INTRODUCTION polyster

INTRODUCTION
Polyester fiber, specifically poly(ethylene terephthalate) (PET), is the largest volume synthetic
fiber produced worldwide. The total volume produced in 2002 was 21 million metric tons or
58% of synthetic fiber production worldwide. The distribution of synthetic fiber production
by chemistry is shown in Figure 1.1 [1].
If one assumes the total production is a single 5 denier per filament (dpf) (~20 mm in
diameter) filament, the total length would be about 0.01 light years (~1014 m) or the
equivalent of about one million trips to the moon. While other polyesters are commercially
produced in fiber form—poly(ethylene naphthalate) (PEN); poly(butylene terephthalate)
(PBT); poly(propylene terephthalate) (PPT); and poly(lactic acid) (PLA); thermotropic polyester
(liquid crystalline polymer (LCP)—these are of insignificant volume compared to PET.
Hence this chapter focuses primarily on PET.
The reasons for the dominating success of PET fiber are:
. Low cost
. Convenient processability
. Excellent and tailorable performance







The basis of the low cost lies in the high efficiency of the conversion of mixed xylenes to
terephthalic acid, the melting temperature (2808C) being well within the range of commercial
heating fluids, and the glass transition temperature (758C), allowing the convenient stabilization
of spinline- or drawline-introduced morphology and molecular orientation. The excellent
performance results from the ability to accurately control fiber morphology (distribution and
connectivity of crystalline and noncrystalline load-bearing units), allowing the balance of
thermal and dimensional stabilities, transport, and mechanical properties to be controlled.
Over the decades, since its introduction in the 1960s, polyester technology has evolved into a
large number of products that range from cotton-blendable staple to high-performance tire
cord. It is likely that PET will continue to dominate as the synthetic fiber of choice in future,
although profitability has constantly eroded with time and production has shifted from the
United States and Europe to Asia.
Polyester fibers have been reviewed in many publications [2–4], most recently by East [5],
and the reader is directed to these publications for additional details. This work provides the
reader with an overview of polyester fiber technology, sufficient to allow the vast and detailed
open and patent literature related to polyester fibers generally, and PET fiber specifically, to
become more meaningful.
1.2 PET HISTORY
The development of PET fiber began with the pioneering work on condensation polymers led
by W.H. Carothers of DuPont in the 1930s [6].
Carothers focused on aliphatic polyesters and the resulting properties were poor compared
to the aliphatic nylons that were simultaneously explored by his group. Much improved fiber
performance was achieved in the early 1940s by the team comprising Whinfield and Dickson
[7], Calico Printers Association Laboratory in Great Britain. Their work focused on aromatic–
aliphatic polyesters from terephthalic acid (TA) and ethylene glycol. The same studies examined
other aliphatic–aromatic polyester compositions, including PBT, PPT, and PEN. Commercialization
of PET was rapid after World War II with the introduction of Terylene in Great
Britain by ICI and the introduction of Dacron in the United States. Other products soon
followed and PET successfully entered the textile market as both filament yarn and staple, and
the industrial market as a rubber reinforcement filament yarn, primarily for use in the sidewalls
of passenger car tires. Key properties were wash-and-wear characteristics in textiles and high
modulus, coupled with excellent modulus retention, in industrial applications. The detailed
review of Brown and Reinhart [8] described this history.

The Rupp Report: GITEC Grosse Back On Track

Jürg Rupp, Executive Editor In anticipation of the forthcoming ITMA in Barcelona, Spain, the Rupp Report is taking acloser look at some exhibitors that will take part in the exhibition in Catalonia's capital city. Here is the first story: At ITMA 1999 in Paris, there was an exhibit in the booth of Germany-based Grosse Jac Webereimaschinen GmbH that had never before been seen: a UniShed Jacquard machine that did not have a harness. It was one of the very few sensations in Paris. After that, not much followed. Now the company has come back to the surface under anew name. The Rupp Report interviewed Dr. Roberta Boscoli, sales director of GITEC Grosse Internationale Technologie GmbH,about the future of the company. Grosse was founded 1878 in Greiz, in the eastern part of Germany. Over time, the companybecame one of the leading producers of mechanical Jacquard machines, offered under the Unirapid name. And, asmentioned above, the company introduced the UniShed harnessless Jacquard machine in 1999. However, after that event in Paris, the company somewhat disappeared from the markets. Quite unnoticed by the public, Grosse was taken over in 2005 by China-based Hisun Group Co. Ltd., which consequently led to the establishment of GITEC GrosseInternationale Technologie GmbHin Ulm-Lehr in southern Germany,as a daughter company of the Hisun Group. Same Expertise Today, GITEC Grosse is in the same business as before: the company produces electronic Jacquard machines in sizes ranging from 1,344 up to 12,000 hooks. Potential users are the traditional weaving mills producing a broad range of products, including home textiles,as well as producers of industrial fabrics. Ninety-five percent of all products are exported - at the moment, mainly to China, India and Turkey. Furthermore, its product line includes the latest generation of harnessless Jacquard machines, the UniShed 2 for the production of airbag fabrics. This optimized model will be shown in Barcelona. Boscoli said the company is working with a kind of cluster network in the global textile regions, such as China, India and other regions. In the clusters, field representatives are in constant contact with the customers, but also GITEC Grosse staff in the respective countries are taking care of the customers, supported by the field personnel. Markets Boscoli mentioned that the current market is recovering aftera time of recession. The companyis enjoying an increasing numberof inquiries from Europe and North America for technical fabrics applications. However, the current bestseller inthe program is the electronic Jacquard machine EJT-4, which is especially suitable for terry fabrics. Thanks to some particularfeature,s the machine produces an even pile surface, which is claimed to deliver a very good terry fabric quality. For standard products, there is a great deal of competition among producers, Boscoli said, mainly with cheap products from China. In the high-level segments, she claims there are no problems, thanks to GITEC Grosse's unique products. ITMA Barcelona As GITEC Grosse is also an originalequipment manufacturer, there will be a few products seen in thebooth of its China-based sister company Zhejiang Grosse Precision Machinery Co. Ltd.; in Japan-based Tsudakoma Corp.'s booth, which will be showing a UniShed 2; and in the booth of Italy-based Smit Textile S.p.A., which will display an EJP-4 on a rapier weaving machine. The expectations of the new old company are high: to consolidateits market presence, winning new customers, but also to confirm some trends relating to the new UniShed 2 for airbags. The Future Regarding developments in the near future, the clear vision is to gain more application areas for the UniShed 2; mainly for industrial fabrics and top-level products. This goes in line with the targets for the next few years: further increase in market share; market implementation of the UniShed; and, on top of all, Boscoli said, re-establishment of the Grosse brand. And how does Boscoli see the future? "I am certain that the Indian market will experience an upgrade of the machinery technology for standard products. Europe and North America will slightly assert their market lead in the segment of technical textiles - but these regions have to be aware of China: That country will soon become an important player in this segment," she said. August 16, 2011 Advertisement

Textile News ‎ Karl Mayer Offers Indig-O-Matic System Based On Clariant's Advanced Denim Dyeing Germany-based Karl Mayer Textilmaschinenfabrik GmbH has revamped its Indig-O-Matic modular warp yarn preparation system for denim weaving to integrate Switzerland-based specialty chemical company Clariant International Ltd.'s Pad/ Sizing Ox dyeing technology that is part of Clariant's Advanced Denim dyeing concept. According to Clariant, the Advanced Denim process, which may be used with existing mill equipment, enables reduction of the number of boxes used in conventional dyeing from 12 to one and cuts water consumption by up to 92 percent, with minimal wastewater generation; energy consumption by up to 30 percent; and cotton waste by up to 87 percent compared with conventional slasher dyeing processes. The Advanced Denim concept was based on ... More in textileworld.com

The Rupp Report: A Nightmare Or A Break?

Investigation of the figure of merit for filters with a single n

Jing Wang^{, a,} , Seong Chan Kim^a and David Y.H. Pui^a

^aParticle Technology Laboratory, Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, USA

Received 7 June 2007; 

revised 14 September 2007; 

accepted 4 December 2007. 

Available online 8 December 2007.

Abstract

We investigate filters composed of a layer of nanofibers on a substrate made of micrometer fibers and compare the performance of such nanofiber media to conventional micrometer fibrous filters. The performance of the nanofiber filters is evaluated using the figure of merit, which represents the ratio between the filtration efficiency and the pressure drop. Filtration tests were performed on four samples with different nanofiber solidities. As the nanofiber solidity increases, the filtration efficiency and the pressure drop both increase. We develop a numerical model to simulate the nanofiber filters. When the nanofiber solidity is appropriately adjusted, the pressure drop computed from the model is in good agreement with experimental results. Filtration efficiency for the nanofibers due to interception, inertial impaction and diffusion can be computed from the model. The simulation results are in good agreement with experiments for 20–780 nm particles but discrepancies exist for particles smaller than 20 nm. Our results show that nanofiber filters have better figure of merit for particles larger than about 100 nm compared to conventional fiberglass filters. For particles smaller than 100 nm, nanofiber filters do not perform better than conventional fiberglass filters.

Keywords: Nanofiber filters; Figure of merit