Anatoly Popov

Modification of isotactic polypropylene by additives of low-density polyethylene and powdered cellulose

The effect of addition of low-density polyethylene and/or cellulose powder on the structure of isotactic polypropylene was investigated using methods of wide-angle X-ray scattering and differential scanning calorimetry. The effect of polyethylene and cellulose on the structure and properties of the crystalline phase of isotactic polypropylene was demonstrated.

Influence of Filler Particle Size on Physical Properties and Biodegradation of Biocomposites Based on Low-Density Polyethylene and Lignocellulosic Fillers

This study examined biocomposites based on low-density polyethylene (LDPE) and lignocellulosic fillers [wood flour (WF) and oil flax straw (FS)] selecting four size fractions of each lignocellulosic material as fillers for the composites. The primary aim was to evaluate the influence of fraction size on the composites’ basic properties; to accomplish this, the composites’ mechanical properties, thermal oxidation, thermophysical characteristics, and water absorption capacity were examined. Then microphotographs of the samples were created and length-to-diameter (L/D) ratioxa0of the fillers was calculated, finding that the L/D ratio increased with increasing particle size. The particle size influenced the oxidative degradation and water absorption processes in composites with oil flax but not in those with WF. Biodegradation tests performed on the recovered soil found that the loss of mass in composites based on LDPE and FS was higher than in the same composites with WF. Moreover, at the initial stage of composting, the biodegradation rate correlated with the size of filler particles (i.e., the larger the particles, the higher the degradation rate of the biocomposite).

Structural changes in the low-density polyethylene/natural rubber composites in the aqueous and soil media

The novel biodegradable materials based on polyethylene with different content of natural rubber have been developed. In this paper the regularities of changes in structure and properties of the composites under the influence of biological and non-biological factors have been investigated. High levels of biodegradability and satisfied mechanical properties of biocomposites, as well as the significant modification of the polyethylene crystalline phase in the composites affected by moisture and environmental factors have been determined.

Morphology, thermal behaviour and dynamic properties of the blends based on isotactic polypropylene and low-density polyethylene

The regularities of formation of the blend structure based on isotactic polypropylene (iPP) and low-density polyethylene (LDPE) in a wide range of compositions are investigated. The processes of melting and crystallization, as well as the thermal properties of these blends are examined by differential scanning calorimetry. The structure and molecular mobility in the amorphous regions are studied by electron paramagnetic resonance spectroscopy (paramagnetic probe method). The mutual influence of both mixture components on the development of the composition morphology is found. Also three ranges of the blend composition (5–30; 30–70; 70–95xa0wt% of iPP) characterized by different structures and properties of crystalline and amorphous phases are determined. The partial compatibility in the amorphous regions of iPP and LDPE providing the interface layer formation is observed for the blends containing 30–95xa0wt% of iPP. In case of the content of iPP in the blend is less than 30xa0wt%, the abnormal process of iPP crystallization is determined. As a result the non-equilibrium molecular structure of the iPP/LDPE composition is formed.

Mechanical properties of ethylene-octene copolymer (EOC) - lignocellulosic fillers biocomposites in dependence to filler content

The mechanical properties of biocomposites based on ethylene-octene copolymer were studied. The aim of present work was to investigate the mechanical properties of composites based on ethylene-octene copolymer (EOC) in dependence to type of the filler, filler content and trade mark of EOC. Addition of fillers (wood flour or seed flax straw) decreases elongation at break and decreases unsignificantly tensile strenght of examined copolymers. Particles of filler increase the toughness of polymer chain, which leads to decline of elongation at break. Biocomposites with wood flour had higher tensile strength and elongation at break than the composites with flax straw.

Novel technology of butyl rubber chlorination and investigation of chlorinated modifier content influence on vulcanizing characteristics of pure-gum compound

The paper is devoted to the novel solution for the technology of chlorination butyl rubber – mechanochemical halide modification, as a more efficient way to obtain halogenated elastomers with a wide range of halogen content (from 3 to 15 %). The vulcanizing characteristics of elastomeric compounds based on the chlorinated butyl rubber as well as the production conditions of vulcanization process have been studied by the methods of differential scanning calorimetry and dynamic mechanical rheometry. The performed investigation revealed the optimum content of the vulcanizing agent (6 wt%) and accelerator (2 wt%) for chlorinated butyl rubbers compositions. The preferable vulcanization temperature of 150±5°C for rubbers under investigation regardless of chlorine content in a sample has been determined. The effectiveness of the process of vulcanization studies by combination of differential scanning calorimetry and dynamic mechanical rheometry methods with the purpose of comprehensive assessment of the rubber c...

Water absorption and biodegradation kinetics of highly filled EOC–FS biocomposites

The paper analyzes the water absorption and biodegradation kinetics in highly filled biocomposites based on ethylene-octene copolymer (EOC) and oil flax straw (FS). It is shown that adding the filler to EOC increases the water absorption from 0 to 22%. The tendency can be explained both by the low interfacial adhesion of EOC to FS and by the hydrophilic nature of the filler. According to biodegradation tests (10 months), the mass of pure EOC remains unchanged, suggesting that it fails to biodegrade in the environment. Increasing the filler content increases the weight loss of the composites and the degree of microbiological contamination (fungi filaments, bacteria) as evidenced by optical microscopy.

Degradation kinetics of ethylene-octene copolymer/wood flour biocomposites in dependence to filler content

This article is focused on thermal oxidative degradation and biodegradation in soil of biocomposites based on ethylene-octene copolymer (EOC), filled by wood flour (from 30 to 70% wt.), in dependence to the filler content. The study of oxidative degradation of composites was carried out at two temperatures (80 and 130°C respectively). The induction period and the rates of oxidation were determined. It was concluded that as filler content raises, the induction period increases. It can be explained by the higher specific area of composites in comparison with pure EOC. However, high filled composites (60 and 70 % of the filler) are oxidized with a huge induction period because polyphenols in the filler inhibit the oxidation process. Biodegradation test under laboratory conditions was carried out to investigate the biodegradability of the material. Composites with lower filler content have lower weight loss rate. Small particles are capsulated by polymer and are isolated from moisture and microorganisms. On the other hand, at a high filling of the composite small particles stick together and act as large ones. Such filler agglomerates are connected with each other and allow microorganisms to penetrate into the composite. It was concluded as filler content raises the mass loss increases.

Effect of biobased fillers nature on biodeterioration of hybrid polyethylene composites by mold fungi

The paper is devoted to investigation of deterioration of natural fillers and polyethylene composites on their basis (polyethylene/filler=70/30) due to the action of mold fungi. The fillers chemical composition, dimensional parameters and biodegradability have been analyzed as factors exert a considerable impact on composite materials biodeterioration. It has been found that the principal factor determining the biodeterioration of polyethylene/filler composites by mold fungi is chemical composition of a filler and, in turn, its biodegradability. The excess of holocellulose content over lignin content and high protein content in a filler are able to induce biofouling of the polymeric composite materials. The presence of soluble and easy hydrolysed fraction in a filler increases its availability in a polymeric matrix. According to the study results, most effective natural fillers as additives stimulating polyethylene composites biodegradability are milled straw of seed flax and hydrolyzed keratin of birds feather.

Chemical interaction of polyethylene matrix with vegetable fillers in biocomposites

The paper studies the diffusion of low molecular weight components from vegetable fillers into polyethylene matrix during the preparation of biocomposites. In order to identify the diffusible substances a model experiment used where the hexadecane acted as a model of polyethylene. It was determined that polyphenolic compounds and chlorophyll penetrate from vegetable fillers to hexadecane to the maximum extent. There was found a correlation between the amount of polyphenolic compounds diffusible from the fillers to hexadecane and thermal oxidation kinetics of real biocomposites based on polyethylene and vegetable fillers. Thus, it has been assumed the diffusion of polyphenols and chlorophyll from vegetable fillers into polyethylene matrix during the preparation of biocomposites.