全钒液流电池用新型全氟磺酸离子交换膜制备及性能研究

通过溶液流延成膜法制备了具有不同离子交换容量(IEC)的全氟磺酸(PFSA)离子交换膜,并测试了其吸水率、电导率、钒离子(Ⅴ(Ⅳ))透过率和选择性系数。研究发现,具有高IEC值的PFSA离子交换膜具有相对较低的Ⅴ(Ⅳ)离子透过率和较高的质子电导率。其中IEC值为1.10mmol/g的PFSA离子交换膜对Ⅴ(Ⅳ)离子具有最高的选择性,其选择性系数为Nafion 117膜的2.97倍。     

全氟离子交换膜的再生及应用

叙述了再生全氟离子交换膜的性能、特点、再生成本及应用。     

全氟离子交换膜特性参数的测试方法

离子交换膜是氯碱电解生产的技术核心,膜机体要有足够的机械强度,形态尺寸稳定;良好的化学热稳定性;优越的电化学性能及较低的膜电阻.研究全氟离子交换膜的性能、特性参数及测试方法,对于合理优化膜的性能指标即物理机械性能、化学性能及电化学性能等具有指导价值.     

TiO2/全氟磺酸树脂纳米杂化薄膜的制备

采用溶胶-凝胶法制备了TiO2/全氟磺酸树脂(Perfluorosulfonated Resin,简称PSR)纳米杂化薄膜,并通过透射电镜(TEM)、X射线衍射(XRD)、红外光谱(FT-IR)、紫外可见光谱(UV-vis)及热重分析(TGA)等技术较为全面地测试了杂化薄膜的形貌、晶型、结构、光学及热力学性能.结果表明,TiO2/PSR纳米杂化薄膜表面平整光滑,基本没有裂纹;杂化薄膜在经水热处理后,两相在纳米尺度均匀分散,TiO2粒径约为8～10nm,呈锐钛矿型;同时杂化薄膜具有良好的光学透明性和紫外吸收性能,且随着TiO2含量的增加,全氟磺酸树脂紫外吸收性能有显著提高.     

热处理对全氟离子交换膜性能的影响

全氟离子交换膜(PFIEM)是质子交换燃料电池和离子膜氯碱工业的关键材料,在燃料电池、氯碱行业、钒电池等方面应用广泛,是目前无可替代的关键部件之一。它的结构与性能直接关系着电池或电解槽的性能好坏。热处理作为一种传统工艺过程,简便易行,广泛用于全氟离子交换膜性能的研究。从离子膜的不同性能出发,分别阐述了热处理对质子电导率、甲醇透过率、力学性能、选择渗透性等性能的影响,并总结了目前这方面研究的特点与发展方向。     

聚过氟磺酸离子交换膜电性能研究

研究了聚过氟磺酸离子交换膜在不同环境条件下的导电性能，从实用的角度出发，考察了膜在不同种类，不同浓度的电解质溶液中的导电能力，分析了各种离子对其导电性能的影响。根据实验数据，对膜的导电机理进行了推测，测定了膜对几种常用离子的选择性系数，研究了温度对膜导电能力的影响。     

全氟羧酸离子交换膜内金属硫化物超微粒的制备及其性能

首次以全氟羧酸离子交换膜为生成介质制备出纳米尺寸Ｚｎｓ。ＣｄＳ及Ｐｂｓ超微粒。ＺｎＳ为非晶态，而ＣｄＳ，ＰｂＳ超微粒分别为六方和立方晶型；通过改变膜的含水量得到不同尺寸的ＰｂＳ超微粒，并且随颗粒尺寸减小，其三阶光学非线性极化率ｘ＾（３）增大。     

含磷酸结构全氟磺酸质子交换膜研究进展

质子交换膜燃料电池(PEMFCs)具有独特的能源转化和储存方式,因此引起了科学家广泛的研究兴趣.全氟磺酸质子交换膜(PFSA)是目前低温型PEMFCs(<100℃)中应用最为广泛的关键核心材料之一,在很大程度上决定着PEMFCs的性能优劣.提高工作温度可以赋予PEMFCs更高的转化效率、更快电极反应、更高的杂质耐受能力、更便捷的水热管理方式等,然而,质子交换膜(PEM)在高温下的传质性能衰减阻碍PEMFCs的高温应用.引入磷酸结构是目前改善PEM高温传质性能常用的策略.本文总结了近年来含磷酸结构全氟磺酸质子交换膜的研究进展,并讨论了引入磷酸结构后存在的问题,为后续的高温质子交换膜的研究工作提供指导作用.     

全氟磺酸树脂中不稳定端基的热行为研究

用傅立叶变换红外光谱和热失重方法对全氟磺酸树脂中的不稳定端基的热行为进行了研究。     

Hot melt extrusion versus spray drying: hot melt extrusion degrades albendazole

Abstract

The purpose of this study was to enhance the dissolution properties of albendazole (ABZ) by the use of amorphous solid dispersions. Phase diagrams of ABZ–polymer binary mixtures generated from Flory–Huggins theory were used to assess miscibility and processability. Forced degradation studies showed that ABZ degraded upon exposure to hydrogen peroxide and 1 N NaOH at 80?°C for 5?min, and the degradants were albendazole sulfoxide (ABZSX), and ABZ impurity A, respectively. ABZ was chemically stable following exposure to 1 N HCl at 80?°C for one hour. Thermal degradation profiles show that ABZ, with and without Kollidon^® VA 64, degraded at 180?°C and 140?°C, respectively, which indicated that ABZ could likely be processed by thermal processing. Following hot melt extrusion, ABZ degraded up to 97.4%, while the amorphous ABZ solid dispersion was successfully prepared by spray drying. Spray-dried ABZ formulations using various types of acids (methanesulfonic acid, sulfuric acid and hydrochloric acid) and polymers (Kollidon^® VA 64, Soluplus^® and Eudragit^® E PO) were studied. The spray-dried ABZ with methanesulfonic acid and Kollidon^® VA 64 substantially improved non-sink dissolution in acidic media as compared to bulk ABZ (8-fold), physical mixture of ABZ:Kollidon^® VA 64 (5.6-fold) and ABZ mesylate salt (1.6-fold). No degradation was observed in the spray-dried product for up to six months and less than 5% after one-year storage. In conclusion, amorphous ABZ solid dispersions in combination with an acid and polymer can be prepared by spray drying to enhance dissolution and shelf-stability, whereas those made by melt extrusion are degraded.     

Preparation and evaluation of metoprolol tartrate sustained-release pellets using hot melt extrusion combined with hot melt coating

The objective of this study was to prepare and evaluate metoprolol tartrate sustained-release pellets. Cores were prepared by hot melt extrusion and coated pellets were prepared by hot melt coating. Cores were found to exist in a single-phase state and drug in amorphous form. Plasticizers had a significant effect on torque and drug content, while release modifiers and coating level significantly affected the drug-release behavior. The mechanisms of drug release from cores and coated pellets were Fickian diffusion and diffusion–erosion. The coated pellets exhibited sustained-release properties in vitro and in vivo.     

Effect of extrusion process melt temperature on polyurethane catheter surfaces

Determination of optimum process melt temperature of medical-grade polyurethane (PU) is an indispensable challenge witnessed during the catheter manufacturing process. This resin does not contain a uniform crystal structure but exists in an amorphous state. The lower shore hardness PU material, used in catheter manufacture, has just a “melt temperature range” instead of a definite melt temperature. This temperature plays a significant role in shaping the catheter surfaces, which directly interact with human tissues and cause health-care-associated issues. The objective of this work is to evaluate the effects of variations in the melt temperature during the extrusion process of medical catheters on their outer surfaces. Medical PU, Pellethane, was used for this study and 12 Fr (4.0?mm) catheters were manufactured with optimal validated parameters, excluding melt temperature. The manufactured catheters were examined under Optical Microscopy and Atomic Force Microscopy (AFM) for surface topography studies. Wettability studies were carried out using a Goniometer for evaluating the water contact angles. The effects of melt temperature on the surface roughness (R_a) and wettability of the catheter surfaces were analyzed through analysis of variance (ANOVA). The conclusion was that the process melt temperature variations have a significant effect on catheter R_a and its wettability characteristics.     

Utility of the hyperbranched polymer Hybrane S1200 for production of instant-release particles by hot melt extrusion

Particles composed of 90:10 or 80:20 mixtures of the hyperbranched poly(esteramide) Hybrane S1200 and the poorly water-soluble drug hydrochlorothiazide were produced by hot melt extrusion at maximum temperatures of 90°C without any need for addition of a plasticizer. In dissolution rate assays in USP 29 apparatus II, particles of the smallest size category (<250 µm) containing 10% of hydrochlorothiazide released 95% of their load within 5?min. This fast release is attributed to the combination of the high solubility of Hybrane S1200, the dispersion of the drug in non-crystalline form in the polymer matrix (attested to by the results of powder X-ray diffractometry, and scanning electron microscopy), and to the fact that the main interaction between drug and polymer is through hydrogen bonds (attested to by ATR-IR difference spectra).     

温度对熔体挤出自增强HDPE棒材显微组织和力学性能的影响

利用自制模具,在不同的温度下成功的制备了直径为7.2mm的自增强高密度聚乙烯(HDPE)棒材.通过SEM观察、DSC分析、WAXD分析与力学性能测试,研究挤出温度对熔体挤出自增强HDPE棒材微观结构和力学性能的影响.研究结果表明,挤出温度是影响熔体挤出自增强HDPE棒材结构和力学性能的重要参数.随着挤出温度的降低,自增强棒材的微晶尺寸和结晶度大幅提高,晶面间距几乎未变化,熔点向高温区发生漂移,试样内部有大量的微纤结构存在.在130℃下挤出棒材的拉伸强度和抗弯强度分别为220.6MPa和152.9MPa,都将近是未增强试样的10倍.     

Drug dispersion degree and drug dissolution rate in Hybrane S1200-based instant-release matricial particles prepared by hot melt extrusion

The objective of this study is to evaluate the dissolution of a poorly soluble drug (prednisolone) from different sized matricial particles (from <250 to >1500?µm) with two drug contents (10% or 20%) obtained by hot melt extrusion using the hyperbranched polyesteramide Hybrane S1200 (water-soluble and with a Tg of 45?°C) as the carrier. X-ray diffraction, differential scanning calorimetry and SEM studies permit us to conclude that in 10% prednisolone extrudate, the drug is mainly dispersed within the carrier, whereas in those containing 20% an important fraction of the drug remains in a crystalline state and is accumulated on the surface of the extrudates. On particles proceeding from 10% drug extrudate, the drug dissolution rate is very high and slightly dependant on particle size and in all cases, higher than the pure micronized drug. However, on particles proceeding from 20% prednisolone extrudate particle size have a major effect on drug dissolution rate, attributable to higher proportions of crystalline drug accumulated on the surface, hindering polymer dissolution. Thus, the reduction of the particle size after extrudate grinding creates new surfaces from inside, that leads to strong increments on prednisolone dissolution rate, and becomes higher than the pure micronized drug one when the particle size is <250?µm.     

Influence of plasticizers and drugs on the physical-mechanical properties of hydroxypropylcellulose films prepared by hot melt extrusion

Hydroxypropylcellulose (HPC) films containing drugs or hydrophilic or hydrophobic plasticizers were prepared by a hot melt extrusion process. Polyethylene glycol 8000 (PEG 8000) 2%, triethyl citrate (TEC) 2%, acetyltributyl citrate (ATBC) 2%, and polyethylene glycol 400 (PEG 400) 1% were the plasticizing agents studied. In addition, either hydrocortisone (HC) 1% or chlorpheniramine maleate (CPM) 1% was incorporated into the films as a model drug. The physical-mechanical properties of the films that were investigated included tensile strength (TS), percentage elongation (%E), and Young's modulus (YM). Differential scanning calorimetry (DSC) was utilized to determine glass transition temperatures (T_g' s). These parameters were studied as a function of time and temperature. The glass transition temperatures initially decreased with the inclusion of the drugs and plasticizers. However, after 6 months aging, films containing PEG 400 and HC showed a marked increase in T_g. The films containing PEG 400 showed physical-mechanical instability in all parameters studied. All extruded films exhibited a marked decrease in TS in contrast to a large increase in %E when testing was performed perpendicular to flow versus in the direction of flow. In addition, a consistent film of HPC in the absence of drugs or plasticizers could not be extruded due to the excessive stress on the equipment. Although the theoretical percentage of CPM on aging remained fairly constant over the processing temperature ranges in this study, the HC levels remaining in the extruded films during storage were a function of time and temperature.     

Development of a HPMC-based controlled release formulation with hot melt extrusion (HME)

The objective of this study was to develop hydroxypropyl methylcellulose (HPMC) based controlled release (CR) formulations via hot melt extrusion (HME) with a highly soluble crystalline active pharmaceutical ingredient (API) embedded In the polymer phase. HPMC is considered a challenging CR polymer for extrusion due to its high glass transition temperature (T_g), low degradation temperature, and high viscosity. These problems were partially overcome by plasticizing the HPMC with up to 40% propylene glycol (PG). Theophylline was selected as the model API. By using differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and X-ray powder diffraction (XRPD), the physical properties of the formulations were systematically characterized. Five grades of HPMC (Methocel^®) – E6, K100LV, K4M, K15M, and K100M – were tested. The extrusion trials were conducted on a 16?mm twIn screw extruder with HPMC/PG placebo and formulations containing theophylline/HPMC/PG (30:42:28, w/w/w). The dissolution results showed sustained release profiles without burst release for the HPMC K4M, K15M, and K100M formulations. The extrudates have good dissolution stability after being stressed for 2 weeks under 40°C/75% RH open dish conditions and the crystalline API form did not change upon storage. Overall, the processing windows were established for the HPMC based HME-CR formulations.     

Optimization of hot melt extrusion parameters for sphericity and hardness of polymeric face-cut pellets

The aim of this study was to formulate face-cut, melt-extruded pellets, and to optimize hot melt process parameters to obtain maximized sphericity and hardness by utilizing Soluplus^® as a polymeric carrier and carbamazepine (CBZ) as a model drug. Thermal gravimetric analysis (TGA) was used to detect thermal stability of CBZ. The Box–Behnken design for response surface methodology was developed using three factors, processing temperature (?°C), feeding rate (%), and screw speed (rpm), which resulted in 17 experimental runs. The influence of these factors on pellet sphericity and mechanical characteristics was assessed and evaluated for each experimental run. Pellets with optimal sphericity and mechanical properties were chosen for further characterization. This included differential scanning calorimetry, drug release, hardness friability index (HFI), flowability, bulk density, tapped density, Carr’s index, and fourier transform infrared radiation (FTIR) spectroscopy. TGA data showed no drug degradation upon heating to 190?°C. Hot melt extrusion processing conditions were found to have a significant effect on the pellet shape and hardness profile. Pellets with maximum sphericity and hardness exhibited no crystalline peak after extrusion. The rate of drug release was affected mainly by pellet size, where smaller pellets released the drug faster. All optimized formulations were found to be of superior hardness and not friable. The flow properties of optimized pellets were excellent with high bulk and tapped density.     

IN690合金管热挤压温升与挤压力的研究

温升和挤压力是影响钢管挤压过程的重要指标,利用热模拟实验获得了IN690合金的热加工本构关系,建立了IN690合金钢管热挤压过程的有限元模型.采用正交实验设计的仿真实验系统分析了坯料温度（T b=1000～1200℃）、挤压速度（v=20～200 mm/s）和模具预热温度（T d=300～500℃）对管材成形过程中温升...