The Relationship between Crystal Structure and Mechanical Performance for Fabrication of Regenerated Cellulose Film through Coagulation Conditions

Cellulose films regenerated from aqueous alkali–urea solution possess different properties depending on coagulation conditions. However, the correlation between coagulant species and properties of regenerated cellulose (RC) films has not been clarified yet. In this study, RC films were prepared from cellulose nanofiber (CNF) and microcrystalline cellulose (MCC) under several coagulation conditions. Cellulose dissolved in aqueous LiOH–urea solution was regenerated using various solvents at ambient temperature to investigate the effects of their dielectric constant on the properties of RC film. The crystal structure, mechanical properties, and surface morphology of prepared RC films were analyzed using X-ray diffraction (XRD), tensile tester, and atomic probe microscopy (AFM), respectively. It is revealed that the preferential orientation of (110) and (020) crystal planes, which are formed by inter- and intramolecular hydrogen bonding in cellulose crystal regions, changed depending on coagulant species. Furthermore, we found out that tensile strength, elongation at break, and crystal structure properties of RC films strongly correlate to the dielectric constant of solvents used for the coagulation process. This work, therefore, would be able to provide an indicator to control the mechanical performance of RC film depending on its application and to develop detailed researches on controlling the crystal structure of cellulose.

Cellulose Film with Air Barrier and Moisture-Conducting Character Fabricated by a Green Process

The use of nature polymer to prepare degradable films is a sustainable production concept that can improve resource utilization and reduce the environmental pollution caused by traditional packaging waste or another field. Here, a regenerated cellulose film was prepared through the N-methylmorpholine-N-oxide (NMMO) cellulose system. The most critical peculiarity is that films with air barrier and moisture conduction character, because the surface of film is dense and does not allow small molecules like oxygen to pass through, but water molecules can move freely in the film by means of hydrogen bonds. This shows that the cellulose film has in textiles, food preservation, medicine and other fields. Significantly, the film has good tensile strength (maximum strength reaches 149.5 MPa) and light transmittance (more than 80% at 600 nm). Moreover, the effect of coagulation bath concentration, temperature and the content of glycerin on film strength was discussed.

The Control of Crystal Structure and Mechanical Property in Regenerated Cellulose Film by Coagulation Conditions

Cellulose films regenerated from aqueous alkali-urea solution possess different properties depending on coagulation conditions. However, the correlation between coagulant species and properties of regenerated cellulose (RC) films has not been clarified yet. In this study, RC films were prepared from cellulose nanofiber (CNF) and microcrystalline cellulose (MCC) under several coagulation conditions. Cellulose dissolved in aqueous LiOH/urea solution was regenerated using various solvents at ambient temperature to investigate the effects of their polarity on the properties of RC film. The crystal structure, mechanical properties, and surface morphology of prepared RC films were analyzed using X-ray diffraction (XRD), tensile tester, and atomic probe microscopy (AFM), respectively. It is revealed that the preferential orientation of (110) and (020) crystal planes, which are formed by intra- and inter-hydrogen bonding in cellulose crystal regions, changed depending on coagulant species. Furthermore, we found out that tensile strength, elongation at break, and crystal structure properties of RC film strongly correlate to the dielectric constant of solvents used for coagulation process. This work, therefore, would be able to provide an indicator to control the properties of RC film depending on its application and to develop the detailed research on controlling the crystal structure of cellulose.

Cellulose-Based Flexible Organic Light-Emitting Diodes with Enhanced Stability and External Quantum Efficiency

A cellulose-based flexible organic light-emitting diode (OLED) with enhanced stability and light extraction efficiency was prepared by using a PEDOT:PSS PH1000 transparent conductive electrode coated on regenerated cellulose film (RCF)....

Flexible and conductive cellulose substrate by layered growth of silver nanowires and indium-doped tin oxide

Regenerated cellulose film (RCF) has potential as a conductive substrate due to features such as its degradability, transparency, and flexibility. Indium doped tin oxide (ITO) is a conventional conductive material, but its rigidity restricts the formation of flexible conductive film. In this study, silver nanowires (AgNWs) were introduced between the RCF and the ITO conductive framework. Additionally, the fabrication of flexible, conductive, and transparent RCF was conducted. The AgNWs-ITO based RCF demonstrated high conductivity (170 Ω per sq) and transparency (78%) by the addition of 50 μL of AgNWs. After bending the sample 50 times with a 5 mm curve radius, the as-prepared conductive RCF presented an electric resistance improvement of 19%, with a 485% increase for the control ITO-based RCF. This is a result of the AgNWs framework, which can lessen the destruction of the bending treatment on the conductive layer and can also desirably connect the ITO conductive sections. The novel approach can expedite the versatile applications of flexibly conductive RCF on printable, portable, and wearable electronic devices.

Optical cellulose fiber made from regenerated cellulose and cellulose acetate for water sensor applications

In this study an optical cellulose fiber for water sensoring was prepared by using a sequential preparation strategy. The core of the fiber was prepared from dissolved cellulose, in [EMIM]OAc, which was dry–wet spun into water. The cladding layer on the cellulose core was produced by coating a layer of cellulose acetate, dissolved in acetone, using a filament coater. The chemical and optical properties of both regenerated cellulose and cellulose acetate were studied from cast films using ultraviolet–visible and Fourier-transform infrared spectroscopy measurements. Regenerated cellulose film was observed to absorb UV light, passing the visible light wavelengths. Cellulose acetate film was observed to pass the whole light wavelength range. The mechanical strength and topography of the prepared optical cellulose fiber were investigated through tensile testing and SEM imaging. The mechanical performance of the fiber was similar to previously reported values in the literature (tensile strength of 120 MPa). The prepared optical fiber guided light in the range of 500–1400 nm. The attenuation constant of the cellulose fiber was observed to be 6.3 dB/cm at 1300 nm. The use of prepared optical cellulose fiber in a water sensor application was demonstrated. When the fiber was placed in water, a clear attenuation in the light intensity was observed. The studied optical fiber could be used in sensor applications, in which easy modifiability and high thermal resistance are beneficial characteristics. Graphic abstract Coaxial cellulose acetate-regenerated cellulose fiber for transporting light in sensor optical fiber sensor applications.