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)