Shedding new light on polyurethane degradation: Assessing foams condition in design objects

Sá, Susana França de; Ferreira, Joana Lia; Cardoso, Isabel Pombo; Macedo, Rita; Ramos, A.M.

doi:10.1016/j.polymdegradstab.2017.08.028

Cited by 29 publications

(17 citation statements)

References 36 publications

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“…For the foams with 10% concentration of the mineral filler, a degradation peak has been observed around 200°C, which is attributed to the presence of unreacted raw materials owing to an incomplete reaction of the polyol with the polyisocyanate and the deterioration in the structure of the RPUF. Amount of residue produced was also found to be increased on increasing the filler concentration in RPUF, which supports early extinguish of the flame in real fire condition …”

Section: Resultssupporting

confidence: 65%

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Investigation on flammability of rigid polyurethane foam‐mineral fillers composite

2019

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Summary This study investigates the incorporation of castor oil–based rigid polyurethane foam with mineral fillers feldspar or kaolinite clay in order to enhance the mechanical, thermal, and flame retardant properties. Influence of mineral fillers on the mechanical strength was characterized by compressive strength and flexural strength measurement. Thermogravimetric analysis (TGA) was performed to diagnose the changes in thermal properties, while cone calorimeter test was performed to ascertain the flame retardancy of the mineral filler–incorporated rigid polyurethane foam composites. Results showed that the foams incorporated with mineral filler demonstrated up to 182% increase in compressive strength and 351% increase in flexural strength. Thermal stability of these composite foams was also found to be enhanced on the incorporation of kaolinite clay filler with an increase in 5% weight loss temperature (T5%) from 192°C to 260°C. Furthermore, peak heat release rate (PHRR), total heat release (THR), smoke production rate (SPR), and total smoke release (TSR) were also found to decreased on the incorporation of mineral filler in the rigid polyurethane foam. So mineral fillers are ascertained as a potential filler to enhance the mechanical, thermal, and flame retardant behaviors of bio‐based rigid polyurethane foam composites.

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Section: Resultssupporting

confidence: 65%

“…Amount of residue produced was also found to be increased on increasing the filler concentration in RPUF, which supports early extinguish of the flame in real fire condition. 38 Table 4.…”

Section: Thermogravimetric Analysismentioning

confidence: 99%

Investigation on flammability of rigid polyurethane foam‐mineral fillers composite

2019

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“…Auto-fluorescence was observed when samples were illuminated with blue-violet light (λ = 395–440 nm), Figure 10 . Studies that use fluorescence microscopy as a tool to follow polymer degradation are scarce [ 70 ] and none was found that specifically follows PMMA photodegradation. The development of fluorescence in artificially aged PMMA samples was detected by fluorescence spectroscopy by Dickens and co-workers [ 28 ], with a maximum excitation at ~375 nm and emission at 480 nm, attributed by the authors to the formation of carbonyl groups in α-diketones and α,β unsaturated aldehydes.…”

Section: Resultsmentioning

confidence: 99%

Characterization and Long-Term Stability of Historical PMMA: Impact of Additives and Acrylic Sheet Industrial Production Processes

et al. 2020

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This work aims at understanding the influence of the production processes and materials in the properties and long term behavior of acrylic sheet, i.e., poly(methyl methacrylate) (PMMA), a material generally considered very stable in museum collections. A comparative study was conducted in samples from cast acrylic sheets produced in the early 2000s, from which manufacturing details were known, and samples provided by the artist Lourdes Castro from acrylic sheets she had bought in the 1960s. Transparent and red opaque cast acrylic samples, containing cadmium red pigment, were used. All samples were artificially aged in a solarbox with irradiation λ > 300 nm for a total period of 8000 h, and alterations were followed by a multi-analytical approach which included Raman, infrared (FTIR-ATR) and UV-Vis spectroscopies; gravimetry; size exclusion chromatography (SEC); thermogravimetry (TGA); micro-indentation; colorimetry; and optical microscopy. Not all cast PMMA sheets presented similar stabilities. We have concluded that the production processes (which may include the polymerization conditions, the organic additives and the origin of the monomer) play a more important role in the properties and long-term behavior of these acrylic sheets than the presence of cadmium red and/or the age of the material.

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“…40 These water to water H bonds could break upon compression of the foam, allowing for chain slippage. França de Sá et al 27 propose that the elimination of some bonded interactions would enable the penetration of further water molecules as well as the interaction of oxidation products into the free space between the hard segment chains, leading to the formation of new Hbonding interactions between these compounds and the urea group. Because the relative humidity inside both environmental chambers used was close to zero, permanent H-bond disruption or replacement would be unlikely, as confirmed through our FTIR analysis of the post-cycled samples (see Figure 8B).…”

Section: Discussionmentioning

confidence: 99%

Effects of thermal and mechanical cyclic loads on polyurethane pre‐insulated pipes

Doyle

Weidlich

2020

Fatigue Fract Eng Mat Struct

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District heating (DH) pre-insulated pipes are a sandwich assembly composed by a steel heat service pipe, polyurethane (PU) foam and polyethylene casing. The foam acts as bond between the steel pipe and casing. The application has high constraints for the foam, as it is subjected to cyclic multiaxial stresses, high cyclic temperatures and long expected service life. In this study, we evaluate if and how cyclic loads affect the shear strength, shear modulus, toughness and failure behaviour of the PU foam in DH pipes sandwich assembly compared with unaged reference samples. We have found that the simultaneous application of mechanical and thermal loads weakens the strength and increases the stiffness of the foam and that this change is not caused by degradation of the molecular structure. Crack initiation and propagation along the pipe samples follow a very consistent pattern between samples, with cracks initiating in Mode II and propagating in Mode I. The consistent axial displacement of approximately 2 cm from each other suggests the formation of strain localizations.

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Shedding new light on polyurethane degradation: Assessing foams condition in design objects

Cited by 29 publications

References 36 publications

Investigation on flammability of rigid polyurethane foam‐mineral fillers composite

Investigation on flammability of rigid polyurethane foam‐mineral fillers composite

Characterization and Long-Term Stability of Historical PMMA: Impact of Additives and Acrylic Sheet Industrial Production Processes

Effects of thermal and mechanical cyclic loads on polyurethane pre‐insulated pipes

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