Isothermal crystallization behavior of PAR/PBT composite prepared by island-in-a-sea fiber method

The PAR fiber reinforced PBT composite was manufactured using the PAR/PBT island-in-a-sea fiber. The isothermal crystallization kinetics of the PAR/PBT composite and the neat PBT resin were investigated in the temperature range of 187–199 °C. To calculate the Avrami parameters for analyzing the crystallization behavior, crystallization peaks were measured and analyzed in terms of the crystallization temperature and the inclusion of the PAR fiber. The crystallization rate of the PBT is faster than that of the PAR/PBT composite from the analysis of their relative crystallinity. Consequently, it is considered that the PAR fiber interrupted the crystal nucleation and growth of the PBT matrix. It can be confirmed with the crystallization half time and the crystalline morphologies at the chosen isothermal temperatures.     

Titanium dioxide nanofibers prepared by using electrospinning method

The synthesis of titanium dioxide nanofibers with 200–300 nm diameter was presented. The new inorganic-organic hybrid nanofibers were prepared by sol-gel processing and electrospinning technique using a viscous solution of titanium isopropoxide (TiP)/poly(vinyl acetate) (PVAc). Pure titanium dioxide nanofibers were obtained by high temperature calcination of the inorganic-organic composite fibers. SEM, FT-IR, and WAXD techniques were employed to characterize these nanofibers. The titanium dioxide nanostructured fibers have rougher surface and smaller diameter compare with PVAc/TiP composite nanofibers. The anatase to rutile phase transformation occurred when the calcination temperature was increased from 600 °C to 1000 °C.     

Degradation and rheological properties of biodegradable nanocomposites prepared by melt intercalation method

Biodegradable nanocomposites were prepared by mixing a polymer resin and layered silicates by the melt intercalation method. Internal structure of the nanocomposite was characterized by using the small angle X-ray scattering (SAXS) and transmission electron microscope (TEM). Nanocomposites having exfoliated and intercalated structures were obtained by employing two different organically modified nanoclays. Rheological properties in shear and extensional flows and biodegradability of nanocomposites were measured. In shear flow, shear thinning behavior and increased storage modulus were observed as the clay loading increased. In extensional flow, strain hardening behavior was observed in well dispersed system. Nanocomposites with the exfoliated structure had better biodegradability than nanocomposites with the intercalated structure or pure polymer.     

Selective separation of bifenthrin by pH-sensitive/magnetic molecularly imprinted polymers prepared by pickering emulsion polymerization

Via Pickering emulsion polymerization, pH-sensitive magnetic molecularly imprinted polymers (HM-MIPs) were synthesized using bifenthrin (BF) as the template molecule, and pH-sensitive monomer methacrylic acid as the functional monomer. Characterizations of HM-MIPs were achieved by FTIR, TGA, TEM, SEM, and VSM, and the results indicated that HM-MIPs exhibited magnetic property (Ms=1.06 emu/g). HM-MIPs were acted as the adsorbent for a series of adsorption performance testing of BF. Equilibrium data were described by the Langmuir and Freundlich isotherm models. Kinetic properties were successfully investigated by pseudo-first-order model, pseudo-second-order model. The selective recognition experiments exhibited outstanding selectively adsorption effect of the HM-MIPs for target BF over diethyl phthalate and fenvalerate. In water, the HM-MIPs could achieve the adsorption and release of BF by controlling the pH value of the aqueous solution. The results indicated that the molecularly imprinted polymers exhibited good adsorption, selectivity and pH-sensitive performance for BF.     

Fine structure and physical properties of poly(buthylene terephthalate) sheets prepared by roller drawing method

Poly(butylene terephthalate) sheets were prepared by roller-drawing method with various draw ratio. The drawing temperature is 100 °C and draw ratios were varied 2, 2.5, 3, 3.5 and 4. The effect of draw ratio on the crystal structure, the molecular orientation, dynamic viscoelastic properties, sonic modulus and tensile properties of the roller-drawn PBT sheets were investigated. In WAXD results, with increasing of the draw ratio, (010) and (100) planes of preferred orientation have the strongest intensity on the equator. In the meridional scans, it was confirmed that α and β crystal co-existed in the roller drawn PBT sheets with various draw ratio. Uniaxially roller-drawn PBT sheets clearly increased orientation along the stretched direction at high draw ratio. And the four-methylene groups of PBT orient along the surface of the sheet. The mechanical properties of PBT sheets were improved by orientation-induced crystallization during roller drawing process at 100 °C.     

Structures and physical properties of graphene/PVDF nanocomposite films prepared by solution-mixing and melt-compression

We have manufactured poly(vinylidene fluoride) (PVDF)-based nanocomposite films with different graphene contents of 0.1～10.0 wt% by ultrasonicated solution-mixing and melt-compression. As a reinforcing nanofiller, graphene sheets are prepared by rapid thermal expansion of graphite oxide, which are from the oxidation of natural graphite flakes. Graphene sheets are characterized to be well exfoliated and dispersed in the nanocomposite films. X-ray diffraction data confirm that the α-phase crystals of PVDF are dominantly developed in the nanocomposite films during the meltcrystallization. DSC cooling thermograms show that the graphene sheets serve as nucleating agents for the PVDF α-form crystals. Thermal stability of the nanocomposite films under oxygen gas atmosphere is noticeably improved, specifically for the nanocomposite with 1.0 wt% graphene. Electrical volume resistivity of the nanocomposite films is substantially decreased from ～10¹⁴ to ～10⁶ W cm, especially at a critical graphene content between 1.0 and 3.0 wt%. In addition, mechanical storage modulus is highly improved with increasing the graphene content in the nanocomposite films. The increment of the storage modulus for the nanocomposite film at 30 °C with increasing the graphene content is analyzed by adopting the theoretical model proposed by Halpin and Tsai.     

Halochromic chemosensor prepared by pyran-based nanofibers

Colorimetric chemosensors can easily detect and prevent the primary danger or change of the surrounding environmental pollutions and sources of infection in the various fields. Pyran based colorant having the function of colorimetric chemosensor was synthesized. Synthesized colorant was characterized by ¹H NMR, GC-Mass, EA and UV-vis spectroscopy and then mixed with polyacrylonitrile for electrospinning. Electrospun fibers containing pyran based colorant were used as pH detecting chemosensor and were analyzed by SEM, XPS, and spectrophotometer.     

大豆组织蛋白成丝方法探讨

丝状大豆组织蛋白是以大豆分离蛋白和大豆粉为主料制得产品,蛋白质含量在65%以上,广泛地用在食品加工中.利用它作为主要原料,经特殊的工艺加工成肉的替代物(如香肠、丸子、肉松等).由于它可以提高产品的营养价值,改善肉制品的组织结构,提高产品出品率 ,降低成本,增加经济效益,所以市场前景十分广阔. 实验重点探讨几种机械加工方法和加工设备对丝状组织蛋白成丝的影响,分析了四种机械成丝的方法对产品成丝的影响,根据试验总结出合理的机械加工工艺,为机械化的大规模工业生产提供了参考.     

Preparation of poly(vinyl alcohol)/silver-zeolite composite hydrogels by UV-irradiation

Poly(vinyl alcohol) (PVA)/Ag-zeolite nanocomposite hydrogels were prepared by UV irradiation using PVA solution mixed with Ag-zeolite nanoparticles. Physical properties and changes in morphology of the PVA/Ag-zeolite hydrogels were investigated. The PVA/Ag-zeolite hydrogels were prepared at a PVA concentration of 9 wt% with a UV irradiation distance of 15 cm, where gel fraction and swelling ratio were optimized. Hardness of the PVA/Ag-zeolite hydrogels decreased with increasing amounts of Ag-zeolite, reaching that of soft elastomer when the amount of Ag-zeolite was 5 % by weight. The PVA/Ag-zeolite hydrogels showed strong antimicrobial activities against Staphylococcus aureus and Klebsiella pneumoniae, inducing a reduction of bacteria of over 99.9 % at a Ag-zeolite content of 3 wt%.     

Core-sheath polyurethane-carbon nanotube nanofibers prepared by electrospinning

The core-sheath nanofibers consisting of polyurethane (PU) core and PU composites sheath with multi-walled carbon nanotubes (MWNTs) were prepared by electrospinning. At low MWNT concentration, MWNTs appeared highly aligned along the fiber axis with some curving in nanotubes, whereas in case of high concentration, some aggregation of MWNTs appeared due to difficulty in full dispersion of nanotubes. In comparison of the single component nanofiber webs, the core-sheath nanofiber webs showed much better mechanical properties of modulus and breaking stress, including an exceptional elongation-at-break. It indicates that the CNT-incorporated core-sheath structure is very effective for enhancing the mechanical properties of nanofiber webs. In addition, the core-sheath nanofibers demonstrated the fast shape recovery, compared with one component fibers of pure shape memory PU and PU/MWNTs, which provides the possibility of fabricating more sensitive intelligent materials.     

Analysis of fingertip/textile friction-induced vibration by time-frequency method

Tactile textures of textiles depend on the non-linear friction vibrations which are generated by the fingertip sliding across textile surfaces. It is relatively difficult to understand these complex vibrations, since skin and textile are viscoelastic and their vibration spectra are too redundant. Currently, the method of handling such complex vibrations in the field of tactile evaluation and tactile rendering usually adopts Fourier analysis. Unfortunately, only Fourier analysis can neither trace the multi-scales surface textures nor delete the redundant information. This paper proposed a time-frequency analysis, which extends the recorded 1-D vibration signals to 2-D time-frequency spaces to realize the multi-scales decomposition and dimension reduction. By applying this method to four typical kinds of texture surfaces, such as grille and textiles, the results demonstrated that the time-frequency analysis can accurately capture the major textural features from friction-induced vibration signals and decrease the dimensionality of complex signals. Considering the merits of dimension reduction, the time-frequency analysis could use in the texture synthetic of tactile virtual rendering and the tactile design of textile products.     

Novel fibers prepared from cellulose in NaOH/thiourea/urea aqueous solution

The regenerated cellulose fibers were prepared by wet-spinning from NaOH/thiourea/urea aqueous solvent system for the first time. The effects of coagulation and stretch conditions on the structure, morphology, and mechanical properties of the prepared fibers were investigated by wide-angle X-ray diffraction (WAXD), scanning electron microscope (SEM), and tensile tester, respectively. When the cellulose spinning dope was coagulated in 10% H₂SO₄/12.5% Na₂SO₄ aqueous solution at 15 °C, the prepared fibers had a typical crystalline structure of cellulose II and circular cross-sectional shapes with smooth surface and slightly high tensile properties to viscose fibers.     

Carbon nanotube/poly(vinyl alcohol) fibers with a sheath-core structure prepared by wet spinning

A method for manufacturing sheath-core structured fibers was developed using wet spinning techniques. The core portion of a fiber was prepared using a carbon nanotube (CNT) solution while the sheath used a fiber-forming polymer such as polyvinyl alcohol (PVA). Preparation methods of CNT solutions were investigated and it was found that dispersivity and concentration played an important role in the formation and spinning of fiber??s core. CNT solution prepared using a surfactant with high molecular weight such as sodium lignosulfonate (SLS) was most effective and the CNT concentration was as high as 30 g/l. Fiber processing conditions were optimized and it was determined that stretching fibers in the coagulation bath was a significant step in the formation of a solid and well structured core. Drawn fibers were so strong and flexible that they could be woven into a fabric for potential use as a pressure sensor. These results are relevant for practical applications, such as the development of large-area fabric sensors. Furthermore, the described procedure to produce sheath-core CNT fibers is scalable as wet spinning methods have been widely used in the fiber industry.     

Conductive aramid fiber with Ni-Cu composite coating prepared using the metalation swelling method

Conductive aramid fiber with nickel-copper composite coating is prepared by consecutive steps of metalation swelling, sensitization, activation, nickel electroless deposition, and copper electroless deposition, respectively. The metalation swelling of aramid fiber makes the follow-up sensitization and activation feasible. The as-prepared samples are characterized by SEM, TEM, XRD and XPS. After metalation swelling, the aramid fibers look like cotton fibers with numerous nano-scale pits of 50–300 nm in diameter. Pd metal as nuclei for Ni crystal growth with the size of 10±5 nm is originated from Pd²⁺, which can be reduced to Pd⁰ by Sn²⁺. The Ni-Cu composite coating of 1-µm thickness has polycrystalline structure. And the electrical resistance of conductive Ni-Cu aramid fiber is 0.035 Ω/cm. The synthesis mechanism of the conductive aramid fiber with Ni-Cu composite coating is given.     

Properties of starch-palmitic acid complexes prepared by high pressure homogenization

Aqueous mixtures of defatted corn starch and palmitic acid were heated and high pressure homogenized in order to form amylose inclusion complexes. The effects of homogenization pressure (0–120 MPa) and palmitic acid concentration (0.5–8% based on starch content) on starch-palmitic acid complex formation as well as on complex index, X-ray diffraction, thermal properties, viscosity and particle size were investigated. Complex index increased with an increase in the amount of palmitic acid and homogenization pressure, and reached a maximum value (about 60%) when the fatty acid content was 4% and the homogenization pressure was 100 MPa. X-ray diffraction patterns indicated the formation of V-helical complexes between starch and palmitic acid. This technology could prospectively be used in prepared starch-lipid complexes.     

用物性测定仪测定大豆分离蛋白的凝胶性

本文叙述了物性测定仪在大豆分离蛋白凝胶性测定的意义和使用方法。     

Water repellent cotton fabrics prepared by PTFE RF sputtering

A poly(tetrafluoroethylene) (PTFE) sputtering technique was employed to introduce water repellency onto the surfaces of commercial cotton fabrics. Sputtering power, time, and argon pressure were varied as processing parameters, when PTFE coatings were applied on the fabrics. Total 27 different samples were prepared to compare their water repellent properties, which were investigated by contact angle measurements. Morphology of the PTFE coatings were probed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also, the extent of the coating was examined by X-ray photoelectron spectroscopy (XPS). Maximum hydrophobicity was obtained when PTFE coating was extensive enough to cover cotton fabrics almost completely, and the extensive coating was the roughest among the samples prepared in this study.     

Characterization and In Vitro digestibility of rice protein prepared by enzyme-assisted microfluidization: Comparison to alkaline extraction

Microfluidization followed by density-based separation was employed to extract protein from broken rice by disrupting protein-starch agglomerates. Follow-up enzyme treatments (amylase and glucoamylase) were performed to further improve the purity of the protein-rich fraction. High protein recovery (81.87%) and purity (87.89%) were obtained. The protein composition, solubility, structural properties, and in vitro digestibility of rice proteins prepared by enzyme-assisted microfluidization (EM-RP) and alkaline extraction (AE-RP) were compared. EM-RP was mainly composed of glutelin, which had low solubility and native structure. By contrast, large quantities of prolamin and globulin appeared in the AE-RP except glutelin, leading to the richness of glutamic acid/glutamine, leucine, aromatic and charged amino acids in the AE-RP. Compared to AE-RP, EM-RP showed higher digestibility due to the richness of glutelin (an easy-to-digest protein), as evidenced by higher nitrogen release during pepsin-trypsin digestion. The presence of prolamin (an indigestible protein) in AE-RP decreased protein digestibility although alkaline extraction improved its hydrolysis. These results suggest that enzyme-assisted microfluidization could be an effective technique to non-destructively and selectively extract rice glutelin.     

The effects and roles of PVP on the phase composition, morphology and magnetic properties of cobalt ferrite nanoparticles prepared by thermal treatment method

Cobalt ferrite nanocrystals were prepared from an aqueous solution containing metal nitrates and various of concentrations of poly(vinyl pyrrolidone), followed by calcinations temperature. X-ray diffraction (XRD) analysis was performed to determine the degree of crystallinity of the ferrite nanoparticles. By transmission electron microscopy (TEM), the morphology and average particle size of the cobalt ferrite nanoparticles were evaluated which had good agreement with XRD results. Fourier transform infrared spectroscopy (FT-IR) suggested the presence of metal oxide bands in all samples as well as the effective elimination of organic constituents after calcinations. Vibrating sample magnetometer (VSM), was utilized to evaluate the magnetic properties of the cobalt ferrite nanoparticles.