Cellulose can be dissolved with another biopolymer in a protic ionic liquid and spun into a bicomponent hybrid cellulose fiber using the Ioncell
®
technology. Inside the hybrid fibers, the ...biopolymers are mixed at the nanoscale, and the second biopolymer provides the produced hybrid fiber new functional properties that can be fine-tuned by controlling its share in the fiber. In the present work, we present a fast and quantitative thermoanalytical method for the compositional analysis of man-made hybrid cellulose fibers by using thermogravimetric analysis (TGA) in combination with chemometrics. First, we incorporated 0–46 wt.% of lignin or chitosan in the hybrid fibers. Then, we analyzed their thermal decomposition behavior in a TGA device following a simple, one-hour thermal treatment protocol. With an analogy to spectroscopy, we show that the derivative thermogram can be used as a predictor in a multivariate regression model for determining the share of lignin or chitosan in the cellulose hybrid fibers. The method generated cross validation errors in the range 1.5–2.1 wt.% for lignin and chitosan. In addition, we discuss how the multivariate regression outperforms more common modeling methods such as those based on thermogram deconvolution or on linear superposition of reference thermograms. Moreover, we highlight the versatility of this thermoanalytical method—which could be applied to a wide range of composite materials, provided that their components can be thermally resolved—and illustrate it with an additional example on the measurement of polyester content in cellulose and polyester fiber blends. The method could predict the polyester content in the cellulose-polyester fiber blends with a cross validation error of 1.94 wt.% in the range of 0–100 wt.%. Finally, we give a list of recommendations on good experimental and modeling practices for the readers who want to extend the application of this thermoanalytical method to other composite materials.
A low carbon yield is a major limitation for the use of cellulose-based filaments as carbon fiber precursors. The present study aims to investigate the use of an abundant biopolymer chitosan as a ...natural charring agent particularly on enhancing the carbon yield of the cellulose-derived carbon fiber. The ionic liquid 1,5-diazabicyclo4.3.0non-5-enium acetate (DBNHOAc) was used for direct dissolution of cellulose and chitosan and to spin cellulose-chitosan composite fibers through a dry-jet wet spinning process (Ioncell). The homogenous distribution and tight packing of cellulose and chitosan revealed by X-ray scattering experiments enable a synergistic interaction between the two polymers during the pyrolysis reaction, resulting in a substantial increase of the carbon yield and preservation of mechanical properties of cellulose fiber compared to other cobiopolymers such as lignin and xylan.
The nanometric internal structure of polymeric fibres is fundamental for their mechanical properties. Two-dimensional small angle neutron scattering patterns were collected to obtain structural ...parameters of the elementary fibrils in regenerated cellulose fibres prepared by various fibre spinning technologies. Scattering features were fitted to model functions to derive parameters such as elementary fibril radius, long period of the repeating units of crystal and amorphous phase along the fibre axis, degree of orientation, and ellipticity. The correlation between structural parameters and the mechanical properties was studied for the fibres of different existing spinning processes and for the high-strength fibres. Former group showed high correlation with mechanical properties. The latter group showed generally lower correlation, but showed relatively high correlation with the long period. These structural parameters provide a basis for understanding the structure-property relationship of regenerated cellulose fibres as function of spinning types and conditions for further optimization.
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•Scattering length density of amorphous cellulose was modulated by solvation.•Four-point pattern were observed for Lyocell-based fibres.•Nanostructural parameters were evaluated from small angle neutron scattering.•Divergent nanostructures of regenerated cellulose fibres by spinning types.•Correlation between structural parameters and tensile properties were discussed.
Chitosan-cellulose composite fibers spun using a Lyocell technology are characterized by a homogeneous distribution and a close packing of the two biopolymers inside the fibrous matrix. Due to the ...intimate contact of cellulose and chitosan, synergistic effects can be observed during the pyrolysis of the composite fibers. In this study, the catalytic role of chitosan in altering the cellulose pyrolysis pathway in the composite fibers at moderate treatment temperatures up to 900 °C is confirmed. Analyses of the evolved gases during pyrolysis revealed that chitosan promoted cellulose dehydration and substantially decreased the formation of levoglucosan, explaining the higher char yield. The enhanced dehydration reaction is associated with the formation of intermolecular crosslinks due to the incorporation of nitrogen from chitosan in the resulting carbon structures. Nitrogen could also contribute to the in-plane disorder in the aromatic clusters when the pyrolysis is carried out at 500–700 °C, although the in-plane disorder is less noticeable from 700 to 900 °C. Nevertheless, the size of the aromatic cluster continues to grow when the composite fibers are pyrolyzed in a temperature range of 500–900 °C.
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Previous studies indicated that using CO2 as a reaction agent in the pyrolysis of biomass led to an enhanced generation of syngas via direct reaction between volatile organic carbons (VOCs) evolved ...from the thermal degradation of biomass and CO2. In addition, the physico-chemical properties of biochar in CO2 were modified. In this current study, biochars generated from red pepper stalks in N2 and CO2 (RPS-N and RPS-C, respectively) were tested for their effects on the immobilization of Pb, Cd, Zn, and As in contaminated soils. Soils were incubated for one month with 2.5% of RPS, and two biochars (i.e., RPS-N and RPS-C) at 25°C. After the incubation period soils were analyzed to determine the amendment effects on the behavior of metal(loid)s. The potential availability and mobility kinetics of metal(loid)s were assessed by single extraction of ammonium acetate and consecutive extraction of calcium chloride, respectively. Sequential extraction was used to further examine potential changes in geochemical fractions of metal(loid)s. The increased soil pH induced by application of the biochars reduced the potentially available Pb, Cd, and Zn, while RPS-C significantly reduced Pb due to the high surface area and aromaticity of RPS-C. However, RPS-C mobilized potentially available As compared to RPS-N due to the increased soil pH. Biochars reduced the mobility kinetics of Pb, Cd, and Zn, and RPS-N effectuated the greatest reduction of As mobility. The RPS-C increased the Fe and Mn oxides, hydroxide, and organically bound Pb, while both biochars and RPS-N increased residual Cd and Zn, and organically bound As, respectively. When considering the two biochars, RPS-C was highly effective for immobilization of Pb in soils, but it had no effect on Cd and Zn and a negative effect on As. In addition, RPS-C significantly increased the total exchangeable cations in soils.
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•Biochars markedly reduced Cd, Pb and Zn mobility in soils.•Biochar pyrolyzed in CO2 most effectively immobilized Pb.•Biochar pyrolyzed in CO2 increases As mobility more.•More siloxane groups present in biochar pyrolysed in CO2.
Penelitian ini mengkaji mengenai Implementasi Permainan Tradisional dalam Mengembangkan Nilai-nilai Agama dan Moral Anak Usia Dini di kabupaten Deli Serdang. Penelitian kualitatif dengan model ...humanistik dan teknik observasi, wawancara dan dokumentasi serta dilengkapi dengan analisa data dan keabsahan data. Maka, hasil penelitian menunjukkan bahwa penerapan permainan tradisional congklak, bekelan, engklek, lompat tali dan engklek dimulai dengan perancangan program pembelajaran hingga pada pelaksanan dan evaluasi. Ditemukan perkembangan nilai-nilai agama dan moral anak usia dini yang signifikan pada TKIT harvysah rata-rata 77,8. Sedangkan pada TKIT Umi Erni rata-rata 79,73 artinya berkembang sesuai harapan. adapun faktor pendukung dan penghambatnya yaitu guru, anak, media pembelajaran, sarana prasarana serta lingkungan dan budaya. Penelitian ini diharapkan berkontribusi bagi kegiatan bermain sambil belajar melalui pelestarian permainan tradisional bagi lembaga pendidikan dan khususnya anak usia dini.
Penelitian yang dilakukan ini merupakan tentang metode dan Proses pembelajaran anak usia dini ditekankan pada proses belajar melalui bermain. Hal ini dilakukan untuk melatih keterampilan dasar. ...Melalui kegiatan bermain, anak dapat melibatkan diri dan bereksplorasi untuk memperkuat hal-hal yang dimiliki dan menemukan pengetahuan baru. Proses pembelajaran yang dilaksanakan bertujuan untuk mengoptimalkan aspek pengembangan anak. Proses belajar dengan strategi bermain dilaksanakan sesuai dengan tujuan yang telah ditentukan. Model belajar melalui bermain yang dipakai adalah bermain terbimbing dan diarahkan karena cenderung memakai media pembelajaran. Proses belajar yang dilaksanakan cenderung klasikal dengan materi dan metode yang sama secara serentak dan diterapkan bagi semua anak. Proses pembelajaran yang dilaksanakan dibuat variatif sesuai keunikan setiap anak sehingga dalam proses belajar dapat dikondisikan untuk memilih sudut permainan sesuai minat dan pilihannya.
Pembelajaran anak usia dini dilembaga pendidikan anak usia dini, musik merupakan bagian dari kegiatan pembelajaran sehari-hari. Aspek perkembangan seni dan musik anak usia dini harus dikembangkan ...dejak usia dini. Pembelajaran seni suara dan musik pada anak usia dini tidaklah rumit guru hanya perlu menyediakan strategi yang benar dalam pembelajarannya. Penelitian yang digunakan oleh penulis ialah media dan wawancara, dalam pelaksanaanya menggunakan penelitian secara langsung dan tidak langsung. Penulis tertarik untuk mengangkat judul ini karena penulis ingin mengetahui bagaimana cara guru dalam mengembangkan aspek perkembangan seni suara dan musik pada anak usia dini. Terdapat lokasi penelitian pada penelitian kali ini yaitu di TK Nurul Azmi.
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