(A) study on foam extrusion of thermoplastic elastomer vulcanizates using $CO_2$ as blowing agent

Abstract

Thermoplastic Elastomer Vulcanizates(TPEV) prepared by dynamic vulcanizing process, is a material which has both the properties of a thermosetting rubber (elasticity) and thermoplastics (processibility) . TPEV is cost effective for its good processibility and eco-friendly for its recyclability. For these reason, TPEV is rapidly and widely replacing vulcanized rubber such as NR, CR, EPDM, etc., and flexible PVC in various industrial regions. Recently, this requirement of replacement is expanded to foam area. But, several trials to developing TPEV foam could not show satisfied result. The processibility of TPEV is very poor because of its unique morphology and low melt strength. In this study, High melt strength TPEV/layered silicate nanocomposite(hereinafter HMS TPEV/layered silicate nanocomposite) was prepared by introducing of two new methods. The first is the introduction of nano-clay to TPEV system as nucleus for bubble formation as well as for bubble stabilization. The second is the introduction of high melt strength polypropylene(hereinafter HMSPP) to TPEV system to provide high melt strength during foaming processing. HMS TPEV/ layered silicate nanocomposite were prepared using 3 kinds of organic modified MMT (Montmorillonite) as nano-clay and 3 kinds of different mixing processes. Various evaluations such as degree of cross-linking, degree of filler dispersion (XRD and TEM), surface hardness and tensile properties were carried out for the HMS TPEV/layered silicate nanocomposites. As a result of TPEV/ layered silicate nanocomposite evaluation, Cloisite 15A and the specific process which using polypropylene/nano-clay master batch could give better mechanical properties and bigger d-spacing. TPEV/layered silicate nanocomposites can give more advantage of weight reduction which is a key issue in automotive industry because of fuel efficiency. The mechanical properties of TPEV/ layered silicate nanocomposite using small amount of MMT was similar to general TP...