Polyurethane elastomer system

• Main Author: Creed, K.E.
• Language: unknown
• Published: 2021
• Subjects: 36 MATERIALS SCIENCE; URETHANE; CROSS-LINKING; SHEAR PROPERTIES; CHEMICAL REACTIONS; STOICHIOMETRY; TENSILE PROPERTIES; CARBAMATES; CARBONIC ACID DERIVATIVES; CARBOXYLIC ACID SALTS; MECHANICAL PROPERTIES; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; POLYMERIZATION; Carbonic acid
• Online Access: http://www.osti.gov/servlets/purl/7305760; https://www.osti.gov/biblio/7305760; https://doi.org/10.2172/7305760

The OSHA restrictions on the use of 4,4'-methylenebis (2-chloroaniline) for curing urethanes resulted in the use of a recently developed system based on a mixed aliphatic/aromatic polyol curative. However, continued evaluation of this system evidenced substantial lot-to-lot and inter-laboratory variations in shear modulus data. This was initially attributed to moisture pickup and/or aging but further tests indicated a stoichiometry problem. Normally with an amine cured urethane, the amount of curative used is only 95 percent of that required to react with all of the isocyanate groups (0.95 to 1 ratio). Shear modulus data indicated that for the polyol system, a 1 to 1 OH/NCO ratio was needed to provide consistent properties. Since previous test data had not evidenced this variability, a program was initiated to assess the stoichiometric effects in greater detail. In addition to the polyol curative evaluation, six urethane systems that do not contain 4,4'-methylenebis (2-chloroaniline) were assessed for tensile strength, elongation and tear strength.