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Various composites were prepared by impregnation of cellulose fibre nonwovens (CFNs) with poly(vinyl alcohol) using two methods. The composites obtained contained up to 0.4 volume fraction of polymer, and the volume fraction of voids was not less than 0.3. Scanning electron microscope images show no great changes in CFN frame structure compared to untreated CFN. Air and water vapour permeability decreases with growth ofthe volume fraction of polymer as a result of filling ofthe voids and formation of closed voids. As determined by sorption characteristics, the composite and its base absorb water vapour differently from CFNs. Biodegradation of samples in soil was inspected. Test data show a faster degradation for samples with a small polymer amount, where less than 10% of initial weight is left after two weeks exposure in soil.

Some structural characteristics and properties of a diverse paper selection were studied with the aim to create biodegradable polymer composites for packaging materials. Paper in such composites would serve as a reinforcement and biodegradable polymer as a matrix. Tensile and tear properties of the tested papers depended not only on paper density (or void content) but also on some other paper structure features. As polymers for composite production are applied from solution, the impact of solvent on the mechanical properties of paper was investigated.On uuritud eri paberiliikide mõningaid struktuuri iseärasusi ja omadusi eesmärgiga moodustada biolagunevaid polümeerkomposiite pakkematerjalide tootmiseks. Sellistes komposiitides on biolagunev polümeer maatriksiks ja paber tugevdavaks komponendiks. Testitud paberite tõmbe-ja rebimisomadused ei sõltu ainult paberi tihedusest (või vabast mahust), vaid samuti mõnest teisest paberi struktuuri iseärasusest. Kuna kasutatava polümeeri tootmine toimub lahuses, on uuritud ka lahusti mõju paberi mehaanilistele omadustele.

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An experimental method (TWCS method) was applied to determine the flexural elastic modulus E and some other stress-deformation characteristics of a thin-walled circular cylindrical polymer shell at compression. A methodology of test sample preparation and fixation as well as means of the measurement of the load P and the respective displacement A were developed. Two modes of testing the equipment were used in which the sequences of measuring P ^> A and A^ P were implemented. Repeatability of measurements was evaluated. Optimal geometric parameters of test samples and the range of determinable values of modulus E were defined. A procedure of the calculation of the relationship between the tensile stress a and relative elastic tensile deformation e in the most defonned area of tlie sample was developed. Applicability of the TWCS method for multiple assessments of changes of deformational characteristics by using a single sample was proved. It was shown that creep, creep recovery, and stress relaxation tests can be performed by the TWCS method.