A dynamically distributed reactor model for identifying the flow fields in industrial loop propylene polymerization reactors

The use of distributed parameter model is becoming a common approach for simulating liquid–solid flow in loop polymerization reactors. However, there are still several issues with it. One of them is the absence of modeling of distributed pressure, as no thermodynamic state‐equation is incorporated into the model. In this work, inner pressure of the reactor was associated with temperature using a thermodynamic state‐equation for high‐pressure liquid. The thermodynamic state‐equation was solved together with a dynamically distributed reactor model based on the mass, energy, and momentum conservation as well as polymerization kinetics to predict the dynamic trajectories of component concentration, temperature, pressure, and bulk mass velocity in the reactor. Industrial steady‐state data were used for model validation. The application of the model was demonstrated by simulating the effect of recycle ratio on the above distributed reactor parameters. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Improved synthesis of a branched poly(ethylene imine)‐modified cellulose‐based adsorbent for removal and recovery of Cu(II) from aqueous solution

This study focuses on an improved synthesis of a branched poly (ethylene imine) (PEI)‐modified cellulose‐based adsorbent (Cell‐g‐PGMA‐PEI). We aim to improve the adsorbent capacity by reducing side reaction of epoxide ring opening during graft copolymerization of glycidyl methacrylate (GMA) onto cellulose which increases the content of epoxy groups, anchors to immobilize branched PEI moieties. FTIR spectra provided the evidence of successful graft copolymerization of GMA onto cellulose initiated by benzoyl peroxide (BPO) and modification with PEI. The amount of epoxy groups of Cell‐g‐PGMA was 4.35 mmol g^?1 by epoxy titration. Subsequently, the adsorption behavior of Cu(II) on cell‐g‐PGMA‐PEI in aqueous solution has been investigated. The data from the adsorption kinetic experiments agreed well with pseudo‐second‐order model. The adsorption isotherms can be interpreted by the Langmuir model with the maximum adsorption capacity of 102 mg g^?1 which was largely improved compared with the similar adsorbent reported. The dynamic adsorption capacity obtained from the column tests was 119 mg g^?1 and the adsorbent could be regenerated by HCl of 0.1 mol L^?1. Results indicate that the novel pathway for the synthesis of Cell‐g‐PGMA‐PEI exhibits significant potential to improve the performance of adsorbents in removal and recovery of Cu(II) from aqueous solution. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Structure and Dielectric Properties of Re0.02Sr0.97TiO3 (Re = La,Sm, Gd,Er) Ceramics for High‐Voltage Capacitor Applications

Rare–earth‐doped strontium titanate ceramics yielding the formula Re_0.02Sr_0.97TiO₃ (Re–ST, Re = La, Sm, Gd, Er) were prepared by solid‐state reaction route. All Re–ST ceramics had single cubic perovskite structure similar to pure SrTiO₃ (ST). The grain size of Re–ST ceramics dramatically decreased to 1–10 μm, depending on different rare‐earth elements, as compared to ~30 μm of pure ST. The relative dielectric constant of Re–ST ceramics (ε_r = 2750–4530 at 1 kHz) showed about 10–15 times higher than that of pure ST (ε_r = 300 at 1 kHz), whereas the dielectric loss of Re–ST ceramics still remained lower than 0.03 (at 1 kHz) at room temperature. Under 0–1.63 × 10⁶ V/m bias electric field testing conditions, the ε_r of Re–ST ceramics at room temperature changed within 14%. The P–E results indicated that the Re–ST ceramics were linear dielectrics. Together with their relatively high breakdown strength (E_b > 1.4 × 10⁷ V/m), the Re–ST ceramics could be very promising for high‐voltage capacitor applications. Meanwhile, the temperature stability of the ε_r of Re–ST ceramics was evaluated in a temperature range of ?60°C–200°C.     

Grain‐Boundary and Thermally Stimulated Current Characteristics of Y2O3‐Doped ZnO Varistor

The doping of rare‐earth oxides can greatly improve the electrical characteristics of ZnO varistors. Thermally stimulated current (TSC) characteristic test, capacitance voltage (C–V) characteristic test, scanning electron microscope (SEM) test, and voltage current (V–I) test were carried out to study the influence of Y₂O₃ content on the electrical properties of ZnO varistors in this study. The results show that the grain size decreases while the voltage gradient increases as the Y₂O₃ content is increased. The reaction of Y₂O₃ with other additives leads to the decrease in grain‐boundary defects, which accounts for the decrement of barrier height, donor density, and surface state density. The trap level and trapped charge of ZnO varistors decrease as the Y₂O₃ content is increased from 0.3 to 0.9 mol%, which means the shallow traps inside ZnO varistors reduce, and the Y₂O₃ additive can greatly improve the TSC characteristic of ZnO varistors.     

Double‐hydrophobic siloxane diblock copolymers: Synthesis,micellization behavior,and application as a stabilizer for silver nanoparticles

The double‐hydrophobic well‐defined polydimethylsiloxane‐block‐poly(methyl methacrylate) (PDMS‐b‐PMMA) diblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Their chemical compositions and the structure were investigated. The micellization behavior of the double‐hydrophobic diblock copolymers with equal block length was thoroughly studied. The results showed that their self‐assembly behavior was analogous to the star‐like micelles. Furthermore, the effect of temperature on the aggregates was investigated to verify that the resulting copolymer (PDMS‐b‐PMMA) was to some extent temperature sensitive. Till date, there have been few reports on the utilization of nonamphiphilic block copolymers to synthesize and confine metal nanoparticles in aggregates. In this study, we explored the role of double‐hydrophobic block copolymers as a mediator for organically dispersible silver nanoparticles (AgNPs) and it offered to be an effective stabilizer for preparing AgNPs. Besides, AgNPs generated in organic solvent is an important addition to the hitherto predominantly water‐based processes for producing nanoparticles inside the polymer surfactant. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Surface modification of multiwalled carbon nanotubes via gliding arc plasma for the reinforcement of polypropylene

To increase the applicability of multiwalled carbon nanotubes (MWCNTs), functional groups were generated on the generally inert surface of MWCNTs using gliding arc (GA) plasma. MWCNTs were modified using plasma polymerization with styrene (St) as monomer. The surface compositional and structural changes that occur on MWCNTs were investigated using FT‐IR, Raman spectroscopy, BET surface area, and elemental analysis. Dispersion of the treated MWCNTs in different solvents was evaluated. Transmission electron microscopy images showed that the plasma‐treated MWCNTs had a better dispersion than the untreated ones in nonpolar solvents. Subsequently, MWCNTs‐reinforced polypropylene (PP) composites were prepared by internal batch mixing with the addition of 1.0 wt % MWCNTs. The morphology of MWCNTs/PP nanocomposites was studied through scanning electron microscopy. Observations of SEM images showed that the plasma‐treated MWCNTs had a better dispersion than the untreated MWCNTs either on the composite fracture surfaces or inside the PP matrix. Moreover, the mechanical tests showed that the tensile strength and elongation at break were improved with the addition of polystyrene‐grafted MWCNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preliminary Study on Chicken Feather Protein–Based Wood Adhesives

Abstract

The objective of this preliminary study was to partially replace phenol in the synthesis of phenol-formaldehyde resin with feather protein. Feather protein–based resins, which contained one part feather protein and two parts phenol, were formulated under the conditions of two feather protein hydrolysis methods (with and without presence of phenol during hydrolysis), two formaldehyde/phenol molar ratios (1.8 and 2.0), and three pH levels (9.5, 10.5, and 11.5). Southern pine fiberboard bonded with feather protein–based resins was fabricated and bending strength, bending stiffness, internal bonding strength, and percent thickness swell were evaluated. Results indicated that the test parameters all significantly affected resin quality. The resin formulated with feather protein hydrolyzed in the presence of phenol, using a F/P ratio of 2.0, and at a pH of 10.5 performed as well as the neat PF resin. Based on our findings, feather protein is a potential cost-effective material for the production of PF-type adhesive resins.     

埃洛石复配阻燃剂对聚丙烯阻燃性能和力学性能的影响

用埃洛石、三聚氰胺作为阻燃剂,制备了无卤阻燃聚丙烯(PP)复合材料。通过氧指数(OI)、垂直燃烧、万能力学仪、扫描电镜分析研究了埃洛石复配阻燃剂对PP阻燃性能、力学性能的影响。结果表明:埃洛石复配阻燃剂可使PP复合材料通过UL94燃烧性能测试,在提高材料OI的同时,保持了其优良的力学性能。     

马来酸酐接枝聚乙烯对纸/塑/铝复合材料性能的影响

采用熔融共混法制备了纸/塑/铝复合材料,研究了马来酸酐接枝聚乙烯(PE-g-MAH)的添加量对纸/塑/铝复合材料性能的影响。红外光谱和电镜的分析表明:加入PE-g-MAH可以促进木质纤维(纸)与塑料基体相容。随着PE-g-MAH添加量的增加,复合材料的拉伸强度、弯曲强度和吸水率先增加后减小。当PE-g-MAH用量为5份时,复合材料的冲击强度为11.87 MPa,比添加前提高了154.7%。     

分子印迹微溶胶的制备及对水中2,4-二氯苯酚的吸附研究

以2,4-二氯苯酚(2,4-DCP)为模板分子,甲基丙烯酰胺为功能单体,三羟甲基丙烷三甲基丙烯酸酯为交联剂,合成了一系列分子印迹聚合物微溶胶(MIPM)。采用紫外光谱法(UV)研究模板与单体间的结合作用,扫描电子显微镜(SEM)表征印迹聚合物的表面形貌。通过平衡吸附试验对MIPM的吸附性能进行评价。结果表明,当以乙腈作为致孔剂,功能单体与模板分子的摩尔比为4:1时,MIPM对2,4-DCP的印迹因子为1.93,最大吸附容量为159.61 mg/g,吸附在150 min左右可达到平衡。将MIPM用作固相萃取(SPE)柱填料,对水样中的2,4-DCP进行富集试验,回收率为96.30%~108.66%。