Abstract:Carbon fiber reinforced carbon (CFRC) composites, also called carbon/carbon (C/C) composites are materials with superior characteristics such as low density, good thermal shock resistance, high strength and low ablation under severe environments. Due to their properties, CFRC composites are ideal candidate in the high temperature fields. By pyrolysis process, carbon fiber phenolic resin composites are converted in C/C composites. The phenolic resin is a non-conductor (electrical resistivity of 1012 Ω.m) and du… Show more
“…The condensation of molecules from aromatic rings and the volatilization of these compounds lead to the weight loss and shrinkage of the phenolic resin. 36,37,39 At about 700 C, the phenolic resin is then converted slowly to amorphous carbon.…”
Section: Thermal Analysismentioning
confidence: 99%
“…From the DTG plots, there are two prominent peaks for both resins; the first peak lies in the temperature range of 100-130 C while the second lies in the range 460-550 C. The first peak is due to the curing reaction, while the second peak is due to the decomposition of the phenolic resin leaving behind a carbonaceous residue. [36][37][38] According to De Souza et al, 37 there are no significant molecular size changes up to 350 C; only small molecular bridge transformations occur because of the release of volatile free molecules, notably water and phenol. As the curing reaction started, the increase in these activated volatile free molecules gave rise to the monotonic increase in the DTG curve until it got to the maximum temperature of 100-130 C for both phenolic resoles.…”
The effects of microfiller addition on the flexural properties of carbon fiber reinforced phenolic (CFRP) matrix composites were investigated. The CFRP was produced using colloidal silica and silicon carbide (SiC) microfillers, 2 D woven carbon fibers, and two variants of phenolic resole (HRJ-15881 and SP-6877). The resins have the same phenol and solid content but differ in their viscosities and HCHO (formaldehyde) content. The weight fractions of microfillers incorporated into the phenolic matrix are 0.5 wt.%, 1 wt.%, 1.5 wt.%, and 2 wt.%. Flexural properties were determined using a three-point bending test and the damage evolution under flexural loading was investigated using optical and scanning electron microscopy. The results indicated that the reinforcement of phenolic resins with carbon fibers increased the flexural strength of the HRJ-15881 and SP-6877 by 508% and 909%, respectively. The flexural strength of the CFRP composites further increased with the addition of SiC particles up to 1 wt.% SiC but decreased with further increase in the amount of SiC particles. On the other hand, the flexural modulus of the CFRP composites generally decreased with the addition of SiC microfiller. Both the flexural strength and flexural modulus of the CFRP did not improve with the addition of colloidal silica particles. The decrease in flexural properties is caused by the agglomeration of the microfillers, with colloidal silica exhibiting more tendency for agglomeration than SiC. The fractured surfaces revealed fiber breakage, matrix cracking, and delamination under flexural loading. The tendency for failure worsened at microfiller addition of ≥1.5 wt.%.
“…The condensation of molecules from aromatic rings and the volatilization of these compounds lead to the weight loss and shrinkage of the phenolic resin. 36,37,39 At about 700 C, the phenolic resin is then converted slowly to amorphous carbon.…”
Section: Thermal Analysismentioning
confidence: 99%
“…From the DTG plots, there are two prominent peaks for both resins; the first peak lies in the temperature range of 100-130 C while the second lies in the range 460-550 C. The first peak is due to the curing reaction, while the second peak is due to the decomposition of the phenolic resin leaving behind a carbonaceous residue. [36][37][38] According to De Souza et al, 37 there are no significant molecular size changes up to 350 C; only small molecular bridge transformations occur because of the release of volatile free molecules, notably water and phenol. As the curing reaction started, the increase in these activated volatile free molecules gave rise to the monotonic increase in the DTG curve until it got to the maximum temperature of 100-130 C for both phenolic resoles.…”
The effects of microfiller addition on the flexural properties of carbon fiber reinforced phenolic (CFRP) matrix composites were investigated. The CFRP was produced using colloidal silica and silicon carbide (SiC) microfillers, 2 D woven carbon fibers, and two variants of phenolic resole (HRJ-15881 and SP-6877). The resins have the same phenol and solid content but differ in their viscosities and HCHO (formaldehyde) content. The weight fractions of microfillers incorporated into the phenolic matrix are 0.5 wt.%, 1 wt.%, 1.5 wt.%, and 2 wt.%. Flexural properties were determined using a three-point bending test and the damage evolution under flexural loading was investigated using optical and scanning electron microscopy. The results indicated that the reinforcement of phenolic resins with carbon fibers increased the flexural strength of the HRJ-15881 and SP-6877 by 508% and 909%, respectively. The flexural strength of the CFRP composites further increased with the addition of SiC particles up to 1 wt.% SiC but decreased with further increase in the amount of SiC particles. On the other hand, the flexural modulus of the CFRP composites generally decreased with the addition of SiC microfiller. Both the flexural strength and flexural modulus of the CFRP did not improve with the addition of colloidal silica particles. The decrease in flexural properties is caused by the agglomeration of the microfillers, with colloidal silica exhibiting more tendency for agglomeration than SiC. The fractured surfaces revealed fiber breakage, matrix cracking, and delamination under flexural loading. The tendency for failure worsened at microfiller addition of ≥1.5 wt.%.
“…The model assumed an initial electric conductivity until the onset of material decomposition, during decomposition the electrical conductivity was assumed to increase linearly, at 800 o C the epoxy was assumed to ablate and above this temperature a fully conductive value of electric conductivity was modelled (1x10 6 1/ Ω.mm). This relationship was based on TGA experiments within literature for epoxy [32]- [34]. In this case the energy released during resin decomposition was the same as that used for the unprotected laminate.…”
Preceding work has established that artificial test lightning plasma and composite test specimen damage can be modelled. However, no work has studied the impact of specimen representation in the modelling of the plasma and the resulting impact on specimen damage. Herein four distinct specimen designs have been modelled to understand the impact on plasma properties. The resulting specimen surface loads have then been passed to Finite Element (FE) damage models to predict thermal damage. A magnetohydrodynamic FE multiphysics model is employed to simulate the plasma and a FE thermalelectric modelling approach is used to predict the composite material damage. For the test arrangements modelled herein it has been found that specimen representation has limited impact on plasma global structure, even with significant change in specimen properties (e.g. from copper to epoxy). However, noteworthy variation in the local specimen surface loading is witnessed with specimen property change (e.g. epoxy to carbon reinforced epoxy), with peak magnitudes for surface pressure, velocity, current density and temperature changing by up to 88%. Such variation in local surface loading does significantly vary the prediction of thermal damage depth (up to 1200%) and surface damage area (up to 1314%). This work, for the first time, provides predictions for the thermal damage suffered by both protected and unprotected specimens exposed to test standard Waveform B.
“…Because of the presence of phenolic compounds such as phenol, 4-(1-methylethyl)-, phenol, p-tert-butyl-, p-isopropenylphenol, phenol, 4,4′-(1-methylethylidene)bis in the sC2 sample, the weight loss was estimated to be less in the TG–DTG curve measured from room temperature to 600 °C. Zhou et al and Souza et al reported the thermal decomposition of a phenolic resin converted to an amorphous carbon at 700 °C, and showed that the thermogravimetric loss rate of pure phenolic resin reached a maximum at 550 °C 27 , 28 . Figure 8 TG–DTG curves of Case III evidence.…”
Although there have been many instances of ship collision at sea in recent times, not much research has been conducted on the topic. In this study, paint from an actual site of ship collision was collected and analyzed as evidence. The amount of evidence collected from the ships involved in the collision is either small or has inconsistent morphology. In addition, the contaminants and samples are often mixed in this evidence, making its analysis difficult. Paint traces of the damaged ship and the ship suspected to be responsible for the collision were compared through scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDS), attenuated total reflection–Fourier transform infrared spectroscopy (ATR–FTIR), thermogravimetry (TG) and derivative thermogravimetry (DTG), and pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) analyses. The ship responsible for the collision could be identified by characterization and by performing a comparative analysis of the extracted paint. Among the methods used in this study, Py–GC/MS can sensitively analyze even similar paints, and identified styrene and phthalic anhydride as the most prominent components of the paint used as evidence. The results obtained can be used to investigate the evidence collected from collision sites and to determine the ship responsible for the collision.
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