Nanocomposites of Polyethylene Blends Using Organomica

Abstract

This study aims to incorporate LLDPE into HDPE in order to improve its processability, as well as to employ a nanoclay for maintaining the HDPE stiffness. Thermal, dynamic-mechanical and rheological properties of polyethylene composites were investigated. Muscovite mica was treated with lithium nitrate for seven cycles, followed by exchange with quaternary ammonium salt to produce organomica. Initially, organomica was added to HDPE at 2% wt. using a tweenscrew mini-extruder. The blend HDPE/LLDPE (1:1 by weight) was also evaluated at the same mica content, with and without the introduction of maleated polyethylene (PEMA) as compatibilizer in order to increase adhesion of polymers with the mineral clay. The samples were evaluated by thermogravimetry (TGA), while melting and crystallization temperatures, and the degree of crystallinity were measured by differential scanning calorimetry (DSC). Rheological properties were evaluated during blending using viscosity and torque curves as a function of processing time. The results showed that stability to thermal degradation of the polyethylene blend with mica increased with the addition of 2% wt. PEMA, where the temperature of maximum degradation rate overcame that of HDPE. The melting endotherm remained narrow in the mixture HDPE/LLDPE/mica, showing good miscibility of the polymer blend; and there was a slight decrease in the melting temperature. The reduction in viscosity during blending revealed improved processing conditions.

Effect of filler particle shape on plastic-elastic mechanical behavior of high density poly(ethylene)/mica and poly(ethylene)/wollastonite composites

“…It was found that with increasing filler concentration the crystallinity of the HDPE in HDPE/mica composites increased from 59 % for virgin HDPE to 77 % for 15 w. % HDPE/mica composite, indicating a positive effect of the mica nano-sheets planar crystalline facets on HDPE crystallization in a similar fashion as in the case of other planar filler materials such as clay [6,21]. The observed maximum thermal degradation rate of the HDPE/mica composites found was about 467 °C, which was in agreement with the earlier published data [46]. On the other hand, the crystallinity decreased from 62 % obtained for virgin HDPE to 56 % for the 15 w. % HDPE/wollastonite composites.…”

Effect of fiber and polymer variability on the rheological properties of wood polymer composites during processing

“…The fusion properties of the pellets of wood-HDPE particles (25,35, and 45% of wood particles by weight) were measured using a Haake PolyLab OS: Rheomex CTW 100 OS (Thermo Electron GmbH, Karlsruhe, Germany). The torque rheometer re-mixed the HDPE and the fibers while measuring the torque required at each step of blending.…”

“…This result is explained by the shear stress behavior during the mixing process. The internal mix slippage leads to more friction which contributes to the temperature increase [35]. Species and origin affected the wettability of the wood fiber and its incorporation in the polymer.…”