Abstract: Salts generally act as reinforcing compounds in polyurethane compositions. Salts containing a free-amine function generally increase the low-strain moduli more than salts which lack such free-amine functions or are neutral. The salts are generally formed by reacting a basic nitrogen function compound such as a monoamine or a diamine with a mono or a dicarboxylic acid.

Abstract: Urethane elastomers are produced by reacting a prepolymer with a chain extender or cure agent in the presence of limited amounts of water without adverse effects on the physical properties of the cured polyurethane.

Abstract: Urethane compositions generally free of phase separation patterns and flow lines are produced. One method includes the utilization of a nucleating compound which is generally added to a urethane prepolymer before any chain extension thereof. Examples of nucleating agents include urethanes, ureas and allophanates such as carboxylic acids, organic acid and anhydrides, amides, imides and the like. Another method includes adding a very small initial incremental amount of a curing agent to the prepolymer with an insoluble product being produced thereby and subsequently adding the remainder of the curing agent.

Abstract: A process and urethane composition for making urethane prepolymers from a polyisocyanate and blends of two or more urethane intermediates. The prepolymers so produced when cured have improved physical properties such as high low strain modulus and tensile strength relative to cured polyurethanes prepared from a mixture of prepolymers prepared by reacting a polyisocyanate with the component intermediates and subsequently blending the prepolymers.

Abstract: Urethane compositions are prepared which contain preformed adducts. The preformed adducts are prepared by reacting a polyisocyanate with various polyols or amine analogs thereof whereby a product insoluble in the urethane prepolymer is produced. An intermediate polyol is added to produce a prepolymer. The cured urethane compositions have high low-strain moduli.

Abstract: Urethane elastomers are produced by initially adding at least one incremental amount of a curing agent to a urethane prepolymer, having free polyisocyanate therein. Generally, free polyisocyanate-curing agent adducts are precipitated. Subsequently, the remaining amount of curing agent is added. Chain extension, accordingly, is favored which produces hard segment domains more evenly distributed in the polymer chain and imparts improved physical properties such as hardness, tear strength and high-low strain modulus.