The color-changing effect during thermally stimulated shrinkage of a combined package of metallized, heat-shrinkable, and biaxially oriented films made of thermoplastic polymers has been studied. The color-changing effect occurs and can only be detected in polarized light. In the absence of light polarization, the package of linearly oriented heat-shrinkable and biaxially oriented dichroic films is transparent and colorless, and the metallized film layer is monochrome. It has been experimentally established that in the process of thermally stimulated shrinkage of a transparent linearly oriented polyvinyl chloride film with dichroism, the transmission coefficient of ordinary and polarized light differs significantly, depending on the wavelength of the light and the level of internal stresses in the film. It is proposed to use this difference in the manufacture of an innovative indicator of the insulation quality of electrical contacts. In electrical engineering, there is a need to "smooth out" the surges of electric field strength in the area of cable connection and reduce the complexity of the assembly of a bundle of wires. Many patented technical solutions combining the use of mechanochromic polymer composites and electronic devices have been devoted to the development of indicators and methods for indicating (visualizing) compressive stresses in the field of wire connection. The present study shows the possibility of visual indication of internal stresses compressing contacts by the color of multilayer insulation made of metallized, heat-shrinkable and biaxially oriented films in polarized light. Polarized light reflected from the mirror surface of the metallized film causes the pleochroism effect (the appearance of bright color) due to the interference of electromagnetic waves on thin transparent polymer films that make up the "insulation package" with a stepped layer. The stepped layer is formed by spiral overlapping of a dichroic biaxially oriented polypropylene film. The article shows the product result of optical research and provides an example of the practical use of heat-shrinkable polymer materials in electrical engineering. According to the reflection spectra of polarized light, the variable color of multilayer insulation with an upper layer of a polyvinyl chloride film of domestic production is quantitatively characterized.)

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