Paper Number
SM22 

Session
Polymer Solutions & Melts

Title
Strain hardening in immiscible PE/PP blends via interfacial reinforcement with PE-cb-PP comb-block copolymers

Presentation Date and Time
February 14, 2017 (Tuesday) 2:20

Track / Room
Track 5 / Snowy Egret

Authors (Click on name to view author profile)

1. López-Barrón, Carlos R. (ExxonMobil Chemical Company)
2. Tsou, Andy (ExxonMobil Chemical Company)
3. Jiang, Peijun (ExxonMobil Chemical Company)
4. Crowther, Donna (ExxonMobil Chemical Company)

Author and Affiliation Lines (in printed abstract book)
Carlos R. López-Barrón, Andy Tsou, Peijun Jiang, and Donna Crowther
ExxonMobil Chemical Company, Houston, TX

Speaker / Presenter 
López-Barrón, Carlos R.

Text of Abstract
Poly(ethylene-cb-propylene) (P(E-cb-P)), prepared by copolymerization of vinyl terminated atactic polypropylene and ethylene [Tsou et al., Polymer 104, 72-82 (2016)] was used to compatibilize immiscible blends of high density polyethylene (HDPE) and isotactic polypropylene (iPP). Addition of 5 wt% P(E-cb-P) resulted in microdomain size reductions and the concomitant increase in the elastic modulus, as typically observed in immiscible blends compatibilized with linear block copolymers. A more intriguing phenomena is the development of extensional strain hardening by the addition of P(E-cb-P) to the HDPE/iPP blends. This effect is stronger in blends with cocontinuous microstructure (50/50 HDPE/iPP) than in blends with matrix-droplet morphology (75/25 or 25/75 HDPE/iPP). We postulate that the enhancement in strain hardening observed in the compatibilized blends is due to strengthening of the interface via two mechanisms: (1) the increase in the blend interfacial area and (2) entanglement of the PE and PP blocks from P(E-cb-P) within the corresponding homopolymer phases.