共聚物水凝胶角膜接触镜材料的初期脱水行为

以N-乙烯基吡咯烷酮、甲基丙烯酸羟乙酯以及甲基丙烯酸甲酯、甲基丙烯酸乙酯或者甲基丙烯酸丁酯为原料,制备共聚物水凝胶角膜接触镜材料,建立了膜状水凝胶材料的脱水模型,采用重量法和热失重法研究了该材料的初期脱水行为.结果表明,水凝胶膜的初期脱水速度与其交联密度的平方成反比;共聚物水凝胶中N-乙烯基吡咯烷酮的含量越大,脱水速率越大;甲基丙烯酸甲酯、甲基丙烯酸乙酯以及甲基丙烯酸丁酯的含量越大,脱水速率越低,以甲基丙烯酸乙酯最明显;在初期脱水阶段,水凝胶膜的脱水行为可用一级动力学描述.     

Triazine‐containing benzoxazine and its high‐performance polymer

A new synthetic route was designed to significantly increase the content of triazine structure in benzoxazine resin. 2,4,6‐Tri(4‐hydroxylphenyl)‐13,5‐s‐triazine (TP) was synthesized by cyclotrimerization of 4‐cyanolphenol and then benzoxazine monomer‐containing triazine [2,4,6‐tri(3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazin‐6‐yl)‐1,3,5‐s‐triazine (BZ‐ta)] was synthesized via Mannich reaction from TP. Finally, the cross‐linked polymer P(BZ‐ta) was produced by thermal polymerization of BZ‐ta. BZ‐ta was characterized by nuclear magnetic resonance spectroscopy (NMR), fourier transform infrared spectroscopy (FTIR), mass spectrum, elemental analysis, and viscosity measurement. Curing behavior of BZ‐ta was studied by differential scanning calorimetry, FTIR, and gel permeation chromatography. The structure and properties of P(BZ‐ta) were investigated by powder X‐ray diffraction, dynamic mechanical analysis, and thermogravimetric analysis. The results showed that the P(BZ‐ta) had high glass temperature (T_g = 322°C), excellent thermal oxidation stability (5 and 10% weight loss temperatures in air up to 403 and 453°C, respectively), high char yield (64%, 800°C in nitrogen), and high flame‐retardance (limiting oxygen index, 39.7). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Alignment of a nematic liquid crystal on nano‐grooved material

We demonstrate the alignment characteristics of a nematic liquid crystal on the surface of a nanoimprinted material that is a functionally graduated composite suitable for the alignment of a liquid crystal on a groove surface processed by nanoimprinting lithography. With the electro‐optic characteristics shown in twisted nematic and in‐plane switching modes, the potential liquid crystal applications are examined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高亲水性有色隐形眼镜的紫外合成与表征

以当前研究较多的甲基丙烯酸β羟乙酯(HEMA)、N乙烯基α吡咯烷酮(NVP)为单体(质量比1∶1),安息香乙醚(BEE)为引发剂(1%,质量分数),透明蓝为色料,利用紫外光引发自由基反应,合成了有色隐形眼镜。红外光谱定性说明单体参与了聚合反应,色料质量分数为2.46×10-5时,镜片浸出液pH与人体泪液接近,平均透光率达到97%以上,含水率为66.51%,抗张强度为916.26 Pa(湿态)。扫描电镜下观察到均匀交织的网状结构,进一步证明了镜片的高含水率、高透氧率、高抗张强度。     

Effect of the stress relaxation property of acrylic pressure‐sensitive adhesive on light‐leakage phenomenon of polarizer in liquid crystal display

The acrylic pressure‐sensitive adhesive systems with the different stress relaxation abilities are prepared by varying the curing agent from 0.3% to 3.0% and the effect of the stress relaxation ability of pressure‐sensitive adhesive system on the durability of LCD polarizer was investigated. The stress relaxation ability of the crosslinked pressure‐sensitive adhesive systems was measured by transient tensile test and dynamic viscoelastic test. And the durability was evaluated by the light‐leakage test of polarizer coated with the pressure‐sensitive adhesive after it was aged under the condition of 60°C and the relative humidity of 95% for 72 h. It was observed that the stress relaxation ability of pressure‐sensitive system is decreased with the crosslinking density, as intended. And the pressure‐sensitive adhesive with the lower stress relaxation ability exhibited the lower light‐leakage and consequently the higher durability than the other PSA systems. This observation is obviously contradictory to the previous design strategy of PSA system and the reason for this observation was discussed briefly. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Properties of a few aromatic poly(thioether ketones) as sulfur‐containing high‐performance polymers

Several basic physical properties of poly(thioether ketones) (PTEKs) were studied in comparison with corresponding ether analogs, poly(ether ketones) (PEKs), and various typical engineering plastics. The water absorption of PTEK (0.13%) was lower than that of the corresponding PEK (0.16%), probably because of the hydrophobic nature of the sulfide group. The dielectric breakdown strengths of PTEK and PEK were much greater than that of commercially available polymers. PTEK had higher dielectric breakdown strength than PEK. Although the volume resistivity of PEK considerably decreased after water absorption, that of PTEK remained high even after water absorption. PTEK exhibited a remarkably high refractive index (n_D²³ 1.66). α‐Transition corresponding to T_g was observed at a high temperature (PTEK‐1, 235°C; PTEK‐2, 269°C) in the dynamic mechanical analysis. Young's modulus and tensile strength of PTEK were comparable to those of commercial high‐performance polymers. PTEK also exhibited excellent flame resistance. Although the linear thermal expansion coefficient of PTEK was greater than that of PEEK, it was still within a practically acceptable level. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1869–1874, 2004     

Modeling of heat recovery from a steam‐gas mixture in a high‐temperature sorption process

A high pressure condenser is considered to remove water vapor as well as recover heat from the desorbed steam—CO₂ gas mixture in a novel sorption enhanced reaction process. It is possible to have water condensation at the gas side as well as water evaporation at the coolant water side because of large temperature difference between the hot and cold side. A model of heat and mass transfer and phase change was developed to understand the complex phenomena associated with the simultaneous condensation and evaporation taking place in the unit. A finite difference method was used to solve the boundary value problem. Additional insight was obtained by describing the operating lines and equilibrium condition in an enthalpy diagram. The model was used to explore the performance in terms of the heat recovery. The heat recovery was best at the beginning of the process when the superheated steam was generated. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Nanospace‐confined synthesis of coconut‐like SnS/C nanospheres for high‐rate and stable lithium‐ion batteries

Coconut‐like monocrystalline SnS/C nanospheres are developed as anode materials for lithium‐ion batteries by a micro‐evaporation‐plating strategy in confined nanospaces, achieving reversible capacities as high as 936 mAh g^?1 at 0.1 A g^?1 after 50 cycles and 830 mAh g^?1 at 0.5 A g^?1 for another 250 cycles. The remarkably improved electrochemical performances can be mainly attributed to their unique structural features, which can perfectly combine the advantages of the face‐to‐face contact of core/shell nanostructure and enough internal void space of yolk/shell nanostructure, and therefore well‐addressing the pivotal issues related to SnS low conductivity, sluggish reaction kinetics, and serious structure pulverization during the lithiation/delithiation process. The evolutionary process of the nanospheres is clearly elucidated based on experimental results and a multiscale kinetic simulation combining the microscopic reaction‐diffusion equation and the mesoscopic theory of crystal growth. Furthermore, a LiMn₂O₄//SnS/C full cell is assembled, likewise exhibiting excellent electrochemical performance. © 2018 American Institute of Chemical Engineers AIChE J, 64: 1965–1974, 2018     

Treatment of high‐level arsenic‐containing wastewater by fluidized bed crystallization process

Gallium arsenide technology has been widely applied in the communication and optical electronics industries. The process of chip manufacturing produces a stream of wastewater unique in its low flow rate and high arsenic concentration. Fluidized bed crystallization (FBC) technology combines the advantages of a fluidized bed reactor and crystallization. It is highly efficient with low capital and operational costs, while producing no sludge. The waste from the FBC is small in volume, high in crystal purity and recyclable. Jar tests were first performed to evaluate the precipitation of arsenic sulfide. Then a lab‐scale fluidized bed reactor was applied to screen critical operational parameters and the process was optimized to meet the wastewater discharge standard. The results obtained in this study confirmed that the FBC process is capable of treating wastewater containing high concentrations of arsenic, reducing the concentration to µg L^?1 levels. Sulfide dosage and operating pH are the two most significant parameters determining the residual arsenic concentration of the effluent, with optimum conditions of pH = 2 and S/As = 2.2 to meet the local discharge limit. Copyright © 2007 Society of Chemical Industry     

Mixing performance comparison of milliscale continuous high‐shear mixers

Mixing performance of two continuous flow millilitre‐scale reactors (volumes 9.5 mL and 2.5 mL) equipped with rotor‐stator mixers was studied. Cumulative residence time distributions (RTD) were determined experimentally using a step response method. Distributions were measured for both reactors by varying impeller speed and feed flow rate. The mixing effect was determined by measured RTDs. Computational fluid dynamics (CFD) were used to verify that the residence time distribution in the measurement outlet agreed with the outlet flow. The mixing power of both reactors was determined using a calorimetric method. The reactor inlet flow rate was found to affect mixing performance at 1–13 s residence times but the effect of impeller speed could not be noted. Both milliscale reactors are close to an ideal continuous stirred‐tank reactor (CSTR) at the studied impeller speed and flow rate ranges. The specific interfacial area was found to depend on the reactor inlet flow rate at constant impeller speed for the case of copper solvent extraction.

     

Oxo‐biodegradability of high‐density polyethylene films containing limited amount of isotactic polypropylene

Limited amount of isotactic polypropylene (iPP) is added to high‐density polyethylene (HDPE) containing 1% w/w an oxo‐biodegradable additive and extruded and converted to films. The films are put under UV irradiation for different periods of time. Irradiation of the films for 6 weeks imposes remarkable effects on viscosity average molecular weight (M_v) and carbonyl index (CI) of them. M_v decreases from 3.4 × 10⁵ to 4.7 × 10⁴ g mol^?1 for neat HDPE films; from 3.1 × 10⁵ to 3.3 × 10⁴ g mol^?1 for the films containing oxo compound, and from 1.5 × 10⁵ to 2.6 × 10⁴ g mol^?1 for the films containing oxo compound and 1% w/w iPP. Carbonyl index of the neat HDPE films increases from 4 to 8.7 while for the sample containing only the oxo compound it increases from 4.5 to 7.3 and for the sample containing both oxo compound and iPP it decreases from 12.0 to 8.8. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) indicate more cracks and uniform degradation in the samples containing iPP and oxo compound. Thermogravimetric analysis (TGA/DTG) of the samples shows that the samples containing iPP and oxo compound have lower decomposition temperature after UV irradiation. Finally, it can be said that the presence of iPP in HDPE matrix containing oxo compound can improve HDPE oxo‐biodegradablity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45843.     

Thermal aging of a blend of high‐performance fibers

The focus of this work is the study of the thermal aging of high‐performance fibers used in the making of fire protective garments. Accelerated thermal aging tests were carried out on fabric samples made up of a blend of Kevlar® (poly p‐phenylene terephthalamide) and PBI (poly benzimidazole) staple fibers, as well as on yarns pulled from this fabric, by means of exposure to elevated temperatures, comprised between 190°C and 320°C. All samples underwent loss of breaking force retention. The material thermal life, defined as the time required for the fibers to attain a 50% reduction of the original breaking force, ranged between a dozen of days at the lowest exposure temperature, to less than an hour at the highest. Breaking force data were fitted using the Arrhenius model following two different approaches, namely the extrapolated thermal life value and the shift factors yielded by the time‐temperature superposition (TTS). The Arrhenius model seemed to describe appropriately the overall aging process, as inferred from the excellent fit obtained when using both approaches, although activation energies provided from both approaches are different. To follow the chemical evolution of the material with thermal aging, Fourier‐transform infrared (FTIR) analyses were conducted. The qualitative analysis of the FTIR spectra showed little evidence of chemical changes between the aged and the nonaged samples, indicating either that the aging process carries on without significant modification of the chemical structure of the fibers, or that FTIR is not an appropriate method to spot such a modification. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Poly(ethylene glycol)‐based poly(urethane isocyanurate) hydrogels for contact lens applications

Over the past few decades, the global use and market of contact lenses have expanded steadily. Due to the many demands on material properties (e.g. mechanical, optical and biological), the development of novel contact lens materials is challenging. Specifically, the ideal combination of high equilibrium water content, high toughness in the hydrated state and low protein adsorption is difficult to realize. In this work, poly(ethylene glycol)‐based poly(urethane isocyanurate) (PEG PUI) type hydrogels that combine the above important properties are presented as a new class of materials for contact lens applications. It is shown that these PEG PUI hydrogels demonstrate high toughness values in the hydrated state ranging from 98 to 226 kJ m^?3 and elastic moduli ranging from 0.8 to 17.2 MPa for networks with equilibrium water contents ranging from 76.3 to 16.1 wt%. These hydrogels also demonstrate transmittance values >90% across the visible spectrum, clarities close to 100% in most cases and refractive indices ranging from 1.48 to 1.36. Importantly, these hydrogels are non‐cytotoxic and demonstrate lower bovine serum albumin adsorption values than several commercial contact lenses of 0.24 to 0.65 mg g^?1 compared to 0.55 to 1.38 mg g^?1 after 24 h, respectively. This combination of high equilibrium water content, high toughness in the hydrated state and low protein adsorption is exceptional. These properties can be attributed to the PEG PUI network structure: the use of a PEG polymeric backbone provides hydrophilicity and chemical inertness while the PUI‐type crosslinking units provide high toughness in the hydrated state. © 2019 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Preparation and properties of high‐performance polysilsesquioxanes/bismaleimide‐triazine hybrids

A novel kind of high‐performance hybrids (coded as POSS‐NH₂/BT) with significantly decreased curing temperature, lowered dielectric constant and loss, and improved thermal resistance were developed, which were prepared by copolymerizing bismaleimide with cage octa(aminopropylsilsesquioxane) (POSS‐NH₂) to produce POSS‐containing maleimide, and then co‐reacted with 2,2′‐bis(4‐cyanatophenyl) isopropylidene. The curing behavior and typical properties of cured POSS‐NH₂/BT were systematically investigated. Results show that POSS‐NH₂/BT hybrids have lower curing temperatures than BT resin because of the additional reactions between  OCN and amine groups. Compared with BT resin, all hybrids show improved dielectric properties. Specifically, hybrids have slightly decreased dielectric constants and similar dependence of dielectric constant on frequency over the whole frequency from 10 to 10⁶ Hz; more interestingly, the dielectric loss of hybrids is only 25% of that of BT resin at the frequency lower than 10⁵ Hz, whereas all hybrids and BT resin have almost equal dielectric loss when the frequency is higher than 10⁵ Hz. In addition, POSS‐NH₂/BT hybrids also show good thermal and thermo‐oxidative stability compared with BT resin. All these differences in macroproperties are attributed to the difference in chemical structure between POSS‐NH₂/BT hybrids and BT resin. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of high‐energy electron beam on low‐density polyethylene materials containing EVA

A series of low‐density polyethylene (LDPE) blends with different amounts of ethylene–vinyl–acetate (EVA) was prepared and irradiated with 10 MeV electron beam in the range of 0–250 kGy at room temperature in air. EVA was used as a compatibilizer and softener in four different amounts: 5, 10, 20, and 30 wt %, based on polyethylene (PE). The crosslinking of the samples was studied on the basis of gel‐content measurements as well as some thermal and mechanical properties of the specimens. The results indicated that the LDPE and LDPE–EVA blends could be crosslinked by a high‐energy electron beam, of which their thermal and mechanical properties changed effectively, however, because of EVA content of the polymer; the blends were more sensitive to lower doses of radiation. These studies were carried out to obtain a suitable compound for heat‐shrinkable tubes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1049–1052, 2004     

Modification of high‐performance polymer composite through high‐energy radiation and low‐pressure plasma for aerospace and space applications

In this investigation, attempts are made to modify a high‐performance polymer such as polybenzimidazole (PBI) (service temperature ranges from ?260°C to +400°C) through high‐energy radiation and low‐pressure plasma to prepare composite with the same polymer. The PBI composites are prepared using an ultrahigh temperature resistant epoxy adhesive to join the two polymer sheets. The service temperature of this adhesive ranges from ?260°C to +370°C, and in addition, this adhesive has excellent resistance to most acids, alkalis, solvents, corrosive agents, radiation, and fire, making it extremely useful for aerospace and space applications. Prior to preparing the composite, the surface of the PBI is ultrasonically cleaned by acetone followed by its modification through high‐energy radiation for 6 h in the pool of a SLOWPOKE‐2 (safe low power critical experiment) nuclear reactor, which produces a mixed field of thermal and epithermal neutrons, energetic electrons, and protons, and γ‐rays, with a dose rate of 37 kGy/h and low‐pressure plasma through 13.56 MHz RF glow discharge for 120 s at 100 W of power using nitrogen as process gas, to essentially increase the surface energy of the polymer, leading to substantial improvement of its adhesion characteristics. Prior to joining, the polymer surfaces are characterized by estimating surface energy and electron spectroscopy for chemical analysis (ESCA). To determine the joint strength, tensile lap shear tests are performed according to ASTM D 5868–95 standard. Another set of experiments is carried out by exposing the low‐pressure plasma‐modified polymer joint under the SLOWPOKE‐2 nuclear for 6 h. Considerable increase in the joint strength is observed, when the polymer surface is modified by either high‐energy radiation or low‐pressure plasma. There is further significant increase in joint strength, when the polymer surface is first modified by low‐pressure plasma followed by exposing the joint under high‐energy radiation. To simulate with spatial conditions, the joints are exposed to cryogenic (?196°C) and high temperatures (+300°C) for 100 h. Then, tensile lap shear tests are carried out to determine the effects of these environments on the joint strength. It is observed that when these polymeric joints are exposed to these climatic conditions, the joints could retain their strength of about 95% of that of joints tested under ambient conditions. Finally, to understand the behavior of ultrahigh temperature resistant epoxy adhesive bonding of PBI, the fractured surfaces of the joints are examined by scanning electron microscope. It is observed that there is considerable interfacial failure in the case of unmodified polymer‐to‐polymer joint whereas surface‐modified polymer essentially fails cohesively within the adhesive. Therefore, this high‐performance polymer composite could be highly useful for structural applications in space and aerospace. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1959–1967, 2006     

Preparation of nanopolyethylene wire with carbon nanotubes‐supported Cp2ZrCl2 catalyst

Nanowires were prepared by ethylene polymerization in situ with carbon nanotubes (CNTs)‐supported Cp₂ZrCl₂ catalyst. It was found that the metallocene catalyst was first adsorbed on the surface of the CNTs and then the polymerization of ethylene was initiated. The resulting PE could encapsulate on the surface of the CNTs to form nanowire. The diameter of nanowire could be controlled easily by the polymerization conditions. The possible mechanism of formation of nanopolyethylene wire is proposed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1291–1294, 2006     

Properties and origins of high‐performance poly(phenylene oxide)/cyanate ester resins for high‐frequency copper‐clad laminates

A high‐performance matrix is the key base for the fabrication of high‐frequency copper‐clad laminates. A high‐performance resin system based on commercial poly(phenylene oxide) (PPO) and 2,2′‐bis(4‐cyanatophenyl) isopropylidene (BADCy), coded as PPO‐n/BADCy (where n is the weight parts of PPO per 100 weight parts of BADCy), was developed. The effect of PPO on the key properties, including the dielectric and thermal properties, water resistance, and toughness, of the cured resins was investigated extensively. The results show that PPO not only catalyzed the curing reaction of BADCy but also reacted with BADCy to form a single‐phase structure. Furthermore, compared with the cured BADCy resin with 1 phr epoxy resin as a catalyst, the cured PPO‐n/BADCy resins had significantly increased impact strengths and decreased dielectric constants, loss, and water resistance. The reasons behind these desirable improvements are discussed from the view of structure–property relationships. These results suggest that the PPO‐n/BADCy system has great potential to be used as a matrix for high‐frequency copper‐clad laminates or other advanced composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Development of lightweight high‐performance polymeric composites with functionalized nanotubes

In this article, we highlight the various properties of an ultralightweight poly(ether ketone) (PEK) composite. In this study, special emphases were laid on the preparation of low‐density, high‐performance polymeric foams with foaming agents and activators. PEK, foamed PEK, and carbon nanotube (CNT)–reinforced foamed PEK composites were considered for this study. The density of the polymer decreased with the reinforcement of the foaming agent. We also noted that with the reinforcement of the modified CNT in the foamed PEK, there were marginal increases in the density and hardness of the composites. We also noted that the mechanical properties of the CNT‐reinforced foamed PEK was on par with those of basic PEK. Thermogravimetric analysis gave us a clear indication that the thermal stability of the composites was not affected by the reinforcing foaming agent and nanoparticles. Scanning electron microscopy and transmission electron microscopy clearly indicated the formation of foams and also the dispersion of nanoparticles in the composite structure. We also observed that because of the reinforcement of multiwalled CNTs in the composite, there was an improvement in the hardness of the composite. An increase in the specific strength was observed in the foamed PEK composites. The CNT‐reinforced foamed PEK showed a marginal decrease in the specific strength without a compromise in the impact strength. The impact strength of the CNT‐reinforced foamed PEK composite was found to be similar to that of the basic PEK. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43471.