Innovative TPV two-phase polymers: formulation, morphology formation, property profiles and processing characteristics

An innovative TPV [TPV: thermoplastic vulcanizates characterized by a two-phase morphology with continuous polypropylene matrix and synthetic rubber phase in a microdisperse distribution and highly crosslinked state.] two-phase polymeric system is described. The new TPV is composed of a polypropylene (PP) matrix in which a metallocene-type ethylene/octene copolymer (EO) is dispersed. The EO-copolymers are grafted with vinyl organosilanes, then blended with PP, hydrolyzed and water-crosslinked in a co-rotating, intermeshing twin-screw extruder. The resulting TPV-grades are easy to process into articles showing an attractive range of properties. The advantages are due to blend composition and crosslinking concept. The new TPV's can be-processed without pre-drying. Moldings are characterized by excellent surface quality and absence of odor as a result of the innovative use of the EO elastomer and the modified crosslinking concept. They can easily be colored to any desirable-shade. The reduced cost of ingredients is another advantage of the newly developed thermoplastic elastomers. High ultimate strength ( sigma sub R ) and elongation-at-break ( epsilon sub R ) values and a broad spectrum of different Shore A grades open up many new fields of application. The main focus has been on the automotive applications not least because of very low fogging rates.