Enhancing Toughness and Flame Retardancy of Epoxy Thermosets Using SEBS-g-PEG/DOPO Blends

Muhammad Sajjad; Muhammad Kamran; Salman Qadir; Karuppathevan Ramki; Sivadasan Dharani; Shao Tao Bai

doi:10.1002/pen.70232

Enhancing Toughness and Flame Retardancy of Epoxy Thermosets Using SEBS-g-PEG/DOPO Blends

Muhammad Sajjad^*
, Muhammad Kamran
, Salman Qadir^*
, Karuppathevan Ramki
, Sivadasan Dharani
, Shao Tao Bai^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

Enhancing the flame retardancy and toughness of epoxy thermosets without compromising glass transition temperature (T_g) or mechanical strength is a critical challenge. In this study, the graft copolymer, SEBS-g-PEG was prepared by chemically grafting polyethylene glycol (PEG) to the terminal blocks of polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SEBS). These block copolymers (BCPs) along with various loading levels of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were covalently incorporated into the epoxy thermosets to enhance their properties. The resulting composites exhibited excellent matrix compatibility, achieving up to a 200% improvement in fracture toughness and a 70% increase in flame retardancy at higher DOPO loadings (e.g., 8 wt%) without plasticizing effects. Notably, T_g and tensile strength were preserved, enabling balanced high-performance composites.

Original language	English
Pages (from-to)	487-496
Number of pages	10
Journal	Polymer Engineering and Science
Volume	66
Issue number	1
DOIs	https://doi.org/10.1002/pen.70232
State	Published - Jan 2026
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2025 Society of Plastics Engineers.

Keywords

9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)
epoxy thermoset
flame retardant
toughening

ASJC Scopus subject areas

General Chemistry
General Engineering
Polymers and Plastics
Materials Chemistry

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10.1002/pen.70232

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title = "Enhancing Toughness and Flame Retardancy of Epoxy Thermosets Using SEBS-g-PEG/DOPO Blends",

abstract = "Enhancing the flame retardancy and toughness of epoxy thermosets without compromising glass transition temperature (Tg) or mechanical strength is a critical challenge. In this study, the graft copolymer, SEBS-g-PEG was prepared by chemically grafting polyethylene glycol (PEG) to the terminal blocks of polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SEBS). These block copolymers (BCPs) along with various loading levels of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were covalently incorporated into the epoxy thermosets to enhance their properties. The resulting composites exhibited excellent matrix compatibility, achieving up to a 200\% improvement in fracture toughness and a 70\% increase in flame retardancy at higher DOPO loadings (e.g., 8 wt\%) without plasticizing effects. Notably, Tg and tensile strength were preserved, enabling balanced high-performance composites.",

keywords = "9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), epoxy thermoset, flame retardant, toughening",

author = "Muhammad Sajjad and Muhammad Kamran and Salman Qadir and Karuppathevan Ramki and Sivadasan Dharani and Bai, \{Shao Tao\}",

note = "Publisher Copyright: {\textcopyright} 2025 Society of Plastics Engineers.",

year = "2026",

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doi = "10.1002/pen.70232",

language = "English",

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T1 - Enhancing Toughness and Flame Retardancy of Epoxy Thermosets Using SEBS-g-PEG/DOPO Blends

AU - Sajjad, Muhammad

AU - Kamran, Muhammad

AU - Qadir, Salman

AU - Ramki, Karuppathevan

AU - Dharani, Sivadasan

AU - Bai, Shao Tao

PY - 2026/1

Y1 - 2026/1

N2 - Enhancing the flame retardancy and toughness of epoxy thermosets without compromising glass transition temperature (Tg) or mechanical strength is a critical challenge. In this study, the graft copolymer, SEBS-g-PEG was prepared by chemically grafting polyethylene glycol (PEG) to the terminal blocks of polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SEBS). These block copolymers (BCPs) along with various loading levels of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were covalently incorporated into the epoxy thermosets to enhance their properties. The resulting composites exhibited excellent matrix compatibility, achieving up to a 200% improvement in fracture toughness and a 70% increase in flame retardancy at higher DOPO loadings (e.g., 8 wt%) without plasticizing effects. Notably, Tg and tensile strength were preserved, enabling balanced high-performance composites.

AB - Enhancing the flame retardancy and toughness of epoxy thermosets without compromising glass transition temperature (Tg) or mechanical strength is a critical challenge. In this study, the graft copolymer, SEBS-g-PEG was prepared by chemically grafting polyethylene glycol (PEG) to the terminal blocks of polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SEBS). These block copolymers (BCPs) along with various loading levels of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were covalently incorporated into the epoxy thermosets to enhance their properties. The resulting composites exhibited excellent matrix compatibility, achieving up to a 200% improvement in fracture toughness and a 70% increase in flame retardancy at higher DOPO loadings (e.g., 8 wt%) without plasticizing effects. Notably, Tg and tensile strength were preserved, enabling balanced high-performance composites.

KW - 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)

KW - epoxy thermoset

KW - flame retardant

KW - toughening

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M3 - Article

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SN - 0032-3888

VL - 66

SP - 487

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JO - Polymer Engineering and Science

JF - Polymer Engineering and Science

IS - 1

ER -

Enhancing Toughness and Flame Retardancy of Epoxy Thermosets Using SEBS-g-PEG/DOPO Blends

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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