| Gas permeability is one of the important properties of polymers, such as fabric membranes and coating films. It relates to the structure, phase state and molecular movement.In this paper,polyacrylate films are made and their gas permeability are tested. Permeability coefficients are calculated by using Fick's First Law. It can be concluded that membrane density, functional groups, curing degree and water absorption can greatly impact the gas permeability of polyacrylate films.Styrene-acrylic emulsion which is an important intermediate product in chemical industry has a broad range of uses. Hardness, gloss and hydrophile of films made by styrene-acrylic coatings have a great impact on coatings performance.Styrene-acrylic emulsion which have different monomer ratio are synthesized, and their hardness, gloss and contact angle are measured. Multiple linear regression was applied to create mathematical models which related to monomers and coatings properties. It can be concluded that, monomer ratio can affect coating's hardness, gloss and contact angle. It will be the guide for preparation coatings.1. Factors impacting on gas permeabilityIn my experiments, films made by the same emulsion have some different densities. It can be presumed the difference is caused by the structure of films. Experiments data show that, the density of films is higher, gas permeability is lower.In this thesis, the impact of phenyl and carboxyl are also considered. It can be concluded that phenyl is beneficial for gas permeability and carboxyl makes against gas permeability. Phenyl is a hydrophobic functional group and its steric effect, so water molecular is not easy to form hydrogen bond. Therefore, polyacrylate films which have more phenyl will represent better gas permeability and greater permeability coefficient. However, Carboxyl is a hydrophilic functional group and it is favorable for water absorption .Therefore, polyacrylate films which have more carboxyl will behave better water absorption and less gas permeability.A formula of emulsion which consists of five monomers is designed for researching the relation between curing degree and gas permeability. By testing curing degree and gas permeability of this emulsion films, we can summarize that curing degree is better, gas permeability is lower. Esterification can take place between acrylic acid and hydroxyethyl acrylate which will increase density and curing degree of polyarylate films. As density and curing degree of polyarylate films improved, molecular weight of polymers increased, more compacted films can be acquired. Therefore, films which have better curing degree manifested smaller gas permeability and permeability coefficient.2. Properties Modeling of Polyacrylate CoatingsIn this paper, styrene-acrylic emulsions containing BA, MMA and St are synthesized. Polyacrylate coatings are prepared by using styrene-acrylic emulsions and hardness, gloss and contact angle of coatings are tested. Mathematical models which could reflect the relation between monomers and coatings properties are created by making use of multiple linear regression. Three mathematical models are as follows:YD(BA,MMA,St)=ï¹£10.6232BA+20.5291MMA+24.0948St (1)GZD(BA,MMA,St)=ï¹£0.0737BA+0.0615MMA+0.1708St (2)JCJ(BA,MMA,St)=2.065BA+2.1575MMA+4.8522St (3)From mathematical models (1)(2)(3), we can make some conclusions. The regression coefficients of styrene are positive and greater in models (1)(2)(3), so styrene can most greatly affect hardness, gloss and contact angle of polyacrylate coatings. Hardness, gloss and contact angle can greatly improved by adding amount of styrene.Methyl methacrylate's regression coefficients in models (1)(2)(3) are all positive, so hardness, gloss and contact angle will increase if amount of methyl methacrylate can be advanced.In models (1)(2), the regression coefficients of butyl-acrylate are negative, for that reason we can decrease polyacrylate coatings' hardness and gloss by cutting down the quantity of butyl-acrylate in emulsions.
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