Study On Aging Properties Of Glass/Carbon Hybrid Fibers Reinforced Composite Cable Core Via Pultrusion Technology

Aging behaviors of glass/carbon hybrid fibers reinforced epoxy resin composite cable core were studied in various simulated environments respectively. Absorption characteristics of the composites in distilled water, 10wt% NaCl aqueous solution, 10wt% H2SO4 aqueous solution and 5wt% NaOH aqueous solution were investigated. Moreover, effects of the environments on static and dynamic mechanical properties and aging mechanisms were analyzed. The service life of the cable core was also predicted on the basis of experimental hygrothermal aging data.The experimental results of moisture absorption ratio show that the absorption characteristics of the hybrid composite cable core obey the Fick's law in the early period, however, large deviations arise for the cable core in distilled water and 10wt% NaCl aqueous solution in the following time of the experiment. In 10wt% H2SO4 aqueous solution, the absorption behavior agrees with the Fick's law at the early stage, while the nominal moisture content decreases a little at the later stage. The moisture content of the cable core in 5wt% NaOH aqueous solution increases linearly at first and thereafter decreases, and then increases with the prolongation of immersion time. Moreover, the increase of environmental temperature leads to a faster diffusion of water in the composites and a higher equilibrium moisture content.Effects of the hygrothermal aging on the dynamic mechanical properties of the hybrid composite cable core were studied by dynamic mechanical analysis (DMA). The results show that the storage modulus ( ) of the composites decreases with increasing immersion time, while the loss factor (tanE'δ) increases simultaneously. Furthermore, the higher the temperature the more remarkable the effects. The glass transition temperature (Tg) of the composite is relative to the moisture content.The flexural and shear properties of the hybrid composite cable core were measured on an universal testing instrument to study effects of the environments on the static mechanical properties of the composites. Results indicate that environmental aging results in the decrease in the flexural and shear properties of the hybrid composite cable core. The decrease amplitude minishs gradually. Under different temperatures, the decrease of mechanical properties of the composites was uniform, and higher temperature accelerates the composites aging.Results of infrared spectrometer (IR) and scanning electron microscope (SEM) show that the composites in distilled water and 10wt% NaCl aqueous solution have the same aging mechanisms, which consists of the swelling and plasticization of matrix, interfacial debonding and resultant microstructure changes of matrix and interface. No chemical reactions can be observed. While in 10wt% H2SO4 aqueous solution and 5wt% NaOH aqueous solution, chemical aging is found.Based on accelerated hygrothermal aging test of the hybrid composite cable core, a service-life prediction equation for the composite cable core with high confidence and reliability was developed in the paper. Furthermore, the service life of the cable core was estimated according to the environment equivalence.