Technical Guide For Kevlar® in Mechanical Rubber Goods PDF
Technical Guide For Kevlar® in Mechanical Rubber Goods PDF
Technical Guide For Kevlar® in Mechanical Rubber Goods PDF
POWER OF PERFORMANCE
TABLE OF CONTENTS
TABLE OF CONTENTS
Tables
1.
2.
3.
4.
5.
6.
Figures
1.
2.
3.
Initial Modulus of Industrial Filament Yarns and Steel Wire in Air at Elevated Temperatures .............. 3
4.
5.
6.
7.
8.
9.
10.
11.
12.
Effect of Twist on Properties of 1500 Denier (1670 dtex) KEVLAR Yarn ................................... 10
13.
14.
15.
16.
17.
18.
19.
20.
21.
Appendices
ii
A.
B.
C.
Introduction
24
KEVLAR
20
175
18
150
16
125
14
12
100
DACRON
Polyester T-68
10
Nylon
T-728
8
6
75
50
Steel
Wire
NOMEX
Aramid
25
2
0
0
0
Tenacity, cN/tex
200
22
Tenacity, gpd
10
15
20
Elongation, %
Figure 1.
UNIT
TYPE 956
K29
TYPE 956C
K129
TYPE 956E
K119
TYPE 965
K49
Yarn
Denier (Decitex)
denier (dtex)
1500 (1670)
1500 (1670)
1500 (1670)
1420 (1580)
Specific Gravity
1.44
1.44
1.44
1.44
Commercial Moisture
Regain (ASTM D 1909)
7.0
7.0
7.0
3.5
lb(N)
75.1 (334)
83.3 (371)
78.7 (350)
69.5 (309)
gpd (cN/tex)
22.7 (200)
25.2 (222)
23.8 (210)
22.2 (196)
3.35
3.15
4.11
2.49
gpd (cN/tex)
591 (5216)
750 (6620)
424 (3742)
856 (7555)
lb (N)
76.0 (338)
56.2 (250)
80.7 (359)
52.8 (235)
gpd (cN/tex)
11.5 (102)
12.7 (112)
12.1 (107)
10.5 (93)
2.2
1.7
2.7
1.3
Stress-Strain Properties*
Straight Test on Yarns
Breaking Strength
Breaking Tenacity
Elongation at Break
Initial Modulus
Loop Test on Yarns
Breaking Strength
Breaking Tenacity
Elongation at Break
*ASTM D 885-85 (tested at 1.1 Twist Multiplier)
PROPERTY
Shrinkage
In water at 212F (100C)
In Dry Air at 351F (177C)
%
%
<0.1
<0.1
Shrinkage Tension
In Dry Air at
351F (177C)
gpd
cN/tex
<0.1
<0.88
Specific Heat
At 77F (25C)
At 212F (100C)
At 356F (180C)
J/(kg.C)
1420
2010
2515
Btu/lb.F
0.34
0.48
0.60
Thermal Conductivity
Btuin/(hft2F)
W/(mK)
0.3
0.04
in/(inF)
cm/(cmC)
2.2 x 106
4.0 x 106
F
C
800900
427482
*Tested with zero twist yarn at 0.2 gpd (1.8 cN/tex) tension
**Varies with rate of heating
200
175
150
16
125
12
100
Nylon
75
DACRON
Polyester
Tenacity, cN/tex
Tenacity, gpd
20
50
25
Steel Wire
0
0
0
100
38
200
93
300
149
400
204
0
500F
260C
Test Temperature
100
80
80
KEVLAR
60
60
40
DACRON
Polyester
20
0
300
400
0
500
60
KEVLAR
600
500
40
400
30
300
Steel Wire
200
DACRON Polyester
100
Nylon
0
0
0
100
38
200
300
93
149
Test Temperature
20
Modulus, N/tex
50
Modulus, gpd
200
Figure 4.
Figure 3.
100
700
20
Nylon
0
Figure 2.
40
KEVLAR
24
10
0
400F
204C
75F(24C)
50F(46C)
Straight Properties
Tenacity
gpd
cN/tex
19.1
169
19.8
175
Modulus
gpd
cN/tex
425
3,753
478
4,221
Break Elongation, %
4.1
3.9
Loop Properties
Tenacity
gpd
cN/tex
8.3
73.3
7.7
68.0
Break Elongation, %
2.0
1.8
Note: A 30-inch sample cord twisted to 6.5 twist multiplier was tested, of
which 18 inches were exposed to the cold chamber at a 10%/minute
strain rate.
24
320F
(160C)
20
150
125
12
392F
(200C)
100
Tenacity, cN/tex
Tenacity, gpd
16
75
% CREEP
0.5
0.5
0.7
2.1
4.8
4.9
<0.03
<0.03
<0.03
0.3
0.4
1.4
KEVLAR
Glass
Wire
DACRON Polyester
Nylon
Rayon
175
356F
(180C)
% GROWTH
482F
(250C)
50
4
25
Test Conditions:
1 gpd (8.83 cN/tex) load at 75F (24C).
Growth measured at 30 seconds.
Creep is the length change between 30 seconds and 30 minutes.
Figure 5.
100
200
300
400
Exposure Time, hours
500
Creep
By definition, creep is the slow, continued growth or
lengthening of a material under constant load. With organic
fibers, this lengthening process is sometimes split into two
regions. The first, somewhat abrupt change is called growth,
and refers to the length change between 0 and 30 seconds.
The second, much more gradual change is called creep, and
lasts from 30 seconds until the end of 30 minutes. The entire
30-minute process is often referred to as creep-growth.
Table 4 compares growth and creep values of KEVLAR
with those of glass, wire, polyester, nylon, and rayon.
Stress Rupture
Stress rupture is the sudden failure of a material when it
is held under a load less than its tensile strength. For
practical purposes, stress rupture is measured under a
constant load that causes the failure to take place over
relatively long periods of time. The greater the load, the
more quickly failure occurs. However, even the smallest
load could theoretically cause stress rupture if enough
time were allowed.
Moisture Regain
Moisture regain is the tendency of most organic fibers to
pick up or give off ambient atmospheric moisture until
they reach an equilibrium moisture content at a controlled
relative humidity and temperature. It is defined as the
percentage of moisture in an item brought into equilibrium
with a standard atmosphere after partial drying, calculated
as a percentage of the moisture-free weight (see Appendix
A). The amount of moisture regain is important because
the properties of most organic fibers are influenced by
the fibers moisture content. In this respect, KEVLAR
16
Log Time to Break, seconds
KEVLAR
12
Nylon
100 yr
8
1 yr
Polyethylene
0
0
Figure 6.
20
40
60
80
Load, % of Ultimate Tensile Strength
100
Moisture Regain, %
10
8
4
Bone-dried at 221F (105C) for 4 hours
prior to exposure to 65% RH
2
0
0
Figure 7.
20
40
60
80
100
120
Time, hours at 65% RH and 72F (22C)
140
0
20
40
60
80
Generally:
RETAINED STRENGTH, %
100
96
91
88
84
Chemical
Concentration,
%
Temp.,
F (C)
Time,
hrs
Acids
Acetic
Acetic
Benzoic
Chromic
Formic
Formic
Formic
Hydrobromic
Hydrochloric
Hydrofluoric
Nitric
Nitric
Oxalic
Phosphoric
Phosphoric
Phosphoric
Salicylic
Sulfuric
Sulfuric
Sulfuric
40
40
3
10
90
40
90
10
10
10
1
10
10
10
10
10
3
10
70
10
70 (21)
210 (99)
210 (99)
70 (21)
70 (21)
70 (21)
210 (99)
70 (21)
160 (71)
70 (21)
70 (21)
70 (21)
210 (99)
70 (21)
70 (21)
210 (99)
210 (99)
70 (21)
70 (21)
210 (99)
1000
100
100
1000
100
1000
100
1000
10
100
100
100
100
100
1000
100
1000
100
100
10
28
40
10
70 (21)
70 (21)
210 (99)
1000
100
100
X
X
100
100
100
100
100
100
50/50
100
100
100
Boil
70 (21)
70 (21)
Boil
70 (21)
170 (77)
210 (99)
70 (21)
70 (21)
70 (21)
100
1000
1000
100
1000
100
1000
1000
1000
1000
X
X
X
3
3
3
3
10
10
5
70 (21)
210 (99)
210 (99)
70 (21)
210 (99)
250 (121)
210 (99)
1000
100
100
1000
100
100
100
100
100
100
10
100
100
100
5
100
100
70 (21)
235 (113)
70 (21)
70 (21)
70 (21)
70 (21)
210 (99)
70 (21)
250 (121)
210 (99)
1000
100
1000
1000
1000
1000
10
10
10
100
None
Degraded
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Bases
Ammonium Hydroxide
Sodium Hydroxide
Sodium Hydroxide
Organic Solvents
Acetone
Amyl Alcohol
Benzene
Carbon Tetrachloride
Ethyl Ether
Ethyl Alcohol
Ethylene Glycol/Water
SUVA Centri-LP (HCFC-123)
Gasoline, Leaded
Methyl Alcohol
X
X
X
X
X
X
X
Salt Solutions
Copper Sulfate
Copper Sulfate
Ferric Chloride
Sodium Chloride
Sodium Chloride
Sodium Chloride
Sodium Phosphate
X
X
X
X
X
X
Miscellaneous Chemicals
Benzaldehyde
Brake Fluid
Cottonseed Oil
Formaldehyde in Water
Lard
Linseed Oil
Mineral Oil
Phenol in Water
Resorcinol
Water, Tap
X
X
X
X
X
X
X
X
X
* None 0 to 10% strength loss; Slight 11 to 20% strength loss; Moderate 21 to 40% strength loss; Appreciable 41 to 80% strength loss; Degraded 81 to 100% strength loss.
Hybrid Cords
Figure 8.
26
18
21
16
16
14
11
6
1
0
4
6
8
Parts per Hundred Rubber
10
12
Tenacity, gpd
20
175
1500/1/2 KEVLAR
150
Hybrid A
12
125
Hybrid B
1100/4 1260/1/2
Polyester Nylon
10
75
8
6
100
Tenacity, cN/tex
50
4
25
2
0
0
0
Figure 9.
8
12
16
Elongation %
20
24
Introduction
Twisting Guidelines
KEVLAR yarns can be twisted successfully on standard
textile equipment, provided the following recommendations
are followed to ensure high-quality processing:
Allow the yarn to condition for 24 to 48 hours before
processing. As with other fibers, the preferred processing
conditions for KEVLAR are 7280F (2227C) and
60 to 68% relative humidity. Low relative humidity tends
to dry out the yarn and increase the frictional forces. As
static charges build up, the filaments separate and are
susceptible to damage when contacting yarn guides.
Rotating
Thread
Guides
Ply Spools
Pigtail
Thread
Guides
Supply
Rubber
Covered
Nip Roll
Thread Guides
(Pigtails)
Tension
Device
Stop
Motion
Detector
Delivery
Rolls
Volumetric
Thread
Guide
Feed
Rolls
Lappet
Guide
Lappet
Guide
Balloon
Control
Balloon
Control
Ring
Traveller
Traveller
Ring
Ring
Spindle
Spindle
Guides
Chrome oxide, matte finished chrome or ceramic guide
surfaces which are clean and nick-free are preferred.
Average surface roughness of 1540 microinches
(0.41.0 micrometers) and a coefficient of friction not
exceeding 0.25 are preferred. Polished chrome, steel,
brass, porcelain, and glass are not recommended.
24
22
Tenacity
600
20
18
14
400
12
300
10
Elongation
4
200
3
Tensioners
Yarn tensions must be uniform and equal on all ends
(0.05 grams per denier [0.44 cN/tex] or more suggested,
but 0.01 grams per denier [0.09 cN/tex] is satisfactory).
1
0
0
0
1
2
3
Twist Multiplier (TM)
22
190
180
20
160
18
Water-Dipped
150
16
140
130
14
Tenacity, cN/tex
170
Greige
Tenacity, gpd
100
5
Break Elongation, %
Tenacity, gpd
16
Modulus, gpd
500
Modulus
700
120
110
12
3
5
6
7
Twist Multiplier (TM)
700
60
400
30
300
Greige
200
20
100
10
180
800
750
170
346 x 346 tpm
160
5
6
7
Twist Multiplier (TM)
700
240
6.1
7
Greige
6
5
4
Water-Dipped
3
2
4
5
6
7
Twist Multiplier (TM)
280
7.1
320
360
8.1
9.1
Yarn Twist
400
10.2
tpm
tpi
Elongation, %
850
190
Break Strength, lb
Modulus, gpd
40
Modulus, cN/tex
Water-Dipped
500
900
200
50
Break Strength, N
600
Fatigue Resistance
In a discussion of fatigue resistance, expecially for highmodulus fibers, fatigue should be separated into three
categories:
Flex fatigue is the result of compression or compression
and abrasion which occurs when a specimen is
repeatedly subjected to flexing or bending over a
given radius.
Abrasion fatigue occurs when the filaments of yarn
rub against each other or against a contact surface.
Tension-tension fatigue takes place when the internal
molecular/crystalline structure is subjected to a pullpull type fatiguing motion.
100
8.5 TM
80
6.5 TM
60
5.0 TM
40
4.0 TM
20
0
0
10
12
14
Compression, %
11
100
8% Compression
80
15% Compression
60
40
18% Compression
20
0
4
6
7
Twist Multiplier (TM)
20
40
60
80
100
0
0
5.0 TM
6.5 TM
Twist Multiplier (TM)
8.5 TM
Adhesion Systems
Excellent adhesion of KEVLAR to most compounds
can be obtained with a two-dip system based on an epoxy
or polyaryl-polyisocyanate subcoat and a resorcinolformaldehyde-latex topcoat. For applications requiring a
stiffer reinforcement (e.g., V-belts), polyaryl-polyisocyanate subcoat in a solvent carrier is recommended.
Appendix B shows a typical adhesive system (dip formulations and treating conditions) for KEVLAR used in
mechanical rubber goods. Please consult your Technical
Marketing Representative for adhesive system optimization.
Dip Hot-Stretching
Dip hot-stretching refers to the combined operation of
applying a liquid adhesive dip to the item, then drying
and heating (during) the dip and stretching the item in a
series of ovens. The treating conditions required to prepare
the cords or fabrics of KEVLAR differ markedly
because of differences in cord and fabric constructions,
differences in chemistry and complexity of the adhesive
system, and differences in the hot-stretching equipment.
Although typical treating conditions are listed in
Appendix B, your Technical Marketing Representative
should be consulted to optimize treating conditions for
your specific application.
Dipping is achieved by passing the item through a
trough or tank containing a dip which is typically an
aqueous dispersion or solution. If a solvent-based dip is
used, precautions must be taken to avoid contaminating
the atmosphere with the solvent vapor and, in case of
flammable solvents, steps must be taken to avoid ignition
sources. The preferred method of multiple dipping is to
perform these operations in a continuous sequence,
without any interruption. Before a second dip can be
applied, the first one must be thoroughly dried.
Ovens
k
b
e
Subcoat
Topcoat
Greige fabric,
yarn or cord
Dipped fabric,
yarn or cord
13
Density
1 g/cc = 103 kg/m3 = 62.43 lb/ft3 = 0.03613 lb/in3
Length
1 m = 39.37 inches
1 inch = 25.4 mm
Mass
1 lb = 0.4536 kg
1 kg = 2.205 lbs
Temperature
C = (F 32)/1.8
KEVLAR
Steel
Nylon
F = (C x 1.8) + 32
Twist
1 turn/meter (tpm) = 0.0254 turns/inch (tpi)
1 turn/inch (tpi) = 39.37 turns/meter (tpm)
Rayon
High-strength polyethylene
S-glass
E-glass
Twist Multiplier
Viscosity
1 centipoise = 10-3 Pas (pascal second)
1 centistokes = 10-6 m2/s
Note: For a more complete list of conversion factors, please consult ASTM
E 380-91a titled Standard Practice for Use of the International
System of Units (SI) (the Modernized Metric System).
Moisture
Moisture Content (%) =
100
100
15
Treating Conditions
Oven Conditions
Oven 1
Oven 2
Dip Applied
Subcoat
Topcoat
Phase
470 (243)
450 (232)
60
60
1.0 (8.8)
0.3 (2.6)
9.317
0.403
1.453
11.173
II
16.123
III
0.726
3.396
4.122
IV
0.788
3.984
Parts by Weight
9.685
0.037
0.056
TOTAL
0.222
TOTAL
10.000
Mixing Procedure
1. Mix the portions of water, 10% sodium carbonate,
and 5% Aerosol OT together until thoroughly
blended.
Ingredients
Parts by Weight
36.190
6. Age the mixture for 12 hours at 70 to 72F (temperature is critical and must be controlled during aging).
This mixture is the base dip and can be stored in a temperature controlled tank at 52 to 58F for up to 5 days.
7. The final dip is made by adding and mixing the
required amounts of the wax and carbon black
dispersions (Phase IV and Phase V), in that order, to
the base dip. The dip must be made up fresh every 8
hours for continuous dipping operations.
Note: The above topcoat formulation and mixing procedures should result
in adequate yarn-to-elastomer adhesion (when coupled with the
subcoat at the recommended treating conditions) in most mechanical
rubber goods applications. To optimize adhesion for your specific
application, please consult your Technical Marketing Representative.
16
APPENDIX
Bulletins
Technical Guide for KEVLAR Brand Fiber
KEVLAR Fiber Products Material Safety Data Sheet
Technical Guide for NOMEX Brand Fiber
Source Lists
Suppliers of Yarn Guides and Tensioners
Manufacturers of Tools for Cutting Yarns or Fabrics Containing KEVLAR
Converters of KEVLAR Brand Yarn
Manufacturers of Hoses Reinforced with KEVLAR Brand Fiber
Manufacturers of Power Transmission Belts Reinforced with KEVLAR Aramid
Manufacturers of Conveyor Belts Reinforced with KEVLAR Aramid
Manufacturers of Thermoplastic Hoses Reinforced with KEVLARAramid
Suppliers of Twisted and Treated Yarns/Cords of KEVLAR and NOMEX Aramid
Commercial Weavers of Fabrics of KEVLAR Brand Fiber
Coaters and Laminators for Fabrics of KEVLAR Brand Fiber
Note:
The products presented in this bulletin are commercial products. Other products
of KEVLAR, with end-use tailored properties, are continuously being
developed by DuPont. Please contact your DuPont Sales Representative or call
one of our Applications Specialists at 1-800-453-8527 for more information.
17
Canada:
DuPont Canada Inc.
Advanced Fibers Systems
P.O. Box 2200
Streetsville Postal Station
Mississauga, Ontario L5M 2H3
Tel: (800) 387-2122
(905) 821-5193
Fax: (905) 821-5177
E-Mail: products@can.dupont.com
Europe:
DuPont KEVLAR
P.O. Box 50
CH-1218 Le Grand-Saconnex
Geneva, Switzerland
Tel. ++ 41-22-717 51 11
Fax: ++ 41-22-717 60 21
Japan:
DuPont Toray Company, Inc.
1-5-6 Nihonbashi-Honcho,
Chuo-ku, Tokyo 103
Japan
Tel: 81-3-3245-5080
Fax: 81-3-3242-3183
Australia:
DuPont Australia Ltd.
254 Canterbury Road
Bayswater, Victoria 3153
Australia
Tel: 61-3-9721 5900
Fax: 61-3-9721 5636
This information represents our current knowledge on the subject. It is offered solely to provide possible suggestions for your own experimentation. It is not
intended, however, to substitute for any testing you may need to conduct to determine for yourself the suitability of our products for your particular purposes.
This information is subject to revision as new knowledge and experience becomes available. Since we cannot anticipate all variations in actual end-use
conditions, DuPont makes no warranties and assumes no liability in connection with any use of this information. Nothing in this publication is to be
considered as a license to operate under or a recommendation to infringe any patent right.
KEVLAR, NOMEX, DACRON, and SUVA are registered trademarks of E. I. du Pont de Nemours and Company.
KEVLAR
POWER OF PERFORMANCE