Recovered carbon black; material characterization and in-rubber performance:Sustainable future of tire manufacturing

Carbon black is widely used as a reinforcing filler in tire industry.This project aims to recover high quality carbon black from used tires using a novel pyrolysis process. The influence of process temperature on the recovered carbon black(RCB) properties was studied. Pyrolysis was carried out using passenger car tire(PCT) feedstock at temperatures of 500°C(PCT500) and 550°C(PCT550). Material properties and in-rubber performance were compared to a reference carbonblack commonly used in tires

Towards more homogeneous character in 3D printed photopolymers by the addition of nanofillers

The performance of 3D printed materials differs from that of fully cured polymer materials because of the presence of interfacial areas between consecutively joined layers. These interfaces result in an inhomogeneous character of the printed objects and is frequently reported as their main cause of failures. We noted that the presence of nanosilica particles strengthens the 3D printed layers of the polymer matrix by inducing its additional crosslinking. A model resin composed of poly (ethylene glycol) diacrylate (PEGDA) and nanosilica (Aerosil R972) is used for vat photopolymer 3D printing. Evolution of the interface properties at different nanosilica loadings is tracked by mapping its surface stiffness (Young's modulus mapping) using quantitative Atomic Force Microscopy (AFM). Our research demonstrates that incorporating 6% w/v nanosilica in the polyPEGDA matrix unifies its mechanical properties within the layer, leading to a substantial reduction of microscopic inhomogeneity in the final 3D printed materials.</p

Water-soluble polyphosphonate-based bottlebrush copolymers via aqueous ring-opening metathesis polymerization

Ring-opening metathesis polymerization (ROMP) is a versatile method for synthesizing complex macromolecules from various functional monomers. In this work, we report the synthesis of water-soluble and degradable bottlebrush polymers, based on polyphosphoesters (PPEs) via ROMP. First, PPE-macromonomers were synthesized via organocatalytic anionic ring-opening polymerization of 2-ethyl-2-oxo-1,3,2-dioxaphospholane using N-(hydroxyethyl)-cis-5-norbornene-exo-2,3-dicarboximide as the initiator and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the catalyst. The resulting norbornene-based macromonomers had degrees of polymerization (DPn) ranging from 25 to 243 and narrow molar mass dispersity (Đ ≤ 1.10). Subsequently, these macromonomers were used in ROMP with the Grubbs 3rd-generation bispyridyl complex (Ru-G3) to produce a library of well-defined bottlebrush polymers. The ROMP was carried out either in dioxane or in aqueous conditions, resulting in well-defined and water-soluble bottlebrush PPEs. Furthermore, a two-step protocol was employed to synthesize double hydrophilic diblock bottlebrush copolymers via ROMP in water at neutral pH-values. This general protocol enabled the direct combination of PPEs with ROMP to synthesize well-defined bottlebrush polymers and block copolymers in water. Degradation of the PPE side chains was proven resulting in low molar mass degradation products only. The biocompatible and biodegradable nature of PPEs makes this pathway promising for designing novel biomedical drug carriers or viscosity modifiers, as well as many other potential applications.</p

Acceleration of Biodegradation Using Polymer Blends and Composites

Biobased and biodegradable polymers are used in bioplastics as blends or composites of various materials to tune their physical properties but also influence their stability with respect to biodegradation. Biodegradable polymers are often not as biodegradable as they are claimed to be, especially due to different degradation conditions in soil, water, compost, or in vivo. Mixing such polymers with faster degrading polymers (blends) or fillers (composites) is a powerful strategy to adjust degradation rates. This review selects representative examples of bioplastic blends and composites in applications, such as tissue engineering, agriculture, or packaging, with a focus on controlling/accelerating the biodegradation rates. It also focuses on strategies such as hydrolysis enhancement, attraction of microbes for microbial degradation, pore forming fillers, or increase of phase separation in polymer mixtures. A basis for the prevention of microplastic formation or unwanted side effects with too slow degradation rates of biodegradable polymers is set.</p

Copolymerizing Lignin for Tuned Properties of 3D-Printed PEG-Based Photopolymers

The global emphasis on environmental conservation has sparked the exploration for alternative materials to replace nonrenewable petroleum-based products. With abundant lignocellulosic biomass, there is a growing focus on designing biobased polymers with enhanced properties. In this work, we prepared lignin-containing copolymer macrostructures by 3D printing of poly(ethylene glycol) diacrylate (PEGDA) and biobased methacrylated Kraft lignin. Studied lignin loading is up to 10 w/v %. Liquid crystal display stereolithography was used to 3D print models of varying complexities and sizes. We demonstrate that methacrylated lignin can be thoroughly dissolved within the polyPEGDA matrix. This enables the adjustment of light shielding, mechanical performance, and antioxidant activity in the final high-resolution 3D-printed materials. Adding just 1 w/v % of the lignin-based component to the translucent (visible light) and brittle polyPEGDA reduces the transmittance of visible light to only 30% (at 550 nm). Additionally, it improves the elongation at break by a factor of 1.5 when compared with pure PEGDA-based resins. Moreover, the antioxidant properties of lignin further enhance the materials, resulting in approximately 40% antioxidant activity. The 3D-printed materials under study can then be considered as structures that block light and inhibit oxygen, making them suitable for applications in biotechnology.</p

AFM monitoring of the cut surface of a segmented polyurethane unveils a microtome-engraving induced growth process of oriented hard domains

We report on nanoscale order-disorder transitions of hard segments and their domains composed of 4,4′-methylenebis(phenyl isocyanate) - 1,4-butanediol (MDI-BD), in polycaprolactone-based (Mn = 2000 g/mol) polyurethanes (PCL-PUs), when the free surface is pre-oriented by cryo-microtoming of the material. Morphological variations of the hard domains as a function of temperature and the anisotropy of surface morphology features are captured by employing Atomic Force Microscopy (AFM) stiffness imaging by PeakForce Quantitative Nanomechanical Mapping (PF-QNM). The AFM imaging is supported by WAXS, SAXS, FTIR, and DSC measurements. The experimental results show that hard domains initially grown at the surface break apart at elevated temperatures (65 °C) and cannot be re-grown upon cooling. They require new microtoming to repeat the growth scenario. The detailed step-by-step submicron scale observations of the surfaces serve to show importance of the influence that microtoming and the time after its completion have on surface morphology, and that these shall be considered when studying polymer materials microscopically.</p

Magnetosomes - Bacterial Magnetic Nanoparticles

The magnetic properties, magneto-optical effects and hyperthermia effect were studied in solution of magnetosomes extracted from cultivated bacteria Magnetospirillum sp. AMB-1. The properties of magnetosomes were changed using different conditions during synthesis and by modification of particles after synthesis by using sonication and ultracentrifugation methods. It was shown that adding a higher amount of Wolfe's vitamin solution (WVS) or ferric quinate (FQ) cause increase of the mean diameter from 47 nm (normal condition) up to 52 nm and 58 nm respectively. Hyperthermic measurements were performed for three types of magnetosome samples: (I) M - not influenced by separation method (long - chains magnetosomes), (II) UM - after centrifugation procedure, and (III) SM - after centrifugation procedure including sonication. The Specific Absorption Rate (SAR) decreased depending on chains shortening and decrease in hysteresis too. The SAR values were 1083, 934 or 463 W/g for the sample M, UM and SM, respectively

Effect of the Chain Length and Temperature on the Adhesive Properties of Alkanethiol Self-Assembled Monolayers

Stable and hydrophobic self-assembled monolayers of alkanethiols are promising materials for use as lubricants in microdevices and nanodevices. We applied high-rate dynamic force spectroscopy measurements to study in detail the influence of the chain length and temperature on the adhesion between methyl-terminated thiol monolayers and a silicon nitride tip. We used the Johnson-Kendall-Roberts model to calculate the number of molecules in adhesive contact and then the Dudko-Hummer-Szabo model to extract the information about the position and the height of the activation barrier per single molecule. Both parameters were determined and analyzed in the temperature range from 25 to 65 °C for three thiols: 1-decanethiol (measured previously), 1-tetradecanethiol, and 1-hexadecanethiol. We associate the increase of the activation barrier parameters versus the chain length with lower stiffness of longer molecules and higher effectiveness of adhesive bond formation. However, we relate the thermal changes of the parameters rather to rearrangements of molecules than to the direct influence of temperature on the adhesive bonds

Sialon and Alumina Modified UV-Curable Coatings with Improved Mechanical Properties and Hydrophobicity

This article describes the modification of UV-curable coatings with silicon aluminum oxynitride (Sialon) and aluminum oxide (Alu C), which improve the hydrophobicity of the coating surface and the scratch hardness. The contact angle is greater due to surface roughness being enhanced with inorganic fillers. Improved scratch resistance results from the formation of a sliding layer triggered by the diffusion of Sialon or alumina on the coating surface. One can observed an increase in the surface hydrophobicity as well as in the scratch hardness (up to 100%) when small amounts (5 wt.%) of the inorganic compounds are added. Imaging microscopies, i.e., SEM, OM, and AFM (with nanoscopic Young’s modulus determination), revealed the good distribution of both types of fillers in the studied matrix