The present invention relates to novel polymer compositions, particularly in the form of thermoplastic Vulcanisates, said compositions comprising the reaction product of a first polymer (rubber phase); a second polymer (thermoplastic phase); a carboxylic acid anhydride; either a vinylsilane in combination with a peroxide or a sulphursilane; and whereby said silane is allowed to react with the polymers first. The invention further provides for processes of manufacturing such compositions and for articles comprising such compositions.