Geoffrey Allen was a chemist known for his work on the physics and chemistry of polymers, and in particular, the thermodynamics of rubber elasticity — what puts the bounce into rubber. He was amongst the first researchers to measure cohesive energy densities of intermolecular forces in polymers. He also did pioneering work on miscibility — a property of substances that mix together.
As a consequence of ICI funding, Geoffrey formed a joint research laboratory at the University of Manchester, where he was Professor of Chemical Physics. He later became part-time Assistant Director of the ICI Corporate Research Lab at Runcorn. In 1981, he moved fully into the private sector becoming Research and Engineering Director at Unilever.