Nano-materials in Polymer Composites for High-Volume Applications Kyriaki Kalaitzidou Associate Professor G.W. Woodruff School of Mechanical Engineering and School of Materials Science and Engineering Georgia Institute of Technology RBI Executive Conference March 2015
What do we do? GOAL Utilize the unique properties of nano-materials in order to introduce multifunctionality into i) polymers (polymer nanocomposites) ii) traditional polymer composites (hybrid composites) OBJECTIVES Understand the processing-structure-property relationship in nanoreinforced polymers Identify the reinforcing mechanisms and the correlations between macroscopic properties and nano/micro- scale phenomena Demonstrate the multifuntionallity of polymer nanocomposites and the synergistic effects on hybrid composites Design composites with engineered properties 2
Why Polymer Nanocomposites? Nanomaterials can significantly alter the polymer properties even at low content (less than 5 wt%) Lightweight structures (10% mass reduction results in 6% fuel efficiency) Enhanced modulus and strength Reduced CTE Engineered electrical conductivity (static dissipation, elimination of primer during electrostatic painting) Engineered thermal conductivity (heat dissipation) Versatile and scalable processing/manufacturing
Background Nanomaterials + Unique properties due to their high surface area and small size + Used as reinforcements in polymers or as coatings of GF or CF enhancing the fiber/polymer interface + Available in various shapes, aspect ratios and intrinsic properties - Homogeneous dispersion and uniform distribution is challenging - Processing can alter their shape/size, orientation, location Manufacturing Processes Be scalable (no need for toxic/exotic chemicals, economic) Allow for controlled placement/orientation of the nanomaterials Be able to create parts with complex geometries and functional graded materials in a single step process
Nanomaterials Used xgnp CNT CB BaTiO 3 VGCF Platelets Tubes spherical spheres fibers 0.8mm 5-10mm aggregates > 2mm 50-100mm 10-20nm 20-30nm ~0.5 mm 30-50 nm 150nm xgnp (side view) CB VGCF
Compounding: How nanomaterials are added to the polymer Compounding Coating Melt-mixing Solution mixing Solid state mixing side view of GNP 5nm top view of GNP 25µm Sonication of GNP solution a) + Isopropyl + alcohol Polymer powder b) Polymer powder coated with GNP
Manufacturing: Thermoplastic Polymers Manufacturing Injection molding Compression Molding Selective laser sintering
Manufacturing: Thermoset Polymers Typical SMC line 8
SMC Pilot Line at GaTech 9
The role of nanomaterials in polymer composites Hypothesis: Addition of graphite nanoplatelets (GNP) in glass fiber (GF) polymer composites can improve the GF-polymer interfacial interactions and thus the mechanical properties and decrease the composite s density Materials and Approach: Polymers: PP Epoxy Way GNP were introduced to the composite: Mixed in the polymer As fiber coating Lab scale manufacturing
GF/PP composites: Interfacial properties Single fiber fragmentation test Microdebonding test GNP and PPgMA result in similar increase in ISS Significant ISS enhancement when using GNP-coated GF Highest ISS when using both GNP and PPgMA in PP matrix
Tensile modulus of GNP / GF /PP hybrid composites - Ramp tensile test by tens. testing machine INSTRON 33R 4466, cross-head speed = 5 mm/min - Strain measured by an extensometer - Five dog-bones specimens for each sample 3.30 x 3.27 mm 2
Tensile properties and impact stength of GNP / GF /PP hybrid composites 3.30 x 3.27 mm 2 Industrial Reference Hybrid density 8.4 %
Morphology of GF / PP composites 10GF / PP 10GFc / PP 5GNP / 10GF / PP 30 μm 30 μm 30 μm 3 μm 8 μm 3 μm - Bench-top SEM (Phenom G2 Pro,Phenom-World BV) - Accelation Voltage= 5kV - Gold coating by plasma sputtering prior to observations 14
GNP/GF/Epoxy Composites 15
Morphology of GNP/GF/Epoxy Composites Neat epoxy 5 wt% GNP 10 wt% GF 5 wt% GNP+10wt% GF Interfacial debonding as dominant fracture mechanism in 10GF/epoxy Matrix crack becomes a concurrent failure mechanism in hybrid comp.
Tensile properties of GNP/GF/Epoxy Composites
Tensile properties of GNP/GF/Epoxy Composites Sample E [MPa] E* [MPa/(g/cm 3 )] epoxy 2917 ± 37 (2537) 5GNP/epoxy 3543 ± 76 (3023) 10GF/epoxy 3793 ± 40 (3122) 30GF/epoxy 4266 ± 80 (3111) 5GNP/10GF/epoxy 3907 ± 74 (3156) 5GNP/15GF/epoxy 4178 ± 91 (3282) 10GFc/epoxy 3818 ± 65 (3140) 5GNP/10GFc/epoxy 3949 ± 47 (3189) Hybrid vs traditional composites Better specific properties Comparable strain at break Slightly lower impact strength σ B [MPa] σ B * [MPa/(g/cm 3 )] 59.6 ± 0.7 51.8 62.4 ± 0.2 (53.2) 63.7 ± 0.3 (52.4) 67.8 ± 0.2 (49.5) 67.0 ± 0.6 (54.2) 70.4 ± 0.7 (55.3) 64.7 ± 0.2 (53.2) 67.9 ± 0.2 (54.8) ε B [%] Izod impact strength [J/m] 4.1 ± 0.1 26.5 ± 2.1 3.5 ± 0.1 28.6 ± 1.4 3.1 ± 0.2 80.5 ± 2.3 2.0 ± 0.2 116.2 ± 2.4 3.0 ± 0.2 92.4 ± 1.9 2.2 ± 0.2 107.5 ± 1.9 3.0 ± 0.2 86.4 ± 1.4 2.8 ± 0.2 101.4 ± 1.1
Current P3 Nano Project: Research Key Questions Hypothesis: Addition of NC in GF/epoxy composites made using SMC technology should result in Improvement or no compromise of the mechanical properties Density reduction Questions to be addressed: What is the optimum amount of CN What is the optimum type of CN How CN will be added into the GF/epoxy composite? Add CN in the polymer matrix Coat the GF with CN Do both of the above 19
Research Key Questions Addition of CN into the epoxy: Disperse CN in aqueous solution add epoxy Challenges: not very compatible, not easily scalable, Issues with resin s viscosity Spray CN solution using a robotic arm into the GF/resin layer in the SMC line Challenges, controlling CN wt% Coat GF with CN 20
Initial Approach 21
Conclusions Understanding the processing-structure-property relationship and revealing the mechanisms responsible for the property enhancement in polymers or/and composites reinforced with nanomaterials can reduce the commonly used trial and error approach and lead to systematically engineer the properties of polymer composites for targeted applicationsusing large scale manufacturing processes
Acknowledgements Group Members: Dr Amir Asadi Erin Sullivan Matthew Smith Sanzida Sultana Shaun Eshraghi Diego Pedrazzoli (Ph.D 2014) Siddharth Athreya (Ph.D. 2010) Atiq Bhuiyan (Ph.D. 2013) Mehdi Karevan (Ph.D. 2013) Brian Simpson (MS 2010) Brian Kwong (MS 2014) Chu Chun (MS 2010) Collaborators Prof. Suman Das Prof. Ben Wang Prof. Bara Cola Prof. Asegun Henry Prof. Alex Alexeev Prof. Antonia Antoniou Prof. Surya Kalindidi Dr Robert Moon (US Forestry) Dr Raghu Pucha