Viscoelastic Extrusion Processing Method and Compositions for Biopolymers
A viscoelastic extrusion process (VEEP) for biopolymers such as polylactic acid is provided. The VEEP process removes many processing and performance limitations of PLA as well as creates performance sufficient to produce durable “nonbiodegradable” products as a direct replacement for PVC and other petrochemical profile and sheet extrusion applications. The VEEP process also retains a high degree of crystallinity within the PLA for increasing toughness and to lower its biodegradability. The invention also includes an integral process wherein rheology is highly modified to allow profile extrusion and higher melt strength wherein processing is lower than the melting point of the primary biopolymer and below the browning points of the natural fibers in the biopolymers viscoelastic state.
1 . A method of processing polylactic acid (PLA) using a viscoelastic process, comprising:
processing the PLA below its melt processing point to form a profile;
wherein the PLA maintains a high degree of crystallinity after processing.
2 . The method of claim 1 , wherein processing is done between 250° F. and 360° F.
3 . The method of claim 2 , wherein processing is done between 300° F. and 340° F.
4 . The method of claim 1 , wherein the PLA remains cloudy during processing.
5 . The method of claim 1 , wherein the profile is suitable for replacing a PVC profile.
6 . The method of claim 1 , wherein a biodegradability of the PLA is reduced.
7 . The method of claim 1 , further comprising adding a filler to the PLA.
8 . The method of claim 1 , further comprising adding an additive to the PLA.
9 . The method of claim 1 , further comprising extruding the PLA to form the profile, wherein the profile is a high tolerance three dimensional shape.
10 . A method of viscoelastic processing of polylactic acid (PLA), comprising:
heating the PLA to a temperature below its melt processing point such that it is in a molten state, and
extruding the molten PLA to form a high tolerance crystalline profile extrusion component.
11 . The method of claim 10 , wherein the profile component comprises a baseboard.
12 . The method of claim 10 , wherein the profile component comprises a window profile.
13 . The method of claim 10 , wherein the profile component comprises an edgebanding.
14 . The method of claim 10 , wherein the profile component comprises architectural millwork.
15 . The method of claim 10 , wherein the profile component comprises an architectural corner guard.
16 . The method of claim 10 , wherein the profile component comprises a door component.
17 . The method of claim 10 , wherein the profile component comprises a pipe.
18 . The method of claim 10 , wherein the profile component comprises a replacement for rigid PVC profiles.