Abstract
Carbon fibre reinforced flame-retarded bioepoxy composites were prepared from commercially available sorbitol polyglycidyl ether (SPE) cured with cycloaliphatic amine hardener. Samples containing 1, 2, and 3% phosphorus (P) were prepared using additive type flame retardants (FRs) resorcinol bis(diphenyl phosphate) (RDP), ammonium polyphosphate (APP), and their combinations. The fire performance of the composites was investigated by limiting oxygen index (LOI), UL-94 tests, and mass loss calorimetry. The effect of FRs on the glass transition temperature, and storage modulus was evaluated by dynamic mechanical analysis (DMA), while the mechanical performance was investigated by tensile, bending, and interlaminar shear measurements, as well as by Charpy impact test. In formulations containing both FRs, the presence of RDP, acting mainly in gas phase, ensured balanced gas and solid-phase mechanism leading to best overall fire performance. APP advantageously compensated the plasticizing (storage modulus and glass transition temperature decreasing) effect of RDP in combined formulations; furthermore, it led to increased tensile strength and Charpy impact energy.
Highlights
The need for the development of polymers originating from renewable resources is increasing with the decreasing amount of the mineral oil stock and with the spreading of environmental awareness.This tendency has emerged in the polymer composite industry, including such demanding sectors as automotive and aircraft applications [1], where high performance thermosetting materials are applied
From the results glass transition temperature based on the tan delta peaks (Tg ) and storage modulus (E’) values at 25 ◦ C and 75 ◦ C were determined by the software of the device (TA Instruments Universal Analysis 2000 4.7A version)
From the two flame retardants, the ammonium polyphosphate (APP) seemed to be more advantageous in terms of limiting oxygen index (LOI): by adding 3% P through APP, LOI of 31 V/V% was reached, while with the same P-content the resorcinol bis(diphenyl phosphate) (RDP)
Summary
The need for the development of polymers originating from renewable resources is increasing with the decreasing amount of the mineral oil stock and with the spreading of environmental awareness. This tendency has emerged in the polymer composite industry, including such demanding sectors as automotive and aircraft applications [1], where high performance thermosetting materials (such as epoxy resins) are applied. In order to fulfil the strict safety requirements of high-tech applications, effective flame retardation of the composites has to be elaborated while maintaining mechanical properties at an appropriate level [12,13]. Interlaminar shear strength (ILSS) of the composites was determined in order to get insight into the quality of the fibre-matrix adhesion
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