ASTM D3351-93
(Test Method)Standard Test Method for Gel Count of Plastic Film (Withdrawn 2000)
Standard Test Method for Gel Count of Plastic Film (Withdrawn 2000)
SCOPE
1.1 This test method covers the determination of the number of gels present in plastic film when observing the images formed on a screen when light is projected through the film.
1.2 The thickness of the films covered by this specification is 100 [mu]m (0.004 in.) or less.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Note 1-There is no similar or equivalent ISO standard.
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Designation: D 3351 – 93
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Gel Count of Plastic Film
This standard is issued under the fixed designation D 3351; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 5.1.1 A rectangle 190 by 200 mm (7 ⁄2 by 8 in.) shall be
drawn on the viewing plate of the projector.
1.1 This test method covers the determination of the number
5.2 Projection Screen, at least 2 by2m(6by6ft) in size.
of gels present in plastic film when observing the images
5.3 Acrylic Plate, approximately 230 by 230 mm (9 by 9 in.)
formed on a screen when light is projected through the film.
by 3.2 mm (0.125 in.) thick containing two standard holes, one
1.2 The thickness of the films covered by this specification
of which is 0.80 mm ( ⁄32 in.) in diameter and the other is 0.40
is 100 μm (0.004 in.) or less.
mm ( ⁄64 in.) in diameter. The holes shall be approximately 1
1.3 This standard does not purport to address all of the
mm deep and shall have smooth edges. They shall be approxi-
safety problems, if any, associated with its use. It is the
mately 12 mm apart, and roughly centered on the acrylic plate.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
6. Test Specimens
bility of regulatory limitations prior to use.
6.1 A test specimen consists of four layers of film which are
NOTE 1—There is no similar or equivalent ISO standard.
at least 200 mm (8 in.) square. A convenient size is 254 mm (10
in.) square. It is also convenient to staple the four layers
2. Terminology
together at one corner.
2.1 Definitions:
6.2 Three test specimens shall be prepared for testing.
2.1.1 gel—a nodule of plastic material which is present in
6.3 An area 190 by 200 mm (7 ⁄2 by 8 in.) is viewed through
the matrix of film and is of such a composition that it is not
four layers of film, which gives a total film test area of 1520
readily blended with the matrix. Gels are believed to be 2
cm (240 in. ).
composed of oxidized or high molecular weight materials, or
both. A gel is to be distinguished from contamination such as
7. Preparation of Apparatus
particles of dirt, carbon, or lint.
7.1 Set up the projector and screen so that a magnification of
between 8 to 1 and 10 to 1 is obtained. Care should be taken in
3. Summary of Test Method
projection not to distort the image on the screen. To prevent
3.1 This test method was developed because the counting of
distortion, the line of projection from the mirror to the screen
gels in plastic film with the unaided eye is difficult and
should be perpendicular to the screen.
fatiguing to the operator. The test method calls for magnifying
the specimen by about 8 to 1, thus making the gels easier to
8. Conditioning
see. At the same time, standard-size images are projected on
8.1 No specific conditioning period is required.
the screen at the same magnification.
9. Procedure
4. Significance and Use
9.1 Place two blown tubing specimens or four flat film
4.1 The presence of gels in plastic film is often objection-
specimens, four layers of film in each case, on top of each other
able due to appearance and to the problems associated with
on the viewing plate of the projector, so that the lines on the
printing the film. This test method is designed to allow gels to
viewing plate include the center portion of each specimen.
be c
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