microfoamed polymers

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A Seattle-based company, MicroGreen Polymers, is in the business of creating environmentally
friendly advanced plastic products for everyday use, especially in food packaging. Their latest
technological advancement takes common thermoplastics and creates a microcellular structure
which can then be thermoformed into deep-draw shapes.

A thermoplastic is a deformable material that liquefies when heated and becomes brittle and
glassy when cooled, usually a high molecular weight polymer such as polyethylene, PVC, and
polystyrene. These materials can be remelted and remolded, and are therefore recyclable.
Polyethylene terepthalate (PET) is another material that can be used in their process.
Thermoforming is a process for manufacturing a thin sheet or film of a thermoplastic.

In this process, food-grade CO2 and N2 bubbles are used to create microscopic bubbles
resembling a honeycomb in the plastic itself. Between 50 and 100 of these bubbles can fit on one
human hair. It reduces the material’s density up to 90%, yet it retains the look and feel of a solid
plastic. It develops high temperature resistance, up to 400ºF in PET. This technology also
enables deep-draw thermoforming of expanded thermoplastics with void fractions greater than
80%. Equipment currently in use can also be used for this new material, which also has similar
throughput and cycle times as its solid plastic counterparts. An integral skin is created over the
cellular core structure, which gives it high impact resistance. Upon impact, the core compresses
and absorbs the shock.

This material has applications in the automotive, appliance, electronics, building supplies, and
lighting industries, as well as food and retail packaging. One of the most promising applications
is food packaging. Since the material is highly insulative, it can be used for packaging
refrigerated and frozen foods. It also stands up to mishandling well. It is very cost competitive
with current ovenable/microwavable packaging as well. A possible future development will lead
to this material being used in coffee cups. Since the material is so insulative, it will keep your
coffee hot and your hands cool. One recycled PET pop bottle can produce up to seven coffee
cups, which are also completely recyclable. The material is also 15 to 20 percent cheaper than
the current cups on the market. Also, it saves on costs because “the insulation properties of the
MicroGreen cup are better than doubling two Starbucks cups.” Double-cupping or using a “java
jacket” is no longer needed to keep from burning your hand.

Currently, there are no concrete plans for the coffee cup but according to the Vice President of
MicroGreen, the response has “been receptive”. Discussions have occurred with American
coffee retailers, and also with a European car manufacturer. MicroGreen is designing their own
microwaveable dishware, and has an agreement with a Japanese electronics company who
intends to use the material in their LCD televisions.

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