自干型环氧丙烯酸改性水性醇酸树脂的制备与性能

在酯化反应中后期加入环氧树脂E-20,合成环氧改性醇酸树脂后,再加入苯乙烯(St)、甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)和甲基丙烯酸(MAA)进行共聚接枝,获得了自干型环氧丙烯酸改性水性醇酸树脂。分析了加入环氧树脂时酸值、环氧树脂用量、丙烯酸单体总用量、各单体用量比例、引发剂过氧化苯甲酰(BPO)用量和反应温度等对产物性能的影响。结果表明:在酸值为35~40 mg KOH/g时加入8%~12%E-20,丙烯酸类单体总量为20%[其中w(St)∶w(MMA)=1∶1,w(软单体)∶w(硬单体)=1∶3],BPO用量为单体量的6%,温度控制在115°C,得到的改性树脂水分散性良好,干燥速度快,漆膜硬度、附着力、耐水性和耐盐水性等性能均优于未改性醇酸树脂漆膜。     

Electrochemical stability and surface analysis of a new alkyd paint with low content of volatile organic compounds

This paper presents the results regarding the electrochemical stability and surface analysis of a new alkyd paint with low content of volatile organic compounds in comparison with a conventional alkyd paint. The alkyd films were realized on carbon steel substrate. Dry films thickness in 30–35 μm range was obtained. The experimental tests were carried out in 3% NaCl solution at the 25 °C temperature. The electrochemical techniques (electrochemical impedance spectroscopy (EIS), potentiodynamic and Tafel polarization) and surface analysis techniques (AFM, SEM, EDX) were used to evaluate protective properties of the tested paint films. The correlation of all experimental results established that the new alkyd paint with low content of volatile organic compounds presents better protective performances and lower permeability than conventional alkyd paint. AFM, SEM and EDX indicated a compact, homogenous, non-porous and adherent coating.     

Preparation and properties of urethane/acrylate composite by emulsion polymerization technique

Aqueous polyurethane–acrylic hybrid emulsions were prepared by semibatch emulsion polymerization of a mixture of acrylic monomers (styrene, butyl acrylate and acrylic acid) in the presence of polyurethane dispersion. Equivalent physical blends were prepared by mixing acrylic emulsion and polyurethane dispersion. The weight ratio between acrylic and polyurethane components was varied to obtain enhanced performance properties and microphase structure of hybrid latexes. The synthesized emulsion hybrids and physical blends were characterized by fourier transform infrared spectroscopy, thermogravimetric analysis. The experimental results indicate better acrylic–polyurethane compatibility in hybrid emulsions than in physical blends, resulting in improved chemical and mechanical properties. The blend ratio 50:50% (w/w) exhibited synergistic effects between the two polymers and revealed remarkable improvement in various coating properties over other blend ratios and the individual resin components.     

Synthesis and properties of PDMS modified waterborne polyurethane–acrylic hybrid emulsion by solvent-free method

A new type of polysiloxane modified polyurethane–acrylic hybrid emulsion was synthesized by solvent-free method and the polysiloxane was introduced into the soft segment of polyurethane chains using dihydroxybutyl-terminated polydimethylsiloxane (PDMS). The formed film from the hybrid emulsion could provide obviously higher water-resistance property. The preparation technologies such as the content of carboxy group and acrylic monomer, the rate and the time of emulsification were discussed systematically. The chain structure and the particle size were confirmed by the analysis of Fourier transform infrared spectroscopy and transmission electron microscopy, respectively. The effect of PDMS content on the water resistance and the mechanical property were investigated by absorbed water ratio, water contact angle and dynamic mechanical measurement.     

Preparation and properties of urethane alkyd based on a castor oil/jatropha oil mixture

Castor oil is the only major natural vegetable oil that contains a hydroxyl group and so it is widely used in many chemical industries, especially in the production of polyurethanes. In this work, castor oil was interesterified with jatropha oil and the product was subsequently reacted with toluene diisocyanate to obtain urethane alkyd. The prepared urethane alkyd was characterized and its properties were determined and compared with those of the conventional (glycerol/jatropha oil) and commercial urethane alkyds. The castor oil/jatropha oil-based urethane alkyd had a lower molecular weight and viscosity, a slightly lower hardness and greatly longer drying time than the conventional and commercial urethane alkyds, but otherwise the film properties were broadly similar, including being very flexible, with an excellent adhesion and high impact resistance. In addition, they also exhibited excellent resistance to water and acid.     

The formulation and study of the thermal stability and mechanical properties of an acrylic coating using chicken eggshell as a novel bio-filler

The objective of this study was to evaluate the effect of chicken eggshell (ES) as a bio-filler on the adhesion strength and thermal stability of acrylic coatings. The influence of different particle sizes of ES on the performance of acrylic coatings was compared with commercial calcium carbonate filler by using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and pull-off type equipment. The surface morphologies of the coatings were characterized through field emission scanning electron microscopy (FESEM). The resistance of the coating was also investigated using water immersion and freeze–thaw tests. Morphological studies revealed that the ES filler was well-distributed in the polymer matrix. Furthermore, it was observed that the adhesion strength, thermal properties, water and freeze–thaw resistance of the coating improved with decrease in particle size of ES filler. Overall, the best results were obtained from using ES bio-filler with the smallest particle, although the particle size was bigger than that of commercial calcium carbonate. The improvement in the properties of the coating was attributed to the even distribution of ES particles and better ES/matrix interface.     

Synthesis and properties of alkoxysilane-functionalized urethane oil/titania hybrid films

In this study, alkoxysilane-functionalized urethane oil/titania (AFUO/titania) hybrid films were synthesized by sol–gel method. For this purpose, alkoxysilane-functionalized urethane oil (AFUO) was first produced by the reaction of 3-aminopropyltriethoxysilane (APES) and partial glyceride (PG) mixture with toluene diisocyanate (TDI). Then, this intermediate was further reacted with titanium isopropoxide (TIP) by sol–gel process in thin films applied on a glass substrate. TIP content of the hybrid films were varied in the range of 5–20 wt.% in order to investigate optimum amount of TIP in view of film properties. The characterization of the hybrid films were done by FTIR, DSC, TGA and SEM analyses. FTIR and DSC analyses indicated the existence of Ti–O–Si bond. Film properties for coating purposes such as flexibility, adhesion, hardness, water, alkali and acid resistances were determined. Hybrid composite films showed better film properties in comparison with classical urethane oil.     

Effect of microstructure of acrylic copolymer/terpolymer on the properties of silica based nanocomposites prepared by sol-gel technique

Acrylic copolymers/terpolymers with different comonomer contents were prepared by solution polymerization. Copolymers/terpolymers-silica hybrid composites were synthesized by acid catalyzed sol-gel technique using tetraethoxysilane (TEOS) as silica precursor. Microstructure of the copolymers and the terpolymers was analyzed by C¹³ nuclear magnetic resonance and Fourier transform infrared (FTIR) spectroscopy. The hybrid composites were characterized by scanning electron microscopy (SEM), FTIR, thermogravimetry, dynamic mechanical thermal analysis (DMTA) and their mechanical properties. The results showed that an increase in hydrophilicity of the polymer matrix and the ratio of ethyl to butyl acrylate, and incorporation of acrylic acid as termonomer helped in finer dispersion of silica and prevented macrophase separation. There was no evidence of chemical interaction between the polymer and the dispersed silica phase. Dynamic mechanical thermal analysis indicated mechanical reinforcement within the hybrid composites. As a result, these composites demonstrated superior tensile strength and tensile modulus with increasing proportion of TEOS up to a certain level. At a particular TEOS concentration, the tensile properties improved with increasing hydrophilicity of the polymer matrix and acrylic acid modification. The mechanism for improvement in mechanical and dynamic mechanical properties of the hybrids was discussed.     

Effect of functional monomer on the stability and film properties of thermosetting core-shell latexes

Functionalized core-shell latexes were prepared by copolymerization of butyl acrylate and methyl methacrylate with 2-hydroxyethyl methacrylate (HEMA) or methacrylic acid (MAA), which were added during the first or second stages of polymerization, respectively. The HEMA and MAA concentrations were increased while the equivalent ratio of functional groups remained constant. Colloidal stability, particle size, particle size distribution, film properties and morphology were studied as functions of functional monomer content. The upper limit functionality content was limited by the stability of the system during synthesis. A bimodal particle size distribution was observed for high concentrations of functional monomers. Increase in carboxyl and hydroxyl functionalities improved tensile strength and modulus for un-crosslinked films, and generally higher tensile strength, tensile modulus and storage modulus at high temperature were obtained after the functional latexes were crosslinked with a cycloaliphatic diepoxide.     

Sol-gel derived organic-inorganic hybrid from trialkoxysilane-capped acrylic resin and titania: effects of preparation conditions on the structure and properties

Homogeneous organic-inorganic hybrid materials with high performance were successfully prepared by mixing (3-methacryloxypropyl)trimethoxysilane (MPMS) capped acrylic resin with titania synthesized by sol-gel approaches. The effects of the titania content, the amount of water and nature of catalysts in the sol-gel as well as the ratios of mixed solvents of butyl acetate and ethanol on the structures and properties of the hybrid materials were studied. Higher titania content, larger amount of water and base catalysis in the sol-gel process, as well as the solvent with higher ratio of butyl acetate to ethanol for the hybrids caused larger size and less open structure of titania phase. The hardness, elastic modulus, thermal stability and refractive index for the hybrid materials improved dramatically with increasing titania content. In general, better prosperities, especially mechanical properties, were achieved for the hybrid prepared under lower water content, pH values (such as acid catalysis) and m_B/m_E ratio.     

Fabrication and photocatalytical enhancement of ZnO-graphene hybrid using a continuous solvothermal technique

A continuous solvothermal approach is presented for fabricating ZnO-graphene hybrid nanoparticles with enhanced photocatalytic activity. The approach combines continuously delivering the graphene ethanol solution and the ZnO precursor ethanol solution simultaneously into the reactor. It takes only seconds to forming ZnO-graphene composites. The structure and morphology of the fabricated samples are characterized via X-ray diffraction, scanning electron microscopy, transmission electron microscope and scanning transmission electron microscope. Two types of the hybrid composites, a film-grain and a cobweb composite, are obtained at the different concentrations of the precursor while the temperature, the pressure and the resident time are 160 °C, 7 MPa, and 30 s, respectively. The synthesis mechanism is illustrated. The resultant hybrids exhibit excellent photocatalytical activity in degrading methyl orange dye in water. The degradation rate reaches almost 100% in 200 min. The degradation increases 30% compared with the bare ZnO. This enhanced photocatalytical performance of the ZnO-graphene hybrids attributes to the rapidly transfer of the photo-generated electrons from the surface of the catalyst to the graphene, preventing the photo-generated electron–hole pairs from the recombination. We believe that this continuous solvothermal approach can be a general way to prepare metal oxide-graphene composites with unique properties.     

Jatropha curcas oil based alkyd/epoxy resin/expanded graphite (EG) reinforced bio-composite: Evaluation of the thermal,mechanical and flame retardancy properties

Bio-composites were prepared from blends of Jatropha curcas oil based alkyd and epoxy resin with different weight percentage of expanded graphite (EG). The effect of EG loading on the thermal, mechanical, flame retardancy and water absorption properties of the bio-composites were studied. Significant improvement in thermal and mechanical properties was observed with 5 wt% EG loading. The prepared bio-composites were characterized by fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray diffractometry and tensile strength measurement. Morphological study showed the homogeneous dispersion of the EG sheets in the resin matrix. Limiting oxygen index (LOI) of the bio-composites showed a noticeable improvement in flame retardancy in comparison to neat blend of alkyd and epoxy resin. In vitro degradation of the bio-composites showed low degradation in phosphate buffer solution (pH 7.4).     

Optimization of the supercritical fluid coextraction of oil and diterpenes from spent coffee grounds using experimental design and response surface methodology

The reported work aimed at the optimization of operating conditions of the supercritical fluid extraction (SFE) of spent coffee grounds (SCG) using pure or modified CO₂, with particular emphasis on oil enrichment with diterpenes like kahweol, cafestol and 16-O-methylcafestol. The analysis comprised the application of Box–Behnken design of experiments and response surface methodology, and involved three operating variables: pressure (140–190 bar), temperature (40–70 °C) and cosolvent (ethanol) addition (0–5 wt.%). The best conditions to maximize total extraction yield are 190 bar/55 °C/5 wt.% EtOH, leading to 11.97% (g_oil/100 g_SCG). In terms of the concentration of diterpenic compounds in the supercritical extracts, the best operating conditions are 140 bar/40 °C/0 wt.% EtOH, providing 102.90 mg g⁻¹_oil. The measurement of extraction curves near optimized conditions (140 bar/55 °C/0 wt.% EtOH and 190 bar/55 °C/0 wt.% EtOH) confirmed the trends of the statistical analysis and revealed that SFE enhances diterpenes concentration by 212–410% at the expenses of reducing the extraction yield between 39% and 79% in comparison to n-hexane extraction.     

Optimization of UV curable acrylated polyester-polyurethane/polysiloxane ceramer coatings using a response surface methodology

Dual UV and moisture curable acrylated polyester, organic/inorganic hybrid coatings were prepared using a coupling agent and tetraethylorthosilicate (TEOS) oligomers. An acrylated polyester resin based on adipic acid, neopentyl glycol, trimethylolpropane, and acrylic acid was synthesized. TEOS oligomers were prepared through the hydrolysis and condensation of TEOS with water and 3-(triethoxysilyl)propylisocyanate (TEOSPI) was used as the coupling agent between organic and inorganic phases. Trimethylolpropane triacrylate (TMPTA) was used as a reactive diluent. The formulations were cured into films by utilizing UV, followed by moisture curing. The resultant coatings were evaluated in terms of tensile and fracture toughness properties by using ANOVA. Effects of the TEOS oligomers, TEOSPI, and TMPTA on the free radical UV polymerization kinetics were also investigated. The experiments were planned according to the three-factor, three-level Box-Behnken design. Reaction kinetics, fracture toughness, and tensile properties were evaluated in terms of the concentrations of TEOS oligomers, TEOSPI, and TMPTA concentrations. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 25–27, 2004, in Chicago, IL.     

General optimization strategy of simulated moving bed units through design of experiments and response surface methodologies

The optimization of simulated moving bed (SMB) units is often performed through detailed phenomenological models and require extensive computation time. Hence several optimization methods like the Triangle Theory, and the concept of separation volume have been proposed. However, they do not provide accurate results, when mass transfer limitations are significant, or require a large number of simulations.In this work, a combined Design of Experiments and Response Surface Methodology (DoE-RSM) approach is proposed for SMB optimization, aimed at providing good results with simplicity and reduced number of simulations. The separation of trans-stilbene oxide enantiomers is selected as case study in order to compare DoE-RSM with previous approaches. In the whole, accurate results are obtained with a few number of simulations, allowing for purities above 99.60% for both enantiomers, and productivity of 65.41 kg/(m³_adsorbent day). The versatility of DoE-RSM tool is also discussed, emphasising their advantages and general applicability.     

Effects of Process Parameters on the Skin/Core Distribution in Co-Injection: Experiments and Simulations Using a Simple Geometry

In this work the effect of processing parameters on core breakthrough and material distribution during co-injection in a model mould has been studied. PMMA was used for the skin and ABS for the core. To identify the influences of the core volumetric fraction, its injection rate and temperature and the skin injection temperature a series of computer simulations and experimental tests were performed according to the design of experiments statistical approach. The results of statistical analysis performed on data coming from experiments and simulations are consistent, even if simulations overestimate the ABS content at which the breakthrough takes place.     

Optimization of the technological properties of porcelain tile bodies containing rice straw ash using the design of experiments methodology

This study examines the effects of replacing fluxing and filler materials with rice straw ash (RSA) in manufacturing porcelain stoneware tile, using the design of experiments (DOE) methodology. The results of the characterization were used to obtain statistically significant, valid regression equations, relating the technological properties of the dried and fired test pieces to the raw materials content in the unfired mixtures. The regression models were analysed in relation to the X-ray diffraction and scanning electron microscopy results and used to determine the most appropriate combinations of traditional raw materials and RSA to produce porcelain stoneware tiles with specific technological properties. The studied range of tile body compositions: clay (40 wt%), feldspar (20–50 wt%), feldspathic sand (5–20 wt%), and RSA (0–25 wt%) was shown to be appropriate for porcelain stoneware tile manufacture.     

From dynamic response surface models to the identification of the reaction stoichiometry in a complex pharmaceutical case study

The dynamic response surface methodology (DRSM) (Klebanov and Georgakis, Ind Eng Chem Res. 2016;55(14):4022–4034) was proposed as a generalization of the classical response surface methodology (RSM). The power of DRSM is evaluated here in a blind test against a complex pharmaceutical process containing 10 observed species involved in eight reactions. The obtained DRSM models, one for each species, accurately represented the time-varying concentrations of 8 of the 10 species. The DRSMs for two intermediate species suffered a bit from oscillatory behavior toward the end of the batch, due to their small concentration values and the polynomial-based model. These DRSM models greatly facilitated the application of target factor analysis (Bonvin and Rippin, Chem Eng Sci. 1990; 45(12): 3417–3426) correctly identifying six of the eight true reaction stoichiometries, whereas all six false reactions were rejected. In addition, the ability to distinguish true and false reaction stoichiometries was not affected by a less informative design of experiments (DoEs) than the original center composite design (CCD). © 2018 American Institute of Chemical Engineers AIChE J, 65: 1173–1185, 2019     

The effect of secondary nanofiller on mechanical properties and formulation optimization of HDPE/nanoclay/nanoCaCO3 hybrid nanocomposites using response surface methodology

Mechanical properties were evaluated in high-density polyethylene (HDPE) containing plate-like nanoclay (NC) and particulate nano calcium carbonate (nCaCO₃). A two-step melt mixing method was utilized to prepare nanocomposites withNC/nCaCO₃ hybrid content varying from 7 to 15 wt%. Optimization of the morphological, rheological and mechanical characteristics was carried out via Response Surface Methodology by considering nanofiller loadings and compatibilizer (PE-g-MA) content as independent variables. The findings revealed that a nanocomposite composed of 9 wt% PE-g-MA, 3.5 wt%NC, and 10 wt%nCaCO₃ was optimal. This composition exhibited 50% enhancement in Young's modulus and 8% improvement in yield strength over neat HDPE. Despite the reduced impact strength in all of the prepared nanocomposites, the incorporation ofnCaCO₃ prevented a sudden decrease in the toughness caused by the nanoclay. Further, the fracture behavior observed by scanning electron microscopy (SEM) images suggested that nCaCO₃ activated new toughening mechanisms.     

Parameter optimization for the oxidative coupling of methane in a fixed bed reactor by combination of response surface methodology and computational fluid dynamics

A resource and time saving method is introduced for optimizing fixed bed reactors by the combination of response surface methodology (RSM) and CFD simulation. This is demonstrated for the oxidative coupling of methane (OCM) based on the reaction kinetics by Stansch et al. (1997). Firstly, a parameter screening is performed to identify the power factors modified reaction time, heating temperature and CH₄ to O₂ ratio. Secondly, utilizing Central Composite Design, meta models for the most interesting responses are developed, i.e. C₂ selectivity and yield as well as CH₄ conversion. The statistical models describe the characteristics of the responses over a wide range. Thirdly, an optimization of C₂ yield is carried out using RSM. The maximum is detected to be approx. 14% and validated by three dimensional CFD simulations. In the investigated parameter space the optimized parameter conditions are found for a feed composition of 20% nitrogen, 26.7% oxygen, 53.3% methane (CH₄ to O₂ ratio of 2), a modified reaction time of 61 kg s/m³ and a heating temperature of 801.5 °C.