Vinyl-terminated polybutadiene and butadiene-styrene copolymers containing urethane and/or ester residues, and the electrical laminates obtained therefrom

An electrical laminate, comprising a microwave circuit substrate, which comprises a copper support, and a cured thermosetting composition which is supported on said copper support and which comprises:

• (a) from 20 to 90% by weight of one or more ethylenically unsaturated aromatic monomers having the formula:
• where R1 represents a hydrogen, an alkene group or alkyl groups and n=1, or
• where R1 represents halogen atoms n=1 to 3, and R2 represents a hydrogen atom or an alkyl group;
• (b) from 1 to 50% by weight of a vinyl-terminated polymer (VTP) selected from the group of:
• i. a vinyl-terminated polybutadiene homopolymer containing a urethane group
• ii. a vinyl-terminated butadiene-styrene copolymer containing a urethane group
• iii. a vinyl-terminated polybutadiene homopolymer containing an ester group
• iv. a vinyl-terminated butadiene-styrene copolymer containing an ester group
• (c) from 5 to 60% by weight of a woven fabric, and;
• (d) from 0.01 to 1% by weight of an organic peroxide.