Permeability, Melt Flow Index, Mechanical, and Morphological Properties of Green HDPE Composites: Effect of Mineral Fillers

Abstract

In this study, two types of composites, both with the same polymeric matrix, high density polyethylene (HDPE) from renewable sources, also called green HDPE, are investigated. The mineral fillers insert into HDPE are vermiculite and titanium dioxide (TIO2). The objective of this work is the evaluation of two inorganic fillers in the HDPE composites and how their presence alters the properties of this HDPE derive from sugar cane ethanol. Composites obtain by extrusion with different contents of anatase type titanium dioxide (10–30 wt%/wt) and brazilian vermiculite (5–20 wt%/wt) are evaluated as for mechanical and morphological properties, melt flow index (MFI), and permeability. The addition of fillers cause little influence on tensile strength, but increased the elasticity modulus and decreased impact strength. in relation to morphology, it is found that particles of TIO2 are well dispersed in the HDPE matrix. For composites with vermiculite, its distribution in the polymer matrix is not so good as compared with composites of TIO2, especially in proportions higher than 10 wt%. The results of MFI show that by adding vermiculite the fluidity of polyethylene does not change, but the addition of TIO2 promotes a reduction in fluidity thus suggesting that a good dispersion has been achieved. Permeability increases on the addition of the two fillers, being more pronounced at high amounts (20% vermiculite and 30% TIO2). The analyzed properties, the addition of these fillers does not interfere negatively the properties of the green HDPE and can be considered an alternative toward low cost composites.

The Relationship between a Rotational Molding Processing Procedure and the Structure and Properties of Biobased Polyethylene Composites Filled with Expanded Vermiculite

“…The general chemical structure of vermiculites is X 4 (Y 2–3 )O 10 (OH) 2 M·nH 2 O, where X is a Si or Al, Y is Mg 2+ , Fe 2+ or Fe 3+ , Al 3+ and M is an exchangeable by Mg 2+ , Ca 2+ , Ba 2+ , Na + , and K + . X responds to a tetrahedral sheet, which is usually silica, and Y responds to an octahedral, usually magnesia [ 26 , 27 ].…”

“…There are reports on polyethylene–vermiculite composites based on bio-high-density polyethylene in the literature. These materials have been tested to investigate permeability, which does not deteriorate significantly after adding vermiculite [ 26 ]. The bio-polyethylene with vermiculite can be formed into a flat film in which the increase in hydrophilicity is observed with the increasing amount of vermiculite.…”

“…This means that there are limited interactions between these two phases. In most cases, filler treatment needs to be performed to improve the bonding of vermiculite in the PE matrix [ 26 ]. The vermiculite treated with an ionic surfactant becomes the organophilic filler, which helps obtain an even distribution of this filler in PE and modify its fire behavior [ 29 ].…”