Amorphous polyester composition and method of making

A method of making an amorphous polyester foamable resin composition comprising the steps of:

• combining at room temperature in a reactor, a crystalline or semi-crystalline polyester, optionally derived from a recycled waste stream, with at least one diol or aromatic diacid or an ester of a diacid or a hydroxycarboxylic acid or a lactone or a dianhydride, and in the presence of a catalyst,
• sealing and purging the reactor with an inert gas,
• mixing the contents,
• evacuating the reactor of volatile components,
• flushing the reactor at least once with an inert gas,
• increasing the temperature of the reactor to between 250-350 degrees C. over a period of from 30 to 90 minutes,
• mixing the molten material combination
• maintaining a temperature of between 250-350 degrees C. for between 20 to 150 minutes,
• evacuating the reactor to minus 25 inches of mercury or lower,
• continuing the reaction at a temperature of from 250-350 degrees C. for between 100 to 300 minutes, optionally while removing volatile species via a distillation column, and
• stopping the reaction by ceasing mixing, purging the reactor with an inert gas, returning the reactor to atmospheric pressure and reducing the temperature to 100 degrees C. or lower,
• wherein the resultant composition has a weight average molecular weight of at least 10,000 g/mol (polystyrene equivalent molecular weight) as measured by gel permeation chromatography) and a degree of crystallinity no greater than 5% as determined by differential scanning calorimetry.