Bio-based flame retardant for sustainable building materials

As new promising alternatives, novel bio-based materials are already developed to apply in construction sectors due to biodegradability, low toxicity, sustainability, renewability, and acceptable general properties. However, their flammability and need to guarantee a low fire risk in the constructions is also an essential factor to restrict their further application. This thesis focused on investigation of bio-based material with good flame-retardant performance and corresponding flame-retardant mechanism. The detailed investigation was developed by following stages: synthesis of bio-based flame retardant and its application in PLA; effect of bio-based flame retardant on the fire resistance and other properties of natural fiber reinforced PLA. Finally, the smouldering and combustion performances of the bio-based thermal insulation material made from natural fiber were studied as well. 1) On basis of bio-based concept, PA and THAM were selected as raw material to synthesize a novel flame retardant and the chemical structure was confirmed via some characterizations. Afterwards, this synthetic product PA-THAM was employed as an efficient flame retardant to PLA by melt mixing. This binary system showed an improvement in flame retardancy, which was achieved by a combination of heat transfer effect, slight dilution and barrier action. For example, only 3 wt% loading of PA-THAM imparted PLA-based biocomposite LOI value of 25.8% and UL 94 V-0 level, as well as a significant self-extinguishing ability was observed. Besides, the molten viscosity of biocomposite also demonstrated more reduction compared with neat PLA due to the lubrication of PA-THAM, while there was little change in the mechanical properties. 2) PA-THAM and corn pith cellulose (OCC) were combined via in-situ modification and used to prepare a PLA-based biocomposite. After OCC was modified by PA-THAM successfully, which was proved by SEM/ EDS, FTIR, and TGA, the effect of PA-THAM on thermal stability and fire behaviors of PLA-based composite were also investigated accordingly. 5 phr addition of PA-THAM enabled this natural fiber reinforced polymer biocomposite (NPC) to illustrate a 50 °C higher temperature at maximum degradation rate than control sample without additive, and an improvement was also obtained in flame retardant properties with an increase of LOI value, a reduction of PHRR, and more char residue. The predominant flame-retardant mechanism focused on the synergistic effect of PA-THAM and OCC that occurred in condensed phase. Besides, the same level introduction of PA-THAM improved the interfacial affinity between PLA and OCC that maintained good mechanical properties as well. 3) A bio-based thermal insulation material was made from corn pith cellulose, alginate, and bio-efficient flame retardants. After introducing these bio-based additives, the smouldering and flaming combustion behaviors were improved significantly. Compared with the reference sample, thermal insulation particleboard with 8 wt% loading of a mixture of PA-THAM and a sodium borate salt (DOT) increased the initial temperature of smoldering ignition by 70 ºC, and meanwhile, the value of PHRR in flaming combustion decreased by 25.5%. Furthermore, the thermal conductivity was hardly affected, while the temperature at which the maximum thermal degradation occured increased. The correlative flame retardant mechanism was attributed to a synergistic effect from both flame retardants, which promoted a formation of more stable charring layer at initial stage.Los materiales de base biológica ofrecen una alternativa prometedora para aplicaciones en el sector de la construcción, debido a que se trata de materiales biodegradables, renovables y de baja toxicidad. Sin embargo, su capacidad de inflamar y la necesidad de mantener un bajo riesgo frente a incendios en los edificios es un factor esencial para restringir su posterior aplicación. Esta tesis se ha centrado en el desarrollo de materiales de base biológica con buen comportamiento frente al fuego y la investigación de los mecanismos de los retardantes de llama involucrados. La investigación se desarrolló en tres etapas que se detallan a continuación. 1) Partiendo del concepto de base biológica, se seleccionaron PA y THAM como materias primas para sintetizar un nuevo retardante de llama y la estructura química se confirmó mediante la caracterización del compuesto resultante. Posteriormente, este producto sintético PA-THAM se empleó como un retardante de llama eficiente para PLA mediante mezcla fundida. Este sistema binario mostró una mejora en la resistencia al fuego, que se logró mediante una combinación de los efectos de transferencia de calor, ligera dilución y acción barrera. Por ejemplo, con sólo un 3% en peso de carga de PA-THAM se logró un valor de LOI de 25,8% del compuesto de PLA y un nivel UL 94 V-0, así como una capacidad de autoextinción significativa. Además, la viscosidad fundida del biocompuesto también se redujo en relación a la del PLA puro debido a la lubricación ejercida por el PA-THAM. Por otro lado, la adición del retardante ocasionó pocos cambios en las propiedades mecánicas. 2) El retardante basado en PA-THAM y la fracción fina obtenida triturando la médula de maíz (OCC) se combinaron mediante modificación in situ y se usaron para preparar un biocompuesto basado en PLA. La médula de maíz fue modificada con éxito con el PA-THAM, la cual cosa se demostró por SEM / EDS, FTIR y TGA, el efecto de PA-THAM sobre la estabilidad térmica y el comportamiento al fuego del material compuesto a base de PLA también fueron investigados. La adición de 5 phr de PA-THAM permitió a este biocompuesto reforzado con fibras naturales (NPC) alcanzar una temperatura 50 °C más alta en el punto de degradación máximo comparado con la muestra de control sin aditivo. También se obtuvo una mejora en el comportamiento al fuego con un aumento del valor de LOI, una reducción del pico máximo del ritmo de liberación de calor (PHRR), y una mayor formación de residuo carbonizado. El mecanismo ignífugo predominante se centró en el efecto sinérgico del PA-THAM y la OCC que ocurrió en la fase condensada. Además, el mismo nivel de introducción de PA-THAM mejoró la afinidad interfacial entre PLA y OCC que también mantuvo buenas propiedades mecánicas. 3) Se prepararon muestras de un material de aislamiento térmico de base biológica a partir de médula de maíz, alginato y retardantes de llama de origen biológico. La adición del retardante de llama de base biológica logró mejorar significativamente el comportamiento al fuego, y el fenómeno de combustión sin llama (smouldering). En comparación con la muestra de referencia, el panel aislante con una carga de 8% en peso de una mezcla de PA-THAM y una sal de borato de sodio (DOT) aumentó la temperatura inicial a la que se produce la combustión sin llama en 70 ºC y, permitió reducir el valor de PHRR en un 25.5%. Además, la conductividad térmica apenas se vio afectada, mientras que la temperatura a la que se produce el valor máximo de degradación térmica aumentó notablemente. El análisis del mecanismo de acción de los retardantes reveló la existencia de un efecto sinérgico de ambos retardantes de llama, que promovió la formación de una capa de carbonización más estable en la etapa inicial

Bio-based flame retardant for sustainable building materials

As new promising alternatives, novel bio-based materials are already developed to apply in construction sectors due to biodegradability, low toxicity, sustainability, renewability, and acceptable general properties. However, their flammability and need to guarantee a low fire risk in the constructions is also an essential factor to restrict their further application. This thesis focused on investigation of bio-based material with good flame-retardant performance and corresponding flame-retardant mechanism. The detailed investigation was developed by following stages: synthesis of bio-based flame retardant and its application in PLA; effect of bio-based flame retardant on the fire resistance and other properties of natural fiber reinforced PLA. Finally, the smouldering and combustion performances of the bio-based thermal insulation material made from natural fiber were studied as well. 1) On basis of bio-based concept, PA and THAM were selected as raw material to synthesize a novel flame retardant and the chemical structure was confirmed via some characterizations. Afterwards, this synthetic product PA-THAM was employed as an efficient flame retardant to PLA by melt mixing. This binary system showed an improvement in flame retardancy, which was achieved by a combination of heat transfer effect, slight dilution and barrier action. For example, only 3 wt% loading of PA-THAM imparted PLA-based biocomposite LOI value of 25.8% and UL 94 V-0 level, as well as a significant self-extinguishing ability was observed. Besides, the molten viscosity of biocomposite also demonstrated more reduction compared with neat PLA due to the lubrication of PA-THAM, while there was little change in the mechanical properties. 2) PA-THAM and corn pith cellulose (OCC) were combined via in-situ modification and used to prepare a PLA-based biocomposite. After OCC was modified by PA-THAM successfully, which was proved by SEM/ EDS, FTIR, and TGA, the effect of PA-THAM on thermal stability and fire behaviors of PLA-based composite were also investigated accordingly. 5 phr addition of PA-THAM enabled this natural fiber reinforced polymer biocomposite (NPC) to illustrate a 50 °C higher temperature at maximum degradation rate than control sample without additive, and an improvement was also obtained in flame retardant properties with an increase of LOI value, a reduction of PHRR, and more char residue. The predominant flame-retardant mechanism focused on the synergistic effect of PA-THAM and OCC that occurred in condensed phase. Besides, the same level introduction of PA-THAM improved the interfacial affinity between PLA and OCC that maintained good mechanical properties as well. 3) A bio-based thermal insulation material was made from corn pith cellulose, alginate, and bio-efficient flame retardants. After introducing these bio-based additives, the smouldering and flaming combustion behaviors were improved significantly. Compared with the reference sample, thermal insulation particleboard with 8 wt% loading of a mixture of PA-THAM and a sodium borate salt (DOT) increased the initial temperature of smoldering ignition by 70 ºC, and meanwhile, the value of PHRR in flaming combustion decreased by 25.5%. Furthermore, the thermal conductivity was hardly affected, while the temperature at which the maximum thermal degradation occured increased. The correlative flame retardant mechanism was attributed to a synergistic effect from both flame retardants, which promoted a formation of more stable charring layer at initial stage.Los materiales de base biológica ofrecen una alternativa prometedora para aplicaciones en el sector de la construcción, debido a que se trata de materiales biodegradables, renovables y de baja toxicidad. Sin embargo, su capacidad de inflamar y la necesidad de mantener un bajo riesgo frente a incendios en los edificios es un factor esencial para restringir su posterior aplicación. Esta tesis se ha centrado en el desarrollo de materiales de base biológica con buen comportamiento frente al fuego y la investigación de los mecanismos de los retardantes de llama involucrados. La investigación se desarrolló en tres etapas que se detallan a continuación. 1) Partiendo del concepto de base biológica, se seleccionaron PA y THAM como materias primas para sintetizar un nuevo retardante de llama y la estructura química se confirmó mediante la caracterización del compuesto resultante. Posteriormente, este producto sintético PA-THAM se empleó como un retardante de llama eficiente para PLA mediante mezcla fundida. Este sistema binario mostró una mejora en la resistencia al fuego, que se logró mediante una combinación de los efectos de transferencia de calor, ligera dilución y acción barrera. Por ejemplo, con sólo un 3% en peso de carga de PA-THAM se logró un valor de LOI de 25,8% del compuesto de PLA y un nivel UL 94 V-0, así como una capacidad de autoextinción significativa. Además, la viscosidad fundida del biocompuesto también se redujo en relación a la del PLA puro debido a la lubricación ejercida por el PA-THAM. Por otro lado, la adición del retardante ocasionó pocos cambios en las propiedades mecánicas. 2) El retardante basado en PA-THAM y la fracción fina obtenida triturando la médula de maíz (OCC) se combinaron mediante modificación in situ y se usaron para preparar un biocompuesto basado en PLA. La médula de maíz fue modificada con éxito con el PA-THAM, la cual cosa se demostró por SEM / EDS, FTIR y TGA, el efecto de PA-THAM sobre la estabilidad térmica y el comportamiento al fuego del material compuesto a base de PLA también fueron investigados. La adición de 5 phr de PA-THAM permitió a este biocompuesto reforzado con fibras naturales (NPC) alcanzar una temperatura 50 °C más alta en el punto de degradación máximo comparado con la muestra de control sin aditivo. También se obtuvo una mejora en el comportamiento al fuego con un aumento del valor de LOI, una reducción del pico máximo del ritmo de liberación de calor (PHRR), y una mayor formación de residuo carbonizado. El mecanismo ignífugo predominante se centró en el efecto sinérgico del PA-THAM y la OCC que ocurrió en la fase condensada. Además, el mismo nivel de introducción de PA-THAM mejoró la afinidad interfacial entre PLA y OCC que también mantuvo buenas propiedades mecánicas. 3) Se prepararon muestras de un material de aislamiento térmico de base biológica a partir de médula de maíz, alginato y retardantes de llama de origen biológico. La adición del retardante de llama de base biológica logró mejorar significativamente el comportamiento al fuego, y el fenómeno de combustión sin llama (smouldering). En comparación con la muestra de referencia, el panel aislante con una carga de 8% en peso de una mezcla de PA-THAM y una sal de borato de sodio (DOT) aumentó la temperatura inicial a la que se produce la combustión sin llama en 70 ºC y, permitió reducir el valor de PHRR en un 25.5%. Además, la conductividad térmica apenas se vio afectada, mientras que la temperatura a la que se produce el valor máximo de degradación térmica aumentó notablemente. El análisis del mecanismo de acción de los retardantes reveló la existencia de un efecto sinérgico de ambos retardantes de llama, que promovió la formación de una capa de carbonización más estable en la etapa inicial.Postprint (published version

Nurses’ knowledge on phlebotomy in tertiary hospitals in China: a cross-sectional multicentric survey

Introduction: In China, phlebotomy practice is mostly executed by nurses instead of phlebotomists. Our hypothesis was that these nurses may lack of knowledge on phlebotomy, especially factors influencing quality of blood samples. This study aims to assess the overall nurses’ knowledge on phlebotomy to provide reference for improving blood sampling practice in China. Materials and methods: A survey was conducted involving nurses from 4 regions and 13 hospitals in China. A phlebotomy knowledge questionnaire was designed based on the Clinical and Laboratory Standards Institute H3-A6 guidelines, combining with the situations in China. Descriptive analysis and binary logistic regression analysis were used to analyze the knowledge level and its influencing factors. Results: A total of 3400 questionnaires were distributed and 3077 valid questionnaires were returned, with an effective return rate of 90.5%. The correct rates of patient identification, hand sanitization, patient assessment, tube mixing time, needle disposing location and tube labelling were greater than 90%. However, the correct rates of order of draw (15.5%), definition of an inversion (22.5%), time to release tourniquet (18.5%) and time to change tube (28.5%) were relatively low. Binary logistic regression analysis showed that the correct rates of the aforementioned four questions were mainly related to the regional distribution of the hospitals (P < 0.001). Conclusions: The knowledge level on phlebotomy among Chinese nurses was found unsatisfactory in some areas. An education program on phlebotomy should be developed for Chinese nurses to improve the consistency among different regions and to enhance nurse’s knowledge level on phlebotomy

Bio-based materials for fire-retardant application in construction products: a review

Bio-based materials are showing great potential to be widely used in construction industry, while reducing fire risk and improving fire resistance of these alternatives also become a major concern due to their inherent flammability. Initially, this review introduces three common bio-based construction materials, including biopolymer-based materials, wood-based materials, and crop-based materials, and their fire behaviors in flaming and smoldering combustion scenarios, accompanied with some typical flame-retardant mechanisms. Sequentially, the recent achievements in improving fire resistance are mainly exhibited in detail for each kind of bio-based materials. There are numerous reports for biopolymer-based flame-retardant materials with mature flame-retardant methodology. With regard to wood-based flame-retardant materials, different criteria and methodologies are needed to evaluate the flame-retardant properties. Meanwhile, in the case of crop-based insulation materials is essential to carefully consider the fire behavior, both in flaming and smoldering combustions, and not only focus on their thermal performance. In the final section, based on the requirements of fire safety and practicality for construction materials, bio-based alternatives with excellent good fire resistance and practical performance are summarized to be a promising way to meet future challengesPeer ReviewedPostprint (author's final draft

Effect of oxidized wood flour as functional filler on the mechanical, thermal and flame-retardant properties of polylactide biocomposites

Based on the biodegradable material-polyethylene glycol (PEG)-as the plasticizer, oxidized wood flour (OWF) as the charring agent for polylactide (PLA), a series flame-retardant PLA biocomposites were prepared via melt-compounding and hot-compression. The effect of OWF on the thermal, mechanical and flame retardant properties of biocomposites was investigated systemically. We have found that after the incorporation of PEG and OWF with 10¿wt% into PLA, the biocomposite showed higher tensile elongation than pure PLA. Furthermore, the presence of OWF and ammonium polyphosphate (APP) imparted the biocomposite good flame-retardant performance, shown a remarkable reduction on the peak of heat release rate (PHRR), improved LOI value and passed UL94 V-0 rating. Moreover, Scanning electron microscopy-energy dispersive spectra (SEM/EDS) and thermogravimetric analysis coupled with infrared spectrometer (TG-FTIR) were also performed to understand the flame retardant mechanism. These results proved that OWF could be as new functional filler for polymer composites to further improve their flame retardancy.Peer ReviewedPostprint (published version

Corrigendum to: Nurses’ knowledge on phlebotomy in tertiary hospitals in China: a cross-sectional multicentric survey

This is a correction of Biochemia Medica 2018;28(1):010703. DOI: https://doi.org/10.11613/ BM.2018.01070

Bio-based flame retardant for sustainable building materials

As new promising alternatives, novel bio-based materials are already developed to apply in construction sectors due to biodegradability, low toxicity, sustainability, renewability, and acceptable general properties. However, their flammability and need to guarantee a low fire risk in the constructions is also an essential factor to restrict their further application. This thesis focused on investigation of bio-based material with good flame-retardant performance and corresponding flame-retardant mechanism. The detailed investigation was developed by following stages: synthesis of bio-based flame retardant and its application in PLA; effect of bio-based flame retardant on the fire resistance and other properties of natural fiber reinforced PLA. Finally, the smouldering and combustion performances of the bio-based thermal insulation material made from natural fiber were studied as well. 1) On basis of bio-based concept, PA and THAM were selected as raw material to synthesize a novel flame retardant and the chemical structure was confirmed via some characterizations. Afterwards, this synthetic product PA-THAM was employed as an efficient flame retardant to PLA by melt mixing. This binary system showed an improvement in flame retardancy, which was achieved by a combination of heat transfer effect, slight dilution and barrier action. For example, only 3 wt% loading of PA-THAM imparted PLA-based biocomposite LOI value of 25.8% and UL 94 V-0 level, as well as a significant self-extinguishing ability was observed. Besides, the molten viscosity of biocomposite also demonstrated more reduction compared with neat PLA due to the lubrication of PA-THAM, while there was little change in the mechanical properties. 2) PA-THAM and corn pith cellulose (OCC) were combined via in-situ modification and used to prepare a PLA-based biocomposite. After OCC was modified by PA-THAM successfully, which was proved by SEM/ EDS, FTIR, and TGA, the effect of PA-THAM on thermal stability and fire behaviors of PLA-based composite were also investigated accordingly. 5 phr addition of PA-THAM enabled this natural fiber reinforced polymer biocomposite (NPC) to illustrate a 50 °C higher temperature at maximum degradation rate than control sample without additive, and an improvement was also obtained in flame retardant properties with an increase of LOI value, a reduction of PHRR, and more char residue. The predominant flame-retardant mechanism focused on the synergistic effect of PA-THAM and OCC that occurred in condensed phase. Besides, the same level introduction of PA-THAM improved the interfacial affinity between PLA and OCC that maintained good mechanical properties as well. 3) A bio-based thermal insulation material was made from corn pith cellulose, alginate, and bio-efficient flame retardants. After introducing these bio-based additives, the smouldering and flaming combustion behaviors were improved significantly. Compared with the reference sample, thermal insulation particleboard with 8 wt% loading of a mixture of PA-THAM and a sodium borate salt (DOT) increased the initial temperature of smoldering ignition by 70 ºC, and meanwhile, the value of PHRR in flaming combustion decreased by 25.5%. Furthermore, the thermal conductivity was hardly affected, while the temperature at which the maximum thermal degradation occured increased. The correlative flame retardant mechanism was attributed to a synergistic effect from both flame retardants, which promoted a formation of more stable charring layer at initial stage.Los materiales de base biológica ofrecen una alternativa prometedora para aplicaciones en el sector de la construcción, debido a que se trata de materiales biodegradables, renovables y de baja toxicidad. Sin embargo, su capacidad de inflamar y la necesidad de mantener un bajo riesgo frente a incendios en los edificios es un factor esencial para restringir su posterior aplicación. Esta tesis se ha centrado en el desarrollo de materiales de base biológica con buen comportamiento frente al fuego y la investigación de los mecanismos de los retardantes de llama involucrados. La investigación se desarrolló en tres etapas que se detallan a continuación. 1) Partiendo del concepto de base biológica, se seleccionaron PA y THAM como materias primas para sintetizar un nuevo retardante de llama y la estructura química se confirmó mediante la caracterización del compuesto resultante. Posteriormente, este producto sintético PA-THAM se empleó como un retardante de llama eficiente para PLA mediante mezcla fundida. Este sistema binario mostró una mejora en la resistencia al fuego, que se logró mediante una combinación de los efectos de transferencia de calor, ligera dilución y acción barrera. Por ejemplo, con sólo un 3% en peso de carga de PA-THAM se logró un valor de LOI de 25,8% del compuesto de PLA y un nivel UL 94 V-0, así como una capacidad de autoextinción significativa. Además, la viscosidad fundida del biocompuesto también se redujo en relación a la del PLA puro debido a la lubricación ejercida por el PA-THAM. Por otro lado, la adición del retardante ocasionó pocos cambios en las propiedades mecánicas. 2) El retardante basado en PA-THAM y la fracción fina obtenida triturando la médula de maíz (OCC) se combinaron mediante modificación in situ y se usaron para preparar un biocompuesto basado en PLA. La médula de maíz fue modificada con éxito con el PA-THAM, la cual cosa se demostró por SEM / EDS, FTIR y TGA, el efecto de PA-THAM sobre la estabilidad térmica y el comportamiento al fuego del material compuesto a base de PLA también fueron investigados. La adición de 5 phr de PA-THAM permitió a este biocompuesto reforzado con fibras naturales (NPC) alcanzar una temperatura 50 °C más alta en el punto de degradación máximo comparado con la muestra de control sin aditivo. También se obtuvo una mejora en el comportamiento al fuego con un aumento del valor de LOI, una reducción del pico máximo del ritmo de liberación de calor (PHRR), y una mayor formación de residuo carbonizado. El mecanismo ignífugo predominante se centró en el efecto sinérgico del PA-THAM y la OCC que ocurrió en la fase condensada. Además, el mismo nivel de introducción de PA-THAM mejoró la afinidad interfacial entre PLA y OCC que también mantuvo buenas propiedades mecánicas. 3) Se prepararon muestras de un material de aislamiento térmico de base biológica a partir de médula de maíz, alginato y retardantes de llama de origen biológico. La adición del retardante de llama de base biológica logró mejorar significativamente el comportamiento al fuego, y el fenómeno de combustión sin llama (smouldering). En comparación con la muestra de referencia, el panel aislante con una carga de 8% en peso de una mezcla de PA-THAM y una sal de borato de sodio (DOT) aumentó la temperatura inicial a la que se produce la combustión sin llama en 70 ºC y, permitió reducir el valor de PHRR en un 25.5%. Además, la conductividad térmica apenas se vio afectada, mientras que la temperatura a la que se produce el valor máximo de degradación térmica aumentó notablemente. El análisis del mecanismo de acción de los retardantes reveló la existencia de un efecto sinérgico de ambos retardantes de llama, que promovió la formación de una capa de carbonización más estable en la etapa inicial

Bio-based flame retardant for sustainable building materials

As new promising alternatives, novel bio-based materials are already developed to apply in construction sectors due to biodegradability, low toxicity, sustainability, renewability, and acceptable general properties. However, their flammability and need to guarantee a low fire risk in the constructions is also an essential factor to restrict their further application. This thesis focused on investigation of bio-based material with good flame-retardant performance and corresponding flame-retardant mechanism. The detailed investigation was developed by following stages: synthesis of bio-based flame retardant and its application in PLA; effect of bio-based flame retardant on the fire resistance and other properties of natural fiber reinforced PLA. Finally, the smouldering and combustion performances of the bio-based thermal insulation material made from natural fiber were studied as well. 1) On basis of bio-based concept, PA and THAM were selected as raw material to synthesize a novel flame retardant and the chemical structure was confirmed via some characterizations. Afterwards, this synthetic product PA-THAM was employed as an efficient flame retardant to PLA by melt mixing. This binary system showed an improvement in flame retardancy, which was achieved by a combination of heat transfer effect, slight dilution and barrier action. For example, only 3 wt% loading of PA-THAM imparted PLA-based biocomposite LOI value of 25.8% and UL 94 V-0 level, as well as a significant self-extinguishing ability was observed. Besides, the molten viscosity of biocomposite also demonstrated more reduction compared with neat PLA due to the lubrication of PA-THAM, while there was little change in the mechanical properties. 2) PA-THAM and corn pith cellulose (OCC) were combined via in-situ modification and used to prepare a PLA-based biocomposite. After OCC was modified by PA-THAM successfully, which was proved by SEM/ EDS, FTIR, and TGA, the effect of PA-THAM on thermal stability and fire behaviors of PLA-based composite were also investigated accordingly. 5 phr addition of PA-THAM enabled this natural fiber reinforced polymer biocomposite (NPC) to illustrate a 50 °C higher temperature at maximum degradation rate than control sample without additive, and an improvement was also obtained in flame retardant properties with an increase of LOI value, a reduction of PHRR, and more char residue. The predominant flame-retardant mechanism focused on the synergistic effect of PA-THAM and OCC that occurred in condensed phase. Besides, the same level introduction of PA-THAM improved the interfacial affinity between PLA and OCC that maintained good mechanical properties as well. 3) A bio-based thermal insulation material was made from corn pith cellulose, alginate, and bio-efficient flame retardants. After introducing these bio-based additives, the smouldering and flaming combustion behaviors were improved significantly. Compared with the reference sample, thermal insulation particleboard with 8 wt% loading of a mixture of PA-THAM and a sodium borate salt (DOT) increased the initial temperature of smoldering ignition by 70 ºC, and meanwhile, the value of PHRR in flaming combustion decreased by 25.5%. Furthermore, the thermal conductivity was hardly affected, while the temperature at which the maximum thermal degradation occured increased. The correlative flame retardant mechanism was attributed to a synergistic effect from both flame retardants, which promoted a formation of more stable charring layer at initial stage.Los materiales de base biológica ofrecen una alternativa prometedora para aplicaciones en el sector de la construcción, debido a que se trata de materiales biodegradables, renovables y de baja toxicidad. Sin embargo, su capacidad de inflamar y la necesidad de mantener un bajo riesgo frente a incendios en los edificios es un factor esencial para restringir su posterior aplicación. Esta tesis se ha centrado en el desarrollo de materiales de base biológica con buen comportamiento frente al fuego y la investigación de los mecanismos de los retardantes de llama involucrados. La investigación se desarrolló en tres etapas que se detallan a continuación. 1) Partiendo del concepto de base biológica, se seleccionaron PA y THAM como materias primas para sintetizar un nuevo retardante de llama y la estructura química se confirmó mediante la caracterización del compuesto resultante. Posteriormente, este producto sintético PA-THAM se empleó como un retardante de llama eficiente para PLA mediante mezcla fundida. Este sistema binario mostró una mejora en la resistencia al fuego, que se logró mediante una combinación de los efectos de transferencia de calor, ligera dilución y acción barrera. Por ejemplo, con sólo un 3% en peso de carga de PA-THAM se logró un valor de LOI de 25,8% del compuesto de PLA y un nivel UL 94 V-0, así como una capacidad de autoextinción significativa. Además, la viscosidad fundida del biocompuesto también se redujo en relación a la del PLA puro debido a la lubricación ejercida por el PA-THAM. Por otro lado, la adición del retardante ocasionó pocos cambios en las propiedades mecánicas. 2) El retardante basado en PA-THAM y la fracción fina obtenida triturando la médula de maíz (OCC) se combinaron mediante modificación in situ y se usaron para preparar un biocompuesto basado en PLA. La médula de maíz fue modificada con éxito con el PA-THAM, la cual cosa se demostró por SEM / EDS, FTIR y TGA, el efecto de PA-THAM sobre la estabilidad térmica y el comportamiento al fuego del material compuesto a base de PLA también fueron investigados. La adición de 5 phr de PA-THAM permitió a este biocompuesto reforzado con fibras naturales (NPC) alcanzar una temperatura 50 °C más alta en el punto de degradación máximo comparado con la muestra de control sin aditivo. También se obtuvo una mejora en el comportamiento al fuego con un aumento del valor de LOI, una reducción del pico máximo del ritmo de liberación de calor (PHRR), y una mayor formación de residuo carbonizado. El mecanismo ignífugo predominante se centró en el efecto sinérgico del PA-THAM y la OCC que ocurrió en la fase condensada. Además, el mismo nivel de introducción de PA-THAM mejoró la afinidad interfacial entre PLA y OCC que también mantuvo buenas propiedades mecánicas. 3) Se prepararon muestras de un material de aislamiento térmico de base biológica a partir de médula de maíz, alginato y retardantes de llama de origen biológico. La adición del retardante de llama de base biológica logró mejorar significativamente el comportamiento al fuego, y el fenómeno de combustión sin llama (smouldering). En comparación con la muestra de referencia, el panel aislante con una carga de 8% en peso de una mezcla de PA-THAM y una sal de borato de sodio (DOT) aumentó la temperatura inicial a la que se produce la combustión sin llama en 70 ºC y, permitió reducir el valor de PHRR en un 25.5%. Además, la conductividad térmica apenas se vio afectada, mientras que la temperatura a la que se produce el valor máximo de degradación térmica aumentó notablemente. El análisis del mecanismo de acción de los retardantes reveló la existencia de un efecto sinérgico de ambos retardantes de llama, que promovió la formación de una capa de carbonización más estable en la etapa inicial

Bio-based materials for fire-retardant application in construction products: a review.

Bio-based materials are showing great potential to be widely used in construction industry, while reducing fire risk and improving fire resistance of these alternatives also become a major concern due to their inherent flammability. Initially, this review introduces three common bio-based construction materials, including biopolymer-based materials, wood-based materials, and crop-based materials, and their fire behaviors in flaming and smoldering combustion scenarios, accompanied with some typical flame-retardant mechanisms. Sequentially, the recent achievements in improving fire resistance are mainly exhibited in detail for each kind of bio-based materials. There are numerous reports for biopolymer-based flame-retardant materials with mature flame-retardant methodology. With regard to wood-based flame-retardant materials, different criteria and methodologies are needed to evaluate the flame-retardant properties. Meanwhile, in the case of crop-based insulation materials is essential to carefully consider the fire behavior, both in flaming and smoldering combustions, and not only focus on their thermal performance. In the final section, based on the requirements of fire safety and practicality for construction materials, bio-based alternatives with excellent good fire resistance and practical performance are summarized to be a promising way to meet future challenges.pre-print1791 K

Analysis of laboratory repeat critical values at a large tertiary teaching hospital in China.

CONTEXT: As a patient safety measure, laboratories are required to have a critical values policy by regulatory agencies. Unfortunately, little information is available on repeat critical values for the same analyte(s) on the same patient. OBJECTIVE: To investigate the occurrence and distribution of repeat critical values and the relationship between the frequency of such values and patient outcome to provide information for hospitals on improving reporting policies. METHODS: Eleven laboratory critical value lists, including chemistry and hematology analytes, were selected from a tertiary hospital in China in the year 2010. The distribution and interval time for each repeat critical value were calculated. Serum potassium and platelet count were used as examples to illustrate the relationship between the frequency of the repeat critical values and patient outcome. RESULTS: All test items on the critical value list were prone to the occurrence of repeat critical values. On average, each patient who experienced critical values had 2.10 occurrences. The median interval time for each repeat critical value varied, with most being longer than 8 hours. For those patients who had repeat critical values of serum potassium and platelet count, along with the increased frequency, the patients had a longer hospital stay and a generally worse outcome. CONCLUSIONS: Patient can have a number of repeat critical values and the frequency of these values is closely related to patient outcome. A careful evaluation is warranted if a laboratory chooses to adopt a policy of not reporting each repeat critical value