Ablators plastic-base

Syntactic materials based on polybenzimidazole and glass or phenolic microspheres (y = 40-500 kg/m3) have been described in the literature109 nl). They have been used as ablation materials that consist of two layers, one of which is a monolithic carbon plastic. Carbon fiber was added to the polyimide binder to improve the mechanical properties of the material. 

Elastomers Another major class of plastic ablators is elastomeric-base materials and particularly sihcones. During ablation, they thermally decompose by such processes as depolymerization, pyrolysis, and vaporization. The silicone elastomers provide low thermal conductivity, high thermal efficiency at low to moderate heat fluxes, low temperature properties, elongation of several hundred percent at failure, oxidative resistance, low density, and compatibility with other structural substrate materials. Elastomeric materials are generally limited by the amount or structural quality of the char formed during ablation, which restricts their use to hyperthermal environments of relatively low mechanical forces. 

Since surface roughness is crucial for adhesive strength of the metallization subsequently appiied, the polymer matrix is modified by suitable, radiation-resistant fillers (mostly inorganic). The fillers in the plastic are not ablated by the laser. This produces microscopicaily small caverns and back-cuts in which the copper can anchor itself firmiy, so the metallization acquires a secure key to the base material without compiicated post-treatment (Fig. 2.16) [73, 75,172],... 

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