Modern Transparent Papers: Materials, Degradation, and the Effects of Some Conservation Treatments

1992 ◽  
Vol 267 ◽  
Author(s):  
Dianne Van Der Reyden ◽  
Christa Hofmann ◽  
Mary Baker ◽  
Marion Mecklenburg
Keyword(s):  
Physical Properties ◽  
Organic Solvents ◽  
Materials Characterization ◽  
Research Projects ◽  
Specific Chemical ◽  
Effects Of Aging ◽  
Composition Properties

ABSTRACTModern transparent papers, also known as tracing papers, require specific chemical and physical properties, such as translucency, smoothness, and whiteness, which are produced by specially formulated compositions and manufacturing procedures. Ironically, these special formulations may in some ways render such papers susceptible to problems from damage and degradation, while also making them particularly reactive to moisture and solvents that must be used in conservation treatments to correct these problems. In order to evaluate the effects of water and organic solvents on such papers, four research projects were designed to consider the variables of paper composition, properties, type of solvent, technique of application of solvent, and flattening. This paper summarizes findings on materials characterization, degradative effects of aging, and some effects of solvents used on transparent papers for stain reduction, humidification, and flattening.

EPDM Elastomers in Rubber Modified Plastics

1971 ◽  
Vol 44 (4) ◽  
pp. 1130-1146 ◽  
Author(s):  
C. L. Meredith
Keyword(s):  
Physical Properties ◽  
Elevated Temperatures ◽  
Rubber Particle ◽  
Accelerated Aging ◽  
Critical Parameters ◽  
Processing Conditions ◽  
Aging Property ◽  
Styrene Acrylonitrile ◽  
Plastic Matrix ◽  
Effects Of Aging

Abstract The superior resistance of EPDM to thermal and ultraviolet degradation makes the use of this elastomer particularly attractive in rubber modified plastics. Because of difficulty in grafting onto EPDM compared to polybutadiene or SBR, conventional emulsion polymerization processes do not give products with the desired balance of physical properties. In order to obtain the necessary degree of grafting and desired rubber particle size in the plastic matrix, a solution-precipitation polymerization was developed. This process is particularly well adapted for the preparation of EPDM modified styrene-acrylonitrile. Properties are quite dependent upon the EPDM composition used to modify the plastic. The amount and choice of third monomer are the most critical parameters with 5 to 12 C = C/1000 of 5-ethylidene-2-norbornene giving the best balance of properties. Relatively poor plastics result with dicyclopentadiene or 1, 4-hexadiene EPDM. while the physical properties of the EPDM-SAN plastic compare very favorably with commercial ABS, the chief advantage is a much greater resistance to the deleterious effects of aging. This is shown by comparative tests of oxygen uptake, accelerated aging, property retention and discoloration at elevated temperatures and during outside exposure, and rheological stability under severe processing conditions.

Strong Hydrogen Bonds Are Not Shielded in Ionic Liquids

2019 ◽  
Author(s):  
Teresa Naranjo ◽  
Rubén Álvarez-Asencio ◽  
Patricia Pedraz ◽  
Belén Nieto-Ortega ◽  
Enrique Burzurí ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Melting Point ◽  
Hydrogen Bonds ◽  
Physical Properties ◽  
Organic Solvents ◽  
Electrostatic Interactions ◽  
Room Temperature ◽  
Noncovalent Interactions ◽  
Binding Constants ◽  
Information Storage

Hydrogen bonds are arguably the most important of noncovalent interactions. The physical properties of water and the information storage in DNA depend on H-bonding, for instance. To this day, the balance between the Coulombic and covalent contributions to H-bonds is still under debate. Here, we show that H-bonded host-guest systems associate in ionic liquids, pure salts with melting point below room temperature, in which dipole-dipole electrostatic interactions should be negligible in comparison with dipole-charge interactions. Binding constants (<i>K</i><sub>a</sub>) obtained from titrations of four H-bonded host-guest systems in two organic solvents and two ionic liquids yield smaller yet comparable <i>K</i><sub>a</sub>values in ionic liquids than in organic solvents. We also detect the association event using force spectroscopy. Our results indicate that strong H-bonds are only moderately affected by surroundings composed entirely of charges, suggesting that the balance of Coulombic to covalent forces is not tipped towards the former.

Strong Hydrogen Bonds Are Not Shielded in Ionic Liquids

2019 ◽  
Author(s):  
Teresa Naranjo ◽  
Rubén Álvarez-Asencio ◽  
Patricia Pedraz ◽  
Belén Nieto-Ortega ◽  
Enrique Burzurí ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Melting Point ◽  
Hydrogen Bonds ◽  
Physical Properties ◽  
Organic Solvents ◽  
Electrostatic Interactions ◽  
Room Temperature ◽  
Noncovalent Interactions ◽  
Binding Constants ◽  
Information Storage

Hydrogen bonds are arguably the most important of noncovalent interactions. The physical properties of water and the information storage in DNA depend on H-bonding, for instance. To this day, the balance between the Coulombic and covalent contributions to H-bonds is still under debate. Here, we show that H-bonded host-guest systems associate in ionic liquids, pure salts with melting point below room temperature, in which dipole-dipole electrostatic interactions should be negligible in comparison with dipole-charge interactions. Binding constants (<i>K</i><sub>a</sub>) obtained from titrations of four H-bonded host-guest systems in two organic solvents and two ionic liquids yield smaller yet comparable <i>K</i><sub>a</sub>values in ionic liquids than in organic solvents. We also detect the association event using force spectroscopy. Our results indicate that strong H-bonds are only moderately affected by surroundings composed entirely of charges, suggesting that the balance of Coulombic to covalent forces is not tipped towards the former.

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