Page 37 - Plastics Nuews October 2017

Another cost factor to consider is that associated with a Testing molds in a virtual simulation environment cuts
design change in the prototyping stage. In 3D printing, across communication barriers and allows designers,
there is no cost of modifying a mold for a prototype moldmakers, and manufacturing professionals to
iteration. Design changes are simply made to the CAD collaborate eff ectively, while eliminating the need for
model. Within injection molding, design changes with costly prototype and mold cycles.
a steel mold are typically easy to make and relatively When it comes to 3D printing versus injection molding,
inexpensive, but with aluminum molding tools, a design the best production method for your parts will become
change may require the expense of all new tooling.
clear when you can answer these questions regarding your
Additionally, new simulation software is now available to desired quantity, quality and cost.
help resolve injection molding challenges in software -
rather than through costly, time-consuming prototyping
iterations.

The Cool Plastic film

Xiaobo Yin, a materials scientist at the University of Colorado in Boulder has developed Plastic
film that cools whatever it touches

f heat is not your thing, rejoice: A thin plastic sheet may and even people—absorb visible and near-infrared (IR)
Isoon provide some relief from the intense summer sun. light from the sun. That added energy excites molecules,
The film, made from transparent plastic embedded with which warm up and, over time, emit the energy back out as
tiny glass spheres, absorbs almost no visible light, yet
pulls in heat from any surface it touches. Already, the new photons with longer wavelengths, typically in the midrange
material, when combined with a mirrorlike silver film, has of the infrared spectrum. That helps the materials cool
been shown to cool whatever it sits on by as much as 10°C. back down, particularly at night when they are no longer
And because it can be made cheaply at high volumes, it absorbing visible light but are still radiating IR photons.
could be used to passively cool buildings and electronics
such as solar cells, which work more efficiently at lower In recent years, researchers have tried to goose this
temperatures. “passive cooling” effect by making materials that absorb
as little visible light as possible yet continue to emit mid-
During the day most materials—concrete, asphalt, metals,
IR light. In 2014, for example, researchers led by Shanhui
Fan, an electrical engineer at Stanford University in Palo
Alto, California, created a sandwichlike film of silicon
dioxide (glass) and hafnium dioxide that reflected almost
all the light that hit it while strongly emitting mid-IR
light, a combination that allowed it to cool surfaces by
as much as 5°C. Still, Fan and his colleagues had to use
clean room technology to make their films, a costly process
that doesn’t work well on a large scale.

When Xiaobo Yin, a materials scientist at the University
of Colorado in Boulder, saw Fan’s paper, he noticed the
material worked in part by encouraging infrared photons

37 Octob er 2017 | Plastics News