Urethane polymers recycling

Urethane lacquers, 240 Urethane materials recycling of, 207-208 synthetic methods for, 246-258 Urethane oils, 202, 241 Urethane polymers, 197 Urethanes... 

Progress in Rubber and Plastics Technology 16, No.l, March 2000, p.61-8 CHEMICAL RECYCLING OF WASTE SATURATED POLYESTERS AND URETHANE POLYMERS TO YIELD RAW MATERIALS FOR THE PRODUCTION OF POLYURETHANES Kacperski M Spychaj T Szczecin,Polytechnic... 

CHEMICAL RECYCLING OE WASTE SATURATED POLYESTERS AND URETHANE POLYMERS TO YIELD RAW MATERIALS FOR THE PRODUCTION OF POLYURETHANES... 

Similarly, cells can be sealed temporarily with covers whenever they are opened. Cooling a cell to room temperature before opening also reduces the initial surge of vapor. A more elaborate measure was the replacement or modification of mercury pumps to provide sealless canned pumps. Along with the use of properly annealed piping and caulking with a urethane polymer to close any pinholes, this reduced emissions from the mercury recycle system. 

FVom the point of view of the application of ester, amide, and urethane polymers, hydrolysis, alcoholysis/glycolysis and ammonolysis/aminolysis reactions are the most important. These processes are often used for recycling to feedstocks and offer raw materials, mainly for virgin polymer/resin syntheses. The schemes of the respective reactions with brief comments on the practical importance of the particular processes are presented in Figures 2 to 4. A description of the important solvolytic degradation processes for ester, amide, and urethane polymers is also given in this chapter. 

The glycolysis of PUR products is the most important and popular method of chemical recycling [15,66]. This method is used both on a small scale (several tons per month) and on a very large scale (thousands of tons per year). In the urethane polymer chain fragments, most susceptible to glycolysis are the ester bonds. The urethane bonds are definitely less reactive, whereas the ether bonds are the least reactive [67]. 

Kacperski M and Spychaj T (1999) Chemical recycling of waste ester and urethane polymers as a source of raw materials for production of polyurethane, Polimery (Warsaw) 44 1-5 (in Polish). 

Product may be recycled when material is saturated with dissolved urethane polymers. 

Other tertiary recycling processes that have been developed include a Freeman Chemical Corp. process to convert PET bottles and film to aromatic polyols used for manufacture of urethane and isocyanurates. Glycolized PET, preferably from film, since it is often lower in cost than bottles, can be reacted with unsaturated dibasic acids or anhydrides to form unsaturated polyesters. These can then be used in applications such as glass-fiber-reinforced bath tubs, shower stalls, and boat huUs. United States companies that have been involved include Ashland Chemical, Alpha Corp., Ruco Polymer Corp., and Plexmar. Unsaturated polyesters have also been used in polymer concrete, where the very fast cure times facilitate repair of concrete structures. Basing polymer concrete materials, for repair or precast applications, on recycled PET reportedly leads to 5 to 10 percent cost savings and comparable properties to polymer concrete based on virgin materials. However, they are still approximately 10 times the cost of portland cement concrete. There appears to be little commercial application of these processes at present. 

Competitive penetration of polypropylene into other applications has primarily taken place in polyethylene, polystyrene, polyvinyl chloride (PVC), thermoplastic polyester, nylon-6 or -6/6, and sometimes directly from metals or thermoset polymers like phenolic or reinforced reaction injection molded (RIM) urethane. The reasons for market penetration by PP replacement vary widely with an assortment of material design options chemical resistance, heat resistance, recycleability, processability, economics, and aesthetics. 

In fact, RIM was the first plastic to be approved for bumper fascia in North America to meet the low-temperature crashworthiness demanded by some OEMs. Unfortunately, due to process complexity, RIM could not be fabricated at a high enough rate to meet the demands of large car platforms. Faster cycle time for part production is delimited by the speed of curing chemistry and the ability of the resin to flow into molds. Furthermore, the automotive industry wanted to move away from the use of thermoset polymer systems that cannot be remelted. This attribute of thermosets was labeled by the industry as non-recyclable, and the industry made room for other thermoplastics such as TPO that can be remelted. Reaction-injection-molded parts are made from urethane epoxies, polyesters, and polyamides. A study of cost versus performance reported that RIM gives the best cost-performance characteristic for composite materials and is competitive with steel. ... 

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