Nanocomposites from poly(methyl methacrylate) (PMMA), silica (SiO2) and zirconia (ZrO2) were prepared using a novel nonhydrolytic sol-gel process. Silicic acid and zirconium oxychloride (ZrOCl2 8H2O) were used as the precursors of SiO2 and ZrO2, respectively. FT-IR and SEM results showed that nanometre-scaled SiO2/ZrO2 particles were uniformly distributed in and covalently bonded to the PMMA host matrix without macroscopic organiceinorganic phase separation, which was also confirmed by solvent extraction experiments. It was found that the transmittance of the nanocomposite films in the visible region remained above 95% even at 20wt% inorganic content and increased proportionally with decreasing inorganic content. The thermal stability and the thermal decomposition kinetics of the composites were studied. The results indicated that the activation energy (Ea) of the thermal decomposition of PMMA main chains in the composites was increased due to the addition of inorganic moieties. This kind of composite material may have the potential for applications in optical devices.

The phase diagrams of various ethylene-vinyl alcohol (EVAL) copolymer with different hydroxyl (OH) group contents and poly(ethylene glycol) (PEG) with different molecular weights (ranging from 200 to 600) are determined. It is found experimentally that both the liquid-liquid (L-L) phase boundaries and the crystallization curves are shifted to higher temperature when the OH group contents in EVAL increase. On the other hand, only the L-L phase boundaries shift to higher temperature when the molecular weights of PEG increase. These phenomena are interpreted by using solubility parameters (δd, δp) to estimate the Flory-Huggins interaction parameters, χ*, of the mixtures. By extrapolating the L-L bi-phasic curves from cloud points of temperature (Tcloud), the experimental interaction parameters χ* are obtained, which are linearly correlated to the theoretically estimated interaction parameters, χ*.

Anewmethod to synthesize polyimide (PI)/silica nanohybrids has been presented. It uses silicic acid oligomer as the silica precursor, which was obtained by extracting with tetrahydrofuran (THF) from PH-adjusted water glass. The films of PI/silica nanohybrids remained transparent even at high silica content due to the formation of nanometer-scaled SiO2 particles at the addition of γ-aminopropyltriethoxysilane (APTES). In comparison with pure PI, PI/silica hybrids showed improved thermal stability and mechanical properties, and lower linear coefficients of thermal expansion (CTEs). The glass transition temperatures of the hybrids were increased with increasing content of silica or APTES as a result of the increasing limitation to the movements of the PI backbone.

The polyamide-6/attapulgite nanocomposites were prepared via an in situ polymerization route with attapulgites pre-modified with cetyltrimethylammonium bromide (CTAB) and toluene-2,4-diisocyanate (TDI). Morphology observation showed that the exfoliated attapulgite fibers were well dispersed in the polyamide-6 matrix on a nanometer scale and formed a percolation network structure. The rheological behaviors of such polymer/fibrous clay nanocompostie samples were investigated by an ARES rheometer with parallel plate geometry. The storage moduli (G0), loss moduli (G00), and dynamic viscosities of these samples increased monotonically with attapulgite content at low frequencies. The presence of attapulgites caused these nanocomposite melts to have solid-like behaviors and slower relaxation. This behavior can be explained in terms of the development of a grafting-percolated fibrous-silicate network structure. Monte Carlo simulations were performed to determine the critical threshold for attapulgites fibers in 3D. The calculated critical threshold from simulations fitted the results of our rheological experiments very well.

A novel process to prepare microporous hollow fiber membranes is proposed. Fibers of blends of isotactic polypropylene (i-PP) and atactic polypropylene (a-PP) spun under high take-up draw ratio are found to be elastic. Small angle X-ray scattering (SAXS) observation indicates that fibers have row-nucleated lamella structure normal to the fiber direction. Microporous polypropylene hollow fiber membranes were obtained from the fibers by extraction of atactic polypropylene and cool-stretching. The membranes have smaller pore size and higher permeability than those of traditional stretch method. The mechanism of micropore formation is discussed.