Wood Dust Flammability Analysis by Microscale Combustion Calorimetry

To study the practicability of a micro combustion calorimeter to analyze the calorimetry kinetics of wood, a micro combustion calorimeter with 13 heating rates from 0.1 to 5.5 K/s was used to perform the analysis of 10 kinds of common hardwood and softwood samples. As a microscale combustion measurement method, MCC (microscale combustion calorimetry) can be used to judge the flammability of materials. However, there are two methods for measuring MCC: Method A and Method B. However, there is no uniform standard for the application of combustible MCC methods. In this study, the two MCC standard measurement Methods A and B were employed to check their practicability. With Method A, the maximum specific heat release rate, heat release temperature, and specific heat release of the samples were obtained at different heating rates, while for Method B, the maximum specific combustion rate, combustion temperature and net calorific values of the samples were obtained at different heating rates. The ignition capacity and heat release capacity were then derived and evaluated for all the common hardwood and softwood samples. The results obtained by the two methods have significant differences in the shape of the specific heat release rate curves and the amplitude of the characteristic parameters, which lead to the differences of the derived parameters. A comparison of the specific heat release and the net calorific heat of combustion with the gross caloric values and heating values obtained by bomb calorimetry was also made. The results show that Method B has the potentiality to evaluate the amount of combustion heat release of materials.

Pyrolysis and combustion of polystyrene composites based on graphene oxide functionalized with 3-(methacryloyloxy)-propyltrimethoxysilane

In this study, polystyrene composites (PS–GOf) with variable concentration (0.5; 1; 2; 3; 4; and 5 wt%) of GOf were obtained through the in-situ polymerisation of the styrene in the presence of benzoyl peroxide and graphene oxide(GO) functionalized with 3-(methacryloyloxy)-propyltrimethoxysilane(γ-MPTS). For determining the morphological and structural particularities of polymeric composites transmission electron microscopy (TEM) measurements were performed. The influence of functionalized GO on thermal and combustion properties of polystyrene (PS)-based composite materials was determined through several methods: Thermogravimetry (TGA); derived thermogravimetry (DTG); microscale combustion calorimetry analysis (MCC); and chemical kinetic studies through TGA and MCC determinations at similar heating rates.

Polyisocyanurate Foam Pyrolysis and Flame Spread Modeling

Polyisocyanurate (PIR) foam is a robust thermal insulation material utilized widely in the modern construction. In this work, the flammability of one representative example of this material was studied systematically using experiments and modeling. The thermal decomposition of this material was analyzed through thermogravimetric analysis, differential scanning calorimetry, and microscale combustion calorimetry. The thermal transport properties of the pyrolyzing foam were evaluated using Controlled Atmosphere Pyrolysis Apparatus II experiments. Cone calorimetry tests were also carried out on the foam samples to quantify the contribution of the blowing agent (contained within the foam) to its flammability, which was found to be significant. A complete pyrolysis property set was developed and was shown to accurately predict the results of all aforementioned measurements. The foam was also subjected to full-scale flame spread tests, similar to the Single Burning Item test. A previously developed modeling approach based on a coupling between detailed pyrolysis simulations and a spatially-resolved relationship between the total heat release rate and heat feedback from the flame, derived from the experiments on a different material in the same experimental setup, was found to successfully predict the evolution of the heat release rate measured in the full-scale tests on the PIR foam.

Development of a pyrolysis model for oriented strand board. Part I: Kinetics and thermodynamics of the thermal decomposition

Oriented strand board is a widely used construction material responsible for a substantial portion of the fire load of many buildings. To accurately model the response of oriented strand board to fire, thermogravimetric analysis, differential scanning calorimetry, and microscale combustion calorimetry tests were carried out to construct a thermal decomposition model using a numerical solver, ThermaKin, and a hill climbing optimization algorithm. The model included a single-step water vaporization reaction and four consecutive reactions representing thermal decomposition of organic constituents of oriented strand board. The experiments and modeling revealed that the first two of the four reactions are endothermic, while the last two are exothermic. The net heat of decomposition was found to be near zero. The heat capacities of condensed-phase species and heats of combustion of evolved gases were also determined. The heats of combustion were found to vary over the course of decomposition—the trend captured by the model. Development of a complete pyrolysis model for this material will be a subject of Part II of this work.

Investigation on the effect of supported synergistic catalyst with intumescent flame retardant in polypropylene

In this paper, cerium nitrate supported silica was prepared as a new type of catalytic synergist to improve the flame retardancy in polypropylene. When 1% of Ce(NO3)2 supported SiO2 was added, the vertical combustion performance of UL-94 of polypropylene composites was improved to V-0, the limiting oxygen index (LOI) was increased to 33.5. From the thermogravimetric analysis (TGA), the residual carbon of C and D was increased by about 6% at high temperature compared with B. When adding supported catalyst, the heat release rate (HRR) and total heat release (THR) were significantly reduced according to the microscale combustion calorimetry (MCC), the HRR of sample E with 2% synergist was the lowest. The combustion behaviors of intumescent flame retardant sample B and sample D were analyzed by cone calorimeter test (CCT), the HRR of sample D with supported synergist was significantly reduced, and the PHRR decreased from 323 kW/m2 to 264 kW/m2. The morphologies of the residue chars after vertical combustion of polypropylene composites observed by scanning electron microscopy (SEM) gave positive evidence that the supported synergist could catalyze the decomposition of intumescent flame retardants into carbon, which was the main reason for improving the flame retardancy of materials.