Röntgen‐Weitwinkeluntersuchungen zur übermolekularen Struktur beim Cellulose‐I‐II‐Phasenübergang

Fink, Hans‐Peter; Fanter, Dale L.; Philipp, B.

doi:10.1002/actp.1985.010360101

Cited by 56 publications

(22 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The step width Δφ was 0.2 with a measurement time of 180 s/Δφ. The scattering curves were corrected for absorption, polarization, Compton scattering, and parasitic scattering [124,125]. From the corrected and normalized WAXS curves, the degree of crystallinity x c and the lattice disorder parameter k according to the Ruland-Vonk method, and the crystallite dimensions D (hkl) from the width of the reflections via the Scherrer equation were determined.…”

Section: Waxs and Birefringence Measurementsmentioning

confidence: 99%

Ionic Liquids for the Production of Man-Made Cellulosic Fibers: Opportunities and Challenges

Hummel

Michud

Tanttu

et al. 2015

Advances in Polymer Science

132

View full text Add to dashboard Cite

The constant worldwide increase in consumption of goods will also affect the textile market. The demand for cellulosic textile fibers is predicted to increase at such a rate that by 2030 there will be a considerable shortage, estimated at~15 million tons annually. Currently, man-made cellulosic fibers are produced commercially via the viscose and Lyocell™ processes. Ionic liquids (ILs) have been proposed as alternative solvents to circumvent certain problems associated with these existing processes. We first provide a comprehensive review of the progress in fiber spinning based on ILs over the last decade. A summary of the reports on the preparation of pure cellulosic and composite fibers is complemented by an overview of the rheological characteristics and thermal degradation of cellulose-IL solutions. In the second part, we present a non-imidazolium-based ionic liquid, 1,5-diazabicyclo[4.3.0]non-5-enium acetate, as an excellent solvent for cellulose fiber spinning. The use of moderate process temperatures in this process avoids the otherwise extensive cellulose degradation. The structural and morphological properties of the spun fibers are described, as determined by WAXS, birefringence, and SEM measurements. Mechanical properties are also reported. Further, the suitability of the spun fibers to produce yarns for various textile applications is discussed.

show abstract

Section: Waxs and Birefringence Measurementsmentioning

confidence: 99%

Ionic Liquids for the Production of Man-Made Cellulosic Fibers: Opportunities and Challenges

Hummel

Michud

Tanttu

et al. 2015

Advances in Polymer Science

132

View full text Add to dashboard Cite

show abstract

“…The degree of crystallinity is dependent on the origin of the cellulose as well as its subsequent processing (Fink and Walenta 1994;Liitiä et al 2003). In addition, different analytical techniques and methods often yield different degrees of crystallinity (Park et al 2010).…”

Section: The Structure Of a Cellulose Microfibrilmentioning

confidence: 99%

“…In addition, different analytical techniques and methods often yield different degrees of crystallinity (Park et al 2010). For example, according to X-ray diffraction (XRD), the crystallinity of cellulose in cotton linters is 56 to 63% (Fink and Walenta 1994), while according to nuclear magnetic resonance (NMR) spectroscopy, the crystallinity of cellulose in softwood is 49 to 54% (Andersson et al 2004). The crystallites within a single fiber are quite uniform in width as measured by wide-angle X-ray scattering (WAXS) technique (Hofmann et al 1989).…”

Section: The Structure Of a Cellulose Microfibrilmentioning

confidence: 99%

Proposed Nano-Scale Coalescence of Cellulose in Chemical Pulp Fibers During Technical Treatments

Pönni¹,

Vuorinen²

2012

BioResources

View full text Add to dashboard Cite

This review summarizes the proposed mechanisms for irreversible coalescence of cellulose microfibrils within fibers during various common industrial treatments for chemical pulp fibers as well as the methods to evaluate it. It is a phenomenon vital for cellulose accessibility but still under considerable debate. The proposed coalescence mechanisms include irreversible hydrogen bonding. Coalescence is induced by high temperature and by the absence of obstructing molecules, such as water, hemicelluloses, and lignin. The typical industrial processes, in the course of which nano-scale coalescence and possible aggregation of cellulose microfibrillar elements occurs, are drying and chemical pulping. Coalescence reduces cellulose accessibility and therefore, in several instances, the quality of cellulose as a raw material for novel products. The degree of coalescence also affects the processing and the quality of the products. For traditional paper-based products, the loss of strength properties is a major disadvantage. Some properties lost during coalescence can be restored to a certain extent by, e.g., beating. Several factors, such as charge, have an influence on the intensity of the coalescence. The evaluation of the phenomenon is commonly conducted by water retention value measurements. Other techniques, such as deuteration combined with FTIR spectroscopy, are being applied for better understanding of the changes in cellulose accessibility.

show abstract

“…Their physical properties, as well as their accessibility to chemical modification, swelling and adsorption phenomenon, are strongly influenced by their crystallinity. [12,[17][18][19][20] The structure of the cellulose microfibril surfaces and their interactions with other macromolecules is also dependent on the crystalline structure and on the packing of the cellulose sheets. [21] Since the studies of Meyer and co-workers [22][23][24] the crystalline structure and the packing of native cellulose chains has been the target of several investigations.…”

Section: Crystalline Structurementioning

confidence: 99%

Rodlike Cellulose Microcrystals: Structure, Properties, and Applications

Lima¹,

Borsali²

2004

Macromol. Rapid Commun.

794

343

View full text Add to dashboard Cite

Summary: In this article we present some interesting properties of rodlike cellulose microcrystals (so‐called “whiskers”). These microcrystals can be obtained from different cellulose sources such as wood, cotton, or animal origin. When submitted to acid hydrolysis, the cellulose fibers yield stable aqueous suspensions because of the presence of negative charges on the surface of the microcrystallites during the hydrolysis process. The obtained microcrystals are rod‐shaped particles, the dimensions of which depend on the cellulose origin. For instance, the cotton whiskers have typical dimensions varying from 100 to 300 nm in length, L, and 8 to 10 nm in diameter, d, while those of the tunicate whiskers range from 100 nm to few micrometers in length and 10 to 20 nm in diameter. At very low concentrations, these whiskers are randomly suspended in water and form an isotropic phase. When the concentration reaches a critical value, the whiskers spontaneously display ordered phases showing interesting liquid crystal properties (nematic and chiral nematic). The chiral nematic orders can be retained after evaporation of the solvent (generally water), leaving iridescent films. The reflected color can be controlled by changing either the ionic strength or by applying an electric field. These colloidal particles have been investigated using several techniques including small‐angle neutron scattering (SANS), small angle X‐ray scattering, rheology, and more recently dynamic and static light scattering techniques (DLS and SLS) to highlight their static and dynamic behavior. Because of their geometry, important axis ratio (L/d), and high crystallinity, these rods have been also extensively used to process nanocomposites based on polymer matrices, to reinforce their mechanical properties. All these properties are discussed in this contribution.Rodlike nanocrystals in aqueous suspension (left, Tunicate, 1 wt.‐%) and film (right), observed between cross‐polarizers.magnified imageRodlike nanocrystals in aqueous suspension (left, Tunicate, 1 wt.‐%) and film (right), observed between cross‐polarizers.

show abstract

Röntgen‐Weitwinkeluntersuchungen zur übermolekularen Struktur beim Cellulose‐I‐II‐Phasenübergang

Cited by 56 publications

References 24 publications

Ionic Liquids for the Production of Man-Made Cellulosic Fibers: Opportunities and Challenges

Ionic Liquids for the Production of Man-Made Cellulosic Fibers: Opportunities and Challenges

Proposed Nano-Scale Coalescence of Cellulose in Chemical Pulp Fibers During Technical Treatments

Rodlike Cellulose Microcrystals: Structure, Properties, and Applications

Contact Info

Product

Resources

About