Pub Date : 2021-03-01DOI: 10.1177/0262489321988970
Serife Akkoyun, Meral Akkoyun
The aim of this work is the fabrication of electrically insulating composite rigid polyurethane foams with improved thermal conductivity. Therefore, this study is focused on the effect of aluminum nitride (AlN) on the thermal and electrical conductivities of rigid polyurethane foams. For this purpose, aluminum nitride/rigid polyurethane composite foams were prepared using a three-step procedure. The electrical and thermal conductivities of the foams were characterized. The thermal transitions, mechanical properties and morphology of the foams were also examined. The results reveal that AlN induces an increase of the thermal conductivity of rigid polyurethane foam of 24% which seems to be a relatively noticeable increase in polymeric foams. The low electrical conductivity of the foams is preserved.
{"title":"Improvement of thermal conductivity of rigid polyurethane foams with aluminum nitride filler","authors":"Serife Akkoyun, Meral Akkoyun","doi":"10.1177/0262489321988970","DOIUrl":"https://doi.org/10.1177/0262489321988970","url":null,"abstract":"The aim of this work is the fabrication of electrically insulating composite rigid polyurethane foams with improved thermal conductivity. Therefore, this study is focused on the effect of aluminum nitride (AlN) on the thermal and electrical conductivities of rigid polyurethane foams. For this purpose, aluminum nitride/rigid polyurethane composite foams were prepared using a three-step procedure. The electrical and thermal conductivities of the foams were characterized. The thermal transitions, mechanical properties and morphology of the foams were also examined. The results reveal that AlN induces an increase of the thermal conductivity of rigid polyurethane foam of 24% which seems to be a relatively noticeable increase in polymeric foams. The low electrical conductivity of the foams is preserved.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"40 1","pages":"87 - 98"},"PeriodicalIF":1.6,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489321988970","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41726370","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 : 2020-11-25DOI: 10.1177/0262489320971796
M. Tumedei, A. Piattelli, A. Falco, F. de Angelis, F. Lorusso, M. Di Carmine, G. Iezzi
The dental implant primary stability and micromovement absence represent critical factor for dental implant osseointegration. The aim of the present in vitro investigation was to simulate the bone response on different polyurethane densities the effect of self-tapping threads and round apex implant geometry. A total of 40 implants were positioned in D1, D2, D3 and D4 polyurethane block densities following a calibrated drilling protocol. The Insertion, removal Torque and resonance frequency analysis (RFA) means were calculated. All experimental conditions showed insertion torque values >30 Ncm. A significant higher insertion torque, removal and RFA was present in D1 polyurethane. Similar evidences were evidenced for D3 and D4. The effectiveness of the present study suggested a valuable clinical advantage for self-tapping threads and round apex implant using, such as in case of reduced bone density in the posterior maxilla
{"title":"An in vitro evaluation on polyurethane foam sheets of the insertion torque, removal torque values, and resonance frequency analysis (RFA) of a self-tapping threads and round apex implant","authors":"M. Tumedei, A. Piattelli, A. Falco, F. de Angelis, F. Lorusso, M. Di Carmine, G. Iezzi","doi":"10.1177/0262489320971796","DOIUrl":"https://doi.org/10.1177/0262489320971796","url":null,"abstract":"The dental implant primary stability and micromovement absence represent critical factor for dental implant osseointegration. The aim of the present in vitro investigation was to simulate the bone response on different polyurethane densities the effect of self-tapping threads and round apex implant geometry. A total of 40 implants were positioned in D1, D2, D3 and D4 polyurethane block densities following a calibrated drilling protocol. The Insertion, removal Torque and resonance frequency analysis (RFA) means were calculated. All experimental conditions showed insertion torque values >30 Ncm. A significant higher insertion torque, removal and RFA was present in D1 polyurethane. Similar evidences were evidenced for D3 and D4. The effectiveness of the present study suggested a valuable clinical advantage for self-tapping threads and round apex implant using, such as in case of reduced bone density in the posterior maxilla","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"40 1","pages":"20 - 30"},"PeriodicalIF":1.6,"publicationDate":"2020-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489320971796","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49492795","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 : 2020-08-04DOI: 10.1177/0262489320929226
Miriam Trigo-lopez, José A. Reglero Ruiz, Saúl Vallejos, C. Ramos, S. Beltrán, F. García, J. García
We report on the preparation, characterization, and foaming behavior of cellular polymers based on 1-vinyl-2-pyrrolidone (VP) and methyl methacrylate (MMA). Samples with different feed ratios proportions of VP and MMA were prepared following the bulk radical copolymerization procedure, using commercially available monomers and testing two different initiators (photochemical and thermal), obtaining solid samples of around 1.5 mm thick. To evaluate the polymerization process, the chemical structure of VP/MMA copolymers was determined by proton nuclear magnetic resonance measurements. In a second step, single-batch supercritical carbon dioxide (CO2) foaming tests were carried out at different temperatures to evaluate the influence of the VP to MMA feed ratios and the foaming temperature in the density, the presence of solid outer skin, the CO2 sorption–desorption process, and the cellular morphology of the foamed polymers.
{"title":"Foaming behavior of 1-vinyl-2-pyrrolidone–methyl methacrylate copolymers under ScCO2","authors":"Miriam Trigo-lopez, José A. Reglero Ruiz, Saúl Vallejos, C. Ramos, S. Beltrán, F. García, J. García","doi":"10.1177/0262489320929226","DOIUrl":"https://doi.org/10.1177/0262489320929226","url":null,"abstract":"We report on the preparation, characterization, and foaming behavior of cellular polymers based on 1-vinyl-2-pyrrolidone (VP) and methyl methacrylate (MMA). Samples with different feed ratios proportions of VP and MMA were prepared following the bulk radical copolymerization procedure, using commercially available monomers and testing two different initiators (photochemical and thermal), obtaining solid samples of around 1.5 mm thick. To evaluate the polymerization process, the chemical structure of VP/MMA copolymers was determined by proton nuclear magnetic resonance measurements. In a second step, single-batch supercritical carbon dioxide (CO2) foaming tests were carried out at different temperatures to evaluate the influence of the VP to MMA feed ratios and the foaming temperature in the density, the presence of solid outer skin, the CO2 sorption–desorption process, and the cellular morphology of the foamed polymers.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"39 1","pages":"203 - 219"},"PeriodicalIF":1.6,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489320929226","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43158645","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 : 2020-07-01DOI: 10.1177/0262489319897633
Rupesh Dugad, G. Radhakrishna, A. Gandhi
In this work, microcellular acrylonitrile-butadiene-styrene foams were developed with utilization of water as a co-blowing agent and CO2 as the primary blowing agent through the solid-state batch foaming process. The effect of saturation parameters with the content of the co-blowing agent has been studied extensively for various foaming attributes. The co-blowing agent enhanced the average cell size and the expansion ratio which are useful for better thermal insulation. The maximum expansion ratio of 29.9 obtained from the effect of saturation temperature and co-blowing agent, 23.6 from the effect of saturation pressure and co-blowing agent, and 22.4 from the effect of saturation time and co-blowing agent. The co-blowing agent significantly affects the cell morphology of polymeric foam with saturation parameters.
{"title":"Morphological evaluation of ultralow density microcellular foamed composites developed through CO2-induced solid-state batch foaming technique utilizing water as co-blowing agent","authors":"Rupesh Dugad, G. Radhakrishna, A. Gandhi","doi":"10.1177/0262489319897633","DOIUrl":"https://doi.org/10.1177/0262489319897633","url":null,"abstract":"In this work, microcellular acrylonitrile-butadiene-styrene foams were developed with utilization of water as a co-blowing agent and CO2 as the primary blowing agent through the solid-state batch foaming process. The effect of saturation parameters with the content of the co-blowing agent has been studied extensively for various foaming attributes. The co-blowing agent enhanced the average cell size and the expansion ratio which are useful for better thermal insulation. The maximum expansion ratio of 29.9 obtained from the effect of saturation temperature and co-blowing agent, 23.6 from the effect of saturation pressure and co-blowing agent, and 22.4 from the effect of saturation time and co-blowing agent. The co-blowing agent significantly affects the cell morphology of polymeric foam with saturation parameters.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"39 1","pages":"141 - 171"},"PeriodicalIF":1.6,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489319897633","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41508038","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 : 2020-07-01DOI: 10.1177/0262489320934258
O. Kazantsev, K. V. Shirshin, P. V. Kornienko, A. P. Sivokhin
The review summarises the trends in the development of research on the synthesis of polymethacrylimides (PMIs) and polyacrylimides by the method of intramolecular thermal imidisation of (meth)acrylic polymers. Along with the widely used industry variant of PMI foam of the ‘Rohacell’ series based on bulk copolymers of methacrylonitrile and methacrylic acid, intensive research on alternative variants began after 2005. This review describes the main and side reactions when using polymer precursors of different structures as well as the effect of precursor composition and structure on the properties of the resulting poly(meth)acrylimides. It has been shown that the achievements of the last 15 years provide a basis for reducing the cost of poly(meth)acrylimides which will significantly expand the areas and scale of their application.
{"title":"Achievements and prospects for the synthesis of poly(meth)acrylimide foams. Stage of the thermal imidisation of polymer precursors","authors":"O. Kazantsev, K. V. Shirshin, P. V. Kornienko, A. P. Sivokhin","doi":"10.1177/0262489320934258","DOIUrl":"https://doi.org/10.1177/0262489320934258","url":null,"abstract":"The review summarises the trends in the development of research on the synthesis of polymethacrylimides (PMIs) and polyacrylimides by the method of intramolecular thermal imidisation of (meth)acrylic polymers. Along with the widely used industry variant of PMI foam of the ‘Rohacell’ series based on bulk copolymers of methacrylonitrile and methacrylic acid, intensive research on alternative variants began after 2005. This review describes the main and side reactions when using polymer precursors of different structures as well as the effect of precursor composition and structure on the properties of the resulting poly(meth)acrylimides. It has been shown that the achievements of the last 15 years provide a basis for reducing the cost of poly(meth)acrylimides which will significantly expand the areas and scale of their application.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"40 1","pages":"31 - 52"},"PeriodicalIF":1.6,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489320934258","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45435762","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 : 2020-06-26DOI: 10.1177/0262489320934263
A. Simpson, Ig Rattigan, E. Kalavsky, G. Parr
This article focuses on the thermal conductivity of 50 mm thick silver grey (infrared absorbing) expanded polystyrene (EPS) foam boards blown with pentane. The effect of short-term ageing from the point of production, by ambient conditioning at 23°C/50% RH, is compared to conditioning at an elevated temperature of 70°C. The declared thermal properties of the product and CE certification are fulfilled by the requirements of the European EPS product standard and SG19 Guidance. Measured thermal conductivity levels within 1% of the final value are acceptable and considered representative throughout the economic life of the product. Levels within the criteria were determined for 50 mm silver EPS after conditioning for 5 days at an elevated temperature of 70°C, whereas for conditioning at 23°C/50% RH the time taken was 23 days. The latter time is in good accord with retesting retained grey EPS boards of similar density and up to 9 years old, after initial testing 22 days from production, and conditioning at 23°C/50% RH. Elevated temperature conditioning increases the rate of diffusion of the blowing agent, but there has been concern about EPS beads softening above 60°C. Although there is little evidence from scanning electron microscopy of significant increase in perforation of the cell membranes at elevated temperatures, there is some indication of a small increase in wrinkling of the walls and intercell skeletal strands at 60°C and 70°C. It takes longer to eliminate the pentane gas by conditioning at 23°C/50% RH but there is no risk of material change from heat conditioning.
{"title":"Thermal conductivity and conditioning of grey expanded polystyrene foams","authors":"A. Simpson, Ig Rattigan, E. Kalavsky, G. Parr","doi":"10.1177/0262489320934263","DOIUrl":"https://doi.org/10.1177/0262489320934263","url":null,"abstract":"This article focuses on the thermal conductivity of 50 mm thick silver grey (infrared absorbing) expanded polystyrene (EPS) foam boards blown with pentane. The effect of short-term ageing from the point of production, by ambient conditioning at 23°C/50% RH, is compared to conditioning at an elevated temperature of 70°C. The declared thermal properties of the product and CE certification are fulfilled by the requirements of the European EPS product standard and SG19 Guidance. Measured thermal conductivity levels within 1% of the final value are acceptable and considered representative throughout the economic life of the product. Levels within the criteria were determined for 50 mm silver EPS after conditioning for 5 days at an elevated temperature of 70°C, whereas for conditioning at 23°C/50% RH the time taken was 23 days. The latter time is in good accord with retesting retained grey EPS boards of similar density and up to 9 years old, after initial testing 22 days from production, and conditioning at 23°C/50% RH. Elevated temperature conditioning increases the rate of diffusion of the blowing agent, but there has been concern about EPS beads softening above 60°C. Although there is little evidence from scanning electron microscopy of significant increase in perforation of the cell membranes at elevated temperatures, there is some indication of a small increase in wrinkling of the walls and intercell skeletal strands at 60°C and 70°C. It takes longer to eliminate the pentane gas by conditioning at 23°C/50% RH but there is no risk of material change from heat conditioning.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"39 1","pages":"238 - 262"},"PeriodicalIF":1.6,"publicationDate":"2020-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489320934263","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46025099","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 : 2020-06-10DOI: 10.1177/0262489320929300
Z. Razzaz, A. Mohebbi, D. Rodrigue
The production of foamed hollow fiber membranes (HFMs) is presented based on polymer blends using various concentrations of linear low-density polyethylene (LLDPE) and low-density polyethylene (LPDE) combined with azodicarbonamide (chemical blowing agent) to prepare samples via twin-screw extrusion. In particular, the blowing agent concentration as well as the stretching speed were found to be the most important parameters to achieve a good cellular structure for membrane application. From the samples obtained, a complete set of morphological, thermal, and gas transport characterization was performed. The results show that LLDPE/LDPE blends compared to neat LLDPE lead to higher cell density at high stretching speed, which is appropriate for membranes having higher gas permeability and selectivity due to lower cell wall thickness. The results also show that the developed cellular structure has high potential for the continuous production of HFMs for different gas separation, especially for hydrogen recovery.
{"title":"Gas transport properties of cellular hollow fiber membranes based on LLDPE/LDPE blends","authors":"Z. Razzaz, A. Mohebbi, D. Rodrigue","doi":"10.1177/0262489320929300","DOIUrl":"https://doi.org/10.1177/0262489320929300","url":null,"abstract":"The production of foamed hollow fiber membranes (HFMs) is presented based on polymer blends using various concentrations of linear low-density polyethylene (LLDPE) and low-density polyethylene (LPDE) combined with azodicarbonamide (chemical blowing agent) to prepare samples via twin-screw extrusion. In particular, the blowing agent concentration as well as the stretching speed were found to be the most important parameters to achieve a good cellular structure for membrane application. From the samples obtained, a complete set of morphological, thermal, and gas transport characterization was performed. The results show that LLDPE/LDPE blends compared to neat LLDPE lead to higher cell density at high stretching speed, which is appropriate for membranes having higher gas permeability and selectivity due to lower cell wall thickness. The results also show that the developed cellular structure has high potential for the continuous production of HFMs for different gas separation, especially for hydrogen recovery.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"40 1","pages":"119 - 140"},"PeriodicalIF":1.6,"publicationDate":"2020-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489320929300","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43631947","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 : 2020-06-05DOI: 10.1177/0262489320930328
Jinwei Chen, Ling Yang, Dahua Chen, Qunshan Mai, Meigui Wang, Lixuan Wu, Ping Kong
Microcellular polylactic acid (PLA) foams with various cell size and cell morphologies were prepared using supercritical carbon dioxide (sc-CO2) solid-state foaming to investigate the relationship between the cell structure and mechanical properties. Constrained foaming was used and a wide range of cell structures with a constant porosity of ∼75% by tuning saturation pressure (8–24 MPa) was developed. Experiments varying the saturation pressure while holding other variables’ constant show that the mean cell size and the mean cell wall thickness decreased, while the cell density and the open porosity increased with increase of pressure. Tensile modulus of PLA foams decreased with increasing the saturation pressure, but the specific tensile modulus of PLA foams was still 15–80% higher than that of solid PLA. Tensile strength and elongation at break first increased with increasing saturation pressure up to 16 MPa and then decreased with further increasing saturation pressure (20 MPa and 24 MPa) at which opened-cell structure produced. Compressive modulus, compressive strength, and compressive yield stress also followed the same variation trend. The results indicated that not only cell size plays an important role in properties of PLA foams but also cell morphology can influence these properties significantly.
{"title":"Cell structure and mechanical properties of microcellular PLA foams prepared via autoclave constrained foaming","authors":"Jinwei Chen, Ling Yang, Dahua Chen, Qunshan Mai, Meigui Wang, Lixuan Wu, Ping Kong","doi":"10.1177/0262489320930328","DOIUrl":"https://doi.org/10.1177/0262489320930328","url":null,"abstract":"Microcellular polylactic acid (PLA) foams with various cell size and cell morphologies were prepared using supercritical carbon dioxide (sc-CO2) solid-state foaming to investigate the relationship between the cell structure and mechanical properties. Constrained foaming was used and a wide range of cell structures with a constant porosity of ∼75% by tuning saturation pressure (8–24 MPa) was developed. Experiments varying the saturation pressure while holding other variables’ constant show that the mean cell size and the mean cell wall thickness decreased, while the cell density and the open porosity increased with increase of pressure. Tensile modulus of PLA foams decreased with increasing the saturation pressure, but the specific tensile modulus of PLA foams was still 15–80% higher than that of solid PLA. Tensile strength and elongation at break first increased with increasing saturation pressure up to 16 MPa and then decreased with further increasing saturation pressure (20 MPa and 24 MPa) at which opened-cell structure produced. Compressive modulus, compressive strength, and compressive yield stress also followed the same variation trend. The results indicated that not only cell size plays an important role in properties of PLA foams but also cell morphology can influence these properties significantly.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"40 1","pages":"101 - 118"},"PeriodicalIF":1.6,"publicationDate":"2020-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489320930328","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49474206","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 : 2020-06-04DOI: 10.1177/0262489320929232
Chunhui Li, Haihong Ma, Zhengfa Zhou, Weibing Xu, F. Ren, Xinyu Yang
Toughing melamine-formaldehyde (MF) rigid closed-cell foams were prepared by using ethylene glycol (EG) and carbon fiber (CF) as composite toughening agents. The pulverization rate, compressive strength, bending strength, cellular structure, closed-cell ratio, water absorption ratio, thermal conductivity, thermal stability, limiting oxygen index (LOI), and char yield were characterized to study the morphology, mechanical, thermal, and fire-retardant properties of as-prepared toughing MF rigid foams. The pulverization rate result showed that introduction of composite modifier can obviously improve the toughness of MF rigid foams. The cellular structure, closed-cell ratio, and water absorption results showed that the addition of EG/CF can increase the closed-cell ratio and control the cell size of MF rigid foams. The compressive strength and bending strength results showed that the incorporation of composite modifier of MF rigid foams dramatically improved the mechanical properties. The LOI, char yield, and thermal stability results showed that the toughing MF rigid foams remained more intact char skeleton with flame-retardant effect, thus reducing the fire hazards. The as-prepared toughing MF rigid foams showed the best comprehensive performance with pulverization rate of 5.21%, compressive strength of 355.3 kPa, bending strength of 0.44 MPa, closed-cell ratio of 79.1%, water absorption of 9%, thermal conductivity of 0.031 W m−1 K−1, and LOI of 39.6%. Compared with unmodified MF rigid foams, toughing rigid closed-cell MF foams possess excellent pulverization rate, compressive strength, bending strength, cellular structure, thermal insulation, and flame retardancy.
以乙二醇(EG)和碳纤维(CF)为复合增韧剂，制备了三聚氰胺-甲醛(MF)刚性闭孔泡沫塑料。通过表征制粒率、抗压强度、抗弯强度、孔结构、闭孔比、吸水率、导热系数、热稳定性、极限氧指数(LOI)和炭产率，研究了制备的增韧MF刚性泡沫的形貌、力学性能、热性能和阻燃性能。粉碎率试验结果表明，复合改性剂的加入能明显提高MF刚性泡沫的韧性。细胞结构、闭孔率和吸水率结果表明，EG/CF的加入可以提高MF刚性泡沫的闭孔率，控制孔的大小。抗压强度和弯曲强度结果表明，复合改性剂的掺入显著改善了MF刚性泡沫的力学性能。LOI、炭产率和热稳定性结果表明，增韧MF刚性泡沫保持了更完整的炭骨架，具有阻燃作用，从而降低了火灾危险。制备的增韧MF刚性泡沫粉化率为5.21%，抗压强度为355.3 kPa，抗弯强度为0.44 MPa，闭孔率为79.1%，吸水率为9%，导热系数为0.031 W m−1 K−1,LOI为39.6%，综合性能最佳。与未改性的MF刚性泡沫相比，增韧MF闭孔刚性泡沫具有优异的粉碎率、抗压强度、抗弯强度、孔状结构、保温性能和阻燃性能。
{"title":"Preparation and properties of melamine-formaldehyde rigid closed-cell foam toughened by ethylene glycol/carbon fiber","authors":"Chunhui Li, Haihong Ma, Zhengfa Zhou, Weibing Xu, F. Ren, Xinyu Yang","doi":"10.1177/0262489320929232","DOIUrl":"https://doi.org/10.1177/0262489320929232","url":null,"abstract":"Toughing melamine-formaldehyde (MF) rigid closed-cell foams were prepared by using ethylene glycol (EG) and carbon fiber (CF) as composite toughening agents. The pulverization rate, compressive strength, bending strength, cellular structure, closed-cell ratio, water absorption ratio, thermal conductivity, thermal stability, limiting oxygen index (LOI), and char yield were characterized to study the morphology, mechanical, thermal, and fire-retardant properties of as-prepared toughing MF rigid foams. The pulverization rate result showed that introduction of composite modifier can obviously improve the toughness of MF rigid foams. The cellular structure, closed-cell ratio, and water absorption results showed that the addition of EG/CF can increase the closed-cell ratio and control the cell size of MF rigid foams. The compressive strength and bending strength results showed that the incorporation of composite modifier of MF rigid foams dramatically improved the mechanical properties. The LOI, char yield, and thermal stability results showed that the toughing MF rigid foams remained more intact char skeleton with flame-retardant effect, thus reducing the fire hazards. The as-prepared toughing MF rigid foams showed the best comprehensive performance with pulverization rate of 5.21%, compressive strength of 355.3 kPa, bending strength of 0.44 MPa, closed-cell ratio of 79.1%, water absorption of 9%, thermal conductivity of 0.031 W m−1 K−1, and LOI of 39.6%. Compared with unmodified MF rigid foams, toughing rigid closed-cell MF foams possess excellent pulverization rate, compressive strength, bending strength, cellular structure, thermal insulation, and flame retardancy.","PeriodicalId":9816,"journal":{"name":"Cellular Polymers","volume":"40 1","pages":"55 - 72"},"PeriodicalIF":1.6,"publicationDate":"2020-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1177/0262489320929232","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44801488","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 : 2020-05-01DOI: 10.1177/0262489319890076
Tianzheng Wen, Fei Guo, Yijie Huang, S. Zhu, X. Jia
We established a method for calculating and analyzing the static leakage rate based on a porous media model for foamed silicone rubber materials. The mechanical properties of the foamed silicone rubber material under macroscopic compression were described by the Ogden third (foam) model in the finite-element hyperelastic model. It solved the problem of difficult convergence of large compressible and volume compressible cell materials. The size and distribution of the cells on the surface of the foamed material were obtained by a white-light interferometer and mathematical fitting. The boundary conditions for solving the porous medium model were obtained by the coupling of the macroscopic contact pressure and the microscopic cell contact pressure. For the unique cell structure and contact state of the surface of the foamed material, the flow state of the fluid at the sealing interface was described by a porous medium model, and the leak rate was obtained. In addition, this article analyzed the effect of different compression and the relative pressure of the sealing end face on the leakage.
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