Authors:M. Ginic-Markovic, N. Roy Choudhury, J. Matisons, and N. Dutta
The present investigation focuses on matching cure characteristics of EPDM rubber compound and polyurethane (PU) coating using
temperature modulated and pressure differential scanning calorimetry (TMDSC, PDSC).
TMDSC provides a detailed and better understanding of the curing process of model rubber system as well as complex automotive
rubber compounds. The low level of unsaturation present in EPDM, results in the small heat of vulcanization (2–5 J g–1), which is difficult to accurately measure using conventional differential scanning calorimetry (DSC). Thus, curing of highly
filled EPDM compound was investigated using TMDSC.
The kinetics of PU curing was monitored using pressure DSC (PDSC), and heat of curing was determined as 4.2 J g–1 at 10C min–1 heating rate. It is found that complex automotive compounds and the PU coating are curing simultaneously.
The design and operation of a bench-top high-pressure thermogravimetric analyser is described and illustrated. It has the following specifications: sample mass 1–100 mg; temperature range 25–700°; heating rate 0.1–10 deg/min; pressure range 0–50 bar of air, O2, N2, CO2, CO or H2. Mass and temperature are measured with a maximum error of 0.1 mg and 5 K for any conditions of pressure, temperature and heating rate. The instrument can be used to study substances under industrially realistic conditions of pressure and temperature and to perform high-pressure accelerated oxidation tests on lubricants and polymers. In these areas of application, the instrument offers a new standard of accuracy and ease of use which make it comparable to commercially available high-pressure DSC systems.
Authors:L. Ji-zhen, F. Xue-zhong, H. Rong-zu, Z. Xiao-dong, Z. Feng-qi, and G. Hong-Xu
The thermal behavior of copper(II) 4-nitroimidazolate (CuNI) under static and dynamic states are studied by means of high-pressure
DSC (PDSC) and TG with the different heating rates and the combination technique of in situ thermolysis cell with rapid-scan
Fourier transform infrared spectroscopy (thermolysis/RSFTIR).
The results show that the apparent activation energy and pre-exponential factor of the major exothermic decomposition reaction
of CuNI obtained by Kissinger’s method are 233.2 kJ mol−1 and 1017.95 s−1, respectively. The critical temperature of the thermal explosion and the adiabatic time-to-explosion of CuNI are 601.97 K
and 4.4∼4.6 s, respectively. The decomposition of CuNI begins with the split of the C-NO2 and C-H bonds, and the decomposition process of CuNI under dynamic states occurs less readily than those under static states
because the dynamic nitrogen removes the strong oxidative decomposition product (NO2). The above-mentioned information on thermal behavior is quite useful for analyzing and evaluating the stability and thermal
charge rule of CuNI.
A characteristic index
for the oxidation stability this is the oxidation induction time (OIT) which
is defined by the time between the start of oxygen exposure and the onset
of oxidation. Pressure DSC is required to increase oxygen concentration in
order to achieve faster reactions at lower temperatures. OIT measurements
of reference engine oils have been used to study the influence of oxygen pressure
in the range from 0.1 to 10 MPa. A power law relationship was derived to describe
this correlation between OIT and oxygen pressure. From this a quantitation
factor is proposed to represent the influence of stabilizer. The exponent
describes the sensitivity of the oxidation reaction of the oil towards the
oxygen pressure and the term 'inherent stability' is proposed
for that.. This relationship characterizes in more details the oxidation behavior.
Extrapolation to higher pressures indicates, that the stabilization effects
of additives can be overcome by the inherent stability. This signifies, that
the ranking of the oils can be affected by the oxygen pressure.
Authors:L. Jizhen, F. Xuezhong, F. Xiping, Z. Fengqi, and H. Rongzu
of 1,3,3-trinitroazetidine (TNAZ) with some energetic components and inert
materials of solid propellants was studied by using the pressure DSC method.
Where, cyclotetramethylenetetranitroamine (HMX), cyclotrimethylenetrinitramine
(RDX), nitrocellulose (NC), nitroglycerine (NG), 1.25/1-NC/NG mixture, lead
3-nitro-1,2,4-triazol-5-onate (NTO-Pb), aluminum powder (Al powder) and N-nitrodihydroxyethylaminedinitrate
(DINA) were used as energetic components and hydroxyl terminated polybutadiene
(HTPB), carboxyl terminated polybutadiene (CTPB), polyethylene glycol (PEG),
polyoxytetramethylene- co-oxyethylene (PET), addition product of hexamethylene
diisocyanate and water (N-100), 2-nitrodianiline (2-NDPA), 1,3-dimethyl-1,3-diphenyl
urea (C2), carbon black (C.B.), aluminum oxide (Al2O3),
cupric 2,4-dihydroxybenzoate (β-Cu), cupric adipate (AD-Cu) and lead
phthalate (ϕ-Pb) were used as inert materials. The results showed that
the binary systems of TNAZ with HMX, NC, NG, NC+NG and DINA are compatible,
with RDX and Al powder are slightly sensitive, with NTO-Pb, β-Cu, AD-Cu,
C.B. and Al2O3 are sensitive, and with HTPB, CTPB, PEG, PET, N-100, 2-NDPA,
C2 and ϕ-Pb are incompatible.
Authors:Magdalena Wirkowska, Ewa Ostrowska-Ligęza, Agata Górska, and Piotr Koczoń
for standard DSC. A normal-pressureDSC cell was used. Fat samples of 3–4 mg were placed in aluminium sample pans and inserted into the heating chamber of the DSC cell. The aluminium reference pan was left empty. Samples of compounds were heated in an