I. Yu. Gorbunova

Rheokinetics of the curing of epoxy oligomer ED-20 modified with epoxy phosphazenes

The effect of epoxy phosphazene on the curing parameters of an epoxy amine composition containing epoxy phosphazene was studied via rotational viscometry. The presence of epoxy phosphazene accelerates the process and changes the pattern of polymer-network formation. As a result, the dynamics of the increase in viscosity changes.

Effect of montmorillonite on polypropylene crystallization

The effect of additions of pure and modified montmorrilonite on the polypropylene crystallization rate was studied within the framework of Avrami model. In the presence of these fillers in amounts of 2.5–5.0 wt %, both the crystallization rate and the degree of crystallinity increase, and at the content of these fillers increased to 10% and higher values these parameters decrease. Introduction of fillers enhances the mechanical properties of polypropylene, which allows the developed material to be recommended for the production of packaging film.

Features of Curing of a Diane Epoxy Oligomer Modified with Epoxyphosphazene

The results of rheokinetic, dynamic mechanical, and calorimetric investigations of the process of curing of an epoxy oligomer ED-20 blend with epoxyphosphazene by a low-molecular-weight polyamide L-20 are analyzed. It is shown that the phenomenological curing kinetics of all studied systems is characterized by the presence of two stages of the process: a second-order reaction followed by a self-retarded second-order reaction upon reaching the isothermal glass transition of the system.

A study of the curing process of compounds based on an epoxy oligomer ED-20 and metaphenylene diamine

The possibility of application of different mathematical models used to describe the dependence of viscosity and conversion on the curing time, as well as the rheokinetics of curing of an epoxyamine compound, is considered. It is shown that viscosity growth in the process of curing is determined by the degree of conversion and temperature.

Investigating the Tensile Behaviour of Blends of Polypropylene and a Statistical Copolymer of Propylene and Ethylene

Polypropylene-based materials are currently widely used in different sectors of industry. Polypropylene has high physicomechanical properties, good resistance to corrosive media, and a higher heat resistance than polyethylene – another popular large-tonnage polymer. A wide range of modifiers are used to control the processing and service properties of polypropylene [1]. These modifiers include substances of different nature, among which are other high-molecular-weight compounds [2, 3]. In this case we are speaking of polymer blends. Blends of polyolefins, including polypropylene, with other polymers have already been studied by a number of researchers. Slonimskii et al. [4] investigated the properties of polypropylene (PP) and polyethylene (PE), and also each of them with polyisobutylene (PIB). Composites consisting of crystalline and amorphous polymers (isotactic polypropylene–polyisobutylene, isotactic polypropylene–amorphous polypropylene, polyethylene–polyisobutylene), of crystalline polymers (polypropylene–polyethylene), and of amorphous polymers (atactic polypropylene–polyisobutylene) were investigated. On the basis of X-ray diffraction data and the nature of the thermomechanical curves, the authors came to the conclusion that the given blends, even a blend of atactic and isotactic polypropylene, are incompatible. The incompatibility of crystalline polypropylene and polyethylene is particularly marked. Mikhailov et al. [5], investigating the polypropylene–polyethylene system, came to a different conclusion. According to their data, a blend containing 75 wt% polyethylene and 25 wt% polypropylene is compatible. With a different ratio of components, incompatible composites are formed. Here, the strength of films of the polymer blend increases as the content of crystalline polymer in the blend increases. Such a picture is observed with increase in the content of isotactic polypropylene (PP) in a blend with amorphous polypropylene and in a blend with polyisobutylene (PIB), and also for a polyethylene–polyisobutylene blend. In a polypropylene–polyethylene blend, the presence of polypropylene leads to an increase in the strength of the polyethylene.

Effect of oxidation and modifiers on polypropylene crystallization

The effect of ester modifiers [di-n-alkyl esters derived from o-phthalic acid and C7-C9 alcohol fractions; poly(propylene glycol adipate) dibutyl ester] on the polypropylene oxidation and crystallization was studied. The modifiers influence the size of the crystallization nuclei and the polypropylene crystallization rate. Various models were used for mathematical description of the process, of which the Avrami model appeared to be the most adequate. The ester modifiers strongly influence the resistance of polypropylene to thermal oxidation: introduction of poly(propylene glycol adipate) dibutyl ester, thermodynamically incompatible with polypropylene, leads to a considerable increase in the induction period of oxidation.