Adel F. Halasa, Ph.D. University of Akron College of Polymer Science Solution Blend Study Study of Compatibility and Miscibility of Polymers and Copolymers on Butadiene and Isoprene October 14-16, 2014 Nashville Convention Center, Nashville, TN Adel F. Halasa, Ph.D. University of Akron College of Polymer Science

Objective A series of solution blends at different compositions were prepared to determine the compatibility and miscibility of polymers based on 3,4PI, MvPBd, HvPBd, and IBR.

Background Polymer Blends Prepared in solution Compared against themselves and the controls Conclusions based on experimental information

Introduction Consideration for the development of tire elastomers Traction = f (Tg, low temp., stiffness, etc) Treadwear = f (Tg, molecular weight, polymer-filler interaction, etc) Rolling resistance = f (Tg, branching, molecular weight, filler interaction, etc) Processibility = f (molecular weight/distribution, branching, etc)

Monomer Composition/Microstructure is a primary Polymer Compounds Primary Selection Criterion: Glass Transition Temperature Monomer Composition and Microstructure ==> Polarity, Blend Miscibility ==> basic viscoelastic response ==> RR, WS, TW Secondary Selection Criteria: Molecular Weight ==> RR/WS balance, Network Structure, Filler incorporation and dispersion Tertiary Selection Criteria: Molecular Weight Distribution Coupling, Functionality, Tacticity, Blockiness … ==> Fine Tuning Monomer Composition/Microstructure is a primary selection criterion.

Tg/Polarity Rubber Map S-SSBR: Increased Tg achievable with high and low polarity substituents

Blends MVPBd (1,2V 50%)/( 3,4-PI 87%) (HVPBd 1,2 V 80%)/(3,4-PI 87%) IBR (50/50)/(3,4-PI 87%) IBR(50/50)/(HVPBd 1,2V 80%)

Test Conditions DSC DMA TGA RPA -140 to 40 @ 10 C/min RPA 507 @ 100 C

Miscibility Measurement by DSC DSC is a suitable tool for measuring miscibility of polymers - applicable to polymers with Tg difference > = 10 oC - resolves polymer domains > 150 Å Combining two polymers A and B with narrow Tg’s defined by a difference between onset and end point of 10C: ==> immiscible blend, if Tgs’s of polymers A and B are unchanged ==> miscible blend, if single narrow Tg located between pure polymer Tg’s ==> partially miscible blend, if two approached narrow Tg’s (co-existence of two mixed phases, distinct boundaries in TEM) if one braodened Tg over tempearture range located between pure polymer Tg’s (co-existence of multiple mixed phases, diffuse boundaries in TEM) Same principle applicable with Torsion Pendulum (G’, G”, Tan D)

Controls MvPBd 3,4-PI HvPBd 80% high vinyl polybutadiene IBR 50% medium vinyl polybutadiene 3,4-PI high 3,4 tapered polyisoprene HvPBd 80% high vinyl polybutadiene IBR 50/50 tapered IBR

Thermal Properties of Base Rubbers Tg (DSC) Tg (target) Tg (DMA) Decomp. Temp (TGA) MvPBd -61.0 -60.0 -42.8 423.6 HvPBd -32.2 -28.0 -12.4 444.2 IBR -45.3 -47.0 -24.1 406.4 3,4 PI -18.0 -12.0 -2.6 323.4

MvPBd/3, 4PI Ratios: 90/10, 70/30, 50/50, 30/70, 10/90 Tests: DSC, DMA, TGA, RPA See Table for data

Thermal Properties of MvPBd/3,4 PI Blends Tg (DSC) Tg (DMA) Decomp. Temp (TGA) 90/10 -62.2 --------- -44.6 422.9 70/30 -61.2 -18.1 -42.5 -0.2 331.8 50/50 -62.8 -20.4 -4.9 356.8 30/70 -21.3 -48.8 -3.0 323.4 10/90 -63.0 -19.5 -51.0 -3.7 338.2 TwoTg’s from both the DMA and the DSC for all blends except for 90/10 MvPBd/3, 4 PI IMMISCIBLE

Summary MvPBd/3, 4 PI Two distinct glass transition temperatures shows that they are immiscible. The TGA reveals that medium vinyl does not stabilize 3,4 polyisoprene.

HvPBd/3,4PI Ratios: 90/10, 70/30, 50/50, 30/70, 10/90 Tests: DSC, DMA, TGA, RPA, TEM See Table for data

Thermal Properties of HvPBd/3,4 PI Blends Tg (DSC) Tg (DMA) Decomp. Temp (TGA) 90/10 -30.3 -13.9 70/30 -30.1 -5.5 430.2 50/50 -24.5 -4.3 418.4 30/70 -21.9 -0.1 406.9 10/90 -17.3 1.4 only one Tg in both the DSC and DMA tests MISCIBLE

Thermal Properties of HvPBd/3,4 PI Blends

Summary HvPBd/3, 4PI TEM shows a small domain and two phase morphology. A broad, single peak was observed in the DMA test revealing that HvPBd and 3, 4 PI are truly compatible. The TGA surprisingly reveals that HvPBd stabilizes 3, 4PI, preventing the decomposition of 3,4 polyisoprene.

IBR/3,4 PI Ratios: 70/30, 50/50, 30/70 Tests: DSC, DMA, TGA, RPA See Table for data

Thermal Properties of IBR/3,4 PI Blends Tg (DSC) Tg (DMA) Onset decomp. temp (TGA) 70/30 -45.6 -17.1 -22.8 0.4 390.39 50/50 -44.8 -17.0 -30.2 -1.6 375.25 30/70 -45.5 -19.1 -29.5 -3.6 341.61 TwoTg’s from both the DMA and the DSC for all blends IMMISCIBLE

Summary IBR/3, 4PI The addition of IBR to 3, 4PI shows that they are compatible. The TGA shows that IBR enhances thermal stability of 3, 4 PI.

IBR/HvPBd Ratios: 70/30, 50/50, 30/70 Tests: DSC, DMA, TGA, RPA, TEM See Table for data

Thermal Properties of IBR/HvPBd Blends Tg (DSC) Tg (DMA) Decomp. Temp (TGA) 70/30 -42.0 -20.1 416.9 50/50 -40.8 -19.2 429.95 30/70 -37.0 -18.8 431.9 one Tg for both the DMA and DSC MISCIBLE rod-like and lamellar structures

Summary IBR/HvPBd One Tg is observed in both the DMA and DSC tests. The TGA shows a small improvement in the thermal stability of IBR. The observed results from TEM show the blends are compatible, but there may be some miscible areas or “phase mixing.”

Conclusion MvPBd/3, 4 PI: - Two distinct glass transition temperatures, immiscible. - Medium vinyl does not stabilize 3,4 PI. HvPBd/3, 4 PI: - A single Tg, suggesting miscibility between HvPBd - A broad, single peak was observed in the DMA test revealing that HvPBd and 3,4 PI are highly compatible. - HvPBd stabilizes the3,4 PI and acts as a radical trap, preventing the decomposition of 3,4 polyisoprene. IBR/3,4PI: - Compatible. - High amounts of IBR, thermal stability is improved. IBR/HvPBd: - only one Tg, some miscible areas or “phase mixing.” - small improvement in the thermal stability of IBR.

Forward Program Suggestions were made to run the RPA at room temperature to determine the G’ and tan delta values at the rubber plateau region. Solubility parameters of the controls were requested. The TGA will be run on 30/70 Sn-coupled IBR, 30/70 IBR , and both 90/10 and 10/90 MvPBd/3,4 PI. The DSC will be run again on 90/10 MvPBd/3, 4 PI to determine if two Tg’s are present.

Acknowledgement The author would like to thank Dr. Kwang Su Seo for his comments and suggestions. The Goodyear Tire and Rubber Company for providing all the samples used in this study.