6.4.3 Polyurethanes (PUs): 1C PU and 2C PU

PU adhesives are supplied as 1C and 2C systems that range in viscosity from self-levelling liquids to non-slumping pastes. They cure to form thermoset polymers with good solvent and chemical resistance. They are highly versatile and can vary in cured form from extremely soft elastomers to rigid, tough plastics. PUs offer a good blend of cohesive strength and flexibility, which makes them very tough, durable adhesives. They bond well to most unconditioned substrates, but may require solvent-based primers to achieve high bond strengths. They offer good toughness at low temperatures but typically degrade in strength after long-term exposure over 150°C (302°F). Since the cure of 1C moisture-curing PUs is dependent on moisture diffusing through the polymer, the maximum depth of cure that can be achieved in a reasonable time is limited to approximately 9.5 mm (0.38 in); 2C systems, on the other hand, offer an unlimited depth of cure.

Table of contents

Already have an account? Sign in

+33,000
professionals

have already
signed up

Award winning manual

Platinum Award for LOCTITE®X Digital Manual

The Digital Manual is for professionals by professionals

The manual is made entirely for you. However, if you’re still not convinced that free industry knowledge is for you, take a look at these user testimonials from the users of the manual.

"The topics are such that I can help take design related decisions very well at work. It's an interesting and knowledgeable read, I recommended my other colleagues to have a look at the manual as well."

Hanumant, Production Incharge

"The manual's chapters significantly enhanced my comprehension of various engineering topics. The manual adeptly presents explanations and examples of concepts, showcasing a high level of clarity and effectiveness in its content."

Tejas, Mechanical Engineer from a renowned Engineering College

"The release of this manual by a renowned brand such as Loctite has proven to be highly motivating for students. Its authentic content serves as a source of inspiration, encouraging students to engage actively in reading and learning."

Padmakar Deshmukh, Professor at an Engineering College