As described in various publications and
worldwide patents dating from 1998, the SER Universal Testing
a true breakthrough and paradigm shift in the field of melt rheometer technology.
Not only has the SER created a buzz of excitement in the world of melt rheology
but in the world of physical material characterization technology as well.
However, looking to capitalize on the early and proven success of the SER, an
imitation technology was introduced that was non-coincidentally
similar in appearance but far less capable than the original model SER-HV. As described below,
the SER offers significant performance advantages over this imitation technology.
The imitation technology is incapable of a very important feature that is critical
to ALL rheological measurements: strain validation. In an attempt to
circumvent the U.S. and worldwide patented technology embodied in the SER, this
imitation technology incorporates a secondary wind-up drum that orbits around a
stationary wind-up drum, akin to the orbital motion of the moon relative to the
earth, as shown below. Unlike the SER fixture that remains fixed while only the
drums rotate, the imitation fixture assembly needs a lot of room as it twirls around
within the oven and with
its exposed gears presents a serious safety hazard to the skin and hands of the user
operating anywhere near the fixture. Although the drum dimensions, securing clamp
design, and sample geometry of this imitation technology are non-coincidentally
identical to that of the SER, as a consequence of said orbital motion, the user has
no clear access to the twirling sample as it undergoes deformation and hence real-time
validation of the applied Hencky strain is near impossible.
Because only the drums of the SER rotate as shown above,
the deformation zone remains in a fixed
plane and the sample deformation can be visualized AT ALL TIMES regardless of the
mode and kinematics of deformation
, whether the SER is used in extensional melt rheology mode,
solids tensile, tear, high-rate fracture, friction, or adhesion/peel testing modes.
This is why the SER is able to provide such nice
videos of sample
deformations while the imitation technology cannot.
Most notably, sample visualization is critical with the flow and deformation of any
non-homogeneous polymer melt blends and compounds, semi-solid networks, foodstuffs, biomaterials, and solid
composite materials where the assumption of bulk deformation uniformity is typically
invalid due to the localized regions of strain deformation within the sample.
Additionally, because the deformation remains in a fixed plane, only the SER can be
utilized with optical characterization techniques such as flow birefringence and
laser, neutron beam & x-ray light scattering during an experiment regardless of the
mode (melt or solid) and kinematics (uniaxial extension, tear, peel, or high-rate
fracture) of deformation.
Another critical shortcoming of the imitation technology lies in the fact that
because the primary and secondary drums are completely de-coupled, the imitation
fixture can only be used on a rotational rheometer in which the torque transducer
and motor are completely separate. Thus, the imitation fixture CANNOT be used
with a controlled stress/strain rheometer – it can only be used on one platform,
the TA/Rheometrics ARES rheometer which is the only controlled strain rheometer
still available on the market. As has been described in several
publications, the SER
can be accommodated onto a multitude of host rheometer systems of either controlled
strain or controlled stress/strain design. Hence, as new rheometer technologies are
acquired in favor of or alongside other legacy rheometer systems, the SER can be
to accommodate the available laboratory rheometer equipment.
Because its primary and secondary drums are de-coupled, ANY deformation with
the imitation technology inherently places a potentially damaging lateral loading
condition on the host rheometer’s torque transducer, as shown below.
Due to the fact that the moment
arm of the dangling stationary drum is much larger than the drum’s radius, the torque
transducer signal is sensitive/susceptible to lateral loads particularly if a
Bendix-type transducer is being used. Additionally, since the imitation fixture
assembly twirls around with the motor, this lateral loading effect is typically
translated non-symmetrically about the axis of the torque transducer as a function
of motor rotation. Thus, factoring out these lateral load effects from the "true"
torque signal response presents a host of concerns, particularly at high rates of
deformation and at elevated stretching forces.
Because the primary and secondary
windup drums of the SER are housed within a rigid chassis, the SER places NO such
lateral load condition on the torque transducer. Hence, unlike the imitation
technology that is limited to low tensile stress applications, the
SER is capable
of not only characterizing the extensional flow behavior of low viscosity polymer
melts but is capable of measuring the physical behavior of high modulus solids.
Another clear distinction of the SER's performance advantages lies in its
remarkable versatility. Unlike the imitation technology, the SER is far more
than just an extensional viscosity fixture. The
SER's broad spectrum of physical
material characterization capabilites allows the user the luxury and freedom
pursue much more, from extensional melt rheology to solids tensile, tear,
peel/adhesion, friction, and high-rate fracture testing. The SER is an extremely
versatile, miniature device that can do anything a conventional linear test
frame can do with solids but at rates ORDERS OF MAGNITUDE higher and with
samples weighing just a few milligrams! Because of its broad performance
capabilities, the SER eliminates the need for expensive testing instruments and
platforms that are far less capable with regard to rates of deformation and
physical material characterization capabilities. The SER's breadth of
capabilities with regard to extensional melt flow rheology characterization
is showcased when hosted on a controlled stress/strain rheometer:
transient extensional viscosity and cessation of extension
results in the controlled rate mode of operation over a very broad range of
Hencky strain rates is clearly exceptional, but tensile creep measurements
in the controlled stress mode of operation even at low tensile creep stresses
The launch of the SER2 model line back in 2007
introduced yet another clear advantage of SER technology over the imitation:
Like the SER2, the new SER3 drums can be configured from any
number of materials of construction, surface coatings and textures, as well as
drum dimensions. Because the SER3 drums are fully detachable, polymer sample
clean-up from the drum surfaces has never been easier - even for the most
challenging of polymer residues, simply remove the drums and soak them in an
appropriate solvent bath for complete sample removal. Whether its sample
clean-up, improved sample gripping, or controlled surface properties
measurements, the detachable drum feature of the SER3 model line gives the user
tremendous flexibility and breadth of capability with regard to physical
Another dramatic advantage of SER technology lies in the fact that
because both of the detachable drums are cantilevered and suspended
from the SER base chassis, the SER3 models that are configured for
use on controlled stress/strain rotational rheometers such as the SER3-P,
SER3-G, SER3-T, and SER3-M are capable of fluid immersion testing.
The drums of said SER3 models can be raised from and lowered into a
controlled temperature fluid environment contained within a jacketed
beaker or other such fluid containment vessel. Applications include
as well as high-temperature silicon oil bath testing to
eliminate any effects associated with molten sample sag at low viscosities.