Abstract: A joint boot molded from an acrylic rubber/polyamide-based thermoplastic elastomer, which comprises a polyamide resin and a cross-linked acrylic rubber. The acrylic rubber/polyamide-based thermoplastic elastomer is a dispersion of the rubber in the polyamide resin, obtained by dynamic cross-linking of the acrylic rubber, preferably by covalent bond-linkable cross-linking of the polyamide resin with the acrylic rubber. The joint boot has a fully satisfactory heat resistance required even for use at the inboard side.

Abstract: A thermoplastic elastomer blend, which comprises 15 to 85% by weight of a cross-linked acrylic rubber-dispersed polyamide-based thermoplastic elastomer, and 85 to 15% by weight of a polyester-based thermoplastic elastomer, or which comprises 20 to 90% by weight of a cross-linked acrylic rubber-dispersed polyamide-based thermoplastic elastomer, and 80 to 10% by weight of a polyamide-based thermoplastic elastomer. The cross-linked acrylic rubber-dispersed polyamide-based thermoplastic elastomer is used also as a blend with both of the polyester-based thermoplastic elastomer and the polyamide-based thermoplastic elastomer. The thermoplastic elastomer blend is effectively used as joint boot-molding material, etc., having distinguished heat resistance and low temperature characteristics, applicable also to the joint boot inboard side.

Abstract: A fluorine-based magnetic fluid, which comprises (A) fine magnetic particles as dispersed in (D) a perfluoropolyether base oil represented by the following general formula:F?CF(CF.sub.3)CF.sub.2 O!mRfwhere Rf is a perfluoroalkyl group by means of general formulae:(B.sub.1){F?CF(CF.sub.3)CF.sub.2 O!nCF(CF.sub.2) (Y)v(R)wO}tPO(OM)u,(B.sub.2)F?CF(CF.sub.3)CF.sub.2 O!nCF(CF.sub.3)YRSO.sub.2 Mor(B.sub.3)F?CF(CF.sub.3)CF.sub.2 O!nCF(CF.sub.3)X(RO)sCH.sub.2 COOMwhere R is a divalent organic group; Y is a COO group or CONH group; X is a COO group or CH.sub.2 O group; and M is a hydrogen group, an alkali metal, an alkaline earth metal or an ammonium group and perfluoroether carboxylic acid amide compounds represented by the following general formulae:(C.sub.1)F?CF(CF.sub.3)CF.sub.2 O!pCF(CF.sub.3)CONH(CH.sub.2)qNH.sub.2,(C.sub.2)F?CF(CF.sub.3)CF.sub.2 O!pCF(CF.sub.3)CONH(CH.sub.2 CH.sub.2 NH)rHor(C.sub.3)F?CF(CF.sub.3)CF.sub.2 O!pCF(CF.sub.3)CONH(CH.sub.2 CH.sub.2 NH)rCOCF(CF.sub.3)?OCF.sub.2 CF(CF.sub.

Abstract: A fluorine-based magnetic fluid, which comprises (A) fine magnetic particles dispersed in (D) a perfluoropolyether base oil represented by the following general formula:F(CF(CF.sub.3)CF.sub.2 O).sub.m Rfwhere Rf is a perfluoroalkyl group, by means of (B) a perfluoroether carboxylic acid or salt thereof represented by the following general formula:F(CF(CF.sub.3)CF.sub.2 O).sub.n CF(CF.sub.3)COOMwhere M is a hydrogen atom, an alkali metal or an ammonium group, and (C) a perfluoroether compound represented by the following general formula:F(CF(CF.sub.3)CF.sub.2 O).sub.p CF(CF.sub.3)X(RO).sub.q CH.sub.2 COOM',F(CF(CF.sub.3)CF.sub.2 O).sub.p CF(CF.sub.3)(Y).sub.r R'OSO.sub.3 M' or(F(CF(CF.sub.3)CF.sub.2 O).sub.p CF(CF.sub.3)(Y).sub.v (R).sub.w O).sub.t PO(OM').sub.u.Fluorine-based magnetic fluid has a high affinity of the fine magnetic particles toward the perfluoropolyether base oil and is effectively used as a sealing material for vacuum apparatus.

Abstract: A fluorine-based magnetic fluid, which comprises (A) fine magnetic particles as dispersed in (D) a perfluoropolyether base oil represented by the following general formula:F?CF(CF.sub.3)CF.sub.2 O!mRfwhere Rf is a perfluoroalkyl group, by means of (B) a salt of perfluoroether carboxylic acid represented by the following general formula:F?CF(CF.sub.3)CF.sub.2 O!nCF(CF.sub.3)COOMwhere M is an alkali metal or an ammonium group, and (C) amide compounds of perfluoroether carboxylic acid represented by the following general formula:F?CF(CF.sub.3)CF.sub.2 O!pCF(CF.sub.3)CONH(CH.sub.2)qNH.sub.2,F?CF(CF.sub.3)CF.sub.2 O!pCF(CF.sub.3)CONH(CH.sub.2 CH.sub.2 NH)rH orF?CF(CF.sub.3)CF.sub.2 O!pCF(CF.sub.3)CONH(CH.sub.2 CH.sub.2 NH)rCOCF(CF.sub.3)?OCF.sub.2 CF(CF.sub.3)!pFhas a high affinity of the fine magnetic particles toward the perfluoropolyether base oil and is effectively used as a sealing material for vacuum apparatus.