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In this paper, we demonstrate the effects of radiation exposures of polymeric materials with UV-A 340 nm lamps (ISO 4892-3, Type 1A) at -10 °C in comparison to an irradiation at +50 °C using a Global UV Test 200 fluorescent lamp device from Weiss Umwelttechnik GmbH, which incorporates an active cooling appliance. While the effects at -10 °C actually are lower than at + 50°C their extent was clearly beyond expectations.
The individual and collective impacts of additives in melt dripping behaviour were studied under UL 94 vertical test conditions. A set of polyamide 6 (PA6) based materials compounded with melamine cyanurate (MCA) – a ˝dripping agent˝ – and glass fibre (GF) – a ˝non-dripping agent˝ - was investigated in detail. Dripping quantification was carried out during first and second ignition. The materials and their drops were investigated with respect to thermal decomposition, melt viscosity, and others properties. PA6 with V-2 classification improves to V-0 when MCA is added; and is worsened to HB in presence of glass fibre. Together, PA6/GF/MCA achieved V-2. The non-flaming drops of PA6/MCA are formed by oligomeric fragments. The flaming drops of PA6/GF contain a high amount of glass fibre. The dripping behaviour of PA6/GF/MCA under fire is a complex response of the specimen, but not explained by an easy superposition of the materials’ properties. The dripping behaviour is influenced by the interaction and concurrence of the different phenomena.
Thermal and corrosion (in)stability of polyamide 6 studied by broadbend dielectric spectroscopy
(2015)
The thermal and corrosion (in)stability of polyamide 6 (PA6) is investigated by dielectric spectroscopy. The dielectric spectra can be decomposed into two local relaxation modes, two segmental modes and a high temperature conductivity/Maxwell-Wagner-Sillars process assigned to the blocking of charge carriers at interfaces between amorphous and crystalline phases of PA6. After thermal testing, the PA6 sample shows no changes in the dielectric spectra. However, after the corrosion test two main changes are observed: (1) A higher activation energy for the local β-relaxation process and (2) an increased intensity of the MWS/conductivity process which is shifted to lower temperatures. It is argued that the changes in the dielectric spectra are caused by remaining salt ions in the sample. A comparative study with non-polar polyethylene reveals that the incorporation of the salt ions during the corrosion test can be traced back to the polarity of PA6.