Surlyn (R)/[silicon oxide] hybrid materials. 2. Physical properties characterization

The influence of an in situ-grown, sol --> gel-derived silicon oxide filler on mechanical, gas permeation and solvent affinity properties of Surlyn(R) materials, and melt processibility of Surlyn(R)/[silicon oxide] hybrid res in, was studied. Tensile modulus increases while elongation-at-break decrea ses with increasing silicon oxide uptake. He gas permeation vs. pressure pr ofiles imply dual mode sorption. Swelling in n-hexane, 1-PrOH and xylene de creases as silicon oxide loading increases, the highest uptake being that o f xylene. [Surlyn(R)Zn+2]/[silicon oxide] has better solvent resistance tha n the H-form hybrid for each solvent. Affinity of the Zn-form hybrid for xy lene is considerably greater than that for 1-PrOH and n-hexane. Melt flow i ndex of the filled H-form is lower than that of the unfilled H-form but hig her than that of the partially Zn neutralized unfilled form. FTIR analysis of hybrids previously subjected to the melt flow index experiment shows tha t the silicon oxide phase remained intact but that the high temperatures dr ove condensation reactions between SiOH groups. After in situ sol-gel react ions and drying [Surlyn(R)-H]/[silicon oxide] flakes were passed through an extruder to assess the effect on silicon oxide structure of melt-processin g conditions. All silicon oxide IR fingerprint bands for the processed hybr id persist, the spectrum closely resembling that of a nonextruded hybrid in cluding the signature of Si-OH groups. Si-29 solid-state NMR spectroscopy w as used to probe degree of molecular connectivity within the silicon oxide phase. The spectrum is consistent with those of nonextruded hybrids in that Si atom coordination around SiO4 units is predominantly Q(3) and Q(4), the bias in the distribution toward Q(3) being in harmony with the IR results. (C) 1999 John Wiley & Sons, Inc.