Detail of GB/T 42542-2023

Introduction of GB/T 42542-2023

GB/T 42542-2023 Fibre-reinforced composites - Method for accelerated moisture absorption and supersaturated conditioning by moisture using sealed pressure vessel 1 Scope This document specifies accelerated moisture absorption properties and supersaturated conditioning by moisture for fibre-reinforced plastics) using sealed pressure vessel at higher temperature than 100 °C with saturated water vapour at used heating temperature. The purpose of this moisture absorbing procedure is to screen test specimens with moisture by mechanical or thermal properties. This document applies to carbon-fibre materials and their products with either thermoset or thermoplastic matrices, with a Tg greater than 150 °C. This document can also apply to materials reinforced with other fibres (e.g. glass-fibres) with a Tg greater than 150 °C. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 472 Plastics - Vocabulary Note: GB/T 2035-2008, Terms and definitions for plastics (ISO 472:1999, IDT) 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 472 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: ——ISO Online browsing platform: available at https://www.iso.org/obp ——IEC Electropedia: available at http://www.electropedia.org/ 3.1 additional moisture content mass percentage of additionally absorbing moisture in the test material to total mass of the material and moisture already existing in this material Note: See Formula (1). 3.2 initial moisture content mass percentage of absorbed moisture in the test material at the initial time Note: See Formula (3). 3.3 supersaturated conditioning by moisture moisture absorbing conditions in the test material at room temperature cooled from the saturated moisture absorbing condition at higher temperature and higher humidity, such as saturated water vapour pressure at used higher temperature 3.4 accelerated moisture absorption moisture absorption by process with specific conditions such as higher temperature (e.g. 120 °C) and higher pressure of moisture (0.2 MPa) to obtain saturated moisture content (3.5) during shorter time 3.5 saturated moisture content moisture content from absorption condition with supersaturated moisture at lower temperature (e.g. room temperature) from higher temperature (e.g. 120 °C) where specimen has saturated moisture content 4 Principle To obtain almost similar saturated moisture condition in a test material at room temperature for shorter time, the test material absorbs moisture at higher temperature and higher humidity conditions such as 120 °C and 0.2 MPa of saturated water vapour pressure without air (oxygen) gas. Higher temperature causes higher diffusion rate of water molecules in materials and higher water vapour pressure causes higher frequencies of water molecules uptake at the surface of the material from outside. Therefore, equilibrium and saturated moisture condition to the materials is obtained during shorter time. However, if this material with saturated moisture is cooled to room temperature, this material absorbs supersaturated moisture because of slow diffusion rate inside of water molecules and slow releasing rate of water molecules at the surface. In this way, supersaturated moisture condition for thermoset and thermoplastic matrices is obtained. It is important that this procedure does not cause degradation of the test material. Mechanical properties should be monitored to be stable during repeating these absorbing and desorbing (drying) processes. In addition, this condition is simulated condition for real condition to obtain saturated equilibrium moisture content at room temperature. The purpose of this test method is to screen the optimal materials primarily during the research and development processes.

Contents of GB/T 42542-2023