Fractal structure and hydration-driven shape memory of duck down in the dry–wet state

2021 ◽  
pp. 004051752110600
Author(s):  
Wei-dong Yu ◽  
Zhaoqun Du ◽  
Hongling Liu ◽  
Weidong Yu
Keyword(s):  
Shape Memory ◽  
Fractal Structure ◽  
Fiber Diameter ◽  
Synthetic Polymers ◽  
Natural State ◽  
Filling Material ◽  
Bifurcation Structure ◽  
Heat Setting ◽  
Memory Mechanism ◽  
Self Similar

Duck down, as a natural keratin material, has been widely used as a filling material. The multilevel bifurcation structure of down has been observed and characterized through scanning electron microscopy. The structure is a complex fractal structure composed of four-level self-similar structures including five units, that is, the calamus, main barb, barb, barbule, and node or prong. The differential friction effect of the dynamic friction coefficients of the barb was reduced from 0.4 (dry state) to 0.23 (wet state), namely a decrease of 42.5%. The friction locking effect decreases due to the swelling of the fiber diameter. The down is zero gravity in water, and under the action of vibration and internal stress, down that has been subjected to friction or heat setting treatment can quickly return to its original shape in water. This shape memory mechanism was further confirmed, in which down after heat setting can restore its shape to the natural state by shaking it quickly and vigorously. This research provides inspiration to investigate more complicated functions of natural materials and encourages the creation of very intelligent synthetic polymers.

scholarly journals Turbulence and magnetic fields in molecular clouds

1991 ◽  
Vol 147 ◽  
pp. 83-92
Author(s):  
R. N. Henriksen
Keyword(s):  
Magnetic Fields ◽  
Wavelet Analysis ◽  
Molecular Clouds ◽  
Fractal Structure ◽  
Compressible Turbulence ◽  
Dynamo Theory ◽  
First Results ◽  
Self Similar

in this paper I first review some of the simple structural concepts associated with compressible turbulence. In particular the hierarchical or self-similar fractal structure to be expected is formulated in a manner readily compared to the observations, and to previous work. In the next section I present the first results of a wavelet analysis on molecular clouds, which seem to comfirm the hierarchical scaling. I conclude with an extention of the theory to include magnetic fields. This latter theory represents an alternative to the more conventional dynamo theory.

scholarly journals Shape-Memory-Recovery Characteristics of Microcellular Foamed Thermoplastic Polyurethane

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 351
Author(s):  
Chang-Seok Yun ◽  
Joo Seong Sohn ◽  
Sung Woon Cha
Keyword(s):  
Shape Memory ◽  
Cell Density ◽  
Shape Recovery ◽  
Structural Changes ◽  
Thermoplastic Polyurethane ◽  
Testing Machine ◽  
Base Material ◽  
Memory Mechanism ◽  
Foaming Process ◽  
Dog Bone

We investigated the shape-recovery characteristics of thermoplastic polyurethane (TPU) with a microcellular foaming process (MCP). Additionally, we investigated the correlation between changes in the microstructure and the shape-recovery characteristics of the polymers. TPU was selected as the base material, and the shape-recovery characteristics were confirmed using a universal testing machine, by manufacturing dog-bone-type injection-molded specimens. TPUs are reticular polymers with both soft and hard segments. In this study, we investigated the shape-memory mechanism of foamed polymers by maximizing the shape-memory properties of these polymers through a physical foaming process. Toward this end, TPU specimens were prepared by varying the gas pressure, foaming temperature, and type of foaming gas in the batch MCP. The effects of internal structural changes were investigated. These experimental variables affected the microstructure and shape-recovery characteristics of the foamed polymer. The generated cell density changed, which affected the shape-recovery characteristics. In general, a higher cell density corresponded to a higher shape-recovery ratio.

A fractal continuum model of the pulmonary arterial tree

1992 ◽  
Vol 72 (6) ◽  
pp. 2225-2237 ◽  
Author(s):  
G. S. Krenz ◽  
J. H. Linehan ◽  
C. A. Dawson
Keyword(s):  
Fractal Structure ◽  
Cumulative Distribution ◽  
Total Resistance ◽  
Arterial Tree ◽  
Vascular Volume ◽  
Capillary Bed ◽  
Pulmonary Arterial ◽  
Self Similar ◽  
The Mean ◽  
Level Order

The extant morphometric data from the intrapulmonary arteries of dog, human, and cat lungs produce graphs of the log of the vessel number, (N) or length (l) in each level vs. the log of the mean diameter (D) in each level that are sufficiently linear to suggest that a scale-independent self-similar or fractal structure may underlie the observed relationships. These data can be correlated by the following formulas: Nj = a1Dj-beta 1, and lj = a2Dj beta 2, where j denotes the level (order or generation) number measured from the largest vessel at the entrance to the arterial tree to the smallest vessel at the entrance to the capillary bed. With the hemodynamic resistance (R) represented by Rj = 128 microliterj/(Nj pi Dj4) and the vascular volume (Q) by Qj = Nj pi Dj2lj/4, the continuous cumulative distribution of vascular resistance (Rcum) vs. cumulative vascular volume (Qcum) (where Rcum and Qcum represent the total resistance or volume, respectively, upstream from the jth level) can be calculated from [formula: see text] where r = Dj/Dj+1 is a constant independent of j. Analogous equations are developed for the inertance and compliance distributions, providing simple formulas to represent the hemodynamic consequences of the pulmonary arterial tree structure.

ON THE FRACTAL STRUCTURE OF ELECTRON AVALANCHES

Fractals ◽  
1993 ◽  
Vol 01 (04) ◽  
pp. 939-946 ◽  
Author(s):  
Z. DONKÓ ◽  
I. PÓCSIK
Keyword(s):  
Fractal Dimension ◽  
Power Law ◽  
Inelastic Collision ◽  
Fractal Structure ◽  
Secondary Electrons ◽  
Electron Multiplication ◽  
Helium Gas ◽  
Self Similar ◽  
Collision Processes ◽  
Electron Avalanches

The motion of electrons in helium gas in the presence of a homogeneous external electric field was studied. Moving between the two electrodes, the electrons participate in elastic and inelastic collision processes with gas atoms. In ionizing collisions, secondary electrons are also created and in this way self-similar electron avalanches build up. The statistical distribution of the fractal dimension and electron multiplication of electron avalanches was obtained based on the simulation of a large number of electron avalanches. The fractal dimension shows a power-law dependence on electron multiplication with an exponent of ≈0.33.

scholarly journals Study on tumor cell RNA cross-anticancer mechanism in non-tumor mice experimental model

2018 ◽  
Author(s):  
Qiwang Xu
Keyword(s):  
Tumor Cell ◽  
Fractal Structure ◽  
Basic Research ◽  
Tissue Response ◽  
Biological Behavior ◽  
Cross Resistance ◽  
Specific Procedure ◽  
Anticancer Mechanism ◽  
Self Similar ◽  
Play Action

ABSTRACTTo report the experiments of fractal structure and self-similar function in biological coupled oscillation brings life system waving growth in life organism. At the same time by self-organization the system openness come into being to maintain stability features of growth survival. From this, the orderly oscillation of tumor cell RNA was recognized that this process could lead to system sequentiality openness. According to waving growth of basic research the procedure could be sure to turn into a model as out of control of growing in tumor. Then in complete contrast that derived from the same component which have cross resistance effect. It shows that its biological behavior is converted as only a single physical power to play action by inactivated processing. Subsequent further confirms the essential roles whether essential roles link up with recovery of physiological function. The result in that it could exhibit feature of anticancer owing to be endowed tissue embryonization response. So that it also exerts preventing on senile chronic diseases. In theory, the concept of this tissue response in life organism closely link up with the single physical power of RNA component so as to bring up specific procedure of growing and subsisting that deal with keeping life vigor generalized explanatory.

scholarly journals Analysis of the Process Parameters for Obtaining a Stable Electrospun Process in Different Composition Epoxy/Poly ε-Caprolactone Blends with Shape Memory Properties

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 475 ◽  
Author(s):  
Alvaro Iregui ◽  
Lourdes Irusta ◽  
Loli Martin ◽  
Alba González
Keyword(s):  
Shape Memory ◽  
Flow Rate ◽  
Composition Dependence ◽  
Fiber Diameter ◽  
Stable Process ◽  
Solution Concentration ◽  
Diglycidyl Ether ◽  
Process Variables ◽  
Shape Memory Properties

In this work Poly ε-caprolactone (PCL)/ Diglycidyl ether of bisphenol A (DGEBA) blends were electrospun and the obtained mats were UV cured to achieve shape memory properties. In the majority of studies, when blends with different compositions are electrospun, the process variables such as voltage or flow rate are fixed independently of the composition and consequently the quality of the fibers is not optimized in all of the range studied. In the present work, using the design of experiments methodology, flow rate and voltage required to obtain a stable process were evaluated as responses in addition to the fiber diameter and shape memory properties. The results showed that the solution concentration and amount of PCL played an important role in the voltage and flow rate. For the shape memory properties excellent values were achieved and no composition dependence was observed. In the case of fiber diameter, similar results to previous works were observed.

Investigating the Roles of Crystallizable and Glassy Switching Segments within Multiblock Copolymer Shape-Memory Materials

MRS Advances ◽  
2018 ◽  
Vol 3 (63) ◽  
pp. 3741-3749
Author(s):  
Wan Yan ◽  
Liang Fang ◽  
Ulrich Noechel ◽  
Oliver E. C. Gould ◽  
Marc Behl ◽  
...  
Keyword(s):  
Shape Memory ◽  
Tensile Tests ◽  
Multiblock Copolymers ◽  
Molecular Architecture ◽  
Memory Mechanism ◽  
Multiblock Copolymer ◽  
Relationship Of ◽  
Synergistic Relationship ◽  
Vapor Treatment ◽  
Insight Into

ABSTRACTThe variation of the molecular architecture of multiblock copolymers has enabled the introduction of functional behaviour and the control of key mechanical properties. In the current study, we explore the synergistic relationship of two structural components in a shape-memory material formed of a multiblock copolymer with crystallizable poly(ε-caprolactone) and crystallizable poly[oligo(3S-iso-butylmorpholine-2,5-dione)] segments (PCL-PIBMD). The thermal and structural properties of PCL-PIBMD films were compared with PCL-PU and PIBMD-PU, investigated by means of DSC, SAXS and WAXS measurements. The shape-memory properties were quantified by cyclic, thermomechanical tensile tests, where deformation strains up to 900% were applied for programming PCL-PIBMD films at 50 °C. Toluene vapor treatment experiments demonstrated that the temporary shape was fixed mainly by glassy PIBMD domains at strains lower than 600%, with the PCL contribution to fixation increasing to 42±2% at programming strains of 900%. This study into the shape-memory mechanism of PCL-PIBMD provides insight into the structure-function relation in multiblock copolymers with both crystallizable and glassy switching segments.

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