Effects of Climate on Exterior Wood Coating Performance: A Comparison of Three Industrial Coatings in a Warm-Summer Mediterranean and a Semi-Arid Climate in Oregon, USA

Wood exposed in exterior applications degrades and changes color due to weathering and fungal growth. Wood coatings can reduce the effects of weathering by reducing the damaging effects of ultraviolet light, reducing water absorption, and slowing fungal growth on the surface. Coating performance depends on the blend of resins, oils, and pigments and varies considerably among different wood species and conditions. Specific information describing expected service for different wood species and exposure conditions is not commonly available; certain combinations may work well in one climate or on one timber species, but underperform elsewhere. This study compared the performance of three industrial wood coatings on two wood species for two temperate climates under natural weathering conditions. Most of the coatings/species combinations lost their protective properties within 12 to 15 months; however, fungal growth was more prevalent at the wetter site than at the drier site for several combinations. Film-forming coatings often peeled and cracked, while penetrating coatings weathered and changed color relatively uniformly during the study. While no coating was completely effective, the results illustrate the benefits of using coatings that promote the development of natural, uniform-patinaed wood surfaces. The findings also guide coating maintenance programs for mass timber structures exposed to natural weathering conditions.

Janus particles by simplified RAFT-based emulsion polymerization process for polymer coating

We describe a simplified method to synthesize film forming polymer Janus particles by phase separation during RAFT-based free radical emulsion polymerization. Fully crosslinked snowman- or football-shaped polystyrene Janus particles (PSJPs) were first produced in a one-step batch process using amphiphilic triblock macro-RAFT copolymers as stabilizers. Such particles were in turn employed as seeds in a continuous emulsion polymerization in which a monomer mixture of methyl methacrylate (MMA) and butyl acrylate (BA) (1/1 by weight) was constantly injected into the reaction in the presence of a water soluble initiator. The added monomers wetted seed particle surface and their polymerization led to formations of 93-nm film forming single- or two-headed Janus particles. The resulted latex was successfully used to disperse and encapsulate solid calcite extender. Graphical abstract

Tribological behavior and film-forming mechanism of a polytetrafluoroethylene/polyester fabric composite

Purpose The purpose of this study is to determine the tribological behavior and wear mechanism of a polytetrafluoroethylene (PTFE)/polyester (PET) fabric composite for application as a self-lubricating liner suitable for high-speed and low-load friction conditions. Design/methodology/approach The effects of different loads and sliding speeds on the friction coefficients and wear characteristics of the composite were studied using reciprocating friction tests. Scanning electron microscopy, extended depth-of-field microscopy, and energy-dispersive X-ray spectrometry was used to analyze the worn surface morphology, wear depth and elemental content of the lubrication films, respectively. Findings The friction coefficient curves of the composites presented a long-term steady wear stage under different sliding conditions. With increasing sliding speed, the friction coefficient and wear depth of the composite slowly increased. The film-forming mechanism of the composite revealed that the PTFE/PET ply yarn on the composite surface formed complete PTFE lubrication films at the initial sliding stage. Originality/value The PTFE/PET fabric composite maintained good friction stability and high-speed adaptability, which demonstrates that the composite has broad application prospects as a highly reliable self-lubricating bearing liner with a long lifespan.

DESIGNING OF NOVEL TOPICAL IN SITU POLYMERIC FILM-FORMING SOLUTION SPRAY FORMULATION OF ANTIFUNGAL AGENT: IN VITRO ACTIVITY AND IN VIVO CHARACTERIZATION

Objective: Voriconazole (VCZ) is a broad-spectrum antifungal medication that works by inhibiting fungal Cytochrome P450, preventing fungi growth. The current study aims at developing and characterizing an antifungal in situ film-forming polymeric solution spray containing VCZ for use in topical drug delivery systems. Methods: Optimized VCZ in situ polymeric film formulation was evaluated for Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), X-ray diffractometry (XRD), Scanning electron microscope (SEM), in vitro and in vivo, ex-vivo investigation using abdominal rat skin and stability studies. The in vivo antifungal activity of the advanced in situ film was examined in albino Wistar rats. Results: The optimized batch contained 22% Eudragit RS 100 (ERS) and 4% Sorbitol. Based on FTIR, XRD, SEM, and rheological studies. Formulation ingredients of VCZ loaded topical in situ polymeric film spray were observed to be compatible and showed no evidence of precipitation, deformation, or discoloration. Diffusion test (in vitro %), and ex-vivo drug diffusion % obtained 99.22%, and 97.45% respectively. The maximum inhibition zone was measured at 13±0.07 mm. The Wistar rat was employed as an animal model for skin irritation and antifungal studies. A study of short-term stability observed no significant modifications in the physical properties. Conclusion: The findings of the optimized VCZ topical in situ polymeric film spray formulation were satisfactory, demonstrating comparable improvement in superficial antifungal treatment.

Effect of plasticizers on the properties of sugar palm nanocellulose/cinnamon essential oil reinforced starch bionanocomposite films

This work examines the effects of plasticizer type and concentration on mechanical, physical, and antibacterial characteristics of sugar palm nanocellulose/sugar palm starch (SPS)/cinnamon essential oil bionanocomposite films. In this research, the preparation of SPS films were conducted using glycerol (G), sorbitol (S), and their blend (GS) as plasticizers at ratios of 1.5, 3.0, and 4.5 wt%. The bionanocomposite films were developed by the solution casting method. Plasticizer Plasticizers were added to the SPS film-forming solutions to help overcome the fragile and brittle nature of the unplasticized SPS films. Increasing plasticizer contents resulted in an increase in film thickness and moisture contents. On the contrary, the increase in plasticizer concentrations resulted in the decrease of the densities of the plasticized films. The increase in the plasticizer content from 1.5 to 4.5% revealed less influence towards the moisture content of S-plasticised films. For glycerol and glycerol-sorbitol plasticized (G and GS) films, higher moisture content was observed compared to S-plasticised films. Various plasticizer types did not significantly modify the antibacterial activity of bionanocomposite films. The findings of this study showed significant improvement in the properties of bionanocomposite films with different types and concentrations of plasticizers and their potential for food packaging applications was enhanced.

Characterization of physical properties of bismuth-titanium coatings on 316L stainless steel

The 316 L steel is a type of stainless steel widely used in the medical industry, which in recent years has been studied for different uses in society. Being an engineering material, it is imperative to know its performance based on its physical and mechanical properties that allow identifying the response of this steel in addition to thin films as coatings. Bismuth and titanium have been recently used to improve the properties of 316 L steel, so they were used in this study. The sol-gel technique was used as the film forming method. The response of physical and mechanical properties was evaluated from the analysis of microhardness and coefficient of friction reported for the different types of steel-coating systems. Higher microhardness values were found for films with higher proportion of titanium. The coefficient of friction values is influenced by the system used, with higher values obtained for samples with a single coating layer.