Polyacrylamide/Chitosan-Based Conductive Double Network Hydrogels with Outstanding Electrical and Mechanical Performance at Low Temperatures

Author(s):  
Jing Cong ◽  
Zhiwei Fan ◽  
Shaoshan Pan ◽  
Jie Tian ◽  
Weizhen Lian ◽  
...  
2021 ◽  
Vol 25 (109) ◽  
pp. 88-97
Author(s):  
Carlos Magno Chavarry Vallejos ◽  
Liliana Janet Chavarría Reyes ◽  
Xavier Antonio Laos Laura ◽  
Andrés Avelino Valencia Gutiérrez ◽  
Enriqueta Pereyra Salardi ◽  
...  

El presente artículo tiene como objetivo determinar la influencia de la adición del dióxido de titanio (TiO2) en el mortero de cemento Pórtland Tipo I. La investigación es descriptiva, correlacional, explicativo, con diseño experimental, longitudinal, prospectivo y estudio de cohorte. Se elaboró una mezcla patrón y tres mezclas de mortero con 5%, 7.5% y 10% de contenido de TiO2 como reemplazo del volumen de cemento para las propiedades autolimpiantes se realizó el ensayo de rodamina e intemperismo. La incorporación de dióxido de titanio disminuyó la resistencia a la compresión, incrementó la fluidez y tasa de absorción de agua; la prueba de rodamina dio que el mortero sin actividad fotocatalítico no contenía TiO2 porque no cumple con los factores de fotodegradación R4 y R26. Mediante la exposición de paneles al intemperismo favoreciendo la propiedad autolimpiante de los morteros con adición de TiO2 (5%). Palabras Clave: Actividad foto catalítico, dióxido de titanio, factores de fotodegradación, propiedades mecánicas y autolimpiante. Referencias [1]E. Medina and H. Pérez, “Influencia del fotocatalizador dióxido de titanio en las propiedades autolimpiables y mecánicas del mortero de cemento - arena 1:4 - Cajamarca,” Universidad Nacional de Cajamarca, 2017. [2]G. Abella, “Mejora de las propiedades de materiales a base de cemento que contienen TiO 2 : propiedades autolimpiantes,” Universidad Politécnica de Madrid, 2015. [3]J. Gonzalez, “El Dióxido de titanio como material fotocatalitico y su influencia en la resistencia a la compresión en Morteros,” Universidad de San Buenaaventura Seccional Bello, 2015. [4]D. Jimenez and J. Moreno, “Efecto del reemplazo de cemento portland por el dioido de titanio en las propiedades mecanicas del mortero,” Pontificia Universidad Javeriana, 2016. [5]L. Wang, H. Zhang, and Y. Gao, “Effect of TiO2 nanoparticles on physical and mechanical properties of cement at low temperatures,” Adv. Mater. Sci. Eng., 2018, doi: 10.1155/2018/8934689. [6]Comisión de Normalización y de Fiscalización de Barreras Comerciales no Arancelares, Norma Técnica Peruana. Perú, 2013, p. 29. [7]ASTM Internacional, “ASTM C150,” 2021. https://www.astm.org/Database.Cart/Historical/C150-07-SP.htm. [8]M. Issa, “( current astm c150 / aashto m85 ) with limestone and process addition ( ASTM C465 / AASHTO M327 ) on the performance of concrete for pavement and Prepared By,” 2014. [9]S. Zailan, N. Mahmed, M. Abdullah, A. Sandu, and N. Shahedan, “Review on characterization and mechanical performance of self-cleaning concrete,” MATEC Web Conf., vol. 97, pp. 1–7, 2017, doi: 10.1051/matecconf/20179701022. [10]C. Chavarry, L. Chavarría, A. Valencia, E. Pereyra, J. Arieta, and C. Rengifo, “Hormigón reforzado con vidrio molido para controlar grietas y fisuras por contracción plástica,” Pro Sci., vol. 4, no. 31, pp. 31–41, 2020, doi: 10.29018/issn.2588-1000vol4iss31.2020pp31-41. [11]D. Tobaldi, “Materiali ceramici per edilizia con funzionalità fotocatalitica,” Università di Bologna, 2009. [12]Norme UNI, “Norma Italiana UNI 11259,” 2016. http://store.uni.com/catalogo/uni-11259-2008?josso_back_to=http://store.uni.com/josso-security-check.php&josso_cmd=login_optional&josso_partnerapp_host=store.uni.com. [13]E. Grebenisan, H. Szilagyi, A. Hegyi, C. Mircea, and C. Baera, “Directory lines regarding the desing and production of self-cleaning cementitious composites,” Sect. Green Build. Technol. Mater., vol. 19, no. 6, 2019. [14]M. Kaszynska, “The influence of TIO2 nanoparticles on the properties of self-cleaning cement mortar,” Int. Multidiscip. Sci. GeoConference SGEM, pp. 333–341, 2018.


Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3333 ◽  
Author(s):  
Niu ◽  
Zhang ◽  
Shen ◽  
Sheng ◽  
Fu ◽  
...  

A new design strategy was proposed to improve the mechanical performance of double network (DN) hydrogels by introducing polyhydroxy compounds into the DN structure and form a physically linked double network through the interaction of hydrogen bonding. Herein, agar/poly(acrylic acid)/hydroxyethyl cellulose composite hydrogels could be prepared by a simple one-pot method. The resulting hydrogels exhibit highly mechanical properties and excellent recoverability, which have potential applications in biomedical fields.


2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Meimei Song ◽  
Chuanlin Wang

Glass fibre reinforced cement (GFRC) is a composite material with great ductility but it undergoes severe strength and ductility degradation with ageing. Calcium sulfoaluminate (CSA) cement is low carbon cement, and more importantly, it exhibits great potential to produce more ductile and durable GFRC. This study focuses on mechanical performance, e.g., compressive strength, stress-strain curve, and freeze-thaw resistance of CSA/GFRC as well as its microstructural characteristics under low temperatures. XRD was applied to investigate the hydration mechanism of CSA cement under −5°C, 0°C, and 5°C. It was found out that low-temperature environments have very little effect on the type of hydration products, and the main hydration product of hydrated CSA cement cured under low temperatures is ettringite. Moreover, low-curing temperatures have an adverse effect on the compressive strength developments of CSA/GFRC but the strength difference compared with that under 20°C reduces gradually with increasing curing ages. In terms of bending performance, both ultimate tensile strength and ultimate strain value indicate considerable degradation with ageing under low temperatures after 14 d. The ultimate strain value reduces to 0.34% at −5°C, 0.39% at 0°C, and 0.44% at 5°C compared with 0.51% for that cured at 20°C for 28 d. The tensile strength of samples cured at −5°C for 28 d is only 15.2 MPa, taking up only 40% of that under 20°C. CSA/GFRC also demonstrated great capability in the antifreeze-thaw performance, and the corresponding strength remains 95.9%, 94.7%, 94.2%, and 94.3%, respectively, for that cured under 20°C, 5°C, 0°C, and −5°C after 50 freeze-thaw cycles. Microstructural studies reveal that densification of the interfilamentary space with intermixtures of C-A-S-H and ettringite is the main reason that causes the degradation of CSA/GFRC, which may result in loss on flexibility when forces are applied, therefore reducing the post-peak toughness to some extent.


2021 ◽  
Author(s):  
Marshall Allen ◽  
Rahul Sujanani ◽  
Alyssa Chamseddine ◽  
Benny Freeman ◽  
Zachariah Page

Water swollen polymer networks are attractive for applications ranging from tissue regeneration to water purification. For water purification, charged polymers provide excellent ion separation properties. However, many ion exchange membranes (IEMs) are brittle, necessitating the use of thick support materials that ultimately decrease throughput. To this end, a series of double network hydrogels (DNHs), synthesized with varied composition to decrease water content, are examined as robust membrane materials for water purification. One network contains fixed anionic charges, while the other comprises a copolymer with different ratios of hydrophobic ethyl acrylate (EA) and hydrophilic dimethyl acrylamide (DMA) repeat units. Characterizing water content and mechanical performance in free standing DNH films reveals a ~5× decrease in water content, while increasing ultimate stress and strain by ~3.5× and ~4.5× for 90:5 EA:DMA relative to pure DMA. Salt transport properties relevant to water purification, including permeability, solubility, and diffusivity, are measured and show improved performance upon reducing water content. Overall, the ability to simultaneously reduce water content, increase mechanical integrity, and decrease salt transport rates highlights the potential of DNHs for membrane applications.


Polymer ◽  
2018 ◽  
Vol 153 ◽  
pp. 607-615 ◽  
Author(s):  
Meng Zhang ◽  
Xiuyan Ren ◽  
Lijie Duan ◽  
Guanghui Gao

2021 ◽  
Author(s):  
Marshall Allen ◽  
Rahul Sujanani ◽  
Alyssa Chamseddine ◽  
Benny Freeman ◽  
Zachariah Page

Water swollen polymer networks are attractive for applications ranging from tissue regeneration to water purification. For water purification, charged polymers provide excellent ion separation properties. However, many ion exchange membranes (IEMs) are brittle, necessitating the use of thick support materials that ultimately decrease throughput. To this end, a series of double network hydrogels (DNHs), synthesized with varied composition to decrease water content, are examined as robust membrane materials for water purification. One network contains fixed anionic charges, while the other comprises a copolymer with different ratios of hydrophobic ethyl acrylate (EA) and hydrophilic dimethyl acrylamide (DMA) repeat units. Characterizing water content and mechanical performance in free standing DNH films reveals a ~5× decrease in water content, while increasing ultimate stress and strain by ~3.5× and ~4.5× for 90:5 EA:DMA relative to pure DMA. Salt transport properties relevant to water purification, including permeability, solubility, and diffusivity, are measured and show improved performance upon reducing water content. Overall, the ability to simultaneously reduce water content, increase mechanical integrity, and decrease salt transport rates highlights the potential of DNHs for membrane applications.


2011 ◽  
Vol 64 (8) ◽  
pp. 1007 ◽  
Author(s):  
Sina Naficy ◽  
Hugh R. Brown ◽  
Joselito M. Razal ◽  
Geoffrey M. Spinks ◽  
Philip G. Whitten

In this review we highlight new developments in tough hydrogel materials in terms of their enhanced mechanical performance and their corresponding toughening mechanisms. These mechanically robust hydrogels have been developed over the past 10 years with many now showing mechanical properties comparable with those of natural tissues. By first reviewing the brittleness of conventional synthetic hydrogels, we introduce each new class of tough hydrogel: homogeneous gels, slip-link gels, double-network gels, nanocomposite gels and gels formed using poly-functional crosslinkers. In each case we provide a description of the fracture process that may be occurring. With the exception of double network gels where the enhanced toughness is quite well understood, these descriptions remain to be confirmed. We also introduce material property charts for conventional and tough synthetic hydrogels to illustrate the wide range of mechanical and swelling properties exhibited by these materials and to highlight links between these properties and the network topology. Finally, we provide some suggestions for further work particularly with regard to some unanswered questions and possible avenues for further enhancement of gel toughness.


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