What is the difference between aromatic and aliphatic urethanes?
Aromatics are one of the more common chemistries in the world of casting urethanes. They tend to be more economical to produce, have good physical properties, and range from low durometer elastomers to rigid plastics. Their downsides tend to be poor UV resistance and lower chemical resistance. The Aliphatic urethanes have outstanding UV stability, color stability, and chemical resistance. Their down side tends to be longer gel and demold times, low heat distortion, low tolerance to colder casting temperatures, and higher material costs. Blends of Aliphatic and Aromatic urethanes can exhibit excellent UV resistance, good heat distortion, and good physical properties.
