Achieving Dual-Functionality by Surface Coating of Zeolite with Stearic Acid: Combining Breathability and Odor Control Properties in Polyethylene/Zeolite Composite Films

Abstract

This study was aimed at providing both water vapor permeability and hydrogen sulfide adsorption properties in polyethylene (PE) stretched films by using different amounts of natural zeolites. Firstly, zeolite was coated with 1%, 5%, and 7% stearic acid in a high shear mixer. Cup test, Fourier transform infrared (FTIR) spectroscopy, and ash-oven analyses showed that a succesful coating was achieved. According to the Brunauer, Emmett and Teller (BET) gas adsorption and inductively coupled plasma mass spectrometer (ICP-MS) analyses, surface treatment with stearic acid didn’t change the particle size of the zeolite but lowered its hydrogen sulfide (H2S) adsorption capacity from 38.84±5.22 ppm/g sample (uncoated zeolite) to 17.26±2.54 ppm/g sample (7% coated zeolite]. PE/zeolite (80/20 and 60/40 w/w] blown films were generated by using uncoated and 1%, 5%, and 7% stearic acid coated zeolites and then stretched. It was observed that the stearic acid coating of zeolite greatly improved the compatibility between polyethylene and zeolite resulting in films without pinholes generation after stretching (especially the 7% coated zeolite containing PE/zeolite (60/40 w/w) film). The usage of coated zeolite also improved mechanical properties by increasing the tensile strength and decreasing the elongation at break values. It was revealed that a loading amount of 40 wt% coated zeolite was necessary for achieving a sufficient breathability (658±4 and 1040±3 g/m2/day for 5% and 7% coated zeolite containing films, respectively). Odor removal capacity of the PE/zeolite (60/40 w/w) films was improved by 165% and 244% for the 5% and 7% coated zeolite containing samples, respectively.