One of Keller's most important accomplishments stemmed from his 1957 hypothesis that polymer crystals were formed by long molecules more or less regularly folding back on themselves ("chain folding"). This significant departure from earlier conceptions accounted for the type of thin plate- like and well-shaped crystals observed using the then new technique of electron microscopy.
His early classic work was on polyethylene - often denoted "polythene" in Britain - and was later extended to other crystallisable polymers at Bristol, as well as by other workers in Europe, Japan and North America.
As is often the case with quantum leaps elsewhere in science, these developments did not take place unopposed. Keller was a master at devising insightful experiments to test his hypotheses, and in time workers in the field came to see the worth and potential of his ideas and to themselves employ and advance them. Meanwhile the chain folding concept turned out to be helpful in understanding the physical and chemical properties of crystallisable polymers; these are matters of practical as well as scientific importance. Thus Keller set aside the old mould, though allowing consideration of it, and advanced a new and more vital one to the enrichment of science and technology.
He was born Andras Keller in Budapest in 1925. His scientific education began in 1943 when he entered the University of Budapest, earning his BSc in chemistry cum laude in 1947. He began his PhD studies at the same university but his path to world recognition in the field of polymer science was interrupted by the rapidly deteriorating political situation in Hungary in 1948, which caused him to abruptly depart that country.
It was arranged for him to take a position with Imperial Chemical Industries Ltd (ICI) in Manchester, as technical officer in the Polymers Division. In this new atmosphere he became aware of problems in polymer science and technology that aroused his curiosity and led him to examine aspects of polymer crystallisation: it was in this area that he and his colleagues and students laboured and in time created a revolution.
He became a naturalised citizen of the UK in 1954. When he left Hungary, he had finished his PhD thesis, but had not taken the final oral examination required for a diploma. This was rectified by his next move. In 1955 he removed to the Bristol University Physics Department as Research Assistant heading a team financed by the Ministry of Supply (later Ministry of Aviation). At Bristol he began to further develop his ideas on crystallisation, and obtained his PhD there in 1958. With the encouragement of the head of the Physics Department, Professor F.C. (later Sir Charles) Frank, Keller stayed on at Bristol, being appointed Lecturer in Physics in 1963, Reader in 1965, and Research Professor in Polymer Science in 1969. He retired from the latter position in 1991, but remained fully active in research until his death.
Keller was the recipient of many awards and honours. He was elected Fellow of the Royal Society in 1972 and a member of Academia Europaea in 1994. Other recognition included the High Polymer Physics Prize of the American Physical Society, the Swinburn Medal of the Plastics and Rubber Institute and the Max Born Medal of Physics (jointly awarded by the Institute of Physics and the German Physical Society).
Andrew Keller had another side. He was an able linguist, and enjoyed mountain walking, swimming, skiing, travel, opera and concerts.
A special conference on crystallisation of polymers will be held in his memory as part of the meeting of the American Chemical Society this August in New Orleans.
Andras (Andrew) Keller, polymer scientist: born Budapest 22 August 1925; Research Assistant, Department of Physics, Bristol University 1957-63, Lecturer 1963-65, Reader 1965-69, Research Professor in Polymer Science 1969-91 (Emeritus); FRS 1972; married 1951 Eva Bulhack (died 1997; one son, one daughter); died 7 February 1999.