Thermal residual stresses in freely quenched semicrystalline polymer slabs were calculated based upon the modifications of the Indenbom theory for inorganic glasses and linear viscoelasticity. These modifications were introduced to include the influences of crystallization on mechanical and physical properties of the polymer during free quenching. The nonisothermal crystallization kinetic model due to Nakamura et al, was employed to calculate the variations of crystallinity. In the case of the Indenbom theory, a polymer during crystallization was assumed to undergo an abrupt transition from an ideal plastic state to an elastic state upon the completion of crystallization. In the case of linear viscoelasticity, the Morland-Lee constitutive equation was utilized with the effect of crystallization on the time-temperature dependent shear relaxation modulus taken into account. The Spencer-Gilmore P - V - T equation of state was employed to model the specific volume changes during crystallization and used to determine the local thermal loading that results from inhomogeneous densifications and gives rise to the thermal residual stresses in the slabs. Based on the above theoretical work, the thermoelastic and thermoviscoelastic models were developed, and the corresponding numerical simulation schemes were formulated to calculate the residual thermal stresses in freely quenched slabs of semicrystalline polymers, Free quenching experiments were carried out under various cooling conditions using isotactic polypropylene. The layer removal method due to Treuting and Read was utilized to measure the residual thermal stresses. The simulated and measured results were then compared. The effects of quenching conditions and crystallization on the development of residual thermal stresses were evaluated. It has been found that both coolant types and coolant temperature have significant effects on residual thermal stresses, In contrast, initial temperature of the polymer melt shows a slight influence only. (C) 2000 John Wiley & Sons, Inc.