Anelastic Deformation of a Thermoplastic-Matrix Fiber Composite at Elevated Temperature; Part I: Neat Resin Structure Characterization

Abstract

This is part of a series of articles on the properties of a thermoplastic polyamide matrix [PACM-12, DuPont, poly(bis-4-4'-dicyclohexylmethane) n -dodecanediamide]/graphite fiber (AS4, Hercules) composite. The structural characterization of the neat resin by differential scanning calorimetry (DSC) and X-ray diffraction as a function of processing history is described here. PACM-12, considered a representative thermoplastic matrix polymer for advanced composites, as well as an engineering plastic, is partially crystalline (ca. 20%) under normal composite processing conditions, but can be quenched to a completely amorphous state. The complex DSC results are shown to result, at least in part, from the presence of a different crystal structure in slow cooled PACM-12 than in quenched, annealed or fiber samples, to a melting-recrystallization-melting process during heating and to the effect of heating rate.

Elasto-Plastic Stress Analysis of Thermoplastic Matrix Composite Laminated Plates Under In-Plane Loading

“…For applications in advanced composite systems made up of polymericmatrix materials and high strength and stiffness reinforcements such as carbon fibers, thermosetting polymers have been utilized almost exclusively for several decades. However, several years ago, the introduction and development of new thermoplastic, e. g., Torlon, PEEK and Ryton, followed by numerous other candidates, as matrix materials in structural composites have given another dimension to the advanced application of reinforced plastic materials (Chen et al, 1993.). This new generation of engineering materials, thermoplastic polymer matrix continuous fiber composites, offer the potential of significant improvement and advantage in many aspects, compared with conventional reinforced thermosets (Hoggatt, 1973(Hoggatt, , 1975Hartness, 1980Hartness, , 1982Hartness, , 1984Rigby, 1982;Hergenrother et all., 1984;Muzzy and Kays, 1984).…”

Anelastic Deformation of a Thermoplastic-Matrix Fiber Composite at Elevated Temperature; Part II: Time-Temperature Dependent Matrix Behavior

“…HIS IS THE second in a series of articles [1][2][3][4][5][6][7] on the anelastic deformation behavior of a thermoplastic-polymer-matrix/graphite-fiber composite. In Part 1 [1] we reported the structural characterization of the neat resin; in this article the time and temperature dependent mechanical properties of the resin are addressed as a function of processing (structure) history.…”

“…In Part 1 [1] we reported the structural characterization of the neat resin; in this article the time and temperature dependent mechanical properties of the resin are addressed as a function of processing (structure) history. Such a study is needed for understanding matrix-dominated properties of the composite and to guide the improvement and application of the composite system as well as for understanding the role of processing on the properties of the plastic itself.…”

“…The polymer-fiber composite chosen for the study was poly(bis 4-4' dicyclohexylmethane) n-dodecanediamide (DuPont's PACM-12 [1])-AS4 (Hercules). This material processes readily [8], is expected to have characteristics and problems typical of high performance semi-crystalline polymer matrix composites in general, and was made available to us in appropriate amounts and forms by DuPont. Only limited studies of the PACM-121 resin and its composite have been reported in the literature [8][9][10][11][12][13].…”

“…In this article we report on the tensile deformation and failure behavior and on the dynamic-mechanical and creep properties of both injection-molded samples (shown in Reference [1] to be essentially amorphous) and a set of compression molded samples prepared with a range of processing thermal histories of importance in prepreg and composite fabrication. The creep behavior of the injection molded sample is expected to represent the upper bound of that exhibited by the polymer; increasing crystallinity would be expected to reduce the creep deformation, particularly at elevated temperatures.…”