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üDC 678.5/8 : 620.1 13
IS0
I NTERN AT1 ON A L ORGAN IZATl ON FOR STA N DARD IZATION
IS0 RECOMMENDATION
R 870
P LAST I CS
PREPARATION OF SPECIMENS
FOR OPTICAL TESTS ON PLASTICS MATERIALS
CASTING METHOD
1st EDITION
November 1968
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Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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ISO/R 870-1968 (E
I SO Recommendation R 870 November 1968
P LAST I CS
PREPARATION OF SPECIMENS
FOR OPTICAL TESTS ON PLASTICS MATERIALS
CASTING METHOD
1. SCOPE
This IS0 Recommendation describes a method for casting plastics specimens for optical tests.
NOTE. ~ The preparation of specimens for optical tests by moulding is the subject of IS0 Recommendation R 869. Plastics
Preparation of specimens for optical tests on plastics materials -- Moulding method.
2. APPARATUS
The type of mould recommended is shown in the Figure below. It consists of the following parts :
two plates of glass with plane surfaces at least as good as those of photographic plates; a borosilicate glass
(U)
resistant to thermal shock is recommended;
a stainless steel spacer about 4 mm thick;
(b)
a gasket of greater thickness than the spacer; the material used to make the gasket depends on the type of
(c)
plastics material to be cast. In any case it should be of sufficient elasticity to compensate for the
shrinkage of the plastics material;
two G-clamps to hold the plates together;
(d)
two plates, of metal or other rigid material, to be placed on either side of the glass plates to distribute the
(e)
clamping pressure.
Plastics material
Stainless steel spacer
f
Clamping plates
FIGURE - Mould for the preparation of test specimens for optical tests
-2
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ISO/R 870-1968 (E
3. PROCEDURE
After cleaning the plates carefully, assemble the apparatus as shown in the Figure.
3. I
Mix the plastics material with the appropriate types and quantities of accelerator and catalyst, or cross-
3.2
linking agent.
3.3 Pour the plastics material into the mould; then gradually heat the mould at a temperature and for a time
which is dependent on the type of plastics material being cast. If necessary, air in the mould may be
evacuated to minimize the formation of bubbles in the specimen.
3.4 Then
...