended on the size, the structure, the content, and the dispersion characteristics of the graphite in the composite. The electrical resistance of the heating film was controlled to adjust the heating temperature of the film. The relationship between the physical/chemical structure and the heating characteristics of the composite film was studied by measuring the heating temperature as functions of film thickness and resistance by using an infrared thermal imaging camera. The lower the film resistance, the higher the heating temperature of the film. The...
Blown films based on low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE) and ... more Blown films based on low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE) and silica aerogel (SA; 0, 0.5, 1, and 1.5 wt.%) were obtained at the pilot scale. Good particle dispersion and distribution were achieved without thermo oxidative degradation. The effects of different SA contents (0.5–1.5 wt.%) were studied to prepare transparent-heat-retention LDPE/LLDPE films with improved material properties, while maintaining the optical performance. The optical characteristics of the composite films were analyzed using methods such as ultraviolet–visible spectroscopy and electron microscopy. Their mechanical characteristics were examined along the machine and transverse directions (MD and TD, respectively). The MD film performance was better, and the 0.5% composition exhibited the highest stress at break. The crystallization kinetics of the LDPE/LLDPE blends and their composites containing different SA loadings were investigated using differential scanning calorimetry,...
Fog is a resource with great potential to capture fresh water from the atmosphere, regardless of ... more Fog is a resource with great potential to capture fresh water from the atmosphere, regardless of the geographical and hydrological conditions. Micro-sized fog collection requires materials with hydrophilic/phobic patterns. In this study, we prepared hydrophilic poly(lactic acid) (PLA)/poly(ethylene glycol)-poly(propyl glycol)-poly(ethylene glycol) (PEG-PPG-PEG) blended nanofiber membranes with various PEG-PPG-PEG concentrations by electrospinning. Changes in the morphological and chemical properties, surface wettability, and thermal stability of the PLA/PEG-PPG-PEG composite nanofiber membranes were confirmed using field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, contact angle testing, and thermogravimetric analysis. As the PEG-PPG-PEG content of the nanofiber membranes increased, their hydrophilicity increased. Water stability, membrane porosity, and water transport rate tests were also conducted to observe the behavior of the...
Novel poly(vinyl alcohol) (PVA)/poly(vinyl butyral–vinyl alcohol) (P(VB-VA)) films with improved ... more Novel poly(vinyl alcohol) (PVA)/poly(vinyl butyral–vinyl alcohol) (P(VB-VA)) films with improved hydrophobicity were prepared from poly(vinyl acetate) (PVAc)/poly(vinyl butyral) (PVB) blend films with various mass ratios by saponification in a heterogeneous medium. The successful conversion of PVAc to PVA and PVAc/PVB to PVA/P(VB-VA) films was confirmed by Fourier transform infrared spectrometry, X-ray diffraction, and proton nuclear magnetic resonance analysis. This study also shows that the degree of saponification (DS) depends on the saponification time. The maximum DS of 99.99% was obtained at 96 h of saponification for all films, and the presence of PVB did not affect the DS at saponification times of 48–96 h. The effects of the PVAc/PVB blend ratio before and after saponification were determined by contact angle measurement, and the hydrophobicity was found to increase in both cases with increasing PVB content. Additionally, all the films exhibited improved mechanical properti...
For the first time, poly(vinyl alcohol) (PVA)/poly(methyl methacrylate–methallyl alcohol) (P(MMA-... more For the first time, poly(vinyl alcohol) (PVA)/poly(methyl methacrylate–methallyl alcohol) (P(MMA-MAA)) (9:1, 7:3, 5:5) blend films were made simultaneously using the saponification method in a heterogeneous medium from poly(vinyl acetate) (PVAc)/poly(methyl methacrylate) (PMMA) (9:1, 7:3, 5:5) blend films, respectively. The surface morphology and characteristics of the films were investigated using optical microscopy (OM), atomic force microscopy (AFM), X-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Moreover, the effect of the PVAc content on the degree of saponification (DS) of the PVAc/PMMA films were evaluated and revealed that the obtained DS value increased with the increase in PVAc content in the PVAc/PMMA blend films. According to the OM results, the saponified films demonstrated increased surface roughness compared with the unsaponified films. The AFM images revealed m...
Hybrid nanobiocomposite films are prepared using a solution casting by incorporating TEMPO cellul... more Hybrid nanobiocomposite films are prepared using a solution casting by incorporating TEMPO cellulose nanofibrils (TOCNs) and carbon nanotubes (CNTs) into an aqueous solution of pullulan (PULL). The presence of CNT is confirmed by XRD characterization, and the prepared film shows an increased degree of crystallinity after the addition of TOCNs and CNT. The maximum degree of crystallinity value is obtained for CNT 0.5 % (59.64%). According to the Fourier-transform infrared spectroscopy, the shifts of the characteristic -OH peak of PULL occurred after the addition of TOCNs and aqueous CNT (3306.39 to 3246.90 cm−1), confirming interaction between the TOCNs, CNTs, and PULL matrix. The prepared films show enhanced material properties including higher tensile strength (65.41 MPa at low CNT content (0.5%)), water barrier properties, and reduced moisture susceptibility (5 wt.% CNT shows the lowest value (11.28%)) compared with the neat PULL film. Additionally, the prepared films are almost b...
Abstract Thermoplastic composites are rapidly emerging as alternative materials for auto parts ow... more Abstract Thermoplastic composites are rapidly emerging as alternative materials for auto parts owing to recyclability as well as excellent stiffness- and strength-to weight ratios. In this study, an optimal stacking sequence using twill-weave carbon fiber-reinforced polypropylene (CF/PP) prepregs and random fiber-reinforced polypropylene (RFP) sheets were investigated for the fabrication of an automobile fender. The lamination consisting of CF/PP only incurred imperfect resin impregnation. RFP insertion between CF/PP layers improved the resin impregnation. The hybrid stacking sequence not only reduced internal void contents but also increased the flexural and impact strength of the composite laminate. Using the optimal stacking sequence, a real-scale composite fender was fabricated and impact tests were performed. The test results were compared with the ones from an existing steel fender. In case of the steel fender, permanent deformation was observed even in one attempt, while no visible damage was found from the composite fender even after five consecutive impact tests.
Poly(vinyl alcohol) (PVA)/pullulan (PULL) blend nanofibres were prepared from their aqueous solut... more Poly(vinyl alcohol) (PVA)/pullulan (PULL) blend nanofibres were prepared from their aqueous solutions by electrospinning method. Polymer solutions with different concentrations and blend ratios were used to investigate the effect of polymer concentrations and blend ratios on the morphologies and properties of PVA/PULL nanofibres. At a fixed blend ratio, the total polymer concentrations were also adjusted to find suitable electrospinning condition for preparing uniform and bead-free nanofibres. The as-prepared nanofibres were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Their mechanical properties were also studied by measuring their tensile strength. The results showed that polymer concentrations and blend ratios have direct influence on the morphologies and properties of PVA/PULL nanofibres. 12 wt.% total polymer concentrati...
Poly(acrylonitrile) (PAN) nanofibres containing variable amounts of titanium dioxide (TiO2) were ... more Poly(acrylonitrile) (PAN) nanofibres containing variable amounts of titanium dioxide (TiO2) were successfully electrospun under different conditions to find optimum electrospinning conditions and to investigate the effects of TiO2 content and electrospinning parameters on the morphologies and thermal properties of PAN/TiO2 nanofibres. Various amounts of TiO2 were dispersed separately into PAN solutions. N, N'-dimethyl formamide (DMF) was used as a solvent. Electrospinning parameters such as applied voltage and tip to collector distance (TCD) were varied at a fixed PAN/TiO2 mixing ratio. The PAN/TiO2 nanofibres containing different amounts of TiO2 were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The results showed TiO2 content and electrospinning parameters have direct influence on the morphologies of PAN/TiO2 nanofibres. Moreover, the addition of TiO2 significantly improved t...
A novel PVA/clay (MMT) film is prepared for the first time based on the saponification of the PVA... more A novel PVA/clay (MMT) film is prepared for the first time based on the saponification of the PVAc/MMT film in the presence of heterogeneous conditions. With the help of optical microscopy, the characteristics and surface morphology of the saponified PVA/MMT film is confirmed. It is found to contain black MMT nanoparticles in PVAc films as the content of MMT increased. According to atomic force microscopy results, PVAc/MMT films shows unexpected surface roughness owing to the slow progress of the saponification reaction in the presence of MMT contents in the PVAc matrix. The thermal stability of the PVA/MMT film is measured using thermal gravimetric analyses. The results indicate that thermal stability increases significantly when the MMT concentration increases. The entire structure of the PVA/MMT nanocomposite has been elucidated using XRD. To prove the differences between the PVAc/MMT and the PVA/MMT films, XRD measurements and Fourier transform Infrared spectroscopy analyses are...
Heating films were prepared by using poly(methyl methacrylate) and polybutadiene composites conta... more Heating films were prepared by using poly(methyl methacrylate) and polybutadiene composites containing graphite. The heating film was prepared by casting the as-made polymer composite on the PET film. Copper electrodes were attached to both ends of the as-prepared film, and the heating characteristics of the film were analyzed while applying the DC voltage. The electrical conductivity and the heating temperature of the heating films depended on the size, the structure, the content, and the dispersion characteristics of the graphite in the composite. The electrical resistance of the heating film was controlled to adjust the heating temperature of the film. The relationship between the physical/chemical structure and the heating characteristics of the composite film was studied by measuring the heating temperature as functions of film thickness and resistance by using an infrared thermal imaging camera. The lower the film resistance, the higher the heating temperature of the film. The...
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Papers by Seong Baek Yang