Research on the mechanical properties of glass fiber reinforced composite materials at high temperatures: the fiber layer structure has a significant impact, with a 80% drop in compressive strength at 100 ° C

Research Background and Testing Plan: A study published in Fire and Materials focuses on the mechanical properties of vacuum infused glass fiber reinforced polymer (GFRP) composites at high temperatures, with a particular emphasis on the influence of fiber architecture. The research team prepared laminates with three fiber configurations: unidirectional (UD), bidirectional 0 °/90 ° orthogonal layup (BD), and ± 45 ° off-axis angle layup (OA), and conducted tensile and compression tests at multiple temperature points up to 300 ° C under steady-state conditions. The test results were also jointly analyzed with data from previous multi axial (MA) fiber laminates.

Key data: The matrix dominant performance is more sensitive to temperature

Research has confirmed that the mechanical properties of GFRP have significant temperature dependence, with the matrix dominant performance being more significantly affected.

. At 100 ° C, due to the glass transition, there is a significant decrease in compressive strength, with a decrease of about 80%, especially in the unidirectional configuration. In contrast, the decrease in tensile strength and tensile and compressive moduli dominated by fibers is relatively small, with unidirectional configurations of about 10%, 20%, and 10%, respectively. For multi axial fiber structures, their behavior is between unidirectional and bidirectional orthogonal layup, further highlighting the influence of fiber layup structure on high-temperature performance. The study also evaluated the simulation ability of the empirical models and phenomenological analysis models proposed in the literature on the experimental results, and the overall fit was good. Finally, the experimental data was compared with the design oriented temperature conversion factor proposed by CEN/TS 19101:2022, and the results showed that this factor can still provide reasonable performance reduction when the fiber volume fraction in the load direction is as low as 20%.

The significance of polymer additives and building materials industry

Although this study did not directly involve the formulation of polymer additives, it revealed the law of rapid deterioration of matrix dominant properties near the glass transition, which has direct reference value for the weather stability design of composite materials and polymer materials for construction and home decoration.

. GFRP may experience long-term temperature fluctuations in building structures, exterior wall panels, door and window profiles, and the significant reduction in compression performance suggests that the relationship between the thermal transition temperature of the matrix resin and the operating temperature range should be fully considered in design. From the perspective of material modification, improving the heat resistance and long-term stability of the matrix resin often requires the use of antioxidants and light stabilizers to delay thermal oxidative aging and UV aging, which is consistent with the weather resistance and stability strategies widely used in building materials such as PVC profiles. For glass fiber reinforced systems, the glass transition temperature of the matrix resin, curing system, and interfacial properties jointly determine the load-bearing capacity at high temperatures; In outdoor exposure environments, the reasonable combination of light stabilizers and antioxidants helps to maintain matrix properties, slow down brittleness and strength loss caused by aging. The vacuum infusion process used in the study also suggests that the influence of processing technology on fiber infiltration and porosity will be indirectly reflected in the high-temperature mechanical performance. In addition, the temperature conversion factor of CEN/TS 19101:2022 still performs reasonably at lower fiber volume fractions, providing a standardized reference for reducing material properties based on temperature in engineering design. For composite components in the fields of architecture and home decoration, combining weather resistant and stable additive systems with standardized temperature reduction methods is expected to optimize material selection while ensuring safety margins. It should be noted that this study is a laboratory steady-state condition test, and the long-term performance of actual building components is also affected by factors such as wet heat cycles, load duration, and ultraviolet radiation. Therefore, extrapolation of relevant conclusions should be cautious.

Information source:Mechanical Behaviour of Vacuum‐Infused GFRP Composites at Elevated Temperatures—Influence of Fibre Architecture， Organized by Herun Chemical.