Authors:B. Lin, L. Yang, H. Dai, Q. Hou, and L. Zhang
Soybean oil based polyols (5-OH polyol, 10-OH polyol and 15-OH polyol) were synthetised from epoxidized soybean oil. The melting
peak of polyols and the relationship between melting peak and the number-average functionality of hydroxyl in polyols were
investigated by differential scanning calorimetry (DSC). The thermal decomposition of polyols and some of their thermal properties
by thermogravimetry (TG) and derivative thermogravimetry (DTG) were also studied. The thermal stability of polyols in a nitrogen
atmosphere was very close hence they had a same baseplate of triglyceride for polyols. The extrapolated onset temperature
of polyols in their thermal mass loss, first step had a decreasing order: 5-OH polyol>10-OH polyol>15-OH polyol due to the
difficulty in forming multiple elements ring of them had the same order.
The thermal behavior of polyols under non-isothermal conditions using Friedman’s differential isoconversional method with
different heating rates indicated that the 5-OH polyol had the lowest activation energy in thermal decomposition amongst these
polyols according to the same fractional mass loss because of the weakest intramolecular oligomerization. The 15-OH polyol
was prior to reach the mass loss region because the six-member ring is more stable than the three-member ring from 10-OH polyol
and more easily formed.
Authors:M. Ştefănescu, M. Stoia, O. Ştefănescu, A. Popa, M. Simon, and C. Ionescu
Hybrid organic-inorganic materials,
silica – polyols (ethylene-glycol – EG; 1,2 propane diol –
1,2PG; 1,3 propane diol – 1,3PG and glycerol – GL), were prepared
by a sol-gel process starting from tetraethylorthosilicate (TEOS) and polyols,
in acid catalysis. The resulting materials were studied by thermal analysis
(in air and nitrogen), FTIR and solid state 29Si-NMR
spectroscopy. These techniques evidenced the presence of polyols in the silica
matrix both hydrogen bounded and chemically bounded in the silica network.
The thermal analysis proves to be the most appropriate technique to evidence
the organic chains linked in the matrix network and to follow the thermal
evolution of the gels to the SiO2 matrix.
Authors:Alberto Albis, José Manuel Lozano, Javier Sancho, and Carmen M. Romero
that the presence of other substances can affect the LA stability positively, increasing stability, or negatively, decreasing protein stability [ 10 – 15 ].
Polyols have been used extensively to improve stability of the native structure of
Authors:Mircea Stefanescu, Marcela Stoia, Oana Stefanescu, and Paul Barvinschi
coordination compounds formed in the redox reaction between NO 3 − (from Fe(III), Ni(II), Zn(II) nitrates) and ethylene glycol (EG) [ 20 ].
This article presents a study on obtaining Ni–Zn ferrite nanoparticles using other polyols: 1,2-propane diol (1
of polyurethane formation between several polyols and isocyanates with dibutyltin
dilaurate (DBTDL) as the curing catalyst, were studied in the bulk state by
differential scanning calorimetry (DSC) using an improved method of interpretation.
The molar enthalpy of urethane formation from secondary hydroxyl groups and
aliphatic isocyanates is 723 kJ mol-1
and for aromatic isocyanates it is 552 kJ mol-1
. In the case of a single second order reaction for aliphatic isocyanates
reaction, activation energy is 705 kJ mol-1
with oxypropylated polyols and 503 kJ mol-1
with Castor oil. For aromatic isocyanates and oxypropylated polyols the activation
energy is higher around 77 kJ mol-1 .
In the case of two
parallel reactions (situation for IPDI and TDI 2-4) best fits are observed
considering two different activation energies.
The low-temperature heat capacity Cp,m of erythritol (C4H10O4, CAS 149-32-6) was precisely measured in the temperature range from 80 to 410 K by means of a small sample automated adiabatic
calorimeter. A solid-liquid phase transition was found at T=390.254 K from the experimental Cp-T curve. The molar enthalpy and entropy of this transition were determined to be 37.92±0.19 kJ mol−1 and 97.17±0.49 J K−1 mol−1, respectively. The thermodynamic functions [HT-H298.15] and [ST-S298.15], were derived from the heat capacity data in the temperature range of 80 to 410 K with an interval of 5 K. The standard
molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined: ΔcHm0(C4H10O4, cr)= −2102.90±1.56 kJ mol−1 and ΔfHm0(C4H10O4, cr)= − 900.29±0.84 kJ mol−1, by means of a precision oxygen-bomb combustion calorimeter at T=298.15 K. DSC and TG measurements were performed to study the thermostability of the compound. The results were in agreement
with those obtained from heat capacity measurements.
Authors:B. Tong, Z. Tan, Q. Shi, Y. Li, and S. Wang
The low-temperature heat capacity Cp,m of sorbitol was precisely measured in the temperature range from 80 to 390 K by means of a small sample automated adiabatic
calorimeter. A solid-liquid phase transition was found at T=369.157 K from the experimental Cp-T curve. The dependence of heat capacity on the temperature was fitted to the following polynomial equations with least square
method. In the temperature range of 80 to 355 K, Cp,m/J K−1 mol−1=170.17+157.75x+128.03x2-146.44x3-335.66x4+177.71x5+306.15x6, x= [(T/K)−217.5]/137.5. In the temperature range of 375 to 390 K, Cp,m/J K−1 mol−1=518.13+3.2819x, x=[(T/K)-382.5]/7.5. The molar enthalpy and entropy of this transition were determined to be 30.35±0.15 kJ mol−1 and 82.22±0.41 J K−1 mol−1 respectively. The thermodynamic functions [HT-H298.15] and [ST-S298.15], were derived from the heat capacity data in the temperature range of 80 to 390 K with an interval of 5 K. DSC and TG measurements
were performed to study the thermostability of the compound. The results were in agreement with those obtained from heat capacity