热致相分离法制备聚偏氟乙烯微孔膜的微观结构研究

以邻苯二甲酸二丁酯(DBP)和十二醇组成的混合溶剂为稀释剂,采用热致相分离法(TIPS法)制备了聚偏氟乙烯(PVDF)微孔膜.测试了不同体系的固-液相分离温度,研究了稀释剂、冷却条件、聚合物浓度对膜断面微观结构的影响.     

热致相分离法制备聚偏氟乙烯微孔膜的结构及性能研究

以聚偏氟乙烯(PVDF)和邻苯二甲酸二丁酯(DBP)作为膜材料和稀释剂,采用热致相分离法(TIPS法)制备了聚偏氟乙烯(PVDF)微孔膜.通过差示扫描量热仪(DSC)测试了不同混合体系的固-液相分离温度,利用扫描电镜(SEM)观察和研究了稀释剂、冷却条件、聚合物浓度对膜断面微观结构的影响.     

稀释剂种类对聚偏二氟乙烯多孔膜性能的影响

以聚偏二氟乙烯(PVDF)为原料,邻苯二甲酸二丁酯(DBP)和二苯甲酮(DPK)为稀释剂,通过不同的相分离机理(固-液相分离或液-液相分离)制备了不同结构和性能的多孔膜.建立了聚合物/稀释剂体系的二元相图,同时采用扫描电子显微镜(SEM)、孔隙率和水通量测试、差示扫描量热仪(DSC)和X射线衍射仪(XRD)对多孔膜的结构和性能进行表征.研究结果表明:由PVDF/稀释剂体系制备的多孔膜断面结构主要为表面带有微孔的球粒.PVDF/DPK体系在PVDF含量为20 wt％、0℃水浴冷却的条件下获得了双连续结构的多孔膜,其孔隙率和水通量优于同体系其它多孔膜.PVDF多孔膜的结晶度随稀释剂含量的增大而增大,随冷却介质温度的升高而增大.PVDF多孔膜的晶型为α晶型,该晶型不随聚合物含量和冷却介质温度发生变化.     

热致相分离法制备高聚物微孔结构材料的研究进展

热致相分离法是一种制备微孔结构材料的新方法,采用该方法可以将常温下缺少合适溶剂的高聚物制成多孔材料。为促进该方法广泛而深入的应用,文中归纳了可采用热致相分离法制备微孔膜或细胞支架的结晶性和无定型高聚物,及其所对应的稀释剂体系。综述了稀释剂种类、工艺参数(高聚物浓度、冷却条件)和添加剂等因素对热力学相图、相分离机理、微孔结构及材料性能的影响。     

热致相分离法制备聚合物微孔膜的研究进展

分别从S-L相分离和L-L相分离两方面简述了热致相分离法制备聚合物微孔膜的成膜过程.从聚合物分子量、聚合物浓度、稀释剂与聚合物的相互作用、稀释剂的流动性及结晶、冷却速度及冷却方式、萃取剂的种类及萃取剂的抽提方式、成核剂几方面总结TIPS法制膜的研究进展,并从膜材料、膜结构以及制膜方法三方面阐述热致相分离法制膜的发展趋势.     

热致相分离制备聚偏氟乙烯膜

以聚偏氟乙烯(PVDF)为基材,选用3种稀释剂邻苯二甲酸二甲酯(DMP),间苯二甲酸二甲酯(DMIP),水杨酸甲酯(MS)为稀释剂,通过热致液-固相分离制备了微孔膜.结晶度随PVDF含量的增加先增加后降低,在40%(wt,下同)时结晶度最大.结晶温度随着PVDF-MS,PVDF-DMIP,PVDF-DMP的顺序降低.考察了不同降温条件对聚偏氟乙烯膜的结构的影响.在液-固相分离的前提下,通过不同的降温条件,得到球粒堆积的微观结构.     

热致相分离法制备聚丙烯微孔膜

简述了用热致相分离（ＴＩＰＳ）法制备聚丙烯微孔膜的热力学依据,即聚丙烯／稀释剂二元体系的固－液、液－液相分离和弱相互作用体系的综合平衡相图,Ｆｌｏｒｙ－Ｈｕｇｇｉｎｓ相互作用参数对相图的影响,以及实际ＴＩＰＳ过程的非平衡相图。以此为依据,概述了ＴＩＰＳ法制备聚丙烯微孔膜的成膜机理。在上述理论基础上,综述了稀释剂与聚丙烯的相互作用、稀释剂的流动性和结晶性、初始浓度、冷却速率及成核剂对膜结构的影响。最     

混合稀释剂对热致相分离法制备等规聚丙烯微孔膜的影响

以邻苯二甲酸二丁酯(DBP)和大豆油混合物为稀释剂,利用热致相分离(ThermallyInduced Phase Separation,TIPS)法制备了等规聚丙烯(iPP)微孔膜.结果表明,稀释剂体系中DBP和大豆油的质量比对浊点温度影响较大,而对结晶温度影响较小;随着稀释剂体系中DBP含量的增加,在固定聚合物浓度及相同的冷却条件下,多孔膜由空间网状结构逐渐转变为腔胞状结构,表面孔径也有明显的增大趋势;稀释剂的加入降低了iPP球晶的生长速率,其组成对iPP球晶生长速率也有一定影响.     

热致相分离制膜条件对聚丙烯平板微孔膜结构的影响

以热致相分离法制备了聚丙烯平板微孔膜.研究了铸膜液中聚丙烯浓度、熔体指数、稀释剂和成核剂种类及含量、凝固浴温度等制膜因素及条件对膜结构的影响.采用扫描电子显微镜观测制备膜的断面及表面结构,并基于热力学和结晶动力学理论对聚丙烯成膜过程机理进行探讨,结果表明:制膜条件对聚丙烯平板微孔膜的结构影响明显.     

复合热致相分离制膜方法

系统介绍了北京坎普尔环保技术有限公司自主创新研发成功的复合热致相分离(complex Thermally Induced Phase Separation,简称为c-TIPS)制膜方法,并与经典的热致相分离(TIPS)制膜方法和修正热致相分离(m-TIPS)制膜方法作了比较.c-TIPS法以水溶性良溶剂和水溶性添加剂组成的混合物作为"复合稀释剂",在加热搅拌罐中,于聚合物熔点(Tm)以下的温度(一般为90～170℃)下形成聚合物/复合稀释剂体系的均相溶液,在相同温度或低5～10℃的温度下纺丝,通过控制芯液和冷却液的组成,利用同时或先后发生的热致相分离(TIPS)和非溶剂致相分离(NIPS)过程的复合相分离过程,制备了强度高、通量大、外表面有皮层(超滤膜)和没有皮层(微滤膜)的新型中空纤维(毛细管)多孔膜.该方法适用于几乎所有半结晶性和非结晶性制膜材料,例如,PVDF,PES,PS,PVC,PAN,PMMA,CA,等,所得膜的综合性能大大优于用NIPS法制备的同样材料的膜性能.     

混合稀释剂对热致相分离法制备聚偏氟乙烯微孔膜结构的影响

以邻苯二甲酸二甲酯(DMP)/邻笨二甲酸二辛酯(DOP)为混合稀释剂,采用热致相分离法(TIPS)制备聚偏氟乙烯(PVDF)微孔膜.研究了聚合物浓度、降温速率、混合稀释剂配比和凝固浴温度对聚偏氟乙烯微孔膜结构的影响.结果表明,随聚合物浓度的增加,膜断面由树枝状结构过渡为球粒状结构,最终转变为致密结构;随降温速率的增加,...     

热致相分离法制备纳米碳酸钙/聚偏氟乙烯共混膜

以邻苯二甲酸二丁酯(DBP)为主要稀释剂,添加无机粒子CaCO3,采用热致相分离法(TIPS法)制备了聚偏氟乙烯/碳酸钙(PVDF/CaCO3)共混膜。考察了不同冷却条件对共混膜的影响以及CaCO3含量对聚偏氟乙烯结晶温度、结晶度的影响;研究了酸处理对共混膜微观结构、力学性能的影响。实验表明,通过改变冷却条件可以控制球晶的大小以及膜表面皮层的厚度;随着CaCO3含量的增加,PVDF共混膜的水通量先增加后减少,拉伸强度不断增加。经酸处理之后,共混膜水通量显著提高,拉伸强度有所下降。     

Polyethylene glycol compounds for functional hydraulic fluids

New compounds of phthalate; -phosphate, -borate, -phosphate-borate; polyethylene glycol and 2-(2-butoxy ethoxy ethanol) were synthesized, with the aim of producing new high performance functional hydraulic fluids. The synthesis process involves two stages: first, the synthesis of base compounds which are products of the reactions of phthalic acid anhydride, polyethylene glycol and acid [phosphoric, boric, phosphoric-boric and/or phthalic]. Then, the reaction of phthalic acid with 2-(2-butoxy ethoxy) ethanol. The base compounds so prepared, together with diluents and additives were formulated for the second stage of the synthesis process. The effectiveness of standard specification tests was investigated. Property improvement may be attained by the incorporation of phthalic acid anhydride in the reaction. Our new functional hydraulic fluids can be produced more economically and can monitor any pollution caused by fluid operations in the petroleum industry. Electronic Publication     

Effect of diluent upon the properties of a visible-light-cured dental composite

Four long-chain aliphatic organic diluents, triethylene glycol dimethacrylate (TEGDMA), ethylene glycol dimethacrylate (EDMA), triethyleneglycol diacrylate (TEGDA) and tetraethylene glycol diacrylate (TTEGDA) were used as diluents for preparing a visible-light-cured dental composite. Cured samples of pastes prepared using the above diluents were stored separately for a period of 60 days in distilled water at 37°C and tested for changes in compressive strength, diametral tensile strength and microhardness at specific intervals of 1, 7, 14, 21, 28 and 60 days. Samples prepared using TEGDMA showed better strength values initially compared with the composite specimens prepared using the rest of the diluents although they are found to deteriorate slowly upon storage in distilled water up to 60 days. Samples prepared using EDMA showed retention in properties whereas samples prepared using TEGDA and TTEGDA showed large deviations in strength values during the first 28 days, did not deteriorate further and were found either to show improvement upon ageing or to remain constant. Sorption values seem to reach a maximum for all composites and then to decrease further after 14 days whereas solubility is found to increase with time.     

超支化预聚物在特种UV固化胶中的应用研究

以乙二胺(EDA)、三羟甲基丙烷三丙烯酸酯(TMPTA)为主要原料,合成外围带有8个双键的超支化预聚物,用红外光谱进行了表征.将超支化预聚物与不同官能度单体配成特种UV固化胶,测定了粘度、透过率、折射率随固化胶成分的变化.结果表明,由于超支化预聚物与一般线性预聚物结构不同,UV固化胶黏度较低,且随着单体含量的增加,黏度下降平缓;在400～1500hm的可见及红外光区,UV固化胶的光透过率较高,均大于95%;UV固化胶折射率随预聚物含量的增加而增加,最高达1.572.用超支化预聚物制备的特种UV固化胶有望在光学器件中得到应用.     

An improved process for polyvinylidene fluoride membrane preparation by using a water soluble diluent via thermally induced phase separation technique

Polyvinylidene fluoride (PVDF) membranes without surface pores were prepared by using water soluble diluents, diethylene glycol monoethyl ether acetate (DCAC), via thermally induced phase separation (TIPS) technique. The effects of PVDF concentration, temperature of coagulant and DCAC concentration in coagulation bath on membrane structures and properties were studied. The antifouling property of membrane with or without surface pores was compared by humic acid (HA) solution and the recovery of DCAC in aqueous solution was investigated. Membranes were characterized by porosity, pure water flux and retention to bovine serum albumin (BSA). Membrane structures were inspected by SEM. The crystal forms of membranes were analyzed by FTIR and XRD. The results show that a compact skin layer and a support layer with spherulitic structure form when DCAC is diluent. Higher polymer concentration and higher coagulation temperature promote the formation of α phase crystal, while higher DCAC concentration in coagulation bath promotes the formation of β phase crystal. Membrane without surface pores has better antifouling property than the membrane with surface pores. Dichloromethane is the best extractant to recover DCAC in DCAC aqueous solution.     

Polymers with pH-Dependent Solubility: Possibility of Use in the Formulation of Gastroresistant and Controlled-Release Matrix Tablets

Polymers usually utilized for gastroresistant film coating of tablets or pellets such as cellulose acetate phthalate (CAP), cellulose acetate trimellitate (CAT), hydroxypropylmethylcellulose phthalate (HPMCP), and Eudragit L and S were used in the preparation of drug/polymer matrix tablets. These tablets were prepared either by direct compression of both powders or by the formulation of microspheres that were then compressed. The microspheres were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry analyses. Dissolution studies were finally carried out to verify if the tablets possessed gastroresistant or controlled-release characteristics. Except for Eudragit L, the polymers can be used under certain conditions in the formulation of modified-release tablets.     

Polymers with pH-dependent solubility: possibility of use in the formulation of gastroresistant and controlled-release matrix tablets

Polymers usually utilized for gastroresistant film coating of tablets or pellets such as cellulose acetate phthalate (CAP), cellulose acetate trimellitate (CAT), hydroxypropylmethylcellulose phthalate (HPMCP), and Eudragit L and S were used in the preparation of drug/polymer matrix tablets. These tablets were prepared either by direct compression of both powders or by the formulation of microspheres that were then compressed. The microspheres were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry analyses. Dissolution studies were finally carried out to verify if the tablets possessed gastroresistant or controlled-release characteristics. Except for Eudragit L, the polymers can be used under certain conditions in the formulation of modified-release tablets.     

Alkylphenols and phthalates in bottled waters

The aim of this study was to investigate the occurrence of endocrine disrupting compounds (EDCs) in bottled waters. The examined compounds were bisphenol A (BPA), nonylphenol (NP), tert-octylphenol (tOP), dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), di(2-ethylhexyl)phthalate (DEHP) and di(n-octyl)phthalate (DNOP). The presence of EDCs in bottled waters under poor storage conditions was also investigated after exposure outdoors under realistic conditions for 15 and 30 days. EDCs were recovered after liquid-liquid extraction and determined by employing Gas Chromatography-Mass Spectrometry. Most of these compounds were detected in bottled water from different brands purchased from local market. Storage at outdoor conditions had no significant effect on the concentrations of the examined compounds. Only BPA occurred at higher concentrations in polycarbonate containers exhibited an increasing trend during exposure. The estimated exposure to EDCs via consumption of drinking water was very low.