With the rising demand for structural materials, epoxy resins are widely used despite their low toughness. This study explores enhancing toughness through epoxidized styrene-butadiene-styrene (eSBS). Three types of SBS were examined: Calprene C501 (linear; 17.5% and 25.8% epoxidation), Solprene S4318 (linear, polydispersed; 21% and 34%), and Solprene S9618 (multi-arm; 21% and 38%), with samples at 5 wt% and 10 wt% per epoxidation level. Findings indicate that eSBS effectively promotes shear yielding when the epoxidation degree is above 21%. The toughening mechanisms vary with molecular characteristics. SBS with a smaller radius of gyration promoted a higher strain at break due to the formation of more aligned shear bands, whereas SBS with a larger radius of gyration tended to form interconnected networks within the matrix, thereby delaying yielding failure. This study highlights the importance of block copolymer properties in optimizing epoxy toughness.
SuCCWooEM. Cure kinetics and morphology of amine-cured tetraglycidyl-4, 4′-diaminodiphenylmethane epoxy blends with poly (ether imide). Polymer1995; 36(15): 2883–2894.
4.
ChenYSLeeJSYuTL, et al.The curing reaction of poly (ether‐sulfone)‐modified epoxy resin. Macromol Chem Phys1995; 196(11): 3447–3458.
5.
DaiZShiFZhangB, et al.Effect of sizing on carbon fiber surface properties and fibers/epoxy interfacial adhesion. Appl Surf Sci2011; 257(15): 6980–6985.
6.
SchmidtRGBellJP (1986). Epoxy adhesion to metals epoxy resins and composites II ed K dusek. https://scholar.google.com
7.
DrzalLTRichMJLloydPF. Adhesion of graphite fibers to epoxy matrices: I. The role of fiber surface treatment. J Adhes1983; 16(1): 1–30.
8.
DrzalLTRichMJKoenigMF, et al.Adhesion of graphite fibers to epoxy matrices: II. The effect of fiber finish. J Adhes1983; 16(2): 133–152.
9.
SultanJNLaibleRCMcGarryFJ. Microstructure of two-phase polymers. Polym. Symp1971; 16: 127–136. https://scholar.google.com
10.
ManzioneLTGillhamJKMcPhersonCA. Rubber‐modified epoxies. I. Transitions and morphology. J Appl Polym Sci1981; 26(3): 889–905.
11.
ManzioneLTGillhamJKMcPhersonCA. Rubber‐modified epoxies. II. Morphology and mechanical properties. J Appl Polym Sci1981; 26(3): 907–919.
12.
ChenTKJanYH. Fracture mechanism of toughened epoxy resin with bimodal rubber-particle size distribution. J Mater Sci1992; 27: 111–121.
13.
KinlochAJShawSJTodDA, et al.Deformation and fracture behaviour of a rubber-toughened epoxy: 1. Microstructure and fracture studies. Polymer1983; 24(10): 1341–1354.
14.
BucknallCBYoshiiT. Relationship between structure and mechanical properties in rubber‐toughened epoxy resins. Br Polym J1978; 10(1): 53–59.
15.
KönczölLDöllWBuchholzU, et al.Ultimate properties of epoxy resins modified with a polysiloxane–polycaprolactone block copolymer. J Appl Polym Sci1994; 54(6): 815–826.
16.
LipicPMBatesFSHillmyerMA. Nanostructured thermosets from self-assembled amphiphilic block copolymer/epoxy resin mixtures. J Am Chem Soc1998; 120(35): 8963–8970.
17.
CooperSLHuhDSMorrisWJ. Stress-softening in crosslinked block copolymer elastomers. Ind Eng Chem Prod Res Dev1968; 7(4): 248–251.
18.
WangLChenJ. Block copolymer elastomer catheter balloons. World intellectual property organization publ.of the int.Appl. with int.search report WO1995US02717. 02 Mar 1995. https://www.freepatentsonline.com/20070197961.pdf
KanaokaSGrubbsRH. Synthesis of block copolymers of silicon-containing norbornene derivatives via living ring-opening metathesis polymerization catalyzed by a ruthenium carbene complex. Macromolecules1995; 28(13): 4707–4713.
21.
DoiYWatanabeYUekiS, et al.Synthesis of a propylene‐tetrahydrofuran block copolymer via “living” coordination polymerization. Makromol Chem, Rapid Commun1983; 4(8): 533–537.
22.
AidaTInoueS. Living polymerization of epoxides with metalloporphyrin and synthesis of block copolymers with controlled chain lengths. Macromolecules1981; 14(5): 1162–1166.
23.
IijimaTSatoKFukudaW, et al.Toughening of epoxy resins by N‐phenylmaleimide‐N‐cyclohexylmaleimide–styrene terpolymers. J Appl Polym Sci1993; 48(10): 1859–1868.
24.
WuQIXuJYuY. Novel dibutyltin oxide‐tributyl phosphate condensate as accelerator for the curing of the epoxy resin/4, 4′‐diamino diphenyl sulfone system. II. Toughening of the resin with hydroxyl‐terminated poly (tetramethylene) glycols. J Appl Polym Sci2001; 80(8): 1237–1242.
25.
WuJThioYSBatesFS. Structure and properties of PBO–PEO diblock copolymer modified epoxy. J Polym Sci B Polym Phys2005; 43(15): 1950–1965.
26.
GeorgeSMPugliaDKennyJM, et al.Reaction-induced phase separation and thermomechanical properties in epoxidized styrene-block-butadiene-block-styrene triblock copolymer modified epoxy/DDM system. Ind Eng Chem Res2014; 53(17): 6941–6950.
27.
SerranoETercjakAKortaberriaG, et al.Nanostructured thermosetting systems by modification with epoxidized styrene− butadiene star block copolymers. Effect of epoxidation degree. Macromolecules2006; 39(6): 2254–2261.
28.
GeorgeSMPugliaDKennyJM, et al.Morphological and mechanical characterization of nanostructured thermosets from epoxy and styrene-block-butadiene-block-styrene triblock copolymer. Ind Eng Chem Res2013; 52(26): 9121–9129.
29.
ChongHMTaylorAC. The microstructure and fracture performance of styrene–butadiene–methylmethacrylate block copolymer-modified epoxy polymers. J Mater Sci2013; 48: 6762–6777.
30.
PearsonRBacigalupoLLiangY, et al.Plastic zone size—Fracture toughness correlations in rubber-modified epoxies. In: Proceedings of the 31st Annual Meeting of the Adhesion Society. The Adhesion Society, 2008, vol 17. https://scholar.google.com
31.
OrtizCMcDonoughWHunstonD, et al. The effect of concentration and particle size on the fracture toughness of epoxies modified with dispersed acrylic elastomers. Proc. ACS: Polym Mater Sci Eng. 1994; 70(9). https://scholar.google.com.
32.
JiangYZhaoRXiZ, et al.Improving toughness of epoxy asphalt binder with reactive epoxidized SBS. Mater Struct2021; 54: 145.
33.
PanditRYoussefBSaiterJM, et al.Investigations into morphology and mechanical properties of epoxidized polystyrene/polybutadiene/polystyrene (SBS) triblock copolymer. J Nepal Chem Soc2011; 28: 42–47.
34.
BagheriRMaroufBTPearsonRA. Rubber-toughened epoxies: a critical review. Polym Rev2009; 49(3): 201–225.
35.
PearsonRAYeeAF. Influence of particle size and particle size distribution on toughening mechanisms in rubber-modified epoxies. J Mater Sci1991; 26: 3828–3844.
36.
IijimaTYoshiokaNTomoiM. Effect of cross-link density on modification of epoxy resins with reactive acrylic elastomers. Eur Polym J1992; 28(6): 573–581.
37.
HongSGChanCK. The curing behaviors of the epoxy/dicyanamide system modified with epoxidized natural rubber. Thermochim Acta2004; 417(1): 99–106.
38.
WuS. Phase structure and adhesion in polymer blends: a criterion for rubber toughening. Polymer1985; 26(12): 1855–1863.
39.
RatnaD. Phase separation in liquid rubber modified epoxy mixture. Relationship between curing conditions, morphology and ultimate behavior. Polymer2001; 42(9): 4209–4218.
40.
SueHJGarcia-MeitinEIPickelmanDM, et al. (1993). Optimization of mode-I fracture toughness of high-performance epoxies by using designed core-shell rubber particles. https://doi.org/10.1021/ba-1993-0233.ch010
41.
BagheriRPearsonRA. Role of particle cavitation in rubber-toughened epoxies: 1. Microvoid toughening. Polymer1996; 37(20): 4529–4538.
42.
CrawfordELesserAJ. Mechanics of rubber particle cavitation in toughened polyvinylchloride (PVC). Polymer2000; 41(15): 5865–5870.
43.
BucknallCBKarpodinisAZhangXC. A model for particle cavitation in rubber-toughened plastics. J Mater Sci1994; 29: 3377–3383.
44.
BucknallCB. Quantitative approaches to particle cavitation, shear yielding, and crazing in rubber‐toughened polymers. J Polym Sci B Polym Phys2007; 45(12): 1399–1409.
45.
YeeAFLiDLiX. The importance of constraint relief caused by rubber cavitation in the toughening of epoxy. J Mater Sci1993; 28: 6392–6398.
46.
DompasDGroeninckxG. Toughening behaviour of rubber-modified thermoplastic polymers involving very small rubber particles: 1. A criterion for internal rubber cavitation. Polymer1994; 35(22): 4743–4749.
47.
ChengCHiltnerABaerE, et al.Cooperative cavitation in rubber-toughened polycarbonate. J Mater Sci1995; 30: 587–595.
48.
SteenbrinkACVan der GiessenE. On cavitation, post-cavitation and yield in amorphous polymer–rubber blends. J Mech Phys Solid1999; 47(4): 843–876.
49.
BagheriRPearsonRA. Role of particle cavitation in rubber-toughened epoxies: II. Inter-particle distance. Polymer2000; 41(1): 269–276.
50.
WuS. A generalized criterion for rubber toughening: the critical matrix ligament thickness. J Appl Polym Sci1988; 35(2): 549–561.
51.
HuangYKinlochAJ. The role of plastic void growth in the fracture of rubber-toughened epoxy polymers. J Mater Sci Lett1992; 11(8): 484–487.
52.
HuangYKinlochAJ. Modelling of the toughening mechanisms in rubber-modified epoxy polymers: part I finite element analysis studies. J Mater Sci1992; 27: 2753–2762.
53.
LazzeriABucknallCB. Dilatational bands in rubber-toughened polymers. J Mater Sci1993; 28: 6799–6808.
54.
GuildFJKinlochAJTaylorAC. Particle cavitation in rubber toughened epoxies: the role of particle size. J Mater Sci2010; 45: 3882–3894.
55.
GibsonRF. Principles of composite material mechanics. CRC Press, 2007.
56.
JiangWLiangHJiangB. Interparticle distance-temperature-strain rate equivalence for the brittle-tough transition in polymer blends. Polymer1998; 39(18): 4437–4442.
57.
NicolaisLNarkisM. Stress‐strain behavior of styrene‐acrylonitrile/glass bead composites in the glassy region. Polym Eng Sci1971; 11(3): 194–199.
58.
YangJZhangYZhangY. Brittle–ductile transition of PP/POE blends in both impact and high speed tensile tests. Polymer2003; 44(17): 5047–5052.
59.
BascomWDTingRYMoultonRJ, et al.The fracture of an epoxy polymer containing elastomeric modifiers. J Mater Sci1981; 16: 2657–2664.
60.
ZhouMRosakisAJRavichandranG. Dynamically propagating shear bands in impact-loaded prenotched plates—I. Experimental investigations of temperature signatures and propagation speed. J Mech Phys Solid1996; 44(6): 981–1006.
GuduruPRRosakisAJRavichandranG. Dynamic shear bands: an investigation using high speed optical and infrared diagnostics. Mech Mater2001; 33(7): 371–402.
