Ключевые слова: смеси полимеров, специфическое волокнообразование, фильтрующие материалы, компатибилизатор, ультратонкие волокна.
Tsebrenko I.A. Developing of the production technology of thinfibrous filter materials from polymer mixtures with the specific interactions of components – Manuscript. Candidate degree thesis by speciality 05.17.15 – Technology of chemical fibers. – Kyiv State University of Technologies and Designe, Kyiv, 2000.
The thesis is devoted to developing of the production technology of new filter materials with purifying degree 0,45 and 0,3m on the basis of ultrathin polypropylene fibers. The goal of this work has been achieved by using of the ternary polymer mixtures. Processing of polymer mixture melts opens a new way to obtaining of ultrathin synthetic fibers, or microfibers. When mixture of immiscible polymers flow through a die, the dispesed phase polymer (fibre-forming) forms within another (matrix) polymer a great number of microfibers oriented in the flow direction. This phenomenon has been called the specific fiber-formation. Thanks to transient layer forming at the components interphase during the flow, ultrathin fibers have unique structure of the surface: each fiber is covered by a multitude of superthin fibrils that are the branches of the main fiber. From the investigation carried out previously it is known that the specific fiber-formation phenomenon is established to the highest extent at content of fiber-forming polymer in mixture (20-30) wt%. At the disperse phase polymer content (40-60) wt% the phase inversion occurs: the disperse phase and dispersion medium exchange their roles. At phase inversion both phases are continuous and the specific fiber-formation was not observed.
In this dissertation work at the first time it has been shown that introduction in binary polymer mixture of the third component of polymer or nonpolymer nature (so named interfacial tension modifiers or compatibilizators) allows to realise the specific fiber-formation phenomenon at ratios of fiber-forming and matrix components 40/60; 50/50; 60/40 corresponding to the region of phase inversion. Objects of the investigation were polypropylene-co-polyamide (PP/CPA) mixture with component ratios 20/80; 30/70; 40/60; 50/50; 60/40 wt%. As additives it was recomended: ethylene and vinylacetate copolymer (EVAC), polyoxymethylene (POM), sodium oleate. The structureformation processes, phase transitions, micro- and macrorheological properties of binary and ternary mixture melts have been investigated. Using the enumerated additives has allowed to realise the PP fiber-formation in CPA matrix at PP/CPA ratios 40/60; 50/50; 60/40 corresponding to the region of fhase inversion. Forming PP microfibers in CPA mass is explained by improving of miscibility between CPA and additive molecules at the interphase. The types of the pointed interactions has been found by the infrared spetroscopy method. They are: dipole-dipole and ion-dipole bonds.
It has been shown that the enumerated additives play role of compatibilization improving miscibility of polymers of the binary mixtures, increasing the kinetic stability of mixtures and degree of dispertion in the co-polyamide matrix at the expense of specific interactions.
The peculiarities of rheological properties of polymer mixture melts with the specific interactions between components at the interphase have been found. They are: increasing of the viscosity from the additional structuration of melt by intermolecular bonds; increasing of the elasticity of ternary mixture melts as compared to elasticity of binary mixture melts. The latter is explained by forcefully streching of the disperse phase polymer and realisation of the specific fiber-formation phenomenon. The capability of the ternary polymer melts to longitudinal deformation (spinnability) sharply increases. It has been shown that there is a temperature superposition for dependence viscosity versus shear rate in reduced coordinates of Vinogradov-Malkin.
At the first time the extremely high stability of CEVA microfibers to fracture on droplets in accordance with Tomotika's mechanism has been found. This is explained by stabilization action of the anomaly high elastic deformations accumulated during flowing of the mixture melt.
It has been shown that PP dispersed state (as microfibers) in the ternary mixtures causes sharp lowering of this heat values at phase transition and also appearance of additional low temperature peaks on crystallisation thermograms.
It has been determined that the fiber-forming properties of polymer mixture melts can be regulated by changing of the chamical nature of the mixture components, structure-formation processes and by introducing of various additives of polymer and nonpolymer nature into binary mixture. The mechanism of additives action is connected with changing of microrheological processes during mixture melt flowing under the influence of the specific interactions between polymer macromolecules and additives at the interphase. The complex thread consisting of hundreds thousads of PP microfibers has been produced at forming composite monothread (of the polymer mixture) through the die with single hole. There are the following distinctiv properties of the complex threads consisting of microfibers: high strength and initial modulus, high elasticity, exclusitive softness pleasant feel, coupling, capasiousness, and woollikeness without special textural procedures, high sorption of moisture, dyes and other substances.
The results of this dissertation work give the possibility to develop the technology of production of new filter materials with purifying degree 0,45 and 0,3μm on basis of ultrathin polypropylene fibers. The experimental lot of filters developed was produced. Filters have been enculcated on the enterprises of medical, biological and food industry. The self reinforced composite threads with high physical-mechanical properties have been obtained by processing of PP/EVAC mixture melts.
Key words: polymer mixtures, specific fiber-formation, filter materials, compatibilizator, ultrathin fibers.