Fabrication and properties of polyethylene terephthalate (PET) aerogel composites from plastic bottle waste

To solve environmental problems of plastic waste, novel polyethylene terephthalate (PET) aerogel composites from recycled PET fibres of plastic bottles are developed successfully for the first time in this work. The PET honeycomb structures with various cell sizes are fabricated by layering and then bonding PET sheets with ethyl cyanoacrylate. The honeycomb cells are filled with the recycled PET fibres and a polyvinyl alcohol (PVA) crosslinker and then freeze-dried at -70 degrees C, 100 Pa for 48 h to obtain the PET aerogel composites (PACs). Effects of the various honeycomb cell sizes (1.0 - 2.0 cm), and PET-PVA ratios (5-1, 10-1, and 20-1), on the 3-dimensional (3D) mechanical and thermal properties of the PACs are investigated comprehensively. Due to the light-weight PET aerogel (PA) contribution, the PACs have the ultra-low densities of 0.042 - 0.072 g/cm3 and low thermal conductivities of 0.033 - 0.038 W/m center dot K. The honeycomb structure with the smallest cell size of 1.0 cm exhibits the highest compressive modulus of 15.30 MPa in the out-of-plane direction and 0.070 - 0.128 MPa in the other in-plane directions of the PAC. The compressive strength of the PACs in the out-of-plane direction is up to 730 times greater than those in the other in-plane directions and 2550 times greater than that of the PAs. The developed PACs perform better than aramid honeycomb-reinforced silica aerogel composites and common commercial products. They can be good alternatives for building insulation and cold chain applications.