Continuous fabrication system and method for highly aligned polymer films

Patent metadata

Field	Value
Publication number	US-10427345-B2
Application number	US-201514700284-A
Country	US
Kind code	B2
Filing date	Apr 30, 2015
Priority date	May 7, 2014
Publication date	Oct 1, 2019
Grant date	Oct 1, 2019

Abstract

Process for continuous fabrication of highly aligned polymer films. A polymer-solvent solution is subjected to a high shear, high temperature, Couette flow to extrude a thin film having polymer chain disentanglement. The extruded thin film is frozen and the solvent is allowed to evaporate to form a dried film. The dried film is mechanically drawn using a constant force, adaptive-thickness drawing system to align polymer molecular chains through plastic deformation. A suitable polymer is ultra-high molecular weight polyethylene.

First claim

What is claimed is:

1. Process for continuous fabrication of polymer films comprising:
pumping a polymer-solvent solution of entangled polymer molecular chains through a cylindrical extrusion chamber;
subjecting the polymer-solvent solution of entangled polymer molecular chains to Couette flow as the polymer-solvent solution of entangled polymer molecular chains is pumped through the cylindrical extrusion chamber, to disentangle the entangled polymer molecular chains of the polymer-solvent solution;
pumping polymer-solvent solution including disentangled polymer molecular chains out of the cylindrical extrusion chamber in an outlet direction that is tangential to the cylindrical extrusion chamber to maintain disentanglement of the disentangled polymer molecular chains in the polymer-solvent solution;
dispensing the polymer-solvent solution including disentangled polymer molecular chains as an extruded polymer film including disentangled polymer molecular chains onto a flat substrate;
freezing the extruded polymer film on the flat substrate to cause gelation of the polymer film;
drying the polymer film on the flat substrate to mechanically stabilize the polymer film; and
mechanically drawing the dried polymer film under a constant drawing force sufficient to align the disentangled polymer molecular chains in the polymer film by plastic deformation of the polymer film.

2. The process of claim 1 wherein the polymer-solvent solution comprises ultra-high molecular weight polyethylene.

3. The process of claim 1 wherein drying the polymer film comprises drying by one or more methods selected from the group consisting of mechanical pressing, evaporation or heating of the extruded polymer film, to form a dried polymer film.

4. The process of claim 1 wherein the Couette flow has a shear rate greater than 1000 s −1 .

5. The process of claim 1 wherein the mechanical drawing step is performed within a heated enclosure.

6. The process of claim 1 wherein after the mechanical drawing step, the length of the film is greater than 50 times its original length.

7. The process of claim 1 wherein temperature of the Couette flow is in the range of 50-140° C.

8. The process of claim 1 wherein the mechanical drawing step is performed on a continuous drawing system having dual feed spools and a heated enclosure housing dual sets of draw rollers.

9. The process of claim 1 wherein the mechanical drawing step is conducted with pneumatic cylinders to provide polymer film clamping between draw rollers.

10. The process of claim 1 wherein the mechanical drawing step comprises a mechanical draw selected from the group consisting of multiple-pass draw or single pass draw.

11. The process of claim 1 further comprising transferring the polymer film, after drying, for mechanical drawing, on an automated conveyor belt.

12. The process of claim 1 wherein the polymer-solvent solution includes particles to enhance thermal material properties of the polymer film.

13. The process of claim 12 wherein the particles are graphite or graphene.

14. The process of claim 1 wherein the polymer-solvent solution includes particles to enhance mechanical strength and electrical conductivity of the polymer film.

Assignees

• Massachusetts Inst Technology

Inventors

• Chen Gang
• Wang Jianjian
• Tong Jonathan Kien-Kwok
• Ghasemi Hadi
• Huang Xiaopeng
• Loomis James
• Xu Yanfei

Classifications

• B29K2995/0077

  Yield strength; Tensile strength · CPC title

• D07B2205/201

  Polyolefins · CPC title

• B29C55/06

  parallel with the direction of feed · CPC title

• B29C55/18

  by squeezing between surfaces, e.g. rollers · CPC title

• B29C48/9135

  of flat articles, e.g. using specially adapted supporting means · CPC title