The current work explores the potential use of commercial Chinese bayberry tannin(BT)to develop antioxidant PVA-based films using solvent casting process for packaging applications.The effect of BT concentration on op...The current work explores the potential use of commercial Chinese bayberry tannin(BT)to develop antioxidant PVA-based films using solvent casting process for packaging applications.The effect of BT concentration on opa-city,water resistance and antioxidant capacity of resulting films was investigated.Properties like tensile strength,thermal behavior,and morphological aspects were also characterized.The experimental results showed that PVA/BT films formed with uniformly brown color and generally good transparency,offering good antioxidant ability.The PVA film containing BT presented slightly higher water resistance according to the results of moisture content and water vapor permeability,especially at low BT content(<10 wt%).The PVA can be compounded with up to 10 wt%BT without any obvious deterioration in the tensile strength.The PVA/BT films exhibited better thermal degradation behavior compared with PVA alone because of the chemical bonds of PVA-BT and the for-mation of char at high temperature.Based on the results,PVA incorporated with Chinese bayberry tannin may provide broader formulation options for packaging materials with antioxidant action.展开更多
Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made ...Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made from Polyvinyl Alcohol (PVA) have received considerable attention in recent years. The investigation of surface resistivities of both such films, to this point, has received far less consideration in comparison to pyroelectric effects. In this research, we report temperature dependent surface resistivity measurements of commercial, and of multiwall carbon nanotubes (MWCNT), or Ag-nanoparticle doped PVA films. Without any variation in the temperature range from 22°C to 40°C with controlled humidity, we found that the surface resistivity decreases initially, reaches a minimum, but rises steadily as the temperature continues to increase. This research was conducted with the combined instrumentation of the Keithley Model 6517 Electrometer and Keithley Model 8009 resistivity test fixture using both commercial and in-house produced organic thin films. With the objective to quantify the suitability of PVDF and PVA films as IR detector materials, when using the surface resistivity phenomenon, instead of or in addition to the pyroelectricity, surface resistivity measurements are reported when considering bolometry. We found that the surface resistivity measurements on PVA films were readily implemented.展开更多
A novel method for preparing metalllzed film has been studied.The reduction process and properties of the poly(vinyl alcohol)(PVA)were probed by several analytic means.According to the etudies,a mechanism for the poly...A novel method for preparing metalllzed film has been studied.The reduction process and properties of the poly(vinyl alcohol)(PVA)were probed by several analytic means.According to the etudies,a mechanism for the polymer surface reduction metallization was proposed and proved.展开更多
Cellulose nanocrystals isolated from water hyacinth fiber(WHF)have been studied as a reinforcement for polyvinyl alcohol(PVA)-gelatin nanocomposite.Central composite design was used to study and optimize effects of th...Cellulose nanocrystals isolated from water hyacinth fiber(WHF)have been studied as a reinforcement for polyvinyl alcohol(PVA)-gelatin nanocomposite.Central composite design was used to study and optimize effects of the PVA,gelatin and cellulose nanocrystal(CNC)concentration on tensile strength and elongation of formed films.The results of this study showed that WHF CNC had a diameter range of 20-50 nm produced films reaching 13.8 MPa tensile strength.Thermal stability of the films was improved from 380℃ to 385℃ in addition of CNCs and maximum storage modulus of 3 GPa were observed when 5 wt%CNC was incorporated.However,water absorption,water vapour permeability(WVP)and moisture uptake of the films decreased in addition of CNC to the PVA-gelatin blends.Moisture uptake decreased from 22.50%to 19.05%while the least WVP when 10 wt%CNC added was 1.64×10^(-6)g/(m·h·Pa).These results show possibility for industrial application of WHF CNC and PVA-gelatin blends in biodegradable films for on-the-go food wrappers.展开更多
基金This work was supported by the National Natural Science Foundation of China(NSFC 31971595,31760187)the Program for Leading Talents of Science and Technology(Grant No.2017HA013)the Yunnan Provincial Reserve Talents for Middle&Young Academic and Technical Leaders(2019HB026),and the 111 Project.
文摘The current work explores the potential use of commercial Chinese bayberry tannin(BT)to develop antioxidant PVA-based films using solvent casting process for packaging applications.The effect of BT concentration on opa-city,water resistance and antioxidant capacity of resulting films was investigated.Properties like tensile strength,thermal behavior,and morphological aspects were also characterized.The experimental results showed that PVA/BT films formed with uniformly brown color and generally good transparency,offering good antioxidant ability.The PVA film containing BT presented slightly higher water resistance according to the results of moisture content and water vapor permeability,especially at low BT content(<10 wt%).The PVA can be compounded with up to 10 wt%BT without any obvious deterioration in the tensile strength.The PVA/BT films exhibited better thermal degradation behavior compared with PVA alone because of the chemical bonds of PVA-BT and the for-mation of char at high temperature.Based on the results,PVA incorporated with Chinese bayberry tannin may provide broader formulation options for packaging materials with antioxidant action.
文摘Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made from Polyvinyl Alcohol (PVA) have received considerable attention in recent years. The investigation of surface resistivities of both such films, to this point, has received far less consideration in comparison to pyroelectric effects. In this research, we report temperature dependent surface resistivity measurements of commercial, and of multiwall carbon nanotubes (MWCNT), or Ag-nanoparticle doped PVA films. Without any variation in the temperature range from 22°C to 40°C with controlled humidity, we found that the surface resistivity decreases initially, reaches a minimum, but rises steadily as the temperature continues to increase. This research was conducted with the combined instrumentation of the Keithley Model 6517 Electrometer and Keithley Model 8009 resistivity test fixture using both commercial and in-house produced organic thin films. With the objective to quantify the suitability of PVDF and PVA films as IR detector materials, when using the surface resistivity phenomenon, instead of or in addition to the pyroelectricity, surface resistivity measurements are reported when considering bolometry. We found that the surface resistivity measurements on PVA films were readily implemented.
基金The project surported by State"863"PlanNational Natural science fund.
文摘A novel method for preparing metalllzed film has been studied.The reduction process and properties of the poly(vinyl alcohol)(PVA)were probed by several analytic means.According to the etudies,a mechanism for the polymer surface reduction metallization was proposed and proved.
文摘Cellulose nanocrystals isolated from water hyacinth fiber(WHF)have been studied as a reinforcement for polyvinyl alcohol(PVA)-gelatin nanocomposite.Central composite design was used to study and optimize effects of the PVA,gelatin and cellulose nanocrystal(CNC)concentration on tensile strength and elongation of formed films.The results of this study showed that WHF CNC had a diameter range of 20-50 nm produced films reaching 13.8 MPa tensile strength.Thermal stability of the films was improved from 380℃ to 385℃ in addition of CNCs and maximum storage modulus of 3 GPa were observed when 5 wt%CNC was incorporated.However,water absorption,water vapour permeability(WVP)and moisture uptake of the films decreased in addition of CNC to the PVA-gelatin blends.Moisture uptake decreased from 22.50%to 19.05%while the least WVP when 10 wt%CNC added was 1.64×10^(-6)g/(m·h·Pa).These results show possibility for industrial application of WHF CNC and PVA-gelatin blends in biodegradable films for on-the-go food wrappers.
