Pub Date : 2023-03-01DOI: 10.1177/02624893231171662
J. Werner, D. Drummer
An increased awareness of sustainability among the population leads, from an industrial point of view, to efforts to act more ecologically as well as to the aim for lower production costs and an increased efficiency. With this in mind, a new process has been developed for foaming without blowing agents in rotational molding. Process related air inclusions in the polymer melt are expanded to form the cell structure by means of vacuum application. In the presented study, the influence of different particle sizes as well as the arising potential of deploying microgranules in the otherwise powder-based process is investigated with regard to the resulting foam cells. The results confirm that particle size and form greatly influence the existence and size of air inclusions in the polymer melt. It could be proven that these differences, caused by the particle characteristics, propagate during the foaming process and lead to different cell morphologies in the resultant foam. Furthermore, it is indicated that qualitative predictions of the resulting cell dimensions can be made on the basis of bulk density measurements and the analysis of the sintering behaviour of the initial particles.
{"title":"Influence of particle geometry and size on the cell morphology of vacuum assisted rotationally molded foam","authors":"J. Werner, D. Drummer","doi":"10.1177/02624893231171662","DOIUrl":"https://doi.org/10.1177/02624893231171662","url":null,"abstract":"An increased awareness of sustainability among the population leads, from an industrial point of view, to efforts to act more ecologically as well as to the aim for lower production costs and an increased efficiency. With this in mind, a new process has been developed for foaming without blowing agents in rotational molding. Process related air inclusions in the polymer melt are expanded to form the cell structure by means of vacuum application. In the presented study, the influence of different particle sizes as well as the arising potential of deploying microgranules in the otherwise powder-based process is investigated with regard to the resulting foam cells. The results confirm that particle size and form greatly influence the existence and size of air inclusions in the polymer melt. It could be proven that these differences, caused by the particle characteristics, propagate during the foaming process and lead to different cell morphologies in the resultant foam. Furthermore, it is indicated that qualitative predictions of the resulting cell dimensions can be made on the basis of bulk density measurements and the analysis of the sintering behaviour of the initial particles.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"42 1","pages":"107 - 122"},"PeriodicalIF":1.6,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47754723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-23DOI: 10.1177/02624893231151363
S. Yetgin, H. Unal
In this study, cellular polypropylene based composite foams were prepared using an universal injection moulding machine. The chemical foaming agent was added to neat polypropylene (PP) polymer, talc filled polypropylene (PP-T) composite and talc filled polypropylene/ethylene-propylene-diene blend (PP-T-EPDM) composite materials at the ratio of 1% and 2% by weight. The influence of foaming agent content on the mechanical and cellular properties of both neat PP polymer and PP composites was investigated. The results showed that the tensile strength, tensile modulus, impact strength, hardness, cell diameter, foam density and viscosity values and skin layer thickness decreased while volume expansion ratio increased with the increment in chemical blowing agent content.
{"title":"A study of the cell morphology and mechanical properties of bumper material PP-T-EPDM composite foam","authors":"S. Yetgin, H. Unal","doi":"10.1177/02624893231151363","DOIUrl":"https://doi.org/10.1177/02624893231151363","url":null,"abstract":"In this study, cellular polypropylene based composite foams were prepared using an universal injection moulding machine. The chemical foaming agent was added to neat polypropylene (PP) polymer, talc filled polypropylene (PP-T) composite and talc filled polypropylene/ethylene-propylene-diene blend (PP-T-EPDM) composite materials at the ratio of 1% and 2% by weight. The influence of foaming agent content on the mechanical and cellular properties of both neat PP polymer and PP composites was investigated. The results showed that the tensile strength, tensile modulus, impact strength, hardness, cell diameter, foam density and viscosity values and skin layer thickness decreased while volume expansion ratio increased with the increment in chemical blowing agent content.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"42 1","pages":"73 - 87"},"PeriodicalIF":1.6,"publicationDate":"2023-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45198374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-22DOI: 10.1177/02624893231152383
U. Soykan, Ş. Kaya
In this current study, rigid polyurethane foams (RPUFs) composites were prepared using different percentage (3, 6, 9 and 12%) of the hemp fibers via one-shut one-step polymerization method. The influences of the hemp fiber addition on the RPUFs were investigated meticulously by means of Fourier-transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), thermal conductivity measurement and scanning electron microscopy (SEM) techniques by evaluating the alternations in the chemical structures of the component, thermal stability, apparent density, insulation performance and cellular topology of the produced samples. The structural analysis revealed that there existed the strong secondary chemical bonds between the functional groups belonging to the components and, depending on that, the improvement in the thermal stability of the foam samples was recorded accompanied by the formation of the better interfacial adhesion. Furthermore, thermal conductivity values of the hemp fiber-loaded RPUFs were observed to increase regularly with the increasing of the content level of the hemp fibers. This was explained by enhancement in the bulk phase conduction level depending of the apparent density rising, reduction in CO2 concentration inside cells as well as the formation of the distorted cellular structures. The obtained air permeability results displayed that the hemp fibers incorporated successfully with RPUF structure, which provides the occurrence of the novel micro barriers and pathways limiting the passage of the air throughout the matrix. The taken scanning electron microscopy images also indicated that the cellular morphology and dimensional stability of the produced foams affected negatively by the hemp fiber addition. At high contents, the wrinkled, non-uniform and irregular cellular structures were observed with ruptured and collapsed walls and struts.
{"title":"Role of hemp fiber addition on thermal stability, heat insulation, air permeability and cellular structural features of rigid polyurethane foam","authors":"U. Soykan, Ş. Kaya","doi":"10.1177/02624893231152383","DOIUrl":"https://doi.org/10.1177/02624893231152383","url":null,"abstract":"In this current study, rigid polyurethane foams (RPUFs) composites were prepared using different percentage (3, 6, 9 and 12%) of the hemp fibers via one-shut one-step polymerization method. The influences of the hemp fiber addition on the RPUFs were investigated meticulously by means of Fourier-transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), thermal conductivity measurement and scanning electron microscopy (SEM) techniques by evaluating the alternations in the chemical structures of the component, thermal stability, apparent density, insulation performance and cellular topology of the produced samples. The structural analysis revealed that there existed the strong secondary chemical bonds between the functional groups belonging to the components and, depending on that, the improvement in the thermal stability of the foam samples was recorded accompanied by the formation of the better interfacial adhesion. Furthermore, thermal conductivity values of the hemp fiber-loaded RPUFs were observed to increase regularly with the increasing of the content level of the hemp fibers. This was explained by enhancement in the bulk phase conduction level depending of the apparent density rising, reduction in CO2 concentration inside cells as well as the formation of the distorted cellular structures. The obtained air permeability results displayed that the hemp fibers incorporated successfully with RPUF structure, which provides the occurrence of the novel micro barriers and pathways limiting the passage of the air throughout the matrix. The taken scanning electron microscopy images also indicated that the cellular morphology and dimensional stability of the produced foams affected negatively by the hemp fiber addition. At high contents, the wrinkled, non-uniform and irregular cellular structures were observed with ruptured and collapsed walls and struts.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"42 1","pages":"88 - 104"},"PeriodicalIF":1.6,"publicationDate":"2023-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43602186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-06DOI: 10.1177/02624893231151364
Laura Neves de Alencar, Fábio Friol Guedes Paiva, F. Okimoto, G. Bacarin, Guilherme Dognani, L. O. Salmazo, R. J. dos Santos, F. Cabrera, A. Job
With the advances in the field of civil construction and the world population growth, the development of policies is necessary for the management and reuse of generated residue. Thus, the present work proposes the use of expanded natural rubber as a polymeric matrix incorporated with eucalyptus filler as a reinforcing filler for the production of composites. Thermal insulation capacity was determined by the transient plane source and acoustic method by impedance tube. NR/W40 foam showed enhanced the acoustic insulation capacity. The maximum absorption of NR/W40 was 0.83, at 3257 Hz, which is three times higher than natural rubber foam. Highly inhomogeneous cell structures were observed with large, interconnected pores, improving the acoustic performance. Sound absorption coefficient for natural rubber foam with 40% wood (0.83 ± 0.046) was similar to PU foam (0.97 ± 0.009) with 20 mm in thickness, a density of 47 kg/m3 and 98% open cell content it is a well-known acoustic absorbent in the building sector. The NR/W40 sample recorded the best acoustic performance among the NR foams analyzed in this work, maintaining good sound absorption above 1500 Hz, demonstrating a possibility of wood reuse as a filler in based-rubber foam for acustic insulation.
{"title":"Natural rubber/wood composite foam: Thermal insulation and acoustic isolation materials for construction","authors":"Laura Neves de Alencar, Fábio Friol Guedes Paiva, F. Okimoto, G. Bacarin, Guilherme Dognani, L. O. Salmazo, R. J. dos Santos, F. Cabrera, A. Job","doi":"10.1177/02624893231151364","DOIUrl":"https://doi.org/10.1177/02624893231151364","url":null,"abstract":"With the advances in the field of civil construction and the world population growth, the development of policies is necessary for the management and reuse of generated residue. Thus, the present work proposes the use of expanded natural rubber as a polymeric matrix incorporated with eucalyptus filler as a reinforcing filler for the production of composites. Thermal insulation capacity was determined by the transient plane source and acoustic method by impedance tube. NR/W40 foam showed enhanced the acoustic insulation capacity. The maximum absorption of NR/W40 was 0.83, at 3257 Hz, which is three times higher than natural rubber foam. Highly inhomogeneous cell structures were observed with large, interconnected pores, improving the acoustic performance. Sound absorption coefficient for natural rubber foam with 40% wood (0.83 ± 0.046) was similar to PU foam (0.97 ± 0.009) with 20 mm in thickness, a density of 47 kg/m3 and 98% open cell content it is a well-known acoustic absorbent in the building sector. The NR/W40 sample recorded the best acoustic performance among the NR foams analyzed in this work, maintaining good sound absorption above 1500 Hz, demonstrating a possibility of wood reuse as a filler in based-rubber foam for acustic insulation.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"42 1","pages":"55 - 72"},"PeriodicalIF":1.6,"publicationDate":"2023-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45703032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-30DOI: 10.1177/02624893221143507
Xuemei Tan, D. Rodrigue
This article reviews the main developments associated with density graded polymer composite foams. After a short introduction, a discussion is made on both density graded polymer-based composites and foams separately to better understand the challenges when both structures are combined together to produce composite foams. In all cases, the basic concepts, fabrication methods, main properties and general applications are presented. Opening for future works are also presented to conclude.
{"title":"Density graded polymer composite foams","authors":"Xuemei Tan, D. Rodrigue","doi":"10.1177/02624893221143507","DOIUrl":"https://doi.org/10.1177/02624893221143507","url":null,"abstract":"This article reviews the main developments associated with density graded polymer composite foams. After a short introduction, a discussion is made on both density graded polymer-based composites and foams separately to better understand the challenges when both structures are combined together to produce composite foams. In all cases, the basic concepts, fabrication methods, main properties and general applications are presented. Opening for future works are also presented to conclude.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"42 1","pages":"25 - 51"},"PeriodicalIF":1.6,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49512823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-27DOI: 10.1177/02624893221130154
Jiaxing Zhang Hui Chen, Z. Shan
Using methacrylic acid (MAA) and methyl methacrylate (MMA) as core monomers and polystyrene as the shell layer, polymer hollow microspheres (PHM) with good stability were prepared by using an alkali osmotic swelling method followed by spray drying. The average size of the PHM was approximately 875 nm. As a filling cross-linking agent, the PHM were added to a skin collagen material to disperse and fix, and a “polymer hollow microsphere composite collagen fiber” (PHCC) material was obtained. The results show that the PHM improve the mechanical strength, thermal stability and water resistance of the skin collagen material. The PHCC material has a low thermal conductivity (0.035 W/(K·m)) and excellent sound insulation performance and retains the soft and delicate touch of leather, which has application value in high-grade decorative materials and functional leather. This provides a new approach for developing flexible sound-absorbing thermal insulation materials.
{"title":"A sound-absorbing and heat-insulating collagen fiber composite material","authors":"Jiaxing Zhang Hui Chen, Z. Shan","doi":"10.1177/02624893221130154","DOIUrl":"https://doi.org/10.1177/02624893221130154","url":null,"abstract":"Using methacrylic acid (MAA) and methyl methacrylate (MMA) as core monomers and polystyrene as the shell layer, polymer hollow microspheres (PHM) with good stability were prepared by using an alkali osmotic swelling method followed by spray drying. The average size of the PHM was approximately 875 nm. As a filling cross-linking agent, the PHM were added to a skin collagen material to disperse and fix, and a “polymer hollow microsphere composite collagen fiber” (PHCC) material was obtained. The results show that the PHM improve the mechanical strength, thermal stability and water resistance of the skin collagen material. The PHCC material has a low thermal conductivity (0.035 W/(K·m)) and excellent sound insulation performance and retains the soft and delicate touch of leather, which has application value in high-grade decorative materials and functional leather. This provides a new approach for developing flexible sound-absorbing thermal insulation materials.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"42 1","pages":"3 - 24"},"PeriodicalIF":1.6,"publicationDate":"2022-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42747691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-29DOI: 10.1177/02624893221123391
Alok K Upadhyay, A. Ullas
Polymer syntactic foams are lightweight polymer composites that are prepared by introducing hollow microspheres in a resin. The main endeavour is to obtain a significant reduction in the weight of the composite along with energy absorption. The present investigation aims to prepare poly (dimethylsiloxane) (PDMS)-hollow glass microballoons (HGM) (40–60% v/v) syntactic foams. Not only did HGM reduce the density of the syntactic foams but also act as a reinforcing phase and increase the compressive properties of PDMS. A ∼25% reduction in density was obtained in syntactic foam when compared to the neat elastomer. Similarly, an improvement of ∼118% in compressive strength was attained at 40% loading of HGM in PDMS. Specific compressive strength and toughness values also registered improvements of the order of ∼191 and ∼240% respectively which highlight the potential of PDMS syntactic foams in varied applications. Graphical Abstract
{"title":"Compressive Properties of Poly (Dimethylsiloxane)–Hollow Glass Microballoons Syntactic Foams","authors":"Alok K Upadhyay, A. Ullas","doi":"10.1177/02624893221123391","DOIUrl":"https://doi.org/10.1177/02624893221123391","url":null,"abstract":"Polymer syntactic foams are lightweight polymer composites that are prepared by introducing hollow microspheres in a resin. The main endeavour is to obtain a significant reduction in the weight of the composite along with energy absorption. The present investigation aims to prepare poly (dimethylsiloxane) (PDMS)-hollow glass microballoons (HGM) (40–60% v/v) syntactic foams. Not only did HGM reduce the density of the syntactic foams but also act as a reinforcing phase and increase the compressive properties of PDMS. A ∼25% reduction in density was obtained in syntactic foam when compared to the neat elastomer. Similarly, an improvement of ∼118% in compressive strength was attained at 40% loading of HGM in PDMS. Specific compressive strength and toughness values also registered improvements of the order of ∼191 and ∼240% respectively which highlight the potential of PDMS syntactic foams in varied applications. Graphical Abstract","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"41 1","pages":"243 - 251"},"PeriodicalIF":1.6,"publicationDate":"2022-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43900007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-26DOI: 10.1177/02624893221120535
Qian Wu, Huijie Gu, Haiyan Cui, Shu Zhou
Porous hydrogel dressings show breathability and possibility to carry and release basic fibroblast growth factor (bFGF) to promote wound healing. However, the difficult replacement may lead to the secondary damage. Thus, there is an urgent need to develop a method platform to control the degradation rate of hydrogel, so as to realize the on-demand replacement. The present study fabricated a porous hydrogel from co-polymized N,N′-bis(acryloyl) cystamine (BAC), allyl polyethylene glycol 500 (APEG500) and acrylic acid (AA) with the presence of polycaprolactone (PCL). BAC contains disulfide bond, which crosslinked the hydrogel. The pore size of the porous hydrogel was 400–600 μm. Higher content of BAC indicated higher crosslinking density, which reduced swelling ratio of hydrogel, while promoted hydrogel storage modulus. At the same time, the presence of PCL reduced swelling ratio of hydrogel, while promoted hydrogel mechanical properties, endowing hydrogel with tough feature. Porous hydrogels that crosslinked by disulfide bonds immersed in glutathione solution were found to degrade spontaneously and quickly due to the response to glutathione. Both crosslinking density and PCL content affected the degradation rate. The porous hydrogel carrying bFGF was applied to wound, promoting angiogenesis, thus accelerating wound healing within 12 d. Due to the spontaneous and rapid degradation of optimized porous hydrogel on wound within 3 days, there was no operation of removing dressing during treatment, avoiding damage during dressing replacement.
{"title":"Porous synthetic hydrogel carrying basic fibroblast growth factor with controllable and rapid degradation rate to promote wound healing","authors":"Qian Wu, Huijie Gu, Haiyan Cui, Shu Zhou","doi":"10.1177/02624893221120535","DOIUrl":"https://doi.org/10.1177/02624893221120535","url":null,"abstract":"Porous hydrogel dressings show breathability and possibility to carry and release basic fibroblast growth factor (bFGF) to promote wound healing. However, the difficult replacement may lead to the secondary damage. Thus, there is an urgent need to develop a method platform to control the degradation rate of hydrogel, so as to realize the on-demand replacement. The present study fabricated a porous hydrogel from co-polymized N,N′-bis(acryloyl) cystamine (BAC), allyl polyethylene glycol 500 (APEG500) and acrylic acid (AA) with the presence of polycaprolactone (PCL). BAC contains disulfide bond, which crosslinked the hydrogel. The pore size of the porous hydrogel was 400–600 μm. Higher content of BAC indicated higher crosslinking density, which reduced swelling ratio of hydrogel, while promoted hydrogel storage modulus. At the same time, the presence of PCL reduced swelling ratio of hydrogel, while promoted hydrogel mechanical properties, endowing hydrogel with tough feature. Porous hydrogels that crosslinked by disulfide bonds immersed in glutathione solution were found to degrade spontaneously and quickly due to the response to glutathione. Both crosslinking density and PCL content affected the degradation rate. The porous hydrogel carrying bFGF was applied to wound, promoting angiogenesis, thus accelerating wound healing within 12 d. Due to the spontaneous and rapid degradation of optimized porous hydrogel on wound within 3 days, there was no operation of removing dressing during treatment, avoiding damage during dressing replacement.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"41 1","pages":"231 - 242"},"PeriodicalIF":1.6,"publicationDate":"2022-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49356022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to explore the potential utilization value of iron tailings, the typical solid waste-iron tailings was introduced into rigid polyurethane foam (RPUF) as a flame retardant filler in this paper. The flame retardant performance, combustion performance, gas-phase products and char residue’s related properties of RPUF/ITS composites were systematically investigated by limiting oxygen index, thermogravimetric (TG), cone calorimetry (CCT) and thermogravimetric-infrared spectrometry (TG-FTIR). The results showed that ITS improved the overall thermal stability of the composites, and the T-5%, T-50%, Tmax1, Tmax2 and char residue rates were all higher than those of the pure samples. The CCT indicated that ITS had a certain effect on smoke suppression and heat release reduction. The peak heat release rate of RPUF-6 was reduced by 22.75% compared with that of the pure sample, and the total smoke release of RPUF-2 was reduced by 25.36%. Smoke factor (SF), fire growth rate index and fire performance index indicated that ITS reduced the fire risk of RPUF/ITS composites. TG-FTIR showed that ITS inhibited the decomposition of RPUF/ITS composites, and the release intensity of hydrocarbons, CO2, isocyanate compound, CO, aromatic compounds and esters decreased significantly. TG, MCC, scanning electron microscope and Raman implied that ITS promoted the formation of a dense char layer in RPUF and improved the heat resistance of the char layer.
{"title":"Rigid polyurethane foam composites based on iron tailing: Thermal stability, flame retardancy and fire toxicity","authors":"Yadong Yang, Hai-jian Shen, Yuzhou Luo, Renhui Zhang, Junjie Sun, Xiuyu Liu, Zhifang Zong, Gang Tang","doi":"10.1177/02624893221105317","DOIUrl":"https://doi.org/10.1177/02624893221105317","url":null,"abstract":"In order to explore the potential utilization value of iron tailings, the typical solid waste-iron tailings was introduced into rigid polyurethane foam (RPUF) as a flame retardant filler in this paper. The flame retardant performance, combustion performance, gas-phase products and char residue’s related properties of RPUF/ITS composites were systematically investigated by limiting oxygen index, thermogravimetric (TG), cone calorimetry (CCT) and thermogravimetric-infrared spectrometry (TG-FTIR). The results showed that ITS improved the overall thermal stability of the composites, and the T-5%, T-50%, Tmax1, Tmax2 and char residue rates were all higher than those of the pure samples. The CCT indicated that ITS had a certain effect on smoke suppression and heat release reduction. The peak heat release rate of RPUF-6 was reduced by 22.75% compared with that of the pure sample, and the total smoke release of RPUF-2 was reduced by 25.36%. Smoke factor (SF), fire growth rate index and fire performance index indicated that ITS reduced the fire risk of RPUF/ITS composites. TG-FTIR showed that ITS inhibited the decomposition of RPUF/ITS composites, and the release intensity of hydrocarbons, CO2, isocyanate compound, CO, aromatic compounds and esters decreased significantly. TG, MCC, scanning electron microscope and Raman implied that ITS promoted the formation of a dense char layer in RPUF and improved the heat resistance of the char layer.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"41 1","pages":"189 - 207"},"PeriodicalIF":1.6,"publicationDate":"2022-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42672779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ying Jie Chee, Huiling Liew, Wai Han Hoi, Yingshan Lee, Brenda Lim, Han Xin Chin, Ray Tian Rui Lai, Yunqing Koh, Michelle Tham, Cherng Jye Seow, Zhi Han Quek, Abel Weiliang Chen, Timothy Peng Lim Quek, Alvin Wai Kit Tan, Rinkoo Dalan
Context and objective: Thyroid autoimmunity has been reported to be associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the SARS-CoV-2 vaccination recently. We report a series of patients who presented with new onset or relapse of Graves' disease-related hyperthyroidism shortly after receiving the SARS-CoV-2 messenger RNA (mRNA) vaccine at a single tertiary institution in Singapore.
Methods and results: We describe 12 patients who developed hyperthyroidism within a relatively short interval (median onset, 17 [range, 5-63] days) after receiving the SARS-CoV-2 mRNA vaccine. The majority were females (11/12) with median age of 35.5 (range, 22-74) years. Six patients had new-onset hyperthyroidism, whereas the other 6 had relapse of previously well-controlled Graves' disease. TSH receptor antibody concentrations ranged from 2.4 to 32 IU/L. The majority of the patients were able to go for the second dose of the vaccine without any further exacerbations. Literature review revealed 21 other similar cases reported from across the world.
Conclusion: Our case series provides insight into the characteristics of individuals in whom Graves' disease was triggered by the SARS-CoV-2 vaccination. Clinicians need to be vigilant of precipitation or exacerbation of autoimmune thyroid disorders in predisposed individuals after exposure to the SARS-CoV-2 vaccination. Further epidemiological and mechanistic studies are required to elucidate the possible associations between the SARS-CoV-2 vaccines and the development of thyroid autoimmunity.
{"title":"SARS-CoV-2 mRNA Vaccination and Graves' Disease: A Report of 12 Cases and Review of the Literature.","authors":"Ying Jie Chee, Huiling Liew, Wai Han Hoi, Yingshan Lee, Brenda Lim, Han Xin Chin, Ray Tian Rui Lai, Yunqing Koh, Michelle Tham, Cherng Jye Seow, Zhi Han Quek, Abel Weiliang Chen, Timothy Peng Lim Quek, Alvin Wai Kit Tan, Rinkoo Dalan","doi":"10.1210/clinem/dgac119","DOIUrl":"10.1210/clinem/dgac119","url":null,"abstract":"<p><strong>Context and objective: </strong>Thyroid autoimmunity has been reported to be associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the SARS-CoV-2 vaccination recently. We report a series of patients who presented with new onset or relapse of Graves' disease-related hyperthyroidism shortly after receiving the SARS-CoV-2 messenger RNA (mRNA) vaccine at a single tertiary institution in Singapore.</p><p><strong>Methods and results: </strong>We describe 12 patients who developed hyperthyroidism within a relatively short interval (median onset, 17 [range, 5-63] days) after receiving the SARS-CoV-2 mRNA vaccine. The majority were females (11/12) with median age of 35.5 (range, 22-74) years. Six patients had new-onset hyperthyroidism, whereas the other 6 had relapse of previously well-controlled Graves' disease. TSH receptor antibody concentrations ranged from 2.4 to 32 IU/L. The majority of the patients were able to go for the second dose of the vaccine without any further exacerbations. Literature review revealed 21 other similar cases reported from across the world.</p><p><strong>Conclusion: </strong>Our case series provides insight into the characteristics of individuals in whom Graves' disease was triggered by the SARS-CoV-2 vaccination. Clinicians need to be vigilant of precipitation or exacerbation of autoimmune thyroid disorders in predisposed individuals after exposure to the SARS-CoV-2 vaccination. Further epidemiological and mechanistic studies are required to elucidate the possible associations between the SARS-CoV-2 vaccines and the development of thyroid autoimmunity.</p>","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"36 1","pages":"e2324-e2330"},"PeriodicalIF":5.8,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8903505/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79880953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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