Tunable water barrier properties of EVA by clay insertion?

Abstract

Organo-modified Cloisite clays at varying contents were incorporated into poly(ethylene-co-vinyl acetate) (EVA) by melt blending. Nanoclay dispersion in films was first evaluated. The water transport properties were investigated by pervaporation and sorption measurements. A decrease of the water permeation flux was obtained when incorporating nanoparticles. This barrier effect is usually attributed to the increase of the diffusion pathways due to nanoclay-induced tortuosity effects. However, the diffusion coefficient was found to be dependent on water concentration, which generally reflects a plasticization effect of water. Besides, at 7 wt% of loading, an unexpected increase of water diffusivity was measured with a time-scale shift of the permeation flux. This was correlated with the formation of preferential diffusion pathways along interfacial regions due to free volumes existing between the EVA matrix and nanoclays as well as the water affinity of microfillers. As a consequence, water mass gain was found to be increased. The water-induced plasticization of sorbed water molecules was also highlighted through sorption kinetics. Eventually, some applications to these films in which water barrier behaviour is required were discussed.

The relationship of structure, thermal and water vapor permeability barrier properties of poly(butylene succinate)/organomodified beidellite clay bionanocomposites prepared by in situ polycondensation

“…The diffusion coefficient can be calculated from Fick's second law for gaseous diffusion in a planar sheet as: [53][54][55][56]…”

“…This can be attributed to specic interactions (hydrogen bonds) between incoming water molecules and polar groups (ester functions) of polyester chain backbone, increasing the water affinity of the lm, and therefore its weight gain. 55,56 On the other hand, the addition of 3CTA-BDT organoclay ller reduces the absorption of vapor compared to the pure PBS. Due to its hydrophobic character (modication with CTAB surfactant) and its lamellar structure, 3CTA-BDT organoclay reduces the sorption and the diffusion of vapor and thus acts as a barrier for the water diffusion.…”

Development of Ethylene-Vinyl Acetate Composites Reinforced with Graphene Platelets

“…One of the most straightforward routes to overcome the abovementioned challenges is to incorporate nanofillers such as clay minerals, titania, alumina, graphite, and its derivatives, etc., into polymer matrices. As for EVA copolymers, the addition of diverse types of clay minerals has been deeply researched .…”

Layered Double Hydroxides (LDHs)

“…Therefore, the intercalation molecules are placed in a wiggle shape around the nanoparticles in a random way [166,167] as seen in Figure 18b. Follain et al [169] investigated the water vapor transport properties by pervaporation and sorption measurements and evaluated nanoclay extent of dispersion in polymer matrix. They prepared nanocomposites based on poly(ethylene-co-vinyl acetate) (EVA)/organo-modified Cloisite clays at varying contents by melt blending.…”