Thermoset recyclate composites

Table 5.5 Mechanical properties of PP-thermoset recyclate composites at 23 °C ...

Table 1 Mechanical properties of polypropylene/thermoset recyclate composites (at 23T).

Details are given of the development of energy and material recycling processes for thermosetting polymer composites. Applications in the cement industry and in coal fired fluidised bed combustion plants are discussed. 3 refs. 

Thermosensitive hydrogels, 13 743 THERMOSET Thermoset recycling pyramid, 13 780-781 Thermoset elastomers, 20 71 Thermoset epoxy resins, curing of, 10 421 Thermoset flexible polyurethane foams properties of, 25 461 Thermoset matrix composites, 21 456 Thermo set molding properties of diallyl isophthalate, 2 262t Thermoset polymers, 25 455 cured, 10 425... 

The recycling of wastes is difficult for thermosets and composites because of the cross-linking and/or the presence of fibres broken during recycling. 

Research on the pyrolysis of thermoset plastics is less common than thermoplastic pyrolysis research. Thermosets are most often used in composite materials which contain many different components, mainly fibre reinforcement, fillers and the thermoset or polymer, which is the matrix or continuous phase. There has been interest in the application of the technology of pyrolysis to recycle composite plastics [25, 26]. Product yields of gas, oil/wax and char are complicated and misleading because of the wide variety of formulations used in the production of the composite. For example, a high amount of filler and fibre reinforcement results in a high solid residue and inevitably a reduced gas and oiFwax yield. Similarly, in many cases, the polymeric resin is a mixture of different thermosets and thermoplastics and for real-world samples, the formulation is proprietary information. Table 11.4 shows the product yield for the pyrolysis of polyurethane, polyester, polyamide and polycarbonate in a fluidized-bed pyrolysis reactor [9]. 

Other materials in waste that is thermally processed also were studied by pyrolytic techniques, typically with the purpose of regenerating the monomers or of obtaining other useful small molecules. For example, pyrolytic studies were performed for the evaluation of the possibilities for re-utilization of nylon carpet waste [7], the recycling of thermoset polymeric composites [8], the recovery of methyl methacrylate from poly(methyl methacrylate) waste [9], as well as for other raw material recovery from pyrolysis of plastic waste [10]. The results of incineration of various other types of waste also were studied at model scale [11, 12). These studies were applied to specific waste materials associated with the manufacturing process or to municipal solid waste [13-15)... 

Examples of filled polymer compositions are discussed, where the role of the preparation method has been clearly identified in relation to compound structure and end properties. Particular attention is also given to recent developments in the field of natural fibre-filled composites, supercritical fluid assisted processing of filled polymers, re-use of thermoset recyclate fillers and silicate layer polymer nanocomposites. 

Processes that do not rely on the melting of plastic recyclate relate to large scale predominantly tertiary and quaternary recycling. Thermoset matrix composites recycling also falls within this description, and the principal recycling routes for thermoset matrix composites are outlined below. 

The primary UPR end markets are construction, automotive, and marine industries widi applications such as house paneling, tub and shower applications, chemical-resistant storage tanks, pultruded profiles, and fiberglass composite boat hulls. The UPR industry is mature, with a world production close to 1.7 million tons (Table 2.2), but must face two important issues increasingly strict regulations for styrene emissions and poor recycling potential for polyester thermosets.48 49... 

London, BPF, 1994, p.59-64. 627 STRATEGIES FOR RECYCLING AND ENERGY RECOVERY FROM THERMOSET COMPOSITES... 

Recycling of glass fibre-reinforced plastics is reviewed, with special emphasis on remelting of thermoplastic composites, mechanical recycling of thermoset composites, depolymerisation and dissolution of thermosets and thermoplastics, closed loop recycling of glass, and the use of glass as a mechanical compatibiliser. 32 refs. 

The updated situation of Recycling Thermoset Composites in Japan is diseussed. The dismantling or cutting up of ships, baths, water tanks, and automotive parts are eovered. Recyeling methods include pyrolysis and incineration. Details are also given of uses for recycled materials such as automotive parts, building materials and cement additives. 18 refs. 

Thermoset plastics have also been pyrolysed with a view to obtain chemicals for recycling into the petrochemical industry. Pyrolysis of a polyester/styrene copolymer resin composite produced a wax which consisted of 96 wt% of phthalic anhydride and an oil composed of 26 wt% styrene. The phthalic anhydride is used as a modifying agent in polyester resin manufacture and can also be used as a cross-linking agent for epoxy resins. Phthalic anhydride is a characteristic early degradation product of unsaturated thermoset polyesters derived from orf/io-phthalic acid [56, 57]. Kaminsky et al. [9] investigated the pyrolysis of polyester at 768°C in a fiuidized-bed reactor and reported 18.1 wt% conversion to benzene. 

In 1990, the JRPS organized a tertiary committee, the RP Recycling and Treatment Council (RTC) for the solution of technological and social problems regarding recycling thermoset composites waste. 

The result of discussion for development of Recycling Thermoset Composites by the RTC and the other organizations concerned in Japan from 1991 to 1993 lead us to the following policies to take. 

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