Date: Aug 17, 2012 Source: AzoNano (
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Introduction
The ability to produce superior-quality uniform CNF-reinforced polymer films has been developed by ASI. The thin film materials from ASI are suited to be used as fully-cured surface coating materials or as pre-pegging sheets for EMI shielding.
A Navy Phase II Small Business Innovative Research (SBIR) program was awarded by ASI to refine the production methodology for these products and also to produce pilot scale thin films. This program will be based on the success from a Navy Phase I SBIR where a new proprietary film production method was demonstrated.
Benefits of ASI's Thin Film Technology
The advantages of ASI's thin film technology are:
Uniform conductivity
Low filler content
Thin material with properties equivalent or better than legacy materials
Great product for pre-pregging
All the benefits of carbon nanofiber in a closed-form solution
Background
Inks and conductive films are used for electrostatic dissipation as well as EMI shielding in aircraft, electronics and aerospace applications. The fabrication of these materials is done using conductive materials like metal flakes and carbon black.
Carbon black needs high resin film loadings and it is possible that inks negatively effect the reliability of the resultant coatings and films. Using metal flakes in these application types has restrictions that are related to high particle loadings needed to reach resistivity targets. Additionally, corrosion and compatibility with the polymer matrices also exist.
Since carbon nanomaterials (CNM) are becoming a mature technology, and are being manufactured in bulk, it is essential to use CNM in conductive films and inks. The capability to achieve low electrical resistivity targets at minimal filler loading lies in the high electrical conductivity and aspect ratio of graphitic nanotubes and nanofibers.
Successful Demonstration of Film Properties During Navy Phase I Research
By using nano-scale reinforcements and the suitable application, ASI capitalized on the promise of these materials during a Navy Phase I SBIR program to improve polymeric film performance which meets all of the Navy's requirements at a lower thickness hence less parasitic mass when compared to legacy materials. The Phase II program will follow-up the Phase-I program by proving in the capacity for commercial manufacture.
Production Process
Considerable progress was achieved in both the conductive solution formulation and the film production processing methods. According to this program, ASI determined a synergistic and effective combination of graphitic nanomaterials. The material blend balanced uniformity and conductivity while enabling control of the percolation threshold and minimizing loading of graphitic nano-scale additives. Also both the selected polyimide resin and conductive additives are commercially available at low cost and in huge volumes. An effective and readily-scalable dispersion protocol for preparation of the film-forming conductive solutions was determined using dispersion analysis. The ASI-developed process is beneficial in the fact that scaling-up production to larger area films will require purchase and modification of rightly-sized commercially available equipment as against design and fabrication of custom equipment.
By using the equipment assembly used in the Phase I feasibility, it was determined that preparing uniform, robust films was quite quick and consistent. ASI film materials are thinner than the conventionalmaterial, while exceeding or meeting all the Phase I program goals hence enabling reduction in weight. These materials exceeded or met the bend testing and solvent resistance requirements.
Potential Applications
By developing more robust, conductive thin polymer films, a number of commercial electronics applications and commercial aircraft applications will be benefited. It will be beneficial to defense applications as there will be an increase on conductive film lifetime when compared to materials being used presently.
