Mustafa Erdem Ureyen

Investigations on advance effects of boron-containing compounds have gained attention the last decade. This study was carried out to investigate the effect of hexagonal boron nitride nanoparticles (BNNPs) on Bovine Coronavirus (BCoV) and Staphylococcus aureus (S. aureus) by different methods. First, biological effects of different BNNPs concentrations lower than 0.5 mg/mL examined on HRT-18 (Human Rectal Tumor) for 5 days. Different concentrations of hBN mixed with BCoV in liquid, on membrane or directly on cells and examined for differences of titers or replications. And also Bacterial Filtration Efficiency (BFE) test of hBN powders coated on polypropylene fabric by spray method was applied against S. aureus. The compound was found slightly toxic on the HRT-18 cell line by live cell counting, while no remarkable morphological difference was observed. BNNPs treatment with 0.025 or 0.3mg/mL concentrations did not reduce the infective titer and create no inhibitory effect on in vitro replication. Stability of virus titer after treatment of BNNPs coated fabric also indicated no antiviral efficiency. But hBN applied fabric formed a barrier of ≥90.3%, while non hBN applied fabric formed ≥64.6% barrier. The present study demonstrate that, BNNPs alone is not a good candidate for disinfectant or drug for BCoVs, while it could be valuable to use as coated fabric in the areas needing easy sanitation especially for S. aureus.

Polyvinyl chloride (PVC) is used as an insulator in cable production. In order to enhance its thermal stability and flame retardant properties various chemicals have been added to PVC. In this study, hexagonal boron nitride (BN) and colemanite (C) at different concentrations were added to PVC to prepare composites by melt compounding method. The effect of formulation on the properties of PVC composites were observed. The thermal stability of PVC composites was determined by using a PVC Thermomat device. LOI (Limiting Oxygen Index) tests were performed to examine combustion characteristics. The mechanical properties of the composites were conducted by tensile tests. BN and C had a positive effect on the thermal stability of PVC. PVC remained stable for 3.74 hours at 210°C. Addition of BN and C (1 wt.% of the amount stabilizer) increased stability time to 4.16 hours, and 5.50 hours, respectively. The composite in which BN and C were used together remained stable for 5.74 hours. LOI value of BN and C added composite did not change noticeably, compared to neat PVC. The mechanical properties of composites remained within acceptable limits for being used in cable production. In brief, addition of BN or C to PVC is an effective technique to produce cables with improved properties for various applications.

In this study, an N‐alkoxy‐hindered amine‐based UV stabilizing agent (NOR‐116) and nanosized silica particles (Aerosil R‐972) were combined with a cyclic phosphonate based‐flame retardant (FR; PCO‐900) and incorporated into polypropylene via melt extrusion in a microcompounder. In order to stimulate the conditions in the favor of further processing such as fiber spinning, the content of additives in polypropylene was kept low (up to 6.5 wt %). The effects of the PCO‐900, alone and in combination with NOR‐116 and Aerosil‐R972, on the flammability and thermal stability of polypropylene were evaluated by limit oxygen index (LOI) tests, cone calorimetry, and thermogravimetric analysis. The proposed system with 3.5 wt % PCO‐900/1.5 wt % NOR‐116/1 wt % Aerosil‐R972 decreased the heat release, increased the LOI and thermo‐oxidative stability, and, thus, improved the fire resistance of polypropylene. The possible mode of FR activity was also discussed based on the analysis. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48308.

Zinc borate (ZnB) has been used as a flame retardant, a smoke suppressant, and an antitracking agent in several applications. It may show synergistic effects with antimony oxide and metal hydroxides in fire retardant systems. In this work, the effect of ZnB on the flame retardancy of PET (poly(ethylene terephthalate)) woven fabrics was investigated. In order to provide the homogenous application of ZnB to the fabrics, the particle size of ZnB powders was reduced from 9 μm to submicron scale by wet-milling with zirconia balls followed by high shear fluid processing. ZnB dispersion was mixed with low-formaldehyde melamine resin based cross-linking agent and it was applied to PET fabrics by pad dry cure method. ZnB dispersion was then added in different ratios to alkyl phosphonate and organophosphorus compound based commercial flame retardant finishing agents and applied to the fabrics. The effect of zinc borate with phosphorus based flame retardant (FR) finishing agents was examined by cone calorimetry under a heat flux of 35 kW/m², vertical flame test, and limit oxygen index. Thermogravimetric analysis was performed up to 800°C under N₂flow. Test results show that zinc borate can be combined with the organophosphorus based commercial FR finishing agents. Zinc borate could not improve the flammability properties of PET fabrics significantly but decreased mean CO, total smoke release, and total smoke production values.

Rigid polyurethane foam (RPUF) composites with triphenyl phosphate (TPhP), aluminum trihydrate (ATH), and zinc borate (ZnB) alone, as well as their binary blends, were prepared via a one‐shot process. The amount of flame retardant (FR) or FR blend was varied from 10 to 50% by polyol weight percentage, and the weight fraction of the blends was also fixed at 40%. The effects of additives on thermal insulation, mechanical, and flame retardancy properties of the composites were investigated. Thermal conductivity of the neat foam (RPUF) decreased from 22.53 to 21.04–21.58 mW m⁻¹K⁻¹. The compressive strength of foams displayed an increase with increasing the amount of TPhP, ATH, and ZnB till 40% by weight. The limited oxygen index values of all foams increased and the flame spread rates of all foams significantly decreased. It was also observed that the flame was self‐extinguished in some cases. The cone calorimeter test results indicated that the FR additives improved the flame retardancy of the RPUF. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2020,137, 47611.

The effects of sepiolite on fire behavior of ammonium polyphosphate-based intumescent flame retardant (IFR)/polypropylene (PP) were investigated. The disaggregation of sepiolite bundles has been provided by wet-milling as the zeta potential value decreased from −9.6 to −31.3 mV. PP and additives were compounded by a twin-screw extruder and molded by injection. A total additive content of 20 wt% in PP and various proportions of sepiolite (1.0–10.0 wt%) in flame retardant (FR) formulation were studied. The flammability of the samples was measured by limit oxygen index (LOI) test and cone calorimetry. The LOI of neat PP (19%) was increased to 32.2% when sepiolite and IFR were used. The peak heat release rate of neat PP (1566.4 kW/m ² ) was also significantly reduced (94.7 kW/m ² ) when sepiolite was added with IFR. Thermal analyses results showed that, at higher temperature (700°C), IFR and sepiolite increased the char residue (9 wt%) compared to neat PP (0 wt%).