IS 13360-9-8: Plastics - Methods of Testing, Part 9: Optical Properties, Section 8: Determination of Transparency of Plastic Sheeting

8 Pages·2001·1 MB·English

by  Bureau of Indian Standards

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IS 13360-9-8 (2001): Plastics - Methods of Testing, Part 9:
Optical Properties, Section 8: Determination of
Transparency of Plastic Sheeting [PCD 12: Plastics]
“!ान $ एक न’ भारत का +नम-ण”
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“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै”
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IS 13360 (Part 9/See 8) :2001

Indian Standard
PLASTICS — METHODS OF TESTING
PART 9 OPTICAL PROPERTIES
Section 8 Determination ofTransparency of
Plastic Sheeting
ICS 83.140,10

@ BIS 2001
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
January 2001 Price Group 1
Methods of Test for Plastics Sectional Committee, PCD 23
FOREWORD
This Indian Standard (Part 9/See 8) was adopted by the Bureau of Indian Standards, after the draft finalized
by the Methods of Test for Plastics Sectional Committee had been approved by the Petroleum, Coal and
Related Products Division Council.
The attribute of clarity of a sheet, measured by its ability to transmit image-forming light, correlates with its
regular transmittance. Sensitivity to ditTerencesfiproves with decreasing incident beam- and receptor-angle.
If the angular width of the incident beam and of the receptor aperture (as seen from the specimen position)
are of the order of0.1° or less, sheeting ofcommercial interest have a range oftransparency of about 10to 90
percent as measured by the method specified in this standard, Results obtained by the use of this test method
are greatly influenced by the design parameters of the instruments; for example, the resolution is largely
determined by the angular width ofthe receptor aperture. Caution should therefore be exercised in comparing
results obtained from different instruments, especially for samples with low regular transmittance.
Regular transmittance data according to the test method prescribed in this standard correlate with the
property commonly known as ‘see-through’, which israted subjectivelybythe effectof ahand-held specimen
on an obsemer’s ability to distinguish clearly a relatively distant target. This correlation is poor for hi@ly
diffhsing materials because of interference of scattered light in the visual test.
While preparing this standard considerable assistance hasbeen derived from ASTM D 1746-92 ‘Standard test
method for transparency of plastic sheeting’ issued by American Societyfor Testing and Materials (ASTM),
USA.
In reporting the results of atest or analysis made in accordance with this standard, ifthe final value, observed
or calculated, is to be rounded off, it shall be done in accordance with IS 2:1960 ‘Rules for rounding off
numerical values (revised’.
IS 13360 (Part 9/See 8) :2001
Indian Standard
PLASTICS — METHODS OF TESTING
PART 9 OPTICAL PROPERTIES
Section 8 Determination ofTransparency of
Plastic Sheeting
1 SCOPE 4.1.1 An incandescent or vapour-arc lamP, with a
regulated power supply such &at fluctuations in light —.....—
This standard (Part 9/See 8) prescribes the method
intensity shall be lessthan *1 percent. If an arc lamp
for the measurement of the transparency of plastic
is * an appropriate filter shall be used to limit
sheeting in terms of regular transmittance (T,).
light only to the spectml range from 540 to 560 nm.
Although generally applicable to any translucent or
transparent material, it is principally intended for us 4.1.2 A sy$em of apertures and lenses shall be used
with nominally clear and colorless thin sheeting. that willprovide a symmetrical incident beam. When
measured with the indicating or recording system of
2 REFERENCE
the apparatus, using a receptor aperiure having a
The following standard contains provisions which width or diameter subtending an angle of 0.025 *
through referenee in this tem constitutes provisions 0.005° at the plane of the specimen, the incident
ofthis standard. Atthe time ofpublication the edition beam shall meet the following requirements:
indicated was valid. All standards are subjeet to
Angle, A4dximumRelative
revisions, and parties to agreements based on this
Degree Intensity
standard are encouraged to investigate the possibility
o 100
of applying the most recent edition of the standard
0.05 10
indicated below:
0.1 1
ISNo. i“itle
0.3 0.1
“IS 13360 (part 9/ Plastics —Methods oftesting:
The source aperture may be circular or a rectangular
Sec5) :1999 Part 9 Optical properties, See-
slit having a length-to-width ratio of at least 10.
tion 5 Determination of haze
4.1.3 A holder shall be provided that will seeure the
and luminous transmittance of
specimen sothat itsplane isnormal to the axis ofthe
tmnspamnt plastics
incident beam at a fixed distance from the receptor

3 TERMINOLOGY
aperture. Provision must be made for rotating the

3.1 Defhitions specimen if slit optics are used. Provision for
transverse motion may be provided to facilitate
3.1.1 Transmittance
replication of measurements.
Theratioofthe flux transmitted bya specimen tothe 4.L4 An aperture shall be provided over the receptor
radiant flux incident on the speeimen. so that its diameter or width subtends an angle, at
theplane ofthe specimen, of0.1 * 0.025°. The image
3.1.2 Regular Transmittance
of the source aperture with no specimen in place
The ratio of undifhsed transmitted flux to incident shall be the same shape as the receptor aperture
flux. The regular transmittance may equal the total centered on and entirely within it.
transmittance but earmot exceed it. (For this test
4.1.5 Aphotoelectric detector shall be provided such
meth~ limitations on the geometry of the optical
that the indicated or recorded response to incident
system are specified in 4).
light shall be substantially a linear function and
4 APPARATUS uniform over the entire range from the unobstructed
&am (1) to 0.0110 or less.
4.1 The apparatus shall consist of a light source,
sourceaperture, lenssystem specimenholder,remptor 4.1.6 Meansshallbeprovided for relatively displacing,
aperture, photoelectric detector, and an indicating or the receptor or the image of the source aperture (in
recording system, arranged to measure regular the plane ofthe receptor aperture) by at least 1°from
transmittance. The system shall meet the following the optical axis of the undeviated incident beam; for
requirements. circular apertures, in two directions at right angles to

1
IS 13360 (Part 9/See 8) :2001
each othe~ for slit optics, in the dirwtion of the 8.1 Turn the instrument on and allow it to come to a
short dimension of the slit. stable operating temperature.
NCYIWS 8.2 Whh the light beam blocked at sample positioq
set the reading to zero.
1 ‘ririsprovisi onisneceaaq forchecking the geanetry ofthe
incident beam (4.1.2) and for readjusting for maximum tight
8.3 Whhthe light beam unblock@ adjust the reading
intensity intheeventttratthebeamis&via!A byaspecimen wittr
nonparallel surfii. to a maximum by moving the receptor aperture so
that the r-ptor receivesthe maximum intensity from
2 Appamtus m=ting these requirements b beendmmibed in
the light. Either set this value to 100 or record it as
theliterature,andcommercial vemimrsareavailable.
1
5 REFERENCE MATERIALS 0“
8.4 Checkfor changes in instrument performance by
5.1 Since no regular transmittance standards are
reading the reference materials prepared in 5.
known to be available, it is recommended that
specimens of glass or other material believed to 9 PROCEDURE
maintain constant light transmission properties with
9.1Turn the instrument on and allow it to come to a
time be selected that yield different regular
stable operating temperature.
transmittance values for use as reference materials.
9.2 Wh.hthe light beam blocked at sample Positiow
5.2 Measure the regular transmitt+xe value of each
set the reading to zero.
specimen, and label it with the value obtained.
9.3 Withthe light beam unblocked, set the reading to
5.3 Keep these reference materiah for checking for
100and record it as 10.
changes in instrument performance in the future.
9,4 Mount a test specimen in the instnunent so that
6 TEST SPECIMENS
it is neither wrinkled nor stretched but centered and
6.1 All specimens shall be nominally colorless (see normal to the light beam. Record the reading as l~.
Note) and transparent to translucent have essentially
10 CALCULATION
plane parallel surfaces, and tx+free of surface or
internal contamination. Calculate the percent regular transmittance, T, as
follows:
NOrE —Transparencyofcolouredorhighlyreflectivematerials
may be measured by the ratio of T/Tt, where 7’,is the total T,= 100Ir110
luminous transmittance [see 1S13360 (Psrl 9/See 5)].
where
6.2 Nonrigid specimens shall be held in a suitable
holdersothattheyareflatandfreefromwrinkles. 1, = light intensity with the specimen inthe beam,
and
7 CONDITIONING

10= light intensity with no specimen in the beam.
7.1Conditioning

NOTE — No calculation is needed if Io is set to 100 or a
Condition the test specimens at 27 * 2°C and 65 * 5
convemionchartorspeciatacateisusedtointqret theimlrument
percent relative humidity for not less than 40 h prior reading
to test those tests where conditioning is required. In
11REPORT
cases of disagreement, the tolerances shall be *l°C
and H percent relative humidity. Report the following information:
7.2 Test Conditions a) Sample designation%
b) Instrument used,
Conduct tests in the standard Iaboratow atmosphere
of 27 * 2°C and 65 * 5 percent relative humidity, c) Average regular transmittance,
unless otherwise specified in the test methods. In d) Number of specimens test@
cases of disagreement, the tolerances shall be *l°C
e) Standard deviation, and
and M?percent relative humidity.
o Any measured anisotropy.
8 INSTRUMENT ADJUSTMENT

2
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Amendments areissued to standards asthe need arises onthebasis ofcomments. Standards arealso reviewed
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needed; ifthe review indicates that changes areneeded, it istaken up forrevision. Users ofIndian Standards
should ascertain that they are inpossession ofthe latest amendments oredition byreferring to the latest issue
of’BIS Handbook’ and’ Standards: Monthly Additions’.
This Indian Standard has been developed from Dot: No. PCD 23 (1680).
Amendments Issued Since Publication
AmendNo. DateofIssue TextAffected
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