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Get more bounce in your running shoes
Runners always stress the need for good cushioning when it comes to run-
ning shoes. This is the function of the midsole—in just a few milliseconds, it
absorbs the kinetic energy generated by the runner as the foot lands—and re-
turns some of it to the runner while the foot is pressed down. Runners previ-
ously had to choose between wearing hard, elastic competition shoes or very
soft training shoes with a lot of cushioning. But that is about to change.
In less than three years, adidas and BASF, both in Germany, resolved this
dilemma with the development of adidas BOOST technology using an ex-
panded thermoplastic polyurethane (ETPU) material called Infinergy from
BASF. To produce this innovative material, researchers expanded BASF’s ther-
moplastic polyurethane (TPU), Elastollan, using an innovative procedure that
preserves the benefits of TPU while adding foam properties. The material
does not lose its resilience even when under continuous load. During high-fre-
quency fatigue testing using dynamic loads at five cycles per second and a
constant pressure of 250 kilopascals, the material performed about 75% bet-
ter than expanded polyethylene (EPE). After 40,000 load cycles, the thickness
of the ETPU test piece was still 37 mm (from a 40 mm starting figure),
whereas the EPE material remained permanently compressed and thickness
was reduced to about 9 mm. , .
Cardboard cathedral built in New Zealand
A temporary cathedral made out of cardboard opened in New Zealand last
year in the heart of Latimer Square to replace a neo-Gothic structure that was
destroyed in the massive Christchurch earthquake in 2011. The cardboard
structure was designed by Japanese architect, Shigeru Ban, and is built from
cardboard tubes measuring 600 mm in diameter coated with water-resistant
polyurethane and flame retardants. The innovative cardboard cathedral has
a simple A-frame structure that rises 78 ft (24 m) and can accommodate 700
people. Despite being made from cardboard, the cathedral can last up to 50
years. The Anglican Church in New Zealand plans to use the cardboard struc-
ture for at least 10 years while building a more permanent replacement for
the original cathedral. The cardboard church has a concrete base with tubes
holding up the two sides of the A-frame structure. Containers were also placed
to secure the walls of the cathedral. On one end of the cathedral, a polycar-
bonate roof and stained glass protect the structure from the elements.
.
Safer football helmets prevent concussions
University of California Los Angeles professor Vijay Gupta is applying his expertise
in materials science, mechanical engineering, and bioengineering to protect the brain
from forces that cause concussions and traumatic brain injury. He created a polymer
that could diminish the force of helmet-to-helmet hits on a football field or shockwaves
from explosive devices on a battlefield. To test out his material, Gupta uses lasers and a
grandfather-clock-sized hammering machine. To improve on the shock-absorbing abil-
ity of the standard football helmet without radically changing its design, Gupta added a
2-mm-thick wafer of a firm but flexible polymer he devised to reinforce the helmet’s
foam padding. Then Gupta and his students used the hammering machine to drop a
weight on top of the helmet from a specified height to generate a range of G-forces. They
measured the force felt by using a sensor. The new design has yielded promising results
and achieves up to a 25% percent reduction in the force a person would feel. This trans-
lates to a similar reduction in the probability of getting a concussion. .
ADVANCED MATERIALS & PROCESSES • JULY 2014 5
interest
of material
The opening and dedication of New Zealand’s
cardboard cathedral was a major milestone in the
ongoing recovery of Christchurch, which was hit
by a 6.3 magnitude earthquake that leveled much
of the downtown area in 2011.
This 2-mm-thick polymer
wafer shows promise as a
way to decrease
concussion risks.
Infinergy is the world’s first expanded
thermoplastic polyurethane (ETPU). This closed-
cell particle foam exhibits excellent resilience
and especially high durability over a wide
temperature range. Courtesy of BASF/adidas.