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

Abstract

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., PFxRPFyw and PFxRPFywTOXz). Tensile strength (σf), impact strength (Is), and density (ρ) of PFxRPFyw and PFxRPFywTOXz specimens were reduced as RPF concentrations or average particle sizes increased. It is worth emphasizing that σf, Is, and ρ of each reaction‐injected PFxRPFywTOXz 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 σf and Is 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.

New Approach to Recycling of Epoxy Resins Using Nitric Acid: Regeneration of Decomposed Products through Hydrogenation

“…Unfortunately, this tends to result in a reduction in the mechanical strength of the recycled resin. Obtaining a recycled resin with adequate mechanical strength is therefore challenging, unless the pulverized resin possesses functional groups that can react with the virgin resin. , Many studies have therefore been conducted to pulverize CFRPs possessing rigid and strong carbon fibers to fill them into other resins − or concretes, , although the pulverized resin can be utilized only as a filler, thereby limiting its application. Moreover, the lengths of the carbon fibers and glass fibers contained in the composites are drastically shortened after pulverization, which results in a loss of the fiber value.…”