The thermal response of a polymer composite material undergoing decomposition has been modeled. A one-dimensional transient thermal model with an nth order ap proximation for the rate of decomposition was applied. The model was tested by ex perimentally measuring the temperature profiles during decomposition for a glass- filled phenol-formaldehyde polymer composite. Additionally, the specific heat and thermal conductivity of the virgin and char components, heat of decomposition, and the kinetic parameters were experimentally determined and used as input to the model. The predicted temperature profiles are in good agreement with experimental temperatures obtained using a radiant heat flux apparatus.

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A new e llip soidal mirror re Aec to me te r is d esc rib ed, in whi c h radi a nt Au x from a n infrared mo noc hro lll a t (>I-is fo c use d on a specimen placed a t th e firs t foca l po int of th e ell ip so id a nd a th e rm o pil e d e tec tor is pla cet! at th e seco nd. Errors assoc iat ed with a n gul ar a nd a rea l variation s in se ns iti vity of th e det ector a nd wi th aberra ti o ns in th e opt ics we re largely e limin a te d thro ugh use of a s ma ll ave ragin g s ph e re pl aced ove r th e d e tector. Losses ca used by th e presc nce of th e e nt ra nee ho le in th c el lipsoidal m ir ror a nd frolll mirror abso rption we re e va lu a ted both th eoreti ca ll y a nd ex pe rim e nt a ll y. Co rrecti o ns for th ese losses pe rmitt ed abso lute re Acc ta nce to be o btain ed for bo th d iffu se and parti a ll y diffu se re Aec tin g s pecim e ns. In additi on, th e uniqu e op ti cs of th e e lli pso id a l mirro r provid e more ve rsa tilit y th an is ava il able in Ilrcv iou s re Hec to me te rs. Thi s ve rsa tilit y in c lu d es th e ab ilit y to acc ura te ly meas ure direc ti o na l-he mi s p he ri ca l, s pec ul ar, nons llec ular , and direc ti o na l-a nnul a r co ne re Aec tan ce. An a nal ys is of the acc uracy of th e in s trum e nt indi ca tes th a t an acc uracy of be tt e r th a n one pe r ce nt is poss ibl e fo r a ll e ng in ee rin g materia ls. Th e li se of th e s ulfur ave rag in g s ph e re a lso allowed the cons tru c ti o n of a s impl e acc u ra te s pec ul a r re Aec tome te r for ca li bration of th e mirror re fe re nce stand a rd s use d in th ese meas urement s.Key Words : Avera gin g sp heres, bidirect ional re fl ec t ali ce, diffu se re fl ec tance , e llipso ida l re Aee to me te r, infrared, infra re d det ec tors , re Hec tan ce . re Aee tollle te r, s pat ia l se ns itivit y, s pec tral refle c ta nce, spee ular re Aec tanc e.

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