Papers by Author: Xin Xin Nie

Abstract: By means of melt blending process in a co-rotating twin screw extruder with two-step process, the low density polyethylene (LDPE)/ethylene octene copolymer (POE)/zeolite molecular sieves (ZMS) composites were prepared. The influence of ZMS on the crystallinity, mechanical properties and permeability was investigated by differential scanning calorimetry(DSC), universal testing machine and permeability tester, respectively. The results showed that the addition of ZMS made the crystallinity of composite film decreased and the growth rate of crystal nucleus promoted. As the content of ZMS rose, the mechanical properties of composite film decreased, while the CO₂, O₂ permeability and the moisture permeability increased.

Abstract: By mixing PEG or LiCl respectively into the casting solution, the polyurethane (PU)/SiO2 hybrid membranes were prepared by means of immerged phase inversion process. The method of NMR relaxation time T1 value was used to determine effect of the segmental movement of PU macromolecule in the casting solution on the microporous structure of membrane. The membrane section photos of SEM and properties of the PU hybrid membranes were investigated respectively. The results showed that blending SiO2, and with LiCl or PEG into the PU solution system, the T1 value synchronistically decreased. That was relaxed of PU chain winding and ease to move. The additives of PEG could influence the casting solution of PU, it enhanced the distribution of SiO2 in the casting solution, and formed fine interfacial micropores, meanwhile the retention of the membranes were increased to certain degree whereas the pure water flux could kept at a higher level. Similarly, adding some quantity of LiCl could obtain the membrane with higher retention under the condition of slightly loss of pure water flux. Even thought that there were equivalent quantities of finger pores in section of membrane, mixing PEG or LiCl in the casting solution, the SEM section photos indicated that there were more micropores in the wall of pore.