Optimization study of lignin oxypropylation in view of the preparation of polyurethane rigid foams

Contract grant sponsor: Portuguese Foundation for Science and Technology; contract grant number: SFRH/BD/ 18415/2004. Contract grant sponsor: French–Portuguese Scientific Cooperation Programme; contract grant number: F-13/06. Contract grant sponsor: European Commission (through a Marie Curie Intra-European Fellowship to W.T.); contract grant number: MEIF-CT-2005-025125.