Reaction Mechanisms, Structure, and Properties of Methylol Compounds in Cross-Linking Cotton1

1968 ◽  
Vol 38 (2) ◽  
pp. 156-176 ◽  
Author(s):  
H. Petersen
Keyword(s):  
Reaction Mechanisms ◽  
Cross Linking ◽  
Structure And Properties

Influence of cross-linking density on the structure and properties of the interphase within supported ultrathin epoxy films

2016 ◽  
Vol 51 (19) ◽  
pp. 9019-9030 ◽  
Author(s):  
Kai Li ◽  
Yan Li ◽  
Qingsong Lian ◽  
Jue Cheng ◽  
Junying Zhang
Keyword(s):  
Cross Linking ◽  
Structure And Properties

scholarly journals MODIFICATION OF MIXTURES BASED ON ETHYLENEPROPYLENE RUBBER AND SILICON ACID FILLER

2021 ◽  
Vol 64 (2) ◽  
pp. 81-86
Author(s):  
Olga Yu. Solovyeva ◽  
Andrey B. Vetoshkin ◽  
Sergey V. Gudkov ◽  
Elena L. Nikitina
Keyword(s):  
Strength Properties ◽  
Rubber Matrix ◽  
Cross Linking ◽  
Structure And Properties ◽  
Component Mixture ◽  
Static Test ◽  
Silica Filler ◽  
Bound Rubber ◽  
Silica Fillers ◽  
Filler Distribution

The aim of the work was to study the effect of bis-(triethoxysilylpropyl)-tetrasulfide (TESPT) mixed with carbon black N330 in a ratio of 1:1, as a technical product OFS 6945 on the structure and properties of rubber mixtures and rubbers based on ethylene propylene rubber of the brand Vistalon 2504N and silica filler (KKN) of the brand Rosil-175, taken at a dosage of 30 wt. h. per 100 wt.h. rubber. The content of TESPT was 0.035, 0.050 and 0.070 mmol / 100 g of rubber. A group of vulcanizing agents included sulphur, thiuram, captax, zinc oxide and technical stearin. Rubber mixtures were prepared on rollers Lb 320 160/160. Organosilane was injected into rubber at the same time as Rosil-175. The homogeneity of the filler distribution in the finished mixtures was evaluated based on the results of testing samples on the RPA-2000 vibrorheometer. Vulcanization characteristics were determined using an MDR-2000 device. The structure of mixtures and rubbers was studied by the method of equal swelling of samples in toluene. It is shown that with the increasing content of TESPT, the proportion of bound rubber in a three-component mixture of the rubber – filler – organosilane increases due to the formation of interfacial connections. The uniformity of distribution of silica fillers in rubber matrix also increases. Workability of the mixtures on roller equipment improves. The rate of cross-linking in the core period and the degree of cross-linking of macromolecules at the same time curing increase as well. As a result, the elastic-strength properties of rubbers determined in the static test mode are improved, the best complex of which is provided with an organosilane content of 0.050 mmol/100 g of rubber.

Oxidative polymerisation of models for phenolic lignin end-groups by laccase

Holzforschung ◽  
2010 ◽  
Vol 64 (1) ◽  
Author(s):  
Dimitri Areskogh ◽  
Jiebing Li ◽  
Paula Nousiainen ◽  
Göran Gellerstedt ◽  
Jussi Sipilä ◽  
...  
Keyword(s):  
Reaction Mechanisms ◽  
Biological Significance ◽  
Oxidation Potential ◽  
Cross Linking ◽  
Redox Enzyme ◽  
Covalent Bonds ◽  
Radical Coupling ◽  
End Groups ◽  
Product Profile ◽  
Temperature Optima

AbstractThe redox enzyme laccase can lead to cross-linking of lignin molecules by oxidising phenolic end groups to resonance-stabilised radicals that can undergo radical coupling to form covalent bonds. This property has potential for many technical applications. However, laccase treatment can also lead to degradation. Experiments were performed with two laccases of different oxidation potential and pH and temperature optima. The predominant reaction following laccase oxidation is the formation of 5-5′ and 4-O-5′ bonds. If the 5-position is blocked, other reactions occur, including coupling of the 1-position and oxidation of the α-position, which aggravates cross-linking of different lignin molecules. The product profile generated by the two laccases is somewhat different, mainly because of the different pH rather than differences in enzyme activity. Reaction mechanisms and the technical and biological significance of the results are discussed.

Structure and properties of hybrid biopolymer particles fabricated by co-precipitation cross-linking dissolution procedure

2018 ◽  
Vol 514 ◽  
pp. 156-164 ◽  
Author(s):  
Yu Xiong ◽  
Radostina Georgieva ◽  
Axel Steffen ◽  
Kathrin Smuda ◽  
Hans Bäumler
Keyword(s):  
Cross Linking ◽  
Structure And Properties ◽  
Co Precipitation

Effect of Cross-Linking Methods on Structure and Properties of Poly(ε-caprolactone) Stabilized Hydrogels Containing Biopolymers

2012 ◽  
Vol 13 (8) ◽  
pp. 2263-2272 ◽  
Author(s):  
Geta David ◽  
Mariana Cristea ◽  
Ciprian Balhui ◽  
Daniel Timpu ◽  
Florica Doroftei ◽  
...  
Keyword(s):  
Cross Linking ◽  
Structure And Properties

Investigations of the effects of glyoxal cross-linking on the structure and properties of chitosan fiber

2005 ◽  
Vol 61 (4) ◽  
pp. 393-398 ◽  
Author(s):  
Qing Yang ◽  
Fengdong Dou ◽  
Borun Liang ◽  
Qing Shen
Keyword(s):  
Cross Linking ◽  
Structure And Properties ◽  
Chitosan Fiber

Effects of Cross-Linking and Branching on the Molecular Constitution of Diene Polymers

1948 ◽  
Vol 21 (2) ◽  
pp. 461-470
Author(s):  
Paul J. Flory
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Reaction Mechanisms ◽  
Structural Unit ◽  
Random Distribution ◽  
Average Chain Length ◽  
Cross Linking ◽  
Gel Formation ◽  
Molecular Constitution ◽  
Kinetic Treatment

Abstract Reaction mechanisms whereby cross-linked and branched polymer structures may be formed during the polymerization of dienes are discussed. A kinetic treatment of the formation of cross-linkages via the occasional addition of a free radical to the unsaturated carbon of a structural unit of a previously polymerized molecule is presented. It is pointed out that the rate of this addition step relative to monomer addition can be deduced from the average chain length and the conversion at which gelation occurs. Cross-linkages introduced by the mechanism under consideration are not distributed at random, but the deviations from a random distribution are unimportant except at high conversions. Conditions are examined under which the cross-linking reaction decreases the total number of molecules more rapidly than they are formed. Physical properties of polymers (with particular emphasis on vulcanized rubbers) are most conveniently interpreted in terms of (1) the primary molecular weight (i.e., molecular weight in the absence of cross-linkages) and its distribution, and (2) the concentration of cross-linkages. The actual molecular-weight distribution, which may be severely distorted by the presence of cross-linkages, is inappropriate for direct correlation with the more important physical properties. The modifiers or regulators commonly employed in diene polymerizations suppress gel formation by reducing the primary molecular weight; they do not actually reduce cross-linking. This reduction in molecular weight is not without other undesired consequences, however.

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