Surface modification of high-performance polyimide fibers by oxygen plasma treatment

In order to improve the interfacial compatibility between the fibers and epoxy resins, polyimide (PI) fibers were modified using oxygen plasma with various treatment powers. The properties of PI fibers before and after surface modification were comparatively characterized according to their chemical composition, surface morphology, surface free energy, single filament tensile strength, and interfacial shear strength (IFSS). Most of the fiber properties, including the ratio of oxygen to nitrogen, oxygen concentration, surface free energy, and IFSS firstly increased with the plasma power, and then decreased when the plasma power was higher than 120 W. With a plasma power of 120 W, the oxygen concentration and the ratio of oxygen to carbon atoms (O/C) was 26% (22% for untreated fiber) and 0.38 (0.28 for untreated fiber), respectively. Meanwhile, the values of surface free energy and IFSS were 89% and 30% higher than those for untreated fiber, respectively. Furthermore, the values of single filament tensile strength for modified fibers were only 2.3% lower than those for pristine one. These results indicated that the compatibility between PI fibers and epoxy resins was greatly improved without compromising mechanical properties.

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The Influence of Starch Origin on the Properties of Starch Films: Packaging Performance

Materials ◽

10.3390/ma14051146 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1146

Author(s):

Zuzanna Żołek-Tryznowska ◽

Alicja Kałuża

Keyword(s):

Tensile Strength ◽

Free Energy ◽

Surface Free Energy ◽

Food Packaging ◽

Energy Surface ◽

Free Energy Surface ◽

Casting Method ◽

Starch Solution ◽

Film Properties ◽

Starch Films

Starch films can be used as materials for food packaging purposes. The goal of this study is to compare how the starch origin influence the selected starch film properties. The films were made from various starches such as that from maize, potato, oat, rice, and tapioca using 50%w of glycerine as a plasticizer. The obtained starch-based films were made using the well-known casting method from a starch solution in water. The properties of the films that were evaluated were tensile strength, water vapour transition rate, moisture content, wettability, and their surface free energy. Surface free energy (SFE) and its polar and dispersive components were calculated using the Owens-Wendt-Rabel-Kaelbe approach. The values of SFE in the range of 51.64 to 70.81 mJ∙m−2 for the oat starch-based film and the maize starch-based film. The films revealed worse mechanical properties than those of conventional plastics for packaging purposes. The results indicated that the poorest tensile strength was exhibited by the starch-based films made from oat (0.36 MPa) and tapioca (0.78 MPa) and the greatest tensile strength (1.49 MPa) from potato.

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Surface modification and adhesion improvement of polyester films

Open Chemistry ◽

10.2478/s11532-012-0135-x ◽

2013 ◽

Vol 11 (1) ◽

pp. 35-45 ◽

Cited By ~ 11

Author(s):

Aniello Cammarano ◽

Giovanna Luca ◽

Eugenio Amendola

Keyword(s):

Free Energy ◽

Surface Modification ◽

Surface Free Energy ◽

Self Assembly ◽

Treatment Time ◽

Solution Treatment ◽

Film Surface ◽

Critical Surface ◽

Hydrolysis Time ◽

Critical Surface Tension

AbstractFacile surface modification of polyester films was performed via chemical solutions treatment. Surface hydrolysis was carried out by means of sodium hydroxide solutions, leading to the formation of carboxylate groups. Three commercial polyester films of 100 μm in thickness were used in this work: AryLite™, Mylar™, and Teonex™, hydrolysis time being the main modification parameter. FTIR-ATR analysis, topography and contact angle (CA) measurements, surface free energy (SFE) and T-Peel adhesion tests were carried out to characterize the modified films. A quantitative estimate of the carboxylates surface coverage as a function of treatment time was obtained through a supramolecular approach, i.e. the ionic self-assembly of a tetracationic porphyrin chromophore onto the film surface. The surface free energy and critical surface tension of the hydrolyzed polyesters was evaluated by means of Zisman, Saito, Berthelot and Owens-Wendt methods. It was shown that NaOH solution treatment increases roughness, polarity and surface free energy of polymers. As a result, T-Peel strengths for modified Mylar™ and Teonex™ films were respectively 2.2 and 1.8 times higher than that for the unmodified films, whereas AryLite™ adhesion test failed.

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