Comparative evolved gas analyses on thermal degradation of thiourea by coupled TG-FTIR and TG/DTA-MS instruments

Olszewska

2013

Two series of new thermoplastic poly(thiourethane-urethane) elastomers (EPTURs), with different hardsegment content (40-60 wt%), were synthesized by a onestep melt polymerization from poly(oxytetramethylene) diol (PTMO) of M n = 1,000 g mol -1 or poly(hexamethylene carbonate) diol (PHCD) of M n = 860 g mol -1 as a soft segment, hexane-1,6-diyl diisocyanate and (methylenedi-1,4-phenylene)dimethanethiol as a chain extender at the NCO/(OH ? SH) molar ratio of 1. The structures of all the EPTURs were examined by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy and X-ray diffraction analysis. Their thermal behavior was investigated by means of differential scanning calorimetry and thermogravimetric analysis (TG). For the chosen polymers the gaseous products evolved during the decomposition process were analyzed by TG-FTIR. Moreover, physicochemical, adhesive and tensile properties as well as Shore A/D hardness were determined. The resulting highmolecular-mass EPTURs were stable up to 254-262°C, as measured by the temperature of 1 % mass loss. They decomposed in three or four stages. The main decomposition products were carbonyl sulfide, isocyanate, carbon dioxide, aromatic hydrocarbons as well as aliphatic ethers and aldehydes (in PTMO series) and alcohols (in PHCD series). All the polymers showed partially crystalline structures, associated with crystallization of thiourethane hard segments. Their melting temperatures were in the range of 184-186°C. The PTMO series EPTURs exhibited better low-temperature properties (glass-transition temperature in the range of -64 to -44 vs. -26 to -22°C), but poorer tensile strengths (20-28 vs. 37-43 MPa). These EPTURs showed improved adhesive properties in comparison with their polyurethane analogs.

Section: Tg-ftirmentioning

confidence: 99%

Section: Tg-ftirmentioning

confidence: 99%

New thermoplastic poly(thiourethane-urethane) elastomers based on hexane-1,6-diyl diisocyanate (HDI)

Olszewska

2013

“…6, showed that their decomposition was connected with the elimination of carbon dioxide (intensive bands at 2359-2310 cm , characteristic of asymmetric and symmetric C=O stretching vibration [28][29][30][31][32]) and water (bands at *4000-3500 cm -1 and *1800-1300 cm -1 [33]). With the growth of the temperature, the band coming from carbon dioxide decreased, while the one from carbonyl sulfide increased, reaching a maximum at temperature 415°C (for H) and 380°C (for HM) (see Fig.…”

Section: Tgmentioning

confidence: 99%

Aliphatic polycarbonate-based thermoplastic polyurethane elastomers containing diphenyl sulfide units

2016

New thermoplastic polyurethane elastomers (TPUs) were obtained by a one-step melt polyaddition from 30, 45 and 60 mol% aliphatic polycarbonate diol of M n = 2000 g mol -1 (Desmophen Ò C2200, Bayer), 1,1 0 -methanediylbis(4-isocyanatocyclohexane) (HMDI) or 1,6-diisocyanatohexane (HDI) and 2,2 0 -[sulfanediylbis(benzene-1,4-diyloxy)]diethanol (acting as a chain extender). The TPUs were examined by FTIR, UV-Vis, atomic force microscopy, X-ray diffraction analysis, differential scanning calorimetry, thermogravimetry (TG) and TG-FTIR. Moreover, their Shore A/D hardness, tensile, adhesive and optical properties were determined. The obtained TPUs were transparent or opaque high molar mass materials, showing amorphous or partially crystalline structures. The HDI-based TPUs exhibited lower glass-transition temperatures than those based on HMDI (from -35 to -31°C vs. from -20 to 1°C) as well as a higher degree of microphase separation. The TPUs were stable up to 262-272°C, taking into account the temperature of 1 % mass loss, with somewhat higher values shown by those from HDI. They decomposed in two stages. The main volatile products of the hard-segment decomposition were carbon dioxide, water and carbonyl sulfide, while aliphatic ethers, aldehydes and unsaturated alcohols, as well as carbon dioxide, originated from the soft-segment decomposition. The synthesized TPUs, with hardness in the range of 80-90°Sh A, possessed a good tensile strength (33.0-38.7 MPa), similar to that of the commercial biodurable medical grade TPU ChronoFlex Ò AL 80A (37.9 MPa), prepared from aliphatic polycarbonate diol, HMDI and butane-1,4-diol.

“…In turn, spectrum from the third stage (T max at 450°C) additionally revealed bands typical of carbonyl sulfide (at 2072 and 2047 cm -1 , characteristic of asymmetric and symmetric C=O stretching vibration [25][26][27]). …”

Section: Tgmentioning

confidence: 99%

The effect of chain extender structure on the properties of new thermoplastic poly(carbonate–urethane)s derived from MDI

Pikus

2016

Two series of high-molar-mass thermoplastic poly(carbonate-urethane)s (PCURs) were synthesized from nonconventional sulfur-containing chain extenders, i.e., 2,2 0 -[sulfanediylbis(benzene-1,4-diyloxy)]diethanol (diol SE) and 2,2 0 -[methanediylbis(benzene-1,4-diylmethanediylsulfanediyl)]diethanol (diol ME), 1,1 0 -methanediylbis(4-isocyanatobenzene) and 30, 45 and 60 mol% aliphatic polycarbonate diol of M n = 2000 g mol -1 (Desmophen Ò C2200, Bayer) via a one-step melt polyaddition. The PCURs were investigated by FTIR, UV-Vis, atomic force microscopy, X-ray diffraction analysis, differential scanning calorimetry, thermogravimetry (TG) and TG-FTIR. Moreover, their Shore A/D hardness, tensile, adhesive and optical properties were determined. The obtained PCURs were transparent or opaque elastomers, possessing amorphous or partially crystalline structures. The polymers based on diol ME showed lower glass transition temperatures (-9 to (-8) vs. -7 to 20°C) and better microphase separation. All the PCURs exhibited a relatively good thermal stability. Their temperature of 1 % mass loss was within the range of 284-292°C with somewhat higher values shown by those obtained from diol ME. The PCURs decomposed in two (from diol ME) or three (from diol SE) stages, and for both types of polymers, the main decomposition occurred at the first stage. All the PCURs based on diol SE exhibited higher tensile strength (33.5-41.9 vs. 27.0-31.5 MPa), but smaller elongation at break (300-400 vs. 450-550 %) than polymers derived from diol ME. Somewhat better adhesive properties and a slightly higher refractive index were found for polymer based on diol ME with two sulfur atoms.