A Promising Thermodynamic Study of Hole Transport Materials to Develop Solar Cells: 1,3-Bis(N-carbazolyl)benzene and 1,4-Bis(diphenylamino)benzene

The thermochemical study of the 1,3-bis(N-carbazolyl)benzene (NCB) and 1,4-bis(diphenylamino)benzene (DAB) involved the combination of combustion calorimetric (CC) and thermogravimetric techniques. The molar heat capacities over the temperature range of (274.15 to 332.15) K, as well as the melting temperatures and enthalpies of fusion were measured for both compounds by differential scanning calorimetry (DSC). The standard molar enthalpies of formation in the crystalline phase were calculated from the values of combustion energy, which in turn were measured using a semi-micro combustion calorimeter. From the thermogravimetric analysis (TGA), the rate of mass loss as a function of the temperature was measured, which was then correlated with Langmuir’s equation to derive the vaporization enthalpies for both compounds. From the combination of experimental thermodynamic parameters, it was possible to derive the enthalpy of formation in the gaseous state of each of the title compounds. This parameter was also estimated from computational studies using the G3MP2B3 composite method. To prove the identity of the compounds, the 1H and 13C spectra were determined by nuclear magnetic resonance (NMR), and the Raman spectra of the study compounds of this work were obtained.

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.

Synthesis of a novel aluminium salt of nitrogen-containing alkylphosphinate with high char formation to flame retard acrylonitrile–butadiene–styrene

A novel nitrogen-containing alkylphosphinate salt—aluminium β-(p-nitrobenzamide) ethyl methyl phosphinate (AlNP) was synthesized and used to flame retard acrylonitrile–butadiene–styrene copolymer (ABS). The Fourier transform infrared spectrometry, 1 H, 13 C and 31 P nuclear magnetic resonance and X-ray fluorescent spectroscopy (XRF) were applied to characterize the structure and composition of products. The flame retardancy performance, thermal properties and mechanical strength of the ABS/AlNP with respect to AlNP loading were investigated. AlNP was stable before 330°C and decomposed very slowly with residues high up to 56.1% at 700°C. Adding 25–30 wt% of AlNP alone can make ABS to pass V0 rating in the vertical burning tests (UL 94). The results according to the micro combustion calorimeter, thermogravimetric analysis showed that AlNP can depress the heating release and retard the thermal degradation of the ABS. Scanning electron microscopy observation of the residues from LOI test indicated that AlNP formed the condensed and tough residues layer during combustion; XRF analysis showed that the residues contained phosphorus and aluminium element and nitrogen element was not detected. The compact phosphorus/aluminium-rich substance acted as a barrier to enhance flame-retardant properties of the ABS.

Thermal properties of wool fabric treated by phosphorus-doped silica sols through sol-gel method

Wool fabric was treated with silica sol and phosphorus doped silica sol by sol-gel method in order to improve its thermal properties and flame retardance. The thermal stability, combustion behavior, and smoke suppression of the control and finished wool fabric were analyzed using thermogravimetric analysis, limited oxygen index, micro combustion calorimeter, and smoke chamber. The results showed that wool fabric treated by phosphorus doped silica sol had excellent thermal properties and flame retardance with higher final char residue and LOI value. Furthermore, heat release rate and smoke density results indicated the safety performance of the treated wool fabric on fire.

Temperature Dependent Solid Fuel Combustion Characterization and Fuel Ranking

Fuel combustion performance was quantified through measurement of the gravimetric response of the fuel as well as the energetic behavior. A Simultaneous Thermogravimetric Analyzer (STA) was used to measure the gravimetric, sensible energy, and latent heat energy (including heat of pyrolysis) for fuels. The heat release rate and heat of combustion of the fuels as a function of temperature released due to the combustion of the pyrolysis gases was measured using a Micro-Combustion Calorimeter (MCC). Fuels were tested at a heating rate of 20°C/min from room temperature to 800°C in inert (nitrogen) environment. Fuels considered in this study included US eastern coal, biomass (cornstover and switchgrass), polystyrene, glycerol and mixtures of some of these fuels. Biomass feedstocks were also evaluated for the effect of water leaching on fuel performance. A lumped model energy balance on a fuel particle revealed that fuel volatility can be ranked based on the net energy required to produce the volatile gas times the ratio of the heat of combustion to the heat of decomposition. This is different compared with previous research results in that it includes the temperature dependence of the fuel production in the volatility.