One of fluorinated polyimides was synthesized from 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 3,3′-dimethyl-4,4′-diaminodiphenylmethane (DMMDA) by two-steps method, which had good solubility and hydrophilicity. 6FDA-DMMDA polyimide was dissolved in chloroform (CHCl3) and cast on a glass substrate in a humid atmosphere. It was found that 6FDA-DMMDA/CHCl3 solution was easy to form ordered porous structure at high concentration, and the reason was discussed in detail. In addition, the influences of solution concentration, the atmosphere humidity, were also tested. 相似文献
In this study, in-situ compatibilized polymer blends of polypropylene (PP) and poly (butyl methacrylate-co-hydroxyethyl methacrylate) P(BMA-co-HEMA) were prepared in a corotating twin screw extruder through the reactive extrusion of mixtures of PP, P(BMA-co-HEMA), butyl methacrylate, and benzoyl peroxide. In the process of reactive extrusion, butyl methacrylate and benzoyl peroxide were used as the monomer and the initiator, respectively. Thereafter the polymer blend was made into fibers via melt spinning. The miscibility of PP and P(BMA-co-HEMA) in the blend fibers was investigated using field emission scanning electron microscopy. The absorption percentage of the blend fibers for organic liquids and their remaining ratios after the absorption tests were also determined and used to prove the generation of the third phase. The changes in the fiber morphology during organic liquid absorption were observed using polarized light microscopy. In addition, the effect of the miscibility on the crystal structure and melting characteristic of the blend fibers were analyzed using wide-angle X-ray diffractometry and differential scanning calorimetry. Finally, the thermal stability of the blend fibers that was associated with the miscibility of PP and P(BMA-co-HEMA) in the blend fibers were characterized by using thermogravimetry and dynamic thermomechanical analysis. 相似文献
Herein, cellulose nanofibrils (CNF), alkali lignin (AL), and montmorillonite (MMT) were used to produce reinforced polyvinyl alcohol (PVA) hydrogels. The effects of MMT and AL contents on the rheological properties of reinforced hydrogel were studied. Compared with PVA/CNF hydrogel, the storage modulus of 40 wt% MMT-reinforced PVA hydrogel was increased by 41.4%. The rheological properties of MMT-enhanced PVA hydrogel could be adjusted by the variation of MMT loading. Also, as the PVA matrix had a synergistic effect with the embedded MMT and AL, the composite hydrogel demonstrated high efficiency in the removal of methylene blue dye (MB) from wastewater. Adsorption tests conducted at various time intervals (60–360 min) show that the hydrogels containing same content of MMT had higher removal efficiency. The MB adsorption of PVA/2CNF-0Li-40MMT was over 98.0%, whereas its adsorption equilibrium time and maximum adsorption capacity (qm) were 360 min and 67.2 mg/g, respectively. However, an extremely high content of MMT reduced the MB adsorption rate.
Butyl methacrylate-butyl acrylate-acrylic acid terpolymer was synthesized by suspension polymerization with benzoyl peroxide as an initiator and poly(vinyl alcohol) as a dispersing agent to absorb organic liquids, and then the terpolymer was modified to absorb distilled water, NaCl aqueous solution, and toxic metal ions by swelling in isopropyl alcohol and hydrolysis in sodium hydroxide aqueous solution. The morphology changes during the liquid absorption process were observed via a polarizing light microscope. The thermostabilities of the original and modified terpolymers were tested in a thermogravimetric analyzer. The test results indicated that the unmodified terpolymer could absorb a certain amount of toluene, trichloroethylene or tetrachloroethylene to become a swollen system, and its remaining (residual) ratio was more than 75% after absorbing the organic liquids for 24 h. The modified terpolymer not only had a marked capacity to absorb distilled water and NaCl aqueous solution, but also showed a significant absorption of toxic metal ions; e.g., its saturated absorbency of Cu2+ could reach 421.0 mg/g. The morphology changes demonstrated that the modified terpolymer could be swollen in distilled water, forming a gel-like structure. The results obtained from thermogravimetric analysis revealed that the thermal stability of the modified terpolymer was better than that of the unmodified terpolymer. 相似文献