Physical Properties Of Films Research Articles

Dependence of Growth and Physical Properties of Films on the State of the Substrate

The paper includes a discussion of the types of surface structure observed on a selection of crystal materials and an account of the forms of atomic arrangement taken by deposit material on such surfaces. We are not yet in a position to predict the type of structure to be expected in a given case. The once-disputed subject of pseudomorphism is examined and recent evidence for the existence of this effect is considered. Finally an account is given of the various results obtained in studies of epitaxial growth through layers of amorphous material.

Some physical properties of films made from cellulose dissolved in solutions of nitrogen dioxide in dimethylformamide

Water-soluble films of cellulose nitrate-nitrite were prepared by dissolving bleached sulfite pulp in a solution of nitrogen dioxide in dimethylformamide (DMF) at room temperature and heating the solution at 70°C for about 3 hr. Their water sorption, fine structure, and electrical properties were measured and compared with those of three other films—one water soluble (poly(vinyl alcohol)) and two water insoluble (cellophane and a film prepared from a cellulose solution in the nitrogen dioxide–DMF mixture and cast immediately after the cellulose had dissolved at room temperature). A comparison between the properties of water-soluble films and the poly(vinyl alcohol) film showed that the former had higher crystallinity, lower moisture absorption in the 0–80% relative humidity region, lower permittivity and a.c. conductance, and higher d.c. resistance. The DMF-cast water-insoluble film adsorbed less moisture than the cellophane film.

Effect of Substrate Potential on Al2O3 Films Prepared by Electron Beam Evaporation

In previous experiments the authors explored the deposition of Al2O3 films on silicon by electron-beam evaporation. These films exhibited unstable offset voltages, measured by C–V techniques, and poor radiation resistance. This paper describes the continuation of this study, with the discovery that electrostatic charges developed on the substrates during the electron-beam deposition process play a significant role in affecting the electrical and physical film properties. These investigations indicate that the buildup of negative charge from stray electrons on insulating substrates apparently repels oxygen ions thus altering the stoichiometry of the final film. Control of this charge buildup alters both the electrical and optical properties of the Al2O3 films. Al2O3 films varying in shades of brown to completely clear are produced by altering the electrostatic fields from −22 V (for the darkest films) measured between substrate and ground to less than −2 V between substrate and ground (for the clearest films). Ultraviolet spectra, radiation results, and C–V data indicate that a significant amount of dissociation takes place from the evaporant source during the electron-beam deposition.

Effect of Stress on the Physical Properties of Thin Films

Residual stresses are almost always present in thin films; the magnitude of the stress (tensile or compressive) can be as small as 107 or as large as 1010 dyn/cm2. The stress in fine-grained polycrystalline films is generally isotropic in the plane of the film, and has no stress component perpendicular to the film plane. In such films there is then an isotropic strain in the film plane with a Poisson’s strain normal to the plane. For single crystal films the strain anisotropy will depend on the orientation of the film axes with respect to the substrate. In either case these strains induce an anisotropy and changes in the physical properties of the film. As examples of the effect of stress, the changes in magnetic and superconducting transition temperatures, and the induced magnetic, resistive, and optical anisotropies will be discussed.

A study of the morphology and physical properties of polypropylene films

AbstractData are presented showing that rapidly quenched polypropylene films contain a paracrystalline phase in addition to crystalline and amorphous phases. The density of the paracrystalline phase was found to vary between 0.8890 and 0.9080 g./cm.3. Other data show that the density of quenched polypropylene films increases during aging, the increase being a linear function of the logarithm of the film age. The physical properties of the films, secant modulus, impact strength, and coefficient of friction, were found to vary not only with crystallinity, i.e., composition‐dependent density, but also to vary during aging when the density was increasing with little change in crystallinity. An example of this dependence is the increase in secant modulus of 10.9 × 106 psi/g./cm.3 during aging and only 3.7 × 106 psi/g./cm.3 as the crystallinity increased. Because of the three phases and the density–time change, it is possible to have films with the same density and different physical properties and, conversely, films with the same physical properties and different densities.

Characteristics of experimental cis‐1,4‐polyisoprene latices

AbstractExperimental latices of synthetic cis‐1,4‐polyisoprene and films and cellular objects produced from them are described. The latices of the synthetic polymers with molecular weights of about 2,000,000 are stabilized by anionic surfactants and have weight median particle diameters of about 0.9 μ and log normal particle size distribution. Tensile properties and flow characteristics of unvulcanized latex films could be regulated by introduction of controlled, small, amounts of crosslinking into the latex. Procedures used for crosslink density determination on cis‐polyisoprene latex at various stages of use are described. Vulcanized latex films having maximum tensile strengths (5500–6000 p.s.i. and 800–950% elongation) were obtained when the final crosslink density was in the range 1.0–1.6 × 10−4 moles of effective chains/cc. Use of the synthetic cis‐polyisoprene latex in production of foam is described. Gelation with sodium silicofluoride at room temperature occurs within 2–10 minutes. Production of a controlled level of crosslinking in the latex prior to frothing and gelling was found to improve the uniformity of cell structure of foams and to increase their resistance to compression. Excessive crosslinking in the latex during maturation was shown to cause a loss of tensile strength in cured products presumably because the coalescence of latex particles during gelation is adversely affected. The properties of synthetic cis‐1,4‐polyisoprene latices and the physical properties of films and foams derived from them are shown in general to be very similar to those of natural rubber latex and its products.

Titer Compounding of Neoprene Latex

Abstract The practical importance of free alkali content on the processing and storage life of Neoprene latexes, both raw and compounded, is demonstrated. It is shown that titer measurements are more sensitive than pH measurements for establishing the alkali level of Neoprene latex, that increasing amounts of alkali increase markedly the life of both raw and compounded latexes, that increasing amounts of alkali decrease the original viscosity of compounds and reduce very much the viscosity increase which takes place during aging but, that, within the ranges checked, the alkali content has little effect on the physical properties of films. A procedure for measuring accurately and adjusting easily the free alkali content of raw latex to a desired level is suggested.

Procedure for Determining Physical Properties of Films from GR-S Latices

Abstract This article describes a new procedure for determining the physical properties of films from GR-S type of synthetic rubber latices. To obtain satisfactory films for testing, the latex solids should be above 30 per cent. A suitable formulation which will reach the optimum cure in from 30 to 60 minutes at 100° C is as follows: Polymer 100.0 Sulfur 2.0 Zinc oxide 3.0 Zinc mercaptobenzothiazole 1.5 Zinc dibutyldithiocarbamate 0.5 If zinc mercaptobenzothiazole is to be omitted, it is desirable to increase the dithiocarbamate to about 1.0 part. If the dithiocarbamate is not used, vulcanization should be carried out at higher temperatures, e.g., 120° C. These vulcanizing ingredients may be used as a composite dispersion by ball-milling the accelerator, sulfur and zinc oxide with 0.5 parts dispersing agent, such as Daxad-11, Vultramine, etc., to give a 45 to 50 per cent dispersion. It is recommended that freshly prepared pastes be used, since experience has shown that erratic results may be obtained when old pastes are used, particularly those containing zinc oxide. Additional stabilizers, such as soap, may be used with this compound if required in some cases. Films should be prepared promptly after the compound is made, for prevulcanization may occur in the final films and produce erratic results.

Coating Composition Films Physical Properties and Durability

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCoating Composition Films Physical Properties and DurabilityJames K. Hunt and W. D. LansingCite this: Ind. Eng. Chem. 1935, 27, 1, 26–29Publication Date (Print):January 1, 1935Publication History Published online1 May 2002Published inissue 1 January 1935https://doi.org/10.1021/ie50301a006RIGHTS & PERMISSIONSArticle Views65Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (621 KB) Get e-Alerts