the properties of polymer matrixes and fibrous fillers. Epoxy, phenolic and polyamide
matrixes are the most common. Epoxies have many varieties. Their operating
temperature is up to 473 K. Phenolic resins can be operated at temperatures up to
540 K. Polyamide resins are heat-resistant up to 650 K. While developing new PCM,
researches are conducted in two directions: the regulation of physico-mechanical and
other properties by selecting and modifying polymer matrixes and applying various
fillers with changing their geometric parameters or dressing their surfaces.
Thermosetting binders for PCM. The set of the properties of PCM depends on
the choice of the binder. So the advantage of epoxies are mechanical and dielectric
properties, low shrinkage during solidification, sufficient chemical resistance, but they
are characterized by insufficient heat resistance and high cost [2]. Polyester resins have
possibility of solidification at low temperatures and low cost as advantages, however,
they have low heat resistance and viability, and high flammability. Phenol-
formaldehyde resins (PFR) are widely used among polymer matrixes of structural
materials. They are characterized by high abrasion resistance, hardness, and the highest
heat resistance among well-known polymers. Due to these properties, as well as low
cost, phenol-formaldehyde resins are of industrial and commercial interest even more,
than 100 years after their invention.
However, the use of classical phenol-formaldehyde resins as an universal
thermosetting polymer matrix for PCM in many engineering areas is hampered by such
disadvantage as insufficiently high physico-mechanical indicators of phenol-
formaldehyde resins and, as a result, composite materials based on them. This is due
to both the high degree of cross-linking and the rigidity of the skeleton of aromatic
macromolecules of phenol-formaldehyde matrixes structure. Therefore, while creating
new PCM with improved physico-mechanical and tribological properties, various
modifications of thermosetting phenol-formaldehyde resins are carried out to eliminate
their main disadvantage - fragility. Phenol-formaldehyde matrixes are modified by the
low molecular weight compounds, and also by oligomers and polymers for improving
their strength properties. Thus, the researches for the modification of industrial phenol-
formaldehyde varnish LBS-1 (GOST 901-18) modified by polyamide
PA-6were
carried out. It was psrtly modified by oxymethylation of the amide group for increasing
its alcohol-solubility for further combination with an alcohol-soluble resin [3].
PCM based on the obtained polyamide-modified phenol-formaldehyde binder
with basalt discrete fiber filler with high strength and tribological characteristics were
obtained. The modification by organosilicon compound, phenyltriethoxylane water-
soluble phenol-formaldehyde resin with the low phenol content up to 1 mass.% is of
great interest
.
Binders based on it are environmentally friendly; there are no organic
solvents in their composition. The modification of phenol-formaldehyde resins by
epoxy oligomers is widely known. The properties of thermosetting matrixes which are
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