Forced Assembly Coextrusion
Forced assembly” polymer coextrusion is a processing technique based on layer multiplication dies to produce films with tens or thousands of micron to nanometer thick layers. To date, “forced assembly” coextrusion has been limited due to the use of equal splitting layer multipliers. The development of novel “uneven” split layer multiplying dies has enabled the production of multilayered polymer films with different layer thickness distributions. Coextrusion through a series of “uneven” split multiplier dies has successfully produced multilayered polymer films with up to a 10X difference between the thickest and thinnest layers. Coupling “forced assembly” coextrusion processing with the existing equal and “uneven” split multiplier dies allows for unparalleled flexibility in the design and processing of different gradient multilayer film distributions by: (1) altering the off-set magnitude of the die splitting ratio and (2) changing the sequencing of a series of “uneven” split layer multiplying dies with different off-set splitting ratios.
The added flexibility in the design of gradient layer thickness distributions allows for the development of polymer films with unique properties for a variety of applications. Highly reflective, multilayered polymeric photonic crystal film systems have been developed. Inclusion of step, or gradient, layer thickness distributions within these photonic film systems resulted in widening the optical reflection band, and in some cases, produced multiple optical reflections within a single film. These gradient micro- or nanolayered photonic crystal films can be tailored to give optical reflections in UV, visible, or NIR wavelengths based on individual layer thicknesses in the micron or nanometer thickness range.
(Ponting, Hiltner and Baer, Forced Assembly Coextrusion, 2011 AICHE Annual Meeting, 1/14/2011)
Forced assembly polymer coextrusion utilizes layer multiplication to produce films with tens or thousands of micrometer to nanometer thick layers.
[Ponting et al (12111–12118) Industrial & Engineering Chemistry Research 49 #23 (2010)
Recent Journal Articles
12/3/2010
Gradient Multilayer Films by Forced Assembly Coextrusion
(12111–12118) Industrial & Engineering Chemistry Research 49 #23 (2010)
Ponting et al developed uneven split layer multiplying dies for producing gradient multilayer films with at least a 10 times difference between the thickest and thinnest layers. Coextrusion through a series of equal and uneven split multiplier dies allows for flexibility in the unique design of layer thickness distributions by: (1) altering the multiplier offset and (2) changing the sequence of a series of uneven split multiplying dies with different splitting ratios. This new technology has created highly reflective, multilayered photonic films with gradient layer thickness distributions exhibiting, as examples, a 600 nm wide reflection band and dual optical reflection bands within a single film. (RDC 12/8/2010)