Solvent Resistance of Silicone Elastomers: Solvent-Polymer Interactions

1964 ◽  
Vol 37 (1) ◽  
pp. 261-267 ◽  
Author(s):  
K. B. Yerrick ◽  
H. N. Beck
Keyword(s):  
Block Copolymer ◽  
Aromatic Hydrocarbons ◽  
Dipole Interaction ◽  
Solubility Parameters ◽  
Silicone Elastomers ◽  
Polymer Interactions ◽  
Copolymer Structure ◽  
Aliphatic And Aromatic Hydrocarbons ◽  
The Individual ◽  
Parameter Values

Abstract The solubility parameters, δp, of a number of polymers have been determined by swelling in a series of solvents with various solubility parameter values, δ0. The δp values were obtained for (see PDF for diagram) During the course of this work it was concluded that solvent nature (polarity and association) play an important role in the swelling power of a solvent. These interactions create considerable ambiguity of the data in cases where dipole interaction or association takes place between polymer-solvent pairs or solvent-solvent pairs. For this reason a series of “select” solvents were chosen that did not display these interactions. Included in these “select” solvents were the aliphatic and aromatic hydrocarbons (δ0=6.0–9.2). In addition the aliphatic alcohols which are strongly hydrogen bonded were included to cover the upper range of δ0 values (δ0=10.8–14.2). This study has revealed that the swelling curves of siloxane copolymers yield only the individual δp values of the homopolymers. From these results it appears as though this type of measurement is not sensitive to copolymer structure, i.e., random or block copolymer structure.

The effect of RAFT-derived cationic block copolymer structure on gene silencing efficiency

Biomaterials ◽  
2012 ◽  
Vol 33 (30) ◽  
pp. 7631-7642 ◽  
Author(s):  
Tracey M. Hinton ◽  
Carlos Guerrero-Sanchez ◽  
Janease E. Graham ◽  
Tam Le ◽  
Benjamin W. Muir ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Gene Silencing ◽  
Copolymer Structure

scholarly journals The Composition of Cigarette Smoke. An Historical Perspective of Several Polycyclic Aromatic Hydrocarbons

2009 ◽  
Vol 23 (6) ◽  
pp. 384-410 ◽  
Author(s):  
A Rodgman ◽  
LC Cook
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Melting Point ◽  
Cigarette Smoke ◽  
Aromatic Hydrocarbons ◽  
Tobacco Smoke ◽  
Individual Component ◽  
Complex Mixtures ◽  
Polycyclic Aromatic ◽  
The Individual ◽  
Cigarette Mainstream Smoke

AbstractBecause of the significant advancements in fractionation, analytical, and characterization technologies since the early 1960s, hundreds of components of complex mixtures have been accurately characterized without the necessity of actually isolating the individual component. This has been particularly true in the case of the complex mixtures tobacco and tobacco smoke. Herein, an historical account of a mid-1950 situation concerning polycyclic aromatic hydrocarbons (PAHs) in cigarette smoke is presented. While the number of PAHs identified in tobacco smoke has escalated from the initial PAH, azulene, identified in 1947 to almost 100 PAHs identified by late 1963 to more than 500 PAHs identified by the late 1970s, the number of PAHs isolated individually and characterized by several of the so-called classical chemical means (melting point, mixture melting point, derivative preparation and properties) in the mid-1950s and since is relatively few, 14 in all. They were among 44 PAHs identified in cigarette mainstream smoke and included the following PAHs ranging from bicyclic to pentacyclic: Acenaphthylene, 1,2-dihydroacenaphthylene, anthracene, benz[a]anthracene, benzo[a]pyrene, chrysene, dibenz[a, h]anthracene, fluoranthene, 9H-fluorene, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, phenanthrene, and pyrene. One of them, benzo[a]pyrene, was similarly characterized in another study in 1959 by Hoffmann.

Text and Discourse Linguistic Creativity of Children's English-Language Adventure Fiction

2021 ◽  
pp. 5-15
Author(s):  
Maria I. Kiose ◽  
◽  
Keyword(s):  
Vector Space ◽  
English Language ◽  
Total Sample ◽  
Word Formation ◽  
Statistics Analysis ◽  
Individual Parameter ◽  
Creativity Assessment ◽  
Adventure Fiction ◽  
The Individual ◽  
Parameter Values

The article explores the specificity of linguistic creativity in the discourse of children's English-language adventure fiction of the 1950s. The aim of the research is to develop the parametrization and vector-space method of discourse and text linguistic creativity assessment to evaluate the linguistic creativity potential of individual texts displaying similar discourse features. To serve as the research data three discourse fragments were selected, which represent three basic narrative types, Orientation, Complicating Actions, Evaluation and Resolution. To achieve the aim, the author applies the procedure of parametrization analysis followed by general and analytic statistics analysis and vector-space modelling. With the system of 52 parameters featuring linguistic creativity in phonology, word-formation, morphology, lexicology and phraseology, syntax, and graphics, the author manually annotates and processes the discourse fragments of similar size exemplifying three narrative types of adventure fiction literature, with the total sample size of 55,000 characters. General statistics analysis allowed revealing the absolute and relative parameter values in three discourse fragments and defining the relative parametric activity of single parameters and parameter levels. Analysis of variance helped define the correlation indices of parameter paired combinations, which resulted in detecting significant binary parameter groups . Individual parameter values and their binary groups served to construe the vector-space models of discourse and text linguistic creativity for the discourse narrative types under consideration. Thus, the author obtained an efficient instrument for discourse linguistic creativity evaluation and, furthermore, for assessing the potential of each individual text in terms of displaying stronger or weaker correlation with the vector coordinates of the discourse linguistic creativity vector-space model. With the frequency and variance analysis, the author disclosed two types of discourse linguistic creativity performance techniques, that is the individual parameter activation and the parameter synchronization. Both must be considered when the decision on linguistic creativity assessment in a concrete text is made. The resulting model shows that the parameter values of linguistic creativity in individual texts can manifest themselves in appearing both higher and lower than the reference parameter values of discourse creativity, which can contribute to disclosing new directions in creativity processing and understanding.

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