The Effect of Epoxidation on Strain‐Induced Crystallization of Epoxidized Natural Rubber

Abstract

The effect of epoxidation on strain‐induced crystallization (SIC) of epoxidized natural rubber (ENR) and mechanism are studied with synchrotron radiation wide‐angle X‐ray diffraction (SR‐WAXD) and polarized infrared spectroscopy (P‐IR). WAXD results reveal that appropriate epoxidation, for example, ENR‐25 epoxidized with ≈25% isoprene units, can unexpectedly enhance the SIC of natural rubber (NR), resulting in the improvement of tear resistance. On the other hand, exorbitant epoxidation, for example, ENR‐40 epoxidized with ≈40% isoprene units, depresses the SIC and weakens the mechanical properties of NR remarkably. P‐IR studies reveal that epoxidation can promote the orientation of chain segments along the stretching direction, which plays a determining role on SIC of NR. Accordingly, hierarchical multiscale schematic models are proposed. This insight into epoxidation on SIC of ENR strongly suggests that ENR with appropriate epoxidation degree is a promising candidate material for the fabrication of high‐performance engineering rubber products.

A catalyst-free and recycle-reinforcing elastomer vitrimer with exchangeable links

“…In the other hand, easier extension could lead to more signicant strain-induced crystallization (SIC) effect of the ENR chains. 42 Therefore, the tensile strength of the recycled XNBR-50s was remarkably improved.…”

A high toughness elastomer based on naturalEucommia ulmoidesgum

“…HEUG-23.2% and HEUG-51.2% display an amorphous feature with a broad ring, but sharp diffraction spots appear in the diffraction pattern of HEUG-85.9%. 10 In other words, SIC of HEUG-85.9% occurred at the strain of 400%. It is considered that SIC could change the growth direction of crack, then more energy is required to reach a failure of materials.…”

“…[6][7][8][9] As an important bio-based polymer, natural rubber (NR) is widely used in automotive, national defense, machinery manufacturing, biomedical fields, and so on because of its peerless comprehensive properties, such as high tensile and tear strength, excellent crack growth resistance, and low hysteresis. 10,11 The superior properties of NR are mainly attributed to its self-reinforcement ability related to the strain-induced crystallization (SIC) during stretching. 12,13 However, the ever-increasing demand for NR coupled with the vulnerability of NR production system, and serious allergic reactions to proteins exist in NR have empowered researchers to develop alternative rubber.…”

“…As an important bio‐based polymer, natural rubber (NR) is widely used in automotive, national defense, machinery manufacturing, biomedical fields, and so on because of its peerless comprehensive properties, such as high tensile and tear strength, excellent crack growth resistance, and low hysteresis 10,11 . The superior properties of NR are mainly attributed to its self‐reinforcement ability related to the strain‐induced crystallization (SIC) during stretching 12,13 .…”

Structure Evolution of Epoxidized Natural Rubber (ENR) in the Melt State by Time-Resolved Mechanical Spectroscopy

“…Epoxidized natural rubber (ENR) is a non-fossil fuel-based elastomer derived from the chemical modification of natural rubber (epoxidation) in order to increase the polarity of groups along the polymer chains, while maintaining most of the characteristics of its native counterpart [1][2][3]. Notable among these is the ability of ENR to crystalize under strain up to 50 mol% of epoxidation level and to exhibit "good" mechanical properties [4].…”