ABSTRACT:The solubility parameter value (SP value, ␦) is one of the most important factors in bonding technology. It was found that various kinds of rubber, such as VMQ (␦ Լ 7.3 cal 1/2 /cm 3/2 ) compounds, EPDM (␦ Լ 7.9 cal 1/2 /cm 3/2 ) compounds, and X-NBR (␦ Լ 9.3 cal 1/2 /cm 3/2 ), can bond to poly(oxy-2,6-dimethyl-1,4-phenylene) in their vulcanization process. This means that this bonding mechanism depends less on SP values. In this study, the bonding mechanism is hypothesized as an interfacial radical reaction, and the hypothesis is validated by molecular orbital (MO)

It has been found that poly(styrene-block-butadiene-block-styrene) (SBS) forms a regular structure and the structure transforms into another regular structure at the interface with poly(xylenyl ether) (PXE). This study examines the order-order transition phenomena with a transition electron microscopy (TEM) and an atomic force microscopy (AFM). According to TEM observations, the thickness of the morphological transition area depends on a temperature and time. In some cases, the thickness of the new regular structure's area could reach 1000 nm. Such phenomena have not been reported yet. A layer of which viscoelasticity changes continuously is observed at the interface of PXE and SBS with an atomic force microscopy (AFM), and the thickness of the layer is almost same as the thickness of the morphology transition layer observed with TEM.

Regarding a bonding between conventional PEBA and TPU, it has following difficulties : (a) The PEBA which has less soft segment, i.e. harder PEBA is difficult to bond with TPU directly by Insert molding. (b) Overmolding TPU onto the inserted PEBA can not get a good bonding. Overmolding PEBA onto inserted TPU should be applied for a good bonding. (c) The bonding strength strongly depends on the chemical structure of the soft segment of TPU.Daicel-Evonik Ltd. had prepared several kinds of PEBAs based on the concept of the bonding by interfacial reactions for the bonding test with TPU and it was confirmed the concept could solve these problems of conventional PEBA. Additionally it was found that PEBA specimen as an insert was not influenced by a storage time before TPU s overmolding, although TPU specimen lost its bonding performance by the time of the storage. This PEBA insert system was not available until Daicel-Evonik s new PEBA and PA12. It is expected that these advantages of DaicelEvonik s new PEBA and PA12 will be able to contribute to new fine design, cost saving and stable mass production.These new PEBA and PA12 also can bond with rubber based on K&K concept. Rubber + new PEBA + TPU three layer sheet is introduced as one of the examples of new application.

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