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Dielectric Properties of Functional Polypropylene and Derivatives. Xuepei Yuan, Min Zhang, and Mike Chung Department of Materials Sci. & Eng. Penn State University. BOPP Dielectric ( s -electron polarization ). Advantages and Disadvantages. e = 2.2. High breakdown strength
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Dielectric Properties of Functional Polypropylene and Derivatives • Xuepei Yuan, Min Zhang, and Mike Chung • Department of Materials Sci. & Eng. • Penn State University
BOPP Dielectric (s-electron polarization) Advantages and Disadvantages e = 2.2 • High breakdown strength • Low dielectric loss • Good processibility • Self-healing and low cost • Low dielectric constant • Low energy density P-E loops Simultaneously • Increase dielectric constant • Increase breakdown strength • Maintain low energy loss
Functional Polypropylene and Derivatives Dipolar, Ion Pair, or p-Electrons with Good Polarization Reversibility
PP-H Copolymers PP Flexible alkyl side chains reduce crystallinity, increase irreversible polarization
PP-OH Copolymers Steven Boggs Bob Weiss Fast and Reversible polarization Unexpected large increase in dielectric constant with few% OH groups
PP-OH Derivatives Nonpolar X-linking with p-electrons Ion pair
PP-OSi(CH3)3 Derivative With 4 mol% side chains Silane group removes H-Bonding and reduces e and polarization reversibility
Comparison of PP-H and PP-OSi(CH3)3 With 4 mol% side chains • Flexible side chains reduce crystallinity and polarization reversibility. • H-bonding is needed for reversible polarization.
Cross-linking PP-OH Derivative Gel=100% [OH]=0.6 mol%
PP-O-Na+ Ion-containing Polymer • Ion pair (O-M+) increases polarization (e). • Ion pairs show non-linear polarization and large remnant polarization. • Ion pairs may form ionic cluster (with water?) that slowly reorganize its structure under the electric field.
PP-O-Na+ and PP-O-K+ Ion-containing Polymers PP-O-Na+ PP-O-K+
Brief Summary • Few % OH groups in flexible side chains is sufficient to double PP dielectric constant (e). • 3-D network, either chemical or physical cross-linking by side chains, is essential to exhibit reversible (fast) polarization response. • Ion-containing polymer PP-O-Na+ increases dielectric constant, but reduces the responding speed and creates ferroelectric loss. Other polar groups that can form H-bonding and also ionic pairs. What are the unique features of flexible side chains under the electric field?
Dielectric Properties of PolyalcoholsHomopolymer Rampi Ramprasad Unexpected large dielectric constant and loss
P-E Loops of Polyalcohol Hompolymers 10 Hz Large Ferroelectricity
PP-COOH Copolymers Dielectric Constant P-E loop C1: [COOH]=0.51% C2: [COOH]=0.80% C3: [COOH]=1.13% Overall, PP-COOH results are quite in consistence with PP-OH results
PP-NH2 Copolymers PP-NH2 (2.2%) PP-NH2, 2.2% PP PP Overall, PP-NH2 results are also consistent with PP-OH results
P-E Loop Comparison PP-NH2 (with 0.4 mol% NH2) PP-NH2 (with 1.4 mol% NH2) PP-NH3+Cl- (with 0.4 mol% NH3+Cl-) PP-NH3+Cl- (with 1.4 mol% NH3+Cl-) Ionization of NH2 to NH3+Cl- increases e and slightly reduces the polarization reversibility
Conclusion • Synthesis routes have been developed to prepare a broad range of functional PP polymers and derivatives. • PP-OH, PP-NH2, and PP-COOH copolymers, with few % of polar groups form H-bondings and 3-D network, which increase dielectric constant and reversible polarization (low loss). (breakdown strength?) • Poly(hexenol) homopolymer shows unexpected high dielectric constant and large remnant polarization (large ferroelectricity). • PP ion-containing copolymers show mix dielectric behaviors, PP-NH3+Cl- with fast response, PP-O-Na+with slow response