RESUMO
The fire performance of epoxy and carbon-fiber-reinforced polymer (CFRP) composites with and without fire retardants (FR) (i.e., ammonium polyphosphate (APP), aluminum trihydroxide (ATH), melamine (MEL), expandable graphite (EG)) was investigated. A design of experiment (DoE) approach was applied to study the single- and multifactorial effects of FR. The fire performance of epoxy and CFRP was evaluated by limiting the oxygen index (LOI) and heat release, which were obtained by limiting the oxygen index test and cone calorimetry. It was found that mixtures of 70 wt.-% epoxy, 24.6 wt.-% of APP, and 5.4 wt.-% MEL resulted in the highest LOI level of 45 within tested groups for epoxy resin and also for CFRP specimens (LOI level of 39). This mixture also resulted in the lowest average heat release rate (HRR180s) of 104 kW·m-2 and a spec. total heat release (THR600s) of 1.14 MJ·m-2·g-1, indicating the importance of balancing spumific and charring agents in intumescent systems and synergy thereof.
RESUMO
In this study, ammonium polyphosphate (APP) and aluminum hydroxide (ALH) with different mass contents were used as fire retardants (FRs) on plant-based natural flax fabric-reinforced polymer (FFRP) composites. Thermogravimetric analysis (TGA), limited oxygen index (LOI), and the Underwriters Laboratories (UL)-94 horizontal and vertical tests were carried out for evaluating the effectiveness of these FR treatments. Flat-coupon tensile test was performed to evaluate the effects of FR treatment on the mechanical properties of the FFRP composites. For both fire retardants, the results showed that the temperature of the thermal decomposition and the LOI values of the composites increased as the FR content increases. Under the UL-94 vertical test, the FFRP composites with 20% and 30% APP (i.e., by mass content of epoxy polymer matrix) were self-extinguished within 30 and 10 s following the removal of the flame without any burning drops, respectively. However, the mechanical tensile tests showed that the APP treated FFRP composites reduced their elastic modulus and strength up to 24% and 18%, respectively. Scanning electronic microscopic (SEM) for morphology examination showed an effective coating of the flax fibres with the FRs, which improved the flame retardancy of the treated composites.
RESUMO
PURPOSE: Sinonasal malignancies are a rare group of cancers often associated with late presentation and poor prognosis. In the past, there was little progress regarding survival rate, and often, multimodal treatment regimens are required. The aim of this study was to evaluate the clinical outcome of perioperative image-adapted brachytherapy (IABT) as part of a multidisciplinary treatment regimen for the therapy of sinonasal cancer. METHODS AND MATERIALS: Since 2006, patients with sinonasal cancer at the University Hospital of Schleswig-Holstein Campus Luebeck, Germany, were offered a multimodal treatment concept including head and neck surgery, perioperative IABT with or without external beam radiation therapy, and chemotherapy. In a retrospective study, such patients were analyzed for survival rate, tumor control, and toxicity of the interdisciplinary treatment. RESULTS: Thirty-five consecutive patients were analyzed. The majority of patients (63%) were treated for a primary tumor and 62% presented with tumor Stages III-IV. The mean follow-up time with IABT was 28 months. Overall survival estimate was 72% after 3 years. Disease-specific survival, disease-free survival, and local control rates were 83%, 63%, and 67%, respectively. On univariate analysis, a significant better disease-free survival rate was found in patients treated for primary, but not recurrent, sinonasal cancer (p = 0.006). The overall treatment toxicities were mainly classified Grade I. CONCLUSIONS: Interdisciplinary perioperative IABT is associated with excellent locoregional control and survival rates. IABT is well tolerated and shows low toxicity. Furthermore, visual acuity can be preserved in advanced cases. The implementation of perioperative IABT into multimodal treatment regimens improves the oncologic outcome.