Pub Date : 2022-12-24DOI: 10.1177/0021955X221147830
Aliakbar Nazari, M. Khanzadeh-Moradllo
Simulation of the microstructure of materials is not usually an efficient approach to estimate the mechanical response in the macro-scale porous components. This paper establishes an adaptive numerical model which reflects the effective mechanical properties of the elastomeric foam materials in the macro-scale, based on the material response in local points. The proposed adaptive model is capable of characterizing the dominant state of stress at each section point and assigning the corresponding mechanical properties from a developed material library. This material library can propose different stress-strain responses of the foam material based on mechanical characterization experiments and using the best-fit energy functions. The material of study is an elastomeric foam with a blend of Polyethylene/Ethylene-vinyl acetate (PE-EVA). The efficiency and performance of the adaptive model were examined using two practical case studies, in which the material was exposed to multiaxial stress conditions (a foam beam and a composite sandwich beam with a foam core under a concentrated loading). The adaptive model accurately predicts the dominant response of the foam beam and composite sandwich beam under flexural loading conditions. However, the uniaxial hyperelastic material models, calibrated by the pure tensile or compressive response of the foam material, dramatically overestimate or underestimate the experimental results.
{"title":"Developing an adaptive FE model to reflect the effective mechanical properties in porous elastomeric materials","authors":"Aliakbar Nazari, M. Khanzadeh-Moradllo","doi":"10.1177/0021955X221147830","DOIUrl":"https://doi.org/10.1177/0021955X221147830","url":null,"abstract":"Simulation of the microstructure of materials is not usually an efficient approach to estimate the mechanical response in the macro-scale porous components. This paper establishes an adaptive numerical model which reflects the effective mechanical properties of the elastomeric foam materials in the macro-scale, based on the material response in local points. The proposed adaptive model is capable of characterizing the dominant state of stress at each section point and assigning the corresponding mechanical properties from a developed material library. This material library can propose different stress-strain responses of the foam material based on mechanical characterization experiments and using the best-fit energy functions. The material of study is an elastomeric foam with a blend of Polyethylene/Ethylene-vinyl acetate (PE-EVA). The efficiency and performance of the adaptive model were examined using two practical case studies, in which the material was exposed to multiaxial stress conditions (a foam beam and a composite sandwich beam with a foam core under a concentrated loading). The adaptive model accurately predicts the dominant response of the foam beam and composite sandwich beam under flexural loading conditions. However, the uniaxial hyperelastic material models, calibrated by the pure tensile or compressive response of the foam material, dramatically overestimate or underestimate the experimental results.","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"27 1","pages":"3 - 27"},"PeriodicalIF":2.5,"publicationDate":"2022-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83306489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-01DOI: 10.1177/0021955X221144564
Abdulwasiu Muhammed Raji, H. Hambali, Z. I. Khan, Zurina Binti Mohamad, Hassan Azman, R. Ogabi
Owing to the superior thermal insulating attributes of rigid polyurethane foam (RPUF) compared to other insulating materials (expanded and extruded polystyrene, mineral wool), it remains the most dominant insulating material and most studied polymer foam. Like other polyurethane foam, RPUF is highly flammable, necessitating the incorporation of flame retardants (FR) during production to lower combustibility, promoting its continuous use as insulation material in construction, transportation, and others. The popular approaches for correcting the high flammability of RPUF are copolymerization and blending (with FR). The second method has proven to be most effective as there are limited trade-offs in RPUF properties. Meanwhile, the high flammability of RPUF is still a significant hindrance in emerging applications (sensors, space travel, and others), and this has continuously inspired research in the flame retardancy of RPUF. In this study, properties, and preparation methods of RPUF are described, factors responsible for the high flammability of PUF are discussed, and flame retardancy of RPUF is thoroughly reviewed. Notably, most FR for RPUF are inorganic nanoparticles, lignin, intumescent FR systems of expandable graphite (EG), ammonium polyphosphate (APP), and hybridized APP or EG with other FR. These could be due to their ease of processing, low cost, and being environmentally benign. Elaborate discussion on RPUF FR mechanisms were also highlighted. Lastly, a summary and future perspectives in fireproofing RPUF are provided, which could inspire the design of new FR for RPUF. Graphical Abstract
{"title":"Emerging trends in flame retardancy of rigid polyurethane foam and its composites: A review","authors":"Abdulwasiu Muhammed Raji, H. Hambali, Z. I. Khan, Zurina Binti Mohamad, Hassan Azman, R. Ogabi","doi":"10.1177/0021955X221144564","DOIUrl":"https://doi.org/10.1177/0021955X221144564","url":null,"abstract":"Owing to the superior thermal insulating attributes of rigid polyurethane foam (RPUF) compared to other insulating materials (expanded and extruded polystyrene, mineral wool), it remains the most dominant insulating material and most studied polymer foam. Like other polyurethane foam, RPUF is highly flammable, necessitating the incorporation of flame retardants (FR) during production to lower combustibility, promoting its continuous use as insulation material in construction, transportation, and others. The popular approaches for correcting the high flammability of RPUF are copolymerization and blending (with FR). The second method has proven to be most effective as there are limited trade-offs in RPUF properties. Meanwhile, the high flammability of RPUF is still a significant hindrance in emerging applications (sensors, space travel, and others), and this has continuously inspired research in the flame retardancy of RPUF. In this study, properties, and preparation methods of RPUF are described, factors responsible for the high flammability of PUF are discussed, and flame retardancy of RPUF is thoroughly reviewed. Notably, most FR for RPUF are inorganic nanoparticles, lignin, intumescent FR systems of expandable graphite (EG), ammonium polyphosphate (APP), and hybridized APP or EG with other FR. These could be due to their ease of processing, low cost, and being environmentally benign. Elaborate discussion on RPUF FR mechanisms were also highlighted. Lastly, a summary and future perspectives in fireproofing RPUF are provided, which could inspire the design of new FR for RPUF. Graphical Abstract","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"130 1","pages":"65 - 122"},"PeriodicalIF":2.5,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76227056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-01DOI: 10.1177/0021955X221141544
V. V. Zharkov, R. Vlasov
The method for determining the concentrations of the main functional groups in rigid polyisocyanurate (PIR) foams was developed using ATR-FTIR spectroscopy. On the example of a series of rigid PIR foams of isocyanate indexes (II) from 150 to 400, the contents of isocyanate, allophanate and isocyanurate groups was determined. It has been shown that a significant amount of isocyanate groups is accumulated in PIR foams in the form of allophanate, without passing into the target product – isocyanurate; the bulk of the urethane groups is converted to allophanate at high isocyanate indexes. With an increase in the isocyanate index, the conversion degree of isocyanate to isocyanurate decreases and when a certain isocyanate index is attained, reaches the limiting value.
{"title":"A quantitative study of the allophanate formation reaction in PIR foams by FT-IR spectroscopy","authors":"V. V. Zharkov, R. Vlasov","doi":"10.1177/0021955X221141544","DOIUrl":"https://doi.org/10.1177/0021955X221141544","url":null,"abstract":"The method for determining the concentrations of the main functional groups in rigid polyisocyanurate (PIR) foams was developed using ATR-FTIR spectroscopy. On the example of a series of rigid PIR foams of isocyanate indexes (II) from 150 to 400, the contents of isocyanate, allophanate and isocyanurate groups was determined. It has been shown that a significant amount of isocyanate groups is accumulated in PIR foams in the form of allophanate, without passing into the target product – isocyanurate; the bulk of the urethane groups is converted to allophanate at high isocyanate indexes. With an increase in the isocyanate index, the conversion degree of isocyanate to isocyanurate decreases and when a certain isocyanate index is attained, reaches the limiting value.","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"24 1","pages":"877 - 891"},"PeriodicalIF":2.5,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81705230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-01DOI: 10.1177/0021955X221144541
U. Soykan, Mustafa Khaleel, S. Çetin, U. Yahsi, C. Tav
Rigid polyurethane foams (RPUFs) were modified with 0–15 wt.% turkey feather fibers (TFFs) produced from waste turkey feathers. One-shut free rising method was used for the production of TFFs-filled-RPUFs in a closed mold. The dependence of mechanical performance and water vapor permeability (WVP) feature of the final foams on TFFs loading was evaluated with free volume change. The free volume analysis was performed via Positron Annihilation Lifetime Spectroscopy (PALS), while the mechanical and WVP characteristics were determined with the use of the universal tester machines. PALS findings showed that the incorporation of TFFs with RPUF matrix caused the considerable diminishment in the free volume due to TFFs serving as a filling material and formation of strong secondary bonds between components. Moreover, tensile strength and extension of the foams decreased with the increasing of TFFs, which caused by the occurrence of noteworthy restriction on the spatial alignment and orientation capability of polyurethane chains due to the lack of sufficient free volume allowing the chains to move freely. As for the compression tests, all the TFFs-loaded RPUFs depicted substantially lower performance due to TFFs interfering with the ordered organization of isocyanate domains. Moreover, impact test results showed that the addition of TFFs into RPUF matrix brought about the insufficient impact energy delocalization throughout the matrix due to the restriction on the mobility of polymer chains. Additionally, the remarkable diminishment in WVP was recorded due to the reduction in the number of vacancies and constitution of keratin composed of roundly 60% of hydrophilic protein (especially cystine). All in all, this study established a strong links between free volume and characteristics of TFFs-loaded RPUFs. Graphical Abstract
{"title":"Investigation of the relation between free volume and physico-mechanical performance in rigid polyurethane foam containing turkey feather fibers: Part 2","authors":"U. Soykan, Mustafa Khaleel, S. Çetin, U. Yahsi, C. Tav","doi":"10.1177/0021955X221144541","DOIUrl":"https://doi.org/10.1177/0021955X221144541","url":null,"abstract":"Rigid polyurethane foams (RPUFs) were modified with 0–15 wt.% turkey feather fibers (TFFs) produced from waste turkey feathers. One-shut free rising method was used for the production of TFFs-filled-RPUFs in a closed mold. The dependence of mechanical performance and water vapor permeability (WVP) feature of the final foams on TFFs loading was evaluated with free volume change. The free volume analysis was performed via Positron Annihilation Lifetime Spectroscopy (PALS), while the mechanical and WVP characteristics were determined with the use of the universal tester machines. PALS findings showed that the incorporation of TFFs with RPUF matrix caused the considerable diminishment in the free volume due to TFFs serving as a filling material and formation of strong secondary bonds between components. Moreover, tensile strength and extension of the foams decreased with the increasing of TFFs, which caused by the occurrence of noteworthy restriction on the spatial alignment and orientation capability of polyurethane chains due to the lack of sufficient free volume allowing the chains to move freely. As for the compression tests, all the TFFs-loaded RPUFs depicted substantially lower performance due to TFFs interfering with the ordered organization of isocyanate domains. Moreover, impact test results showed that the addition of TFFs into RPUF matrix brought about the insufficient impact energy delocalization throughout the matrix due to the restriction on the mobility of polymer chains. Additionally, the remarkable diminishment in WVP was recorded due to the reduction in the number of vacancies and constitution of keratin composed of roundly 60% of hydrophilic protein (especially cystine). All in all, this study established a strong links between free volume and characteristics of TFFs-loaded RPUFs. Graphical Abstract","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"25 1","pages":"893 - 915"},"PeriodicalIF":2.5,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74329804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-01DOI: 10.1177/0021955X221144546
Pedro Jorge Goes Lopes, Camila Berger, Henrique W Dalla Costa, Rodrigo Coldebella, Alencar Ibeiro de Oliveira, Nayara Lunkes, D. Gatto, Rafael de Avila Delucis, A. Missio
Natural tannin-based foams are three-dimensional porous materials. Many different formulations have been investigated in order to reach foams with improved performance and increased commercial attractiveness. In this sense, each different tannin pH may impart different physical and thermochemical properties to the foams, which has not yet been fully elucidated. In the present study, seven rigid tannin foams (formaldehyde/sulfur-free) were produced using tannin extracts with variable pH values (c.a. from 2.3 to 12.2). The most acidic tannin extracts (below 4.8) yielded tannin foams with the most lightweight (apparent density below 0.077 g.cm−3), homogeneous, and hydrophobic (water solubility below 23.5%) cellular-network architectures. Also, in most cases, the smaller the tannin pH, the higher the thermal stability of the foam. Further studies may address other technological requirements needed for thermal insulation applications. Graphical Abstract
{"title":"Effect of the pH value of tannin extracts on properties of classic tannin foams","authors":"Pedro Jorge Goes Lopes, Camila Berger, Henrique W Dalla Costa, Rodrigo Coldebella, Alencar Ibeiro de Oliveira, Nayara Lunkes, D. Gatto, Rafael de Avila Delucis, A. Missio","doi":"10.1177/0021955X221144546","DOIUrl":"https://doi.org/10.1177/0021955X221144546","url":null,"abstract":"Natural tannin-based foams are three-dimensional porous materials. Many different formulations have been investigated in order to reach foams with improved performance and increased commercial attractiveness. In this sense, each different tannin pH may impart different physical and thermochemical properties to the foams, which has not yet been fully elucidated. In the present study, seven rigid tannin foams (formaldehyde/sulfur-free) were produced using tannin extracts with variable pH values (c.a. from 2.3 to 12.2). The most acidic tannin extracts (below 4.8) yielded tannin foams with the most lightweight (apparent density below 0.077 g.cm−3), homogeneous, and hydrophobic (water solubility below 23.5%) cellular-network architectures. Also, in most cases, the smaller the tannin pH, the higher the thermal stability of the foam. Further studies may address other technological requirements needed for thermal insulation applications. Graphical Abstract","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"179 1","pages":"861 - 875"},"PeriodicalIF":2.5,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72791106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-01DOI: 10.1177/0021955X221144543
Christian Brütting, J. Dreier, C. Bonten, V. Altstädt, H. Ruckdäschel
Polymer foams offer high sustainable performance in terms of their lightweight potential, insulation and high specific mechanical properties. The foaming of polymers depends on the properties of gas-laden solids or liquids. For foaming in the solid state, the foaming temperature must be higher than the glass transition temperature of the saturated polymer system. Moreover, the knowledge of sorption conditions and thermal properties is crucial for foam formation. In this study, the correlation between the glass transition temperature and the sorption conditions was investigated. This comparison was made by determining the sorption behavior for different pressure levels and the corresponding glass transition temperature using a high-pressure differential scanning calorimetry. The time, pressure and CO2 content were varied. For the first time, the Chow model could be verified for PLA with a coordination number of 3.
{"title":"Glass transition of PLA-CO2 mixtures after solid-state saturation","authors":"Christian Brütting, J. Dreier, C. Bonten, V. Altstädt, H. Ruckdäschel","doi":"10.1177/0021955X221144543","DOIUrl":"https://doi.org/10.1177/0021955X221144543","url":null,"abstract":"Polymer foams offer high sustainable performance in terms of their lightweight potential, insulation and high specific mechanical properties. The foaming of polymers depends on the properties of gas-laden solids or liquids. For foaming in the solid state, the foaming temperature must be higher than the glass transition temperature of the saturated polymer system. Moreover, the knowledge of sorption conditions and thermal properties is crucial for foam formation. In this study, the correlation between the glass transition temperature and the sorption conditions was investigated. This comparison was made by determining the sorption behavior for different pressure levels and the corresponding glass transition temperature using a high-pressure differential scanning calorimetry. The time, pressure and CO2 content were varied. For the first time, the Chow model could be verified for PLA with a coordination number of 3.","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"19 1","pages":"917 - 931"},"PeriodicalIF":2.5,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89204433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-22DOI: 10.1177/0021955X221089434
Ye Liu, Xujian Chen, J. Pan, Y. Guan, Zheng Anna, D. Wei, Xiang Xu
In order to study the effect of microcrystalline cellulose on the reaction kinetics of polyurethane, in this work, the multi-scale microcrystalline cellulose was added to the foaming system of multifunctional polyether and multifunctional MDI polyurethane. While the chemical reaction was carried out, it was found through in situ FTIR combined with in situ rheological analysis that what was different from the usual inorganic fillers, the hydroxyl on the surface of the microcrystalline cellulose could preferentially react with MDI to generate urethane under the action of the catalyst. In the initial 5–6 min of the reaction, the reaction of soft segment chain growth was the main reaction. Then the main reaction quickly converted to the cross-linking reaction, which greatly increased the viscosity of the system. The addition of microcrystalline celluloses accelerated the improvement of the cross-linking degree and viscosity of the system. The higher the surface hydroxyl content of microcrystalline cellulose, the more significant this trend become. In addition, although the amount of microcrystalline cellulose added was different, the ratio of the reaction rate of the isocyanate group with the hydroxyl group and the amine group eventually tended to be constant, which indicated that there was a stable reactivity rate in the gradual addition reaction during the cross-linking reaction. Combined with SEM analysis, it was found that 25–60 μm microcrystalline cellulose with large hydroxyl content could act as a nucleating agent when the addition amount was less than 0.1%, which was beneficial to increase the cell density and reduce the pore size and improved the impact performance of the foam. The microcrystalline cellulose with a length of more than 90 μm continuously penetrated through several cell walls and destroyed integrity of the cell structure, which would consequently reduce the impact strength of the foam. This paper provided theoretical guidance for polyurethane modified by microcrystalline cellulose.
{"title":"Effect of microcrystalline cellulose on the preparation and performance of rigid polyurethane foam","authors":"Ye Liu, Xujian Chen, J. Pan, Y. Guan, Zheng Anna, D. Wei, Xiang Xu","doi":"10.1177/0021955X221089434","DOIUrl":"https://doi.org/10.1177/0021955X221089434","url":null,"abstract":"In order to study the effect of microcrystalline cellulose on the reaction kinetics of polyurethane, in this work, the multi-scale microcrystalline cellulose was added to the foaming system of multifunctional polyether and multifunctional MDI polyurethane. While the chemical reaction was carried out, it was found through in situ FTIR combined with in situ rheological analysis that what was different from the usual inorganic fillers, the hydroxyl on the surface of the microcrystalline cellulose could preferentially react with MDI to generate urethane under the action of the catalyst. In the initial 5–6 min of the reaction, the reaction of soft segment chain growth was the main reaction. Then the main reaction quickly converted to the cross-linking reaction, which greatly increased the viscosity of the system. The addition of microcrystalline celluloses accelerated the improvement of the cross-linking degree and viscosity of the system. The higher the surface hydroxyl content of microcrystalline cellulose, the more significant this trend become. In addition, although the amount of microcrystalline cellulose added was different, the ratio of the reaction rate of the isocyanate group with the hydroxyl group and the amine group eventually tended to be constant, which indicated that there was a stable reactivity rate in the gradual addition reaction during the cross-linking reaction. Combined with SEM analysis, it was found that 25–60 μm microcrystalline cellulose with large hydroxyl content could act as a nucleating agent when the addition amount was less than 0.1%, which was beneficial to increase the cell density and reduce the pore size and improved the impact performance of the foam. The microcrystalline cellulose with a length of more than 90 μm continuously penetrated through several cell walls and destroyed integrity of the cell structure, which would consequently reduce the impact strength of the foam. This paper provided theoretical guidance for polyurethane modified by microcrystalline cellulose.","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"41 1","pages":"739 - 755"},"PeriodicalIF":2.5,"publicationDate":"2022-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90750256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-13DOI: 10.1177/0021955X221095466
Bangli Yang, Lilu Zhou, Qiaohui Liu, Lijun Wang
In this study, N-aminoethylpiperazine (AEP)-functionalized and reduced graphene oxide (RGO) with different structures and properties was prepared by simply tuning the reduction time and then its effect on the rheological, curing and foaming behavior of epoxy resin was carefully investigated using the environment-friendly carbamate as a chemical foaming agent. As the reduction time of RGO increased, the reduction degree of RGO first increased and then levelled off but the grafted AEP was little affected by the reduction time. The addition of RGO undergoing long reduction time improved the viscoelasticity of epoxy/reduced graphene oxide (EP/RGO) composites but weakened the interfacial compatibility of RGO and EP. With increasing the reduction time of RGO, the cell size of EP/RGO composite foams decreased and the cell density increased. However, as compared with pure EP foam, the composite foams containing RGO with lower reduction degree had a larger cell size and a lower density. These results were attributed to the complicated effect of RGO, which not only acted as the heterogeneous nucleating and foaming agent but also affected the viscoelasticity of composites. In addition, as the reduction time of RGO increased, the initial thermal decomposition temperature, storage modulus at room temperature, electrical conductivity, thermal conductivity, and compressive properties of EP/RGO composite foams increased while the glass transition temperature remained unchanged. These results were related not only to the intrinsic properties and dispersion of RGO, but also to the density and cell morphology of the composite foams.
{"title":"Effect of reduction time of functionalized graphene oxide on the morphology and properties of epoxy composite foams","authors":"Bangli Yang, Lilu Zhou, Qiaohui Liu, Lijun Wang","doi":"10.1177/0021955X221095466","DOIUrl":"https://doi.org/10.1177/0021955X221095466","url":null,"abstract":"In this study, N-aminoethylpiperazine (AEP)-functionalized and reduced graphene oxide (RGO) with different structures and properties was prepared by simply tuning the reduction time and then its effect on the rheological, curing and foaming behavior of epoxy resin was carefully investigated using the environment-friendly carbamate as a chemical foaming agent. As the reduction time of RGO increased, the reduction degree of RGO first increased and then levelled off but the grafted AEP was little affected by the reduction time. The addition of RGO undergoing long reduction time improved the viscoelasticity of epoxy/reduced graphene oxide (EP/RGO) composites but weakened the interfacial compatibility of RGO and EP. With increasing the reduction time of RGO, the cell size of EP/RGO composite foams decreased and the cell density increased. However, as compared with pure EP foam, the composite foams containing RGO with lower reduction degree had a larger cell size and a lower density. These results were attributed to the complicated effect of RGO, which not only acted as the heterogeneous nucleating and foaming agent but also affected the viscoelasticity of composites. In addition, as the reduction time of RGO increased, the initial thermal decomposition temperature, storage modulus at room temperature, electrical conductivity, thermal conductivity, and compressive properties of EP/RGO composite foams increased while the glass transition temperature remained unchanged. These results were related not only to the intrinsic properties and dispersion of RGO, but also to the density and cell morphology of the composite foams.","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"25 1","pages":"777 - 796"},"PeriodicalIF":2.5,"publicationDate":"2022-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85522868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-11DOI: 10.1177/0021955X221092878
M. Walczak, J. Lubczak
Copolymerization of pentaerythritol with five equivalents of ɛ-caprolactone leads to tetra-functional branched oligomer terminated with hydroxyl groups. The product was characterized by elemental analysis, IR and NMR spectroscopy, gel permeation chromatography and physical methods to determine viscosity, density and surface tension. The oligomer was then used to obtain rigid polyurethane foam. The foam was characterized by physicochemical methods to determine: apparent density, water uptake, polymerization shrinkage, heat conductance coefficient, thermal stability, compression strength and biodegradation. The foam obtained from this oligomer have the properties similar to classic rigid polyurethane foams but enhanced thermal resistance. It can stand long time heating at 175°C, while its compression strength increases upon thermal exposure. The foam and oligomer are biodegradable; the oligomer is fully decomposed within 28 days in soil, while the foam obtained from it is in the same conditions degradable up to 28% of initial mass.
{"title":"ɛ-caprolactone and pentaerythritol derived oligomer for rigid polyurethane foams preparation","authors":"M. Walczak, J. Lubczak","doi":"10.1177/0021955X221092878","DOIUrl":"https://doi.org/10.1177/0021955X221092878","url":null,"abstract":"Copolymerization of pentaerythritol with five equivalents of ɛ-caprolactone leads to tetra-functional branched oligomer terminated with hydroxyl groups. The product was characterized by elemental analysis, IR and NMR spectroscopy, gel permeation chromatography and physical methods to determine viscosity, density and surface tension. The oligomer was then used to obtain rigid polyurethane foam. The foam was characterized by physicochemical methods to determine: apparent density, water uptake, polymerization shrinkage, heat conductance coefficient, thermal stability, compression strength and biodegradation. The foam obtained from this oligomer have the properties similar to classic rigid polyurethane foams but enhanced thermal resistance. It can stand long time heating at 175°C, while its compression strength increases upon thermal exposure. The foam and oligomer are biodegradable; the oligomer is fully decomposed within 28 days in soil, while the foam obtained from it is in the same conditions degradable up to 28% of initial mass.","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"30 1","pages":"757 - 775"},"PeriodicalIF":2.5,"publicationDate":"2022-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76337308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-03DOI: 10.1177/0021955X221087602
Virginia Martin Torrejon, Jim Song, Zhang Yu, Song Hang
Although most cellular polymers are made from thermoplastics using different foaming technologies, gelatin and many other natural polymers can form hydrogels and convert them to cellular solids using various techniques, many of which differ from traditional plastic foaming, and so does their resulting structures. Cellular solids from natural hydrogels are porous materials that often exhibit a combination of desirable properties, including high specific surface area, biochemical activity, as well as thermal and acoustic insulation properties. Among natural hydrogels, gelatin-based porous materials are widely explored due to their availability, biocompatibility, biodegradability and relatively low cost. In addition, gelatin-based cellular solids have outstanding properties and are currently subject to increasing scientific research due to their potential in many applications, such as biocompatible cellular materials or biofoams to facilitate waste treatment. This article aims at providing a comprehensive review of gelatin cellular solids processing and their processing-properties-structure relationship. The fabrication techniques covered include aerogels production, mechanical foaming, blowing agents use, 3D printing, electrospinning and particle leaching methods. It is hoped that the assessment of their characteristics provides compiled information and guidance for selecting techniques and optimization of processing conditions to control material structure and properties to meet the needs of the finished products.
{"title":"Gelatin-based cellular solids: Fabrication, structure and properties","authors":"Virginia Martin Torrejon, Jim Song, Zhang Yu, Song Hang","doi":"10.1177/0021955X221087602","DOIUrl":"https://doi.org/10.1177/0021955X221087602","url":null,"abstract":"Although most cellular polymers are made from thermoplastics using different foaming technologies, gelatin and many other natural polymers can form hydrogels and convert them to cellular solids using various techniques, many of which differ from traditional plastic foaming, and so does their resulting structures. Cellular solids from natural hydrogels are porous materials that often exhibit a combination of desirable properties, including high specific surface area, biochemical activity, as well as thermal and acoustic insulation properties. Among natural hydrogels, gelatin-based porous materials are widely explored due to their availability, biocompatibility, biodegradability and relatively low cost. In addition, gelatin-based cellular solids have outstanding properties and are currently subject to increasing scientific research due to their potential in many applications, such as biocompatible cellular materials or biofoams to facilitate waste treatment. This article aims at providing a comprehensive review of gelatin cellular solids processing and their processing-properties-structure relationship. The fabrication techniques covered include aerogels production, mechanical foaming, blowing agents use, 3D printing, electrospinning and particle leaching methods. It is hoped that the assessment of their characteristics provides compiled information and guidance for selecting techniques and optimization of processing conditions to control material structure and properties to meet the needs of the finished products.","PeriodicalId":15236,"journal":{"name":"Journal of Cellular Plastics","volume":"23 1","pages":"797 - 858"},"PeriodicalIF":2.5,"publicationDate":"2022-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76983646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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