Adhesion of High Polymers. 3. Effects of the Size, Shape, and Polarity on Adhesion to Cellophane

1958 ◽  
Vol 31 (4) ◽  
pp. 712-718
Author(s):  
S. S. Voyutskiĭ ◽  
A. I. Shapovalova ◽  
A. P. Pisarenko
Keyword(s):  
Molecular Weight ◽  
Bond Strength ◽  
Diffusion Theory ◽  
Polymer Molecule ◽  
High Polymer ◽  
Short Side ◽  
Polymer Adhesion ◽  
Polar Groups ◽  
Cohesive Properties ◽  
High Polymers

Abstract 1. The method developed by the authors has been used to study the influence of size, form, and polarity of macromolecules on the adhesion of high polymers to cellophane. 2. Adhesion of high polymers to cellophane increases with decreasing molecular weight. However, for maximum bond strength, the cohesive properties of the polymer must also be taken into account. 3. Increase of the number of short side chains in the polymer molecule lowers its adhesion. 4. The adhesion of a polymer to cellophane decreases with increasing contents of polar groups in its macromolecules. 5. The results are explained on the basis of the diffusion theory of high polymer adhesion developed by the authors.

Effect of Molecular Weight, Shape of the Molecule, and Presence of Polar Groups on the Autohesion of High Polymers. III

1957 ◽  
Vol 30 (2) ◽  
pp. 548-554 ◽  
Author(s):  
S. S. Voyutskiĭ ◽  
B. V. Shtarkh
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Temperature Dependence ◽  
Structural Changes ◽  
Chain Molecule ◽  
Complete Disappearance ◽  
Short Side ◽  
Polar Groups ◽  
Kinetics Of ◽  
High Polymers

Abstract 1. It is shown for polyisobutylenes of different molecular weight that increase in the size of the chain molecule retards autohesion, but increases the limiting value to which the work of autohesion tends with increasing contact time. 2. Investigation of the temperature dependence of autohesion of polyisobutylenes showed that the activation energy does not depend on the molecular weight of the polyisobutylene. 3. It is shown for polybutadienes with varying contents of 1,4- and 1,2-structures that autohesion decreases with increase in the number of short side groups in the molecule, which apparently hinder diffusion by purely steric causes. 4. Investigation of the temperature dependence of autohesion of butadienenitrile copolymers with different contents of acrylonitrile in the molecule showed that the activation energy of autohesion increases with increase of polar nitrile groups in the polymer. 5. It is shown for the vulcanization of natural rubber that the formation of a spatial structure results in complete disappearance of autohesion in high polymers. It is shown that the kinetics of changes of autohesion during vulcanization can effectively characterize the structural changes which take place in the polymer during the process.

Microscopic versus process parameters in heavy-oil upgrading

1992 ◽  
Vol 50 (1) ◽  
pp. 366-367
Author(s):  
V.A. Munoz ◽  
R.J. Mikula ◽  
C. Payette ◽  
W.W. Lam
Keyword(s):  
Molecular Weight ◽  
Liquid Fuels ◽  
Chemical Components ◽  
Heavy Oils ◽  
Synthetic Fuels ◽  
High Hydrogen ◽  
Optical Texture ◽  
Polar Groups ◽  
Anisotropic Character ◽  
Planar Molecules

The transformation of high molecular weight components present in heavy oils into useable liquid fuels requires their decomposition by means of a variety of processes. The low molecular weight species produced recombine under controlled conditions to generate synthetic fuels. However, an important fraction undergo further recombination into higher molecular weight components, leading to the formation of coke. The optical texture of the coke can be related to its originating components. Those with high sulfur and oxygen content tend to produce cokes with small optical texture or fine mosaic, whereas compounds with relatively high hydrogen content are likely to produce large optical texture or domains. In addition, the structure of the parent chemical components, planar or nonplanar, determines the isotropic or anisotropic character of the coke. Planar molecules have a tendency to align in an approximately parallel arrangement to initiate the formation of the nematic mesophase leading to the formation of anisotropic coke. Nonplanar highly alkylated compounds and/or those rich in polar groups form isotropic coke. The aliphatic branches produce steric hindrance to alignment, whereas the polar groups participate in cross-linking reactions.

scholarly journals Chitosan-Based Adhesive: Optimization of Tensile Shear Strength in Dry and Wet Conditions

2021 ◽  
Vol 2 (1) ◽  
pp. 110-120
Author(s):  
Maisa Abdelmoula ◽  
Hajer Ben Hlima ◽  
Frédéric Michalet ◽  
Gérard Bourduche ◽  
Jean-Yves Chavant ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Shear Strength ◽  
Bond Strength ◽  
Water Resistance ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Spread Rate ◽  
Assembly Time ◽  
Deacetylation Degree ◽  
Dry And Wet Conditions

Commercial adhesives present a high bond strength and water resistance, but they are considered non-healthier products. Chitosan can be considered as an interesting biosourced and biodegradable alternative, despite its low water resistance. Here, its wood bonding implementation and its tensile shear strength in dry and wet conditions were investigated depending on its structural characteristics. Firstly, the spread rate, open assembly time, drying pressure, drying temperature, and drying time have been determined for two chitosans of European pine double lap specimens. An adhesive solution spread rate of 1000 g·m−2, an open assembly time of 10 min, and a pressure temperature of 55 °C for 105 min led to a bond strength of 2.82 MPa. Secondly, a comparison between a high molecular weight/low deacetylation degree chitosan and a lower molecular weight/higher deacetylation degree chitosan was conducted. Tests were conducted with beech simple lap specimens in accordance with the implementation conditions and the conditioning treatments in wet and dry environments required for thermoplastic wood adhesive standards used in non-structural applications (EN 204 and EN 205). The results clearly revealed the dependence of adhesive properties and water resistance on the structural features of chitosans (molecular weight and deacetylation degree), explaining the heterogeneity of results published notably in this field.

The Change in the Raman Spectra of Chloroprene and Isoprene in the Polymerization Process

1943 ◽  
Vol 16 (4) ◽  
pp. 841-847
Author(s):  
A. Gantmacher ◽  
S. Medvedev
Keyword(s):  
Raman Spectrum ◽  
Double Bond ◽  
Raman Spectra ◽  
Polymer Molecule ◽  
Polymerization Process ◽  
High Polymer ◽  
Single Bond ◽  
Double Bonds ◽  
Continuous Background ◽  
Single Bonds

Abstract 1. When chloroprene and isoprene polymerize, besides the frequency characterizing the conjugate double bond in the monomer, there appears a higher frequency corresponding to the isolated double bond in the polymer. In the polymerization process, the intensity of the frequency of the conjugate double bond decreases and the intensity of the frequency of the isolated double bond increases. Because of the increase in the number of single bonds in the polymer, the intensity of the frequency of the single bond 1005 in the polymer is considerably greater than in the monomer. 2. Even in the case of the samples with high polymer contents (greater than 50 per cent), the intensity of the frequency of the conjugate double bond is considerably greater than the intensity of the frequency of the isolated double bond. This is attributable to the fact that part of double bonds disappear during polymerization. 3. The Raman spectra of the chloroprene and isoprene polymers differ essentially from those of the monomers. To characterize the frequencies of vibration in the polymer molecule, it is essential to investigate its Raman spectrum in a medium free of the monomer. 4. The formation of highly polymeric molecules on polymerization does not result in an increase in the intensity of the continuous background in spectrograms.

Bond Characteristics of Overlays Placed over Bridge Decks Sealed with High-Molecular-Weight Methacrylate

2000 ◽  
Vol 1697 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Bahram M. Shahrooz ◽  
Arnol J. Gillum ◽  
Jeremiah Cole ◽  
Ahmet Turer
Keyword(s):  
Molecular Weight ◽  
Bond Strength ◽  
High Molecular Weight ◽  
Fatigue Testing ◽  
Bridge Decks ◽  
Limit State ◽  
Surface Preparation ◽  
Service Level ◽  
Preparation Techniques ◽  
Bond Characteristics

The bond strength between portland cement overlays and bridge decks treated with high-molecular-weight methacrylate sealers is examined. The data universally suggest that sealers reduce the available bond strength. However, extra surface preparation techniques, such as light sandblasting of the sealed surface or broadcasting sand over the surface immediately after sealing [at approximately 1 kg/m2 (20 lb/100 ft2)], restore the strengths to 80 or 85 percent, respectively, of the unsealed surface. Service-level fatigue testing and loading well beyond the serviceability limit state do not adversely affect the bond strength so long as the sealed surface is treated before the application of the overlay. Therefore, to seal the existing cracks, bridge decks may be sealed if either of the recommended secondary surface preparation techniques is followed.

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