Waste Tetra Pak and Wood Shavings Composites: Flame Retardant Modification

This study aimed to achieve the value-added utilization of waste Tetra Pak (WTP) and to alleviate the shortage of wood resources by partially replacing wood shavings with WTP and using phenol-formaldehyde resin (PF) to prepare composites. Flame-retardant modification was conducted by introducing single additives-boric acid/borax (BA/Brx), ammonium polyphosphate (APP), and disodium octaborate tetrahydrate (DOT)-as well as the combined systems (BA/Brx/APP, BA/Brx/DOT, and BA/Brx/APP/DOT). Their effects on flame retardancy, mechanical properties, and thermal stability were investigated. It was found that all six systems improved flame retardancy, among which the DOT-modified composite specimen (Z3) achieved a limiting oxygen index (LOI) of 34.3%, representing a 25.6% increase compared with the control composite specimen (Z0), reaching the flame-retardant grade. The mechanical properties of Z3 met the requirements of GB/T 4897 (2015) for general particleboard. Fourier transform infrared spectroscopy (FTIR) indicated that the flame retardants interacted with the matrix through hydrogen bonding and functional composite specimen reactions. Thermogravimetric analysis (TG) showed that the char yield of Z3 reached 32.0%, which was 4.16 times higher than that of the control composite specimen, indicating a significant improvement in thermal stability. This study provides a feasible pathway for WTP recycling and the preparation of flame-retardant composites.