Vahid Sendijarevic

Chemical recycling of mixed polyurethane foam stream recovered from shredder residue into polyurethane polyols

Recently, Troy Polymers, Inc. developed a chemical process for recycling of polyurethane foam scrap from shredder residue into polyols for polyurethanes (Sendijarevic, V. (2004). Process for Chemical Recycling of Polyurethane-containing Scrap, U.S. Patent No. 6,750,260 (assigned to Troy Polymers, Inc. and Polyventure, Inc.), June 15). This process is ideally suited for recycling polyurethane (PU) foam scrap from shredder residue (SR), which is a mixture of different types of PU foams based on different types of polyether and polyester polyols and different types of isocyanates, TDI and MDI. The PU foams separated from SR are contaminated with other types of cellular (foam) and fluff non-urethane materials. In stage one of this process, the PU foam is subjected to glycolysis, followed by filtration of the liquid glycolyzed product. In stage two, the glycolyzed products are used as initiators in reaction with propylene oxide to prepare novel PU polyols. A number of successful laboratory glycolyses have been carried out utilizing two different types of PU foams recovered from SR: (1) the best case scenario – handpicked PU foams from SR with > 80% conversion into liquid initiator and (2) the worst case scenario – mixed PU materials separated by an automated separation process from ELV shredder residue with 50% conversion into a liquid initiator. Both TDI-and PMDI-based flexible foams are prepared from the novel recycled polyols prepared by propoxylation of the glycolyzed products (initiators) obtained from the mixed PU materials. Preliminary economic analysis indicates that the commercial production of the polyols from the foam scrap can be cost effective.

Process monitoring and kinetics of rigid poly(urethane–isocyanurate) foams

Process temperature profiles of a two-component rigid poly(urethane–isocyanurate) foam system were studied and compared with the predictions of a one-dimensional numerical simulation. This model is based on experimentally determined thermophysical properties including thermal diffusivity, enthalpy of reaction, and rate of reaction. Temperature profiles were measured at three positions within the foam and at the foam surface for mold temperatures of 25°C and 55°C. A high rate of reaction and heat of reaction, along with low thermal diffusivity, cause temperatures near the foam center to be insensitive to mold temperatures for thick samples. Thermal analysis was used for determination of thermophysical properties. Temperature-dependent heat capacity, reaction kinetics, and heat of reaction were evaluated using temperature-scanning DSC. Thermal conductivity was analyzed from steady-state heat profiles. The system reaction kinetics indicated much faster kinetics than reflected by process cure temperature profiles made using thermocouples. The simulations accurately predict experimental results, allowing determination of demold time dependence on process conditions, including feed temperature, mold temperature programming, and sample thickness.

Novel Heat-Resistant Isocyanate- Based Polymers

This paper describes the preparation and properties of novel heat- resistant, isocyanate-based polymers. Poly(urethane-oxazolidones) (1/1 molar ratio) were prepared by reaction of NCO-terminated urethane prepolymers with polyepoxides. Poly(urethane-oxazolidone-isocyanurates) (3/3/1 molar ratio) were made by reaction of NCO-terminated urethane prepolymers with triglyci dyl isocyanurate. Poly(urethane-oxazolidone-isocyanurates) (3/3/2 molar ratio) were prepared by trimerization of equimolar mixtures of NCO-terminated urethane prepolymers and an NCO-terminated oxazolidone adduct. The poly(urethane-oxazolidone-isocyanurate) films exhibited very good stress-strain properties at room temperature (22°C), as well as at elevated temperature (150°C). The good thermal stability was also confirmed by TGA. These materials appear to be good candidates for heat-resistant elastomers, coatings, and adhesives. Poly(urethane-isocyanurates) (3/1 molar ratio) were also pre pared, and were compared with oxazolidone containing poly(urethane-iso cyanurates).

SCREENING STUDY TO EVALUATE SHREDDER RESIDUE MATERIALS

The Vehicle Recycling Partnership (VRP) initiated feasibility studies to evaluate the use of automated separation processes to recover plastics and polyurethane (PU) foams from shredder residue. One of the prevailing issues impeding the commercial success of these processes is contamination of the shredder materials. The contaminants include dirt, oils, glass, metal fines, polychlorinated biphenyls (PCBs) and heavy metals. The presence of PCBs and heavy metals was determined in a number of mixed plastics and PU foam samples separated using an automated separation process. An aqueous cleaning approach was investigated using various commercial surfactants to determine their effectiveness for removing oils, PCBs, and heavy metals. Mass balances of processed and cleaned materials were calculated to determine the cleaning efficiencies of the various surfactants.

Clear Nonionic Polyurethane Hydrogels for Biomedical Applications

Clear nonionic polyurethane hydrogels having a broad range of mechanical properties and degrees of swelling were prepared by both bulk (compression molding) and solution polymerization processes. Hydrogels con taining 70% water were also prepared which had an elongation of 1150% and a tensile strength of 280 kPa. The effects of the chemical structure, molecular weight, and functionality of polyether polyols and type of diisocyanate on hydrogel properties were studied. In addition, the type and concentration of crosslinker, and concentration of ethylene glycol, which was used as chain ex tender were investigated. In order to achieve transparency in the hydrogels, it was determined that poly(oxypropylene) glycols (PPGs) should be present in the system to disrupt the crystallinity of the poly(oxyethylene) glycol (PEG) soft segments. The PEG segments of the network which contain the hydrophilic moiety are responsible for the absorption of water. However, in addition to the concentration of oxyethylene, the degree of swelling of the hydrogels was also determined by measuring the elasticity of the polymer network. The elasticity of the polymer network is determined by the molecular weight between cross links (crosslink density) and the concentration of hard segments in the net work. The concentration of hard segments was controlled by the concentration of chain extender. The crosslink density was controlled by the diol/triol ratio and the respective molecular weight of each component.

New Heat Resistant Isocyanate Based Foams for Structural Applications

This paper describes unique types of isotropic urethane-isocyanurate and urethane-urea isocyanurate foams based on a combination of an aromatic polyester polyol and an amine-containing tetrol as the only polyols with a low functionality polymeric isocyanate

Utilization of Polyurethane Foam Scrap as a Sole Binder for Recycling of Automotive Interior Trim Products

A number of rear-seat-to-back-window trim panels (CHMSL covers) were manufactured by thermoforming ground polyurethane-cored headliner (UROCOR) scrap with PMDI as a binder with and without water as a component of the composite mixture utilizing industrial equipment at a Lear plant in Holland, Michigan. Unexpectedly, it was found that UROCOR scrap which contains a significant amount of flexible and semi-rigid polyurethane foam can be thermoformed without addition of PMDI. In order to confirm that the polyurethane scrap can be used as a binder, the polyurethane seating foam scrap was successfully recycled as the sole scrap and in 75/25 and 50/50 mixtures with resinated fibers.

Solidification/Stabilization of Hazardous Wastes by Means of Polymeric Isocyanate-Based Binder Systems:

Described refinements in RIM recycling technology include progress in pulverization efficiency and the effect of particle size, particle distribution, moisture content, and paint on molding and performance. Alternative approaches and approximate costs to configure RIM machines for three stream processing are discussed, as are the current state-of-art techniques of &dquo;hot compression molding&dquo; of RIM granulate. The incorporation of pulverized, vinyl clad low density RRIM scrap into virgin liquid raw materials, and the use of this blend to mold vinyl covered interior door panels, has been accomplished using commercial, conventional twostream RIM equipment. This demonstration, which avoids the need to first separate the coverstock material, expands the utility of RIM recyclate into the developing application of light weight covered interior automotive substrates. The use of regrind in this LD-RRIM process is described.

Technical Session XX: Chemical New Heat Resistant Isocyanate Based Foams for Structural Applications

formance to RIM moldings, the conventional glass fibers affect the surface quality of moldings causing declined DOI (distinction of image) due to the surface roughness remaining even after coating. Needless to say the shorter the fiber length is, the better the surface quality is. However, shorter fillers must be added in larger amounts to give comparable stiffness to moldings since the reinforcement efficiency depends mostly on aspect ratio. So, shorter fillers are not always the best solution. In consideration of the situation, we have carried out the study on Bayflex 110 RIM systems with various new and well known fillers such as milled glass fibers with different diameters, sieved processed mineral fibers and inorganic whiskers to find a filler giving both enough reinforcement and excellent DOI. We found that length and diameter of fillers affect surface roughness of molding very much and that fibers giving outstanding surface quality as well as sufficient reinforcement have fiber length under eighty microns and diameter under five microns. Fillers with these dimensions have been successfully applied to RRIM exterior parts in the industries.