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A procedure is described of grafting the acrylic acid onto an oxygen/ozone-activated metallocene poly(ethylene-co-propylene). Consequently, the grafted copolymer is applied as a component in a metallocene polyolefin-based hot-melt adhesive composition with increased adhesion. The surface properties and adhesion strength of the prepared hot-melt adhesive (HMA) were determined and used to account for the effect of grafting. The application of grafted polyolefin as one of the components of the HMA mixture provides significant increase in adhesive strength, and it also results in increased compatibility and negligible effects on the technological parameters of the final composition. The obtained results may have significant impact for the practical application of prepared HMA for book bonding. [ABSTRACT FROM AUTHOR]

Industrially important properties of wood can be changed due to the modification of birch wood (Betula pendula L.) after the process of thermal treatment with saturated water steam. The birch wood was modified by saturated water steam at 125 ± 2.5 °C for 8 hours and at a pressure of 0.18 MPa. The water contact angle of steam-treated birch wood increased from 42.1° (for untreated birch wood) to 52.4° (for steam-treated birch wood), and the stability of water drop on steam-treated birch wood surface increased. FTIR spectra showed an increase in C=O and glycoside bonds concentration on the surface of steam-treated birch wood, but the concentration of C-O-C groups decreased. XPS measurements confirmed that the concentration of oxygen as well as C=O and C-O-O groups on the surface of steamtreated birch wood showed an increment in comparison with the native wood sample. SEM micro photos confirmed the minor changes of birch wood cells due to the action of saturated water steam modification. [ABSTRACT FROM AUTHOR]

Commercial metallocene ethylene–octene random copolymer, Resinex PE RXP 1502 (RXP), was grafted with acrylic or crotonic acid in the solution and in the melt to increase the RXP's polarity and adhesion to cellulose-based substrates. Acrylic or crotonic acids were grafted on the RXP macromolecules which were activated with an oxygen–ozone mixture. The formed graft copolymer was tested as additive to a hot melt adhesive (HMA) improving adhesive properties. The most effective procedure was to graft RXP with acrylic acid in the melt, while grafting activated RXP in a toluene solution was less efficient. The melt grafting efficiency is high and varies between 0.77 and 0.97. The RXP polarity after grafting increases significantly, as there is a 15% decrease in the water contact angle and an increase in the surface energy and its polar component by 1.1–1.7 times as compared to the virgin RXP. The heat-fail temperature resistance in peel of RXP grafted with acrylic and/or crotonic acid increased by more than 10°C, while the heat-fail temperatures of adhesive joints in shear tests were similar. The adhesive joint peel strength increased 1.2 times. The cardboard–HMAs based on virgin RXP adhesive joint peel tests exhibit adhesive failure, whereas the cardboard–HMAs containing grafted RXP joints show cohesive failure. [ABSTRACT FROM AUTHOR]

An investigation was made of wood of the species oak (Quercus petraea), beech (Fagus sylvatica L.), maple (Acer pseudoplatanus) and ash (Fraxinus excelsior) pre-treated using radio-frequency (RF) plasma in air at reduced pressure. Physical and chemical changes for all of the wood species were determined using measurements of water contact angles and FTIR-ATR spectroscopy. The results confirmed an increase in the wood’s hydrophilicity/polarity in all cases, caused by an increase in –OH group concentration due to irradiation by RF plasma. The content of oxygen-containing functional groups after treatment by RF plasma significantly increased, and the water contact angles were diminished. FTIR-ATR spectroscopy confirmed that RF plasma modification of the surfaces of all investigated wood samples led to certain changes, which were also dependent on the time of plasma exposure. [ABSTRACT FROM AUTHOR]

In this paper, diffuse coplanar surface barrier discharge plasma at atmospheric pressure has been used for surface modification of polyester/cotton (PESc) fabric, which was subsequently modified by sol–gel process using suitable organofunctional silanes to enhance its hydrophobicity. Modified PESc fabric surfaces were conditioned during the gelling process to obtain the permanent hydrophobicity. The contact angle of water before washing of plasma and sol–gel pretreated PESc fabric was found to be 154° and 151° after standardized washings. It was also demonstrated that the process is applicable at the industrial scale. [ABSTRACT FROM AUTHOR]

Polymers/metal laminates are often used to improve physical and mechanical properties, especially those required in building applications. A flat aluminum composite panel (ACP) consisted mainly of two thin metal sheets usually made of aluminum (Al) and a non-metal core, such as polyethylene (PE). The lack of adhesion associated with the low wettability of PE is a serious problem. An eco-friendly, dry, non-destructive corona treatment technique can be applied to solve this problem. In this work, the use of a corona treatment to enhance the adhesion properties of linear low-density polyethylene (LLDPE) was studied. The changes in surface and adhesion properties were thoroughly analyzed using various analytical techniques and methods to obtain the optimal parameters for corona discharge using contact angle measurements, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). AFM force adhesion measurements were used to analyze the effect of the corona treatment on the adhesion enhancement of LLDPE, and the peel tests confirmed a significant increase in peel resistance in the LLDPE/Al laminate. A synergy effect from using the corona treatment in combination with an ethylene acrylic acid dispersion primer was observed. [ABSTRACT FROM AUTHOR]

Investigation was made into the effect of plasma treatment on the release kinetics of the drug Temozolomide (TMZ) from thin, biodegradable polyester films, comprising polylactic acid (PLA) and polyester urethane. The authors utilized two systems to achieve this, the first being diffuse coplanar surface barrier discharge, applying air as the gaseous medium, while the other involved capacitively coupled radio frequency discharge plasma under an argon atmosphere with hexamethyldisiloxane. Results showed that both forms of plasma treatment positively reduced the undesirable burst effect and benefited the release rate of TMZ. The hydrolytic degradability of the materials was slightly enhanced following hydrophilization, whereas the same diminished after hydrophobization had taken place. This was especially true for PLA due to modification of its wettability. [ABSTRACT FROM AUTHOR]

A barrier plasma, created at atmospheric pressure, was used to improve the surface and adhesive properties of polyester (PES) film with respect to wood using polyurethane adhesives. The modification of PES film surfaces using barrier discharge plasma is attractive for various applications. Plasma pre-treatment initiates and participates in grafting, polymerization, or cross-linking reactions on the PES surface. This method of surface modification is clean, dry, ecological, and very efficient. The enhancement of the wettability of the polyester film was necessary for promoting higher adhesion to wood with water-based adhesives. The treatment of polyester films by barrier plasma led to a considerable increase in the surface free energy of the film and subsequently an increase in the peel strength of the adhesive joint of PES film-oak wood with polyurethane adhesive. [ABSTRACT FROM AUTHOR]

Low-temperature plasma was used to improve the surface and adhesive properties of wood. The pre-treatment of wood surfaces using radio-frequency (RF) discharge plasma is attractive for various wood applications, mainly because of the high efficiency and low production cost of the process. In addition, a significant increase in the polar component of the wood surface energy, which is associated with the presence of acid–base interactions (electron donor–acceptor bonds), after modification by RF discharge plasma was identified. The treatment of wood by RF plasma exhibited an aging effect, with the modified surface never recovering its initial hydrophobic state. Indeed, the enhancement of the wettability of wood is necessary for promoting better adhesion with water-based adhesives and coatings, which is currently the subject of ongoing study. [ABSTRACT FROM AUTHOR]

Abstract: Low-density polyethylene (LDPE) belongs to commodity polymer materials applied in biomedical applications due to its favorable mechanical and chemical properties. The main disadvantage of LDPE in biomedical applications is low resistance to bacterial infections. An antibacterial modification of LDPE appears to be a solution to this problem. In this paper, the chitosan and chitosan/pectin multilayer was immobilized via polyacrylic acid (PAA) brushes grafted on the LDPE surface. The grafting was initiated by a low-temperature plasma treatment of the LDPE surface. Surface and adhesive properties of the samples prepared were investigated by surface analysis techniques. An antibacterial effect was confirmed by inhibition zone measurements of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The chitosan treatment of LDPE led to the highest and most clear inhibition zones (35mm2 for E. coli and 275mm2 for S. aureus). [Copyright &y& Elsevier]

Polyethylene (PE) is one of the most widely used polymers in many industrial applications. Biomedical uses seem to be attractive, with increasing interest. However, PE it prone to infections and its additional surface treatment is indispensable. An increase in resistance to infections can be achieved by treating PE surfaces with substances containing antibacterial groups such as triclosan (5-Chloro-2-(2,4-dichlorophenoxy)phenol) and chlorhexidine (1,1'-Hexamethylenebis[5-(4-chlorophenyl)biguanide]). This work has examined the impact of selected antibacterial substances immobilized on low-density polyethylene (LDPE) via polyacrylic acid (PAA) grafted on LDPE by low-temperature barrier discharge plasma. This LDPE surface treatment led to inhibition of Escherichia coli and Staphylococcus aureus adhesion; the first causes intestinal disease, peritonitis, mastitis, pneumonia, septicemia, the latter is the reason for wound and urinary tract infections. [ABSTRACT FROM AUTHOR]

Abstract: Medical-grade polyvinyl chloride was surface modified by a multistep physicochemical approach to improve bacterial adhesion prevention properties. This was fulfilled via surface activation by diffuse coplanar surface barrier discharge plasma followed by radical graft copolymerization of acrylic acid through surface-initiated pathway to render a structured high density brush. Three known antibacterial agents, bronopol, benzalkonium chloride, and chlorhexidine, were then individually coated onto functionalized surface to induce biological properties. Various modern surface probe techniques were employed to explore the effects of the modification steps. In vitro bacterial adhesion and biofilm formation assay was performed. Escherichia coli strain was found to be more susceptible to modifications rather than Staphylococcus aureus as up to 85% reduction in adherence degree of the former was observed upon treating with above antibacterial agents, while only chlorhexidine could retard the adhesion of the latter by 50%. Also, plasma treated and graft copolymerized samples were remarkably effective to diminish the adherence of E. coli. [Copyright &y& Elsevier]

Medical-grade polyvinyl chloride was coated by polysaccharides through a novel physicochemical approach. An initial surface activation was performed foremost via diffuse coplanar surface barrier discharge plasma in air at ambient temperature and pressure. Then, radical graft copolymerization of acrylic acid through grafting-from pathway was directed to render a well-defined brush of high density, and finally a chitosan monolayer and chitosan/pectin alternating multilayer were bound onto the functionalized surfaces. Surface characteristics were systematically investigated using several probe techniques. In vitro bacterial adhesion and biofilm formation assays indicated that a single chitosan layer was incapable of hindering the adhesion of a Staphylococcus aureus bacterial strain, while up to 30% reduction was achieved by the chitosan/pectin layered assembly. On the other hand, chitosan and chitosan/pectin multilayer could retard Escherichia coli adhesion by 50% and 20%, respectively. Furthermore, plasma treated and graft copolymerized samples were also found effective to diminish the degree of adherence of Escherichia coli. [ABSTRACT FROM AUTHOR]

Electro-conductive resins, convenient for casting and coating applications were investigated in this paper.Electrical conductivity of epoxy and polyurethane resins, filled with two different grades of synthetic graphite (different average size) was studied. It was found that all the investigated composites became electro-conductive when filled with 22-vol% of the filler.The impact strength of epoxy and polyurethane resins filled with graphite was also investigated. A decrease in impact strength with an increase in filler content was observed in all cases. The highest values of impact strength were found for polyurethane/graphite KS 6 composites.The strength of adhesion of the filled resins to aluminum was also determined. A decrease in the strength of adhesive joints to aluminum foils with an increase in filler content was observed in all cases. The strongest adhesive joints were found for the epoxy/graphite KS 6 composites. [Copyright &y& Elsevier]

Electrical conductivity and elongation at break of epoxy filled with electroconductive carbon black, graphite or with silver-coated basalt particles or fibres were investigated in this paper. Percolation concentrations were determined to be 14 vol% for epoxy/carbon black composites, 22 vol% for epoxy/graphite composites, 28–29 vol% for both epoxy/silver-coated basalt particles and fibres. The steepest increase in electrical conductivity and the most pronounced decrease in elongation at break occurs at similar filler concentration range for all investigated systems. A good correlation between phenomenological model, introduced in [J. Mater. Sci. Lett. 18 (1998) 1457] and experimental data for all investigated systems was observed. [Copyright &y& Elsevier]

Poly(lactide) (PLA) films obtained by thermoforming or solution-casting were modified by diffuse coplanar surface barrier discharge plasma (300 W and 60 s). PLA films were used as hot-melt adhesive in joints in oak wood. It was demonstrated that lap shear strength increased from 3.4 to 8.2 MPa, respectively, for the untreated and plasma-treated series. Pull-off tests performed on particleboard for the untreated and treated PLA films showed 100% cohesive failure. Pull-off strength tests on solid oak demonstrated adhesion enhancement from 3.3 MPa with the adhesion failure mode to 6.6 MPa with the cohesion failure mode for untreated and treated PLA. XPS revealed that carbonyl oxygen content increased by two-to-three-fold, which was confirmed in the Fourier-transform infrared spectroscopy experiments of the treated PLA. The water contact angle decreased from 66.4° for the pristine PLA to 49.8° after treatment. Subsequently, the surface free energy increased from 47.9 to 61.05 mJ/m2. Thus, it was clearly proven that discharge air plasma can be an efficient tool to change surface properties and to strengthen adhesive interactions between PLA and woody substrates. [ABSTRACT FROM AUTHOR]

The use of polycondensation urea-formaldehyde (UF) resins in the woodworking and furniture industries is widespread due to their relatively low price, high reactivity, availability of raw materials, and ease of use. After curing, they provide a transparent, brittle joint, but their main disadvantage is the continuous emission of formaldehyde. The naturally occurring biopolymer keratin and the amino acid cysteine prepared from sheep wool were chosen and tested as possible agents for UF adhesives, allowing the reduction of formaldehyde emissions from wood-based panels. Emissions of formaldehyde were determined in accordance with EN ISO 12460-4. The gluing quality was tested according to standard EN 314-1, and the tested plywood met the requirements of standard EN 314-2. The most significant decrease in formaldehyde emission by up to 44.0% was achieved by applying 1% MOD-I (pre-condensate of glutaraldehyde and urea + cysteine) to the reference UF adhesive. Therefore, samples prepared for this study have great potential for application as environmentally friendly formaldehyde scavengers. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop the potential tissue engineering applications of d -glucosamine (GlcN) immobilized onto the surface of a biodegradable matrix in order to induce a desired biological effect at biointerfaces. Thus, for sample preparation we used a novel multistep physicochemical approach. In the first step the poly(lactic acid) (PLA) films were exposed to a low pressure plasma in air atmosphere, followed by radical graft copolymerization with acrylic acid to yield a carboxyl-functionalized spacer layer on the PLA surface. The carboxyl groups were then coupled to GlcN molecules via the carbodiimide chemistry. The developed surfaces were characterized by X-ray Photoelectron Spectroscopy (XPS), Contact angle measurements and Atomic Force Microscopy (AFM). A preliminary study on the proliferation of fibroblasts on the developed surfaces was performed using the NIH/3T3 cell line. [ABSTRACT FROM AUTHOR]

Non-thermal non-equilibrium oxidative air 40-kHz frequency, 13.56-MHz radiofrequency and 2.46-GHz microwave discharge plasma treatment were used for modifying low-density polyethylene foils. The untreated and treated samples were chemically characterised by X-ray photoelectron spectroscopy. In order to estimate the extent of the plasma sources at distinct treatment times, surface charge and energy were determined by zeta potential (ζ) and surface tension measurements. In addition, the isoelectric points (IEPs) of the studied samples were ascertained, and surface property variations were appraised by ageing time. The overall outcome indicated that ζ-potential and surface energy progressively changed after each treatment, as well as the influences of ageing on surface features, the IEP shifting to lower pH values and how all of these changes are associated with the new surface chemistry. This contribution seeks to shed light on topics related to polymer science and plasma-based strategies for surface modification. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Alginic acid coated polyethylene films were examined in terms of surface properties and bacteriostatic performance against two most representative bacterial strains, that is, Escherichia coli and Staphylococcus aureus. Microwave plasma treatment followed by brush formation in vapor state from three distinguished precursors (allylalcohol, allylamine, hydroxyethyl methacrylate) was carried out to deposit alginic acid on the substrate. Surface analyses via various techniques established that alginic acid was immobilized onto the surface where grafting (brush) chemistry influenced the amount of alginic acid coated. Moreover, alginic acid was found to be capable of bacterial growth inhibition which itself was significantly affected by the brush type. The polyanionic character of alginic acid as a carbohydrate polymer was assumed to play the pivotal role in antibacterial activity. The cell wall composition of two bacterial strains along with the substrates physicochemical properties accounted for different levels of bacteriostatic performance. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Younǵs modulus of the composites increased 13times. [•] The flexural strength of composites was improved 2 times. [•] The polarity of LDPE was significantly enhanced. [•] The adhesion of composites to the polar substrates was improved. [ABSTRACT FROM AUTHOR]

Highlights: [•] The percolation concentration of the filler within the HDPE matrix is 8vol.%. [•] The electrical conductivity of the composite increased in 22 orders. [•] The thermal conductivity of the composite increased four times. [ABSTRACT FROM AUTHOR]

Epoxy resins are materials capable of polymerizing under certain conditions, i.e., a temperature and the presence of a hardener, yielding a three-dimensional net formed by the crosslinking of the chains. This polymerization is also called the curing process. During the curing, different physical processes can be detected, namely, formation of polymer chains and their crosslinking. Thermodynamic and transport characteristics change markedly. A new thermal-conductivity sensor was used for monitoring of the curing process. The principle of the sensor is based on the hot-ball method for measuring the thermal conductivity. The sensor recognizes the processes operating during polymerization. This paper deals with the monitoring of the curing process of diglycidylether of bisphenol A (DGBA) epoxy resin modified with aromatic reactive diluent, where the curing rate is controlled by the temperature and boron trifluoride (BTF) hardener. A short description of the measurement method is given. [ABSTRACT FROM AUTHOR]