Polyester Technology
polyester-technology: Slides from presentation by Mr. Zainul Abideen, SDM (Product Development), Gatron Industries
Electrospinning
In the electrospinning process a high voltage is used to create an electrically charged jet of polymer solution or melt, which dries or solidifies to leave a polymer fiber. One electrode is placed into the spinning solution/melt and the other attached to a collector. Electric field is subjected to the end of a capillary tube that contains the polymer fluid held by its surface tension. This induces a charge on the surface of the liquid. Mutual charge repulsion causes a force directly opposite to the surface tension. As the intensity of the electric field is increased, the hemispherical surface of the fluid at the tip of the capillary tube elongates to form a conical shape known as the Taylor cone. With increasing field, a critical value is attained when the repulsive electrostatic force overcomes the surface tension and a charged jet of fluid is ejected from the tip of the Taylor cone. The discharged polymer solution jet undergoes a whipping process wherein the solvent evaporates, leaving behind a charged polymer fiber, which lays itself randomly on a grounded collecting metal screen. In the case of the melt the discharged jet solidifies when it travels in the air and is collected on the grounded metal screen. [http://www.che.vt.edu/Wilkes/electrospinning/electrspinning.html]
Note: To avoid confusion ignore the figure on electrospinning from the above source. Instead, here is a link to a better, and more easy to understand diagram.
Spider Silk
Here’s a link to the youtube video we saw and discussed in class showing the spinning of spider silk from the milk of genetically modified goats.
Ok so here they are. The last few remaining notes and handouts for this course.
I’m posting the material on proteinic fibres, synthetic fibres and fibres for technical textiles. Here are the slides we discussed in class along with the primary reference source to study from to understand the transitions that would otherwise look like jargon to those who weren’t there in class. (more…)
Time now to look at cotton along with other forms of regenerated cellulosic fibres which we discussed in class that include, Viscose Rayon, High Wet Modulus Viscose (Modal) and Lyocell. (more…)
Finally… I’ve managed to put something together to post online for you people to go through. Although I’ve been telling in class time and again which pages from which book need to be referred to, here’s a more elaborate description of what needs to be studied. (more…)
The first class on this particular topic was a facilitated learning session in which the sections were divided into 4 groups and each was given a task to look into of the following tasks. Each group was required to try and figure out how they could find out the following properties of textile fibres.
Before looking into this, the first question that arises is why one would want to do any of this. Although I threw some pointers here and there throughout each of the sessions regarding this, for now I’m going to leave this point open to discussion and see what you people come up with.
The third lecture in the fibre science series dealt chiefly with fiber formation theories. These theories are discussed in Physical Properties of Textile Fibres from page 25-32. Another excellent resource to study these theories is the macrogalleria’s crystallinity page.
I had mentioned in my previous notes that this lecture will primarily comprise of material from the first 37 pages of Physical Properties of Textile Fibres.
During these lectures, there will be a reasonable amount of meandering as the complexity in the subject matter will force us to look back at matter discussed in previous discussions. There is absolutely no harm in this, as long as the general progress is forward and a sound understanding of fundamental concepts is developed.
This introductory lecture is meant to bring the class to a common wavelength so future understanding of the course is built on coherent concepts. Fibres, are defined by the Textile Institute as units of matter characterized by flexibility, fineness and a high ratio of length to thickness (refer to Textile Terms and Definitions).
Thus by the definition lots of things, wires, muscle fibres, wood fibres fit into this category. However, not all of them are suited for use as textiles. When considering textiles there are some other properties that come into play. For instance, a minimum breaking strength may be required, some degree of thermal stability and extensibility may be needed for a fiber to be of any use.
With advancements in technology fibers and fiber science are reaching new frontiers. The development of electro-spinning for instance, enabling the spinning of extremely fine fibers with thicknesses of a few 10s to 100 nanometers has paved way to many previously non conceivable materials to be used as fibres. Materials like carbon nanotubes, used as high strength, light weight, reinforcement for a variety of applications and ceramic fibres developed into electro-spun non woven material are examples of such developments.
