助剂对常温固化FEVE氟碳涂料耐溶剂性能的影响

比较了不同助剂对常温固化型FEVE氟碳涂料涂膜耐溶剂性能的影响,并且分析了其主要原因.     

电纺直写制备聚己内酯支架形貌及精度

作为一种新型的微纳制造技术，熔体直写电纺被广泛用于组织工程支架的可控制备,有序的纤维沉积是该领域应用的前提条件。对于支架成型精度的探究，本文使用生物可降解材料聚己内酯（PCL），采用自行设计的熔体电纺三维可控成型设备进行实验，考察了纤维间距对二维并行纤维沉积形貌及成型精度的影响，以及纺丝电压和网格大小对三维网格结构形貌及精度影响。结果表明，随着并行纤维设定距离的增大，纤维的沉积误差减小，并最终趋于平稳。对于三维网格结构，随电压的增加，最大沉积层数量先增大后减小，当纺丝电压为6kV时达到最大沉积层数15层。成型精度误差先减小后增大，当纺丝电压为7kV时，精度最高误差小于5%。随设定网格边长的增大，沉积层数不断增大。成型精度逐渐提高，当网格边长大于等于1.5mm时，沉积误差趋于稳定，并维持在5%左右。     

常温固化FEVE氟碳涂料耐酸碱性能和耐溶剂性能研究

比较了不同类型FEVE氟碳涂料的耐酸碱性能和耐溶剂性能,并简要分析了原因。     

Preparation and properties of poly(urethane acrylate) films for ultraviolet‐curable coatings

Four different UV‐curable poly(urethane acrylate)s were prepared through the reaction of two diisocyanates [i.e., toluene‐2,4‐diisocyanate (TDI) and isophorone diisocyanate (IPDI)] and two polyols [i.e., polycaprolactone triol (PCLT) and polycaprolactone diol (PCLD)], and they were characterized with Fourier transform infrared spectroscopy. The mechanical properties, thermal properties, and water sorption of the cured poly(urethane acrylate)s were also investigated with respect to the chemical structures of the polyols and diisocyanates. In comparison with linear PCLD–TDI and PCLD–IPDI, crosslinked PCLT–TDI and PCLT–IPDI with trifunctional PCLT showed relatively high thermal decomposition temperatures. The hardness and modulus of the UV‐cured poly(urethane acrylate) films, which were measured by a nanoindentation technique, were in the following increasing order: PCLD–IPDI ～ PCLD–TDI < PCLT–IPDI ～ PCLT–TDI. The pencil hardness was 3H for PCLT–IPDI and PCLT–TDI and HB for PCLD–IPDI and PCLD–TDI. Two urethane acrylates prepared from the trifunctional polyol showed better acid and alkali resistances than those made from the bifunctional polyol. These mechanical properties and chemical resistances may have been strongly dependent on the chain flexibility of the molecules and crosslinking density. Regardless of the functionality in the polyol, the change in the yellowness index showed a lower value in the poly(urethane acrylate) coating containing the aliphatic diisocyanate IPDI in comparison with the corresponding poly(urethane acrylate) with the aromatic diisocyanate TDI. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Precipitation of pharmaceuticals using a supercritical anti‐solvent (SAS) dechnique: A preliminary study

The aims of this research were to investigate the applicability of the supercritical anti‐solvent (SAS) process on the precipitation of pharmaceuticals (andrographolide and acetaminophen). In particular, the goal of this research was to study the influence of pressure at 10 and 24 MPa on particle characteristics (morphology, crystalline structure, polymorphic form, size, size distribution, and precipitation yield), and to compare the precipitation efficiency of SAS process and evaporation process. Scanning electron microscope (SEM), X‐ray diffraction (XRD), and high performance liquid chromatography (HPLC) showed a significant change in particle size, size distribution, morphology, and precipitation yield, respectively. From an analysis of the results it was found that the crystal size of andrographolide and acetaminophen decreased with increasing pressure. The morphology of andrographolide particles changed from slice‐like to column‐like when the pressure was increased. On the other hand, the acetaminophen particles obtained were found to be monoclinic form (I) under both operating pressures. The SAS process produced small uniform shaped crystals, with a narrow size distribution, high precipitation yield and selective precipitation were also observed.     

Mechanical strength and wear resistance of protective coatings applied by fluidized bed (FB)

This study deals with the interrelation between the thermo-rheological behaviour of an epoxy-based powder coating system and its mechanical strength and wear endurance.

Matte-finish protective polymeric films deposited by electrostatic fluidized bed (EFB) and conventional hot dipping fluidized bed (CHDFB) on metal substrates were examined. First, the analysis of thermo-rheological behaviour of the epoxy-based powder coating system was detailed. Secondly, the adhesion strength and wear endurance of polymeric films was related to the thermo-rheological behaviour of the starting material formulation. Finally, based on the experimental data, generalized scratch and wear map, in which the overall mechanical performance of the matte-finish polymeric films at different curing levels is reported, was usefully provided.

The experimental findings lead to further advances in the understanding of the mechanisms involved in the establishment of the overall mechanical performances of fluidized bed (FB) deposited polymeric films. They also provide important indications for the settings of curing parameters or preheating temperatures in FB coating processes as well as for the development of new powder coating formulations.     

Surface structural features and optical analysis of nanostructured Cu-oxide thin film coatings coated via the sol-gel dip coating method

Nanostructured thin film coatings of copper oxide (Cu-oxide) were investigated to determine their physical structure, surface morphology, surface electronic bonding states, and optical properties. The Cu-oxide had been coated onto reflective aluminum substrates via a facile one-step sol–gel dip-coating route using a copper nitrate precursor. Characterizations were conducted using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), and ultra-violet visible (UV–Vis) spectroscopic methods, and representative sol-gel reactions using copper nitrate precursor were proposed. The XPS spectra confirmed the presence of copper oxide elements. Further exploration of the Cu2p3/2 peak in XPS spectra revealed that the electronic structure of the copper component consisted of tetrahedral Cu(I) and octahedral Cu(II) with the presence of octahedral Cu(II) enabling coatings to have high absorption levels across the solar spectrum. The deconvolution of the O1s spectra exhibited three curve-fitting components: the lattice O²⁻, surface oxygen, and subsurface O⁻ species. FESEM results showed that the coating surface was an agglomerated copper oxide nanoparticles structure forming a porous structure. The optical band-gap of Cu-oxide thin film coatings, via the Tauc plot, was 2.7 eV.     

Morphology and biodegradation of microspheres of polyester–polyether block copolymer based on polycaprolactone/polylactide/poly(ethylene oxide)

Porous microspheres of polyester–polyether block copolymer based on polycaprolactone/polylactide/poly(ethylene oxide) (PCEL) were prepared by an emulsification–solvent evaporation technique. The effect of hydrophilicity/hydrophobicity of the polymer on the morphology of the PCEL microspheres was studied and compared with that of polycaprolactone (PCL) and polycaprolactone/poly(ethylene oxide) block copolymer (PCE) microspheres. It was demonstrated by X‐ray photoelectron spectroscopy (XPS) that the enrichment of PEO segments on the surface of the microspheres occurred during solvent evaporation of the microdrops and lead to porous structure of the microspheres. The effects of the content and length of PEO segments of the PCEL polymer on the morphology of the microspheres were studied. The degradation behaviour of film‐like and microsphere‐like PCEL was investigated at pH 7.4 and 37 ± 1 °C. The shape of the PCEL samples had no obvious effect on the degradation rate of the material and homogeneous degradation was a main process. The degradation rate of PCEL microspheres was enhanced in the presence of the enzyme lipase. ¹H NMR measurements revealed that the PEO content reduced with degradation time because the PEO segment was broken down and dissolved in the medium during degradation. © 2000 Society of Chemical Industry     

Advances in the science and technology of paints, inks and related coatings: 2005

Summary  This review summarises the developments in adhesion, VOC emissions, coatings, transparent conductive coatings, hybrid organic-inorganic coatings, UV curing, biocidal coatings, paints, weathering, wood coatings, surface treatment of concrete, metal corrosion, pigments, film formation, printing, modelling fluid flow in printing, dot gain and inkjet printing reported inSurface Coatings International Part B: Coatings Transactions,88, 2005.     

助剂对常温固化FEVE氟碳涂料耐酸碱性能的影响

本文通过实验对比了不同助剂对常温固化型FEVE氟碳涂料涂膜耐酸碱性能的影响,并且分析了其主要原因.     

Mechanical properties of thin and thick coatings applied to various substrates. Part II. Young's modulus determination of coating materials*

To determine Young's modulus of coating materials when they are applied to substrates, theoretical and experimental analyses are performed. Significant residual stresses are generated within thin and thick coatings applied to substrates. As a result of these stresses, the bi-material strip assumes a certain curvature. The curved beam theory was used to establish the equivalent bending stiffness of bi-layer materials as functions of (a) the initial radius of curvature generated by residual stresses, (b) the mechanical radius of curvature during flexure testing, and (c) mechanical (Young's moduli) and geometrical (widths and thicknesses) characteristics of bi-layered systems. The relevant expression was transformed to a second- or third-order equation in order to calculate Young's modulus of the coating undergoing residual stresses (using models developed in Part I and by Stoney, Röll, and Inoue).     

Study of the partial wetting morphology in polylactide/poly[(butylene adipate)‐co‐terephthalate]/polyamide ternary blends: case of composite droplets

The prediction of the morphology of ternary polymer blends requires a good knowledge of the values of the three interfacial tensions. We selected three polymers, either biobased or biodegradable, polyamide (PA), poly[(butylene adipate)‐co‐terephthalate] (PBAT) and polylactide (PLA), and we accurately measured their interfacial tensions using the retraction method, varying the molar mass or inverting the phases. The following values of interfacial tension were obtained: γ_PBAT/PLA = 3.3 ± 0.7 mN m^?1, γ_PA/PLA = 5.6 ± 0.3 mN m^?1 and γ_PBAT/PA = 3.0 ± 0.4 mN m^?1. These values were used to calculate the spreading coefficients giving rise to two negative coefficients and one coefficient close to zero. Ternary blends with various compositions, two different levels of viscosity for PBAT and different processing conditions were prepared. There was a very good agreement between the predictions of the spreading theory, when using the values of interfacial tension of the right order of magnitude, and the observed morphologies, whatever the polymer serving as a matrix. When PLA or PBAT was chosen as the matrix, the ternary blend morphology was composed of composite droplets, presenting a partial wetting morphology, dispersed in the polymer matrix. This morphology was observed whatever the composition, the viscosity of the PBAT phase and the processing conditions. A further calculation of the free energy confirmed this morphology. The formation process of this semi‐encapsulated morphology was observed during blending. © 2018 Society of Chemical Industry     

Swelling and hydrolytic degradation behaviour of pH‐responsive hydrogels of poly[(N‐isopropylacrylamide)‐co‐(methacrylic acid)] crosslinked by biodegradable polycaprolactone chains

BACKGROUND: Stimuli‐responsive hydrogels are typically obtained from non‐biodegradable monomers. The use of biodegradable crosslinkers can overcome this limitation. In this context, the main aim of this work was to use modified polycaprolactone as a crosslinker in the preparation of pH‐responsive hydrogels based on N‐isopropylacrylamide and methacrylic acid to give poly[(N‐isopropylacrylamide)‐co‐(methacrylic acid)] (P(N‐iPAAm‐co‐MAA)). RESULTS: Poly(caprolactone) dimethacrylate macromonomer was synthesized and successfully employed as crosslinker with various ratios in the synthesis of well‐known pH‐responsive hydrogels of P(N‐iPAAm‐co‐MAA). The swelling properties of these degradable hydrogels were investigated. They practically do not swell at pH = 2, but exhibit a very high swelling capacity in distilled water and in solutions of pH = 7. In addition, degradation studies at pH = 12 showed that the hydrolysis of the ester groups in the polycaprolactone chains produces, after a relatively short time, the total solubilization of the polymer chains. CONCLUSION: The hydrogels under study have certain characteristics that could make them good candidates for use as matrices in controlled drug delivery. On the one hand, they do not swell in acid pH solution (stomach conditions) but they swell extensively at neutral pH. On the other hand, they became rapidly water soluble following degradation. Copyright © 2009 Society of Chemical Industry     

Mixed poly(methyl methacrylate)/poly(ethylene glycol) brushes: Study of switching behavior in selective solvent

The mixed polymer brushes composed of two incompatible polymers, poly(methyl methacrylate) and poly(ethylene glycol), were successfully synthesized via a sequential grafting to method, which was confirmed by water‐contact angle and ellipsometric measurements. The resulted mixed polymer brushes could undergo conformational rearrangements upon exposure to different selective solvents, and then the lateral segregation in nonselective solvent and perpendicular segregation in selective solvent happened. As a result, the mixed polymer brushes exhibited the ripple morphology and dimple morphology in corresponding solvent, respectively, and which led to changes in water‐contact angle and surface composition as a function of bulk composition of the mixed polymer brushes. Moreover, the switching properties as the surface composition, wettability and topographical images could occur in a controlled and reversible fashion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Regulating the pore structure of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) oxidized cellulose membranes: impact of drying method and organic solvent processing

Cellulose‐based membrane is a satisfactory candidate for the separator of lithium‐ion batteries due to its renewability, abundant pore structure and outstanding thermal–chemical stability. In this study, 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) oxidized cellulose fiber (TOCF) membranes with different oxidation degrees were prepared. Membranes with high oxidation degree are faced with a pore closure issue, resulting in low porosity. In order to improve the pore structure, the TOCF membranes were dried differently through air drying, vacuum drying and freeze drying. Furthermore, air‐dried membranes were processed by three organic solvents – n‐butyl alcohol, carbon tetrachloride and n‐heptane. The physical properties, pore structure characteristics, mechanical properties and the electrochemical performance of the membranes were measured and characterized. From the results, freeze drying is found to provide the highest porosity and mean pore diameter. Unfortunately, Young’s modulus of the freeze‐dried membranes is the smallest as well. However, membranes processed by n‐butyl alcohol have weak tensile properties. Compared to non‐processed membranes, membranes processed by organic solvents present better pore structure and significantly better electrochemical performance. With all properties considered, TOCF membranes processed by carbon tetrachloride or n‐heptane are qualified for serving as battery separators as they possess improved pore structure, enhanced Young’s modulus, considerable tensile strength and improved electrochemical properties. © 2020 Society of Chemical Industry     

Phase behavior of the ternary system solvent: poly(γ-benzyl L-glutemate) and polystyrene

Summary Phase equilibria were investigated at 80°C for a ternary system involving a solvent benzyl alcohol, a rodlike polymer poly(-benzyl L-glutamate) (PBLG), and a flexible polymer polystyrene (PS). The fairly dilute solution of the two polymers was isotropic and monophasic. At greater concentrations, it was separated into two isotropic phases. Above an even higher critical concentration of the two polymers, three phases, a cholesteric (A₁) and two isotropic phases (I₁ and I₂), coexisted at equilibrium. PBLG was contained exclusively in the phases A₁ and I₁, while PS was in the phase I₂. The more concentrated solution was separated into a cholesteric phase and an isotropic phase. The latter contained PS but excluded PBLG, These features were discussed on the ground of the Flory theory by considering the polymer compatibility.     

外墙乳胶漆涂膜“泛白”原因及解决措施

针对外墙乳胶漆施工后由涂料浮色、墙体泛碱、表面活性剂渗出及墙体渗水引起的涂膜"泛白"弊病进行了分析,并提出了相应的解决办法。     

Supercritical CO2 and low-pressure solvent extraction of mango (Mangifera indica) leaves: Global yield,extraction kinetics,chemical composition and cost of manufacturing

Low-pressure solvent extraction (LPSE) and supercritical fluid extraction (SFE) were used to obtain extracts from mango (Mangifera indica) leaves. Kinetics curves were determined for both methodologies. The extracts chemical compositions and manufacturing costs were determined for both processes. Global yield isotherms for SFE process were determined at 10–40 MPa and 313–323 K. The highest yield was 2.24% at 30 MPa and 323 K; the LPSE yield (9.3%) was almost three times higher than that of SFE (3.6%). Thin layer chromatography showed that mango leaves extracts have several classes of compounds as alkaloids, flavonoids and terpenoids, recovered by both methods. The cost of manufacturing (COM) mango leaves extracts were US$ 32/kg and US$ 92/kg for LPSE and SFE, respectively.     

Delaying the onset of macrogelation for the synthesis of branched and star-like polymers via conventional free-radical polymerisation: Binary solvent effects and incorporation of surfmers

It is known that the preferential solvation and conformation of a polymer in a solvent mixture are functions of the polymer's molecular weight and the solvent qualities. This paper demonstrates that these relationships can be exploited to delay the onset of macrogelation for branched poly(methyl methacrylate/ethylene glycol dimethacrylate) (p(MMA/EGDMA)) polymers and star-like poly(methyl acrylate/ethylene glycol dimethacrylate) (p(MA/EGDMA)) polymers synthesised via conventional free-radical polymerisation (CFRP) in a binary solvent mixture (consisting of a good solvent and a precipitant for the polymer). The gelation limits of the MMA/EGDMA and MA/EGDMA polymerisations in a methyl ethyl ketone (MEK)/heptane binary solvent mixture can be extended to regions of higher monomer concentration with increases in polymer yield between 13 and 50 ± 5 w/w% for the p(MMA/EGDMA) system and between 8 and 19 ± 6 w/w% for the p(MA/EGDMA) system across the gelation boundary. Thus, a facile method of increasing the concentration of batch reaction mixtures by the simple addition of small amounts of precipitant into the reaction solutions is presented. Furthermore, the gelation limits of both polymerisation systems in the binary solvent mixtures were further extended with increases in polymer yield between 11 and 17 ± 4%w/w for the p(MMA/ODA/EGDMA) system and between 8 and 20 ± 5%w/w for the p(MA/VS/EGDMA) system by the respective incorporation of octadecyl acrylate (ODA) and vinyl stearate (VS) surfmers into the polymers, demonstrating the application of steric hinderance to shield the propagating polymers from excessive cross-linking reactions.     

Imprinted microspheres and nanoparticles with diclofenac sodium: effect of solvent on the morphology and recognition properties

To achieve suitable properties for specific applications, we synthesized diclofenac sodium (Ds) imprinted polymer beads with controllable size in the range of around 145 nm to 3 µm in diameter by the precipitation polymerization method using methacrylic acid as functional monomer, trimethylolpropane trimethacrylate as crosslinker and azobisisobutyronitrile as initiator. We analyzed the effect of the porogenic solvent on the morphology and recognition of particles. SEM analysis showed some dissimilarity in appearance of the imprinted polymers. The specific surface areas were 246 m² g^–1 and 260 m² g^–1 for imprinted polymers prepared in a mixture of tetrahydrofuran/acetonitrile (MIP1) and tetrahydrofuran/toluene (MIP2) respectively, which were in good agreement with the binding capacities of 150.4 mg g^–1 for MIP1 and 280.4 mg g^–1 for MIP2, but the imprinted nanoparticles with a specific selectivity factor of 1.5 had a better recognition property to Ds than the analog template meclofenamate sodium monohydrate (Ms) and also faster rebinding kinetics or greater accessibility of Ds. Finally the imprinted microspheres were successfully applied as a solid phase extraction sorbent for the extraction of Ds from human urine with limits of detection and quantification of 0.085 mg L^–1 and 0.227 mg L^–1, respectively. © 2013 Society of Chemical Industry