Search Results

You are looking at 1 - 10 of 41 items for

  • Author or Editor: C. Shu x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

Investigations of nitrogen content and thermal decomposition activation energy (E a) of two different kinds of nitrocellulose (NC) products, NMNC and MNC from the non-fat and original processes of linters, respectively, were discussed. In this study, differential scanning calorimetry (DSC) and element analyzer (EA) are used, for the above two chemicals, along with the same nitration condition in use of sulfuric acid (H2SO4) and nitric acid (HNO3) mixing acid. E a was calculated by our induced model. According to our experimental results, the nitrogen content of NMNC/MNC was 11.71 and 11.55 mass%, in a low nitrogen content condition of mixing acid. The E a parameters were 319.91 (NMNC) and 347.27 (MNC) kJ mol−1, individually. They indicated that the non-fat process of a linter made a higher degree of stability than the others. This research also presents an efficient and accurate model of the thermal decomposition property evaluation for non-fat process of linters. The outcome is believed to be very useful for helping to understand, and be applied as, an inherently safer design during relevant NC manufacturing processes.

Restricted access

Abstract  

Diphenylcarbonate (DPC) has been regarded as a potential substitute material for highly toxic phosgene, reacting with bisphenol A (BPA) in a phosgene-free process to produce polycarbonate (PC). For synthesizing DPC, methylphenylcarbonate (MPC) was the critical intermediate with potential flammability in a transesterification reaction from dimethylcarbonate (DMC) and phenol. Under the National Fire Protection Association (NFPA) criterion, MPC is viewed as one sort of combustible liquid (Class IIIB). Once it fires or burns during storage, operation or transportation, it can cause a serious fire and explosion. However, researches are still scanty in mentioning the basic but crucial fire and explosion features of MPC to date. A sound background of material safety properties is essential for safe handling; in particular, flammability information is extremely crucial for a specific chemical during a unit operation to prevent any fire and explosion hazards. In this study, we investigated the explosion limits (LEL, UEL), maximum explosion pressure (P max), maximum rate of explosion pressure rise ((dP/dt)max), and gas or vapor explosion constant (K g) of MPC, according to its practical operating conditions (1 atm, 250°C, 21 vol.% O2) and by means of a 20 L vessel (20-L-Apparatus). By surveying and defining the experimental data through flammability tests, these basic but crucial safety-related parameters on flammability characteristics of MPC were proposed, so as to advance understanding and to avoid fire and explosion accidents for such relevant processes.

Restricted access

Abstract  

Information about the kinetics and thermal decomposition of hydrogen peroxide (H2O2) has been required for safety reasons, due to its broad applications in many chemical industries. To determine the inherent hazards during H2O2 manufacturing, transportation, disposal, usage, and so on, this study deliberately selected various H2O2 concentrations and analyzed them by differential scanning calorimetry (DSC). In addition, thermokinetic parameters were not only established for each of these reactions, but also aimed at comprehensive, kinetic models with various tests conducted at different heating rates. To build up a comprehensive kinetic model, various tests were conducted by heating rates of 1, 2, 4, 10C min–1, respectively. According to dynamic DSC tests, the experimental curves show that H2O2 decomposition has one exothermic peak and may start to decompose under 47–81C. The total heat of decomposition is about 192–1079 J g–1. Not only can these results prevent accidents caused by H2O2 during storage and transportation, but also assess its inherent hazards and thereby design procedures for emergency response while runaway reactions occurring.

Restricted access

Abstract  

Thermal runaway reactions associated with exothermic behaviors of tert-butyl hydroperoxide (TBHP) solutions and TBHP reacting with alkaline contaminants were studied. A differential scanning calorimetry (DSC) was used to characterize these inherent behaviors of TBHP solutions with KOH, NaOH, LiOH and NH4OH. The exothermic peak in thermal curves of TBHP solutions with different alkali were detected by DSC thermal analysis. By thermal analysis, we compared various heats of decomposition of TBHP solutions with alkaline impurities, and determined the incompatible hazards of various TBHP solutions with alkaline contaminants. Comparing with TBHP in various diluents, the adiabatic runaway reaction via vent sizing package 2 (VSP2) indicated that aqueous TBHP intrinsically possesses the phenomena of thermal explosion with dramatic self-reactive rate and pressure rise under adiabatic conditions. Many commercial organic peroxides may have different hazard behaviors. Therefore, using thermal method to classify the hazards is an important subject.

Restricted access

Abstract  

Analytical equations related adiabatic runaway reactions to programmed scanning thermal curves from differential scanning calorimetry (DSC) were proposed. Thermal or pressure hazards can be assessed from the adiabatic trajectories expressed in the analytical equations. These industrially energetic materials include polymerizable monomers, unstable organic peroxides and nitro-compounds. Various emergency relief behaviors, such as tempered vapor, gassy, and hybrid were re-evaluated for calculating vent sizing or mass flow rates from DSC thermal curves and the related physical properties.

Restricted access

Abstract  

Information about the kinetics and thermal decomposition of dicumyl peroxide (DCPO) is required for safety concerns, due to its wide applications and accident cases. To understand the inherent hazards during DCPO manufacturing, we selected various concentrations in different stages and analyzed them by differential scanning calorimetry (DSC). We evaluated thermokinetic parameters to set up a simple, but comprehensive kinetic model, with various tests conducted at heating rates of 2, 4, 6 and 10C min-1 . Subsequently, we established a more efficient, resource-effective, and cost-effective model of safety evaluation for DCPO with different concentrations, according to thermokinetic parameters, such as activation energy E a is 125.35 kJ mol-1 , frequency factor k 0 is 3.12410 12 s-1 , reaction order n is 0.9 and heat of decomposition ΔH is 750.52 J g-1 for DCPO 99 mass%.

Restricted access
Restricted access

Letter to the Editor

Response to comments for thermal explosion and runaway reaction simulation of lauroyl peroxide by DSC tests

Journal of Thermal Analysis and Calorimetry
Authors:
M.-L. You
and
C.-M. Shu
Restricted access

Abstract  

This study discussed the phenomena on thermal polymerization of α-methylstyrene (AMS). A curve scanned by temperature-programmed technique was performed by differential scanning calorimetry (DSC). Heat of polymerization (ΔH) and onset temperature of exothermic (T 0) behavior were determined to be 28010 J g-1 and about 1381C, respectively. A dimer formation mechanism was proposed for initiation of the propagating chain. Spectroscopic identification of dimer structure was conducted by infrared (IR) spectroscopy in the wavenumber from 650 to 1100 cm-1associated with molecular fingerprint characteristics. The mechanism of thermal polymerization on α-methylstyrene proposed in this study was similar to that of styrene suggested by Mayo.

Restricted access

Abstract  

Knowledge of material safety properties is critical for safe handing in the chemical process industries, especially for flammable chemicals that might result in serious fires and explosions. This study investigated the flammability characteristics of methanol under working conditions during the process. The targeted fire and explosion properties, like explosion limits (UEL and LEL), vapor deflagration index (K g), maximum explosion pressure (P max), and maximum explosion pressure rise [(dP dt −1)max], were deliberately obtained via a 20-L-Apparatus in 101 kPa (i.e., 760 mmHg/1 atm), 150 and 200 °C, along with various experimental arrangements containing nitrogen (N2) or carbon dioxide (CO2) as inert component. Particularly, this study discussed and elucidated the inert influence on the above safety-related parameters by two different inerting gases of N2 and CO2. The results indicated that adding an inert component to fuel–inert gas mixtures determined the decrease of explosion range and flammability hazard degree. The results also demonstrated that CO2 possessed higher inerting capability than N2 in this study.

Restricted access