This chapter covers a series of plastics of which the imide group is an important part of the molecule. The imide group is formed by a condensation reaction of an aromatic anhydride group with an aromatic amine as shown in Figure 7.1.
Figure 7.1
Reaction of amine with anhydride to form an imide.
This group is very thermally stable. Aliphatic imides are possible, but the thermal stability is reduced, and thermal stability is one of the main reasons to use an imide type polymer.
7.1.1. Polyetherimide
Polyetherimide (PEI) is an amorphous engineering thermoplastic. Thermoplastic PEIs provide the strength, heat resistance, and flame retardancy of traditional polyimides (PIs) with the ease of simple melt processing seen in standard injection-molding resins like polycarbonate and ABS.
The key performance features of PEI resins include:
• excellent dimensional stability at high temperatures under load
• smooth as-molded surfaces
• transparency, though slightly yellow
• good optical properties
• very high strength and modulus
• high continuous-use temperature
• inherent ignition resistance without the use of additives
• good electrical properties with low ion content
There are several different polymers that are offered in various PEI plastics. The structures of these are shown in Figure 7.2, Figure 7.3, Figure 7.4, Figure 7.5 and Figure 7.6 with references to one of the product lines that utilize that molecule.
Figure 7.2
Chemical structure of BPADA–PPD PEI (Ultem® 5000 Series).
Figure 7.3
Chemical structure of biphenol diamine PMDA PEI (Aurum®, Vespel® TP-8000 Series).
Figure 7.4
Chemical structure of BPADA–DDS PEI sulfone (Ultem® XH6050).
Figure 7.5
Chemical structure of BPADA–MPD PEI (Ultem® 1000 Series).
Figure 7.6
Chemical structure of BPADA–PMDA–MPD copolyetherimide (Ultem® 6000 Series).
The acid dianhydride used to make most of the PEIs is 4,4′-bisphenol A dianhydride (BPADA), the structure of which is shown in Figure 7.7.
Figure 7.7
Chemical structure of BPADA monomer.
Some of the other monomers used in these PEIs are shown in Figure 7.8.
Figure 7.8
Chemical structures of other monomers used to make PIs.
Many products are called thermoplastic polyimide (TPI) by their manufacturer. These can usually be classified as PEIs.
7.1.2. Polyamide-Imide
Polyamide-imides (PAIs) are thermoplastic amorphous polymers that have useful properties:
• Exceptional chemical resistance
• Outstanding mechanical strength
• Excellent thermal stability
• Performs from cryogenic up to 260°C
• Excellent electrical properties
The monomers used to make PAI resin are shown in Figure 7.9.
Figure 7.9
Chemical structures of monomer used to make PAIs.
When these monomers are reacted carbon dioxide, rather than water, is generated. The closer the monomer ratio is to 1:1 the higher the molecular weight of the polymer shown in Figure 7.10.
Figure 7.10
Chemical structure of a typical PAI.
7.1.3. Polyimide
PIs are high-temperature engineering polymers originally developed by the DuPont Company. PIs exhibit an exceptional combination of thermal stability (>500°C), mechanical toughness, and chemical resistance. They have excellent dielectric properties and inherently low coefficient of thermal expansion. They are formed from diamines and dianhydrides such as those shown in Figure 7.11.
Figure 7.11
Chemical structures of monomer used to make PIs.
Many other diamines and several other dianhydrides may be chosen to tailor the final properties of a polymer whose structure is like that shown in Figure 7.12.
Figure 7.12
Chemical structure of a typical PI.
7.1.4. Imide Polymer Blends
PI-based resins, especially PEI and PAI polymers, may also be combined with other polymers. The PEI resins have produced a surprising number of miscible (one-phase) and compatible blends. Compatible blends are phase-separated mixtures having sufficient attraction between phases to provide some level of molecular adhesion, resulting in stable morphology and giving rise to good mechanical properties.
PEI forms miscible blends with polyesters such as PBT and PET. These blends have a single glass transition temperature between that of the PEI and polyester. However, few of these are commercial products yet.
Blends of BPADA-based PIs are also miscible with polyaryl ether ketones such as polyetheretherketone (PEEK). As injection molded, many PEEK–PEI blends are transparent.
7.2. Polyetherimides
7.2.1. Fatigue Data
Figure 7.13.
Tensile stress amplitude vs. cycles to failure of SABIC Innovative Plastics Ultem® 1000—transparent, standard flow, unreinforced general-purpose PEI.
Figure 7.14.
Tensile stress amplitude vs. cycles to failure at 23°C of SABIC Innovative Plastics Ultem® 1010—transparent, enhanced flow, unreinforced general-purpose PEI.
Figure 7.15.
Tensile stress amplitude vs. cycles to failure at 23°C of SABIC Innovative Plastics Ultem® 2100—10% glass fiber reinforced, standard flow PEI.
Figure 7.16.
Tensile stress amplitude vs. cycles to failure at 23°C of two SABIC Innovative Plastics Ultem®—20% glass reinforced PEI plastics.
Figure 7.17.
Tensile stress amplitude vs. cycles to failure of SABIC Innovative Plastics Ultem® 2300—30% glass fiber reinforced, standard flow PEI.
Figure 7.18.
Tensile stress amplitude vs. cycles to failure at 23°C of two SABIC Innovative Plastics Ultem®—30% glass reinforced PEI plastics.
Figure 7.19.
Tensile stress amplitude vs. cycles to failure of SABIC Innovative Plastics Ultem® 2400—40% glass fiber reinforced, standard flow PEI.
Figure 7.20.
Tensile stress amplitude vs. cycles to failure of SABIC Innovative Plastics Ultem® 3452—45% glass/mineral reinforced, enhanced flow PEI.
Figure 7.21.
Tensile stress amplitude vs. cycles to failure of two SABIC Innovative Plastics Ultem® 4000 series PEI plastics.
Figure 7.22.
Tensile stress amplitude vs. cycles to failure of two SABIC Innovative Plastics Ultem® 9000 series PEI plastics.
Figure 7.23.
Tensile stress amplitude vs. cycles to failure of two SABIC Innovative Plastics Ultem® AR9000 series PEI plastics.
Figure 7.24.
Tensile stress amplitude vs. cycles to failure of three SABIC Innovative Plastics Ultem® CRS5000 series PEI plastics.
Figure 7.25.
Tensile stress amplitude vs. cycles to failure of two SABIC Innovative Plastics Ultem® series PEI plastics.
Figure 7.26.
Tensile stress amplitude vs. cycles to failure of three SABIC Innovative Plastics PEI plastics.
Figure 7.27.
Flexural stress amplitude vs. cycles to failure of three DuPont Engineering Polymers Vespel® TP-8000 Series—semicrystalline PEI plastics.
7.2.2. Tribology Data
Table 7.1. Tribological Properties of RTP Company RTP 4205 TFE 15 (TPI with 30% Glass Fiber Reinforcement and 15% PTFE) vs. 1018 C Steel (Data Obtained per ASTM 3702)
PV (KPa m/s)
Load (N)
Speed (m/s)
Wear Factor × 10−8 (mm3/Nm)
Dynamic Coefficient of Friction
70
1.80
0.25
160
0.54
70
0.90
0.50
310
0.62
70
0.45
1.00
224
0.68
175
4.50
0.25
64
0.64
175
2.25
0.50
58
0.66
175
1.15
1.00
194
0.62
350
9.00
0.25
212
0.52
350
4.50
0.50
270
0.57
350
2.25
1.00
402
0.41
Table 7.2. Tribological Properties of RTP Company RTP 4285 TFE 15 (TPI with 30% Carbon Fiber Reinforcement and 15% PTFE) vs. 1018 C Steel (Data Obtained per ASTM 3702)
PV (KPa m/s)
Load (N)
Speed (m/s)
Wear Factor × 10−8 (mm3/Nm)
Dynamic Coefficient of Friction
70
1.80
0.25
66
0.31
70
0.90
0.50
66
0.28
70
0.45
1.00
92
0.20
175
4.50
0.25
130
0.31
175
2.25
0.50
78
0.31
175
1.15
1.00
92
0.30
350
9.00
0.25
68
0.55
350
4.50
0.50
164
0.77
350
2.25
1.00
96
0.92
Table 7.3. Tribological Properties of RTP Company RTP 4299 × 71927 (TPI with Proprietary Composition) vs. 1018 C Steel (Data Obtained per ASTM 3702)
PV (KPa m/s)
Load (N)
Speed (m/s)
Wear Factor × 10−8 (mm3/Nm)
Dynamic Coefficient of Friction
70
1.80
0.25
50
0.28
70
0.90
0.50
48
0.28
70
0.45
1.00
62
0.28
175
4.50
0.25
290
0.16
175
2.25
0.50
444
0.17
175
1.15
1.00
348
0.17
350
9.00
0.25
130
0.19
350
4.50
0.50
164
0.19
350
2.25
1.00
278
0.20
Table 7.4. Tribological Properties of RTP Company RTP 4299 × 64425 (TPI with Proprietary Composition) vs. 1018 C Steel (Data Obtained per ASTM 3702)
PV (KPa m/s)
Load (N)
Speed (m/s)
Wear Factor × 10−8 (mm3/Nm)
Dynamic Coefficient of Friction
70
1.80
0.25
34
0.24
70
0.90
0.50
20
0.29
70
0.45
1.00
50
0.27
175
4.50
0.25
68
0.53
175
2.25
0.50
22
0.59
175
1.15
1.00
34
0.58
350
9.00
0.25
66
0.48
350
4.50
0.50
84
0.57
350
2.25
1.00
94
0.58
Table 7.5. Tribological Properties of RTP Company RTP 2100 AR 15 TFE 15 (15% Aramid Fiber Reinforced and 15% PTFE) vs. 1018 C Steel (Data Obtained per ASTM 3702)
PV (KPa m/s)
Load (N)
Speed (m/s)
Wear Factor × 10−8 (mm3/Nm)
Dynamic Coefficient of Friction
70
1.80
0.25
18
0.19
70
0.45
1.00
10
0.21
175
2.25
0.50
64
0.23
350
9.00
0.25
50
0.25
350
2.25
1.00
45
0.33
Table 7.6. Tribological Properties of Several SABIC Innovative Plastics Ultem® Series PEI Plastics
Material and Test
Value
Units
Test Method
Ultem® 1000
Taber Abrasion, CS-17, 1kg
10
mg/1000 cycle
ASTM D 1044
Ultem® 1010
Taber Abrasion, CS-17, 1kg
10
mg/1000 cycle
ASTM D 1044
Ultem® 4000
Taber Abrasion, CS-17, 1kg
33
mg/1000 cycle
ASTM D 1044
PV Limit, 0.51m/s
2.1
MPam/s
SABIC Method
K-factor × E–10, PV = 2000psifpm vs. steel
62
–
SABIC Method
K-factor × E–10, PV = 2000psifpm vs. self
1900
–
SABIC Method
Coefficient of friction on steel, static
0.25
–
ASTM D 1894
Coefficient of friction on steel, kinetic
0.24
–
ASTM D 1894
Ultem® 4001
Taber Abrasion, CS-17, 1kg
2
mg/1000 cycle
ASTM D 1044
PV Limit, 0.51m/s
1.9
MPam/s
SABIC Method
K-factor × E–10, PV = 2000psifpm vs. steel
72
–
SABIC Method
K-factor × E–10, PV = 2000psifpm vs. self
27
–
SABIC Method
Coefficient of friction on steel, kinetic
0.25
–
ASTM D 1894
Ultem® CRS5001
Taber Abrasion, CS-17, 1kg
10
mg/1000 cycle
ASTM D 1044
Table 7.7. Tribological Properties of Several DuPont Engineering Plastics Vespel® TP Series TPI Plastics
Grade
PV (MPam/s)
Coefficient of Friction
Wear Factor, K (10−10cm3/kgfm)
Resin Wear (mg)
Metal Wear (mg)
TP-8130—30% carbon fiber filled
2.5
0.05
66
10
<1
TP-8130—30% carbon fiber filled
3.3
0.04
77
16
<1
TP-8549—30% carbon fiber filled, improved wear and chemical resistant
2.5
0.05
49
9
<1
TP-8549—30% carbon fiber filled, improved wear and chemical resistant
3.3
0.05
63
14
<1
TP-8311—10% carbon fiber filled
0.5
0.10
670
23
<1
TP-8311—10% carbon fiber filled
1.0
0.10
490
34
<1
Suzuki thrust wear test results—dry.
Table 7.8. Tribological Properties of Several DuPont Engineering Plastics Vespel® TP Series TPI Plastics
Grade
PV (MPam/s)
Coefficient of Friction
Wear Factor, K (10−10cm3/kgfm)
Resin Wear (mg)
Metal Wear (mg)
TP-8130—30% carbon fiber filled
10.4
0.03
4
2
<1
TP-8130—30% carbon fiber filled
12.5
0.03
3
1
<1
TP-8549—30% carbon fiber filled, improved wear and chemical resistant
10.4
0.02
3
1
<1
TP-8549—30% carbon fiber filled, improved wear and chemical resistant
12.5
0.02
4
2
<1
TP-8311—10% carbon fiber filled
10.4
0.02
3
1
<1
TP-8311—10% carbon fiber filled
12.5
0.02
2
1
<1
Suzuki thrust wear test results—lubricated.
7.3. Polyamide-Imides
7.3.1. Fatigue Data
Figure 7.28.
Tension/tension stress amplitude vs. cycles to failure at 30Hz of two Solvay Torlon® PAI plastics.
Figure 7.29.
Tension/tension stress amplitude vs. cycles to failure at 2Hz of Solvay Torlon® 7130—30% carbon fiber, 1% PTFE PAI.
Figure 7.30.
Flexural stress amplitude vs. cycles to failure at 30Hz of several Solvay Torlon® PAI plastics.
Figure 7.31.
Flexural stress amplitude vs. cycles to failure at 30Hz and 177°C of several Solvay Torlon® PAI plastics.
7.3.2. Tribology Data
Figure 7.32.
Wear resistance vs. pressure at high velocity (4.06m/s) of several Solvay Torlon® PAI plastics.
Figure 7.33.
Wear resistance vs. pressure at low velocity (0.25m/s) of several Solvay Torlon® PAI plastics.
Figure 7.34.
Wear resistance vs. pressure at moderate velocity (1.02m/s) of several Solvay Torlon® PAI plastics.
Figure 7.35.
Wear factor vs. extended cure time at 260°C of Solvay Torlon® 4301—12% Graphite, 3% PTFE PAI.
Table 7.9. Wear Factor and Wear Rates of Several Solvay Torlon® PAI Plastics
Pressure (MPa)
PV
Wear Factor (10−10mms/mPah)
Wear Rate (10−6m/h)
4301
4275
4435
4301
4275
4435
Velocity—0.25m/s
1.379
0.350
8
6
0.3
0.2
3.447
0.876
30
36
2.7
3.1
6.895
1.751
59
40
20
10.4
7.0
3.4
10.342
2.627
20
15
5.3
3.8
13.790
3.503
17
15
6.1
5.1
Velocity—1.02m/s
0.345
0.350
12
13
0.4
0.5
0.862
0.876
60
28
71
5.3
2.5
6.2
1.724
1.751
113
54
24
19.8
9.4
4.2
2.586
2.627
126
15
33.1
4.0
3.447
3.503
Melted
15
Melted
5.1
Velocity—4.06m/s
0.086
0.350
69
9
2.4
0.3
0.215
0.876
102
50
8.9
4.4
0.431
1.751
135
86
67
23.6
15.0
11.7
0.646
2.627
155
56
40.8
14.7
0.862
3.503
Melted
38
Melted
13.2
Torlon® 4301—12% graphite, 3% PTFE.
Torlon® 4275—20% graphite, 3% PTFE.
Torlon® 4435—graphite, PTFE, and other additives.
7.4. Polyimides
7.4.1. Fatigue Data
Figure 7.36.
Fatigue resistance vs. temperature to failure at 30Hz and various cycles of machined DuPont Engineering Polymers Vespel® SP PI plastics.
7.4.2. Tribology Data
Figure 7.37.
Lubricated friction test: dynamic coefficient of friction vs. ZN/P by thrust bearing test against steel with Sunvis 31 Oil lubricant of DuPont Engineering Polymers Vespel® SP21—15% graphite filled PI.
Figure 7.38.
Lubricated friction test: wear factor vs. ZN/P by thrust bearing test against steel with Sunvis 31 Oil lubricant of DuPont Engineering Polymers Vespel® SP21—15% graphite filled PI.
Figure 7.39.
Lubricated starvation test: dynamic coefficient of friction vs. time in hours by thrust bearing test against steel with Sunvis 31 Oil lubricant of DuPont Engineering Polymers Vespel® SP21—15% graphite filled PI (redo this chart X-axis).
Figure 7.40.
Dynamic coefficient of friction vs. temperature by thrust bearing test against unlubricated steel of two DuPont Engineering Polymers Vespel® SP PI plastics.
Figure 7.41.
Pressure vs. velocity limit at 395°C against unlubricated carbon steel of DuPont Engineering Polymers Vespel® SP21—15% graphite filled PI.
Figure 7.42.
Wear factor vs. temperature against unlubricated mild carbon steel of two DuPont Engineering Polymers Vespel® SP PI plastics.
Figure 7.43.
Wear rate vs. PV against unlubricated mild carbon steel in thrust bearing tester of DuPont Engineering Polymers Vespel® SP21—15% graphite filled PI.
Figure 7.44.
Wear factor vs. unlubricated counter material hardness in thrust bearing tester of DuPont Engineering Polymers Vespel® SP21—15% graphite filled PI.
Figure 7.45.
Wear factor vs. roughness of unlubricated counter material hardness in thrust bearing tester of DuPont Engineering Polymers Vespel® SP21—15% graphite filled PI.
Table 7.10. Wear and Friction Properties of Several DuPont Engineering Polymers Vespel® PI Plastics