AbstractExcessive distortion, warpage, and sagging resulting from heat generation by electrical components and transporting environments has limited the penetration of PVC into high flow injection molding applications such as business machine, appliance, and electrical housings. High flow PVC formulations lose their rigidity at temperatures typical of these applications because the application temperatures are very close to the glass transition temperature (Tg) of PVC. In addition, thermal stresses built in during processing relax near theTgof the material. Adding a glutarimide acrylic copolymer increases theTgof PVC; consequently, raising the temperature at which the PVC/glutarimide copolymer blend loses its rigidity well above required application temperatures. This paper describes the effect of adding a glutarimide copolymer on the heat distortion properties and other physical and rheological properties important to high flow injection molding applications.