Recycling of rigid polyurethane foam: Micro‐milled powder used as active filler in polyurethane adhesives

Abstract

Rigid polyurethane (PUR) foams are widely used as heat insulation material in construction industry or for electronic appliances manufacturing. After finishing their lifetime it is necessary to eliminate foam wastes. The aim of this study was to prepare a pair of industrial polyurethane adhesives of medium viscosity containing recycled rigid polyurethane foam. Three methods of milling were tested: knife-milling, two-roll milling and ball-milling. Only two-roll milling gives the PUR micro-powder usable for following adhesives modification. The micro-powder was used as passive filler in polyurethane adhesives and potential reactivity for polyol pack replacement was studied. Hydroxyl and amine numbers were determined in mixture with virgin polyol. One-component polyurethane prepolymer adhesive was prepared using various dosages of the micro powder and the tensile strength of bound wood was measured. As additional parameters also free film adhesive mechanical parameters were tested and particle size distribution of the micro powder was analysed. Two adhesive formulations were prepared for independent evaluation of the micro

Properties of Rigid Polyurethane Foam Filled with Sawdust from Primary Wood Processing

“…The increase in viscosity of PUR systems under the influence of the filler is also considered to be the main reason for the increase in these times, which consequently limits proper cell expansion. On the basis of studies conducted so far, it can be concluded that with the increase in the number of various types of fillers introduced into the microstructure of foams, higher viscosity of PUR systems and an increase in their processing times are observed [ 12 , 15 , 31 , 42 , 44 , 45 , 46 , 47 , 48 , 49 ]. Furthermore, the functional groups of fillers can react with isocyanate groups, which can affect the proper stoichiometry of the reaction and limit the release of blowing agents (CO 2 ) [ 15 , 44 , 50 ].…”

Computational Study of Catalytic Urethane Formation

“…A varied set of nitrogen-containing catalysts have been selected from the literature [ 9 , 26 , 27 , 28 , 29 , 30 , 31 ]. Based on their applications, the catalysts can be divided into four groups as follows: 1, 2–4, 5–7, and 8, which are used in the synthesis of flexible, rigid, and semi-rigid foams, and others, respectively ( Figure 1 and Table 2 ).…”

Sustainable Polyurethane Networks Based on Rosin with Reprocessing Performance

“…However, it is exceptionally difficult to recycle the covalently cross-linked networks of PU thermosets. Though mechanically grinding approaches have been employed to downcycle PU thermosets into fillers to enhance adhesive composites [3], chemical recycling of PU thermosets remains a challenge.…”