This work aimed to develop a novel epoxy-modified tung oil waterborne insulation varnish with blocked hexamethylene diisocyanate as a curing agent. The Diels–Alder reaction between tung oil and maleic anhydride, and the ring-opening esterification reaction of epoxy resin were confirmed. The conversion rate of epoxy was explored as a function of reaction time and temperature. The effects of epoxy resin content on the thermal stability, water absorption and insulation properties (insulation strength, volume resistivity, and surface resistivity) of films were investigated, and the resistances of films to salted water were evaluated. The increase in epoxy resin contents could improve the thermal stability and insulation properties of films, and decreased the water adsorption of films, but when the epoxy resin content reached 30% and above, the water solubility of resin became poor. After being immersed in 3.5 wt % NaCl solution, the electrical insulation strength of films were lower than that in dry state, and decreased as the immersed time prolonged. In particular, the electrical insulation strength loss of films increased significantly for epoxy resin content at 15% and below. Furthermore, the increase of epoxy resin content could improve the hardness and adhesion of films, but the flexibility of films became worse. On the basis of experimental, the epoxy resin content at 25% was appropriate to prepare waterborne epoxy-modified tung oil resin. The resulting varnish may have potential as an immersing insulation varnish for the spindle of electric motor. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42755.

Tetracycline hydrochloride loaded poly (vinyl alcohol)/chitosan/ZrO₂ (Tet-PVA/CS/ZrO₂) hybrid nanofibers were fabricated via electrospinning technique. The representative weight ratio of PVA/CS at 3 : 1 was chosen to fabricate drug carrier PVA/CS/ZrO₂ nanofibers. The drug carrier showed a decrease in average diameter with the increase of ZrO₂ content at given conditions, and the nanofibers were uneven and interspersed with spindle-shape beads with ZrO₂ content at 60 wt % and above. The networks linked by hydrogen and Zr–O–C bonds among PVA, CS, and ZrO₂ units resulted in the improving of thermal stability and decreasing of crystallinity of the polymeric matrix. Moreover, the incorporation of ZrO₂ endowed the fibers with ultraviolet shielding effect ranged from 200 to 400 nm. The Tet loading dosage had no obvious effect on the morphology and size of the medicated nanofibers at Tet content below 8 wt %, but interspersed with spindle-shaped beads when Tet content increased to 10 wt %. The Tet-PVA/CS/ZrO₂) nanofibers showed well controlled release and better antimicrobial activity against Staphylococcus aureus, and the Tet release from the medicated nanofibers could be described by Fickian diffusion model for M_t /M_∞< 0.6. These medicated nanofibers may have potential as a suitable material in drug delivery and wound dressing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42506.

An acrylate-modified tung-oil waterborne insulation varnish was synthesized from tung oil, maleic anhydride, and acrylates via a Diels–Alder reaction and free-radical polymerization, and the varnish could be solidified at a relatively low temperature with blocked hexamethylene diisocyanate as a curing agent. The resulting films were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The insulation properties (electrical insulation strength, volume resistivity, and surface resistivity) of the varnish films were tested, and the resistances of films to salted water were evaluated. With an increase in the maleic anhydride content, the thermal stability of the film was improved, whereas the electrical insulation strength, volume resistivity, and surface resistivity decreased. The electrical insulation strength of the film after it was immersed in the NaCl solution was lower than that in dry state, and it decreased as the immersed time was prolonged. In particular, the electrical insulation strength loss of the film increased significantly at maleic anhydride contents beyond 25 wt %. Furthermore, the hardness of the film increased with increasing methyl methacrylate/N-butyl acrylate ratio, whereas the flexibility and adhesion of film decreased to a certain degree at the same time. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41608.

Tetracycline hydrochloride loaded poly(vinyl alcohol)/soybean protein isolate/zirconium (Tet–PVA/SPI/ZrO₂) nanofibrous membranes were fabricated via an electrospinning technique. The average diameter of the PVA/soybean protein isolate (SPI)/ZrO₂ nanofibers used as drug carriers increased with increasing ZrO₂ content, and the nanofibers were uneven and tended to stick together when the ZrO₂ content was above 15 wt %. The Tet–PVA/SPI/ZrO₂ nanofibers were similar in morphology when the loading dosage of the model drug tetracycline hydrochloride was below 6 wt %. The PVA, SPI, and ZrO₂ units were linked by hydrogen bonds in the hybrid networks, and the addition of ZrO₂ improved the thermostability of the polymer matrix. The Tet–PVA/SPI/ZrO₂ nanofibrous membranes exhibited good controlled drug-release properties and antimicrobial activity against Staphylococcus aureus. The results of this study suggest that those nanofibrous membranes were suitable for drug delivery and wound dressing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40903.

On the basis of sol–gel methodology, a novel degradable hybrid electrolyte, poly(lactic acid) (PLA)/poly(methyl methacrylate) (PMMA)/silicon dioxide (SiO₂) hybrid electrolyte, was prepared from PLA, methyl methacrylate, and tetraethoxylsilicon with 3-methacryloxypropyl trimethoxysilane as a coupling agent. As observed from Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy spectra, the PLA, PMMA, and silica units were linked by covalent bonds through the coupling agent in a hybrid network. Differential scanning calorimetry results show that the heat-resistance properties of the hybrid electrolyte improved with increasing SiO₂ content. The hybrid electrolyte was shown to be amorphous by the X-ray diffraction results. From study of ionic conductivity by alternating-current impedance, the ionic conductivity of the PLA/PMMA/SiO₂ hybrid electrolyte increased with increasing silica content, reached a maximum value of 2.42 × 10⁻⁴ S/cm at 2 wt % SiO₂, and then decreased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Based on sol–gel methodology, poly(acrylonitrile-methyl methacrylate) [P(AN-MMA)[/SiO₂ hybrid solid electrolytes were prepared from AN, MMA, and tetraethyl orthosilicate with 3-methacryloxypropyl-trimethoxysilane (KH570) as silane coupling agent. From Fourier transformed infrared spectroscopy and x-ray photoelectron spectroscopy spectra, P(AN-MMA) and silica units are linked by covalent bonds in P(AN-MMA)/SiO₂ hybrid network. Differential scanning calorimetry result shows the glass transition temperature (T_g) of P(AN-MMA)/SiO₂ hybrid material is higher than that of P(AN-MMA) and increases with the increase of silica content. From X-ray diffraction analysis, this hybrid solid electrolyte is amorphous. A study of ionic conductivity by AC impedance suggests that the ionic conductivity of P(AN-MMA)/SiO₂ hybrid solid electrolyte increases with the increase of the silica content and reaches a maximum value of 1.42 × 10⁻³ S cm⁻¹ for 7 wt % SiO₂, and then decreases for SiO₂ > 7 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Poly(lactic acid)–poly(ethylene glycol)–poly(lactic acid) (PLA-PEG-PLA)/SiO₂ hybrid material is prepared by sol–gel method using tetraethoxysilane (TEOS) and PLA-PEG-PLA as raw material. From Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra, the hydroxyl groups of the silica sol derived from partially hydrolysis of TEOS and the unhydrolyzed ethoxy groups of TEOS can react with PLA-PEG-PLA. Differential scanning calorimetry (DSC) curves imply that the glass transition temperature (T_g) of PLA-PEG-PLA/SiO₂ hybrid material is higher than that of PLA-PEG-PLA and increases with the increase of silica content. X-ray diffraction (XRD) analysis results show that PLA-PEG-PLA and PLA-PEG-PLA/SiO₂ hybrid material are both amorphous. Field scanning electron microscope (FSEM) photographs show that when PLA-PEG-PLA/SiO₂ hybrid material has been degraded for 12 weeks in normal saline at 37°C, a three-dimensional porous scaffold is obtained, which is available for cell growth and metabolism. Moreover, the hydroxyl (OH) groups on SiO₂ of PLA-PEG-PLA/SiO₂ hybrid material could buffer the acidity resulted from the degradation of PLA, which is beneficial to proliferation of cell in tissue repairing. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

On the basis of the water solubility of poly(N-vinyl-2-pyrrolidinone), hollow porous poly(lactic acid) microspheres (HPPLAs) were prepared by a water-in-oil-in-water multiple-emulsion solvent evaporation method. The influence of the concentration of the stabilizer Span80 in the oil phase on the morphology was investigated. It was found that when the content of Span80 solutions was 3.5 wt %, most HPPLAs were about 2 μm in diameter. Field scanning electron microscopy results show that the HPPLAs were porous and hollow. The structure and crystal form of the HPPLAs were characterized by Fourier transform infrared spectroscopy and X-ray diffraction analysis. Using these HPPLAs as degradable templates, we successfully synthesized Litchi-like polystyrene (PS) microspheres about 2 μm in diameter by the emulsion method. When used as drug carriers, these HPPLAs would be convenient in which to embed drugs, whereas the Litchi-like PS microspheres may have potential as new materials for polymer modification. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008