A Rhode
Island compounder says it has improved impact strength and heat deflection
temperatures for a major bioplastic.
As a result,
the material, polylactic acid (PLA), may become a candidate for injection-molded,
semi-durable and durable applications. The bioplastic is also now better suited
for high-end disposable food service items such as cutlery, coffee lids and
containers for microwavable products.
Teknor Apex says it has overcome an inverse relationship between heat
distortion temperature (HDT) and Izod impact strength in PLA, creating a new
series of compounds, Terraloy BP-34001, that provide up to two times the HDT
and up to six times the impact strength of standard PLA resins.
Previous work
to enhance PLA performance beyond standard levels had generated resins with
either higher HDT or greater impact strength - but not both in the same grade,
according to the Bioplastics Div. of Teknor Apex.
There are other
benefits to the newly developed PLA compound.
In
comparison with previous enhanced-performance PLA resins, the new Terraloy compounds
process faster - cycle times are 28 to 30 percent shorter.
Another
benefit: The compounds incorporate a larger percentage of renewably resourced
content, about 10 to 30 percent more. Nearly all of the new Terraloy compounds are
said to comply with FDA requirements for food-contact applications.
"Terraloy
BP-34001 Series compounds dramatically improve the heat and impact resistance
of PLA while largely retaining the environmental benefit of this polymer as a
bioplastic," says Edwin Tam, manager of new strategic initiatives. "These
innovative formulations promise to expand the applicability of PLA, making
possible new uses in higher-heat food service items as well as consumer goods."
In property
tests, a typical grade in the new series, Terraloy BP-34001D, exhibits a heat
distortion temperature of 112C and Izod impact strength of 135 J/m. By
comparison, approximate values for standard PLA are 65C and 33 J/m. The new
compound complies with
FDA 21 CFR requirements and has a renewable
content of 78 percent.
The base
polymers for Terraloy BP-34001 products are Ingeo resins supplied by
NatureWorks.
"Teknor Apex built upon research by NatureWorks
to develop higher-performance PLA compounds," says Gregory J. Anderson, Teknor
Apex technical manager. "By discovering alternative formulations and
compounding techniques, we succeeded in eliminating a chronic property trade-off
between heat resistance and impact resistance, while improving processability
and reducing the petrochemical content."
Tam says
that the price for the PLA compound will be greater than for standard PLA. No
specific data was available.
The
Bioplastics Div. of Teknor Apex is a custom compounder of plastics derived from
renewable resources. Product families include: hybrids that combine
thermoplastic starch (TPS) with standard petrochemical-based polymers such as
polyolefins or polystyrene; biodegradable or compostable blends of bioplastics;
recycled-content hybrids that combine post-industrial or post-consumer polyolefins
with TPS; and PLA-based masterbatches that incorporate additives such as impact
modifier or melt strength enhancers.
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