Double-Network Physical Cross-Linking Strategy To Promote Bulk Mechanical and Surface Adhesive Properties of Hydrogels

2019 ◽  
Vol 52 (24) ◽  
pp. 9512-9525 ◽  
Author(s):  
Li Tang ◽  
Dong Zhang ◽  
Liang Gong ◽  
Yanxian Zhang ◽  
Shaowen Xie ◽  
...  
Keyword(s):  
Cross Linking ◽  
Adhesive Properties ◽  
Double Network

Surface and Adhesive Properties of Low-Density Polyethylene after Radiation Cross-Linking

2014 ◽  
Vol 606 ◽  
pp. 265-268 ◽  
Author(s):  
Martin Bednarik ◽  
David Manas ◽  
Miroslav Manas ◽  
Martin Ovsik ◽  
Jan Navratil ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Performance ◽  
Chemical Properties ◽  
Low Density Polyethylene ◽  
Cross Linking ◽  
Low Density ◽  
X Rays ◽  
Radiation Processing ◽  
Adhesive Properties ◽  
Γ Rays

Radiation cross-linking gives inexpensive commodity plastics and technical plastics the mechanical, thermal, and chemical properties of high-performance plastic. This upgrading of the plastics enables them to be used in conditions which they would not be able to with stand otherwise. The irradiation cross-linking of thermoplastic materials via electron beam or cobalt 60 (gammy rays) is performed separately, after processing. Generally, ionizing radiation includes accelerated electrons, gamma rays and X-rays. Radiation processing with an electron beam offers several distinct advantages when compared with other radiation sources, particularly γ-rays and x-rays. The process is very fast, clean and can be controlled with much precision. There is no permanent radioactivity since the machine can be switched off. In contrast to γ-rays and x-rays, the electron beam can steered relatively easily, thus allowing irradiation of a variety of physical shapes. The energy-rich beta rays trigger chemical reactions in the plastics which results in networking of molecules (comparable to the vulcanization of rubbers which has been in industrial use for so long). The energy from the rays is absorbed by the material and cleavage of chemical bonds takes place. This releases free radicals which in next phase from desired molecular bonds. This article describes the effect of radiation cross-linking on the surface and adhesive properties of low-density polyethylene.

Selective De-Cross-Linking of Transformable, Double-Network Hydrogels: Preparation, Structural Conversion, and Controlled Release

2018 ◽  
Vol 10 (49) ◽  
pp. 42985-42991 ◽  
Author(s):  
Doyoung Jung ◽  
Kyoung Min Lee ◽  
Ji Young Chang ◽  
Misun Yun ◽  
Hak-Jong Choi ◽  
...  
Keyword(s):  
Controlled Release ◽  
Cross Linking ◽  
Structural Conversion ◽  
Double Network

Surface Energy of Selected Polyolefins after Radiation Cross-Linking

2015 ◽  
Vol 752-753 ◽  
pp. 342-345
Author(s):  
Martin Bednarik ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
Jan Navratil ◽  
...  
Keyword(s):  
Surface Energy ◽  
High Density Polyethylene ◽  
Beta Radiation ◽  
Low Density Polyethylene ◽  
Cross Linking ◽  
Bonded Joints ◽  
Adhesive Properties ◽  
High Quality ◽  
Measurement Results ◽  
Untreated Material

In this study there was found that radiation cross-linking increased the surface energy of high-density polyethylene (HDPE), and low-density polyethylene (LDPE). Surface energy affects the wettability of the surface and is very important for creating of high-quality bonded joints. The measurement results indicated that radiation cross-linking was a very effective tool for the improvement of adhesive properties and increased the surface energy of selected polyolefins. Surfaces of selected materials with ionizing beta radiation with doses of 0, 33, 66, 99, 132, 165, and 198 kGy were irradiated. The best results were achieved by irradiation at dose of 165 kGy. The surface energy after irradiation was increased up to 100 % compared to untreated material.

Effects of low-energy electron bombardment on the surface chemical structure and adhesive properties of polytetrafluoroethylene (PTFE)

1986 ◽  
Vol 1 (5) ◽  
pp. 717-723 ◽  
Author(s):  
J.A. Kelber ◽  
J.W. Rogers ◽  
S.J. Ward
Keyword(s):  
High Vacuum ◽  
Nitrogen Adsorption ◽  
Electron Bombardment ◽  
Polymer Chains ◽  
Ultra High Vacuum ◽  
Cross Linking ◽  
Cohesive Failure ◽  
Adhesive Properties ◽  
Rate Determining Step ◽  
Adsorption Of Nitrogen

The x-ray photoemission studies of polytetrafluoroethylene (PTFE) bombarded by lowenergy electrons in ultra-high vacuum conditions indicate that the major chemical changes induced by electron bombardment are defluorination of the surface and cross-linking of the polymer chains. The same electron bombardment process, when performed in the presence of 1×10−6 Torr ND3, also results in the adsorption of nitrogen-containing groups at the surface. The rate of nitrogen adsorption is linear for short electron bombardment times while the rates of defluorination and cross-linking are roughly exponential. However, at long bombardment times, the rates of nitrogen uptake, defluorination, and cross-linking become zero at the same time, indicating that defluorination of the surface is the rate-determining step in electron beam-induced adsorption of nitrogen-containing species. Regardless of whether the bombardment is carried out in ultra-high vacuum or in the presence of ND3, the maximum modification depth is less than 30 Å. Pull tests performed on PTFE samples bombarded by electrons in ultra-high vacuum, then removed into air and bonded to epoxy show epoxy-PTFE joint strengths of 280–360 1b/in.2 (psi), are compared to zero psi for untreated PTFE and ≃2000 psi for cohesive failure within the PTFE layer.

Preparation of single or double-network chitosan/poly(vinyl alcohol) gel films through selectively cross-linking method

2009 ◽  
Vol 77 (4) ◽  
pp. 718-724 ◽  
Author(s):  
Songmiao Liang ◽  
Linshu Liu ◽  
Qingrong Huang ◽  
Kit L. Yam
Keyword(s):  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Cross Linking ◽  
Double Network

A Model for the Mullins Effect in Multinetwork Elastomers

2017 ◽  
Vol 84 (12) ◽  
Author(s):  
Mattia Bacca ◽  
Costantino Creton ◽  
Robert M. McMeeking
Keyword(s):  
Damage Model ◽  
Hydrostatic Compression ◽  
Cross Linking ◽  
Mullins Effect ◽  
Maximum Strain ◽  
Double Network ◽  
Proposed Model ◽  
Damage Process ◽  
Composite Stiffness ◽  
Highly Loaded

Double and triple network (TN) elastomers can be made by infusing monomers into a single network (SN) polymer, causing it to swell, and then polymerizing and cross-linking the monomers. The result is a double network (DN) elastomer in which one network is stretched and the other is in hydrostatic compression. TN systems are made by repeating the process starting with the DN material. The multinetwork (MN) elastomers exhibit a Mullins effect in which softening occurs upon a first cycle of loading, with the elastomer stiffness recovered above the previous maximum strain. The Mullins effect is attributed to rupture of the stretched network, eliminating the constraint on the compressed network, thereby motivating straining at the lower stiffness of the remaining material. A model for this process is developed, based on the previous work of Horgan et al. (2004, “A Theory of Stress Softening of Elastomers Based on Finite Chain Extensibility,” Proc. R. Soc. A, 460(2046), pp. 1737–1754). In the proposed model, a composite stiffness for the MN system is developed and a damage process introduced to degrade the contribution of the stretched network. The damage model is designed to account for the progressive elimination of chains that are most highly loaded in the stretched network, so that the undamaged stiffness is restored when the strain rises above levels previously experienced. The proposed model reproduces the behavior of the Mullins effect in the MN system.

scholarly journals Highly stretchable, compressible, adhesive hydrogels with double network

2021 ◽  
Vol 28 (11) ◽  
Author(s):  
Cuiping Guo ◽  
Zhiwen Zeng ◽  
Shan Yu ◽  
Xiaoyan Zhou ◽  
Qunfeng Liu ◽  
...  
Keyword(s):  
Bovine Serum Albumin ◽  
Hydrogen Bonds ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Adhesive Properties ◽  
Double Network ◽  
High Fatigue ◽  
Highly Stretchable ◽  
Physical Interactions ◽  
Chain Entanglements

AbstractIn this work, a double network bovine serum albumin-polyacrylamide (BSA-PAM) adhesive hydrogel was fabricated, in which combination of physical interactions including hydrogen bonds and chain entanglements, and chemical covalent photo-crosslinking. The BSA-PAM hydrogel exhibited excellent mechanical and adhesive properties. The composite hydrogel not only demonstrated excellent tensile properties (maximum force elongation 1552%~2037%), but also displayed extremely high fatigue resistance even when subjected to compress strains of up to 85%. More importantly, the BSA-PAM hydrogel showed excellent adhesiveness to various substrates (90 kPa~150 kPa for glass and 9.74 kPa~35.09 kPa for pigskin). This work provided a facile way of fabricating tough, stretchable and adhesive BSA-PAM hydrogels.

scholarly journals Conjoined-network rendered stiff and tough hydrogels from biogenic molecules

2019 ◽  
Vol 5 (2) ◽  
pp. eaau3442 ◽  
Author(s):  
Liju Xu ◽  
Chen Wang ◽  
Yang Cui ◽  
Ailing Li ◽  
Yan Qiao ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Compressive Modulus ◽  
Cross Linking ◽  
General Strategy ◽  
Soft Or ◽  
Double Network ◽  
Dissipation Mechanism ◽  
New Strategy ◽  
Biological Sources ◽  
Network Approaches

Hydrogels from biological sources are expected as potential structural biomaterials, but most of them are either soft or fragile. Here, a new strategy was developed to construct hydrogels that were both stiff and tough via the formation of the conjoined-network, which was distinct from improving homogeneity or incorporating energy dissipation mechanisms (double-network) approaches. Conjoined-network hydrogels stand for a class of hydrogels consisting of two or more networks that are connected by sharing interconnection points to collaborate and featured as follows: (i) All the composed networks had a similar or equal energy dissipation mechanism, and (ii) these networks were intertwined to effectively distribute stress in the whole system. As a specific example, a biogenic conjoined-network hydrogel was prepared by electrostatically cross-linking the chitosan-gelatin composite with multivalent sodium phytate. The combination of high compressive modulus and toughness was realized at the same time in the chitosan-gelatin-phytate system. Moreover, these physical hydrogels exhibited extraordinary self-recovery and fatigue resistance ability. Our results provide a general strategy for the design of biocompatible stiff and tough conjoined-network hydrogels due to a variety of potential cross-linking mechanisms available (e.g., electrostatic attraction, host-guest interaction, and hydrogen bonding).

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