The properties of metallocene polyethylene (mPE)/polylactic acid (PLA) bio-based blends containing an ethylene-glycidyl methacrylate-vinyl acetate (EGMA-VA) compatibilizer, with or without the annealing effect of PLA were investigated. The results from SEM (Scanning electron microscope) morphology observation revealed that the dispersed PLA particles sizes within the mPE matrix tended to decrease with the added compatibilizer due to the enhanced interfacial interaction. DSC (Differential scanning calorimetry) and XRD (X-ray diffractometer) results indicated that the addition of the compatibilizer completely hindered the cold crystallization and rearrangement crystallization of PLA, even though the additional annealing effect tended to increase the crystallization of PLA. Tensile test results showed the synergistic effects by compatibilization and annealing treatment improved the tensile strength and Young's modulus, up to 38 % and 62 % increase, respectively. With the incorporation of the compatibilizer, the viscosity increased and reached the highest level among all neat resins and blends, which was attributed to the enhanced interfacial interaction between mPE and PLA. Hopefully, the incorporated bio-based PLA materials could be helpful in reducing the use of petroleum-based materials and are beneficial to the environment in terms of the sustainable development concern.
Silver-coated PAN nanofibers have been prepared by a facile method that combined the electrospinning technique and electroless plating method. Dopamine was used to functionalize the surface of electrospun PAN nanofibers to form the chemisorption sites in order to assist electroless plating of silver. SEM and ATR-FITR results indicated that poly(dopamine) has been successfully deposited on the surface of PAN nanofibers. XRD and SEM results also showed that face-centred cubic (fcc) crystal Ag nanoparticles with uniform size were well coated on the surface of electrospun PAN fibers.
Nanofibrous substrate composite ultrafiltration membrane consisted of polyacrylonitrile (PAN) electrospun scaffold which was used as the substrate, and a thin crosslinked poly(vinyl alcohol) (PVA) barrier layer which was prepared by electrospinning technique combined with mixed solvent treatment. The thickness of PVA nanofibrous top layer was controlled by changing the electrospun depositing time. Through immersing PVA/PAN double-layer mats into water/acetone mixed solvent system, the PVA nanofibrous top layer was swollen to merge imperceptibly into an integrated barrier film on the surface of PAN substrate, and then chemically crosslinked by glutaraldehyde. The resultant PVA/PAN thin film nanofibrous composite (TFNC) membrane has high rejection rate (99.6%), high flux (410.5l/m2h) and good anti-fouling characteristic at very low operation pressure (0.2MPa) for separating oil from the oilfield wastewater. Additionally, the removal of TDS, suspended matter, total iron and sulfate reducing bacteria (SRB) showed high rejection rate with relatively stable PH.
Thin-film nanofiltration composite (TFNFC) membrane consisting of polyethersulfone (PES) nanofibrous support layer modified by 3, 4-dihydroxy-phenethylamine (dopamine) and interfacial polymerization (IFP) polyamide selective barrier layer was obtained in this study. The hydrophilicity of PES nanofibrous membrane was tremendously improved as the water static contact angle changed from 81.6° to 26.83° by dopamine modification. An ultrathin selective layer was produced by IFP reaction between solutions of piperazine (PIP) and trimesoyl chloride (TMC) on the dopamine modified porous PES membrane. The TFNFC membrane presented relatively high permeate flux (~59.9 L/m2h) and high salt rejection (~98.9%) to divalent anion solutions (1000mg/L, Na2SO4) at a low pressure of 0.6 MPa. It could be believed that dopamine modification would be very efficient to fabricate the composite membranes with stable structure and high filtration performance.
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