Comparison of Pentaerythrotol and Its Derivatives as Intumescent Flame Retardants for Polypropylene

Hydroquinol bis[di(2,6,7-trioxa-phosphabicyclo[2.2.2]-octane-1-oxo-4-hydroxylmethyl)]phosphate (PBPP), which contains caged phosphates and benzene groups, was synthesized. The caged phosphate structure of PBPP was characterized by Fourier transform infrared spectroscopy (FT-IR), hydrogen nuclear magnetic resonance (1H-NMR), and phosphorus nuclear magnetic resonance (31P-NMR). The experimental results showed that PBPP had better performance than 1-oxo-4-hydroxymethy1-2,6,7-trioxa-1-phosphabicyclo[2.2.2]-octane (PEPA) and pentaerythritol (PER) in water resistance, compatibility with polypropylene (PP), thermal stability, and flame retardancy of intumescent flame retardant PP (IFR-PP) systems. It was attributed to the symmetrical structure and stereohindrance effect of PBPP. The IFR-PP systems reached UL94 V-0 flammability rating when the minimal addition of IFR with PBPP, PEPA, or PER was 25%, 23%, and 28%, respectively. The flame retardant mechanisms of IFR containing PBPP, PEPA, and PER were investigated by FT-IR and scanning electron microscopy (SEM). PBPP formed a perfect charring layer, with the high carbon content of PBPP helping it form the charring layer more quickly.

Reaction kinetics and a physical model of the charring layer by depositing Al2O3 at ultra-high temperatures

The thermochemical ablation of insulation material caused by slag deposition in solid rocket motors has increasingly attracted researchers’ attention.

Thermal Degradation of Hemp Treated with Guanidine Dihydrogen Phosphate

Hemp was treated with guanidine dihydrogen phosphate [GDP] to impart flame retardance. The thermal degradation of the samples were studied by thermogravimetry (TG) and differential thermal analysis (DTA). The flame retardance was determined by LOI. Morphology of the char structure was studied by SEM to obtain information concerning the thermal degradation mechanism. For hemp treated with GDP, which has higher LOI and char yield values, the oxidative decomposition stages include a decomposition stage at lower temperatures (165-240°C) , leading to more carbonaceous residue and small amount of flammable products to get the good flame retardance. The SEM of the chars of hemp treated with GDP also indicate the structure of the charring layer may increase heat insulation, and protect inner matrix materials.

Thermal Degradation of Hemp Treated with Guanidine Nitrate

Hemp was treated with guanidine nitrate to impart flame retardance. The thermal degradation of the samples were studied by thermogravimetry (TG) and differential thermal analysis (DTA). The flame retardance was determined by LOI. Morphology of the char structure was studied by SEM to obtain information concerning the thermal degradation mechanism. For hemp treated with guanidine nitrate, which has higher LOI and char yield values, the oxidative decomposition stages include a decomposition stage at lower temperatures (203-240°C) , leading to more carbonaceous residue and small amount of flammable products to get the good flame retardance. The SEM of the chars of hemp treated with guanidine nitrate also indicate the structure of the charring layer may increase heat insulation, and protect inner matrix materials.

Thermal Degradation of Hemp Treated with Guanidine Carbonate

Hemp was treated with guanidine carbonate to impart flame retardance. The thermal degradation of the samples were studied by thermogravimetry (TG) and differential thermal analysis (DTA). The flame retardance was determined by LOI. Morphology of the char structure was studied by SEM to obtain information concerning the thermal degradation mechanism. For hemp treated with guanidine carbonate, which has higher LOI and char yield values, the oxidative decomposition stages include a decomposition stage at lower temperatures (172-210°C) , leading to more carbonaceous residue and small amount of flammable products to get the good flame retardance. The SEM of the chars of hemp treated with guanidine carbonate also indicate the structure of the charring layer may increase heat insulation, and protect inner matrix materials.

Research on Mechanical Model of EPDM Insulation Charring Layer

The coupling effect of physics, chemistry and mechanics is through charring layer in the process of ablation of the insulation material. Description of the structure and mechanical properties of charring layer is the critical factor to numerical computation for foretelling the ablation of insulation material. The characteristic of charring layer structure of EPDM insulation at sorts of ablating condition were analyzed, and based on characteristic of porous medium of charring layer, the mechanical model with porosity as parameter was modeled by using theory of solid porous medium. According to the intensity determination of charring layer, the coefficient of intensity model was determined, then, the failure criterion of charring layer was set up, which can provide the mechanical parameters of charring layer for numerical computation to foretell the ablation of insulation material.