Issue 01/2016
Automotive Foam Basics: Public Procurement
Automotive
Foam
Basics: Public Procurement
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Automotive<br />
This new compounding technology proved to be the first leg<br />
in the triad of developments that led to success.<br />
Find the best fiber for the job<br />
When it comes to reinforcing polypropylene with natural<br />
fiber, many routes, variables, and choices can have a<br />
significant influence on the final solution:<br />
• type of PP (homo- or copolymer)<br />
• melt index<br />
• type of reinforcing fiber<br />
• coupling technology<br />
• manufacturing process<br />
A design of experiment (DOE) helped reduce these input<br />
variables down to three: the type of fiber, coupling technology<br />
for the fiber and the PP, and manufacturing process<br />
(compound extrusion). PolyOne’s R&D experts already<br />
had developed what the researchers felt might be the best<br />
manufacturing process, but they needed to find the right<br />
materials. A PP homopolymer was determined to be the<br />
optimal matrix material with the appropriate melt index.<br />
So the best fiber for the applications targeted needed to<br />
be found, and a coupling technology to enable these fibers<br />
to bond well with the thermoplastic matrix material. Natural<br />
fibers made sense because of their low density; but to serve<br />
the automotive industry, fibers need to be available globally,<br />
with consistent sizing and quality.<br />
Testing of many types of natural fiber led to an engineered<br />
fiber, available globally as a modified product of an established<br />
wood fabrication industry. These fibers are supplied with<br />
consistent length and thickness, facilitating production<br />
of a compound with consistent properties – if the new<br />
compounding technology was able to evenly distribute the<br />
fibers throughout the matrix material, and helped create a<br />
powerful bond between fiber and matrix material.<br />
A powerful bond<br />
The best fibers would be worth little if they could not be<br />
properly mixed into and bonded with the thermoplastic matrix.<br />
PolyOne’s search for solutions to these challenges led them to<br />
a coupling technology that forged the necessary bond, as seen<br />
in Graph 1. Coupling Technology 1 is an advanced technology<br />
while Coupling Technology 2 is a more classical technology.<br />
Coupling Technology 1 was tested on multiple fibers but<br />
ultimately PolyOne settled on the natural engineered fiber<br />
mentioned earlier.<br />
Testing began to determine whether the positive results<br />
seen in lab testing could be maintained at commercial<br />
scale. In addition, it needed to be investigated whether the<br />
new compounding process had an influence on the property<br />
profile at various reinforcing fiber amounts (30 % and 40 %<br />
in weight).<br />
The properties of the material manufactured on industrial<br />
scale machinery are very similar to the original target, and<br />
realize a density reduction versus short glass fiber alternatives<br />
of at least 5 % (Graph 2). The new formulations were named<br />
reSound NF natural fiber reinforced solutions; reSound is<br />
PolyOne’s brand name for formulations that contain 30 % or<br />
more of renewably resourced materials. u<br />
By:<br />
Marc Mézailles<br />
Global Automotive Industry Manager,<br />
PolyOne Corporation<br />
Lyon, France<br />
Photo 1: Lightweight and strong: Tests have proven the mechanical<br />
performance of parts molded from reSound NF natural fiber<br />
reinforced solutions.<br />
bioplastics MAGAZINE [<strong>01</strong>/16] Vol. 11 13