Regeneration and utilization of waste phenolic formaldehyde resin: A performance investigation

Recycled thermosetting phenolic formaldehyde (RPF) resins were pulverized to micron‐sized powders and successfully reused as an effective component by reactive‐injecting with neat phenolic formaldehyde (PF) and/or trioxymethylene (TOX) to prepare regenerated phenolic formaldehyde (i.e., PF x RPF y w and PF x RPF y w TOX z ). Tensile strength (σ f ), impact strength (I s ), and density (ρ) of PF x RPF y w and PF x RPF y w TOX z specimens were reduced as RPF concentrations or average particle sizes increased. It is worth emphasizing that σ f , I s , and ρ of each reaction‐injected PF x RPF y w TOX z series having a fixed RPF concentration and average particle size improved to a maximum value, as TOX concentrations reached a corresponding optimal value. This is the first investigation to report that σ f and I s of proper regenerated PF/RPF/TOX specimens using ≦20 wt % RPF waste were ≥ 95% of those of the virgin reaction‐injected PF. Possible reasons accounting for these improved mechanical properties were proposed based on results from their Fourier transform infrared analysis (FTIR). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47445.