Influence of Thermo-Oxidative Ageing on the Thermal and Dynamical Mechanical Properties of Long Glass Fibre-Reinforced Poly(Butylene Terephthalate) Composites Filled with DOPO

Abstract

In this work, the long glass fibre-reinforced poly(butylene terephthalate) (PBT) composites filled with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were prepared by melt blending, and the influence of thermo-oxidative ageing on the static and dynamic mechanical properties, thermal behaviours and morphology of composites with different ageing time at 120 °C were investigated and analysed. The results showed that the mechanical properties decreased in the primary stage of ageing, while embrittlement occurs in the later period, and the crystallinity of PBT decreases first, and then recovers to some extent. The scanning electron microscopy (SEM) photos of the samples indicated that the obvious crack appeared on the sample surface and a deeper, broader crack occurred with a longer ageing time. The results of energy dispersive X-ray analysis (EDAX) proved the DOPO filler diffused to the sample surface by measuring the content of phosphorus. Thermal gravimetric analysis (TGA) curves showed that the thermal stabilities of composites increased with longer ageing time, as did the values of the limited oxygen index (LOI). Meanwhile, the results of dynamic mechanical analysis (DMA) indicated that the glass transition temperature shifted to a higher temperature after ageing due to the effect of crosslinking, and both the crosslinking and degradation of PBT molecular chains act as the main factors in the whole process of thermo-oxidative ageing.

Sustainable biocarbon as an alternative of traditional fillers for poly(butylene terephthalate)‐based composites: Thermo‐oxidative aging and durability

“…The intensity of the aging conditions had a great influence on the mechanical properties of the composites. It has been reported that the tensile strength of long GF‐reinforced PBT with the addition of phosphorus‐based additive, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide reduced in the beginning of the thermal‐oxidative aging process (10–40 days) and increased later on in the process (50–60 days). In another study on the thermo‐oxidative aging effect on mechanical properties of short CF /PA6 composites, the tensile strength of the CF /PA6 composites increased at the initial stage of aging (from 200 to 800 h of aging) and started to decrease thereafter.…”

“…This showed that the heat aging process damages the PBT structures and causes embrittlement within the composites. The reduction in the mechanical properties was mainly due to the degradation of the polymer matrix phase as well as the loosening of the filler–matrix interface adhesion after aged …”

“…Some considerable effort has been devoted to understanding the thermal degradation of PBT and durability of its composites . Most of the previously completed durability works are focused on using GF as a PBT composite reinforcement and involve the incorporation of different heat stabilizers and oxidation inhibitors to retain its properties when subjected to thermo‐oxidative degradation . However, the current trend of focus has been shifted to the field of polymeric biocomposites with the use of natural constituents to replace synthetic fibers or fillers.…”

Mechanical, Heat-resistant, Crystallographic and Dynamical Mechanical Properties of Nylon 6/ P(N-phenylmaleimide-alt-styrene) Blends

“…DMA data for composites can provide the information about the storage modulus (G') and loss modulus (G'') of blends to give a better observation of the phase structure and interphase mixing of the blends [21,22]. Plots of the storage modulus (G') and loss modulus (G'') as a function of temperature for PA6/PNS blends with the frequency of 5 Hz are displayed in Figure 5 .…”

Study on the Synergetic Fire-Retardant Effect of Nano-Sb2O3 in PBT Matrix

“…However, neat PBT can easily burn if ignited, with a peak of heat release rate up to 1404 kw/m 2 . A large amount of heat would be released in the combustion process, which would cause increased fire accident fatalness [ 2 ]. Therefore, the development of PBT composite with comprehensive mechanical properties, flame retardancy, and cost-effectiveness has become a key to expand PBT application.…”