scholarly journals A Robust, Tough and Multifunctional Polyurethane/Tannic Acid Hydrogel Fabricated by Physical-Chemical Dual Crosslinking

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 239 ◽  
Author(s):  
Jie Wen ◽  
Xiaopeng Zhang ◽  
Mingwang Pan ◽  
Jinfeng Yuan ◽  
Zhanyu Jia ◽  
...  

Commonly synthetic polyethylene glycol polyurethane (PEG–PU) hydrogels possess poor mechanical properties, such as robustness and toughness, which limits their load-bearing application. Hence, it remains a challenge to prepare PEG–PU hydrogels with excellent mechanical properties. Herein, a novel double-crosslinked (DC) PEG–PU hydrogel was fabricated by combining chemical with physical crosslinking, where trimethylolpropane (TMP) was used as the first chemical crosslinker and polyphenol compound tannic acid (TA) was introduced into the single crosslinked PU network by simple immersion process. The second physical crosslinking was formed by numerous hydrogen bonds between urethane groups of PU and phenol hydroxyl groups in TA, which can endow PEG–PU hydrogel with good mechanical properties, self-recovery and a self-healing capability. The research results indicated that as little as a 30 mg·mL−1 TA solution enhanced the tensile strength and fracture energy of PEG–PU hydrogel from 0.27 to 2.2 MPa, 2.0 to 9.6 KJ·m−2, respectively. Moreover, the DC PEG–PU hydrogel possessed good adhesiveness to diverse substrates because of TA abundant catechol groups. This work shows a simple and versatile method to prepare a multifunctional DC single network PEG–PU hydrogel with excellent mechanical properties, and is expected to facilitate developments in the biomedical field.

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Haoliang Huang ◽  
Guang Ye

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.


2020 ◽  
Vol 44 (10) ◽  
pp. 4061-4070 ◽  
Author(s):  
Yayu Li ◽  
Tianyang Zhou ◽  
Zhangyong Yu ◽  
Fei Wang ◽  
Dongjian Shi ◽  
...  

Two kinds of dual crosslinking hydrogels have adjustable mechanical properties, self-healing and self-recovery performances.


2020 ◽  
Vol 8 (21) ◽  
pp. 4660-4671 ◽  
Author(s):  
Kun Li ◽  
Jingxi Wang ◽  
Ping Li ◽  
Yubo Fan

Ternary hydrogels with tunable mechanical properties were prepared based on the synergistic effects of hydrogen bonds and imine bonds.


2017 ◽  
Vol 30 (10) ◽  
pp. 1159-1168 ◽  
Author(s):  
Animesh Sinha ◽  
Nazrul Islam Khan ◽  
Subhankar Das ◽  
Jiawei Zhang ◽  
Sudipta Halder

The effect of reactive (polyethylene glycol) and non-reactive (toluene) diluents on thermal and mechanical properties (tensile strength, hardness and fracture toughness) of diglycidyl ether of bisphenol A epoxy resin (cured by triethylenetetramine) was investigated. The thermal stability and mechanical properties of the epoxy resin modified with reactive and non-reactive diluents at different wt% were investigated using thermo-gravimetric analyser, tensile test, hardness test and single-edge-notched bend test. A minor variation in thermal stability was observed for epoxy resin after addition of polyethylene glycol and toluene at 0.5 wt%; however, further addition of reactive and non-reactive diluents diminished the thermal stability. The addition of 10 wt% of polyethylene glycol in epoxy resin significantly enhances the tensile strength (∼12%), hardness (∼14%) and fracture toughness (∼24%) when compared to that of neat epoxy resin. In contrast, major drop in mechanical performance was observed after addition of toluene in epoxy. Furthermore, fracture surfaces were investigated under field emission scanning electron microscope to elucidate the failure mechanism.


Author(s):  
M. N. Meiirbekov ◽  
◽  
M. B. Ismailov ◽  

The paper presents published data on the effect of rubber elastomers on the strength properties of epoxy resin (ES) and carbon fiber. The introduction of 10% rubbers into ES ED-20 leads to an increase in compressive strength by 50%, tensile strength by 51%, impact strength by 133% and elongation by 128%. The optimal content of rubber with carboxyl groups for the OLDEN mixture was 10-12.5%, while the increase in compressive strength was 48%, impact strength - 73% and elongation - 187%. For DER 331 resin, the study was conducted with two hardeners Piperidine and DETA. The best results for Piperidine hardener were obtained on rubber with hydroxyl groups, with its optimal content of 2.5%, impact strength increased by 170%. For the hardener DETA, the best results were obtained on rubber with carboxyl groups at its optimal content of 10%, the increase in impact strength was 66%. When modifying carbon fiber with rubbers, it leads to a significant increase in the yield strength in tension by 42%, the modulus of elasticity in bending by 63%, and with a slight loss of impact strength.


Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1674 ◽  
Author(s):  
Jing-Yu Liang ◽  
Se-Ra Shin ◽  
Soo-Hyoung Lee ◽  
Dai-Soo Lee

With limited biomass that can be currently utilized as a renewable resource, it is important to develop a method to convert biomass into materials that can replace fossil fuel product. In this paper, eugenol, a bio-based allyl chain-substituted guaiacol, was used to synthesize self-healable copolymers. Eugenol terminated polyurethane prepolymer (ETPU) was synthesized from eugenol and polyurethane prepolymers terminated with isocyanate groups. ETPU contained two allyl groups. Self-healing copolymer networks were obtained by copolymerization of ETPU and styrene monomer via free radical polymerization. Effects of ETPU content on the properties of copolymers were then studied. These copolymers containing ETPU exhibited good thermal stability and mechanical properties. These copolymers showed higher tensile strength and elongation at break than PS. Their maximum tensile strength reached 19 MPa. In addition, these copolymers showed self-healing property at elevated temperature due to the reversible nature of urethane units in ETPU.


2012 ◽  
Vol 217-219 ◽  
pp. 517-521 ◽  
Author(s):  
Hong Ling Yi ◽  
Ting Wei ◽  
Lin Heng ◽  
Bai Cun Zheng

In this paper the closed-cell sponge of chloroprene rubber(CR) were produced by foaming agent Azodicarbonamide (AC) and Oxybis (benzene sulfonyl) hydrazide (OBSH). The blend blowing agent AC/OBSH was more effective than the pure AC as it could produce chloroprene foam with greater cell porosity, more uniform and better cell distributions. The CR foam prepared with AC/OBSH had better tensile strength and tear strength than pure AC, but higher Shore C hardness. The Polyethyene glycol (PEG) modified Zinc Oxide (ZnO) could accelerate curing and foam process simultaneously. Increase the content of PEG, CR foam has bigger swell ratio, smaller cell size, and better softness.


2011 ◽  
Vol 197-198 ◽  
pp. 1306-1309 ◽  
Author(s):  
Feng Yuan Huang ◽  
Yan Yu ◽  
Xiao Jie Wu

Cellulose Oleate (CO) was synthesized by acylating cellulose in homogeneous system with p-toluenesulfonyl chloride (Tos-Cl) and oleic acid. The structure of CO was characterized by FT-IR, and degree of substitution (DS) of CO was determined by saponification method. Substituent distribution analysis was carried out with curve-fitting method, and the results indicated that acyl reaction of cellulose with oleic acid preferred to react at primary hydroxyl groups. The CO converted into films by casting. The mechanical properties of CO films were investigated. With the increase of DS, the tensile strength decreases gradually, but the tensile strain increases apparently.


2011 ◽  
Vol 299-300 ◽  
pp. 460-465 ◽  
Author(s):  
Li Zhang ◽  
Xiu Ping Dong ◽  
Hao Chen

By designing different formulations of composites and adopting optimized technology including extrusion and molding, the different composites with various content microcapsules were prepared. The results of the tensile tests show that with the increasing content of self-healing microcapsules in the glass fiber reinforced nylon composites, the mechanical properties of the composites will change, i.e. tensile strength, elastic modulus will decrease. But there is little effect on the mechanical properties of the composite gears if the content of self-healing microcapsules is less than 3.5%, and the technology of self-healing microcapsules used in the polymer composite gear is feasible.


2018 ◽  
Vol 51 (5) ◽  
pp. 406-420 ◽  
Author(s):  
Nuttida Srirachya ◽  
Takaomi Kobayashi ◽  
Kumarjyoti Roy ◽  
Kanoktip Boonkerd

In this article, thermoreversible covalent cross-linking of maleated natural rubber (MNR) with glycerol was studied. Firstly, NR was grafted with maleic anhydride using a reactive processing method. The result showed that MNR was successfully obtained without the addition of initiator. The highest grafting was 1.76%. Secondly, the obtained MNR was dissolved in toluene and then mixed with glycerol, which is used in this study as the thermoreversible cross-linking agent. Fourier transform infrared spectra of the casted MNR film mixed with glycerol showed that upon heating, covalent ester cross-links were formed via the reaction of succinic anhydride ring with hydroxyl groups of glycerol. The swelling test indicated that the swelling index (%) decreased with increasing glycerol loading. This indicated that the degree of cross-linking directly depended on the amount of glycerol. The tensile strength and modulus were significantly improved upon increasing the level of cross-linking. The MNR cross-linked with glycerol can be remolded at 150°C more than three times. After remolding, the mechanical properties decreased with increasing recycling round.


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