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Study of wood surface pre-treatment by radio-frequency discharge plasma

Novák Igor, Sedliačik Ján, Krystofiak Tomasz, Lis Barbara, Popelka Anton, Kleinová Angela, Matyašovský Ján, Jurkovič Peter, Bekhta Pavlo

Drewno : prace naukowe, doniesienia, komunikaty

2019

vol. 62, nr 203

81--91

An investigation was made of wood of the species oak (Quercus petraea), beech (Fagus sylvatica L.), maple (Acer pseudoplatanus) and ash (Fraxinus excelsior) pre-treated using radio-frequency (RF) plasma in air at reduced pressure. Physical and chemical changes for all of the wood species were determined using measurements of water contact angles and FTIR-ATR spectroscopy. The results confirmed an increase in the wood’s hydrophilicity/polarity in all cases, caused by an increase in –OH group concentration due to irradiation by RF plasma. The content of oxygen-containing functional groups after treatment by RF plasma significantly increased, and the water contact angles were diminished. FTIR-ATR spectroscopy confirmed that RF plasma modification of the surfaces of all investigated wood samples led to certain changes, which were also dependent on the time of plasma exposure.

Influence of ECR-RF plasma modification on surface and thermal properties of polyester copolymer

El Fray M., Willert-Porada M.

Polish Journal of Chemical Technology

2015

Vol. 17, nr 4

115--119

In this paper we report a study on influence of radio-frequency (RF) plasma induced with electron cyclotron resonance (ECR) on multiblock copolymer containing butylene terephthalate hard segments (PBT) and butylene dilinoleate (BDLA) soft segments. The changes in thermal properties were studied by DSC. The changes in wettability of PBT-BDLA surfaces were studied by water contact angle (WCA). We found that ECR-RF plasma surface treatment for 60 s led to decrease of WCA, while prolonged exposure of plasma led to increase of WCA after N2 and N2O2 treatment up to 70°–80°. The O2 reduced the WCA to 50°–56°. IR measurements confirmed that the N2O2 plasma led to formation of polar groups. SEM investigations showed that plasma treatment led to minor surfaces changes. Collectively, plasma treatment, especially O2, induced surface hydrophilicity what could be beneficial for increased cell adhesion in future biomedical applications of these materials.

Surface modification of unsaturated polyester resins with perfluoropolyethers

Fabbri E., Fabbri P., Messori M., Pilati F., Tonelli C., Toselli M.

Polimery

2004

T. 49, nr 11-12

785-789

Fluorine-modified unsaturated polyester resins were prepared by using polycaprolactone/perfluoropolyether/polycaprolactone triblock copolymers having hydroxyl or methacrylate end-groups. Despite the immiscibility of the perfluoropolyether segment, all the modified resins were fully transparent after curing thanks to the compatibilization effect of the polycaprolactone segments. Contact angle measurements showed a very low water wettability for all investigated resin compositions. Also in the case of system with the lower bulk copolymer concentration (less than 0.3 phr) contact angle was higher than 94°. It has been demonstrated that the presence of methacrylate end-groups tends to hinder the surface segregation of the fluorinated additive.

Handlową nienasyconą żywicę poliestrową modyfikowano mieszając ją z różniącymi się składem trójblokowymi kopolimerami polikaprolakton/poli(perfluoroeter)/polikaprolakton [TXCL(y)] z końcowymi grupami hydroksylowymi lub metakrylanowymi [produkt reakcji TXCL(y)Acr z metakrylanem 2-izocyjanianu etylu]. Przebieg syntezy oraz otrzymane produkty scharakteryzowano metodami FT-IR (rys. 1) i 1H NMR (tabela 1, rys. 2). Pomimo znanego braku mieszalności segmentu poli(perfluoroeteru), wszystkie modyfikowane nim żywice były przezroczyste po utwardzeniu dzięki kompatybilizującemu wpływowi segmentów polikaprolaktonu. Modyfikowane produkty charakteryzowały się bardzo małą zwilżalnością wodą (znacznie większe wartości kąta zwilżania theta niż w przypadku żywic niemodyfikowanych). Wyniki badania kąta theta (rys. 3) wskazują też, że obecność końcowych grup metakrylanowych ogranicza powodującą hydrofobowość migrację segmentów fluorowych na powierzchnię.