Fiber length reduction during shearing in polymer processing

2017 ◽  
Author(s):  
Elmar Moritzer ◽  
Gilmar Heiderich
Keyword(s):  
Fiber Length ◽  
Polymer Processing ◽  
Length Reduction

scholarly journals Fiber length reduction during injection molding

2019 ◽  
Author(s):  
Elmar Moritzer ◽  
Gilmar Heiderich ◽  
Andre Hirsch
Keyword(s):  
Injection Molding ◽  
Fiber Length ◽  
Length Reduction

scholarly journals Improving Mechanical Textile Recycling by Lubricant Pre-Treatment to Mitigate Length Loss of Fibers

2020 ◽  
Vol 12 (20) ◽  
pp. 8706
Author(s):  
Katarina Lindström ◽  
Therese Sjöblom ◽  
Anders Persson ◽  
Nawar Kadi
Keyword(s):  
Fiber Length ◽  
Woven Fabrics ◽  
Test Method ◽  
Rotor Spinning ◽  
Tensile Tester ◽  
Peg 4000 ◽  
Textile Recycling ◽  
Pre Treatment ◽  
Recycled Fibers ◽  
Length Reduction

Although there has been some research on how to use short fibers from mechanically recycled textiles, little is known about how to preserve the length of recycled fibers, and thus maintain their properties. The aim of this study is to investigate whether a pre-treatment with lubricant could mitigate fiber length reduction from tearing. This could facilitate the spinning of a 100% recycled yarn. Additionally, this study set out to develop a new test method to assess the effect of lubricant loading. Inter-fiber cohesion was measured in a tensile tester on carded fiber webs. We used polyethylene glycol (PEG) 4000 aqueous solution as a lubricant to treat fibers and woven fabrics of cotton, polyester (PES), and cotton/polyester. Measurements of fiber length and percentage of unopened material showed the harshness and efficiency of the tearing process. Treatment with PEG 4000 decreased inter-fiber cohesion, reduced fiber length loss, and facilitated a more efficient tearing process, especially for PES. The study showed that treating fabric with PEG enabled rotor spinning of 100% recycled fibers. The inter-fiber cohesion test method suggested appropriate lubricant loadings, which were shown to mitigate tearing harshness and facilitate fabric disintegration in recycling.

scholarly journals Influences on Textile and Mechanical Properties of Recycled Carbon Fiber Nonwovens Produced by Carding

2021 ◽  
Vol 5 (8) ◽  
pp. 209
Author(s):  
Frank Manis ◽  
Georg Stegschuster ◽  
Jakob Wölling ◽  
Stefan Schlichter
Keyword(s):  
Mechanical Properties ◽  
Carbon Fibers ◽  
Fiber Length ◽  
Product Life Cycle ◽  
Energy Savings ◽  
Bending Strength ◽  
Process Chain ◽  
Fiber Volume ◽  
Four Point Bending ◽  
Length Reduction

Nonwovens made of recycled carbon fibers (rCF) and thermoplastic (TP) fibers have excellent economic and ecological potential. In contrast to new fibers, recycled carbon fibers are significantly cheaper, and the CO2 footprint is mostly compensated by energy savings in the first product life cycle. The next step for this promising material is its industrial serial use. Therefore, we analyzed the process chain from fiber to composite material. Initially, the rCF length at different positions during the carding process was measured. Thereafter, we evaluated the influence of the TP fibers on the processing, fiber shortening, and mechanical properties. Finally, several nonwovens with different TP fibers and fiber volume contents between 15 vol% and 30 vol% were produced, consolidated by hot-pressing, and tested by four-point bending to determine the mechanical values. The fiber length reduction ranged from 20.6% to 28.4%. TP fibers cushioned the rCF against mechanical stress but held rCF fragments back due to their crimp. The resulting bending strength varied from 301 to 405 MPa, and the stiffness ranged from 16.3 to 30.1 GPa. Design recommendations for reduced fiber shortening are derived as well as material mixtures that offer better homogeneity and higher mechanical properties.

Observing the relaxation of molecular orientation in sheared liquid crystalline polymer solutions

1990 ◽  
Vol 48 (4) ◽  
pp. 1092-1093
Author(s):  
Wendy Putnam ◽  
Christopher Viney
Keyword(s):  
Molecular Orientation ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Processing ◽  
Molecular Alignment ◽  
Global Alignment ◽  
Shear Direction ◽  
Axial Strength ◽  
Strength And Stiffness

Liquid crystalline polymers (solutions or melts) can be spun into fibers and films that have a higher axial strength and stiffness than conventionally processed polymers. These superior properties are due to the spontaneous molecular extension and alignment that is characteristic of liquid crystalline phases. Much of the effort in processing conventional polymers goes into extending and aligning the chains, while, in liquid crystalline polymer processing, the primary microstructural rearrangement involves converting local molecular alignment into global molecular alignment. Unfortunately, the global alignment introduced by processing relaxes quickly upon cessation of shear, and the molecular orientation develops a periodic misalignment relative to the shear direction. The axial strength and stiffness are reduced by this relaxation.Clearly there is a need to solidify the liquid crystalline state (i.e. remove heat or solvent) before significant relaxation occurs. Several researchers have observed this relaxation, mainly in solutions of hydroxypropyl cellulose (HPC) because they are lyotropic under ambient conditions.

Degassing during polymer processing

2002 ◽  
Author(s):  
Ingo Gestring ◽  
Dieter Mewes
Keyword(s):  
Polymer Processing

Survey of Relations of Chemical Constituents in Polymer-Based Materials with Brittleness and its Associated Properties

2016 ◽  
Vol 10 (4s) ◽  
pp. 595-600 ◽  
Author(s):  
Witold Brostow ◽  
◽  
Haley E. Hagg Lobland ◽  
Keyword(s):  
Chemical Composition ◽  
Impact Strength ◽  
Free Volume ◽  
Chemical Constituents ◽  
Polymer Processing ◽  
Brittle Behavior ◽  
Composition And Structure ◽  
Common Thread

The property of brittleness for polymers and polymer-based materials (PBMs) is an important factor in determining the potential uses of a material. Brittleness of polymers may also impact the ease and modes of polymer processing, thereby affecting economy of production. Brittleness of PBMs can be correlated with certain other properties and features of polymers; to name a few, connections to free volume, impact strength, and scratch recovery have been explored. A common thread among all such properties is their relationship to chemical composition and morphology. Through a survey of existing literature on polymer brittleness specifically combined with relevant reports that connect additional materials and properties to that of brittleness, it is possible to identify chemical features of PBMs that are connected with observable brittle behavior. Relations so identified between chemical composition and structure of PBMs and brittleness are described herein, advancing knowledge and improving the capacity to design new and to choose among existing polymers in order to obtain materials with particular property profiles.

Estimation of the Mean Fiber Length of Individual Grease Fleeces

1968 ◽  
Vol 27 (5) ◽  
pp. 1224
Author(s):  
Walter R. Harvey ◽  
Mary E. Hourihan ◽  
Clair E. Terrill
Keyword(s):  
Fiber Length ◽  
The Mean
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