Confinement and nucleation effects in poly(ethylene oxide) melt-compounded with neat and coated sepiolite nanofibers: Modulation of the structure and semicrystalline morphology

Composites have been prepared by melt compounding poly(ethylene oxide) with neat sepiolite, sepiolite coated with polyethylene glycol and with d-α-tocopherol polyethylene glycol 1000 succinate. It has been found that the nature of the sepiolite surface and its ratio in the composite enable the modulation of interfacial (nucleation) and confinement phenomena, both of which have distinct and opposed effects on the polymer’s crystalline phase. The modulation of both phenomena allows to tune the final morphology and structure of the polymer, this tuning including spherulite size, orientation of the crystalline lamellae, tortuosity of the crystalline phase, chain conformational disorder, glass transition temperature and pre-melting α′relaxation. Some of these modifications are thickness dependent, what is frequently found when the semicrystalline morphology of polymers is altered by its confinement into micrometric domains. Basic properties of the polymer such as elastic modulus and gas permeability are seen to depend very strongly on the morphology and structure modulation.