Issue 02/2016

Thermoforming / Rigid Packaging
a-PHA modified PLA
for thermoforming
Recent reports indicate an emerging market trend
toward sustainable packaging options due to environmental
awareness among consumers for alternatives
with improved biodegradability. For instance, the
Foodservice Packaging Institute’s 2015 Trends Report
found that there was an increasing focus on compostable
packaging and the expectation is that more companies
will need to address the demand for sustainable
packaging applications in the near future.
PLA is one of the more commonly used biopolymers
in industrial compostable applications. Because
PLA is derived from renewable sources, it is a sought
after solution for green packaging material. It is well
understood that the physical properties of PLA can
present challenges during processing as well as in
the performance of finished articles. One problem is
the inherent brittleness and relatively low toughness
of PLA that can present challenges in adapting the
biopolymer to new packaging applications. For example,
petroleum-based performance modifiers diminish
biobased content and at increased addition rates can
compromise compostability. This underscores the need
to identify new additives for PLA that improve properties
while maintaining biobased content and industrial
compostability.
Metabolix, a leader in PHA (polyhydroxyalkanoate)
technology, launched a new amorphous PHA (a-PHA)
biopolymer material in 2015. This a-PHA specialty
material is a high molecular weight, low T g
rubber that
extends the additive space for PHA materials. Metabolix
has reported research demonstrating the use of its
a-PHA as process aids and performance modifiers for
PVC as well as performance modifiers for PLA. It should
be noted that the results produced with a-PHA in PVC
and PLA are far superior to those using semi-crystalline
versions of PHA.
Metabolix has shown that a-PHA is an effective modifier
for PLA across a range of applications including food and
consumer product packaging, film, food service ware,
3D printing filament, fibers and nonwovens. In sheet and
thermoforming applications specifically, adding a-PHA at
low loading levels (such as less than 5 %) can eliminate
the brittle fracture commonly associated with the edge
trimming, conveying and cutting of extruded sheets and
thermoformed parts. Adding a-PHA also increases the
impact strength of the finished part, and at loading levels
up to 10 %, an increase in toughness and ductility can be
achieved to such an extent that it prevents brittle failure
and splintering under impact load. Ultimately, a-PHA
modified PLA shows an excellent balance of properties
and is not limited to the 1 % loading limit of a noncompostable
modifier per ASTM D6400.
PLA modified with a-PHA represents an attractive
option for producing thermoformed containers for food
service ware. These containers have high biocontent
and are industrially compostable, per ASTM D6400 and
EN13432. Furthermore, the containers are strong, and
because PHA and PLA are biopolymers with similar
refractive indices, the containers retain a very high level
of clarity.
Consumers, brand owners and regulators continue to
drive incentives to utilize sustainable packaging materials
for carry out options as well as divert food waste from
landfills. Companies looking to meet growing demands
for compostable packaging
options should explore
a-PHA modified PLA
materials as a solution
for their food service and
consumer packaging
applications.
www.metabolix.com
By:
Michael Andrews
Director Product and Application Development
Metabolix, Inc.
Lowell, Massachussetts, USA
14 bioplastics MAGAZINE [02/16] Vol. 11