Flexible polyurethane foams synthesized employing recovered polyols from glycolysis: Physical and structural properties

Abstract

Polyurethane (PU) is one of the most important polymers with a global production of 17.565 million tons, which makes its recycling an urgent task. Besides, the main goal of PU recycling is to recover constituent polyol as a valuable raw material that allows to obtain new PU with suitable properties. Split‐phase glycolysis can be considered the most interesting PU recycling process since provides high‐quality recovered products in terms of polyol purity. The aim of this work was to evaluate several recovered polyols as replacement of the raw flexible polyether polyol in the synthesis of new flexible PU foams. These recovered polyols come from the split‐phase glycolysis of different types of PU foams and employing as cleavage agents diethylene glycol or crude glycerol (biodiesel byproduct). The influence of the foam waste type and of the cleavage agent on the foams properties was analyzed. The recovered polyols were evaluated by performing several foaming tests according to the method of free expansion foaming of conventional flexible foam. Synthesized flexible foams containing different proportions of recovered polyols were characterized by means of scanning electron microscopy, density and tensile properties; obtaining similar and sometimes even better values compared to the foams manufactured from commercial polyols. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45087.

Recycling of Flexible Polyurethane Foam by Split‐Phase Alcoholysis: Identification of Additives and Alcoholyzing Agents to Reach Higher Efficiencies

“…As a benchmark, the alcoholysis of the TDI‐based flexible PU foam was first performed in diethylene glycol, by applying a glycol to PU foam weight ratio of 1.5:1, with a Bi III neodecanoate catalyst, as a non‐toxic alternative to tin compounds employed in the state‐of‐the‐art alcoholysis . Bismuth compounds have been reported as very active catalysts in an alcoholysis model reaction; also in our preliminary experiments Bi III neodecanoate stood out as a particularly active catalyst (Table S3 in the Supporting Information) .…”

“…The main goal of split‐phase alcoholysis is to recycle the polyether polyol from end‐of‐life polyurethanes for the production of new flexible foams. In that respect, the polyether polyols should meet several quality specifications: an average molecular weight between 2000 and 6000 g mol −1 , a functionality of 2 to 3 and a hydroxyl number between 28 and 100 mg KOH g −1 . The latter range is still fairly wide, and closer emulation of the original OH value would allow the polyol to be reintegrated in the process with minimal protocol adjustments.…”

“…The polyether polyol obtainedb yl arger scale split-phase alcoholysis in diglycerol,w ith 2-pyrrolidone as alcoholysis accelerator,a nd by subsequent purification (Table 4) was used to prepare new TDI-basedf lexible PU foams.T ot hat end, the recycled polyether polyolw as mixed with virgin polyether polyol in various proportions, ranging from 0% to 60 % of the recycled polyether polyol ( Table 5). Hydroxyl value [b] [mg KOH g À1 ] Amine value [b] [mg KOH g À1 ] after alcoholysis 97 98 0.0 0.2 1.6 0.1 1.5 69 (80) 16 (27) after purification 99 -0.0 0.3 0.5 0.4 0.0 58 (61) 5 ( 10) [a] Alcoholysis conditions: PU foam (400 g), diglycerol (0.5:1 PU), 2-pyrrolidone( 0.1:1 PU), BK850 catalyst( 0.01:1 PU), 200 8C, 300 min of depolymerization. Purification conditions: upper phase (254 g), diglycerol (1:1 UP), 150 8C, 30 min of washing.…”

Glycolysis of Polyurethanes Composites Containing Nanosilica

“…The characteristics of this upper phase or recovered polyol are like those of other recovered polyols and allow foreseeing a good result when foaming it, although adjusting the isocyanate index due to the increase of hydroxyl groups [ 28 ].…”

Enhancement of the Tensile and the Compression Properties for Heat- Cured Acrylic Resin Denture Base Materials

“…When the yield point is exceeded in compression, a permanent deformation or compression set occurs. This compression set is important in characterizing the behavior of flexible foams (25) .…”