Search results for "Contact angle"
showing 10 items of 138 documents
Characteristics of industrially manufactured amorphous hydrogenated carbon (a-C:H) depositions on high-density polyethylene
2016
Industrially high-density polyethylene (HDPE) was successively covered by two types of amorphous hydrogenated carbon (a-C:H) films, one more flexible (f-type) and the other more robust (r-type). The films have been grown by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique with acetylene plasma. The surface morphology of both types has been studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Contact angle measurements and Raman spectroscopy analysis were done to investigate the surface wettability and carbon chemical composition. Both types display similar morphology and grain growth pattern. Contact angle measurements revealed surfa…
The Grain Boundary Wetting Phenomena in the Ti-Containing High-Entropy Alloys: A Review
2021
In this review, the phenomenon of grain boundary (GB) wetting by melt is analyzed for multicomponent alloys without principal components (also called high-entropy alloys or HEAs) containing titanium. GB wetting can be complete or partial. In the former case, the liquid phase forms the continuous layers between solid grains and completely separates them. In the latter case of partial GB wetting, the melt forms the chain of droplets in GBs, with certain non-zero contact angles. The GB wetting phenomenon can be observed in HEAs produced by all solidification-based technologies. GB leads to the appearance of novel GB tie lines Twmin and Twmax in the multicomponent HEA phase diagrams. The so-cal…
Green Composites Based on PLA and Agricultural or Marine Waste Prepared by FDM
2021
Three dimensional-printability of green composites is recently growing in importance and interest, especially in the view of feasibility to valorize agricultural and marine waste to attain green fillers capable of reducing bioplastic costs, without compromising their processability and performance from an environmental and mechanical standpoint. In this work, two lignocellulosic fillers, obtained from Opuntia ficus indica and Posidonia oceanica, were added to PLA and processed by FDM. Among the 3D printed biocomposites investigated, slight differences could be found in terms of PLA molecular weight and filler aspect ratio. It was shown that it is possible to replace up to 20% of bioplastic …
Modified arabinoxylan-based films
2004
Abstract Oxygen plasma and electron beam irradiation were used to graft hydrophobic substances and by this way, to reduce water vapor permeability (WVP) of arabinoxylan-based (AX-based) films. Stearyl acrylate (SA) and stearyl methacrylate (SM) were used as reactive monomers. The homogeneous AX-based films, which were pre-activated by oxygen plasma and impregnated with a solution of SA before being exposed to an electron beam (EB), had contact angles that increased from 71° (untreated films) to 122° (treated films). A decrease of about 24% in the WVP was obtained and new chemical groupings were observed on the FTIR spectra of these films. Acrylate monomers were also dispersed into the arabi…
The influence of the nature of the surface oxide on the adhesive fracture energy of aluminium-bonded joints as measured by T-peel tests
2008
Abstract Modification of aluminium alloy substrates microstructure and morphology by depositing new oxide layers on top of the metal surface has been investigated, with the aim of improving adhesion. The effect of treating the metal with boiling water or immersing it in a cerate bath has been studied by means of electron microscopy, contact angle measurements and peeling tests. The formation of pseudoboehmite layers or cerium conversion coatings both led to an increase in joint's adhesive fracture energy and more durable adhesive bonds with respect to joints obtained with “mechanically grinded only” substrates. Differences in the performance of the bonded joints has been discussed in terms …
Preparation and photoactivity of samarium loaded anatase, brookite and rutile catalysts
2011
Abstract Pure and samarium loaded anatase, brookite and rutile nanopowders were synthesized by thermohydrolysis of TiCl 4 . The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (SSA) determination, UV–vis diffuse reflectance spectroscopy (DRS), atomic force microscopy (AFM), contact angle (CA) measurements and photoluminescence (PL) spectroscopy. The photocatalytic activity of pure and Sm-loaded TiO 2 polymorphs was investigated by employing the photodegradation of 4-nitrophenol as probe reaction in a liquid-solid system. Loading with Sm resulted in an improvement of the photoreactivity of the three TiO 2 polymorphs. The benefi…
Halloysite nanotubes loaded with peppermint essential oil as filler for functional biopolymer film
2016
Abstract The purpose of this paper is to show how a functional bionanocomposite film with both antioxidant and antimicrobial activities was successfully prepared by the filling of a pectin matrix with modified Halloysite nanotubes (HNT) containing the essential peppermint oil (PO). Firstly, HNT surfaces were functionalized with cucurbit[6]uril (CB[6]) molecules with the aim to enhance the affinity of the nanofiller towards PO, which was estimated by means of HPLC experiments. The HNT/CB[6] hybrid was characterized by several methods (thermogravimetry, FT-IR spectroscopy and scanning electron microscopy) highlighting the influence of the supramolecular interactions on the composition, therma…
Real-time microfluorescence studies of Langmuir-Blodgett deposition: Monolayer adsorption and desorption
1990
Abstract Observations of the meniscus region in a typical Langmuir-Blodgett configuration are obtained using fluorescence microscopy. Studies of the meniscus position as a function of pH demonstrate that the meniscus height increases upon charging the monolayer owing to the repulsive interaction between monolayer and substrate surfaces. Through the correspondence between meniscus height and contact angle the adhesion forces between monolayer and substrate as a function of monolayer charge are assessed. The phenomenon of desorption upon resubmerging a deposited film is described and it is shown that the meniscus height at the onset of the desorption is greater for higher pH.
Study on carvacrol and cinnamaldehyde polymeric films: mechanical properties, release kinetics and antibacterial and antibiofilm activities.
2012
Polyethylene-co-vinylacetate (EVA) films with different concentrations (3.5 wt% and 7 wt%) of essential oil constituents, carvacrol or cinnamaldehyde, were prepared and characterized by mechanical, antibacterial and antibiofilm properties. The incorporation of the compounds into copolymer films affected their elastic modulus, tensile stress and elongation at break. Carvacrol and cinnamaldehyde act as plasticizers which reduce the intermolecular forces of polymer chains, thus improving the flexibility and extensibility of the film. The analysis of the surface characteristics demonstrated that essential oil constituents lowered the contact angle values without causing any remarkable variation…
Edible Arabinoxylan-Based Films. 1. Effects of Lipid Type on Water Vapor Permeability, Film Structure, and Other Physical Characteristics
2002
Arabinoxylans (AX) are natural fibers extracted from maize bran, an industrial byproduct. To promote this polymer as a food ingredient, development of edible coatings and films had been proposed. Indeed, composite arabinoxylan-based films were prepared by emulsifying a fat: palmitic acid, oleic acid, triolein, or a hydrogenated palm oil (OK35). Lipid effects on water vapor permeability (WVP), surface hydrophobicity (contact angles), lipid particle size, and mechanical properties were investigated. Results showed that OK35-AX emulsion films had the lowest WVP. Emulsified films presented a bimodal particle size distribution; however, the smallest particle mean diameter (0.54 microm) was obser…