SynopsisThe application of corresponding state principles to describe the properties of polymers is implicit in many of the fundamental studies of polymeric behavior. The seminal works of Prigogine, Hildebrand, Eyring, Flory, Gibhs, and DiMarzio in which multidimensional lattice representations and refined statistical mechanical approaches have been used are the basis for much of today's understanding of the thermodynamic behavior of polymers and their solutions. In this work the lattice energy of a polymer is defined in terms of reduced molecular parameters, and it is assumed that all polymers with the same functional form for their lattice energies will be in corresponding states. A reduced second order transition temperature is defined relative to a characteristic temperature T' = s~*/Zko*c, where the molecular parameters refer to the properties of the repeating segments of the polymer chain. Equations are derived that express the effects of molecular weight, plasticization, degree of crosslinking, and copolymerimtion on the second order (i.e., glass) transition temperature. In their limits, the equations are shown to reduce in form to equations derivable from free volume theory. They are also used to analyze succttssfully a variety of glass transition temperature data available in the Literature on homogeneous uncrosslinked and crosslinked polymers, plasticized polymers, and random copolymers.

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The glass transition temperature, dynamic shear moduli, and bulk viscosities of Phenoxy PKHH (a thermoplastic polymer made from bisphenol‐A and epichlorohydrin) filled with glass beads and Attapulgite clay were investigated. The glass temperature of the polymer increased with increasing filler concentration and with increasing specific surface area of the filler. The data were interpreted by assuming that interactions between filler particles and the polymer matrix reduce molecular mobility and flexibility of the polymer chains in the vicinity of the interfaces. From the measured moduli and the viscosities of the filled and unfilled materials, the modulus reinforcement ratio in the glassy state and the relative viscosity in the viscous state were obtained as functions of the filler type and concentration. The relative modulus for the glass bead composite system follows the Kerner equation, while the clay‐filled systems exhibit slightly greater reinforcement. The relative viscosities are strongly temperature dependent and do not follow conventional viscosity predictions for suspensions. It is suggested that the filler has a twofold effect on the viscosity of the composite materials; one is due to its mechanical presence and the other is due to modifications of part of the polymer matrix caused by interaction. Using the WLF equation to express all modifications of the matrix, one can isolate a purely mechanical contribution to the viscosity reinforcement. This mechanical part is approximately bounded by the theoretical predictions of Kerner,32 Mooney, 36 and Brodnyan,41 for suspension viscosities.

The thermomechanical stability of a number of organosilane surface treatments for glass fibers was evaluated for use in a fiber reinforced epoxy resin. All of the silane coatings were found to improve the tensile strength of E‐glass filaments, particularly at large gauge lengths. A phenylamino silane and an amino silane were particularly effective in this regard. The fiber/matrix interface was evaluated as a function of temperature and after exposure to boiling water using a single‐fiber composite test. All silane coatings transmitted a higher interfacial shear stress than obtained in composites with no coatings, and in all cases the shear stress transmission was considerably higher than would be expected from the yield properties of the resin. Measurements of the glass transition temperature of the epoxy resin, as well as Fourier‐Transform Infra‐Red analysis, indicated modification of resin properties in a zone around the glass fibers. Each of the silane coatings provided more stable thermomechanical properties than those obtained with uncoated glass, at least until the silanes were irreversibly degraded by boiling water. A phenylamino silane provided the most thermally stable properties. Finally, unidirectional E‐glass fiber reinforced laminae were fabricated and the measured values of longitudinal strength were compared favorably to theoretical predictions.

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The effects of the filler volume fraction and strength of adhesion on the mode of tensile failure of a particulate reinforced polypropylene (PP) are investigated using finite element simulation (FES). When there is perfect adhesion between constituents, an upper bound for tensile yield strength is found to be 1.33 times the matrix yield strength above a critical volume of particulate concentration. Utilizing Sjoerdsma's model for interacting stress concentration fields, one can determine the concentration dependence of the yield strength below the critical filler volume fraction. When there is no adhesion between constituents, a modified version of an equation by Nicolais and Narkis adequately describes a lower bound for the tensile yield strength. The particulate concentration and the matrix ductility are the prime factors in controlling the brittle failure of the composite. Upper and lower bounds for brittle failure strength are characterized using a strength‐of‐materials approach and stress concentration factors for both “perfect” and “zero” adhesion. The properties of calcium carbonate filled PP homopolymer were measured over a wide range of filler volume fractions. CaCO3 was either treated with stearic acid to prevent adhesion between constituents or used as received. Maleic anhydride grafted PP (MPP) was used to promote adhesion. For filler volume fractions below 0.2, yielding of the composite by combined microcavitation and shear deformation was the principal failure mechanism. At vf above 0.35, a brittle failure mechanism dominated. In the range between 0.2 and 0.35, both failure modes were observed in the populations tested. Good agreement was found between the experimental results and the proposed model.