How can you convince clients, consumers, students, or anyone that a polymer is a sustainable material? We have a strong association with polymers as being bad for the environment.  Single-figure Life Cycle Assessment (LCA) tools may be used to define sustainable materials, as they provide finite metrics that indicate the influence of material and material processing choices on a product’s environmental impact.  Generally, quantitative data like this is persuasive. Because this LCA data shows polymers to be sustainable materials, however, it may sound like science hokum, destined to be as derided and debated as global warming figures.  Because our gut response to the sustainability of polymers is so strongly negative, we need emotionally believable justifications for using polymers in products designed with sustainability in mind.  Kansei engineering studies have been developed to quantify peoples’ emotional responses to product features, including material choices. This paper documents the junctures where materials data from sustainability-focused Kansei engineering studies correspond with Okala LCA materials data to indicate sustainable polymer choices that people may be more likely to find convincing. Using both Kansei and LCA, polymers can be selected that satisfy sustainability-focused designers, clients and customers, leading to more effective sustainable products on the market.