Skoltech scientists conducted new studies of the mechanical properties of thermoplastic composites

Skoltech scientists conducted new studies of the mechanical properties of thermoplastic composites

Researchers from Skoltech have shown how fiberglass can be processed without significant deterioration of mechanical properties, and in some cases even with their improvement. New research could make building materials, car, airplane and marine parts, professional sports equipment and other products that end their lives in landfills greener, scientists say. The results of the study were published in the journal Composites Communications, the press service of Skoltech told Habra’s information service.

Fiberglass, carbon fiber, and other reinforced polymer composite materials are fiber-reinforced plastics of various types. For example, thermoset and thermoplastic composites are distinguished. These composites are produced at high temperature, but in the former, an irreversible chemical reaction occurs during solidification, and in the latter, a new shape can be given by repeated heating,

Scientists from Skoltech tested how repeated processing of a thermoplastic composite part affects its mechanical properties. For this, the researchers used fiberglass-reinforced polypropylene rods produced in another study. The rods were heated and pressed into flat slabs, then cut four times into strips, then heated and pressed into slabs again. The strength and elasticity of the products of each of the five “generations” were measured during mechanical tests.

Valentina Kravtsova

the first author of the study, a graduate of the master’s degree “Advanced production technologies” of “Skoltech”

“Not only that, the mechanical performance ultimately didn’t degrade as much as we expected; it turned out that sometimes recycling even made them better. The improvement of properties was noted in the first cycle of processing, when the shape of the product changed from a rod to a slab, and then the characteristics deteriorated slightly during further processing of slabs into slabs.”

Scientists explain the obtained research results by choosing the optimal processing technology. As the head of the study, Oleksandr Safonov, associate professor of the Skoltech Materials Technology Center, explained, it is important to preserve the length of the reinforcing fiber during processing. The researchers cut the slabs into strips parallel to the direction of the fibers and did not lose the length of the fiber due to this. However, if the plates are cut or crushed arbitrarily (as is usually the case), each cycle of processing will be associated with a noticeable decrease in the average fiber length and, as a result, a deterioration in mechanical characteristics.

As for the chemical composition of the material and its thermal properties, such as the melting point, they were also controlled at various stages of the experiment and processing will not affect these characteristics.

The results of the research give reason to expect that, in the presence of appropriate regulation, thermoset composites that are not easily disposed of can gradually be replaced by thermoplastic analogues. And these analogues will be able to get a second life without a noticeable loss of quality. However, the degree of influence of hot forming on the mechanical characteristics of processed products will depend on compliance with the technology and quality of the raw materials.

Kyrylo Minchenkov

co-author of a scientific article, graduate student of the “Mathematics and Mechanics” program of “Skoltech”

“Probably a relatively simple first step would be to apply hot forming directly in production to manufactured products with a marriage: from them you can immediately get parts of a different shape with the right characteristics. A similar stage in our experiment is the pressing of rods into slabs. The next step is to recycle goods that have reached the end of their useful life, instead of burying them in landfills, where thermosetting polymer composites now end up.”

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