The present invention provides high service temperature, low viscosity rubber compounds and hot melt adhesive and/or sealant compositions by combining from 2 to 30% by weight of a polyphenylene ether resin having an I.V. of 0.07 to 0.25 deciliters per gram (dl/g) with from 70 to 98% by weight of an asymmetric radial elastomeric vinyl aromatic hydrocarbon/conjugated diene block copolymer having one of the following formulae: (I) (A--HD).sub.x --Y--(UD).sub.z or (II) (UD--A--HD).sub.x --Y or (III) (UD--A--HD).sub.x --Y--(UD).sub.z wherein A is a vinyl aromatic hydrocarbon block having a weight average molecular weight of from 4000 to 16,000, HD is a hydrogenated conjugated diene block having a weight average molecular weight of from 10,000 to 50,000, Y is a multifunctional coupling agent, UD is a partially hydrogenated conjugated diene block having a weight average molecular weight of from 1000 to 45,000, x is an integer from 2 to 30, z is an integer from 1 to 20, and x+z ranges from 3 to 31. These compositions may be used in adhesive and sealant compositions by adding to them from 20 to 400 parts per 100 parts of copolymer of a tackifying resin.