More Choices in Nylon, Polypropylene Nanocomposites Available Soon
Following a trickle of R&D announcements last year, nanocomposites -- resins that incorporate chemically-engineered additives with particle sizes in the nanometre range (10-9m) -- are poised for comme...
Following a trickle of R&D announcements last year, nanocomposites — resins that incorporate chemically-engineered additives with particle sizes in the nanometre range (10-9m) — are poised for commercial breakthrough this year. Nanocomposite materials show significant increases in strength, heat resistance and barrier properties.
Peter Maul, president of Nanocor, Inc., expects several nylon suppliers worldwide to announce this year the availability of nylon nanocomposites produced by a polymerization technique, and about six compounders in North America to produce nanocomposite nylons by extrusion compounding techniques. Nanocor produces chemically modified, nano-sized Nanomer clays for addition to thermoplastic and thermoset resins.
A line of nylon 6 nanocomposites, in both molding and film grades, is now available from RTP Company, a custom compounder.
“We are working on extending the nanoclay additive to other resin systems, particularly polyolefins, but these are not ready commercially,” says Sam Dahman, product development engineer with RTP. He expects new nanocomposite grades to be ready before the end of the year.
Nanocor has nanoclay additives for nylon 6 and 6/6 molding grades, homopolymer polypropylene, EVOH, and a specialty aromatic nylon for film.
For PET, Nanocor has an exclusive development agreement with Eastman Chemical Co. Of the developments in that field, Maul can only say, “There will be a PET nanocomposite resin available sometime in the near future.” Eastman and Nanocor are also pursuing multi-layer barrier technology for bottles whereby a layer of high-barrier nanocomposite nylon is sandwiched between PET. This multi-layer technology will be appropriate for highly oxygen sensitive products, such as beer, fruit juices and tomato products, says Maul.
SMALL PARTICLES, LARGE IMPACT
The Nanomer additives are chemically modified clay platelets, which measure about one nanometer thick and one micron long. One nanometre is one thousandth of a micron, so the platelets have an aspect ratio approaching 1000.
In nylon nanocomposites, RTP Co.’s Dahman says there are three main properties that show significant improvement. Heat resistance, as measured by heat deflection temperature, typically increases to 100C, compared with 65C for unfilled nylon 6. Stiffness, measured by flexural modulus, increases from 2.9 to 4.3 GPa compared with unfilled nylon 6.
Most important for the film grades, nylon augmented with
nano-clays achieves an oxygen transmission rate of 0.5 cc-mil/100 sq.in.-24 hr-atm, while an average oxygen transmission rate for unfilled nylon 6 is about 2.0, says Dahman.
Another interesting effect of the nanoclay additives is the increased rate of crystallization for nylon. Molders can get significantly shorter cycle times because of the faster crystallization, says Maul.
In polypropylene, Maul reports Nanomer additives can increase the material’s strength by about 50 percent and its heat deflection temperature by 25 percent.
Can any compounder produce nanocomposites? “We didn’t need any additional equipment,” says Dahman, “but knowledge of the compounding process and the nanoclay product does matter.”
RTP Co. (800/433-4787)
Nanocor Inc. (888/626-6633)