Moisture cured, one component, reactive polyurethane (PU) adhesives are formulated using an isocyanate and amorphous and crystalline polyols of varying composition which are reacted to form a polyurethane prepolymers. These prepolymers can be liquid or they can be solid at room temperature. If they are solid at room temperature, they are considered reactive hot melt adhesives. All reactive PU adhesives contain residual isocyanate functionality that is reactive with moisture that comes from the atmosphere and/or the surface to be bonded. Reactive PU adhesives contain catalysts to promote the moisture cure and also contain other additives to control rheology, open time and strength of the resulting polyurethane polymer. The choice of polyols, based on performance requirements is an important factor in formulating any polyurethane system. Designing reactive, one component adhesives is no different. Understanding how isocyanate and polyol structure affect reactivity and the physical properties of the formulated adhesive is an important aspect of formulation, which this webinar is intended to provide. The presentation includes: An introduction to adhesive considerations, Comparison of PUR adhesive systems, the chemistry of isocyanates and polyols, Formulating from a Structure / Property perspective, Summary of important concepts