Correlation between Impact Strengths Measured on the Basis of Various Standards for Rigid PVC Plates

The Charpy method and the Izod method are usually applied to test of impact strength of rigid PVC plate. There are some differences between various standards on shapes and dimension of the Charpy impact test specimens. Ten kinds of rigid PVC plates have been tested according to the JIS, the ISO and the ASTM Charpy impact testing methods, and also to the ASTM Izod impact testing method. The results obtained are summarized as follows:(1) JIS Charpy impact strengths (JIS·akC) of the test plates take the values from 2.3 to 8.4kg-cm/cm2.(2) ISO Charpy impact strengths (ISO·akC) of the test plates, except an extruded one, take roughly a constant value i.e. 2.5kg-cm/cm2.(3) ASTM Charpy impact strengths and ASTM Izod impact strengths show similar characteristics. Their characteristics are both divided into two groups, i.e. ductile group (JIS·akC>5kg-cm/cm2) and brittle group (JIS·akC<5kg-cm/cm2). The characteristics of ductile and brittle groups are similar to those of JIS·akC and ISO·akC respectively.(4) The above mentioned phenomenon is caused mainly by the difference of notch depth.(5) There are approximately linear relationships between various impact strengths except a few values. The regression lines shown in Table IV can be used for conversion of an impact strength into another one.