Preparation and Properties of Ethylene Vinyl Acetate (EVA)/Organoclay/Compatibilizer Nanocomposites: Effects of Organoclay Loading and Methyl Ethyl Ketone

Ethylene vinyl acetate (EVA)/organoclay/compatibilizer nanocomposites were produced using a melt compounding technique in an internal mixer, Haake Rheometer, at 120°C and 50 rpm rotor speed. Effects of organoclay loading (from 2 to 10 phr—parts per hundred of resin and methyl ethyl ketone (MEK), used as a compatibilizer, on the processing properties, tensile properties, morphology, thermal degradation, and water absorption behavior of EVA/organoclay nanocomposites were studied. Results indicate that the presence of organoclay increase the processing torque, tensile properties, thermal degradation, and resistance to water absorption. The optimum organoclay loading was achieved at 2 phr. This was caused by the dispersion state of individual silicate layers (intercalation/exfoliation) in EVA matrix. The intercalation/exfoliation structure affects the properties of EVA/organoclay nanocomposites as evidenced from the morphology studies such as x-ray diffraction (XRD) and transmission electron microscopy (TEM) evaluation. The addition of MEK has the ability to improve the tensile properties, thermal degradation, and slightly reduces the resistance of water permeation of EVA/organoclay nanocomposites. The enhanced properties were seen as a result of the better matrix and filler interaction. The EVA/organoclay/MEK nanocomposites shows better intercalation/exfoliation of individual silicate layers in the EVA matrix as indicated by TEM. Moreover, the XRD evaluation shows that intercalation/exfoliation of the organoclay was formed in the EVA matrix.     

Synthesis and Characterization of Maize Starch Acetates and its Biodegradable Film

Starch acetates (SA) were synthesized by maize starch reacting with acetic acid/acetic anhydride, using sulfuric acid as catalyst. The biodegradable films were produced by thermal gelatinization of starch suspensions blending raw starch or SA with different degree of esterification (DS) and polyvinyl alcohol (PVA). Fourier transform infrared spectrogram (FT-IR) data showed acetate was introduced into the molecule chain of starch. Different structure of aggregation supported between the modified starch and the raw starch was determined by the scanning electron microscopy (SEM). Differential scanning calorimetry indicated SA glass transition temperature reduced with increasing of its DS. X-ray diffraction pattern of SA revealed the crystallinity of chain starch was destroyed, forming many completely even amorphous areas. SEM studies showed that amorphous was raised with DS of starch acetates. The mechanical and hydrophobic properties of the films were better than those of raw starch/PVA. In 50 days outdoor soil burial biodegradable experiment in summer, the weight loss of the films was almost 50%.     

Experimental investigation and prediction of bonding strength of Oriental beech (Fagus orientalis Lipsky) bonded with polyvinyl acetate adhesive

Adhesive bond strength of solid wood plays a key role in the efficient use of wood in a large number of engineering applications. In this study, the effects of amount of adhesive, pressing pressure, and pressing time on bonding strength of beech wood bonded with polyvinyl acetate adhesive were investigated and predicted by developing an artificial neural network (ANN) model. Experimental results have showed that bonding strength of wood samples increased generally by increasing amount of adhesive, pressing pressure, and pressing time. Besides, ANN analysis has yielded highly satisfactory results. The designed neural network model allows predicting the bonding strength of wood samples with mean absolute percentage error of 2.454% and correlation coefficient of 97.8% for testing phase. It is clear from the results that the model has a good learning and generalization ability. This model therefore can be used to predict bonding strength of beech samples bonded with polyvinyl acetate adhesive under given conditions. Consequently, this study provides beneficial insights for practitioners in terms of the safe and efficient use of wood as an engineering material in applications related to the strength of the bond between wood and adhesive.     

Effect of a binder system on the low-pressure powder injection moulding of water-soluble zircon feedstocks

Micronized natural zircon sand powders were used as a raw material to conduct low-pressure powder injection moulding (LPPIM) processes. PIM could lead to new technological applications for this mineral, which has very stable dimensional behaviour with changing temperature. Zircon powders that have unconventional attributes for PIM (in terms of size and morphology) were mixed with poly(ethylene glycol) (PEG) based binders. Combinations of this water-soluble substance with different polymers, including low-density polyethylene (LDPE) and several types of acetate butyrate celluloses (CAB), were investigated. The influence of acetyl, butyryl and hydroxyl groups on the behaviour of the created feedstocks at different process stages and on the final piece properties were studied. The higher affinity of CAB with PEG and zircon powders compared with LDPE could result in improved densification and properties, but the butyryl, acetyl and hydroxyls groups affect the processability of these feedstocks.     

Measurement and correlation of the solubility of two steroid drugs in supercritical carbon dioxide using semi empirical models

The solubilities of desoxycorticosterone acetate (DA) and clobetasole propionate (CP) in supercritical carbon dioxide (SC-CO₂) were measured at temperature ranging from (308 to 348) K and pressures from (12.2 to 35.5) MPa using a static method. The mole fraction solubilities ranged from 10⁻⁷ to 13.93 × 10⁻⁵. The crossover region was observed for DA and CP at 24.3 and 25.3 MPa, respectively. Solubility data were correlated using four semi-empirical density-based models (Chrastil, Bartle, Kumar, Johnston (K–J) and Mendez-Santiago and Teja (M–T) models). The average absolute relative deviations (AARD%) ranged from 9.3 to 13.6; 8.9 to 11.9; 6.5 to 10.3 and from 10.4 to 13.4 for Chrastil, Bartle, K–J and M–T models, respectively. A comparison among the four models revealed that the K–J model gave much better correlation of the solubilities in comparison with other models. Using the correlation results, the heat of drug–CO₂ solvation and that of drug vaporization was separately approximated in the range of −24.2 to −24.5 and 63.8 to 64.8 kJ mol⁻¹. The correlation results showed good agreement with the experimental data.     

Experimental Measurements and Correlations Isobaric Vapor-Liquid Equilibria for Water + Acetic Acid + Sec-butyl Acetate at 101.3 kPa

Isobaric vapor-liquid equilibrium(VLE) data for acetic acid+sec-butyl acetate and water+acetic acid+sec-butyl acetate systems were determined at 101.3 kPa using a modified Rose type. The nonideality of the vapor phase caused by the association of the acetic acid was corrected by the chemical theory and Hayden-O’Connell method. Thermodynamic consistency was tested for the binary VLE data. The experimental data were correlated successfully with the Non-Random Two Liquids (NRTL) model. The Root Mean Square Deviation (RMSD) of the ternary system was 0.0038. The saturation vapor pressure of sec-butyl acetate at 329 to 385 K was measured by means of two connected equilibrium cells. The vapor pressures of water and sec-butyl acetate were correlated with the Antoine equation. The binary interaction parameters and the ternary VLE data were obtained from this work.     

Synthesis and Characterization of Molecularly Imprinted Polymer Membrane for the Removal of 2,4-Dinitrophenol

Molecularly imprinted polymers (MIPs) were prepared by bulk polymerization in acetonitrile using 2,4-dinitrophenol, acrylamide, ethylene glycol dimethacrylate, and benzoyl peroxide, as the template, functional monomer, cross-linker, and initiator, respectively. The MIP membrane was prepared by hybridization of MIP particles with cellulose acetate (CA) and polystyrene (PS) after being ground and sieved. The prepared MIP membrane was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The parameters studied for the removal of 2,4-dinitrophenol included the effect of pH, sorption kinetics, and the selectivity of the MIP membrane. Maximum sorption of 2,4-nitrophenol by the fabricated CA membrane with MIP (CA-MIP) and the PS membrane with MIP (PS-MIP) was observed at pH 7.0 and pH 5.0, respectively. The sorption of 2,4-dinitrophenol by CA-MIP and PS-MIP followed a pseudo–second-order kinetic model. For a selectivity study, 2,4-dichlorophenol, 3-chlorophenol, and phenol were selected as potential interferences. The sorption capability of CA-MIP and PS-MIP towards 2,4-dinitrophenol was observed to be higher than that of 2,4-dichlorophenol, 3-chlorophenol, or phenol.     

醋酸乙烯市场前景与装置建设的几点思考

介绍了国内外醋酸乙烯供需现状和市场前景,提出了关于醋酸乙烯装置建设的几点思考。     

化学法测定醋酸正丁酯含量方法的改进

本文用常温静止法替代沸水浴回流法测定醋酸正丁酯含鲢,将两种化学法测定结果与气相色谱法进行了平行对照。分析了化学方法的精密度、准确度。改进后的方法应用于生产控制过程,简化了操作,又节约水、电,降低了测定成本。     

改善聚醋酸乙烯酯胶膜耐水性的方法

分析了聚醋酸乙烯耐水性差的原因,归纳了其改性方法。