Modern Plastics Worldwide - July/August 2009 - dae uptlax

PROCESSING TECHNOLOGY
ExxonMobil Chemical’s Santoprene TPV M350
provides what the company calls “comfort
touch,” and good surface qualities for automotive
interiors.
component injection molding or monosandwich
molding onto a rigid polypropylene
substrate for an unfoamed structure that
does not indent. Either way, ExxonMobil
Chemical says the result is an over-molded
TPV skin with a soft touch. A thermoplastic,
the TPV also has what the company
calls “sustainability opportunities” because
less labor and time are required for production,
with reduced scrap and improved
recycling.
ExxonMobil Chemical Company, Houston,
TX, U.S.A.; +1 281-870-6000;
www.santoprene.com
Compounder teams
carbon fi bers with PPS,
PPA, and PEEK
Specialty compounder LATI Industria
Termoplastici SpA (Vedano Olona, Italy)
has created a new range of injection moldable
“super structural compounds,” pairing
high-temperature, high-performance
engineering thermoplastics polyphenylenesulphide
(PPS), polyphthalamide (PPA),
and polyetheretherketone (PEEK), with
high-modulus carbon-fiber yarns. The
result: the HM (High Modulus) family
of compounds with 40% carbon-fiber
loading for what LATI calls dramatically
higher elastic modulus.
In the development of the compounds—Larton
K/40 HM (PPS),
Laramid D K/40 HM (PPA), and Larpeek
10 K/40 HM (PEEK)—LATI weighed a
mpw.plasticstoday.com
variety of resins, fibers, and compounding
technologies. High-tenacity choppedstrand
carbon fibers are traditionally
applied in thermoplastic compounding
to increase elastic modulus and load
at break without making the materials
brittle. LATI chose to experiment with
high-modulus carbon-fiber yarns, saying
the HM yarns show an elastic modulus
that is almost twice that of HT grades.
LATI also considered the high shear
stress and pressure within a compounding
extruder that can break up fibers,
ultimately affecting the strength they
can impart to the composite. After several
trials, LATI technicians altered the
extrusion parameters and optimized
machine layout, specifically addressing
the carbon-fiber feeding position along
the extruder barrel. In terms of parameters,
LATI says the speed and profile of
the plasticization screw have also been
optimized.
Throught the trials, LATI found it
needed to deal with fiber-bundle buildup
occurring during extrusion and molding,
with the bundles hindering melt flow
and leading to the carbonization of the
polymer, machine jamming, and defective
parts. HM fibers were added up to
45% by weight, and the melt’s viscosity
was closely controlled to avoid poor
molding and material degradation due to
friction and shear. LATI was also careful
to ensure uniform distribution of carbon
fibers in the matrix.
Using ISO-R-527 tensile tests, the
compounder determined the HM materials
achieved tensile strengths above
40,000 MPa, with the PPS-based grade
New developments
reaching 49,000 MPa. By comparison,
LATI says a polyamide 6/6 reinforced
50% with glass fibers, is three times
“softer” than the best HM grade. In
terms of load at break, HM compounds
offer up to 280 MPa (tensile, as per ISO-
R-527) for the PPA-based grade. LATI
says competitive industrial structural
compounds featuring 50-60% glass-fiber
loading achieve around 220 MPa with a
much higher density.
LATI Industria Termoplastici SpA, Vedano
Olona, Italy; +39 0332-409111; www.lati.com
Additives bring tastes,
aromas to plastics
Plastic applications requiring custom taste
and scent enhancements can look to a new
alliance between compounder A. Schulman
Inc. (Akron, OH) and Add the Flavor
LLC (New York), which hopes to commercialize
its Polyflav product as a masterbatch
or additive. Chuck Hampton, A.
Schulman’s North American masterbatch
business manager, sees a variety of end
markets for the technology, telling MPW,
“We envision applications in virtually any
plastic part that may come in contact with
the mouth,” Hampton said. “Items such
as mouthguards, toothbrushes, flossing
devices, waterbottle spouts, etc., have been
discussed.” A. Schulman will add them
to its Polybatch line of specialty additive
masterbatches.
Polyflav comes in two series, S and O,
with both reported to provide long-lasting
flavor. “S” offers a “strong” scent with a
“subtle” taste, according to A. Schulman,
while the “O” or “Optimized” series provides
both strong scent and taste.
Hampton said the materials are FDA
recognized, and several customers are in
sampling and scale-up. The company
expects commercial applications to be in
the field over the next three to six months.
“Now that we have announced to the
public,” Hampton said, “we expect the
pace of projects to heat up as molders seek
to be first to offer a product utilizing this
innovative technology.”
Current flavors include mint, raspberry,
grape, lemon, chocolate, and orange.
A. Schulman Inc., Akron, OH, U.S.A.;
+1 330-666-3751; www.aschulman.com
MODERN PLASTICS WORLDWIDE • JULY/AUGUST 2009 21