scholarly journals Analysis of the Effect of Processing Conditions on Physical Properties of Thermally Set Cellulose Hydrogels

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1066 ◽  
Author(s):  
Tim Huber ◽  
Sean Feast ◽  
Simone Dimartino ◽  
Wanwen Cen ◽  
Conan Fee

Cellulose-based hydrogels were prepared by dissolving cellulose in aqueous sodium hydroxide (NaOH)/urea solutions and casting it into complex shapes by the use of sacrificial templates followed by thermal gelation of the solution. Both the gelling temperatures used (40–80 °C), as well as the method of heating by either induction in the form of a water bath and hot press or radiation by microwaves could be shown to have a significant effect on the compressive strength and modulus of the prepared hydrogels. Lower gelling temperatures and shorter heating times were found to result in stronger and stiffer gels. Both the effect of physical cross-linking via the introduction of additional non-dissolving cellulosic material, as well as chemical cross-linking by the introduction of epichlorohydrin (ECH), and a combination of both applied during the gelation process could be shown to affect both the mechanical properties and microstructure of the hydrogels. The added cellulose acts as a physical-cross-linking agent strengthening the hydrogen-bond network as well as a reinforcing phase improving the mechanical properties. However, chemical cross-linking of an unreinforced gel leads to unfavourable bonding and cellulose network formation, resulting in drastically increased pore sizes and reduced mechanical properties. In both cases, chemical cross-linking leads to larger internal pores.

Langmuir ◽  
2009 ◽  
Vol 25 (24) ◽  
pp. 13809-13819 ◽  
Author(s):  
Thomas Boudou ◽  
Thomas Crouzier ◽  
Rachel Auzély-Velty ◽  
Karine Glinel ◽  
Catherine Picart

2013 ◽  
Vol 457-458 ◽  
pp. 227-230
Author(s):  
Gui Hua Chen ◽  
Dan Dan Wang

The rice-straw particle /HDPE composites were made by compression molding process. Effects of the content of the rice-straw particle, the dosage of the titanate coupling agent and the time of hot-press were analyzed. Mechanical properties of the composites were tested, such as MOR, MOE by universal material testing machine. The result showed that rice-straw particle /HDPE composites have relatively good mechanical properties. The effect of the content of the rice-straw particle on the MOR and MOE of rice-straw particle /HDPE composites are very significant.The mechanical properties of the composite material improved by adding titanate coupling agent. The optimized processing conditions are that the content of the rice-straw particle is 50%,the dosage of the titanate coupling agent is 3%,the time of hot-press is 4 min.


Langmuir ◽  
2018 ◽  
Vol 34 (21) ◽  
pp. 6109-6116 ◽  
Author(s):  
A. Salmatonidis ◽  
J. Hesselbach ◽  
G. Lilienkamp ◽  
T. Graumann ◽  
W. Daum ◽  
...  

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1787 ◽  
Author(s):  
Dae Hoon Lee ◽  
Atsushi Tamura ◽  
Yoshinori Arisaka ◽  
Ji-Hun Seo ◽  
Nobuhiko Yui

Tough mechanical properties are generally required for tissue substitutes used in regeneration of damaged tissue, as these substitutes must be able to withstand the external physical force caused by stretching. Gelatin, a biopolymer derived from collagen, is a biocompatible and cell adhesive material, and is thus widely utilized as a component of biomaterials. However, the application of gelatin hydrogels as a tissue substitute is limited owing to their insufficient mechanical properties. Chemical cross-linking is a promising method to improve the mechanical properties of hydrogels. We examined the potential of the chemical cross-linking of gelatin hydrogels with carboxy-group-modified polyrotaxanes (PRXs), a supramolecular polymer comprising a poly(ethylene glycol) chain threaded into the cavity of α-cyclodextrins (α-CDs), to improve mechanical properties such as stretchability and toughness. Cross-linking gelatin hydrogels with threading α-CDs in PRXs could allow for freely mobile cross-linking points to potentially improve the mechanical properties. Indeed, the stretchability and toughness of gelatin hydrogels cross-linked with PRXs were slightly higher than those of the hydrogels with the conventional chemical cross-linkers 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS). In addition, the hysteresis loss of gelatin hydrogels cross-linked with PRXs after repeated stretching and relaxation cycles in a hydrated state was remarkably improved in comparison with that of conventional cross-linked hydrogels. It is considered that the freely mobile cross-linking points of gelatin hydrogels cross-linked with PRXs attenuates the stress concentration. Accordingly, gelatin hydrogels cross-linked with PRXs would provide excellent mechanical properties as biocompatible tissue substitutes exposed to a continuous external physical force.


Soft Matter ◽  
2021 ◽  
Author(s):  
Libby Jane Marshall ◽  
Olga Matsarskaia ◽  
Ralf Schweins ◽  
Dave Adams

Exposure of lysine-containing peptide-based gelators to the cross-linking agent glutaraldehyde allows tuning of gel mechanical properties. The effect of cross-linking depends on the position of the lysine residue in the...


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