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Influence of the nanofiber dimensions on the properties of nanocellulose/poly(vinyl alcohol) aerogels 下载免费PDF全文
Silvana Mueller Janak Sapkota Apiradee Nicharat Tanja Zimmermann Philippe Tingaut Christoph Weder E. Johan Foster 《应用聚合物科学杂志》2015,132(13)
The investigation of aerogels made from cellulose nanofibers and poly(vinyl alcohol) (PVOH) as a polymeric binder is reported. Aerogels based on different nanocellulose types were studied to investigate the influence of the nanocellulose dimensions and their rigidity on the morphology and mechanical properties of the resulting aerogels. Thus, cellulose nanocrystals (CNCs) with low (10), medium (25), and high (80) aspect ratios, isolated from cotton, banana plants, and tunicates, respectively, microfibrillated cellulose (MFC) and microcrystalline cellulose (MCC) were dispersed in aqueous PVOH solutions and aerogels were prepared by freeze‐drying. In addition to the cellulose type, the PVOH‐ and the CNC‐concentration as well as the freeze‐drying conditions were varied, and the materials were optionally cross‐linked by an annealing step or the use of a chemical cross‐linker. The data reveal that at low PVOH content, rigid, high‐aspect ratio CNCs isolated from tunicates afford aerogels that show the least amount of shrinking upon freeze‐drying and display the best mechanical properties. However, with increasing concentration of PVOH or upon introduction of a chemical cross‐linker the differences between materials made from different nanocellulose types decrease. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41740. 相似文献
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The fabrication of nanocomposites of polyamide 12 (PA12) and cellulose nanocrystals (CNCs) isolated from cotton and tunicates is reported. Through a comparative study that involved solution‐cast (SC) and melt‐processed materials, it was shown that PA12/CNC nanocomposites can be prepared in a process that appears to be readily scalable to an industrial level. The results demonstrate that CNCs isolated from the biomass by phosphoric acid hydrolysis display both a sufficiently high thermal stability to permit melt processing with PA12, and a high compatibility with this polymer to allow the formation of nanocomposites in which the CNCs are well dispersed. Thus, PA12/CNC nanocomposites prepared by melt‐mixing the two components in a co‐rotating roller blade mixer and subsequent compression molding display mechanical properties that are comparable to those of SC reference materials. Young's modulus and maximum stress could be doubled in comparison to the neat PA12 by introduction of 10% (CNCs from tunicates) or 15% w/w (CNCs from cotton) CNCs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42752. 相似文献
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Honglawan A Beller DA Cavallaro M Kamien RD Stebe KJ Yang S 《Advanced materials (Deerfield Beach, Fla.)》2011,23(46):5519-5523
SU-8 pillar-assisted epitaxial assembly of toric focal conic domains (TFCDs) arrays of smectic-A liquid crystals is studied. The 3D nature of the pillar array is crucial to confine and direct the formation of TFCDs on the top of each pillar and between neighboring pillars, leading to highly ordered square and hexagonal array TFCDs. Excellent agreement between the experimentally obtained critical pillar diameter and elasticity calculation is found. 相似文献
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Ngoc X. B. Nguyen Apiradee Uthairatanakij Natta Laohakunjit Pongphen Jitareerat Kanokporn Boonsirichai Esther Shiau Ping Yap Ratchadaporn Kaprasob 《International Journal of Food Science & Technology》2022,57(6):3771-3782
Boiled peanuts are preferable as a ready-to-eat healthy snack; however, gamma irradiation as a postharvest treatment of raw peanuts may induce unfavourable food components. Hence, the phytochemical, antioxidant, and the texture of boiled ‘Tainan 9’ peanuts pretreated with gamma irradiation (0, 2.5, 5, and 10 kGy) and stored at 29 ± 2 °C for up to 180 days were investigated. Both gamma irradiation and storage time contributed to testa darkening in raw peanuts. In boiled irradiated products, irradiation doses and storage time affected the moisture content (MC), total proteins, total oil, total soluble sugars, and antioxidant capacity (P ≤ 0.05). Total phenolic and flavonoid contents showed an increase at days 90 and decreased at days 180 across all treatments. A positive correlation was observed among ferric reducing antioxidant power (FRAP), total phenolics, and total flavonoids. Gamma irradiation at 10 kGy led to increase of peroxide value (PV) (P ≤ 0.05), but malondialdehyde (MDA) content was unaffected. Textural properties of boiled irradiated peanuts were soft. As a result, gamma irradiation at 5 kGy is recommended for postharvest treatment of raw peanuts with subsequent storage up to 180 days to obtain the eating quality of boiled peanuts with good phytochemicals and antioxidant properties, which is a challenge for food industry. 相似文献
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Repeated phosphate removal from recirculating aquaculture system using cyanobacterium remediation and chitosan flocculation 下载免费PDF全文
Pranee Rojsitthisak Surachet Burut‐Archanai Apiradee Pothipongsa Sorawit Powtongsook 《Water and Environment Journal》2017,31(4):598-602
Unicellular cyanobacterium Synechocystis sp. was used for phosphate removal in a recirculating aquaculture system. The cell harvesting was performed using chitosan solution in this study. The parameters (i.e. cell density, pH of cell suspension and chitosan concentration) affecting the flocculation efficiency of chitosan were investigated. With the optimal condition, the repeated flocculation for phosphate removal in a photobioreactor was demonstrated. The results show that the flocculation efficiency of chitosan depends on cell density, pH of cell suspension and chitosan concentration. The optimal flocculation process could be accomplished by adjusting the pH to 7.2 before adding 20 mg/L chitosan followed by pH adjustment to 7.5. With single inoculation, the sequential process of phosphate removal using cyanobacterial uptake followed by cell flocculation using chitosan with the optimal condition in the photobioreactor was successfully achieved for 12 cycles with water from a recirculating fish tank. 相似文献
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Layer‐by‐layer modification of porous polybenzoxazine with silver nanoparticles for enhanced CO2 storage 下载免费PDF全文
Nicharat Manmuanpom Stephan Thierry Dubas Sujitra Wongkasemjit Thanyalak Chaisuwan 《应用聚合物科学杂志》2017,134(35)
Polybenzoxazine (PBZ) xerogels have been synthesized via quasi solventless method and coated with silver nanoparticles using the layer‐by‐layer (LbL) deposition method. After coating, the samples were carbonized at 800 °C to obtain high surface area porous carbon materials to be used for CO2 storage. Evidences of the successful LbL deposition of the coating was provided by ultraviolet–visible and attenuated total reflection–Fourier transform infrared spectroscopy and the silver nanoparticles top layer was confirmed by scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy. Results showed that the samples coated with silver nanoparticles displayed an increased CO2 capacity from 3.02 to 3.39 mmol g?1 when compared with the plain carbon PBZ. The LbL method for the modification of the pore surface in porous PBZ is simple and allows the facile tuning of the inner PBZ pore's surface chemistry with metallic nanoparticles that could be enhanced CO2 storage capacity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45097. 相似文献
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Temperature effect on microbial community of enhanced biological phosphorus removal system 总被引:28,自引:0,他引:28
Microbial population dynamics to gradual temperature change in an enhanced biological phosphorus removal system was kinetically investigated. As the temperature rose from 20.0 degrees C to 30.0 degrees C, and to 35.5 degrees C, the predominant microbial group changed from the phosphorus-accumulating organisms, PAOs (47-70% of total VSS) to the glycogen-accumulating organisms (64-75% of total VSS), and to the ordinary heterotrophs (90% of total VSS), respectively. Despite the species alteration, the phosphorus contents of the PAOs appeared to be steady within 0.182-0.308 mg/mg VSS(PAO) regardless of the temperature level. The initial specific phosphorus release rates, which are solely due to the PAOs activities, increased with the temperature from 37.5-55.9 to 51.8-61.3, 52.0-76.9, 147.2-210.3, and 374.2-756.3 mgP/gmVSS(PAO) h, at 20.0 degrees C, 25.0 degrees C, 30.0 degrees C, 32.5 degrees C, and 35.0 degrees C, respectively. On the other hand, mean initial specific phosphorus uptake rates of the biomass decreased as the temperature increased; however, the data implied that the rate of the PAOs was higher than the other two microbial groups. These results indicate that the PAOs are lower-range mesophiles or possibly psychrophiles. As the temperature rises, the portion of energy required for maintenance increases substantially which reduces the energy availability for cell reproduction; hence, the PAOs are washed out from the system. 相似文献