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Chemical treatment of recycled pulp fibers for property development: Part 2. Effects on old newspapers

100%

Sutcu A. , Sahin H. T. , Tutus A.

tom vol. 61, nr 201

177--192

The recycling of paper is an important issue and requires a systematic and investigative approach. However, it is necessary to scrutinize alternative methods on the strength of the development of recycled fibres to explore the impact of recycling on properties of recycled fibres. In this study, it was found that repeated treatments of recovered fibres with all three chemicals usually enhance their ability to re-swell and improve bonding potential in fibre networks. This is evidenced by higher water retention values (WRV) and improved strength properties. The highest WRV value of 2.65 g/g was observed with a 10.0% ethyl acetate treatment in the third recycling stage, which indicates approximately 660% higher WRV compared with control samples (0.34 g/g). Measurements also showed that the optical properties of lightness and the brightness properties of the sheets show variations. However, the highest brightness improvement of 3.8% was observed at 5.0% ethyl acetate treatment at the second recycling stage. This level of treatment has also given the highest lightness value of 73.97, which indicates only 0.54% improvement. The maximum tensile strength value of 23.89 N·m/g was observed at the third recycling stage with 10.0% formamide charge. However, this level of treatment also gave the highest burst at 1.50 kPa·m2/g and tear value of 2.88 N·m2/g, which indicates a 128.2% higher burst and 176.9% higher tear strengths, compared with control samples, respectively.

Research into the Process of Manufacturing Alginate - Chitosan Fibres

80%

Stęplewski W. , Wawro D. , Niekraszewicz A. , Ciechańska D.

tom Vol. 14, no. 4 (58)

25--31

The process of obtaining alginate-chitosan fibres intended for medical applications was the subject of our investigations. Two methods of forming two-component alginate-chitosan fibres of the core-skin type (calcium alginate and chitosan respectively) were developed. The first method of forming fibres (A), which consists in fibre spinning by feeding chitosan into a coagulation bath, allowed us to obtain alginate-chitosan fibres with a maximum chitosan content of about 3.1%. The second method (B) turned out to be more efficient. It consists in using chitosan in the finishing process, and enabled us to obtain alginate-chitosan fibres with a chitosan content of up to 9.2% wt. In order to further increase the chitosan content in the alginate-chitosan fibres manufactured by method B, polyvinylopyrrolidone (PVP), in amounts from 4% to 20% in relation to calcium alginate was introduced into the spinning solution. The two-component fibres manufactured with the use of PVP, and which included 11.6% wt of chitosan, were characterised by a tenacity of 22.2 cN/tex and an elongation at break of 19%. Additionally, the alginate-chitosan fibres of this type were characterised by very high water retention values (WRV) of up to 1300%, which makes these fibres suitable for use in sanitary and medical products.

Badano proces otrzymywania włókien alginianowo-chitozanowych, przeznaczonych do zastosowań medycznych. Opracowano dwie metody formowania dwuskładnikowych włókien alginianowo-chitozanowych typu rdzeń – alginian wapnia, otoczka – chitozan. Metoda (A) formowania, polegająca na wprowadzeniu chitozanu do kąpieli koagulacyjnej, umożliwiła otrzymanie włókien alginianowo-chitozanowych o maksymalnym udziale chitozanu ok. 3,1%. Bardziej efektywna okazała się metoda (B), polegająca na zastosowaniu chitozanu w obróbce wykończalniczej, która umożliwiła otrzymanie włókien alginianowo-chitozanowych, zawierających zawierających do 9,2% wag. chitozanu. W celu zwiększenia udziału chitozanu we włóknach alginianowo-chitozanowych formowanych metodą (B), do roztworu przędzalniczego wprowadzono poliwinylopirolidon (PVP) w ilości od 4 do 20% w stosunku do alginianu sodu. Włókna dwuskładnikowe wytworzone z udziałem PVP zawierające 11,6% wag. chitozanu charakteryzowały się wytrzymałością 22,2 cN/tex, wydłużeniem zrywającym 19% oraz bardzo wysokimi wartościami wskaźnika wtórnego pęcznienia do 1300%, co uzasadnia zastosowanie tych włókien do celów sanitarno-medycznych.