Improving the flame-retardant property of bottle-grade PET foam made by reactive foam extrusion

Upcycling of low intrinsic viscosity (IV) poly(ethylene terephthalate) (PET) grades, such as bottle‐ or recycled grades, by a reactive foam extrusion process, provides an appropriate alternative to high pricing, high IV grades commonly used for foaming applications. However, the drawback of bottle‐grade PET foams is its flame retardant (FR) performance. In this study, pyromellitic dianhydride was used as a chain extender to foam bottle‐grade PET. The influence of different FRs, containing halogenated (HFR) and four different phosphorous‐based types, on the processability and final foam properties was investigated. HFR showed better processability to achieve proper foams with fine morphology compared to P‐based FRs, where the FR content was adjusted between 2 and 5 wt%. However, HFR exhibited lower FR performance by cone calorimeter testing compared to the P‐based FRs and the commercial reference foam Kerdyn. Nonetheless, all of the FRs can only improve the time to ignition of the neat PET foams while the other values depend on the specific type of FR. In addition, all FR foams have improved mechanical properties more than twice in comparison to the neat PET foam

Fire behavior of flame retarded sandwich structures containing PET foam cores and epoxy face sheets

Within this work, the investigation on interactions of a phosphorus‐containing flame retardant (FR) DEPAl in epoxy face sheets and five different FRs in the PET‐foam core of a sandwich laminate on the fire behavior is focused. Fourteen different combinations of resin face sheets and PET foam cores are produced by vacuum assisted resin infusion (VARI). The combustion behavior of the sandwich laminates is tested by cone calorimetry. The time to ignition is lowered when a FR resin is used while the subsequent burning behavior is mainly influenced by the PET foam core. In order to evaluate the interactions of the flame retardants in the core and face sheet, a total improvement value (TIV) was set up which compares the performance related to the specific FR combinations. The highest TIV value (76%) indicating positive interactions with DEPAl was observed with a 2‐PSMP‐PET core, the lowest value (−2%) with a DEPZn‐PET core

Flame retardant polyester by combination of organophosphorus compounds and an NOR radical forming agent

Polymer materials with different surface-to-volume ratios require different mechanisms of flame retardants regarding condensed phase and gas phase activity. The flame retardant formulations in poly(ethylene terephthalate) (PET) are investigated regarding a condensed phase and gas phase activity by using thermogravimetric analysis (TGA), TG-mass spectrometry (MS), TG-Fourier transform infrared (FTIR), UL94, cone calorimeter and scanning electron microscopy–energy-dispersive X-ray spectrometer measurements. The flame retardant formulations containing phosphates, phosphonates, and phosphinates as flame retardants are analyzed by using a simultaneous analysis consisting of a differential thermal analysis-TGA device which is in situ coupled to FTIR and MS. All analysis methods show a gas phase activity for the phosphonate (PCO 910), a condensed phase activity for the phosphate (3,9-bis(phenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro-5,5-undecane-3,9-dioxide, (SPDPP) and a mixed condensed and gas phase activity for the new synthesized phosphate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide containing flame retardant 3,9-bis(phenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro-5,5-undecane-3,9-dioxide (SPDPDOM). The fire behavior of PCO 910 can be improved by adding O,O'-Terephthaloyl-bis-N,N'-naphthalimide ester as NOR radical-forming agent (NOR-RF) reaching a total amount of 3 wt % of both active agents for a UL94 V-0 classification in PET

Neue Flammschutzmittel für PET und Aufklärung der Wirkmechanismen

Diese Arbeit beschäftigt sich mit der Synthese von Flammschutzmitteln und der Wirkweise dieser und literaturbekannter Flammschutzmittel in verschiedenen Polymeren. Hierbei wurde der Fokus auf die Gasphase hinsichtlich der Wirkungsweise von Flammschutzmitteln gelegt. Dabei wurden verschiedene, sich ergänzende Methoden verwendet, um die Wirkungsweise zu untersuchen. Mit den daraus erhaltenen Ergebnissen konnten Hinweise auf den vorliegenden Zersetzungsmechanismus erhalten werden

Polyamine sensing by nascent ornithine decarboxylase antizyme stimulates decoding of its mRNA

Polyamines are essential organic polycations with multiple cellular functions relevant for cell division, cancer and ageing(1-3). Regulation of polyamine synthesis is mainly achieved by controlling the activity of ornithine decarboxylase (ODC) through an unusual mechanism involving ODC antizyme(1,4), the binding of which disrupts homodimeric ODC and targets it for ubiquitin-independent degradation by the 26S proteasome(5). Whereas mammals express several antizyme genes(6), we have identified a single orthologue, termed OAZ1, in Saccharomyces cerevisiae(7). Similar to its mammalian counterparts, OAZ1 synthesis is induced with rising intracellular polyamine concentrations, which also inhibit ubiquitin-dependent degradation of the OAZ1 protein(7). Together, these mechanisms contribute to a homeostatic feedback regulation of polyamines(1,7,8). Antizyme synthesis involves a conserved +1 ribosomal frameshifting (RFS) event at an internal STOP codon during decoding of its messenger RNA(6-10). Here we used S. cerevisiae OAZ1 to dissect the enigmatic mechanism underlying polyamine regulation of RFS. In contrast with previous assumptions, we report here that the nascent antizyme polypeptide is the relevant polyamine sensor that operates in cis to negatively regulate upstream RFS on the polysomes, where its own mRNA is being translated. At low polyamine levels, the emerging antizyme polypeptide inhibits completion of its synthesis causing a ribosome pile-up on antizyme mRNA, whereas polyamine binding to nascent antizyme promotes completion of its synthesis. Thus, our study reveals a novel autoregulatory mechanism, in which binding of a small metabolite to a nascent sensor protein stimulates the latter's synthesis co-translationally

Synthesis of novel bisphosphorylimides based on Staudinger reaction

A series of bisphosphorylimides based on the reaction sequence of Atherton-Todd and Staudinger reaction were synthesized. These bisphosphorylimides containing phosphorus in different chemical environments, while the reaction sequence is using mild conditions and more over can be synthesized in an one-pot procedure. The molecular structures were revealed by nuclear magnetic resonance spectroscopy and x-ray crystallography. The stability of the bisphosphorylimides against hydrolysis and thermal influences was tested which allows an initial estimation about the usage as flame retardant

Fire behavior of flame retarded sandwich structures containing PET

Within this work, the investigation on interactions of a phosphorus‐containing flame retardant (FR) DEPAl in epoxy face sheets and five different FRs in the PET‐foam core of a sandwich laminate on the fire behavior is focused. Fourteen different combinations of resin face sheets and PET foam cores are produced by vacuum assisted resin infusion (VARI). The combustion behavior of the sandwich laminates is tested by cone calorimetry. The time to ignition is lowered when a FR resin is used while the subsequent burning behavior is mainly influenced by the PET foam core. In order to evaluate the interactions of the flame retardants in the core and face sheet, a total improvement value (TIV) was set up which compares the performance related to the specific FR combinations. The highest TIV value (76%) indicating positive interactions with DEPAl was observed with a 2‐PSMP‐PET core, the lowest value (−2%) with a DEPZn‐PET core

Phosphorus-Containing Flame Retardants from Biobased Chemicals and Their Application in Polyesters and Epoxy Resins

Phosphorus-containing flame retardants synthesized from renewable resources have had a lot of impact in recent years. This article outlines the synthesis, characterization and evaluation of these compounds in polyesters and epoxy resins. The different approaches used in producing biobased flame retardant polyesters and epoxy resins are reported. While for the polyesters biomass derived compounds usually are phosphorylated and melt blended with the polymer, biobased flame retardants for epoxy resins are directly incorporated into the polymer structure by a using a phosphorylated biobased monomer or curing agent. Evaluating the efficiency of the flame retardant composites is done by discussing results obtained from UL94 vertical burning, limiting oxygen index (LOI) and cone calorimetry tests. The review ends with an outlook on future development trends of biobased flame retardant systems for polyesters and epoxy resins