Abstract: The invention relates to low baking temperature ultraviolet (UV) radiation curable or thermally curable powder coating polymer materials and compositions for heat-sensitive and/or flexible substrates. More specifically, such powder coating polymer materials and compositions are based on crystalline or semi-crystalline polymers but when subject to melting and flow-out at low temperatures (60° C.-140° C.) and upon curing in molten state by UV radiation or thermal energy, will give a (highly) flexible coating having either complete amorphous, non-crystalline, low glass transition temperature (Tg) polymeric matrix or low degree of crystallinity, low Tg polymeric matrix.