PROTECTIVE WOOD TREATMENT WITH AN OLIGOMER CONTAINING STYRENE UNITS

Currently, much attention is paid to the protective treatment of wood materials. This allows you to protect wood from adverse factors and extend the service life of products based on it. At the same time, not a little, an important criterion is the ratio of the price of the protective composition and its quality. The article discusses the possibility of using an oligomer for the protective treatment of natural wood, obtained on the basis of by-products of the production of polybutadiene and modified with secondary polystyrene. Considering the fact that this waste has not found its application, its use makes it possible to obtain not only valuable and affordable compositions based on it, but also to solve a number of environmental problems. For the modification, an oligomer with a bound styrene content of about 50% was used. The process was carried out at 200°C in the presence of a desiccant. At high temperatures and in the presence of atmospheric oxygen, destruction of both oligomer and secondary polystyrene occurs. The resulting destruction products interact with each other with the formation of new macromolecules containing an increased amount of styrene groups and the appearance of functional groups containing oxygen in the polymer chains. Protective treatment of natural wood with the obtained impregnating compounds allows to reduce water absorption and swelling of birch samples. This treatment allows you to extend the life of wood products.

Properties of styrene-ethylene-butylene styrene block copolymer/exfoliated graphite nanoplatelets nanocomposites

Three different types of styrene-ethylene-butylene-styrene block copolymer (SEBS) with varying ratios of styrene and rubber were melt-compounded with exfoliated graphite nanoplatelets at different loadings. The morphological, thermal, and mechanical properties of the nanocomposites were studied and compared. Morphological observation under SEM and AFM found that the xGnPs were dispersed at the sub-micron level throughout the SEBS matrix. Good interfacial adhesion between the xGnPs and the matrix was also observed. However, the behavior of dispersion was dependent on the styrene/rubber content. SEBS with higher styrene content showed better dispersion and strong interfacial adhesion between the xGnPs and SEBS matrix. These results contributed to the enhancement of the tensile strength of the nanocomposites. Low styrene content behaved like rubber that resulted in low tensile strength but higher elongation compared to SEBS of different amounts of styrene. The XRD patterns indicated that the melt compounding process did not change the d-spacing of xGnPs in all types of SEBS. From the thermal analysis, there was no change in the glass transition of the polymer and no improvement in the thermal stability of the nanocomposites.

Form-Stable Phase Change Materials Based on SEBS and Paraffin: Influence of Molecular Parameters of Styrene-b-(Ethylene-co-Butylene)-b-Styrene on Shape Stability and Retention Behavior

In this work, the influence of molecular parameters of styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) triblock copolymer as matrix material in form-stable phase change material (FSPCM) on the thermo-mechanical properties and leakage behavior are studied. Various SEBS grades differing in their molecular weight, styrene content, and ethylene/butylene ratio are used as supporting matrix in composites with 90 wt.% paraffin. Thermo-mechanical properties are determined by rheological measurements. The results show phase transitions temperatures from solid to hard gel, hard gel to soft gel, and soft gel to gel fluid. Paraffin leakage in FSPCM is analyzed by mass loss over time in an oven at 60 °C. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are applied to determine the thermal energy storage capacity. Finally, the molecular weight and the styrene content are combined to the molecular weight of styrene block which is identified as the authoritative parameter for the thermo-mechanical properties of the SEBS/PCM composite.

Copolymerization of Styrene and Pentadecylphenylmethacrylate (PDPMA): Synthesis, Characterization, Thermomechanical and Adhesion Properties

The copolymerization of styrene (St) with a bioderived monomer, pentadecylphenyl methacrylate (PDPMA), via atom transfer radical polymerization (ATRP) was studied in this work. The copolymerization reactivity ratio was calculated using the composition data obtained from 1H NMR spectroscopy, applying Kelen-Tudos and Finemann-Ross methods. The reactivity ratio of styrene (r1 = 0.93) and PDPMA (r2 = 0.05) suggested random copolymerization of the two monomers with alternation. The copolymerization conversion increased with increasing PDPMA concentration of the feed, upto 70 wt % PDPMA, but decreased thereafter. The molecular weight determined by gel permeation chromatography was lower than the theoretical values and the polydispersity increased from 1.32 to 2.19, with increasing PDPMA content in the feed. The influence of styrene content on the glass transition and thermal decomposition behavior of the copolymers was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis, respectively. Morphological characterization by transmission electron microscopy (TEM) revealed a phase separated soft core-hard shell type structure. The complex viscosity and adhesion properties like peel strength and lap shear strength of the copolymer on different substrates increased with increasing styrene content.