solvent exchange
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Author(s):  
Nguyen Dang My Duyen ◽  
Nguyen Quang Duy ◽  
Ly Ngoc Bin

Solvent exchange is considered an effective method that changes the physicochemical properties of starch, especially the absorption. Ethanol concentration is one of the important influencing factors to form porous pores from the surface to inside starch granules. In this study, the effect of ethanol concentration on technical properties of starch treated by solvents were investigated. The ratio of ethanol/water was prepared at 1/9, 3/7, 5/5, 7/3 and 10/0 (w/w), respectively. Corn starch was treated by solvent at 8% concentration. Morphology, oil and water holding capacity, solubility, swelling power, viscosity, and transmittance were studied to elucidate the effect of the ethanol concentration on the morphological and technical properties of corn starch treated by solvent. As a result, starch treated by solvent with different concentrations tended to form wrinkles and pore from the surface to the inside of the starch granules during ethanol immersion. Therefore, the oil and water holding capacity, solubility, swelling and viscosity of the solvent-treated starch samples increase as the concentration of ethanol increases. Otherwise, the transmittance of starch glues tends to decrease when the ethanol concentration increases.


2021 ◽  
Author(s):  
Sachini Perera ◽  
Alejandra Durand-Silva ◽  
Ashele Remy ◽  
Shashini Diwakara ◽  
Ronald Smaldone

Vat photopolymerization is a versatile 3D printing method that produces parts using polymeric materials with uniform mechanical properties, high quality surface finish and high-resolution features. However, it is challenging to make composite materials with vat photopolymerization mainly due to the imperfect filler dispersion in the photo resin. Herein, we describe a methodology to incorporate aramid nanofibers (ANFs) into a 3D printable photoresin as a dispersion, followed by a solvent exchange process that limits anisotropic shrinkage and cracking of the printed polymer. By incorporating 0.60 wt.% of ANFs, both the tensile strength and toughness increased by 264 % and 219 % respectively, while the Young’s modulus had a 406 % increase compared to the control photoresin.


Author(s):  
Changyong Cai ◽  
Shuanggen Wu ◽  
Zhijian Tan ◽  
Fenfang Li ◽  
Shengyi Dong
Keyword(s):  

2021 ◽  
pp. 2100852
Author(s):  
Qiantao Song ◽  
Yining Chen ◽  
Yanping Huang ◽  
Weihua Dan ◽  
Meng Wang ◽  
...  

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2631
Author(s):  
Kriangsak Kraiwattanawong ◽  
Noriaki Sano ◽  
Hajime Tamon

Carbon/carbon (C/C) composite xerogels dried by evaporation were prepared in this study to observe the change of their porous properties and their morphology by nitrogen sorption apparatus and a scanning electron microscope. Resorcinol and formaldehyde (RF) sols as a matrix phase and cotton fibers (CF) as a dispersed phase were mixed and gelated to be CF/RF composite hydrogels. The composite hydrogels were exchanged by t-butanol (TBA), dried by evaporation at 50 °C, and carbonized at 1000 °C to become the C/C composite xerogels. The results show that the CF addition does not decrease the mesoporous properties of the C/C composite xerogels. Moreover, the CF addition can alleviate the pore shrinkage, and it can maintain the mesopore structure. The mesopore size and the micropore size of C/C composites are insignificantly changed because the CF addition and the solvent exchange using TBA may suppress the pore shrinkage despite the gas-liquid interface existing during the evaporation drying.


2021 ◽  
pp. 128673
Author(s):  
Claudia Roman ◽  
Moisés García-Morales ◽  
María E. Eugenio ◽  
David Ibarra ◽  
Raquel Martín-Sampedro ◽  
...  

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