Effect of Low-Temperature Oxygen Plasma Treatment of Titanium Alloy Surface on Tannic Acid Coating Deposition.

In this study, the effect of low-temperature oxygen plasma treatment with various powers of a titanium alloy surface on the structural and morphological properties of a substrate and the deposition of a tannic acid coating was investigated. The surface characteristics of the titanium alloy were evaluated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. Following this, the tannic acid coatings were deposited on the titanium alloy substrates and the structural and morphological properties of the tannic acid coatings deposited were subject to characterization by XPS, SEM, and spectroscopic ellipsometry (SE) measurements. The results show that the low-temperature oxygen plasma treatment of titanium alloys leads to the formation of titanium dioxides that contain -OH groups on the surface being accompanied by a reduction in carbon, which imparts hydrophilicity to the titanium substrate, and the effect increases with the applied plasma power. The performed titanium alloy substrate modification translates into the quality of the deposited tannic acid coating standing out by higher uniformity of the coating, lower number of defects indicating delamination or incomplete bonding of the coating with the substrate, lower number of cracks, thinner cracks, and higher thickness of the tannic acid coatings compared to the non-treated titanium alloy substrate. A similar effect is observed as the applied plasma power increases.

Modification of Polycaprolactone with Plant Extracts to Improve the Aging Resistance.

Natural extracts of plant origin are used as anti-aging compounds of biodegradable polymers. Coffee, cocoa, or cinnamon extracts in amounts from 0.5 to 10 wt.% were added to the polycaprolactone matrix. The manufactured materials were aged at elevated temperatures with increased relative humidity and continuous exposure to UV radiation for 720, 1440, or 2160 h. The performance of the proposed extracts was compared with the retail anti-aging compound, butylated hydroxytoluene. Visual assessment, FTIR analysis, melt flow rate, tensile strength, impact tensile strength, thermogravimetry, and differential scanning calorimetry tests were conducted. Results showed that the use of lower contents of the tested extracts is particularly advantageous. When the content of the extract did not exceed 1 wt.%, no unfavorable influence on the properties of the materials was observed. The stabilizing performance during accelerated aging was mostly similar to or greater than that of the reference compound used.

The structure and selected properties of poly(ε-caprolactone)-based biodegradable composites with high calcium carbonate concentration.

The article refers to new polycaprolactone (PCL) composites with high concentration of calcium carbonate (CC). The objective of the present study was the manufacturing of PCL-based biodegradable composites, containing from 24 to 75 % of CC by mass, along with analyses of changes in selected properties of the obtained PCL composites, occurring upon various amounts of CC. Importantly, in the study relatively cheap and unmodified kind of CC has been used to determine the changeover cost of produced composites. Qualitative and quantitative analyses in addition to structure analysis of the obtained composites, including the distribution of the filler particles and their average dimensions were conducted. Furthermore, the mechanical and thermal properties, mass melt flow rate and the density have been determined. Finally, a commercially important economic analysis has been presented. A significant influence of CC on the mechanical properties of PCL was found. Specifically, the reduction of its relative elongation at break and impact strength, as well as the increase of its flexural modulus and bending strength. An increase in the thermal stability of the produced composites was also observed, however the characteristic temperatures of phase transitions as well as the degree of crystallinity did not change significantly. Considering the results of the density tests, an increase in the CC content resulted in a significant decrease in the unit price of the produced composites. This is of particular application importance, because a lower cost material with new properties could be obtained.

Polycaprolactone-Based Films Incorporated with Birch Tar-Thermal, Physicochemical, Antibacterial, and Biodegradable Properties.

We present new polymer materials consisting of polycaprolactone (PCL), polyethylene glycol (PEG), and birch tar (D). PEG was introduced into the polymer matrix in order to obtain a plasticizing effect, while tar was added to obtain antibacterial properties and to change the physicochemical properties of the film. The materials were obtained by the solvent method and characterized using a variety of methods to test their performance and susceptibility to biodegradation. The obtained data indicate that the introduction of the bioactive substance (D) into PCL improved the thermal stability and significantly lowered the Young's modulus values of the tested polymers. Moreover, the addition of birch tar improved the barrier and bacteriostatic properties, resulting in a reduction in the growth of pathogenic bacteria on the surface of the film. The films are not mutagenic but are susceptible to biodegradation in various environments. Due to their properties, they have potential for application in agriculture and horticulture and for packaging food, mainly vegetables grown in the field.

Birch Tar Introduced into Polylactide and Its Influence on the Barrier, Thermal, Functional and Biological Properties of the Film Obtained by Industrial Extrusion.

The aim of the study was to evaluate possibility of producing a polylactide film with birch tar by the industrial extrusion method and whether the addition of 10% birch tar can ensure adequate biocidal properties of PLA against pathogenic microorganisms (E. coli, S. aureus, P. aeruginosa, A. tumefaciens, X. campestris, P. brassicacearum, P. corrugate and P. syringae) and fungi (A. niger, A. flavus and A. versicolor) while ensuring beneficial functional properties, such as water vapor, nitrogen, oxygen and carbon dioxide permeability, which are of considerable importance in the packaging industry. The main test methods used were ISO 22196, ISO 846, ISO 2556, ASTM F 1927 and ASTM F 2476-20. The obtained results prove the possibility of extruding polymer films with a biocidal additive, i.e., birch tar, and obtaining favorable properties that qualify the produced film for applications in the packaging industry.

Copper Electroless Metallization of Cellulose Paper via Polydopamine Coating and Silver Catalyst.

The paper presents the results of copper electroless metallization of cellulose paper with the use of a polydopamine coating and silver catalyst. The polydopamine coating was deposited via a simple dip method using a dopamine hydrochloride solution in 10 mM TRIS-HCl buffer with a pH of 8.5. The research showed that as a result of this process, cellulose fibers were covered with a homogeneous layer of polydopamine. The unique properties of the polydopamine coating allowed the reduction of silver ions from silver nitrate solution and the deposition of silver atoms on the paper surface. Deposited silver served as a catalyst in the autocatalytic electroless copper-plating process. The copper layer covered the entire surface of the paper sheet after 5 min of metallization, favorably affecting the electrical properties of this material by lowering the surface resistivity. The deposited copper layer was further characterized by good adhesive strength and high susceptibility to deformation.

New Organophilic Montmorillonites with Lactic Acid Oligomers and Other Environmentally Friendly Compounds and Their Effect on Mechanical Properties of Polylactide (PLA).

New organophilic montmorillonites with oligomers of lactic acid and other compounds such as citric acid, stearic acid, maleic anhydride, pentaerythritol and ε-caprolactone were synthesized. They were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), elemental analysis and swelling capacity in water. In all tested composites, an increase in the montmorillonite interlayer distance resulting from intercalation of the modifying substance in the montmorillonite was found by means of XRD. Elemental analysis and FTIR showed that all of the tested samples contained an organic segment in the montmorillonite structure. TGA studies revealed that composites modified with lactic acid oligomers, stearic acid or ε-caprolactone had the highest thermal stability. They also exhibited the lowest swelling capacity which was 2-3 times lower than that for unmodified sodium montmorillonite. Some preliminary studies on the mechanical properties of PLA/modified montmorillonite are also presented and discussed.

Laser Activated and Electroless Metalized Polyurethane Coatings Containing Copper(II) L-Tyrosine and Glass Microspheres.

Polyurethane coatings containing copper(II) L-tyrosine and glass microspheres were laser irradiated and underwent electroless metallization. Various sizes of glass microspheres were incorporated into the polyurethane coating matrix in order to examine their effects on surface activation and electroless metallization. The surface of the coatings was activated by using ArF excimer laser emitting ultraviolet radiation (λ = 193 nm) using different number of laser pulses and their fluence. The effects of surface activation and metallization were evaluated mainly based on optical and scanning electron microcopies (SEM), energy-dispersive X-ray spectroscopy (EDX) and photoelectron spectroscopy (XPS). It was found that the presence of glass microspheres enabled the reduction in copper complex content, intensified the ablation process (higher cone-like structures created) and resulted in higher content of copper metallic seeds. On the other hand, the glass microspheres concentration, which was higher for lower size microspheres, was advantageous for obtaining a fully metallized layer.

Bactericidal and Fungistatic Properties of LDPE Modified with a Biocide Containing Metal Nanoparticles.

The aim of this study was to ascertain whether the combined action of metal nanoparticles (silver, copper, zinc oxide, iron oxide) would ensure the appropriate biocidal properties oflow-density polyethylene (LDPE) against pathogenic microorganisms. According to the research hypothesis, appropriately selected concentrations of the applied metal nanoparticles allow for a high level of biocidal activity of polymeric materials against both model and pathogenic bacterial strains (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Legionella pneumophila, Salmonella enterica subsp. enterica) and fungi (Aspergillus brasiliensis, Saccharomyces cerevisiae, Candida albicans, Penicilium expansum), whilst ensuring the safety of use due to the lack of migration of particles to the surrounding environment. Studies have shown that adding 4% of a biocide containing Ag, Cu, ZnO, and Fe2O3 nanoparticles is the most optimal solution to reduce the number of S. aureus, S. enterica and P. aeruginosa by over 99%. The lowest effectiveness was observed against L. pneumophila bacteria. As for E. coli, a higher biocide content did not significantly increase the antibacterial activity. The results showed a high efficiency of the applied biocide at a concentration of 2% against fungal strains. The high efficiency of the obtained biocidal results was influenced by the uniform dispersion of nanoparticles in the material and their low degree of agglomeration. Furthermore, a slight migration of components to the environment is the basis for further research in the field of the application of the developed materials in industry.

Copper Filled Poly(Acrylonitrile-co-Butadiene-co-Styrene) Composites for Laser-Assisted Selective Metallization.

Selective metallization of polymeric materials using the technique known as laser direct structuring (LDS) is intensively developed. In this technique, metallized products can be manufactured by injection molding or by 3D printing process if rapid prototyping is need. Special additives present in the polymer matrix enable direct electroless metallization only on the surface which was laser activated. This paper presents the results of using copper microparticles introduced into the poly(acrylonitrile-butadiene-styrene) (ABS) matrix at various amounts (up to about 5 vol %). ABS was selected due to its good processing and mechanical properties and as one of the most common thermoplastics used in 3D printing. The influence of copper on structural, mechanical, and processing properties as well as on the effects of laser surface activation were determined. Two types of infrared lasers were tested for surface activation: Nd:YAG fiber laser (λ = 1064 nm) and CO2 laser (λ = 10.6 µm). Various irradiation parameters (power, scanning speed, and frequency) were applied to find suitable conditions for laser surface activation and electroless metallization. It was found that the composites tested can be effectively metallized using the Nd:YAG laser, but only in a narrow range of radiation parameters. Activation with CO2 laser failed, regardless of applied irradiation conditions. It resulted from the fact that ablation rate and thickness of modified surface layer for CO2 were lower than for Nd:YAG laser using the same irradiation parameters (power, speed, and frequency of laser beams), thus the laser wavelength was crucial for successful surface activation.

Studies on the Uncrosslinked Fraction of PLA/PBAT Blends Modified by Electron Radiation.

The results of studies on the uncrosslinked fraction of blends of polylactide and poly(butylene adipate-co-terephthalate) (PLA/PBAT) are presented. The blends were crosslinked by using the electron radiation and triallyl isocyanurate (TAIC) at a concentration of 3 wt %. Two kinds of samples to be investigated were prepared: one contained 80 wt % PLA and the other contained 80 wt % PBAT. Both blends were irradiated with the doses of 10, 40, or 90 kGy. The uncrosslinked fraction was separated from the crosslinked one. When dried, they were subjected to quantitative analysis, Fourier transform infrared spectroscopy (FTIR) measurements, an analysis of variations in the average molecular weight, and the determination of thermal properties. It was found that the electron radiation caused various effects in the studied samples, which depended on the magnitude of the radiation dose and the weight fractions of the components of the particular blends. This was evidenced by the occurrence of the uncrosslinked fractions of different amounts, a different molecular weight distribution, and the different thermal properties of the samples. It was also concluded that the observed effects were caused by the fact that the processes of crosslinking and degradation took place mostly in PLA, while PBAT appeared to be less susceptible to the influence of the electron radiation.

Composting of Polylactide Containing Natural Anti-Aging Compounds of Plant Origin.

The paper presents the effects of biodegradation of polylactide containing natural anti-aging compounds. Polymer containing 0.5; 5 and 10 wt % of coffee, cocoa or cinnamon extracts were subjected to industrial composting for 7, 14, 21 or 28 days. The effect of the composting process on polylactide properties was examined based on visual assessment, scanning electron microscopy, average molecular weight, differential scanning calorimetry, thermogravimetry, and tensile strength. The impact of the tested extracts on the effects of the composting process was compared with the impact of a commercially available anti-aging compound. It was found that the tested extracts in most cases did not adversely affect the effects of the composting process compared to pure polylactide, often resulting in intensification of biodegradation processes. As a result of the composting process, changes in the macro- and microscopic appearance of the samples and a decrease in molecular weight, phase transition temperatures, thermal resistance, and thermal strength were observed on a scale close to or greater than the reference anti-aging compound.

The Effect of Accelerated Aging on Polylactide Containing Plant Extracts.

In this study, natural extracts of plant origin were used as anti-aging compounds of biodegradable polymers. Coffee (0.5⁻10 wt%), cocoa, or cinnamon extracts were added to the polylactide matrix. The obtained materials were subjected to an accelerated aging process (720, 1440, or 2160 h) at 45 °C and 70% relative humidity under continuous UV radiation. The effectiveness of the tested extracts was compared to a commercially available anti-aging compound, 2 wt% of butylated hydroxytoluene. Visual evaluation, scanning electron microscopy, melt flow rate, thermogravimetry, differential scanning calorimetry, tensile strength, and impact tensile tests were performed. We show that the use of smaller amounts of tested extracts is particularly advantageous, which do not adversely affect the properties of polylactide-based materials at low contents. At the same time, their effectiveness in stabilizing tested properties during the accelerated aging process is mostly comparable to or greater than the reference compound.

Forensic engineering of advanced polymeric materials. Part III - Biodegradation of thermoformed rigid PLA packaging under industrial composting conditions.

This paper presents a forensic engineering study on the biodegradation behaviour of prototype packaging thermoformed from PLA-extruded film and plain PLA film under industrial composting conditions. Hydrolytic degradation in water was conducted for reference. The effects of composting duration on changes in molar mass, glass transition temperature and degree of crystallinity of the polymeric material were monitored using gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The chemical structure of water soluble degradation products of the polymeric material was determined using nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS). The results show that the biodegradation process is less dependent on the thermoforming process of PLA and more dependent on the composting/degradation conditions that are applied. The increase in the dispersity index, leading to the bimodal molar mass distribution profile, suggests an autocatalytic hydrolysis effect at the early stage of the composting process, during which the bulk hydrolysis mechanism dominantly operates. Both the prototype PLA-packaging and PLA rigid film samples were shown to have a gradual increase in opacity due to an increase in the degree of crystallinity.