| 摘要 |
This invention presents a process whereby thermoplastic polylactic acid polymers foams having the desirable properties for manufacture of thermoformed articles may be made. It has been found that introduction of a dual functional reactive agent into the melt will improve the relevant properties of the melt and thus, the resultant foam. An example of such an agent is pyromellitic di-anhydride, but it is envisioned that a wide number of dual functional reactive agents can be utilized. It has been found that such dual functional reactive agents do not shift crystalline melt point of the material by any appreciable amount. It has been found that, by carefully controlling such a reaction, melt strength can be increased sufficiently to produce stable foam at temperatures above the melt point of the polymer, to permit the production of foamed polylactic acid polymer and product formed therefrom on conventional process equipment.
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