High melt strength elastomeric copolyesters

A high melt strength, elastomeric, copolyester, comprising:

• the polymeric reaction product of
• (a) terephthalic acid or a 1 to 4 carbon atom dialkyl ester thereof;
• (b) a dimer acid;
• (c) a poly(tetramethylene oxide)glycol having a molecular weight of from about 600 to about 2,000;
• (d) 1,4-butane diol;
• and
• (e) a chain branching agent having the formula ##STR3## where R is an alkyl having from 4 to 20 carbon atoms, a cycloalkyl having from 4 to 10 carbon atoms, an aromatic having from 6 to 10 carbon atoms, or an alkyl substituted aromatic having from 7 to 15 carbon atoms, where x is 0 to at least 3 and up to 6, where y is 0 to at least 3 and up to 6, and where x plus y is at least 3 and up to 12,
• the amount of said terephthalic acid or said dialkyl ester thereof ranging from about 85.0 mole percent to about 99.9 mole percent, and the amount of said dimer acid ranging from about 0.1 mole percent to about 15.0 mole percent, said percentages being based upon the total number of moles of said acid constituents or reactive equivalents thereof,
• the amount of said poly(tetramethylene oxide)glycol ranging from about 2.0 to about 12.0 mole percent and the amount of said 1,4-butane diol ranging from about 88.0 mole percent to about 98.0 mole percent, and
• additionally including a molar excess of said 1,4-butane diol ranging from about 5.0 to about 120 percent, said mole percentages of said excess 1,4-butane diol being based upon the total number of moles of said glycol and said 88.0 to said 98.0 mole percent of said 1,4-butane diol so that the molar ratio of all of said glycol constituents to all of said acid constituents or their reactive equivalents ranges from about 1.05 to about 2.2, and
• from about 0.05 to about 1.0 parts by weight per 1,000 parts of said copolyester produced of said chain branching agent.