Polyurethane elastomer system
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...
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2021
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| Online Access: | http://www.osti.gov/servlets/purl/7305760 https://www.osti.gov/biblio/7305760 https://doi.org/10.2172/7305760 |
| Summary: | 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. |
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