scholarly journals Rheology of nitrile rubber with hybrid crosslinked network composed of covalent bonding and hydrogen bonding

RSC Advances ◽  
2017 ◽  
Vol 7 (26) ◽  
pp. 15978-15985 ◽  
Author(s):  
Yonggang Shangguan ◽  
Jie Yang ◽  
Qiang Zheng
Keyword(s):  
Hydrogen Bonding ◽  
Covalent Bonding ◽  
Nitrile Rubber ◽  
Dicumyl Peroxide ◽  
Crosslinking Agents

A hybrid crosslinked network composed of covalent bonding and non-covalent bonding was constructed in nitrile rubber (NBR) by using a compound crosslinking agents dicumyl peroxide (DCP) and N,N-methylenebis acrylamide (MBA).

Structure and hydrogen bonding inCaSiD1+x: Issues about covalent bonding

2006 ◽  
Vol 74 (22) ◽  
Author(s):  
H. Wu ◽  
W. Zhou ◽  
T. J. Udovic ◽  
J. J. Rush ◽  
T. Yildirim
Keyword(s):  
Hydrogen Bonding ◽  
Covalent Bonding

scholarly journals Tannic Acid as a Natural Crosslinker for Catalyst-Free Silicone Elastomers From Hydrogen Bonding to Covalent Bonding

2021 ◽  
Vol 9 ◽  
Author(s):  
Sen Kong ◽  
Rui Wang ◽  
Shengyu Feng ◽  
Dengxu Wang
Keyword(s):  
Hydrogen Bonding ◽  
Tannic Acid ◽  
Room Temperature ◽  
Covalent Bonding ◽  
Processing Technique ◽  
Hydrophobic Property ◽  
Silicone Elastomers ◽  
Good Thermal Stability ◽  
Catalyst Free ◽  
Base Polymer

The construction of silicone elastomers crosslinked by a natural crosslinker under a catalyst-free method is highly desirable. Herein we present catalyst-free silicone elastomers (SEs) by simply introducing tannic acid (TA) as a natural crosslinker when using poly (aminopropylmethylsiloxane-co-dimethylsiloxane) (PAPMS) as the base polymer. The crosslinked bonding of these SEs can be easily changed from hydrogen bonding to covalent bonding by altering the curing reaction from room temperature to heating condition. The formability and mechanical properties of the SEs can be tuned by altering various factors, including processing technique, the amount of TA and aminopropyl-terminated polydimethylsiloxane, the molecular weight and -NH2 content of PAPMS, and the amount of reinforcing filler. The hydrogen bonding was proved by the reversible crosslinking of the elastomers, which can be gradually dissolved in tetrahydrofuran and re-formed after removing the solvent. The covalent bonding was proved by a model reaction of catechol and n-decylamine and occurred through a combination of hydroxylamine reaction and Michael addition reaction. These elastomers exhibit good thermal stability and excellent hydrophobic property and can bond iron sheets to hold the weight of 500 g, indicating their promising as adhesives. These results reveal that TA as a natural product is a suitable “green” crosslinker for the construction of catalyst-free silicone elastomers by a simple crosslinking strategy. Under this strategy, TA and more natural polyphenols could be certainly utilized as crosslinkers to fabricate more organic elastomers by selecting amine-containing polymers and further explore their extensive applications in adhesives, sealants, insulators, sensors, and so forth.

Dynamically Vulcanized PP/EPDM Blends: Multifunctional Peroxides as Crosslinking Agents — Part I

2004 ◽  
Vol 77 (5) ◽  
pp. 955-971 ◽  
Author(s):  
Kinsuk Naskar ◽  
Jacques W. M. Noordermeer
Keyword(s):  
Single Molecule ◽  
Good Alternative ◽  
Thermoplastic Elastomers ◽  
Dicumyl Peroxide ◽  
Thermoplastic Polymer ◽  
Decomposition Products ◽  
Blooming Effect ◽  
Thermoplastic Vulcanizates ◽  
By Products ◽  
Crosslinking Agents

Abstract Thermoplastic vulcanizates (TPVs) or dynamic vulcanizates are a special class of thermoplastic elastomers, produced by mixing and crosslinking of a rubber and a thermoplastic polymer simultaneously. In a previous study, it was demonstrated that the use of dicumyl peroxide in combination with triallyl cyanurate as crosslinking agents provides a good overall balance of physical properties of PP/EPDM TPVs. Commonly used peroxides like dicumyl peroxide generally produce volatile decomposition products, which sometimes provide a typical smell or show a blooming effect. In this paper multifunctional peroxides are described, which reduce the above-mentioned problems. They consist of a peroxide and co-agent-functionality combined in a single molecule. The multifunctional peroxides provide properties of TPVs, which are comparable with commonly employed co-agent assisted peroxides. The solubility and kinetic aspects of the various peroxides are highlighted, as well as the decomposition products of the multifunctional peroxides with respect to the avoidance of smelly by-products. Particularly, 2,4-diallyoxy-6-tert-butylperoxy-1,3,5-triazine turns out to be a very good alternative to the dicumyl peroxide/triallyl cyanurate combination.

Preparation and evaluation of PAMAM dendrimer-based polymer gels physically cross-linked by hydrogen bonding

2019 ◽  
Vol 7 (9) ◽  
pp. 3918-3925 ◽  
Author(s):  
Hailin Cong ◽  
Liping Zhou ◽  
Qingye Meng ◽  
Yixin Zhang ◽  
Bing Yu ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Antibacterial Properties ◽  
Polymer Gels ◽  
Pamam Dendrimer ◽  
Covalent Bonding ◽  
Cross Linking ◽  
Anti Inflammatory ◽  
Preparation And Evaluation

Dendrimer-based polymer gels with good antibacterial properties and anti-inflammatory properties were prepared without any covalent bonding cross-linking agents.

scholarly journals Borax assisted synthesis of dialdehyde Carboxymethyl cellulose-Dextrin/Gelatin based biocompatible self-healing hydrogel

2021 ◽  
Author(s):  
Amit Kumar Sharma ◽  
Priya Bhalla ◽  
Balbir Singh Kaith ◽  
Bhagya Shree ◽  
Simran Sehgal ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Carboxymethyl Cellulose ◽  
Covalent Bonding ◽  
The Self ◽  
Self Healing ◽  
Binding Agent ◽  
Lower Viscosity ◽  
Potential Applications ◽  
Biomedical Field ◽  
Cross Linker

Abstract The hydrogels with self-healing properties have high potential applications in the biomedical field. Generally, the imine bonds are used as the dynamic covalent bonding in the self-healing hydrogels and hydrogen bonding is used for providing additional strength to self-healing hydrogels. In the presented work, Gelatin, dialdehyde dextrin, and dialdehyde Carboxymethyl cellulose (CMC) based hydrogels were prepared which are biocompatible and biodegradable and hence, can be used in biomedical field. Borax and glutaraldehyde were used as binding agent and cross-linker, respectively. The dynamic imide bond formed between gelatin-dialdehyde dextrin, gelatin-dialdehyde CMC, and gelatin-glutaraldehyde were responsible for self-healing ability of the prepared hydrogel. The rheological studies were also carried out which showed that as a consequence of lower viscosity the hydrogels can show injectable properties. The sample was also found to be blood compatible, which further highlights its biomedical importance.

scholarly journals Elucidation of Charge Contribution in Iridium-Chelated Hydrogen-Bonding Systems

2021 ◽  
Vol 9 ◽  
Author(s):  
Barbora Balónová ◽  
Barry A. Blight
Keyword(s):  
Hydrogen Bonding ◽  
Covalent Bonding ◽  
Iridium Complexes ◽  
Supramolecular Systems ◽  
Bonding Systems

We present two iridium complexes 1H+ and 2H+ that contain cationic ligands to extend the knowledge of charge-assisted hydrogen bonding (CAHB), which counts among the strongest non-covalent bonding interactions. Upon protonation, both complexes were converted into new hydrogen-bonding arrays with various selectivity for respective H-bonding partners. This study compares the association strengths of four hydrogen-bonding co-systems, emphasizing the roles of CAHB in supramolecular systems. We determined that the cationic charge in these systems contributed up to 2.7 kJ mol−1 in the H-bonding complexation processes.

scholarly journals PROPERTIES OF DYNAMIC THERMOPLASTIC ELASTOMERS BASED ON POLYPROPYLENE AND BUTADIEN-NITRIL RUBBER

2019 ◽  
Vol 62 (7) ◽  
pp. 107-117
Author(s):  
Najaf T. Kakhramanov ◽  
Ulviya M. Mammadli ◽  
Nushaba B. Arzumanova ◽  
Zulfira N. Huseynova ◽  
Esmira V. Dadasheva ◽  
...  
Keyword(s):  
Melt Flow Index ◽  
Thermoplastic Elastomers ◽  
Nitrile Rubber ◽  
Polymer Composition ◽  
Flow Index ◽  
Dicumyl Peroxide ◽  
Elastic State ◽  
Melt Flow ◽  
Deformation Properties ◽  
Butadiene Nitrile Rubber

The study results of the influence of butadiene-nitrile rubber different grades concentration, cross-linking agent type and content on the physico-mechanical and thermo-deformation properties of polymer compositions based on polypropylene are presented. Mixing of the components was carried out on hot rollers in the melt mode at 170 °C. A preliminary study of rubber concentration affect on the properties of compositions based on polypropylene showed that the introduction of an elastomeric component leads to a regular decrease in the strength and elongation at break of the compositions. The results of investigation of the thermo-deformation properties of polymer compositions showed that at a rubber concentration of 30wt%, and higher on thermomechanical curves, the region of the high-elastic state characteristic of rubbers is noticeably distinguished. Taking into account that the rubber materials are obtained during the process of their vulcanization, it seemed interesting to crosslink materials with two types of vulcanizing agents – dicumyl peroxide and sulphur for obtaining comparable results. The concentration of dicumyl peroxide was varied between 0.5 - 2.0 wt%. It was found that the use of dicumyl peroxide in an amount of 1.0-2.0 wt% is accompanied by intense occurrence of crosslinking with the formation of an irreversible highly crosslinked structure in the polymer composition. Based on the evaluation of the melt flow index of the vulcanized compositions, it was found that at the concentration of dicumyl peroxide in an amount of 0.5 wt% they still retain the ability to flow. At concentrations above 0.5 wt% of dicumyl peroxide the polymer compositions completely lose the fluidity of the melt. It was found that with an increase in the sulphur concentration from 3.0 to 10 wt% the decrease in the melt flow index from 2.76 to 0.616 g/10 min is observed. It was found that the crosslinking process predominantly proceeds through double bonds of butadiene-nitrile rubber, thereby facilitating the production of dynamically vulcanized polymer materials with a unique combination of structure and properties. This was confirmed by the results of a study of the thermo-deformation characteristics of compositions, according to which a transition from the region of a high-elastic state to viscous-flow state is observed in all samples subjected to sulfur vulcanization. The results of the study make it possible to state that dynamic thermoplastic elastomers can be obtained only if the ratio of the components used in the polymer composition is correctly selected.

Hydrogen bonding in liquid methanol at ambient conditions and at high pressure

2000 ◽  
Vol 98 (3) ◽  
pp. 125-134 ◽  
Author(s):  
T. Weitkamp, J. Neuefeind, H. E. Fisch
Keyword(s):  
High Pressure ◽  
Hydrogen Bonding ◽  
Ambient Conditions
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