Papers by Author: Mei Fang Zhu

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Authors: Jing Jing Zhang, Jun Liu, Hao Yu, Yu Zhang, Mei Fang Zhu, Yan Mo Chen
Abstract: Crosslinked UPM/PHBV/PVP fibers were successfully prepared using electrospinning process. The active pharmaceutical ingredient tetracycline hydrochloride (TH) was loaded onto the electrospun fibers through after-treatment method. Scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) and in vitro dissolution tests were carried out to characterize the medicated electrospun fibers. The SEM and FTIR results clearly showed the difference between the UPM / PHBV and UPM/ PHBV/ PVPelectrospun fibers. The pharmaceutical tests results indicated that the fibers had good drug-loaded capability and sustained-release properties. The as-prepared fibers might find possible applications as wound dressings or transdermal drug delivery systems.
Authors: Feng Wei Liu, Jing Hang Hu, Rui Li Wang, Ying Ying Pan, Xiao Ze Jiang, Mei Fang Zhu
Abstract: Hydroxyapatite (HAP), as an essential component of bone and tooth, is one of the promising bioactive materials. The purpose of this study was to investigate the effects of incorporation of nanoHAP and SiO2 particles on the properties of bioactive dental composite. Silanized HAP and SiO2 were mixed with BisGMA/TEGDMA (1/1 wt/wt) monomers at various HAP/SiO2 mass ratios of 0:7 (no HAP), 5.25/1.75, 3.5/3.5, 1.75/5.25, 7:0 (no SiO2) to yield a series of pastes all containing 70 wt% filler loading. The results showed that flexural strength, elastic modulus and compressive strength gradually decreased with increasing amount of HAP particles, as well as curing depth and polymerization shrinkage, which resulted from the nature of HAP particle material. Water sorption and solubility in water increased slightly with addition of HAP particles. Degree of conversion test could support results above well. Remineralization test in SBF demonstrated dental composite with HAP particles had a good apatite-forming ability. Consequently, dental composite filled with lower amount of nanoHAP (HAP/SiO2 around 0.25) particles would possess better comprehensive performances.
Authors: Feng Su, Hao Yu, Shu Qi Zhu, Wen Juan Chen, Fang Huang, Mei Fang Zhu
Abstract: Biodegradable polymeric nanofibers produced by electrospinning have been used as scaffolds for tissue engineering. As one kind of biodegradable material, electrospun polylatic acid fibers have an important application on biomedical materials. For better application of this kind of material, the properties of annealed electrspun poly (L-lactic acid) (PLLA) was studied in this investigation. The material properties of as-spun and annealed nanofibers were studied using differential scanning calorimeter (DSC), X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). Thermal and XRD analysis revealed that PLLA as-spun fiber exhibited amorphous phase and began to crystalline when annealing temperature was above its glass transition temperature. SEM measurements of annealed fibers showed that fusion among fibers occurred when annealing temperature was too high.
Authors: Zhe Zhou, Hou Yong Yu, Mei Fang Zhu, Zong Yi Qin
Abstract: The composites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with different microcrystalline cellulose (MCC) contents were prepared by a solvent casting method. The effects of MCC on the thermal properties of PHBV were studied by TGA and DSC. The DSC results showed that the melt crystallization temperature of the PHBV/MCC increased from 41.9 °C for PHBV to 59.8 °C for the composites containing 20 wt. % MCC, which indicated that the crystallization of PHBV became easier with the addition of MCC. It also illustrated that the MCC could be used as an effective nucleation agent for the crystallization of PHBV. Moreover, it was found that the thermal stability of the PHBV/MCC composites increased compared with the neat PHBV.
Authors: Wen Jiao Li, Wu Jun Ma, Zhou Qi Meng, Meng Ge Xia, Xue Fen Wang, Mei Fang Zhu
Abstract: Zirconium oxide (ZrO2) nanoparticles with the sizes of 50 nm were prepared via hydrothermal method and utilized to prepare zirconia/polyacrylamide (ZrO2/PAAm) nanocomposite hydrogels through conventional radical polymerization at mild condition. The morphology and crystalline structure of prepared ZrO2 were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), and the resultant ZrO2/PAAm nanocomposite hydrogels were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and dental ray machines. The results show that the ZrO2/PAAm nanocomposite hydrogels have a certain X-ray radiopacity and stability under simulated human oral conditions, which have the great potential to be used as root canal filling materials.
Authors: Pei Liu, Long Chen, Jun Xu, Mei Fang Zhu, Zong Yi Qin
Abstract: Biodegradable composites were prepared by adding hyperbranched poly (ester amide) (HBPs) into poly (3-hydroxybutyrate-co-3-hydrovalerate) (PHBV) through melt blending method. It was found that the tensile strength and toughness of PHBV were simultaneously enhanced by the addition of HBPs. Compared with neat PHBV, the tensile strength of the composite increased about 23% from 20.96 to 25.87 MPa for the content of 2.5 wt.% HBPs, and more remarkable enhancement in tensile elongation at break can be achieved by about 88% for 5 wt.% HBPs. The influences of HBPs on crystallization, thermal and fracture morphologies of PHBV were further evaluated by using differential scanning calorimeter and scanning electron microscope, respectively. The decrease in the crystallinity of PHBV and high dispersion of the HBPs in PHBV matrix were observed, which should contribute to the improvement on the mechanical properties of PHBV.
Authors: Si Deng Zhang, Ren Lin Wang, Shi Chao Wang, Zhe Zhou, Bin Sun, Mei Fang Zhu
Abstract: Modified nanosilica (M-SiO2) by coupling agent (KH570, γ-MPS) with C=C bond reinforced ethylene-octene copolymer (POE) nanocomposites were prepared by melt blend, and then irradiated by γ-rays under nitrogen. The results of the crosslinking degree measurement revealed that the crosslinking degree of POE/modified nanosilica composites depended on the modified nanosilica particle size, content and the absorbed dose. Compared with the gel fraction of neat POE which is about 1.8%, the gel fraction of POE/15-M-SiO2-20 improves significantly to 34.2% at very low dose of 40kGy. Moreover, when nanosilica particle size become smaller, the sensitization effect is more obvious at a constant loading level. In comparison to the neat POE with a tensile strength of 22.6MPa, the tensile strength of POE/15-M-SiO2-10 nanocomposites increased to 29.1MPa with an absorbed dose of 100kGy, whereas their elongation at break were gradually reduced with an increasing absorbed dose. The improvement of gel content led to the enhancement of thermal deformation performance of POE/M-SiO2 nanocomposites attributed to the formation of crosslinked network between POE and modified nanosilica by radiation.
Authors: Hong Zhi Wang, Qi Zhang, Yun Xin Gu, Yao Gang Li, Mei Fang Zhu
Abstract: Ti0.6Cr0.4OxNy bimetallic metal oxynitride nano powder was synthesized by ammonolysis of the nanosized Cr2O3/TiO2 composite powder with n(Ti):n(Cr)=6:4 at 800oC for 8 h. The precursor and the resulting oxynitride were characterized by Auger electron spectroscope (AES), X-ray diffraction analysis (XRD), electron probe microanalysis (EPMA), transmission electron microscopy (TEM), and BET surface area techniques. The result indicated that the precursor was homogenous mixture of Cr2O3 and TiO2 with high BET surface area. The as-synthesized oxynitride powder contains only Ti0.6Cr0.4OxNy with cubic structure. The BET surface area of the oxynitride powder is 37.42 m2/g and the particle size is in the range of 20~30 nm.
Authors: Meng Ge Xia, Sheng Liu, Yi Heng Wang, Yan Zhang, Yong Tao Wu, Mei Fang Zhu
Abstract: A novel hybrid hydrogel (SAT gel) based on covalent crosslinking was prepared by photoinitiated polymerization. Photoactive polystyrene (PS) nanoparticles were successfully synthesized by grafting photoinitiator 2-[p-(2-hydroxy-2-methylpropiophenone)] ethylene glycol methacrylate (HMEM) onto the surface of PS nanoparticles, and characterized by nuclear magnetic resonance (NMR), fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscope (HRTEM) and dynamic light scattering (DLS). In the presence of monomer (AAm), PS nanoparticles acting as multifunctional cross-linking agents, and in-situ polymerization was carried out on the surface of photoactive particles. This study focused on the effect of photoactive PS nanoparticles concentration and illumination time on the morphology and swelling behavior of SAT hydrogels. It revealed that the three-dimensional structure and swelling ratio decreased with the increasing concentration of PS nanoparticles. Moreover, the pore size compressed with extending the illumination time. Embedding photoactive nanoparticles into hydrogels network to prepare novel hydrogels had advantages of controllable polymerization process and short forming time. This method provided a new way to prepare soft materials and to design the intelligent hydrogels.
Authors: Zhi Hao Wu, Li Li Li, Shuai Shuai Jiang, Ze Xu Hu, Yu Chen Mao, Mei Fang Zhu
Abstract: Recycled-polyester (RPET) was melt blended with the phosphorus-containing flame retardant (FRP) and α-zirconium phosphate (α-ZrP). The thermal properties of RPET/FRP/α-ZrP composites were analyzed. Modified RPET fibers were prepared through melt spinning of dried RPET nanocomposite chips. The mechanical properties and fire-retardant properties of RPET/FRP/α-ZrP fibers containing different α-ZrP contents were tested. The results show that the synergism of α-ZrP and FRP exerts a positive effect on the mechanical and the flame-retardant property of RPET, leading to nanocomposite fibers of 1.9cN/dtex and 31.6% limiting oxygen index (LOI) value.
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