EuroWire January 2023

Technology News

Avoiding degradation of polymers and discolouration of cables in outdoor conditions

Combinations of these two additive families are also used. The addition of anti-oxidant additives is also common to avoid polymer degradation due to thermal stress. Thirdly, the process can be stopped by using carbon black, which achieves a high rate of ultraviolet radiation absorption. The advantage of carbon black is that it captures the energy and prevents it from reacting with the polymer. The most effective carbon blacks are those with the smallest particle size, as they present a greater surface to trap solar radiation. There is no additive that protects the colour of the cable as it does the polymer. The solution is to formulate the colour using pigments prepared to withstand outdoor conditions. An in-depth study of the behaviour of the pigments in the different types of polymers used in the cable industry (PVC, HFFR, TPU, XLPE, EPDM, etc) under outdoor conditions is required. Having this in-depth knowledge can ensure the stability of the cable colour over its useful life outdoors. Delta Tecnic https://deltatecnic.com

withstand photodegradation. Industries that operate with medium voltage cables, photovoltaic cables for solar panels, power cables for buildings or fibre optic cables seek to avoid this cumulative and irreversible process. Ultraviolet radiation (UV) causes photo oxidative degradation that leads to breakage of polymer cables. This generates free radicals, which start off a chain reaction resulting in the degradation of the visual appearance of the cable, its shine and its surface, as well as its mechanical properties, all limiting its useful life. There are three strategies for mitigating polymer photodegradation. The first involves using UV filter additives, which have the ability to absorb ultraviolet light. When sunlight comes into contact with these additives, they react and prevent the light from reaching the polymer. The second method uses HALS (hindered amine light stabilisers) – additives that react to free radicals, blocking them and avoiding breakdown of the polymer chains. When ultraviolet light strikes and free radicals are generated, the HALS act to stop the degradation process. For X-ray measuring in single-layer applications, Sikora has developed the X-Ray 6000 Pure. The new 6070 and 6120 models are available for measuring tubes and hoses from 6 to 65mm and 10 to 110mm, respectively. In addition to single-layer tubes and hoses, the total wall thickness of many multi-layer products can be measured. In combination with the Ecocontrol Pure, a processor system with a high-resolution 15" touchscreen display, the measured values are clearly displayed for further analysis. The X-Ray 6000 Pure is a safe and power ful alternative to conventional measuring technologies. The system allows users to constantly monitor wall thickness and to reduce it to the minimum tolerance val ue. Safety margins can be reduced, and the automatic control keeps the dimen sions within the specification.

Outdoor cables suffer the consequences of conditions such as light exposure, changes in temperature and humidity. As well as discolouration, the polymers can lose their mechanical properties. The effects can be summarised into two concepts: lightfastness, which covers exposure to light, and weathering, which includes factors such as temperature and humidity. It is necessary to distinguish between these when looking for solutions, as pigments that offer good lightfastness might not work adequately at different temperature ranges or levels of solar radiation. The behaviour of pigments outdoors can be measured with a test that accelerates the state of exposure of plastics under different sunlight, temperature and humidity conditions. This facilitates the selection of pigments and, therefore, the prediction of the life expectancy of the cable. Installations dedicated to energy or wire- less networks require a cable designed to

Quality control in extrusion lines with X-ray technology

For measuring up to three layers, Sikora also offers the X-Ray 6000 Pro. Sikora AG www.sikora.net

The new X-Ray 6000 Pure for single-layer measurement

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January 2023