(ISo 458/2 International Standard INTE RNATIONAL ORGANIZATION FOR STANDARDIZATION MEXAYHAPOAHAR OPFAHM3ALMA nO CTAHAAPTW3ALWM+ORGANISATION INTE RNATIONALE DE NORMALISATION Plastics - Determination of stiffness in torsion of flexible materials Part 2 : Application to plasticized compounds of homopolymers and copolymers of vinyl chloride Plastiques - Détermination de la rigidite en torsion des plastiques souples - Partie 2 : Application aux compositions plastifiees d'homopolymeres et de copolymeres de chlorure de vinyle First edition - 1985-04-01 $0 458/2-1985 (E) UDC 678.743.22 : 620.175.251 Ref. No. ISO 458/2-1985 (E) Descriptors : plastics, vinyl chloride, tests, torsion tests, determination, torsion angle, rigidity, test equipment. Price based on 2 pages Not for Resale Foreword 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 feast 75 % approval by the member bodies voting. International Standard ISO 458/2 was prepared by Technical Committee ISO/TC 61, Plastics, International Standards ISO 458/1 and ISO 458/2 cancel and replace ISO Recommen- dation R 458-1965, of which they constitute a technical revision. International Organization for Standardization, 1985 ? Printed in Switzerland No reproduction or networking permitted without license from IHS Not for Resale ISO 458/2-1985 (E) INTERNATIONAL STANDARD Plastics - Determination of stiffness in torsion of flexible materials . Part 2 : Application to plasticized compounds of homopolymers and copolymers of vinyl chloride Introduction 0 Scope and field of application In the case of compositions based on plasticized polyvinyl This part of ISO 458 specifies a method for determining the chloride, all the curves for the logarithm of the stiffness in tor- temperatures corresponding to three conventional sion as a function of temperature have a similar appearance, in characteristic values for the stiffness in torsion of plasticized the form of a reversed S. Each curve is essentially characterized compounds of homopolymers and copolymers of vinyi by three regions : chloride. a) two extreme regions, where the change in the stiffness Reference as a function of temperature occurs relatively slowly : Iso 458/1, Plastics --- Determination of stiffness in torsion of 1) a region of elevated values, corresponding to a high flexible materials - Part 1 : General method. degree of rigidity, attributed by some authors to a loss of elastic properties. The value of the stiffness in torsion Principle was taken arbitrarily by Clash and Berg[1l as 3 3,1 × 109 dyn/cm2*, Use of Iso 458/1 for plasticized compounds of homopolymers and copolymers of vinyl chloride, consisting of determining, ac- 2) a region of low values, corresponding to a high degree of flexibility. In this case the corresponding stiff- cording to a special case of method A with an angle of deflec- tion between 55° and 650, the temperatures corresponding to been arbitrarily intorsionhas taken ness as three characteristic values of the stiffness in torsion (T), i.e. : 42 kgf/cm2** representing an appropriate value for films 300 MPa, 23 MPa and 4 MPa. having a sufficient degree of flexibility at normal use temperature to render them suitable for the production Equipment of curtains, drapes and waterproof materials; 4 b) an intermediate region where the change in the stiff. See ISO 458/1. ness is generally more rapid and where the curve exhibits an inflection. This region has been arbitrarily allotted the value 5 Te