Structure-property relationships of polymer blend/clay nanocomposites: Compatibilized and noncompatibilized polystyrene/propylene/clay

A direct functionalization of polyolefins for blend compatibilization by an insertion of 1,1-bis(phenylsulfonyl)ethylene (BPSE)

A mild post-modification of polyethylene (PE) & polypropylene (PP) to insert phenylsulfonyl groups is reported, the modified samples demonstrated to act as blend compatibilizers.

Morphological characterization, thermal, and mechanical properties of compatibilized high density polyethylene/polystyrene/organobentonite ternary nanocomposites

Composite materials made from high density polyethylene (HDPE) and polystyrene (PS) were successfully prepared in different HDPE/PS weight ratios, by melt mixing 3 wt% of bentonite clay organically modified with hexadecyl ammonium chloride (organo-modified bentonite, OBT). The structure and morphology of these composites were examined by X-ray diffraction and scanning electron microscopy. Morphological changes between the composite and the constituent materials were observed. The decrease in PS (or HDPE) particle size in HDPE/PS 70/30 (or 30/70) that blend after the OBT addition reflects a clear improvement in the HDPE/PS blend compatibility. The effect of OBT on the thermal and mechanical properties was investigated by differential scanning calorimetry, thermogravimetric analysis, and tensile measurements. The main results show a decrease in the HDPE crystallinity in the composite matrices, which reaches 25% for HDPE/PS/OBT 29/68/3 composite, also an improvement of the thermal stability, as evidenced by the higher T onset values, and finally a reinforcement of the tensile properties as compared to the unfilled blends. Indeed, a significant enhancement of the tensile modulus (~130%) is observed for the 68/29/3 composite matrix as compared to the 70/30 unfilled blend.

Effect of the Addition of ENR on Foam Properties of EVA/NR/Clay Nanocomposites

Elastomeric foams based on 60/40 EVA/NR blend nanocomposite were prepared by melt mixing EVA, NR and clay (5 phr) in an internal mixer, and later foamed with azodicarbonamide through compression molding. Epoxidized natural rubber (ENR) with epoxide content of 25 mole% was used as a compatibilizer to improve interfacial adhesion between EVA and NR. The addition effect of ENR concentration on the blending and properties of EVA/NR blend nanocomposite foams was studied. XRD and TEM results showed that the clay in the EVA/NR blends was intercalated and locally existed in the NR phase as well as at the interface between EVA and NR. The EVA/NR blend nanocomposites showed dispersed NR domains in continuous EVA phase. The addition of ENR into EVA/NR blend nanocomposites reduced the size of the dispersed NR phase, indicating that the blend miscibility was improved. Mechanistic model was proposed for the miscibility improvement of a two-phase structure of EVA/NR blend nanocomposite in the presence of ENR and clay dispersion. However, the improved blend morphology did not significantly affect the cell structure of EVA/NR blend nanocomposites. The observation of cell structure of EVA/NR blend nanocomposites suggested that the increased addition of ENR caused a little increase in cell density, and had no influence on cell size. Furthermore, with increasing addition level of ENR in the blend nanocomposite foams, the foam density slowly decreased, whereas the specific tensile strength slightly increased. The elastomeric recovery of blend nanocomposite foams decreased with increasing ENR content. The thermal conductivity of EVA/NR blend nanocomposite foams also decreased with more addition of ENR, which had beneficial result in improving thermal insulation property.