ASTM D882 Tensile Strength Properties of Thin Plastic Film by ADMET
One of the most common specifications that our customers follow is ASTM D882
which is the Standard Test Method for Tensile Properties of Thin Plastic Sheeting.
This test is very similar to the common ASTM D638 test whereby plastic material
is pulled until in breaks in order to measure elongation, tensile modulus, tensile
yield strength, and tensile strength at break. However, it is designed specifically
for thin sheeting and film less than 1 mm (0.04") thick.
The nice part about ASTM D882 is that the specimens are rectangular strips
of film and are not "dumbbell" or "dog bone" shaped. The
flat geometry of the specimens and the typical characteristic of films having
high elongation allow most users to avoid using an extensometer which allows
them to reduce the cost of the testing system and simplifies their testing regimen.
The two main things to keep in mind in regards to equipment are the height
of the testing machine and having grips designed to hold the thin film correctly.
We always recommend ADMET
eXpert 7601single column test machine with 29" of crosshead travel for
films with less than 300% elongation and our 53" model for really high
elongation films that elongate up to 900%. The grips we recommend are pneumatic
vise grips with rubber coated inserts. The rubber coated inserts help to keep
the film from prematurely breaking at the grip edge, and in combination with
the constant pneumatic pressure the film is prevented from slipping out of the
grips during the test. We use foot pedals to allow the operator to open and
close the grips with their feet because thin films usually require both hands
to line everything up properly. If you have a 30" crosshead travel machine,
the grips and load cell will take up about 12" of that travel. If you use
a 4" gage length it will take up another 4" of the travel. This leaves
14" of testing travel which will be fine for materials with less than 350%
elongation (14" crosshead travel / 4" original gage length = 3.5 *
100% = 350%) A 54" crosshead travel machine is better suited for materials
that have elongation up to 950%.
Run time: 2.13 mins