 Lab Services
Whether it's a specific test or a program to qualify your
product to your customer, we can provide the plastic recycling service you
need. NPI has labs at both of its plants and provides lab services from the Brampton location. All
tests are performed to ASTM standards. Lab testing capabilities include:
Our lab processing equipment includes:
- Lab Film Line
- Lab Pelletizing Line 2
- Lab Injection Molders.
We are always in the market for buying post-industrial feedstocks which
include plastic films and molding regrinds. If you are interested please
contact us and provide us with a representative sample of your material which
we will quickly qualify in our lab.
Melt Index - back
Melt Flow Rate measures the rate of extrusion of thermoplastics through an
orifice at a prescribed temperature and load. It provides a means of
measuring flow of a melted material which can be used to differentiate grades
as with polyethylene, or determine the extent of degradation of the plastic
as a result of molding. Degraded materials would generally flow more as a
result of reduced molecular weight, and could exhibit reduced physical
properties. Typically, flow rates for a part and the resin it is molded from
are determined, then a percentage difference can be calculated.
Alternatively, comparisons between "good" parts and "bad"
parts may be of value.
Test Procedure:
Approximately 7 grams of the material is loaded into the barrel of the melt
flow apparatus, which has been heated to a temperature specified for the
material. A weight specified for the material is applied to a plunger and the
molten material is forced through the die. A timed extrudate is collected and
weighed. Melt flow rate values are calculated in g/10 min.
Test Specimen Size:
At least 14 grams of material is needed.
Data:
Flow rate = ( 600/t x weight of extrudate)
t = time of extrudate in seconds
melt flow rate = g/10 min.
The melt index of a resin describes the flow behavior that can be expected
during processing. It usually varies due to the average molecular weight of
the polymer. The melt index refers to the amount of resin in grams of a
thermoplastic material which can be forced through a 0.0825 inch orifice when
subjected to 2160 grams of force in 10 minutes at 190° C. If the melt index
of a resin is high, the melt flow resistance during processing is low. That
is, the material flows through a mold or extruder die faster than a resin
with a low melt index.
Izod Impact - back
Notched Izod Impact is a single point test that measures a materials
resistance to impact from a swinging pendulum. Izod impact is defined as the
kinetic energy needed to initiate fracture and continue the fracture until
the specimen is broken. Izod specimens are notched to prevent deformation of
the specimen upon impact. This test can be used as a quick and easy quality
control check to determine if a material meets specific impact properties or
to compare materials for general toughness.
Test Procedure:
The specimen is clamped into the pendulum impact test fixture with the
notched side facing the striking edge of the pendulum. The pendulum is
released and allowed to strike through the specimen. If breakage does not
occur, a heavier hammer is used until failure occurs. Since many materials
(especially thermoplastics) exhibit lower impact strength at reduced
temperatures, it is sometimes appropriate to test materials at temperatures
that simulate the intended end use environment
Reduced Test Procedure:
The specimens are conditioned at the specified temperature in a freezer until
they reach equilibrium. The specimens are quickly removed, one at a time,
from the freezer and impacted. Neither ASTM n or ISO specify a conditioning
time or elapsed time from freezer to impact - typical values from other
specifications are 6 hours of conditioning and 5 seconds from freezer to
impact.
Specimen Size:
The standard specimen for ASTM is 64 x 12.7 x 3.2 mm (2½ x ½ x 1/8 inch). The
most common specimen thickness is 3.2 mm (0.125 inch), but the preferred
thickness is 6.4 mm (0.25 inch) because it is not as likely to bend or crush.
The depth under the notch of the specimen is 10.2 mm (0.4 inches). The
standard specimen for ISO is a Type 1A multipurpose specimen with the end
tabs cut off. The resulting test sample measures 80 x 10 x 4 mm. The depth
under the notch of the specimen is 8mm.
Data:
ASTM impact energy is expressed in J/m or ft-lb/in. Impact strength is
calculated by dividing impact energy in J (or ft-lb) by the thickness of the
specimen. The test result is typically the average of 5 specimens. ISO impact
strength is expressed in kJ/m2. Impact strength is calculated by dividing
impact energy in J by the area under the notch. The test result is typically
the average of 10 specimens. The higher the resulting number, the tougher the
material.
Ash Content - back
The Ash Content test is used to determine the amount of fillers in a specimen
after the polymer has been burned off. The ash can be looked at under a
microscope to determine its basic identification such as glass or mineral.
Test Procedure:
Generally, a 2 gram sample is weighed out and placed into a dried crucible.
The sample is then burned in a muffle furnace at 600 degrees C until the
entire polymer has been burned off. The crucibles are then placed into a
desiccator to cool. The ash that is left in the crucibles is then weighed to
give the ash content of the specimen.
Specimen Size:
A 2 gram sample weight is often used.
Data:
Ash content is the weight of the ash divided by the weight of the original
sample multiplied by 100 to give a percentage.
Density - back
Bulk density (see density below) is defined as the weight
per unit volume of material. Bulk density is primarily used for powders or
pellets. The test can provide a gross measure of particle size and dispersion
which can affect material flow consistency and reflect packaging quantity.
Test Procedure:
A funnel is suspended above a measuring cylinder. The funnel is filled with
the sample and allowed to freely flow into the measuring cylinder. The excess
material on top of the measuring cylinder is scraped off with a straight
edge. The sample and the cylinder is then weighed and the weight / volume
(Bulk Density) is determined.
Specimen Size:
Powder or Pellets
Data:
Apparent density value is recorded as g/cm3.
Density
Density is the mass per unit volume of a material. Specific gravity is a
measure of the ratio of mass of a given volume of material at 23°C to the
same volume of deionized water. Specific gravity and density are especially
relevant because plastic is sold on a cost per pound basis and a lower
density or specific gravity means more material per pound or varied part
weight.
Test Procedure:
There are two basic test procedures, Method A and Method B. The more common
being Method A, can be used with sheet, rod, tube and molded articles. For
Method A, the specimen is weighed in air then weighed when immersed in
distilled water at 23°C using a sinker and wire to hold the specimen
completely submerged as required. Density and Specific Gravity are
calculated.
Specimen Size:
Any convenient size.
Data:
Specific gravity = a/[(a + w)-b]
a = mass of specimen in air.
b = mass of specimen and sinker (if used) in water.
W = mass of totally immersed sinker if used and partially immersed wire.
Density, kg/m3 = (specific gravity) x (997.6)
DSC - back
Using a DSC (differential scanning calorimeter) the following are commonly
found:
Tg = Glass Transition Temperature = The temperature (°C) at which
an amorphous polymer or an amorphous part of a crystalline polymer goes from
a hard, brittle state to a soft, rubbery state.
Tm = melting point = The temperature (°C) at which a crystalline
polymer melts.
Hm = the amount of energy in (joules/gram) a sample absorbs while
melting.
Tc = crystallization point = is the temperature at which a polymer
crystallizes upon heating.
Hc = the amount of energy (joules/gram) a sample releases while
crystallizing. The data can be used to identify materials, differentiate
homopolymers from copolymers or to characterize materials for their thermal
performance.
Test Procedure:
A sample of 10 to 20 mg. in an aluminum sample pan is placed into the
differential scanning calorimeter. The sample is heated at a controlled rate
(usually 10°/min) and a plot of heat flow versus temperature is produced. The
resulting thermogram is then analyzed.
Specimen Size:
A sample weight of 10 to 20 mg is used.
Data:
A thermogram is produced which can provide Tg, Tm, Hm or Hc.
Flexural Test - back
The Flexural test measures the force required to bend a beam under 3 point
loading conditions. The data is often used to select materials for parts that
will support loads without flexing. Flexural modulus is used as an indication
of a material's stiffness when flexed. Since the physical properties of many
materials (especially thermoplastics) can vary depending on ambient
temperature, it is sometimes appropriate to test materials at temperatures
that simulate the intended end use environment.
Test Procedure:
Most commonly the specimen lies on a support span and the load is applied to
the center by the loading nose producing three point bending at a specified
rate. The parameters for this test are the support span; the speed of the
loading; and the maximum deflection for the test. These parameters are based
on the test specimen thickness, and are defined differently by ASTM and ISO.
Elevated or Reduced Temperature Test Procedure:
A thermal chamber is installed on the Instron universal test machine. The
chamber is designed to allow the test mounts from the base and crosshead of
the Instron to pass through the top and bottom of the chamber. Standard test
fixtures are installed inside the chamber, and testing is conducted inside
the controlled thermal environment the same as it would be at ambient
temperature. The chamber has internal electric heaters for elevated
temperatures and uses external carbon dioxide gas as a coolant for reduced
temperatures.
Specimen Size:
A variety of specimen shapes can be used for this test, but the most
commonly used specimen size is 3.2mm x 12.7mm x 125mm (0.125" x
0.5" x 5.0") for ASTM, and 10mm x 4mm x 80mm for ISO.
Data:
Flexural strength, flexural stress at specified strain levels, and flexural
modulus can be calculated.
Mold Shrinkage - back
Mold shrinkage is the shrinkage of the polymer as it cools after the molding
process. It is typically used to properly machine injection molds so that
final part dimensions are as desired. Mold shrinkage can be dependant upon
the molding parameters used - often the extremes of the processing range for
the material plus a midrange value are tested.
Test Procedure:
The length or diameter of the cavity is measured depending on shape of mold.
Test specimens are molded under specified conditions. The parts cool and
after 48 hours, the molded parts are measured and the shrinkage is
calculated.
Specimen Size:
Enough resin to mold the required samples.
Data:
Mold shrinkage is calculated as inches per inch (or percent or mm per mm) for
the specified dimensions and conditions.
The Peel Test - back
The Peel Test measures the strength required to pull apart a bonded surface.
It is useful in evaluating adhesives, adhesive tapes, or other attachment
methods.
Test Procedure:
After the sample is measured for thickness, it is placed in a fixture in a
universal tester. The specimen is pulled at the specified speed until either
the part or the bond fails. Types of failure are noted as cohesive, adhesive,
or substrate failure.
Specimen Size:
Two 6 in. x 1 in. specimens are superimposed on one another and bonded by
adhesive, or other method, in the center.
Data:
Break type - cohesive, adhesive, or substrate. Peel strength.
Tensile Strength - back
Tensile tests measure the force required to break a specimen and the extent
to which the specimen stretches or elongates to that breaking point. Tensile
tests produce a stress-strain diagram, which is used to determine tensile
modulus. The data is often used to specify a material, to design parts to
withstand application force and as a quality control check of materials.
Since the physical properties of many materials (especially thermoplastics)
can vary depending on ambient temperature, it is sometimes appropriate to
test materials at temperatures that simulate the intended end use
environment.
Test Procedure:
Specimens are placed in the grips of the Instron at a specified grip separation
and pulled until failure. For ASTM D638 the test speed is determined by the
material specification. For ISO 527 the test speed is typically 5 or 50mm/min
for measuring strength and elongation and 1mm/min for measuring modulus. An
extensometer is used to determine elongation and tensile modulus.
Elevated or Reduced Temperature Test Procedure:
A thermal chamber is installed on the Instron universal test machine. The
chamber is designed to allow the test mounts from the base and crosshead of
the Instron to pass through the top and bottom of the chamber. Standard test
fixtures are installed inside the chamber, and testing is conducted inside
the controlled thermal environment the same as it would be at ambient
temperature. The chamber has internal electric heaters for elevated
temperatures and uses external carbon dioxide gas as a coolant for reduced
temperatures. The size of the chamber places a limitation on the maximum
elongation that can be reached, and extensometer are generally limited to no
more than 200° C.
Specimen Size:
The most common specimen for ASTM D638 is a Type I tensile bar. ASTM D882
uses strips cut from thin sheet or film.
Data:
The following calculations can be made from tensile test results:
1. tensile strength (at yield and at break)
2. tensile modulus
3. strain
4. elongation and percent elongation at yield
5. elongation and percent elongation at break
Equipment used at Plastics Technology Laboratories, Inc.:
Instron Universal Tester Extensometers
Surface Resistivity - back
Surface resistivity is the resistance to leakage current along the surface of
an insulating material. Volume resistivity is the resistance to leakage
current through the body of an insulating material. The higher the
surface/volume resistivity, the lower the leakage current and the less
conductive the material is.
Test Procedure:
A standard size specimen is placed between two electrodes. For sixty seconds,
a voltage is applied and the resistance is measured. Surface or volume
resistivity is calculated, and apparent value is given (60 seconds
electrification time).
Specimen Size:
A 4-inch disk is preferable, but may be any practical form, such as flat
plates, rods or tubes for insulation resistance.
Data:
Surface and Volume resistivity are calculated.
Surface Resistivity is expressed in ohms (per square)
Volume Resistivity is expressed in ohms - cm
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The Ownership and Management
Nexcycle Plastics Inc.
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