We have conducted Monte Carlo simulations to investigate two polar polymer models, modified from poly(vinylidene fluoride) (PVDF) to elucidate electric field induced chain elongation. We first treat the methylene and methylene fluoride groups of PVDF molecules as united atoms, similar to neutral alternating polyampholytes containing positive and negative charges. The second model is an all-atom model with explicit charges. In the weak coupling limit without intramolecular interactions, the conformational behavior of the two models agrees well at weak fields. However, the two models display pronounced deviation at strong fields, due to different local chemical structure between two models. (C) 2003 Elsevier B.V. All rights reserved.