Studies on Morphology and Thermomechanical Behavior of Polyethylene Glycol/1,8-Octanediol-modified Epoxy-organoclay Hybrid Nanocomposites

Abstract

Organoclay-filled polyethylene glycol (PEG)/1,8-octanediol (OCT)-modified epoxy matrices were developed. Epoxy systems modified with 10, 20, and 30 wt% of PEG/OCT were made by using diglycidyl ethers of bisphenol A epoxy resin and PEG/OCT with 4,4′-diaminodiphenylmethane as curing agent. The PEG/OCT-modified epoxy systems were further modified with 1, 3, and 5 wt% of organoclay. The thermal behavior of organoclay-filled PEG/OCT-modified epoxy matrices were characterized using differential scanning calorimeter, thermogravimetric analysis, and dynamic mechanical analysis. Mechanical properties were studied as per ASTM standards. Three percent organoclay-filled PEG-modified epoxy possesses high storage modulus (6240 MPa) compared to 3% organoclay-filled OCT-modified epoxy (5064 MPa). The values of impact strength for 3% organoclay filled PEG and OCT modified epoxy systems are 122 and 85.5 J/m, respectively. Homogeneous and heterogeneous morphology was ascertained from scanning electron microscope. From the X-ray diffraction analysis, it was observed that the absence of d001 reflections in organoclay-filled PEG/OCT-modified epoxy systems indicated the formation of exfoliated nanohybrids. The significant improvement in impact strength was achieved without any reduction in glass transition temperature (Tg) due to the addition of organoclay. Thermal stability with better char yield and improved impact strength were attained during the formation of nanocomposites due to the increment of organoclay in PEG/ OCT-modified epoxy systems.