Blends of natural rubber with speciality synthetic rubbers, such as Nitrile Rubber and Ethylene Propylene Rubbers have in the past failed to combine the best properties of polymers. This work contains the results of an ongoing research programme funded by the "Common Fund for Commodities" (CFC) where blending techniques have developed which enable high quality blends to be produced, optimizing the properties of two polymers. This development has reached the stage of field trials with products based on these blends. This book should be of interest to the rubber industry, rubber technologists, polymer technologists and professors, materials science specialists, graduate students, lecturers and teachers.