Everson Kandare

The combined effect of epoxy nanocomposites and phosphorus flame retardant additives on thermal and fire reaction properties of fiber-reinforced composites

This study investigates the thermal stability of an aerospace grade epoxy resin containing a silicate-based nanoclay modified by an organophosphorus moiety (vinyl triphenyl phosphonium bromide; VTP), double-walled carbon nanotubes (DWCNTs) and/or conventional phosphorus containing flame retardants (FRs) at weight fractions up to 20% using thermogravimetric analysis (TGA). When FR additives (15 wt%) or VTP containing nanoclay (5 wt%) are used independently, the overall thermal stability enhancement of the epoxy resin follows the order; ammonium polyphosphate (APP) > nanoclay VTP > resorcinol bis-(diphenyl phosphate) (RDP) > tris-(tribromoneopentyl) phosphate (TBP). The addition of DWCNTs alone did not significantly alter the thermal stability of the epoxy resin matrix. The concomitant addition of VTP together with RDP, APP, and TBP at a cumulative weight fraction of 20% led to synergistic improvements in the thermal stability of the resin. The fire reaction properties of the glass fiber-reinforced laminates prepared from modified resin formulations were measured under cone calorimetry conditions at an incident heat flux of 50 kW/m2. The addition of conventional FRs with or without the nanoclay significantly reduced the peak value heat release rate and total heat release relative to the control sample. DWCNTs alone did not show a significant effect on the fire reaction properties of the epoxy resin composites. The burning behavior of the flame-retarded samples as evaluated by cone calorimetry correlated very well with TGA and differential thermal analysis (DTA) data. The depolymerization intensity as measured from DTA data agreed with PHRR from cone calorimetry while the TTI showed a direct correlation to the onset of thermal degradation as determined from TGA data. According to a fire risk assessment based on cone calorimetry data, nanocomposites containing APP achieved the highest fire safety rating.

Preparation and Characterization of Core/Shell-like Intumescent Flame Retardant and its Application in Polypropylene

With a shell of starch-melamine-formaldehyde (SMF) resin, core/shell-like ammonium polyphosphate (SMFAPP) is prepared by in situ polymerization, and is characterized by SEM, FTIR and XPS. The shell leads SMFAPP a high water resistance and flame retardance compared with APP in polypropylene (PP). The flame retardant action of SMFAPP and APP in PP are studied using LOI, UL 94 test and cone calorimeter, and their thermal stability is evaluated by TG. The flame retardancy and water resistance of the PP/SMFAPP composite at the same loading is better than that of the PP/APP composite. UL 94 ratings of PP/SMFAPP can reach V-0 at 30 wt% loading. The flame retardant mechanism of SMFAPP was studied by dynamic FTIR, TG and cone calorimeter, etc.

Thermal stability and degradation kinetics of polystyrene/organically- modified montmorillonite nanocomposites

Organically-modified montmorillonite (MMT) clays have been prepared using ammonium salts containing quinoline, pyridine, benzene, and styrenic groups. The nanocomposites were prepared by melt blending and the formation of nanocomposites was characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal stability and flammability were evaluated by thermogravimetric analysis (TGA) and cone calorimetry measurements, respectively. The presence of modified MMT at 5% loading resulted in significant improvement in thermal stability compared to the virgin polymer. Effective activation energies for mass loss were determined via a model-free isoconversional approach from TGA data obtained under N2 and under air. The additives served to raise the activation energy, with a more significant impact observed under pyrolysis conditions. The onset temperature of degradation and temperature of maximum decomposition rate are increased, while the peak heat release rate and mass loss rates are significantly reduced in the presence of three of the modified clays. No reduction in the total heat released is observed.

Chapter 13:Thermal and Fire Performance of Flame-Retarded Epoxy Resin: Investigating Interaction Between Resorcinol Bis(Diphenyl Phosphate) and Epoxy Nanocomposites

The flammability of polymeric materials has always been a great concern, because it limits their use in applications where fire safety is a key criterion. The use of both halogenated and non-halogenated conventional flame retardants has proved to be an effective solution to the problem, and resulted...