The first edition of this book had been written with the special aim to
provide the necessary information for an understanding of the
deformation and scission of chain molecules and its role in polymer
fracture. In this field there had been an intense ac- tivity in the
sixties and early seventies. The new results from spectroscopical (ESR,
IR) and fracture mechanics methods reported in the first edition had
complemented in a very successful way the conventional interpretations
of fracture behavior. The extremely friendly reception of this book by
the polymer community has shown that the subject was timely chosen and
that the treatment had satisfied a need. In view of the importance of a
molecular interpretation of fracture phenomena and of the continued
demand for this book which still is the only one of its kind, a second
edition has become necessary. The aims of the second edition will be
similar to those of the first: it will be at- tempted to reference and
evaluate completely the literature on stress-induced chain scission, now
up to 1985/86. References on other subjects such as morphology, vis-
coelasticity, plastiC deformation and fracture mechanics, where the
treatment was never meant to be exhaustive, have remained selective, but
they have been updated.