Thermal stability of gamma-irradiated polyurethane/POSS hybrid materials

Journal of Thermal Analysis and Calorimetry, Dec 2017

In this work, new version: we report essential data on the stability of gamma-irradiated polyurethanes chemically modified by octa(3-hydroxy-3-methylbutylmethylsiloxy) POSS (o-POSS) which varies from 2, 4, 6, 8 to 10 mass%. These hybrid materials were tested by isothermal (190 °C) and nonisothermal (β = 2, 3.7, 5 and 10 K min−1) chemiluminescence, and the thermal stability of gamma-radiation-aged samples was correlated with the change in the nanofiller loading and absorbed dose. The compositions where inorganic phase is less than 6% show an increasing thermal strength as o-POSS concentration enhances. The other samples with higher nanoparticle content present less stability in respect of inferior homologous composition. The nonisothermal chemiluminescence profiles are changing from one type of sample to the other where nanofiller induces different effects. The considerations on mechanistic aspects are discussed, too.

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Thermal stability of gamma-irradiated polyurethane/POSS hybrid materials

Journal of Thermal Analysis and Calorimetry https://doi.org/10.1007/s10973 Thermal stability of gamma-irradiated polyurethane/POSS hybrid materials Traian Zaharescu 0 1 2 Virgil Marinescu 0 1 2 Edyta Hebda 0 1 2 Krzysztof Pielichowski 0 1 2 0 Department of Chemistry and Technology of Polymers, Cracow University of Technology , ul. Warszawska 24, 31-155 Krako ́w , Poland 1 & Krzysztof Pielichowski 2 & Traian Zaharescu In this work, new version: we report essential data on the stability of gamma-irradiated polyurethanes chemically modified by octa(3-hydroxy-3-methylbutylmethylsiloxy) POSS (o-POSS) which varies from 2, 4, 6, 8 to 10 mass%. These hybrid materials were tested by isothermal (190 C) and nonisothermal (b = 2, 3.7, 5 and 10 K min-1) chemiluminescence, and the thermal stability of gamma-radiation-aged samples was correlated with the change in the nanofiller loading and absorbed dose. The compositions where inorganic phase is less than 6% show an increasing thermal strength as o-POSS concentration enhances. The other samples with higher nanoparticle content present less stability in respect of inferior homologous composition. The nonisothermal chemiluminescence profiles are changing from one type of sample to the other where nanofiller induces different effects. The considerations on mechanistic aspects are discussed, too. Polyurethane; POSS; Chemiluminescence; Thermal stability Introduction The hybrid materials are essential in all economical fields where the improved endurance is required. The enlarging knowledge areas of polyhedral oligomeric silsesquioxanes (POSS)-modified polymers have received deep attention [ 1–5 ] because the presence of this inorganic filler allows the manufacture of long-life engineering products. The diversity of polymer materials such as PMMA [ 6 ], silicone [ 7 ], epoxy resins [ 8 ] and polyurethanes [ 9 ] was studied, where POSS filler acts as a compound suitable for new resistant structures. These papers emphasize additive contribution to the polymer functionality. An intimate interaction between POSS nanoparticles and polyurethane structure was previously presented [ 10 ]. Department of Advanced Materials, INCDIE ICPE CA, 313 Splaiul Unirii, 030138 Bucharest, Romania The degradation of polyurethanes has been amply discussed because these materials have several applications in medical wear, chemical engineering, aircraft industry, nuclear areas [ 9, 11, 12 ]. The excellent radiation stability of polyurethanes [ 13 ] and their large processing dose range [ 14 ] recommends them for long-term applications. The degradation of polyurethanes accelerated by their exposure to high-energy radiation [ 14–16 ] occurs somewhat slowly because they show an evident tendency to cross-link [ 17 ]. The chemiluminescence (CL) examination on the thermal stability of polyurethane composite reveals the contribution of bond dissociation and the elimination of carbon dioxide to the evolution of thermal degradation in polyurethane matrices [ 18, 19 ]. The spectroscopic (ATR-FTIR) analysis identified oxygenated products as main degradation products formed during natural and artificial aging of polyurethane foams [20]. The degradation mechanism of polyurethanes and their POSS composites was previously analyzed. The thermal stability study on the degradation of rigid polyurethanes foams modified with polyhedral oligomeric silsesquioxane on whose structure propanediolizobutyl or (3-hydroxy-3methylbutyldimethylsiloxy) moieties were grafted has pointed out the changes in physical and structural features caused by the interaction between polymer matrix and inorganic particles [ 12 ]. However, the studies on the stabilization of polyurethanes are scarcely published [ 9, 12, 21 ]. They underline the delay of oxidative degradation by the additive activities in respect of the scavenging free radicals, the efficient adsorption on particle surface or the penetration of radicals through channels existing in POSS morphology. The telechelic behavior of PU in the presence of modified POSS nanoparticles [ 22 ] confirms the remarkable thermal resistance of these compositions proving the further capacity of material for the oxidation prevention of creating radicals. The proofs on the improved endurance PU/ POSS systems are the results of phase stability investigation over large temperature range (50–400 C) [ 23 ]. In this paper, the stability investigations by chemiluminescence on radiation processes of MDI-based polyurethane modified with octa(3-hydroxy-3methylbutyldimethylsiloxy) polyhedral oligomeric silsesquioxane (o-POSS) are analyzed. Experimental Synthesis materials Hybrid polyurethane/o-POSS materials were synthesized using 4,40-diphenylmethane diisocyanate (MDI, SigmaAldrich), poly(tetramethylene glycol) (Invista), 1,4-butanediol (Sigma-Aldrich) and o-POSS (Hybrid Plastics) (Fig. 1) in a two-step process [ 10 ]. Methods Radiation processing was accomplishe (...truncated)


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Traian Zaharescu, Virgil Marinescu, Edyta Hebda, Krzysztof Pielichowski. Thermal stability of gamma-irradiated polyurethane/POSS hybrid materials, Journal of Thermal Analysis and Calorimetry, 2017, pp. 1-6, DOI: 10.1007/s10973-017-6884-1