Interdiffusion and Self-Cross-Linking in Acetal-Functionalized Latex Films

2004 ◽  
Vol 37 (16) ◽  
pp. 6141-6152 ◽  
Author(s):  
Florence Mazuel ◽  
Chuong Bui ◽  
Bernadette Charleux ◽  
Eva Cabet-Deliry ◽  
Mitchell A. Winnik
Keyword(s):  
Cross Linking ◽  
Latex Films

Rheology of latex films bonded to wood: influence of cross-linking

Holzforschung ◽  
2006 ◽  
Vol 60 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Francisco López-Suevos ◽  
Charles E. Frazier
Keyword(s):  
Phenol Formaldehyde ◽  
Adhesive Layer ◽  
Wood Adhesive ◽  
Water Soluble ◽  
Cross Linking ◽  
Sample Type ◽  
Master Curves ◽  
Latex Films ◽  
Adhesive Interaction ◽  
Tan Δ

Abstract Parallel-plate rheological analysis was conducted on two types of cross-linking poly(vinyl acetate) latex films: dry freestanding films, and dry films bonded directly to wood (composites). For each sample type, three levels of cross-linking were used: (1) little or no cross-linking of unaltered latex; (2) substantial cross-linking through AlCl3 catalysis of N-methylolacrylamide co-monomer; and (3) greater cross-linking from a phenol-formaldehyde resol additive, in addition to AlCl3 catalysis. Simple thermal scans revealed a strong wood/adhesive interaction; wood increased the base polymer T g by ∼5°C in all adhesives. Relative to the simple thermal scans, time-temperature master curves provided more insight and information about the wood/adhesive interaction. Storage modulus and tan δ master curves both indicated that wood retarded adhesive cross-linking. Using time-temperature superposition, a segmental coupling analysis demonstrated that wood actually narrowed the breadth of the glass transition, or reduced segmental coupling. Cross-linking influenced segmental coupling, but in a fashion that was dependent on the presence or absence of wood. Wood-induced reductions in cross-linking and in segmental coupling were attributed to the diffusion of water-soluble reactive compounds away from the adhesive layer and into the bulk wood. Time/temperature equivalence provides a sensitive means to detect interactions between wood and viscoelastic adhesives.

Polymer Interdiffusion vs Cross-Linking in Carboxylic Acid−Carbodiimide Latex Films

1999 ◽  
Vol 32 (22) ◽  
pp. 7692-7695 ◽  
Author(s):  
Hung H. Pham ◽  
Mitchell A. Winnik
Keyword(s):  
Carboxylic Acid ◽  
Cross Linking ◽  
Latex Films ◽  
Polymer Interdiffusion

Influence of intraparticle cross-linking on polymer diffusion in latex films prepared from secondary dispersions

2022 ◽  
Vol 164 ◽  
pp. 106691
Author(s):  
Yang Liu ◽  
Kenneth Tran ◽  
Kevin Ho ◽  
Jessica Emsermann ◽  
Margaret Zhang ◽  
...  
Keyword(s):  
Cross Linking ◽  
Polymer Diffusion ◽  
Latex Films

Mechanism of Formation of Cream in GR-S Latex

1955 ◽  
Vol 28 (2) ◽  
pp. 641-656
Author(s):  
L. H. Howland ◽  
Alfred Nisonoff
Keyword(s):  
Water Level ◽  
The Other ◽  
Cross Linking ◽  
High Solids ◽  
Mechanism Of Formation ◽  
Latex Films ◽  
Ferrous Sulfide ◽  
Other Hand ◽  
Large Particles ◽  
Number Of Particles

Abstract The formation of cream, which occurred in many of the early cold, high-solids GR-S latexes, is undesirable because it results in nonuniformity of the latex and is injurious to the properties of latex films. On the other hand, it is dispersible and, hence, much more tolerable than coagulum. The mechanism of its formation is, therefore, of interest. A cold high-solids latex activated by ferrous sulfide was used as the basis for the study. The giant particles constituting cream begin forming between 18 and 35 per cent conversion in latex stabilized only with the soap present initially, and increase in quantity until the end of polymerization. Their formation can be prevented by the timely addition of sufficient stabilizing soap, or by the use of a soap which initiates a small enough number of particles in relation to its stabilizing capacity. The formation of coagulum, rather than large particles, is favored by decreasing the amount of electrolyte or increasing the amount of water charged, and by the presence of cross-linking in the polymer. The effect of increasing the water level or introducing cross-linking is to increase the size rather than the amount of agglomerates. Methods are suggested for controlling the formation of very large particles.

Effect of Cross-Linking on Polymer Diffusion in Poly(butyl methacrylate-co-butyl acrylate) Latex Films

1999 ◽  
Vol 32 (19) ◽  
pp. 6102-6110 ◽  
Author(s):  
Toshiyuki Tamai ◽  
Patrick Pinenq ◽  
Mitchell A. Winnik
Keyword(s):  
Butyl Acrylate ◽  
Butyl Methacrylate ◽  
Cross Linking ◽  
Polymer Diffusion ◽  
Latex Films ◽  
Acrylate Latex

Acetal Functionalized Latex Films Capable of Cross-Linking at Ambient Temperatures

2001 ◽  
pp. 157-171 ◽  
Author(s):  
C. Soares ◽  
B. Charleux ◽  
J.-P. Vairon ◽  
C. Vergé ◽  
K. Loyen
Keyword(s):  
Cross Linking ◽  
Latex Films ◽  
Ambient Temperatures

PREVULCANIZATION OF NATURAL RUBBER LATEX BY UV TECHNIQUES: A PROCESS TOWARDS REDUCING TYPE IV CHEMICAL SENSITIVITY OF LATEX ARTICLES

2010 ◽  
Vol 83 (2) ◽  
pp. 133-148 ◽  
Author(s):  
S. Schlögl ◽  
A. Temel ◽  
R. Schaller ◽  
A. Holzner ◽  
W. Kern
Keyword(s):  
Natural Rubber ◽  
Addition Reaction ◽  
Bond Cleavage ◽  
Natural Rubber Latex ◽  
Innovative Technology ◽  
Cross Linking ◽  
Latex Films ◽  
Photochemical Process ◽  
Sulfur Vulcanization ◽  
Ene Addition

Abstract The UV induced prevulcanization of natural rubber (NR) latex provides an innovative technology for an efficient cross-linking. In the photochemical process, a selected photoinitiator and a poly-functional thiol are added to the NR latex. Free radicals (bond cleavage of the photoinitiator) are generated due to UV irradiation and cross-linking of the latex particles is then achieved by a thiol-ene addition reaction. The thiol-ene addition reaction in NR films is characterized with Fourier transform infrared and Raman spectroscopy. To achieve the prevulcanization of latex, both a thin film photoreactor and a falling film photoreactor are applied. Solid latex films are then produced by conventional dipping of the precured NR latex. The NR latex films are distinguished by good skin compatibility due to the absence of sensitizing or irritating processing agents which are used in conventional sulfur vulcanization. Moreover UV cross-linked films display excellent physical properties as well as high aging stabilities. Further advantages of the new technology compared to conventional sulfur vulcanization are low energy consumption together with short vulcanization times.

Parallel-plate rheology of latex films bonded to wood

Holzforschung ◽  
2005 ◽  
Vol 59 (4) ◽  
pp. 435-440 ◽  
Author(s):  
Francisco López-Suevos ◽  
Charles E. Frazier
Keyword(s):  
Glass Transition ◽  
Vinyl Acetate ◽  
Parallel Plate ◽  
Mechanical Response ◽  
Relaxation Times ◽  
Water Soluble ◽  
Cross Linking ◽  
Damping Factor ◽  
Latex Films ◽  
Neat Films

Abstract A parallel-plate rheological analysis was developed for two types of cross-linking poly(vinyl acetate) latex films: solid freestanding films (neat), and solid films bonded directly to wood substrates (composites). The composite sample glass transition was increased by 5°C relative to the neat films, suggesting a strong interaction through polymer adsorption. Time-temperature equivalence was used to evaluate the mechanical response and the distribution of relaxation times in both systems. The resulting master curves revealed significant differences in the mechanical response during the glass transition: the neat films exhibited a 2.5–3-decade change in storage modulus and a damping factor of 1.65, while the composite samples showed a much smaller transition (approx. 0.3 decades and tan δ=0.4, respectively). The coupling model of Plazek and Ngai adequately described segmental relaxations in the glass transition. It was found that wood caused a small but significant decrease in segmental coupling (n=0.32±0.01) relative to that of the neat PVAc films (n=0.37±0.01). This finding was independently confirmed by directly fitting the Gram-Charlier statistical model to evaluate the distribution breadth. That wood caused an increase in the poly(vinyl acetate) glass transition, but a decrease in the related segmental coupling seems counterintuitive. The decrease in segmental coupling may result from reduced cross-linking in the composite films relative to the neat films; perhaps wood absorbs water-soluble reactive chains that would otherwise increase cross-linking in the neat films.

Influence of Calcium Ions on the Plant Cell Surface: Membrane Fusions and Conformational Changes

1974 ◽  
Vol 32 ◽  
pp. 154-155
Author(s):  
D. James Morré ◽  
Charles E. Bracker ◽  
William J. VanDerWoude
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Conformational Changes ◽  
Calcium Ions ◽  
Surface Membrane ◽  
Carboxyl Groups ◽  
Cross Linking ◽  
Ultrastructural Evidence ◽  
Glycine Max L ◽  
Wall Extensibility

Calcium ions in the concentration range 5-100 mM inhibit auxin-induced cell elongation and wall extensibility of plant stems. Inhibition of wall extensibility requires that the tissue be living; growth inhibition cannot be explained on the basis of cross-linking of carboxyl groups of cell wall uronides by calcium ions. In this study, ultrastructural evidence was sought for an interaction of calcium ions with some component other than the wall at the cell surface of soybean (Glycine max (L.) Merr.) hypocotyls.

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