Coupling Additive For Vinyl Ester / Carbon Fiber Composites
Brian KleinheinzTechnical Service Manager – ThermosetBYK USASPE Automotive Composites Conference and ExhibitionSeptember 4-6 2019Novi, MI
Coupling Additives
BYK-C 8013
A solvent-free polymeric additive that increases the mechanical
strength of carbon fiber-reinforced radical-curing systems
Unsaturated Polyester and Vinyl Ester in Carbon-Fiber Reinforced Plastics (CFRP)
Advantages of Unsaturated Polyester / Vinyl Ester systems:
• Low cost
• 1-component processability
• Lower viscosity
• Corrosion resistance (VE)
• Easier adjustment of curing speed
Suitable application methods
• Sheet molding / Bulk molding compounds (SMC/BMC)
• Pultrusion
• Resin-transfer molding (RTM)
• Pre-preg
Theory of
Coupling Agents
TheoryAdhesion: Product Design
Improved bonding between substrate/fiber and resin with a specific
molecule with resin reactive and substrate/fiber reactive groups
Resin reactive
Group
Polymeric Resin
Compatible Group
Substrate/Fiber
Reactive Groups
TheoryAdhesion: Coupling
Resin Matrix Fiber
R
Chemical Bonds!
R
Coupling Additive
TheoryAdhesion: Coupling
Coupling Additive for Vinyl ester / Carbon fiber Composites -SEM micrograph
SEM with 5% coupling agent on
CF after failure
SEM without additive after
failure
Coupling
effect
No
coupling
effect
Fracture of a CFRP incorporating this
coupling agent show significant residual
resin indicating a strong bond
Fiber fracture shows the strength of the
resin/fiber bond
Application of the Coupling Agent
Application
How can the coupling agent be applied?
1. in the Carbon fiber sizing bath
3. in the resin system
1 Sizing bath
2 2nd Sizing
3 In resin
Application as a second sizing
NEW VIDEO!!!
Performance Results
Vinyl Ester SMC
Vinyl ester / Carbon fiber CompositesVE compatible Carbon fiber fabric
Fabric:
N-C-416g/m², 12K
Fiber weight content: 55%
Application:
Second Sizing
5% Coupling agent on
carbon fiber
Transverse Tensile Strength (MPa)Transver Flexural Strength (MPa)
Improvement of mechanical properties, flexural and transverse tensile
strength up to 70%
0
10
20
30
40
50
60
Control Coupling agent Control Coupling agent
+67%
+55%
0.0
10.0
20.0
30.0
40.0
50.0
60.0
Control Coupling Agent Control Coupling Agent
+ 36%
+ 45%
Vinyl ester / Carbon fiber CompositesEP compatible Carbon fiber fabric
Application:
Second Sizing
5% Coupling agent on
carbon fiber
Fabric:
U-C-882g/m², 50K
Fiber weight content: 55%
Transverse Flexural Strength (Mpa) Transverse Tensile Strength (Mpa)
Can be applied onto any Carbon fiber
Vinyl ester / Carbon fiber Composites Chopped Carbon fiber SMC
Fiber:
12K
Fiber weight content: 52%
Application:
5% Coupling agent on resin
SMC-formulation
Mold coverage: 40%
Transverse Flexural strength (Mpa) Tensile Strength (Mpa)
Improvement of mechanical properties in chopped Carbon fiber SMC
0
50
100
150
200
250
300
350
400
450
Control Coupling agent Control Coupling agent
+18%
+30%
Performance Enhancement
Unsaturated Polyester SMC
Coupling agent can elevate unsaturated polyester SMC performance above standard Vinyl Ester SMC
15
20.4
27.2
0
5
10
15
20
25
30
UP Panel VE control Coupling Agent
Transverse tensile strength (MPa)
33
36
49.3
0
10
20
30
40
50
60
UP Panel VE Control Coupling agent
Transverse Flexural Strength (MPa)
Performance Enhancement
Improvement in part strength with a reduction of thickness and weight
Improving part strength while reducing thickness
0
10
20
30
40
50
60
Control - 4Layers
Control - 2Layers
5% CAapplied tofiber - 2layers
5% CA inresin - 2layers
Transverse Flexural Strength (MPa)
0
1000
2000
3000
4000
5000
6000
Control - 4Layers
Control - 2Layers
5% CAapplied tofiber - 2layers
5% CAadded toresin - 2layers
Transverse Flexural Modulus (MPa)
Improving part strength while reducing thickness
0
5
10
15
20
25
30
35
Control - 4layers
Control - 2layers
5% CAapplied tofiber - 2layers
5% CA inresin - 2layers
Transverse Tensile Strength (MPa)
0
1000
2000
3000
4000
5000
6000
Control - 4Layers
Control - 2Layers
5% CAapplied tofiber - 2layers
5% CAadded toresin - 2layers
Transverse Tensile Modulus (MPa)
Performance over Time
Product Stability
No decrease in performance when fabric is treated and stored
0
10
20
30
40
50
60
1 week 4 weeks 8 weeks
Transverse Flexural Strength (MPa)
Control Coupling agent
0
10
20
30
40
50
60
1 week 4 weeks 8 weeks
Transverse tensile strength (MPa)
Control Coupling agent
No decrease in performance over time when coupling agent added to resin then stored
0
10
20
30
40
50
60
70
direct 1 week 4 weeks
Transverse Tensile Strength (MPa)
Control Coupling agent
0
10
20
30
40
50
60
70
1 week 4 weeks 8 weeks
Transverse Flexural Strength (MPa)
Control Coupling agent
Summary
Coupling agent summary
• Designed for:
• SMC/BMC, Pultrusion, RTM, Pre-preg
• Mechanical properties increased up to 70%
• Improved Quality
• Works with any VE/UP resin system
• Works with any carbon fiber
• Can reduce part weight by allowing less material
• Ensures a constant high quality of the finished part
• Easy handling
• Liquid additive, easy incorporation
• Applicable at any stage of composite production
• Sizing bath
• Applied as 2nd Sizing
• Directly in resin system
Acknowledgements
Dr. René Nagelsdiek
Head of R&D Organic Rheology Additives
Lee R. Gunning
Head of Technical Service Advanced Composites
Thank you for your attention
