木质素与半纤维素对稻草秸秆酶解的影响

分别采用稀酸和酸碱顺序两种方法处理稻草秸秆,20 FPU/g(底物干重)的纤维素酶、底物质量浓度为80 g/L,45℃酶解72 h。结果表明,木质素与半纤维素对纤维素转化为葡萄糖都有较大影响,稀酸处理的秸秆酶解纤维素转化率(43.4%,葡萄糖质量浓度24.1 g/L)是未处理秸秆(16.8%,葡萄糖质量浓度6.2 g/L)的2.6倍,而酸碱顺序处理的秸秆(60.6%,葡萄糖质量浓度47.7 g/L)则是未处理秸秆的3.6倍。采用上述两种方法处理秸秆后,秸秆木质素和半纤维素被移去,秸秆结构发生改变,从而秸秆纤维更易受纤维素酶的攻击,并且秸秆木质素和半纤维素质量分数越低,纤维素的酶解得率就越高。     

碱煮法提取稻秸秆纤维的工艺及性能探讨

通过L16(45)正交试验方法研究碱煮法提取稻秸秆纤维的工艺参数优化方案,确定烧碱浓度、碱液温度、反应时间、搅拌速度和固液比等因素与提取的稻秸秆纤维组成及性能的关系。结果表明:最佳的工艺组合是碱液温度90℃、反应时间120min、搅拌速度720r/min、固液比1g∶30ml、秸秆/氢氧化钠(质量比)1∶0.6;稻秸秆纤维的最佳性能是平均长度10.3mm,宽度19.3μm,成纤率25.88%,未离散率0.5%,纤维中纤维素成分质量分数为74.85%,灰分质量分数为2.21%。对最佳工艺参数下制备的稻秸秆纤维进行了微观结构和红外分析,为后期研究新型稻秸秆纤维复合材料提供参考依据。     

Physicochemical and Thermal Properties of Ceiba pentandra Bark Fiber

Owing to their low weight-to-high strength ratio and recyclable features, the natural fibers are the most potential choice in place of synthetic fibers and been used as reinforcement materials in polymer matrix composites. Characterization of Ceiba pentandra bark fibers (CPFs) such chemical analysis, Fourier Transform-Infrared Analysis (FTIR), X-ray diffraction, thermogravimetric analysis, and Differential thermogravimetric analysis (DTG) analysis has analyzed. CPFs contain 60.9% (w/w) of cellulose, 17.5% (w/w) of hemicellulose, and 23.5% (w/w) of lignin. Besides, its density and crystallinity index are 682 kg m^?3 and 57.94%, respectively. TG and DTG analysis discovered that CPFs are thermally stable up to 342.1°C. Further, all the resources of CPFs ensured that it can be an excellent alternative for synthetic fibers in polymer matrix composites.     

Influence of Surgarcane Bagasse Fibers with Modified Surface on Polypropylene Composites

Sugarcane bagasse fibers were pre-treated with sulfuric acid solution to improve the mechanical properties of polypropylene (PP) composites for automotive parts. It was used maleic anhydride grafted polypropylene (PP-g-MA) as coupling agent. Fibers were characterized by the techniques of scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. The chemical composition of fibers was also evaluated. PP was mixed to fibers, in proportions of 5 to 10% (wt/wt) using a thermokinetic mixer model MH-50H. Furthermore tensile specimens were prepared for evaluation of mechanical properties by tensile test. Pre-treatment fibers permitted the removal of other components from sugarcane bagasse. The chemical treatment reduced some of the fibers amorphous components, causing changes in their surface.

The addition of pre-treated and compatibilizedfibers to PP matrix caused an increase in the elastic modulus in tensile. It was possible to obtain a more rigid and less deformable material with up to 10% fiber content. However, the use of the coupling agent showed results superior to other composites.     

Microscale analysis of in vitro anaerobic degradation of lignocellulosic wastes by rumen microorganisms

Anaerobic degradation of lignin in waste straw by ruminal microbes was directly observed using atomic force microscope (AFM). A series of high-resolution AFM images of the straw surface in the biodegradation show that the wax flakelets and lignin granules covering the straw surface were removed by the rumen microorganisms. Such degradation resulted in an exposure of cellulose fibers located inside the straw. The appearance of holes and microfibers in fermentation reveals that tunneling might be one of the ways for rumen microorganisms to attack the straw. Increases in the atomic ratio of oxygen to carbon (O/C) and the ratio C2/C3 in C1s spectra of X-ray photoelectron spectroscopy confirm that more cellulose was exposed on the surface after the anaerobic fermentation of straw. Gas chromatography/mass spectrometry analytical results demonstrate the decomposition of lignin by rumen microorganisms. Fourier transform infrared spectroscopy spectra and the measurement of degradation efficiency of the main straw components further verify these microscaled observations.     

Cello-oligosaccharides production from multi-stage enzymatic hydrolysis by lignocellulosic biomass and evaluation of prebiotic potential

Cello-oligosaccharides (COS) are very recent promising water-soluble dietary fibers, which favors several application in food, chemical and pharmaceutical industries. A three-stage enzymatic hydrolysis of cellulose extracted from agroindustrial wastes (sugarcane straw and coffee husk) with the 1,4-β-endoglucanase cellulase of glycoside hydrolase family (GH12) was developed with a processing time of 48 h. Finds evidenced that removal of products (glucose and cello-oligosaccharides) at each stage provided an increase in cello-oligosaccharides enzymatic hydrolysis in yield of approximately 65%. COS promoted growth of Lactobacillus acidophilus and Lactobacillus brevis after 24 h of fermentation, although they have presented low efficiency with Bifidobacterium sp. This multi-stage enzymatic hydrolysis has potential as a successful strategy to reduction enzyme requirements for COS production with prebiotic properties.Industrial relevanceThis work proposes an innovative technology of multi-stage enzymatic hydrolysis using the enzyme adsorbed on the cellulose surface obtained from renewable sources (sugarcane straw and coffee husk). This strategy is potential to increase the COS yield production and possibly make its cost-viable. The study is also relevant due to accessing the growth promotion of a representative selection of probiotic Lactobacillus and Bifidobacterium strains in order to evidence their prebiotic potential to be used as a possible functional ingredient for the pharmaceutical and food industries.     

Characterization of New Natural Cellulosic Fiber from the Bark of Dichrostachys Cinerea

The increasing environmental awareness has directed attention of the researchers towards the field of natural fiber composites. The aim of this investigation is to understand the physico-chemical properties of fibers extracted from the bark of the Dichrostachys Cinerea (DC) plant. Dichrostachys Cinerea fibers (DCFs) has cellulose (72.4 wt. %), hemicellulose (13.08 wt. %), lignin (16.89 wt. %), density (1240 kg/m³), crystallinity index (57.82%), and tensile strength (873 ± 14 MPa). Besides the cellulose degradation of DCFs at 359.3° vide by the thermo-gravimetric analysis and chemical groups are identified by Fourier transform analysis. Eventually the characterization results of DCFs strongly show the possibility of reinforcement in polymer matrices.     

富含纤维素类植物的纤维提取

农产品主要残余物的稻草、麦秸、甘蔗渣、玉米杆等都富含纤维状物质和纤维素。选用稻草、甘蔗皮为原料,采用碱煮及漂白工艺对原料进行相应处理,产物中获得了一定的纤维型材,通过调整和控制工艺参数,可提高产物中纤维型材的获取比例,产物中非纤维状物质主要为纤维素。     

Thespesia populnea Reinforced Cashew Nut Husk Tannin-Based Polyurethane Composites

Polyurethane composites were prepared by reinforcing raw and silane treated Thespesia populnea fibers in random orientations at different fiber length and loadings with polyurethane. The matrix phase is bio- polyurethane (PU1 and PU2), prepared from tannin extracted from Cashewnut husk with Hexamethylene diisocyanate in the absence and presence of extender. Surface modification was carried out with vinyltriethyl silane as coupling agent. Tensile, compression and moisture absorption properties of the composites were evaluated and fiber properties analysed. Results showed that composites had better mechanical properties compared to the non reinforced matrix. Composites from PU1 had better mechanical properties compared to that of PU2. Tensile and compression strength decreased with increase in fiber content in the matrix. PU1 based composites had less moisture absorption than PU2 based composites and the amount of absorption increased with increase in fiber length. The paper suggests that Thespesia populnea fibers have immense scope as reinforcement in the composite industry.     

碱处理对旧报纸纤维/聚乳酸复合材料力学性能的影响

利用注射成形工艺制备了旧报纸纤维(NRF)/聚乳酸(PLA)复合材料,探讨了碱处理对NRF/PLA复合材料力学性能的影响。结果表明,碱处理可使旧报纸纤维中部分半纤维素和果胶等物质溶出,纤维表面极性降低,旧报纸纤维与聚乳酸相容性得到改善;碱处理后的旧报纸纤维纤维素结晶度增大,纤维表面孔径增大,比表面积增加,纤维表面油墨被去除,旧报纸纤维与聚乳酸界面结合性能得到改善,NRF/PLA复合材料力学性能提高。