E. V. Prut

Synthesis and investigation of polyethylene blends with natural polysaccharides and their derivatives

Powder blends of LDPE with cellulose, ethyl cellulose, starch, chitin, and chitosan have been prepared under shear deformation in a rotor disperser at different initial-component ratios. The composition of powder fractions is identical to the original composition of the blends. The studied polymer blends demonstrate high mechanical characteristics. X-ray diffraction analysis and DSC studies show that the blending of LDPE with polysaccharides under shear deformations results in changes in the polymer structure and leads to a decrease of their degree of crystallinity. The maximum intensity of mold fungi growth is observed in starch-LDPE (50: 50, wt/wt) and chitin-LDPE (50: 50, wt/wt) blends.

Structure and prolonged transport in a biodegradable poly(R-3-hydroxybutyrate)-drug system

In order to create new biodegradable systems for the targeted transport of drugs, poly(3-hydroxy-butyrate) films containing the antibiotic rifampicin in an amount of 5–15 wt % as a model drug are prepared. Film surfaces are studied via scanning electron microscopy, and various structural elements (globules and fibrils) are found. Polymer samples isolated from melt or solution feature different degrees of porosity. It is shown that the kinetic profiles of rifampicin release are of an abnormal character. An analysis of the profiles shows that the release of rifampicin is controlled by the superposition of two processes: its desorption via the diffusion mechanism (the nonlinear segment) and hydrolytic degradation of poly(3-hydroxybutyrate) (the extended linear segment), which becomes well defined after completion of the diffusion stage. The diffusionkinetic model of the process is developed.

Biodegradable polymer composites based on polylactide and cellulose

Blends of polylactide with microcrystalline cellulose are obtained under high-temperature shear deformation. In order to improve plasticity and biodegradability of the system, low-molecular-mass poly(ethylene glycols) of various molecular masses are introduced into the composites. The mechanical and thermophysical properties of these composites, as well as their water and moisture absorptions, are studied. The morphology and biodegradability of the samples are investigated with the use of various physicochemical and biological methods.

Effect of Dynamic Vulcanization on the Structure and Properties of Polypropylene/Rubber Mixtures Studied by Positron Annihilation and Thermostimulated Luminescence Techniques

The structure of isotactic polypropylene (PP) and its blends with ethylene-propylene-diene terpolymer EPDM (0-100%) containing the unvulcanized and the vulcanized rubber phase were studied using positron annihilation lifetime (PAL) spectroscopy technique and thermostimulated luminescence (TSL). Cross-linking in the polymer blends is one of the effective ways to create novel materials with effective industrial properties. Meanwhile, composition of such systems is very complicated since it contains microphases of the dispersed components, cross-linked or not, elements of the cross-linking agents, which have some distribution between the blend components. This distribution, heterogeneity and also variation of elementary free volumes due to cross-linking are the points of interest in the study of polymer blend structures.

Dispersivity of rubbers in thermoplastic polymers

The main factors influencing the dispersivity of rubbers (nitrile and ethylene-propylene) in nylon 6 (PA-6) and polypropylene (PP) are investigated. On the basis of an equation, describing the influence of interfacial tension and viscosity ratio of disperse and matrix phases on the average size of dispersed phase particles, analysis of dispergation process in researched blended systems has been conducted. The limits of applicability of a given equation were established. It was shown that the best dispersivity of rubbers in the PA matrix is observed in that case when the viscosity values of initial components of a blend are close to each other.

The structure, properties, and thermal destruction of biodegradable blends of cellulose and ethylcellulose with synthetic polymers

Powder blends of low-density polyethylene with cellulose and ethylcellulose were obtained under high-temperature shear deformation conditions in a rotor disperser at various initial reagent ratios. The composition of powder fractions was shown to be identical to the initial blend composition, which was evidence that the compositions obtained were homogeneous. Comparative studies of the structure of the initial and produced powder blends and mechanical characteristics of films obtained from them were determined by the X-ray method. Thermogravimetric analysis was used to study thermal destruction of individual polymers and their compositions. The effective kinetic parameters were calculated and used to suggest a model of diffusion-controlled polymer decomposition. The addition of polyethylene oxide was found to increase biodegradability of compositions based on cellulose. It therefore contributed to broadening of the applicability range of materials based on them.

Study of the thermal stability of blends based on synthetic polymers and natural polysaccharides

The thermal properties of biodegradable blends based on polyethylene and natural polysaccharides prepared in an extruder were studied by thermogravimetric analysis. It was demonstrated that polymer blends are characterized by a higher thermal degradation temperature than that of the initial polysaccharides. The effects of photooxidative treatment were investigated, as well as the influence of polyethylene glycol on the thermal stability of the studied polymer blends.

Development of Novel Biodegradable Polysaccharide-Based Composites and Investigation of Their Structure and Properties

Biodegradable composites of polysaccharides (cellulose, starch, and ethylcellulose) with low-density polyethylene (LDPE) and poly(ethylene oxide) (PEO) as well as composites of two polysaccharides (cellulose–chitin, cellulose–chitosan, starch–chitin, starch–chitosan) with LDPE were produced in a rotor disperser under conditions of shear deformation. Using various physicochemical (mechanical tests, FTIR-spectroscopy) and structural (SEM) methods, the properties and structure of obtained composites were studied. The investigation of the change in the fractional composition depending on the nature of third component has shown that the introduction of PEO leads to appearance of fraction with coarse particles, while the addition of second polysaccharides results in production of finely-dispersed powders. The comparison of the mechanical properties of binary and ternary composites has showed that the presence of third component leads to change in their characteristics. The investigation of sample biodegradability by three independent methods showed that the introduction of third component leads to a significant increase in the biodegradation as compared to the binary polysaccharide–LDPE composites studied earlier.

New polymer composites based on keratin and polyethylene

New biodegradable composites based on keratin and polyethylene have been produced under shear deformation. It has been demonstrated that the introduction of keratin leads to an increase in elastic modulus and to a decrease in ultimate tensile strength and elongation at break of the compositions. Elongation at break εb depends on the keratin dispersity; the highest εb values are observed for the compositions containing the smallest keratin particles. It has been shown that the compositions are susceptible to mold fungi; i.e., they are biodegradable.

Investigation of mechanical properties, morphology, and biodegradability of compositions based on polylactide and polysaccharides

The blends of polylactide with ethyl cellulose and chitosan are obtained in a Brabender mixer under conditions of high temperature shear deformation at different initial ratios of the reagents. The investigation of physicomechanical properties of the compositions has shown that the systems have high rigidity. Polyethylene glycol (PEG) and high-molecular-weight polyolefin polydecene have been added to the compositions in order to improve their elasticity. It has turned out that polydecene scarcely affects the mechanical characteristics, while PEG leads to a noticeable increase in elongation at break. Biodegradability of the compositions is investigated by the mass loss of samples after holding in soil, fungus resistance tests, and the analysis of the film morphology by scanning electron microscopy after holding in soil. It is found that the introduction of the third component (PEG) leads to an increase in biodegradability of the compositions.