1,721,270 research outputs found
Improvement on fire behaviour of water blown PIR-PUR foams: use of an halogen-free flame retardant
No full textSustainability in polyurethanes: old hat or new strategy for future developments?
Full text linkPolyurethanes are facing health and environmental problems related to their chemistry, processing
and end-of-life management. This review summarizes the most recent strategies within the framework
of sustainability and circularity related to the use of polyurethanes with low environmental impact,
focusing on the possibility of performing their synthesis by replacing fossil-based building blocks with
renewable ones, designing vitrimeric polyurethanes, and managing their end-of-life through
enzymatic degradation or biodegradation processes
An experimental method for evaluating isocyanate conversion and trimer formation in polyisocyanate-polyurethane foams
No full textIn this paper, we have developed simple though efficient test method for evaluating both isocyanurate formation and isocyanate degree of conversion using FT-IR analyses and have applied them to polyisocyanurate-polyurethane foams to verify the reliability of the results obtained and evaluate the influence of isocyanate index on both these quantities. We have also characterised the foams from a physical-mechanical point of view and demonstrated that the dimensional stability and compression strength of polymers are closely related to isocyanurate content and therefore to isocyanate index. The results obtained have clearly revealed that an increase in isocyanate index leads to an increase in trimer content and consequently to an improvement of mechanical properties; on the other hand, an increase in the isocyanate index brings about a decrease in isocyanate conversion. Moreover, since isocyanurate content and free isocyanate amount affect the fire behaviour of the foam we will apply the procedure proposed in this article to analyse the influence of both factors on the fire behaviour of such foams; the results of our research will be published in a future work
Halogen-free flame retardants for polymeric foams
No full textThe effectiveness of some mixtures of halogen-free flame retardants (i.e. expandable graphite, triethylphosphate and red phosphor-us) in flame retardancy of polyisocyanurate-polyurethane (PIR-PUR) foams, blown with n-pentane, has been investigated by means of DIN 4102-B2 and oxygen index tests. The thermal stability and mechanical properties of PIR-PUR filled foams have also been considered. The results showed that the introduction of increasing amounts of expandable graphite, into foams containing triethylphosphate or red phosphorus, causes a significant worsening of physical-mechanical properties. The fire behaviour characterisation has demonstrated that the introduction of such flame retardants as fillers leads to a great improvement particularly for foams filled with expandable graphite and triethylphosphate. Also significant improvement has been observed in thermal stability due to the presence of flame retardants
Flame-Retardant Design and Protection for Building Materials
No full textBuilding materials often need to meet fire safety requirements that are set by building and fire codes, and for this to be successfully met, it requires close attention to the tests required by the codes, as well as understanding the material chemistry and end use requirements of the building material. A material that can meet a fire requirement but doesn't have the required mechanical and thermal properties for its end-use application is not a success. This chapter covers building components that require flame retardancy, including some discussion of building codes and standards. Fire protection of specific building materials including roofing and siding, insulation, and structural materials is discussed, including some insight into how to design fire-safe materials for these applications
Influence of Processing Parameters on the Structure of Melt Blended Polyethylene/Organoclay Nanocomposites Produced by a Masterbatch Route
No full textMelt compounding is one of the most used methods to produce thermoplastic-based nanocomposites. The aim of this study is the assessment of the effects of processing set-up and conditions on the structure and properties of low-density polyethylene/organically modifies layered silicate (OMLS) nanocomposites obtained by a two-step process by concentrate masterbatch route. Concentrate masterbatch formulation and dilution have been investigated to correlate processing parameters with final nanocomposites structure by means of morphological and physical characterization. Even if a good dispersion/intercalation occurred regarding concentrate masterbatch, the probability of a further OMLS dispersion during the masterbatch dilution process depends remarkably on the extruder mixing capacity, with important consequences for the industrial application of masterbatch technology in net shape forming processes. POLYM. ENG. SCI., 00:000–000, 2012. a2012 Society of Plastics Engineer
Effect of processing conditions on mechanical and thermal properties of polypropylene nanocomposites
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