EVOH/clay nanocomposites produced by melt processing
2001; Wiley; Volume: 22; Issue: 5 Linguagem: Inglês
10.1002/pc.10573
ISSN1548-0569
AutoresN. Aktzi, Y. Nir, D. Wang, M. Narkis, A. Siegmann,
Tópico(s)Polymer Nanocomposite Synthesis and Irradiation
ResumoAbstract Ethylene‐vinyl alcohol copolymer(EVOH)/clay nanocomposites were prepared via a dynamic melt‐intercalation process. The phase morphology and the crystallization behavior of the nanocomposites were investigated, using DSC, DMTA, XRD and SEM. It was found that the treated clay content and dynamic processing time affect the viscosity of the EVOH/clay mixtures: higher clay contents and longer mixing times result in higher torque/viscosity levels. This is due to the increased interaction of the molten polar matrix (EVOH) with the treated organosilicate surface. Under the dynamic high shearing forces, the polymer penetrates the clay agglomerates/aggregates, intercalates within the organoclay galleries, and finally causes delaniination. Thermal analysis of the EVOH/clay nanocomposites showed that the melting temperature, crystallization temperature and heat of fusion of the EVOH matrix, sharply decrease with increasing both, the clay content and processing time. The intercalation level was characterized by X‐ray diffraction (XRD), which verified an increased gallery height. The DMTA spectra showed that longer processing times resulted in higher damping (E″ intensity) levels of the EVOH/clay composites, indicating higher fractions of the EVOH amorphous phase. However, no Tg changes were seen in spite of the high polymer/treated clay interaction levels, which may be attributed to a plasticizing effect of the low molecular weight organic cations.
Referência(s)