4897 TSO International Standard INTFRNATIONAL ORGANIZATION FOR STANDARDIZATION·MEKAYHAPOHAA OPTAHW3ALMA HO CTAHAAPTV3AUWM·ORGANISATION INTERNATIONALE DENORMALISATION Cellular plastics - Determination of the coefficient of linear thermal expansion of rigid materials at sub-ambient temperatures Determination du coefficient de dilatation lineique thermique des plastiques alveolaires rigides Plastiques alveolaires auxtemperaturesinférieuresaI'ambiante First edition -- 1985-04-01 UDC 678-405.8 : 536.413.2 Ref. No. ISO 4897-1985 (E) S0 4897-1985 (E) Descriptors : plastics, cellular plastics, tests, determination, thermal expansion, test equipment. Price based on 9 pages CopyrightInternational Organization for Standardization Not for Resale Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (Iso member bodies). The work of preparing International Standards is normally carried out through Iso technical committees. Each member body interested in'a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the Iso Council. They are approved in accordance with IsO procedures requiring at 5 % approval by the member bodies voting. least 75 International Standard ISO 4897 was prepared by Technical Committee ISO/TC 61, Plastics. ? International Organization for. Standardization,1985 Printed inSwitzerland Copyight International Organizatinfor Standardization ited without license from IHS Not for Resale ISO 4897-1985(E) INTERNATIONAL STANDARD Cellular plastics - Determination of the coefficient of linear thermal expansion of rigid materials at sub-ambient temperatures Scope and field of application Method A 1 4 This International Standard specifies two methods for deter- 4.1 Apparatus mining the coefficient of linear thermal expansion of rigid cellular plastics. at sub-ambient temperatures. Method A is the An apparatus found suitable consists of the following : preferred method since it gives a value on a large sample at a chosen temperature which is more representative because of anisotropy, etc., of the material or product. In practice, dif- 4.1.1 Test chamber and cooling system uniformity of the low temperature inside the. test chamber at The test chamber shall consist of a well-insulated box of ap- temperatures below -70 oc. Should this be the case, proximate internal dimensions 400 mm × 1 000 mm × 150 mm, Method B should be employed to obtain an "average" coeffi- having viewing windows 900 ± 10 mm apart. These windows cient for the temperature interval: between the cryogenic shall be insulated with plugs of insulation between readings to temperature and the ambient temperature. ensure good temperature distribution. The chamber shall be fitted with a cooling system designed to The values obtained in these tests are valid measurements only for the specific sample tested, at the time tested. They cannot give a sub-ambient internal temperature distribution complying with the requirements of 4.4. A suitable chamber and cooling be applied generally to a product and cannot be used to predict performance of the same material at a future date. system is described in the annex and illustrated in figures 1 and 2. Care should also be taken in applying the value obtained in this NOTE Liquid nitrogeni has been found in practice to be the most test to calculate the overall coefficient of expansion of com- satisfactory coolant. posite products of which the material under test is part. 4.1.2 Reference length material Many rigid cellular products are not isotropic. This is usually ascribed to-the fact that the cells in the material are elongated in Insid