Reinforced-plastic charring

The industrial value of furfuryl alcohol is a consequence of its low viscosity, high reactivity, and the outstanding chemical, mechanical, and thermal properties of its polymers, corrosion resistance, nonburning, low smoke emission, and exceUent char formation. The reactivity profile of furfuryl alcohol and resins is such that final curing can take place at ambient temperature with strong acids or at elevated temperature with latent acids. Major markets for furfuryl alcohol resins include the production of cores and molds for casting metals, corrosion-resistant fiber-reinforced plastics (FRPs), binders for refractories and corrosion-resistant cements and mortars. 

As the organic plastic or its residual char are removed by the ablative aspects of the hyper-environment, the reinforcing fibers or particle fillers are left exposed and unsup-... 

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]. 

The forward bulkhead of the motor case is exposed to stagnant but hot gases, and thus must be lined with an insulative material. The modulus of this insulator is sufficiently low so as to transmit the chamber pressure into the external structural member. Insulators that are brittle tend to crack during the initial pressurization, with possible catastrophic burn-through of the motor case wall. Insulators are composed of an elastomer-modified charring resin (like a copolymer of butadiene-acrylonitrile and phenolic) with various reinforcements and/or low conductivity fillers. The bulkhead insulator is generally premolded in segments and then adhesively (plastic) bonded in place. 

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