A speck will ultimately cause a failure to occur by virtue of its appearance in a film or by the decrease in electrical or mechanical properties in the polymer substrate (see Specification D1248).

The analysis of composite layers for barrier purposes by microscopic Fourier transform infrared spectroscopy (FT-IR) can indicate the adequacy of the barrier tape or indicate why a barrier may be defective (a missing layer or hole in the layer or poor coextrusion practice). Fig. 1 represents a typical multilayer film.

FIG. 1 Position and Function of Materials in Typical Multilayer Films

1.1 This practice describes the techniques used for detecting two different polymer entities as follows:

1.1.1 Abnormal specks or spots on a surface or in the film that are objectionable as defects and

1.1.2 Layers of different polymeric sheets commonly used as barrier films made by coextrusion.

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 7.

Note 1—There is no known ISO equivalent to this standard.