m 

E. I. du Pont de Nemours and Mohawk Industries, Inc. PTT Poly Canada 

Company 

 September 7, 2006 

Office of Secretary 

Federal Trade Commission 

600 W. Pennsylvania Ave., NW 

Washington, DC 20580 

Revised Petition To Establish A New Generic Subclass 

Mohawk Industries, Inc.1 (Mohawk), E. I. du Pont de Nemours and Company2 (DuPont), and 

PTT Poly Canada3 (PTT Canada) (collectively “Petitioners”) hereby submit this Revised 

Petition to the Federal Trade Commission (the “Commission”) for the establishment of a new 

generic subclass within the existing polyester category for fibers made from poly(trimethylene 

terephthalate) (“PTT”) to restate and supplement the contents of the Petition dated February, 

21, 2006 in order to address certain questions raised by the Commission. Petitioners note the 

Commission’s April 18, 2006 action taken in response to the February 21, 2006 Petition 

assigning the designation “PTT001” for PTT fiber for temporary use until a final 

determination is made by the Commission as to the merits of this Petition. Petitioners 

propose in order of preference the following names for a new generic subclass of polyester 

that may be used with respect to PTT fibers: 1. triexta; 2. resisoft; and 3. durares. 

1

 Mohawk was founded more than 120 years ago and today is the leading producer and distributor of flooring 

worldwide. Mohawk products serve all major flooring categories: carpet, rugs, hardwood, laminate, ceramic tile, 

and vinyl flooring. Mohawk has launched a line of carpets manufactured from PTT and sells such carpets under 

the trademark SmartStrand. 

2

 Founded in 1802, DuPont is a science company operating in more than 70 countries. DuPont offers a wide 

range of innovative products and services for markets including agriculture, nutrition, electronics, 

communications, safety and protection, home and construction, transportation and apparel. DuPont markets PTT 

under the trademark Sorona®. 

3

 PTT Poly Canada is a 50 / 50 Limited Partnership between Shell Chemicals Canada LTD and SGF Chimie, a 

subsidiary of Societe Generale de Financement du Quebec (SGF). PTT Poly Canada markets PTT under the 

trademark Corterra® Polymers. 
Summary of Petition 

Petitioners seek to establish a generic subclass for fibers spun from PTT on the grounds that 

such fibers satisfy the three tests required by the Commission for the use of a generic 

subclass.4

 These tests are satisfied by fibers spun from PTT because: 

1. PTT fiber has the same general chemical composition as the Commission’s established 

polyester generic fiber category. 

2. PTT fiber, while having the general chemical composition of polyester, has distinctive 

properties of importance to the general public as a result of its unique chemistry, 

molecular design, and fiber structure. These properties are durability, resilience, 

softness, and stretch with recovery. 

PTT fiber’s distinctive features of durability, resilience, softness, and stretch with recovery 

make PTT fiber suitable for uses which conventional polyester (PET) is significantly less well 

suited. These features are as follows: 

a) Carpet applications: Durability and softness. 

b) Apparel applications: Softness and stretch with recovery. 

Fiber Attributes Of Importance In Markets Where PTT Fiber Is Used 

An important issue in an application for a generic subclass is the requirement that the 

distinctive features of any new polymer or fiber be important to the general public, and that 

such features make the fiber suitable for uses for which other fibers which fall under the 

established generic name are not suited, or would be significantly less well suited. 

Since the distinctive features of a fiber may differ from application to application, it is useful 

to first discuss the two fiber markets where fibers made from PTT are used so that the 

properties of PTT can be compared to the properties of the other polyester that is used for 

fiber applications. These markets are apparel and residential carpet. In these markets, the 

form of polyester that is most widely used is poly(ethylene terephthalate) (“PET”). 

Accordingly, Petitioners will provide data comparing the chemistry and crystalline structure 

4

 These factors were identified as follows by the Commission in its Notice of Proposed Rulemaking of February 

15, 2002 appearing at 67 FR 7104: 

“Thus, a new generic fiber subclass may be appropriate in cases where the proposed subclass fiber: (1) Has the 

same general chemical composition as an established generic fiber category; (2) has distinctive properties of 

importance to the general public as a result of a new method of manufacture or substantially differentiated 

physical characteristics, such as fiber structure; and (3) the distinctive feature(s) make the fiber suitable for uses 

for which other fibers under the established generic name would not be suited, or would be significantly less well 

suited.” 

2
of PTT to PET and the performance of fibers made from these polymers in carpet and apparel 

applications.

5 

Residential Carpet 

Prior to the launch of residential carpet made from PTT by Mohawk Industries, Inc. and Shaw 

Industries, Inc. (the two largest United States suppliers of carpet for the residential market), 

the four principal types of man-made fiber used to manufacture carpet were nylon, PET 

polyester, and polypropylene. Of these four materials, nylon carpet offered the broadest range 

of attributes most highly valued by consumers. As a result, for comparable carpet 

constructions, nylon carpet has commanded the highest price. Carpet made from PET has 

been less highly regarded because PET fiber lacks the durability and resilience of nylon and 

because, compared to many recent nylon carpet constructions, PET fibers were less flexible 

and not as soft as some nylon constructions. 

With the launch of carpet based on PTT, consumers have a choice of a fiber that has stain 

resistance properties superior to nylon, together with durability, resilience and softness that 

matches the highest quality constructions of nylon residential carpet. 

In a 2004 study of consumer purchasing preferences6, 1600 consumers between 25 and 64 

years of age who shopped for carpet in the past were asked questions pertaining to carpet fiber 

performance and preferences. A list of those carpet attributes that relate to fiber performance 

and the percentages of consumers who rated the attribute as very important is in Table 1 

below. The attributes where PTT fiber has a significant performance advantage in residential 

applications over PET fiber because of its physical and chemical properties are highlighted in 

bold italics. 

Table 1: Consumer preferences in carpets 

Attribute Percentage Rating Attribute As Very Important 

Common spills and pet accidents can be removed 

easily even after they have dried 

69% 

The carpet will stand up to years of foot traffic 

without matting down 

67% 

Dirt and soil can be removed easily from the carpet 

with regular vacuuming 

66% 

Areas where spills have been cleaned will not be 

visible 

64% 

5 In addition, Petitioners will provide data comparing the performance of PTT in carpet applications to the 

performance of nylon carpet because nylon currently has the largest market share in residential carpet. 

Accordingly, the properties of nylon fibers are a useful reference to define those features of PTT carpet fibers 

that are of importance to the general public. 

6

 Data taken from a August 23, 2004 study titled Carpet Fiber Performance and Preferences prepared for 

Mohawk Industries by the Brandware Group. 

3 
Stain resistant properties will not diminish over the 

life of the carpet 

63% 

Soil resistance properties will not diminish over the 

life of the carpet 

61% 

The pile of the carpet stays tight and will stand up 

like new after normal vacuuming 

58% 

The color of the carpet will stay the same year after 

year and never fade, even in direct sunlight 

56% 

Heavy soil and most stains can be removed from 

the carpet with just plain water 

53% 

The carpet pile will not shed or fuzz 53% 

The carpet is soft and comfortable to sit on or lie 

on 

49% 

The carpet can be professionally cleaned as often 

as you want 

36% 

The carpet never shows tracks from footprints or 

vacuuming 

27% 

The carpet will never produce static shock, even if 

you walk on it in wool socks 

24% 

Apparel 

There are many man-made fibers used in the apparel industry, and the supply chain is far 

more complex than in the carpet industry. However, it is still possible to obtain market 

requirements information thru a carefully designed “voice of customer” process by 

interviewing fabric buyers and brand managers in the apparel industry. These steps in the 

supply chain determine what fabrics are made into garments for the consumer public. Fabric 

buyers and brand managers understand the downstream requirements and must match that 

demand to the supply of fabrics and in turn what polymers and fibers are used in those fabrics. 

In order to understand these preferences, DuPont conducted a survey7 of downstream 

participants in the supply chain to determine preferences in the apparel supply chain where 

differences in fabric fiber content were important and discernable. Table 2 lists the 

companies that were surveyed in the countries which are the major sources of fabrics made 

from man-made fibers. The purpose of the survey was to determine the attributes of fabrics 

that are of greatest importance to consumers. 

7

 This study was conducted by DuPont employees in the first and second quarter of 2004. 

4
5

Boxplots of Importan by Attribut

(means are indicated by solid circles)

Table 2: Apparel fabric preferences survey participants 

Country Fabric Producer or Purchaser 

Korea Li & Fung, C&A/Mondial, Sears, SAE-A 

Trading Company, Mastex, Liz Claiborne, 

Mast Industries 

Taiwan Esquel, Levi, TAL, Adidas, Li & Fung, 

Nike, Puma, Eddie Bauer 

China Burringtex, Liz Claiborne, Federated, May 

Co., Mast, Newtimes Jones (Jones New 

York) 

Survey participants were asked to rate the following attributes on a scale of 0 to 5. The results 

are shown in Figure 1 with the mean denoted by the small square and the range denoted by 

the box. The average of the responses is the horizontal line. 

1. Stretch 

2. Softness (also referred to as “Drape”) 

3. Easy Dye 

4. Easy Care 

5. Made from renewable resources 

6. Stain resistance 

7. Resilience 

8. Printability 

From this list of eight attributes, the three which had the greatest importance were easy care, 

softness (hand or drape), and stretch with recovery. PTT fiber is superior to PET fiber with 

Figure 1: Fabric survey results – Box represents 95% of questionnaire responses; 

red dot equals the numerical average of responses; horizontal line equals the mean of 

the responses; and vertical line equals high and low ranges of responses. 

0 

1 

2 

3 

4 

5 

Importance 

Attribute 

Care

Dye

Green

Prints

Resilience

Soft

Stain Res.

Stretch 
respect to two of these three attributes: softness and stretch with recovery. 

Discussion of Factors Needed For The Designation Of A New Generic 

Subclass For Fibers Spun From PTT Polymer 

Section 1. PTT polymer and fibers spun from PTT have the same general chemical 

composition as the FTC’s established polyester generic fiber category. 

Rule 7(c) defines "polyester" as "[a] manufactured fiber in which the fiber-forming substance 

is any long chain synthetic polymer composed of at least 85% by weight of an ester of a 

substituted aromatic carboxylic acid, including but not restricted to substituted terephthalate 

units, [formula omitted] and para substituted hydroxy-benzoate units, [formula omitted]." 16 

CFR 303.7(c). 

PTT polymer is made by reacting (a) dimethyl terephthalate (DMT) or terephthalic acid 

(TPA), both of which are substituted aromatic carboxylic compounds, and (b) 1,3-propanediol 

(PDO) to form a long chain synthetic polymer consisting of more than 85% of substituted 

terephthalate esters. Accordingly, fiber made from PTT polymer has the same chemical 

composition as is described by Rule 7(c). 

Section 2. PTT fiber, while having a chemical composition which causes it to fall within 

the definition provided for polyester set forth in 16 CFR 303.7(c), has distinctive 

properties of importance to the general public as a result of its unique chemistry, 

molecular design, and fiber structure. 

The generic class of aromatic polyesters today consists of several different chemical 

formulations including poly(ethylene terephthalate) (PET) and PTT. The type of polyester 

that is familiar to consumers because of its use in carpet and apparel applications is PET. 

However, the molecular differences between PET and PTT are quite profound, and result in 

significantly different physical properties of fibers. These properties are (a) 

durability/resilience for carpet applications, (b) softness for both consumer carpet and apparel 

applications, and (c) stretch and recovery for apparel applications. 

a) Durability/Resilience 

Fiber durability, which in carpet applications is measured by the resiliency of the fiber and its 

ability to recover from compression, is together with stain resistance the most important 

property that consumers look to when selecting a residential carpet as shown in the consumer 

survey results set forth above. This property is inherently better in fibers made from PTT vs. 

PET because of PTT’s chemistry and molecular design. PET and PTT crystallize into triclinic 

unit cells during fiber formation. However, the glycol portion of their chemical chains 

crystallizes into different conformations. The two methylene units in the glycol portion of 

PET are arranged trans to each other, whereas the three methylene units in PTT are arranged 

in a gauche-gauche conformation as shown in Figure 2 below: 

6
Figure 2. PTT molecule showing gauche-gauche Conformation (ref. 1) 

Because of the methylene diol’s conformations, PTT chains are contracted by 24.7% while 

the PET chain is fully extended. Also the benzene ring of the terephthalic ester groups of 

PET are oriented parallel to each other in every chemical repeating unit. However, the 

orientation of PTT’s benzene ring in the successive terephthalic ester units is at an angle to 

each other), thus PTT molecular chain forms a 2/1 helix, which is made up of two repeating 

units per turn which introduces a zigzag shape to the polymer chain. This difference is 

illustrated in Figure 3 which compares the molecular structures of PET and PTT. As a result 

of this structure, compressive forces translate at the molecular level to bending and twisting of 

bonds, rather than just stretching. The molecular structure of PTT is more like a coil spring 

compared to a straight wire structure in the case of PET polyester.8 Therefore, PTT fiber can 

take an additional level of applied strain and recover completely. 

8

 This property of PTT polymer has also been confirmed through study of x-ray diffraction patterns which occur 

when fibers of PTT are subjected to stress. See Crystal Deformation in Aromatic Polyester, Journal of Polymer 

Science, Vol. 13, 799-813 (1975) ref 2. 

7
Figure 3: Structural differences between PET and PTT (ref 3) 

Error! 

(a) (b) 

Arrangement of PET (a) and PTT (b) crystalline molecular chains. Arrow indicates 

the alignment direction of the benzene ring. 

Accordingly, when a PET fiber is subjected to compression forces in carpet applications (e.g., 

when carpet is walked on or subjected to carpet industry tests that simulate foot traffic), the 

molecular chain structure of PET changes and develops a larger permanent set or crystal 

deformation which is not completely recoverable. This causes consumer carpet made from 

PET polyester to develop a crushed appearance where the carpet fibers do not continue to 

stand up as they did when the PET carpet was new. 

In the case of PTT, compression forces in carpet applications cause the molecular chain 

structure to deform. However, the crystalline structure is able to recover without developing a 

permanent set. The carpet fibers continue to stand up and appear new for a significantly 

longer period of time. The basis for this performance difference is the molecular structure of 

the two polymers, extended to larger physical properties differences such as crimp retention 

as shown in Figure 4 below: 

8
Figure 4: Crimp recovery of PET and PTT BCF yarns (Shell internal study) % Crimp Recovery

100 

80 

60 

40 

20 

0 

0.00 0.50 1.00 1.50 

Tension, g/den. 

PET 

PTT 

b) Softness 

Softness is important to the consumer for both carpet and apparel applications. Consumers 

judge the softness of a residential carpet by touching or walking on the upright twisted fibers 

or yarns. The ease with which the yarns bend over is a measure of softness. Consumers 

judge the softness of a fabric by assessing its hand or drape (the ease with which conforms to 

the shape of the body). The degree of softness in both cases is proportional to the amount of 

force required to bend the fiber. The laboratory measurement of the amount of force required 

to bend a fiber is know as fiber modulus, which can also ascertain the relative softness of the 

resulting fabric or article. 

The lower modulus of PTT fibers over PET fibers is explained on a molecular level by the 

lower crystalline modulus of PTT. The odd number of carbon atoms in the tri-methylene 

constituent of PTT results in different chain conformations for PTT as compared to PET. 

PTT conformation is more helical or spring like, whereas PET is straighter like a wire. 

Naturally, more force is needed to deform a straight wire while very little force is required to 

deform a coil spring to the same extent, therefore, PTT with coil spring structure has a very 

low crystal modulus, 2.5 GPa vs. 107 GPa (ref 5) for PTT and PET crystals, respectively. 

As a result, the crystals of PTT are relatively weaker and easier to bend compared to PET, and 

the fiber made from this polymer has lower modulus. 

9
Evidence of this different crystalline modulus caused by molecular structure differences is 

apparent also in the higher glass transition temperatures (Tg) and crystalline melting 

temperatures (Tm) of PET vs. PTT. These higher temperatures generally correspond to stiffer 

molecular structures. See Table 3 below: 

Table 3: Differences in physical properties of PTT and PET (ref. 4) 

Physical properties of PTT vs. PET 

 PTT PET 

Tm (°C) 228 255 

Tg (° C) 50 75 

Young’s modulus is yet another measure of the relative hardness of a material, and from the 

data in Figure 5 it is readily apparent that PTT has far lower modulus than PET. 

made from PET, nylon 66, and PTT. This graph shows that the properties of PTT polymer 

result in fibers of PTT which have lower modulus than fibers made from either PET or nylon 

66. 

Figure 5. Young’s modulus of PET and PTT fibers (ref 5) 

Finally, Figure 6 shows a stress (force) vs. strain (fiber deformation) comparison of fibers 

10
Figure 6. Modulus of PET and PTT Fibers vs. Nylon 6,6 (ref 5) 

0 

1 

2 

3 

4 

5 

6 

Stress g/den.

N66 

PET 

PTT

0 10 20 30 40 50 

Strain, % 

As a result of the lower modulus of the PTT fibers, carpets made from PTT fibers are 

perceived to be softer, and apparel fabrics made from PTT fibers have greater softness and 

superior “hand”. 

(c) Stretch with Recovery 

Stretch and recovery of fiber is important in apparel applications in order to improve the 

comfort of garments and increase their ability to retain their shape and appearance. 

Elastic recovery is measured by first extending the fiber in a tensile tester to a given strain 

(percent of extension) and then holding the fiber at that position for a given time, after which 

time the strain is completely released. After a fixed period of relaxation time, the fiber is reextended and released to measure its recovery again. The difference between these two 

extensions and recoveries represents the immediate recoverability of the fiber and the 

permanent set. More elastic fibers recover immediately with lower permanent set. The 

terms are further defined in Figure 7. 

11
Figure 7. Elastic extension and recovery terminology (ref 5) 

As shown in Section 2(a) above, the crystalline region of the PET polymer will absorb only a 

limited amount of strain. Strain beyond that point will cause the fiber to deform irreversibly. 

In the case of PTT, the strain is absorbed by the crystal structure uncoiling like a spring. 

When the strain is released, the crystalline structure recovers. This difference is shown in 

Figure 8 which compares the stretch and recovery performance of PET and PTT fibers. The 

data indicates that PTT fiber can be stretched with total recovery more than five times the 

stretch after which PET fails to recover. 

12
Figure 8. Stretch with recovery of PET and PTT fibers (ref 5) 

PET 

PTT 

Section 3. The properties of fibers made from PTT described in Section 2 above cause 

PTT fibers to be suitable for carpet and apparel applications for which other fibers 

marketed under the established generic name polyester would be significantly less well 

suited. 

As discussed above, the attributes of durability/resilience and softness are of greater 

importance to consumers when purchasing residential carpet. For apparel applications, 

softness and stretch with recovery are among the most important attributes of any fabric. The 

test results set forth below illustrate the improved performance of PTT fibers over PET fibers 

with respect to these attributes. Each test is preceded by a description of the protocol, and the 

identity of the company performing the test. 

a) Durability/Resilience 

Carpet durability and resilience can be measured by a number of standard tests. For example, 

there are simple floor walking tests, where a sample of carpet is placed in a high traffic 

location and the number of walkers is simply counted using an electric eye trigger. Another 

13
Sorona

test, called the Hexapod Wear Test is an appearance retention test endorsed by the Carpet and 

Rug Institute (CRI). It follows a defined accelerated fatigue process developed through 

studies conducted by CRI’s Performance Standards Committee which simulates the most 

aggressive parts of a walking action. These samples’ appearance retention is then assessed 

according to a defined protocol vs. its "newness" look, where 5 = no change and 1 = severe 

change. 

Set forth in Figures 9, 10 and 11 below are the results of the Hexapod Wear Test conducted 

by Mohawk at its industry certified lab in Lyerly, Georgia on three carpet samples consisting 

of carpets of identical constructions9 made from nylon fiber, PET fiber, and PTT fiber. Tests 

were performed after 12K cycles, 24K cycles, and 36K cycles. These tests reveal that carpet 

made from PTT fibers perform better than carpet made from PET fibers. The performance of 

PTT is equal to the performance of nylon, which has been the performance standard for 

consumer carpet prior to the introduction of PTT. Such performance continues over time as 

demonstrated by this industry standard accelerated wear test. 

Figure 9: Hexapod Wear Test (12K Cycles) 

Carpet 

Hex. 12K 

Nylon PET

4.5

4.0

3.5

3.0

2.5

Individual Value Plot of Hex. 12K vs Carpet 

PTT 

There are statistically significant differences between PET, and both PTT and nylon. PTT’s 

performance continues to be like nylon, rather than PET polyester. The differences 

between PTT and nylon are not statistically significant. 

9

 See appendix for test carpet constructions 

14
Sorona

Sorona

Figure 10: Hexapod Wear Test (24K Cycles) 

Carpet 

Hex. 24K 

Nylon PET

4.5

4.0

3.5

3.0

2.5

2.0

1.5

Individual Value Plot of Hex. 24K vs Carpet 

PTT 

After 24K cycles, there continue to be statistically significant differences between PET, 

and both PTT and nylon. PTT’s performance continues to be like nylon. The differences 

between PTT and nylon are not statistically significant. 

Figure 11: Hexapod Wear Test (36K Cycles) 

Carpet 

Hex. 36K 

Nylon PET

4.0

3.5

3.0

2.5

2.0

1.5

1.0

Individual Value Plot of Hex. 36K vs Carpet 

PTT 

After 36K cycles, statistically significant differences continue between PET, and both PTT 

and nylon. PTT’s performance remains like nylon. The differences between PTT and 

nylon are not statistically significant. 

While hexapod test data simulates wear through a mechanical device, PTT’s advantages over 

PET are equally apparent when carpet is walked on by human subjects. The performance of 

nylon, PET, and PTT carpet in this test is compared by measuring the appearance of carpet 

after a certain numbers of cycles (human footsteps on carpet). Results of this test conducted 

at an industry certified testing lab operated by Mohawk at Lyerly, Georgia after 20 thousand, 

15
Sorona

40 thousand and 60 thousand cycles are set forth below in Figures 12, 13, and 14. Consistent 

with the results from the hexapod test, the performance of PTT carpet was much better than 

the performance of PET carpet and was comparable to the performance of nylon carpet. 

Figure 12: Performance Appearance Rating (20K Cycles) 

Carpet 

PA

R 20K 

Nylon PET

4.5

4.0

3.5

3.0

2.5

2.0

Individual Value Plot of PAR 20K vs Carpet 

PTT 

There are statistically significant differences between PET, and both PTT and nylon.

In other words, PTT’s performance in this test is like nylon, rather than polyester. The

differences between PTT and nylon are not statistically significant.

16
After 40K cycles, there are also statistically significant differences between PET, and both

Sorona and nylon. Again, Sorona s performance in this test is like nylon, rather than

polyester. The differences between Sorona and nylon are not statistically significant.

Sorona

Sorona

After 60K cycles, there are also statistically significant differences between PET, and both

Sorona and nylon. Sorona’s performance continues to be like nylon, rather than

polyester. The differences between Sorona and nylon are not statistically significant. 

Figure 13: Performance Appearance Rating (40K Cycles) 

’ 

Carpet 

PA

R 40K 

Nylon PET

4.0

3.5

3.0

2.5

2.0

1.5

Individual Value Plot of PAR 40K vs Carpet 

PTT 

After 40K cycles, there are also statistically significant differences between PET, and both PTT and nylon. Again, PTT’s performance in this test is like nylon, rather than polyester. The difference between PTT and nylon are not statistically significant. 

Figure 14: Performance Appearance Rating (60K Cycles) 

Carpet 

PAR 60K 

Nylon PET

4.0

3.5

3.0

2.5

2.0

1.5

Individual Value Plot of PAR 60K vs Carpet 

PTT 

After 60K cycles, there are also statistically significant differences between PET, and both nylon and PTT. PTT’s performance continues to be like nylon, rather than polyester. The 

differences between PTT and nylon are not statistically significant. 

The data in Figures 15(a) and 15(b) is provided as additional confirmation of the superior 

durability and resiliency of even low denier per filament (dpf), soft PTT fiber as compared to 

17
identical PET fiber. Shell Chemical LP, acting under contract as the marketing and technical 

service provider to PTT Canada, arranged to have identical PTT and PET carpets made and 

tested. The bulked continuous filament (BCF) yarns were made on a commercial extruder at 

CAF Extrusion, Inc. in Calhoun, Georgia. The same spinneret with 120 holes was used for 

both yarns resulting in 12 dpf PTT and PET yarns. These yarns were then each twisted at 5 

turns-per-inch (TPI), Superba heat-set, and converted into carpet. Durability and resiliency 

testing was conducted at the certified laboratory of Independent Textile Testing Service, Inc. 

(ITTS) in Dalton, Georgia. The carpet specifications are shown in Table 4 below; each point 

is the average of three ‘raters’. 

Table 4: Head-to-head comparison of PTT vs PET carpets 

Carpet Construction Details 25-ounce per square 35-ounce per square 

yard yard 

PTT PET PTT PET 

Gauge 5/32 5/32 3/16 3/16 

Pile Height (inches) 13/32 13/32 3/4 3/4 

Stitches per Inch (SPI) 10 10 10 10 

Wear Performance 

20 K Cycle Walk Test 3.5 2.7 3.9 3.0 

12 K Cycle Hexapod 3.4 1.8 4.0 3.2 

Figure 15(a) : Hexapod Wear Test – 25 Oz Per SqYd (opsy) carpet, 12K cycles 

18
Figure 15(b) : Hexapod Wear Test – 35-Oz Per SqYd (opsy) carpet, 12K cycles 

b) Softness 

Softness is an aesthetic that is valued particularly for apparel fabrics, where skin contact is 

prevalent. Softness in carpet, on the other hand, is not associated with direct skin contact. In 

both cases, softness is impacted by the ease in which yarns can bend. While fabric and carpet 

construction differences can vary widely, articles constructed similarly from different fibers 

or yarns have softness values that reflect the differences in their constituent polymers. A 

very useful measure of this difference in yarn softness is the force or stress required to deflect 

or strain the fiber a given distance. Therefore the stress vs. strain curves for fibers made from 

different polymers correlates well with expected fabric softness aesthetics. Figure 16 (as 

shown on the following two pages) represents first the stress vs. strain performance of PET 

and PTT fibers as compared to nylon 66 using 56 dtex yarns, and second a measure of relative 

softness by showing a comparison of the force to deflect these same yarns a given distance. 

19
Figure 16: Stress vs. Strain and Softness measurements (cn/dtex and gms force) of 

PET, N6,6 and PTT yarns (ref http://www.solotex.co.jp/en/soft.html)

PET 

Nylon 66 

PTT 

20
PTT PET Nylon 66

21
c) Stretch with recovery 

The superior stretch and recovery properties of fabrics knitted or woven from PTT compared 

to fabrics made with PET is demonstrated by the following tests conducted for PTT Canada 

by Shell Chemical: 

Knitted Fabrics 

Knitted fabrics with identical constructions made from draw-textured PET and PTT yarns 

were dyed and heat-set according to widely used industry protocols. 76/32 PET yarns were 

compared to 78/32 PTT yarns. The PTT was disperse dyed at atmospheric boil and finished at 

150°C while the PET fabric was dyed at 130°C and finished at 180°C. The two knitted 

fabrics were also softened with equal amount of silicone softener. 

Figure 17 (a) shows the % fabric elongation at 10 N force and Figure 17 (b) show the % 

permanent deformation after one cycle loading. Even though the PET fabric has slightly 

higher elongation characteristics (an artifact of the fabric construction as explained below) the 

PTT fabric has better recover and thus lower set than the PET fabric. 

Figure 17: (a) % Elongation performance for fabrics @ 10 N force; (b) % Permanent 

set for fabrics after elongation @ 10 N force (ref 6) 

130 

140 

150 

160 

170 

180 

190 

% Elongation 

0 

2 

4 

6 

8 

10 

% Permanent Set 

PTT PET PTT PET 

78/32 76/32 78/32 76/32 

Woven Fabrics 

The PET and PTT yarns used for comparing woven fabrics were 72/36 and 78/22 

respectively. The number of picks/cm used for the PTT fabric was 40 while only 31 

picks/cm were used for the PET fabric, which explains the slightly higher elongation. 

Both fabrics were woven with a 2/1 construction. Since commercial PET draw-textured 

yarns were used in the woven fabrics evaluation, there were some differences in the yarn 

counts, which must be taken into account when comparing the stretch and recovery of the 

fabrics. 

Figure 18 shows the % stretch of these fabrics in the weft direction with 10 N load, and 

the permanent set after one cycle loading. The PTT woven fabric has high stretch of 22.5 

compared to the 8% stretch of the PET fabric. Both fabrics have <5% permanent set after 

one cycle loading. 

22
Figure 18: % Elongation in the weft direction of PET and PTT woven fabrics (ref 6) 

40

30

20 

10 

0

PET PTT

Other Information Relevant To This Petition 

Subclass Definition 

Applicants propose the following definition for a new subclass of polyester at 16 C.F.R. 

303.7(c): 

"[a] manufactured fiber in which the fiber-forming substance is any long chain 

synthetic polymer composed of at least 85% by weight of an ester of a substituted 

aromatic carboxylic acid, including but not restricted to substituted terephthalate units, 

[formula omitted] and para substituted hydroxy-benzoate units, [formula omitted] and 

where specifically the glycol used to form the ester consists of at least ninety mole 

percent 1,3-propanediol." 

This definition is appropriate because if a polymer manufacturer uses the above proportions of 

starting materials, the resultant polymer will exhibit a molecular or crystalline structure that 

will permit fiber extruded from such polymer to exhibit the properties described in this 

petition. 

Extent of Commercialization of PTT Fibers 

PTT has been commercialized by E. I. du Pont de Nemours and Company and PTT Canada. 

Carpet fiber spun from PTT has been commercialized by Mohawk Industries (including Lees 

Carpets), Shaw Industries and CAF Extrusions. Apparel fibers spun from PTT have been 

commercialized by the following firms mills grouped according to apparel type: % Elongation 

23
PTT apparel fiber mills grouped by apparel type 

• Swimwear 

O-Sung, Houndey, Haitian 

• Active Sportswear 

Everest, Favis, Yon-Il K, FETL, Shanghai Challenge 

• Casual Shirts and Pants 

Akore, Huvis, Visionland, Chia Her, Wujiang Jili 

• Casual Shirts 

O-Sung, Samil 

• Jackets and Pants 

Saehan, Ulhwa 

• Ready to Wear 

New Wide, True Way, Haitian, Fountain Set 

• Luggage/Backpacks 

Rueyhwa, Tay Shin 

Suggested Names For A New Subclass of Polyester Fiber Than May Be Used With 

Respect To Fibers Spun From PTT 

As indicated above, Petitioners propose in order of preference: 

1. triexta; 2. resisoft; and 3. durares. 

as possible generic names for a new subclass of PTT fibers. 

Petitioners have done word searches for each of these proposed generic subclass names and 

have found no confusingly similar use of these names by any other company either as a 

trademark or product name. 

Petitioners note the Commission’s choice of “PTT001” as a temporary designation. 

Recycling Properties 

Recycling of man-made fibers, while of secondary importance for consumers in the United 

States at this time, will assume increasing importance as consumers increasingly adopt 

preferences for sustainable products. To the extent that PET and PTT are included in the 

same pool of polymer to be recycled because they are currently both classified as polyester, 

mixing of the two types of polyester could have adverse effects on the properties of the 

recycled polymer (melt temperature and tenacity) and will require different safe handling 

24
procedures during processing. For this reason, the use of a different generic that would 

facilitate the separation of the polymers during recyling is an important consideration. 

Figure 20: impact of mixing waste PET and PTT on melting temperature of the polymer 

(ref7) 

300

250

Melting Point, oC 

200

150

100

50

0

0 20 40 60 80 100

Mole % PTT 

Figure 21: tenacity of PET fibers melt blended with PTT(ref8) 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

Tena

city (cN/tex) 

0 20 40 60 80 100

% PTT 

25
Finally, the major byproduct produced during the processing of PET is acetaldehyde. The 

major byproduct produced during the processing of PTT is acrolein. These gases have 

different properties and quite different OSHA 8 hour personal exposure limits and short-term 

exposure limits. Since firms involved in recycling articles made from PET vs. PTT should be 

aware of these differences, a new generic name for PTT is appropriate. 

Questions regarding this petition may be addressed to: 

Carl G. Bartholomaus, Corporate Counsel 

DuPont Company 

Building 23-2128 

Barley Mill Plaza 

Wilmington, DE 19880-0023 

302-992-3207 

Carl.G.Bartholomaus@usa.dupont.com 

Respectfully submitted: 

Mohawk Industries, Inc. 

By _____________________________ 

PTT Poly Canada 

By _____________________________ 

E. I. du Pont de Nemours and Company 

By _____________________________ 

26
References 

1. I. J. Desborough, I. H. Hall, and J. Z. Neisser, The Structure of Poly(trimethylene 

terephthalate), Polymer, 20, 545 (1979) 

2. R. Jakeways, I. M. Ward, and M. A. Wildings, Crystal Deformation in Aromatic Polyesters, J. 

Polym. Sci., Phys. Ed., 12, 799 (1975) 

3. H.H. Chuah, Synthesis, Properties and Applications of Poly(Trimethylene Terephthalate) 

in Schiers, J. and Long, T.E. ed., Modern Polyesters: Chemistry and Technology of 

Polyesters and Copolyesters, Chapter 11, pp. 361-391, John Wiley, 2003. 

4. I. Goodman, “Encyclopedia of Polymer Science”, Vol. 11, New York: J. Wiley and Sons, 

1969 

5. I.M. Ward, M.A. Wilding and H. Brody, The Mechanical Properties and Structure of Poly 

(m-methylene Terephthalate) Fibers, J. Polym. Sci., Polym. Phys. Ed., 14, 263 (1976). 

6. M. Moerman and G. Hess, Corterra Polymers, Value Proposition in TextileApparel 

Applications, Technical Bulletin, SC-3014-00, Shell Chemical-Company, 2000. 

7. E. Punusamy and T. Balakrishnan, Macromol. Sci., Chem., A22(3), 373(1985). 

8. W. Opperman, P. Hirt and C. Fritz, Chem. Fibers Int., 49, 33 

27
 CARPETS USED FOR PERFORMANCE TESTS

wt. gauge denier dpf polymer ply twist tpi Stain Blocker 

oz/yd2 

35 3/16 1480 18 PTT 1 x 1 5.5 No 

45 3/16 1480 18 PTT 1 x 1 5.5 No 

55 3/16 1480 18 PTT 1 x 1 5.5 No 

50 1/8 1480 18 PTT 1 x 1 5.5 No 

40 1/8 1480 18 PTT 1 x 1 5.5 No 

60 1/8 1480 18 PTT 1 x 1 5.5 No 

32 3/16 1480 18 PTT 1 x 1 5.5 No 

42 3/16 1480 18 PTT 1 x 1 5.5 No 

52 3/16 1480 18 PTT 1 x 1 5.5 No 

42 3/16 1480 18 PTT 1 x 1 5.5 No 

32 3/16 1480 18 PTT 1 x 1 5.5 No 

52 3/16 1480 18 PTT 1 x 1 5.5 No 

32 3/16 1480 18 PTT 1 x 1 5.5 No 

35 3/16 995 12 Nylon 2 x 2 6.5 x 1 Yes 

40 3/16 995 12 Nylon 2 x 2 6.5 x 1 Yes 

50 3/16 995 12 Nylon 2 x 2 6.5 x 1 Yes 

35 3/16 995 12 Nylon 2 x 2 6.5 x 1 Yes 

52 3/16 995 12 Nylon 2 x 2 6.5 x 1 Yes 

38 3/16 995 12 Nylon 2 x 2 6.5 x 1 Yes 

35 3/16 995 12 Nylon 2 x 2 6.5 x 1 Yes 

38 3/16 995 12 Nylon 2 x 2 6.5 x 1 Yes 

35 3/16 995 12 Nylon 2 x 2 6.5 x 1 Yes 

55 1/10 1045 12 Nylon 1 x 1 6.5 Yes 

46 1/8 1045 12 Nylon 1 x 1 5.25 Yes 

35 1/8 1045 12 Nylon 1 x 1 5.5 Yes 

65 1/10 1045 12 Nylon 1 x 1 6.5 Yes 

46 5/32 1045 12 Nylon 1 x 1 6.5 Yes 

34 3/16 1460 15 PET 1 x 1 5.5 No 

40 3/16 1460 15 PET 1 x 1 5.5 No 

51 3/16 1460 15 PET 1 x 1 5.5 No 

51 3/16 1460 15 PET 1 x 1 5.5 No 

40 3/16 1460 15 PET 1 x 1 5.5 No 

32 3/16 1460 15 PET 1 x 1 5.5 No 

40 3/16 1459 15 PET 1 x 1 5.5 No 

52 1/8 3.0 cc 15 PET Staple 1 x 1 4.8 x 4.0 No 

42 1/8 3.0 cc 15 PET Staple 1 x 1 4.8 x 4.0 No 

35 3/16 3.15 cc 15 PET Staple 1 x 1 5.3 x 6.4 No 

58 5/32 3.0 cc 15 PET Staple 1 x 1 4.8 x 4.0 No 

Appendix A: Carpets used for performance tests 

28