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RSC Sustainability
of those materials, reduced mass loss, and enhanced their thermal stability and ame retardancy. 42 Fig. 15 shows the XRD patterns of the calcium alginate bres, paper, and paper composites. The main peaks of an HBKP sample that appeared at approx. 14.8° (1 – 10), 16.3° (110), and 22.6° (200) in 2 q are typical of cellulose I. 43 The crystallinity of the HBKP sheet was 95.4%. Both the calcium alginate bre samples showed no signi cant crystal peak, indicating that calcium alginate bre is an amorphous material. 44 The crystallinities of the composite samples were 90.5%, 63.3%, 18.0%, 84.8%, 73.0%, and 62.2% for CA25, CA50, CA75, KA25, KA50, and KA75, respectively. When the composite was formulated with calcium alginate bres, the XRD pattern of the paper composite showed a decrease in crystallinity. This occurs because calcium alginate bre is an amorphous substance. This was attributed to the in uence of the nucleation process on the crystallinity of the composite polymers, as the amorphous calcium alginate bres disrupted the orderly arrangement of the polymer chains. 3.4.5 Chemical composition. Chemical composition anal- ysis was performed using XPS on calcium alginate bres a er heat treatment in a tube furnace at 200, 400, 600, and 800 °C. The results of the XPS full spectra are shown in Fig. 16a and b, with three corresponding peaks, C 1s (approximately 287 eV), O 1s (approximately. 534 eV), and Ca 2p (approximately 350 eV), along with their relative atomic composition ratios. The C 1s spectrum of CAF and KAF in Fig. 16c and d indicates four groups, including – C – O – C – (286.5 eV), 45 – C – O – (287.3 eV), 34,46 – C( ] O) – (288.5 eV), 45 and – COOH (290.5 eV), 34 respectively. These structures are derived from the macromolecular chains of cellulose and alginates. A er heat treatment at 200, 400, 600,
Fig. 15 XRD patterns of the calcium alginate fi bres, HBKP, and paper composites containing (a) commercial alginate fi bres (CA) and (b) kelp alginate fi bres (KA).
Fig. 16 XPS spectra of residual calcium alginate after thermal treatment at 200, 400, 600, and 800 °C in the wide scan of (a) the commercial alginate fi bre sample and (b) the kelp alginate fi bre sample, and high-resolution C 1s spectra of (c) commercial alginate fi bres and (d) kelp alginate fi bres.
608 | RSC Sustainability , 2025, 3 , 599 – 610
© 2025 The Author(s). Published by the Royal Society of Chemistry
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