The influence of extended mercerization on some properties of carboxymethyl cellulose (CMC)

Abstract

Carboxymethyl cellulose (CMC) is produced commercially in a two stage process consisting of a mercerization stage in which the pulp is treated with alkali in a water alcohol solution and a second etherification stage whereby monochloroacetic acid is added to the pulp slurry. In this study, the influence of the conditions of an extended mercerization stage was evaluated on the etherification stage concerning the degree of substitution (DS) and the filterability of the resulting CMC. The parameters studied were: (1) the ratio of cellulose I and cellulose II in the original pulp, (2) the concentration of alkali, (3) the temperature and (4) the retention time in the mercerization stage. The DS results indicate that the NaOH concentration in the mercerization stage is the most important among the parameters studied. When the NaOH concentration in the mercerization stage was high (27.5%), cellulose II showed a lower reactivity than cellulose I with respect to the DS obtained in the resulting CMC. The results from the filtration ability of CMC water solutions are interpreted that the amount of cellulose II in the original pulp and the temperature has a negative influence, while the NaOH concentration in the mercerization stage has a positive influence on the filtration ability. Retention time between 1 h-48 h in the mercerization stage had no effect on the DS or the filtration value. The filtration ability was assumed to be highly influenced by the presence of poorly reacted cellulose segments. The CMC samples with the lowest filtration ability at a given DS can be assumed to have the highest degree of unevenly substituted segments.

Carboxymethyl Cellulose Produced at Different Mercerization Conditions and Characterized by NIR FT Raman Spectroscopy in Combination with Multivariate Analytical Methods

“…As was reported earlier (Almlöf et al 2012), the fraction of cellulose II in the pulp, prior to CMC preparation, had no impact on the resulting DS value of the CMC when the NaOH concentration in the mercerization stage was 9%. In this case the DS was as low as 0.5, although the NaMCA charge was 2.04 mol NaMCA mol -1 AGU.…”

Study on Conditions for Carboxymethyl Cellulose Synthesis from Pineapple Leaf Waste and Evaluation of its Thickening Performance

“…Ethanol có vai trò làm trương các sợi cellulose [39,40], đồng thời để hòa tan và phân tán NaOH đồng đều tới các nhóm hydroxyl -OH trên mạch phân tử cellulose tạo thành cellulose kiềm hóa. Một lượng Na + và OHsẽ hòa tan và đi vào pha cồn ethanol, phần còn lại sẽ bị giữ lại trên bề mặt sợi cellulose và làm cho nồng độ NaOH cao hơn trong vùng bề mặt của cellulose, kết quả là làm trương và phá vỡ cấu trúc sợi cellulose, làm giảm số lượng liên kết hydro liên phân tử và làm tăng diện tích bề mặt phản ứng, từ đó thay đổi độ kết tinh và tính đa hình của cellulose [41]. Do đó, tỷ lệ thể tích ethanol so với khối lượng cellulose thường được nghiên cứu tối ưu cho phản ứng carboxymethyl hóa.…”