D&W Tool Inc.

Role of surface active additives on reduction of surface free energy and enhancing the mechanical Attributes of easy-to-clean automotive clearcoats: Investigating resistance against simulated tree gum

The present study was conducted to recycle waste tire rubber and steel slag (SS) in asphalt pavement and investigates the moisture stability of asphalt mixtures incorporating these solid wastes. To this end, two types of aggregates (SS and diabase), three kinds of SS content and multiple freeze–thaw cycles were considered and three kinds of adhesion assessment methods: pull-out test and surface free energy (SFE) method, and freeze–thaw splitting test were performed. Three corresponding adhesion evaluation indicators like adhesion strength, SFE characteristics, and tensile strength ratio were obtained and six energy parameters were introduced to characterize moisture susceptibility of asphalt mixture. To explore the relations between the SFE parameters and the adhesion evaluation indicators, a grey correlation analysis method was adopted. Asphalt mixtures with high consumption of SS obtained a better moisture resistance because SS has a superior adhesion strength and higher SFE components than diabase aggregate. Stripping energy increase was found to be the main failure mode of the asphalt rubber-SS aggregate system. SFE method provides a comprehensive and accurate evaluation of adhesion property of loose asphalt rubber–SS aggregate system and moisture stability of compacted asphalt mixtures.

The sorption of water and methanol droplets on Teflon films, as well as on various representative classes of hydrocarbon-based proton exchange membranes (PEMs) was investigated using contact angle measurement (drop shape method) during wetting under ambient open-air conditions. Teflon films exhibited constant hydrophobic surfaces when contacted with water, but a significant sorption of methanol. The PEMs showed slow sorption of water, and a significant sorption of methanol. The differences in sorption of water and methanol on Teflon and PEMs arose from the match/compatibility in the surface free energies as well as polarities between a liquid and a membrane. The significant discrepancies in surface free energies and polarities between water (72.0 mJ m(-2) and 70.1%, respectively) and Teflon film (14.0 mJ m(-2) and 4.9%, respectively) lead to a highly hydrophobic surface and no discernible sorption of water on Teflon films, while the relative similarity or minor discrepancy in surface free energies and polarities between methanol (22.5 mJ m(-2) and 17.0%, respectively) and Teflon film (14.0 mJ m(-2) and 4.9%, respectively) results in a significant sorption of methanol on Teflon. The surface free energies of PEMs were calculated using the harmonic-mean approach, based on contact angle measurements using both water and diiodomethane as probes. The results show that PEMs have initial surface free energies ranging from 44.1 to 54.0 mJ m(-2) along with polarities in the range of 20.8 to 29.1%, for a selection of typical sulfonated polymers. The surface free energies of ionomers were principally contributed to by the nonpolar component, but the presence of polar groups in the polymer increased the polar component, leading to an increase in surface free energy. Of the PEMs investigated, sulfonated poly(aryl ether ether nitrile) has a higher surface energy than those of other ionomers with similar sulfonate contents. The compatibility between water/methanol and PEMs was investigated on the aspect of surface free energies. The present study provides a plausible strategy to prescreen potential PEMs and optimize membrane electrode assembly (MEA) fabrication.

Attributing the resistance against simulated tree gum of an acrylic/melamine film loaded with an active silicone additive to its surface free energy

Modification of food contacting surfaces by plasma polymerisation technique. Part I: Determination of hydrophilicity, hydrophobicity and surface free energy by contact angle method

Grey correlation analyses were carried out to determine which chemical components and chemical elements of asphalt binders are most related to surface free energy (SFE) measurements of asphalt binders. The total, dispersive, and polar SFE values were calculated for 23 Strategic Highway Research Program (SHRP) asphalt binders based on contact angle measurements by the sessile drop method and the chemical composition data of the 23 binders was obtained from previously published information. During the Grey correlation analysis, it was found that polar aromatics content has the largest effect on the total SFE and dispersion component of SFE, whereas saturates made the largest contribution to the polar component of SFE. Carbon (C) and hydrogen (H) made the largest contribution to the total, dispersion, and polar SFE; vanadium (V) content has the smallest effect on the total surface free energy, including its dispersion and polar parts.

The objectives of this study were to investigate the improvement on flowability of a model cohesive powder using two different types of fumed silica mixed by the dry coating method “mechanofusion” and to explore the relationship between flowability and surface free energy and/or wettability. The first aim was to find the optimum conditions for improving the flowability of a model cohesive powder, glass microspheres (DMV ~ 3.5 µm), by mechanofusion with fumed silica. Conventional blending using tumbling was done as a comparison. Mechanofusion was conducted at three different speeds 1500, 3000 and 4500 rpm and at three concentrations of hydrophobic Aerosil®R972 (1%, 3% and 5% w/w) for 10 minutes, while conventional blending was performed at 72 rpm for 30 minutes. It was revealed that the optimum concentration to improve flowability was 1% w/w Aerosil®R972 for all processes utilized. Increasing the concentration of the fumed silica decreased the flowability at all speeds. This indicates the enhancement of flowability of this model cohesive powder depends on the concentration of guest particles. The influence of different speeds to the flowability was observed upon the increasing concentration of Aerosil®R972 at 3% and 5% w/w. Mechanofusion was found to be a more effective mixing method compared to tumbling mixing presumably due to the higher energy applied that can de-agglomerate the cohesive microspheres. The second aim of this thesis was to determine the mechanism of action of the fumed silica in improving cohesive powder flow and to investigate the relationship between flowability and surface free energy and/or wettability. Hydrophilic fumed silica Cab-o-sil®M-5, which has the same particles size as Aerosil®R972, was used as a comparison. 1% w/w Cab-o-sil®M-5 failed to improve the flow of particles, whereas the same concentration of Aerosil®R972 did. Powder wettability and surface free energy were derived from contact angle measurements of uncoated and coated particles. The capillary rise technique was used to measure powder contact angles. The water contact angle increased when the glass microspheres were coated with hydrophobic Aerosil®R972, whereas it decreased when coated with hydrophilic Cab-o-sil®M-5. However, the 1-bromonaphthalene contact angle increased after coating with both types of fumed silica. The contact angle data was used to calculate the surface free energy of uncoated and coated particles. A decrease in dispersive and polar components of surface free energy was found in particles coated with hydrophobic fumed silica, while the surface free energy of particles coated with hydrophilic fumed silica reached the highest value. Particles with higher surface free energies had poorer flow than particles with lower surface free energies. Similarly, particles with a water contact angle less than 90° had lower flowability than particles with a water contact angle higher than 90°. Therefore, this study found that the improvement of flowability of micronized cohesive particles can be achieved by mechanofusion provided the chosen guest particle has relatively low surface free energy and/or is hydrophobic. The outcomes of this thesis present an enhanced better understanding of improving the flowability of a cohesive powder using fumed silica. These findings may have future value for the development of improved solid formulation of pharmaceutical preparations with the active pharmaceutical ingredients (APIs) in micron size.

Improvement in surface properties of Si wafer by mechanical surface treatment

Hybrid hydrogels are materials that incorporate features from multicomponent systems of polymers, significantly improving their functionality and making them ideal for biomedical applications. Both natural and synthetic polymers are utilized, further enhancing their functionality. The combination of polyaniline (PANI), chitosan (CS), and acrylic acid (AA) can result in a multifunctional hybrid hydrogel that is antibacterial, hydrophilic, and salt-sensitive. A multifunctional PANI-CS-AA with varying PANI weight ratio was synthesized in this study. In addition, improving the surface of the multifunctional hydrogels by atmospheric pressure plasma (APP) treatment was also investigated. During APP treatment, the production of reactive species (e.g., OH and N2 radicals) responsible for the functionalization of the hydrogel surface was confirmed through optical emission spectroscopy. The integration of three polymer components in the synthesized hydrogels was confirmed through the presence of their mid-FTIR spectral characteristics, particularly in the AA and CS C=O, PANI quinonoid and benzenoid units, AA COO−, and the PANI aromatic and C—H vibration regions. Moreover, the hybrid hydrogels with incorporated PANI and APP treatment improved their wettability and surface free energy (SFE) characteristics. The hybrid hydrogels with 0.25 wt. % PANI and exposed to 2 min air plasma yielded the highest hydrophilicity and total SFE with values 41.27° ± 2.15° and 135.68 ± 4.72 mJ/m2, respectively. The plasma-treated 0.25PANI-2.5CS-4AA samples exhibit improved swelling response in water (Smax = 1310 ± 100; ks = 0.005) and saline media (Smax = 1280 ± 80; ks = 0.001) due to enhanced polymeric chains and affinity toward polar liquids. Synthesized hydrogels exhibited antibacterial activity, as evidenced by the zone of inhibition test. Clearing zones measured were in the range of 16–27 mm. The study developed an APP-treated tricomponent hydrogel consisting of PANI, CS, and AA that has improved hydrophilicity, salt sensitivity, and antibacterial features.

Thin films of polypropylene (PP) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. PP samples before and after the treatments are studied using contact angle measurements, surface free energy calculations and scanning electron microscopy (SEM). Distilled water (H2O), glycerol (C3H8O3) and diiodomethane (CH2I2) are used as test liquids. The contact angle measurements between test liquids and PP samples are used to determine total surface free energy using sessile drop technique. PP films show a remarkable increase in surface free energy after plasma treatment. SEM analysis of the plasma-treated PP films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.

The surface properties of ionomers based on styrene-co-acrylic acid copolymers

Novel organofunctional siloxanes from γ-methacryloxypropyltrimethoxysilane (MPTMS) were synthesized by transesterification reactions with high monohydric alcohols, branched alcohols, ether alcohols, phenol, and mandelic acid. The factors effecting the substitution ratios were determined. Copolymers of these siloxanes with methyl methacrylate (MMA) were prepared by bulk copolymerization in glass molds and their swelling, thermal, oxygen permeability, and surface free energy characteristics were investigated in order to determine the effect of the substituted group on the produced copolymer. The changes in these properties by the crosslinking of the copolymer with ethylene glycol dimethacrylate (EGDM) were also investigated. The copolymers containing branched, nonpolar, and lengthy pendant groups were found to be highly oxygen permeable possibly due to the introduction of larger free volume by these groups. The surface energy analysis showed that the main variation was found to be in γ values rather than γ values and only ether alcohol substitution increased γ values to a greater extent.

The purpose of this study was to investigate the shear bond strength (SBS) and surface free-energy (SFE) of short fiber-reinforced resin composite (SFRC), using different adhesive systems, in comparison with other composite restoratives. The resin composites used were everX Posterior (EP), Clearfil AP-X (CA), and Filtek Supreme Ultra Universal Restorative (FS). The adhesive systems used were Scotchbond Multi-Purpose (SM), Clearfil SE Bond (CS), and G-Premio Bond (GB). Resin composite was bonded to dentin, and SBS was determined after 24 h of storage in distilled water and after 10,000 thermal cycles (TCs). The SFEs of the resin composites and the adhesives were determined by measuring the contact angles of three test liquids. The SFE values and SFE characteristics were not influenced by the type of resin composite, but were influenced by the type of adhesive system. The results of this study suggest that the bonding performance and interfacial characteristics of SFRC are the same as for other composite restoratives, but that these parameters are affected by the type of adhesive system. The bonding performance of SFRC was enhanced by thermal cycling in a manner similar to that for other composite restoratives.

In modern polymer industry, there still is a room for new generations of fillers capable of enhancing the performance of composite materials. Currently, much effort is being put into a process of improving mechanical properties of elastomer materials. In this work, multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GnPs) were modified with silane, titanate, or zirconate using plasma treatment, in order to apply them as fillers for styrene/butadiene rubber. Following its modification, filler surface was analyzed: Surface free energy (SFE) was measured with tensiometry, and micromorphology and chemical composition were studied with scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS), while elemental composition and bonding were assessed with X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Low-temperature oxygen plasma activation of MWCNT fillers leads to a significant increase in the SFE polar component, with the same effect being much weaker for GnP fillers. Grafting silanes, zirconates, and titanates on activated filler surface results in a decrease in SFE polar component—surface oxygen-containing active groups react with silane/zirconate/titanate molecules. Fillers modified in this way exhibit different micromorphology and surface chemical composition what is revealed with the SEM–EDS, ToF-SIMS, and XPS techniques. As the ultimate step, either MWCNT or GnP rubber nanocomposites were manufactured using the modified fillers with their mechanical properties and cross-link density being studied. Filler modification resulted in substantial changes both in composite performance, and in its cross-linking density. In the case of modified filler containing composites, improved tensile strength and elongation at break were observed.

This study investigates the influence of the surface free energy (SFE) on the adhesion behaviour between wheat dough and bakery-relevant food processing surfaces. In doing so, the contact time and production-related changes of the adhesive and the adherend were taken into account. The adhesion measurements were conducted by means of previously developed methods (modified Chen/Hoseney, contact time measuring cell), whereby the force required for separating the dough from the surface after processing-relevant contact times was determined applying a texture analyzer. The SFE was determined by contact angle measurements. The SFE values for the examined materials are ranged between 5.5 ± 0.81 and 42.7 ± 0.88 mN/m. A strong linear correlation between the SFE of the bakery surfaces and their adhesion to dough could be determined after a certain contact time (≥ 1 min) (r = + 0.96 for surfaces with Sa > 20 μm; r = + 0.94 for surfaces with Sa < 20 μm). Bakery surfaces with energy values σsolid surface, total > 30 mN/m including a polar content indicated a strong interaction with wheat dough, which was confirmed by high adhesion values. Production-related changes to the processing surfaces showed a great impact on the adhesion behaviour: e.g. the abrasion of proofing cloths caused a higher amount of protruding fibres, which operate as a separating layer, resulting in a decrease of dough adhesion even after long contact times. The results in this study emphasize the importance of the SFE in the development of processing surfaces for the baking industry.