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Ramie provides the longest and strongest natural fiber in textile industry, but its traditional degumming process is costly and requires a large amount of alkali, which causes serious environmental concerns. In the current work, a steam explosion (STEX) treatment followed by sodium percarbonate (SP) soak degumming process was investigated. Microstructure, chemical composition and mechanical properties of the refined ramie fibers were comprehensively characterized. The residual gum content was below 5%, the fineness was higher than 1600 Nm (6.25 dtex), the breaking tenacity was 5.4 cN/dex, and the whiteness was above 50%. All of the properties met the requirements of Chinese national standard, and the breaking tenacity and whiteness were notably better than those of the fibers degummed traditionally. In addition, environmental impacts of the new degumming process were evaluated. Only 50% chemicals were needed for the new process, and chemical oxygen demand (COD) of the waste reduced to 35% of the traditional method. Therefore, the new method was more environment-friendly and economically feasible. It has great potential for industry applications. [ABSTRACT FROM AUTHOR]

• A method for splitting kenaf using microwave combined with lactic acid was proposed. • Fibers have excellent dispersion and suffer minor damage. • The extracted lignin is less damaged and keeps its structural integrity. • Potential for biomass clean production due to low chemicals and time consumption. According to diverse application purposes, different scales of lignocellulosic fibers were obtained from biomass through various preparation conditions. However, the pollution in the fiber separation process restricted the development of the related industry. This research proposed clean fiber separation technology of kenaf bast that combined microwave and lactic acid treatment. The traditional sulfate method was also carried out for comparison. The raw kenaf bast and produced fibers were characterized with wet chemistry analyses, SEM, FTIR, GPC and NMR. The results showed that compared with the traditional method (lignin removal rate 88.3 %, cellulose Mw = 607 kg/mol), the new method had higher lignin removal capacity (94.68 %) and less damage to cellulose (Mw = 1174 kg/mol). TG and NMR analysis showed that the separated crude lignin had a high pyrolysis temperature (350℃), minor structural changes and better uniformity, which was close to natural lignin. In addition, it was calculated that the processing time of the new method was reduced by 82.3 %, which reduced energy loss and waste liquid pollution. This study proved that microwave-assisted lactic acid treatment could separate kenaf fibers efficiently with less damage and pollution. [ABSTRACT FROM AUTHOR]

• Kapok fiber with thin cell wall and large lumen was used as supporting material for PCM. • The composite made by kapok and hollow PET fibers encapsulated PCM by vacuum impregnation. • This composite demonstrated obvious thermal regulating capacity in the cooling/hot environment. • The composite demonstrated robust leakage resistance to laundry, pressure and heat/cooling cycling. • This composite has great potential for dynamic heat insulation and thermal regulation. Kapok fiber, an agricultural product, is a typical cellulosic fiber with the features of thin cell wall and large lumen. Herein, a microtubule-based composite with high porosity of 98.03 % was prepared using kapok fibers and hollow PET. The kapok fiber-based composite successfully encapsulated a phase change material (PCM), that is a fatty acid ester of myristic acid and tetradecyl alcohol (MA-TD), in the microtubules by vacuum impregnation. The SEM showed that the PCM was encapsulated in the lumens of the fibers with a calculated percentage of 40.5 %. This condition provided the composite a basic thermal insulation from air pockets in the composite and a dynamic thermal insulation from the PCM. The kapok/PET/MA-TD could absorb 76.8 J/g latent heat in the comfort temperature range of 24 °C – 42.3 °C or release 77.4 J/g latent heat in the comfort temperature range of 29.7 °C – 10.5 °C. It withstood repeated laundry and exhibited robust leakage resistance to continuous heating/cooling under pressure. In addition, the composite was successfully used to dynamically regulate the temperature with obvious thermal regulating capacity in the simulated cooling/hot environments. Such material will be a robust candidate for dynamic heat regulating and thermal insulating applications. [ABSTRACT FROM AUTHOR]

• With the microwave-assisted ultrasonic treatment, the degumming process was more eco-friendly and efficient. • All properties were better than those of the fibers from traditionally degumming process. • The new method helped improve the technology for rapid and clean preparation of new biomass fibers. Apocynum venetum (AV) is a promising textile resource but lacks efficient degumming method. This study proposed a novel degumming process which coupled microwave pretreatment with ultrasonic degumming on AV bast. The traditional chemical degumming was also carried out for comparison. The raw AV bast and produced fibers were characterized with wet chemistry analyses, SEM, FTIR and GPC. Compared with traditionally degummed product, the AV fibers prepared by microwave-assisted ultrasonic degumming showed a better breaking tenacity (7.67 cN/dtex, comparing to 6.90 cN/dtex with the traditional method) and superior average length (32.5 mm, comparing to 23.0 mm). Moreover, compared with the traditional degumming method, the processing time of the new method was reduced to 31.2 %, and the chemical usage was reduced to 44.8 %. The new degumming method could efficiently produce higher quality AV fibers with less pollution. [ABSTRACT FROM AUTHOR]