Thermal and mechanical behavior of unsaturated polyester [derived from poly(ethylene terephthalate) waste] and montmorillonite‐filled nanocomposites synthesized by in situ polymerization

Abstract

Postconsumer poly(ethylene terephthalate) waste bottles were glycolyzed as precursors of unsaturated polyester resin (UPR) and their montmorillonite (MMT)-filled nanocomposites. The glycolysis product (hydroxyl-terminated oligomers) was converted into UPR with various acid contents. These resins were miscible with styrene and could be cured with peroxide initiators to produce thermosetting unsaturated polyester (UP). Nanocomposites composed of UP matrix and organically modified clay were prepared by in situ polymerization. These were characterized for thermal and dynamic mechanical properties. Transmission electron microscopy was also used to study the morphology at different length scales and showed the nanocomposites to be compromised of a random dispersion of intercalated/exfoliated aggregates throughout the matrix. With an increase in unsaturated acid content (for a fixed content of clay), the value of storage modulus varied from 2737 to 4423 MPa. The glass-transition temperatures of these nanocomposites ranged from 54 to 78 C, and the crosslink density varied from 3.70 Â 10 5 to 5.72 Â 10 5 mol/m 3 . The X-ray diffraction (XRD) of modified MMT exhibited a peak that vanished completely in the polymer nanocomposites. Thus, the XRD results apparently indicated a distortion of the platy layers of nanofiller in the UP nanocomposites. The nanocomposites showed higher modulus values (2737-4423 MPa) compared to the pristine polymer (2693 MPa). From thermogravimetric analysis, all of the nanocomposites were stable up to 200 C and showed a two-stage degradation.

Processing, Properties, and Applications of Polymer Nanocomposites Based on Layer Silicates: A Review

“…Katoch and Kundu carried out the production of unsaturated polyester based on MMT nanocomposites by in situ polymerization. Poly(ethylene terephthalate) waste bottles were glycolyzed as precursors of polyester matrix.…”

Novel in situ synthesis in the preparation of ultraviolet‐curable nanocomposite barrier coatings

“…By using this in situ polymerization technique, exfoliated PET nanocomposites were produced with significant reductions in oxygen gas permeability. Katoch and Kundu29 have also reported the production of unsaturated polyester‐styrene based nanocomposites through an in situ type polymerization. By introducing the organoclay simultaneously with the monomers, nanocomposites with mixed intercalated/exfoliated morphologies were produced.…”

Unsaturated polyester nanocomposites based on poly(ethylene terephthalate) waste using different types of nanofillers

“…Katoch and Kundu 15 reported that T5 and T10 are generally used to evaluate the thermal stability of the bulk polymer, whereas T50 reflects the consistency of the cross-linked networks of the bulk polymer. It is evident that UP and all nanocomposite samples display one main step degradation between 400°C and 500°C, which can be attributed to the chain scission of polystyrene and polyester fragments.…”

“…In the field of polymer-based nanocomposites, a wide variety of materials are used as fillers, but much concern has been focused on layered silicates. [15][16][17][18][19][20] Among various thermoset resins, UPs are the most widely used matrix materials in polymeric composites. The major advantages of UP resins are a balance of mechanical, chemical, thermal, and electrical properties; low cost; and ease of handling and processing.…”