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

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

The effects of various flame retardants on the combustion of polypropylene: Combining optical diagnostics and pyrolysis fragment analysis

The assessment of the efficacy and mode of action of flame retardants in polymers requires a thorough knowledge of the coupling of the presence of chemical inhibitors with the underlying heat and mass transport processes. In this experimental work, we combine a thermal decomposition analysis with optical combustion diagnostics in different test environments to gain a comprehensive understanding of the relevant sub-processes and demonstrate how this approach provides future opportunities for the research regarding the mode of action of flame retardants. Four different composites of polypropylene (PP) and 10Â wt of selected flame retardants as well as neat PP are prepared. Flame retardants include pentaerythritol spirobis(methylphosphonate) (PSMP), zinc diethylphosphinate (DEPZn), aluminum hydroxide (i.e. aluminum trihydrate, ATH) and ammonium polyphosphate (APP). The released substances in the gas phase are investigated by using thermogravimetric analysis coupled to Fourier-transform infrared spectroscopy (TGA-FTIR), and the burning behavior regarding carbon monoxide concentration and heat release rate (HRR) is studied in cone calorimeter experiments. The ignition and combustion of flame retarded micrometer-sized particles of PP are experimentally investigated in a laminar flat flame burner by means of simultaneous scanning planar laser-induced fluorescence of OH radicals (OH-PLIF) and diffuse back-illumination (DBI) at a repetition rate of 10Â kHz. Particles with gas-phase activity show a decreased normalized OH signal intensity during combustion. A dependency of the dimensionless flame radius on the particle size is found which can be linked to the faster heating and pyrolysis of smaller particles compared to large particles and agglomerations. Eventually, the interaction with an external premixed flame and the subsequent extinction of self-sustaining flames of polymer sticks is investigated using OH-PLIF in an adapted horizontal burning test suited for the application of optical diagnostics. This approach allows to link the findings of investigations encompassing multiple scales, resulting in a thorough understanding of both polymer chemistry and combustion dynamics in flame retarded polymers