Effects of Dynamic Crosslinking on Crystallization, Structure and Mechanical Property of Ethylene-Octene Elastomer/EPDM Blends

Abstract

The dynamic crosslinking method has been widely used to prepare rubber/plastic blends with thermoplastic properties, and the rubber phase is crosslinked in these blends. Both polyolefin elastomer (POE) and ethylene-propylene-diene monomer rubber (EPDM) can be crosslinked, which is different from usual dynamic crosslinking components. In this paper, dynamic crosslinked POE/EPDM blends were prepared. For POE/EPDM blends without dynamic crosslinking, EPDM can play a nucleation role, leading to POE crystallizing at a higher temperature. After dynamic crosslinking, the crosslinking points hinder the mobility of POE chains, resulting in smaller crystals, but having too many crosslinking points suppresses POE crystallization. Synchrotron radiation studies show that phase separation occurs and phase regions form in non-crosslinked blends. After crosslinking, crosslinking points connecting EPDM and part of POE chains, enabling more POE to enter the EPDM phase and thus weakening phase separation, indicates that dynamic crosslinking improves the compatibility of POE/EPDM, also evidenced by a lower β conversion temperature and higher α conversion temperature than neat POE from dynamic mechanical analysis. Moreover, crosslinking networks hinder the crystal fragmentation during stretching and provide higher strength, resulting in 8.3% higher tensile strength of a 10 wt% EPDM blend than neat POE and almost the same elongation at break. Though excessive crosslinking points offer higher strength, they weaken the elongation at break.

Structure–Property Relationships of Shape Memory, Semicrystalline Polymers Fabricated by In Situ Polymerization and Crosslinking of Octadecyl Acrylate/Polybutadiene Blends

“…The greater extent of crosslinking must hinder the arrangement of the side chain grafted polymer into crystals. [ 44,45 ]…”

Novel covalent adaptable networks (CANs) of ethylene/1-octene copolymers (EOCs) made by free-radical processing: comparison of structure–property relationships of EOC CANs with EOC thermosets

“…14,15 These strong, physical cross-links provide EOCs with elasticity and strength, and EOCs are desirable as low-cost impact modifiers and tougheners in thermoplastic elastomers, foams, and shape memory polymers for applications like footwear, cushioning, and catheters. [16][17][18][19][20][21][22][23] EOCs are common components in blends with other polymers such as polypropylene (PP), [24][25][26][27][28] ethylene propylene diene monomer (EPDM) rubber, [29][30][31][32] ethylene-vinyl acetate copolymer (EVA), [33][34][35] and polydimethylsiloxane (PDMS). 36,37 Like PE, EOCs and their blends may be vulcanized or covalently crosslinked using radical initiators such as peroxides to enhance properties like elasticity and temperature resistance.…”

A Polyolefin Elastomer Encapsulant Modified by an Ethylene–Propylene–Diene Terpolymer for Photovoltaic Applications

“…The mechanical behavior between the uncross-linked and cross-linked POE films was characterized using tensile tests, and the results are presented in Figure . According to the literature, the addition of a small amount (10 wt %) of EPDM into the POE matrix does not significantly affect to the instinctive mechanical properties of the uncross-linked and cross-linked compounds. In the case of uncross-linked film samples, the remarkable changes in ultimate properties were not detected with an increasing m -EPDM content.…”