Study of mechanical properties of epoxy/graphene and epoxy/halloysite nanocomposites

Resea ch A icle Lubomí Lapčík*, Ha un Sepe cioğlu, Youse Mu aja, Ba bo a Lapčíko á, Ma in Vašina, Ma in O sík, Michal S aněk, and Shwe a Gau am S udy o mechanical p ope ies o epoxy/ g aphene and epoxy/halloysi e nanocomposi es h ps://doi.o g/10.1515/n e -2022-0520 ecei ed Oc obe 3, 2022; accep ed Feb ua y 3, 2023 Abs ac : This a icle aimed o compa e a ious mechan- ical p ope ies o epoxy/g aphene and epoxy/halloysi e nanocomposi es. G aphene nanopla ele s (GnPs)and hal- loysi e nano ubes (HNTs)we e used as fille s a diffe en concen a ions. The s udied fille s we e dispe sed in he epoxy esin ma ices. Elas ic–plas ic mechanical beha io modula ion was obse ed u ilizing he fille s’nanopa i- cles and ca boxyl- e mina ed bu adiene–ac yloni ile copolyme ubbe -modified epoxy esin. The hypo hesis o he possible p eceding in e -pa icle gliding o he indi- idual GnPs in he complex esin nanocomposi e ma ix du ing mechanical es ings was also confi med. Inc eased duc ili y (elonga ion a b eak inc eased om 0.33 mm [nea ma ix] o 0.46 mm [1 w % GnPs][39% inc ease]) and plas ici y o he GnP nanocomposi e samples we e obse ed. In con as , he dec easing mechanical s iffness as eflec ed in he dec eased Young’s modulus o elas ici y ( om 3.4 o 2.7 GPa [20% dec ease]) was ound o he epoxy/HNT nanocomposi es. The ob ained dynamic s iff- ness o he in es iga ed nanocomposi es confi med he complexi y o he mechanical esponse o he s udied ma e ial sys ems as a combina ion o he duc ile and b i le phenomena. Keywo ds: g aphene, halloysi e, nanocomposi es, epoxy polyme , CTBN ubbe , mechanical es ing 1 In oduc ion Polyme ic and esin-based nanocomposi es a e widely used in ma e ial enginee ing esea ch owing o hei capaci y o modula e plas ic–elas ic mechanical pe o - mance a s a ic and dynamic mechanical loadings [1]. These nanocomposi es a e cha ac e ized by high mechan- ical oughness and wea esis ance, imp o ed sel -lub ica- ion p ope ies, and low ic ion coefficien [2,3]. The e o e, hey ha e a wide ange o applica ion po en ial in he ae ospace [4], au omo i e [5], chemical, and elec onic indus ies as well as high- ol age ou doo insula ion ma e- ials [6–8]. The abili y o a ma e ial o abso b mechanical impac , i.e., i s oughness, equi es high o ce esis ance and he exis ence o he de o ma ion mechanisms ha abso b and dissipa e he applied mechanical ene gy o e a la ge pa h, in a la ge olume, and o a sufficien ly long ime. Such mechanisms may be inhe en in he ma e ial due o i s specific mic os uc u e bu can also be delibe a ely inco - po a ed in o he s uc u e o polyme /epoxy esin compo- si es and blends [9,10]. Such syne gis ic effec can be ob ained by p ope selec ion o he combina ion o he nanofille pa icles’ ype (g aphene nanopla ele s [GnPs], halloysi e nano ubes [HNTs],e c.),shape,andsu ace chemis y, by modula ing he physicochemical cha ac e is ics o he ma ix, e c., o example, by adding ubbe y plas ic componen s [11,12]. Howe e , li e a u e indica es ha ela- i ely ew s udies ha e ocused on ca boxyl- e mina ed bu a- diene–ac yloni ile (CTBN)copolyme ubbe -modified epoxy  * Co esponding au ho : Lubomí Lapčík, Depa men o Physical Chemis y, Facul y o Science, Palacky Uni e si y, 17. Lis opadu 12, 771 46 Olomouc, Czech Republic; Facul y o Technology, Tomas Ba a Uni e si y in Zlin, Nam. T.G. Masa yka 275, 760 01 Zlin, Czech Republic, e-mail: [email p o ec ed] Ha un Sepe cioğlu: Depa men o Me allu gy and Mechanical Enginee ing, Technology Facul y, Selçuk Uni e si y, Konya 42075, Tu key Youse Mu aja: Depa men o Physical Chemis y, Facul y o Science, Palacky Uni e si y, 17. Lis opadu 12, 771 46 Olomouc, Czech Republic Ba bo a Lapčíko á: Depa men o Physical Chemis y, Facul y o Science, Palacky Uni e si y, 17. Lis opadu 12, 771 46 Olomouc, Czech Republic; Facul y o Technology, Tomas Ba a Uni e si y in Zlin, Nam. T.G. Masa yka 275, 760 01 Zlin, Czech Republic Ma in Vašina: Facul y o Technology, Tomas Ba a Uni e si y in Zlin, Nam. T.G. Masa yka 275, 760 01 Zlin, Czech Republic; Depa men o Hyd omechanics and Hyd aulic Equipmen , Facul y o Mechanical Enginee ing, VŠB-Technical Uni e si y o Os a a, 17. Lis opadu 15/2172, 708 33 Os a a-Po uba, Czech Republic Ma in O sík, Michal S aněk, Shwe a Gau am: Facul y o Technology, Tomas Ba a Uni e si y in Zlin, Nam. T.G. Masa yka 275, 760 01 Zlin, Czech Republic Nano echnology Re iews 2023; 12: 20220520 Open Access. © 2023 he au ho (s), published by De G uy e . This wo k is licensed unde he C ea i e Commons A ibu ion 4.0 In e na ional License. esins filled wi h GnPs exhibi ing he imp o ed ac u e oughness [13–16]. Se e al polyme composi es ha e been epo ed in ecen yea s, including polyes e , polyu e hane, epoxy, and phenolics [17,18]. Among hese, epoxy polyme com- posi es ha e gained emendous a en ion due o hei high mechanical oughness and mois u e abso p ion p op- e ies [19]. Addi ionally, hese esins show less sh inkage and less oxic emissions du ing he cu ing p ocess [20]. The e o e, epoxy esins a e conside ed high-quali y ma e- ials on an indus ial scale, despi e hei high cos [21]. In gene al, he plas ic o iscoelas ic de o ma ion o ma e ials in on o he c ack apex emo es pa o he c ack ene gy and hus con ols i s p og ess wi hin he ma ix. The e o e, he diffe ence be ween b i le and duc- ile ac u es is in hei spa ial localiza ion and hei em- po al p og ession. Mos polyme composi e ma e ials can b eak down by ei he b i le o duc ile ac u es depending on he ex e nal condi ions o p ocesses aking place in he ma e ial. The ansi ion be ween duc ile and b i le ac- u es can be empe a u e dependen , wi h he empe a u e egions o he wo dis inc mechanisms sepa a ed by he emb i lemen empe a u e. The la e always lies below he glass- ansi ion empe a u e. In he same sense, wi h a d op in empe a u e, an inc ease in loading a e can ha e an effec –al hough he diffe ence in loading a e mus be an o de o magni ude g ea e o ha e an effec on he na u e o he ac u e. Howe e , long- e m s a ic loading below he yield s ess o many polyme s also leads o b i le ac u e. In his case, he “ma e ial sel -de ence” mechanisms canno de elop sufficien ly by c ea ing a plas ic zone in on o he c ack ip [9]. T ibological p ope ies o esins o en indi ec ly influ- ence hei mechanical s eng h, whe eas epoxy esins exhibi limi ed ibological p ope ies [22]. Fo example, he se ice li e o pipes made o polyme ic composi es depends on he effec i i y o he ene gy dissipa ion du ing fluid flow, he cha ac e o which is dependen on he wall ic ion o he anspo ed medium. Such pipes a e exposed unde se ice condi ions o long- e m s esses, usually unde ela i ely low empe a u es, bu some- imes also a he in e ac ion o an ac i e en i onmen . Unde hese condi ions, hey canno p ope ly de elop he “sel -de ense”mechanisms o c ack blun ing by local plas ic de o ma ion, and om he exposed su ace small c acks p opaga e inside he ma e ial o e en sha p c acks, which e en ually lead o b i le ac u e [9]. Se e al me hods ha e been epo ed o imp o e hese p ope ies, i.e., adding mic o-and nano-sized pa icles as fille s in he esin ma ix [23,24]. A la ge a ie y o nano- fille s, such as SiO 2 , MnO 2 , TiO 2 ,Al 2 O 3 , SiC, Si 3 N 4 , ZnO, MoS 2 , nanoclay, and ca bon nano ubes, ha e been epo ed in diffe en ypes o polyme ic esins [25–28].Thesefille s ha e demons a ed a ying efficiencies wi h ce ain limi a- ions, which hinde hei p ac ical applica ions [29]. GnPs, consis ing o 30–40 laye s o g aphene, a e widely used nanoma e ials due o hei high he mal s a- bili y and conduc i i y, high Young’s modulus o elas i- ci y, high op ical ansmi ance, high ac u e s eng h, and imp o ed lub ica ion p ope ies [17,30]. Due o hei inhe en , in insic ene gy-dissipa ing mechanisms (shee bending and sliding), GnPs belong o highly ad anced ma e ials used in composi e manu ac u ing [17,31]. How- e e , i is necessa y o op imize he con en o g aphene nanofille s in epoxy esins because highe con en leads o nonuni o m dis ibu ion o g aphene in he polyme ne wo k [32]. Ano he challenge is he obse ed high agg ega ion a es o g aphene a ising om he ac ing Van de Waals in e ac ion o ces [33–35]. Fo his eason, i is necessa y o op imize a p ope mass a io o g a- phene nanofille s o epoxy esin in o de o ob ain he desi ed mechanical p ope ies. Halloysi e, an aluminosilica e clay ma e ial [36],is ano he fille commonly used in polyme esins owing o i s cylind ical s uc u e, imp o ed mechanical pe o - mance, and low cos [37,38]. HNTs exhibi highe dispe - sion a io and ha e su ace hyd oxyl g oups wi h low densi y, which esul s in hei smoo h diffusion in o he polyme ma ix, leading o less agg ega ion [39]. Mo e- o e , due o small basal spacing o c ys al planes, he in e cala ion o HNTs wi h polyme s and addi i es is di - ficul [40,41]. Howe e , HNT nanofille s belong o po en- ial unc ional fille s used in indus ial p ac ice [42,43]. Published esul s confi med syne gis ic combina ion o he plas ifica ion effec o he igid epoxy ma ix assigned o he gliding o he indi idual GnP nanofille s and he s iffening effec o he HNT nanofille s when ac u e ough- ness inc eased. The la e plas ifica ion was also enhanced by he addi ion o he CTBN polyme ic ubbe componen o he composi e epoxy ma ix, hus imp o ing ma e ial’s ac- u e oughness. A simila effec was also confi med by mole- cula dynamics simula ions o mono helical so segmen s based on New onian mechanics heo y [44]. In his s udy, GnPs and HNTs we e used sepa a ely as fille s o imp o e he mechanical pe o mance, dispe - sion, he mal s abili y, and op o-elec onic p ope ies o he epoxy esin composi e. A a ying mass a io o bo h fille s was used in p epa ed composi es, and he effec o he applied nanofille s was e alua ed by uniaxial ensile es ing, ac u e oughness measu emen s, uniaxial bending es ing, inden a ion mic o-ha dness measu emen s, and nondes uc i e ib a ion es ing. 2Lubomí Lapčík e al. 2 Ma e ials 2.1 Ma e ials The esin and ha dene used in his s udy we e diglycidyl e he o bisphenol A esin (DGEBA)wi h low iscosi y ( ade name: lamina ing esin MGS L285)(Figu e 1a)and 3-aminome hyl-3,5,5 ime hylcyclohexylamine ( ade name: L285), espec i ely (bo h ma e ials we e p o ided om Hexion, USA)(Figu e 1b). The liquid ubbe used was CTBN copolyme (pu chased om Zibo Qilong, China)wi h an a e age o 0.58–0.65 ca boxyl g oups pe molecule; i s numbe a e age molecula weigh was abou 3,800 Da, and he con en o ac yloni ile was o 8–12% (Figu e 1c). The echnical da a o he CTBN a e gi en in Table 1. The chemical s uc u es o epoxy, ha dene , and CTBN a e showninFigu e1.Nanofille s used in his s udy we e non- unc ionalized plana -shaped GnPs o 800 m 2 /g specific su ace a ea, laye hickness o 3–7nmwi hana e age laye wid h o 1.5 μm, and 99.9% pu i y (pu chased om Nanog afi,Anka a,Tu key).TheHNTs(Al 2 Si 2 O 5 (OH) 4 )used had wo laye s o nanocylind ical s uc u e (Esan Eczacıbası (Is anbul, Tu key)), whose inne diame e , ou e diame e , and leng h we e in he ange o 1–20, 30–50, and 100–800 nm, espec i ely. 2.2 P epa a ion o nanocomposi es and epoxy blends 2.2.1 CTBN–epoxy blends The chemical o mulas o he used epoxy blends a e shown in Figu e 1. Fo p epa ing he epoxy blends wi h CTBN liquid ubbe , 10 w % CTBN was mechanically mixed wi h epoxy esin in a glass beake placed on a p ehea ed pla e. The blends in he beake we e hen s i ed by ul asonica ion o 15–20 min o ob ain homo- geneous blends, ollowed by 1 h o degassing in he acuum o en a 60°C. The amine-based cu ing agen was subsequen ly added a a s oichiome ic a io o 80:20 (epoxy:ha dene )by weigh a slow s i ing. Blends we e subsequen ly cas in o molds and cu ed o 1 h a 90°C, ollowed by 3 h pos -cu ing a 120°C. 2.2.2 CTBN–GnPs–epoxy and CTBN–halloysi e–epoxy composi es The nano- ein o cemen a ios o he epoxy mix u es we e c ea ed based on he li e a u e. Many au ho s [43,45–49] ha e expe imen ally s udied he concen a ion o GnP and HNTs in he epoxy ma ix o be in he ange o (0–1)and (0–5)w %, espec i ely, and epo ed he effec o hese concen a ions on ensile, ac u e, and flexu al p ope ies o he nea ma ix. Fo p epa ing he epoxy mix u es wi h GnPs and HNTs (see Figu e 2 o scanning elec on mic o- scopy [SEM]), 0, 0.125, 0.25, 0.5, 0.75, and 1 w % GnPs and 0, 1, 2, 3, 4, and 5 w % HNTs we e added o he epoxy esin, and he ob ained mix u es we e ans e ed in o a RETSCH-PM 100 plane a y mill o mixing a a o a ion a e o 200 pm o 25 h. The epoxy composi e mix u es we e p epa ed using 10 mm diame e balls and a bowl made o ungs en ca bide as mixing media. The mixing bowls we e loaded wi h he epoxy mix u es and balls, esul ing in a ball- o-powde mass a io o 30:1. Fi s , he mix u es we e mixed o 30 min, hen es ed o 10 min o a oid o e - hea ing, hen mixed again, and he cycle was con inued un il he decided mixing ime was comple ed. Subse- quen ly, 10 w % CTBN was added o each epoxy mix u e con aining he GnP and HNT ein o cemen s o p epa ing he CTBN–GnPs–epoxy and CTBN–HNTs–epoxy compo- si es. The p epa ed mix u es we e s i ed using ul asoni- ca ion o 25–30 min o ob ain he homogeneous mix u es, ollowed by degassing in a acuum o en a 60°C o abou 1 h. Finally, he cu ing p ocedu e o CTBN–epoxy blends Figu e 1: The chemical s uc u e o componen s (a)DGEBA, (b)3- aminome hyl-3,5,5- ime hylcyclohexylamine, and (c)CTBN. Table 1: P ope ies o he applied CTBN liquid ubbe Pa ame e Value Viscosi y (40°C)(Pa s)7−12 Ca boxyl con en (mmol/g)0.58−0.65 Ni ile g oup con en (%)8.0−12.0 Wa e con en (%)≤0.05 Vola ile con en (%)≤2.0 G aphene and halloysi e epoxy nanocomposi es 3 desc ibed in Sec ion 2.2.1 was ollowed o cu e he CTBN–GnPs–epoxy and he CTBN–HNTs–epoxy compo- si es. The same CTBN liquid ubbe concen a ion o 10 w % was used in all o he in es iga ed epoxy/g aphene and epoxy/halloysi e nanocomposi es; he i gin epoxy ma ix p epa ed was wi hou CTBN liquid ubbe . 3 Me hods 3.1 SEM analysis Zeiss E oLS10 equipped wi h an ene gy-dispe si e X- ay de ec o (Ge many)was used o SEM analysis. SEM images we e aken by deposi ing nanofille samples on a s anda d 400-g id coppe mesh. Fille s’ace one dispe - sions we e ul asonica ed o 15 min, cas on he coppe mesh, and ai d ied. SEM measu emen s we e pe o med a an accele a ing ol age o 2 kV. 3.2 Uniaxial ensile es ing Uni e sal Tes ing Machine Au og aph AGS-100 Shimadzu (Japan)and Zwick 1456 mul ipu pose es e (Zwick Roell, Ulm, Ge many)equipped wi h Compac The mos a ic Chambe TCE Se ies we e used o ensile es ing o injec ion-molded specimens. All da a we e eco ded as pe ČSN EN ISO 527-1 and ČSN EN ISO 527-2 s anda ds o he es ed gauge leng h o 80 mm. All expe imen s we e pe o med a oom empe a u e up o b eak wi h a 50 mm/min de o - ma ion a e. Young’s modulus o elas ici y and elonga ion a b eak we e ob ained om he s ess–s ain dependency plo s. Each expe imen was epea ed 10×,andmean alues and s anda d de ia ions o he measu ed quan- i ies we e subsequen ly calcula ed. All expe imen s we e pe o med a he ambien labo a o y empe a u e o 25°C. 3.3 Cha py impac es ing Impac es s we e ca ied ou using Zwick 513 Pendulum Impac Tes e (Zwick Roell, Ulm, Ge many)acco ding o he ČSN EN ISO 179-2 s anda d, allowing a 25 J ene gy d op. Each expe imen was epea ed 10×and mean alues and s anda d de ia ions o he ac u e oughness we e calcula ed. All expe imen s we e pe o med a he ambien labo a o y empe a u e o 25°C. 3.4 Mic o-ha dness Mic o-inden a ion es s we e pe o med on a mic o-inden- a ion es e (Mic o Combi Tes e , An on Paa , Aus ia), acco ding o he ČSN EN ISO 14577 s anda d. The applied diamond ip was cube-co ne shaped (Vicke s, An on Paa , Aus ia). Measu emen pa ame e s we e se as ol- lows: he maximum load o 3 N, loading a e (unloading a e)o 6 N/min, and holding ime o 90 s. All expe imen s we e pe o med acco ding o he dep h-sensing inden a- ion me hod, allowing simul aneous measu emen o he ac ing o ce on he inden e and he displacemen o he inden e ’s ip. The inden a ion modulus (E IT )was calcula ed om he plane s ain modulus o elas ici y (E*)using an es ima ed Poisson’s a io(ν)o he samples (0.3–0.4 [50,51]): ()=*−EE ν1 . IT 2(1) Each measu emen was epea ed 10×, and mean alues and s anda d de ia ions o he inden a ion modulus we e calcula ed. All expe imen s we e pe o med a he ambien labo a o y empe a u e o 25°C. Figu e 2: SEM images o he s udied fille s: (a)GnPs, (b)HNT. 4Lubomí Lapčík e al. 3.5 Uniaxial h ee-poin bending es s The uniaxial h ee-poin bending es was ca ied ou on a Zwick 1456 es ing machine (Zwick Roell GmbH &Co. KG, Ulm, Ge many)acco ding o he ČSN EN ISO 14125 s anda d. The esul s we e e alua ed using he Tes Xpe so wa e. The dis ance be ween he suppo s was se o 64 mm, and he oundness o he suppo s and he load mand el was 5 mm. The de o ma ion a e du ing he h ee-poin bending es was 1 mm/min, and he loading eloci y was 50 mm/min. 3.6 Displacemen ansmissibili y measu emen s Displacemen ansmissibili y T d is exp essed by he ol- lowing equa ion [52]: ==Ty ya a , d2 1 2 1(2) whe e y 1 is he displacemen ampli ude on he inpu side o he es ed sample, y 2 is he displacemen ampli ude on he ou pu side o he es ed sample, a 1 is he accele a ion ampli ude on he inpu side o he es ed sample, and a 2 is he accele a ion ampli ude on he ou pu side o he es ed sample. The displacemen ansmissibili y o a sp ing–mass–dampe sys em, which is desc ibed by sp ing (s iffness k),dampe (damping coefficien c),andmassm,is gi en by he ollowing equa ion [53]: () ()() () ()() =+ −+ =+· −+· Tkcω kmω cω ∙ ∙∙ 12∙ζ∙ 12∙ζ∙ . d 22 22 2 2 22 2 (3) Unde he condi ion dT d /d =0 in equa ion (3), i is pos- sible o ob ain he equency a io 0 a which he displace- men ansmissibili y eaches i s maximum alue [54,55]: =+− 18∙ζ 1 2∙ζ . 0 2 (4) I is e iden om equa ion (4) ha he local ex eme o he displacemen ansmissibili y is gene ally shi ed o lowe alues o he equency a io wi h inc easing damping a io ζ(o wi h dec easing ma e ial mechanical s iffness k). The local ex ema (i.e., he maximum alue o he displacemen ansmissibili y T dmax )is ound a he equency a io 0 om equa ion (4). The mechanical ib a ion es s we e pe o med by o ced oscilla ion me hod. The displacemen ansmissibili y T d was expe imen ally measu ed using he BK 4810 ib a o in combina ion wi h aBK3560-B-030 signal pulse mul i-analyze and a BK 2706 powe amplifie a he equency ange om 2 o 3,200 Hz. The accele a ion ampli udes a 1 and a 2 on he inpu and ou pu sides o he in es iga ed samples we e eco ded by BK 4393 accele ome e s (B üel & Kjæ , Næ um, Denma k). Measu emen s o he displacemen ansmissibili y we e done o h ee diffe en ine ial masses m( o 0, 90, and 500 g), which we e placed on he op side o he es ed samples. The dimensions o he es ed specimen we e 60 mm ×60 mm ×3mm(leng h ×wid h × hickness). Each measu emen was epea ed 5×a an ambien empe a- u e o 22°C. 4 Resul s and discussion A ypical shape o he used nanofille s, as obse ed by SEM analysis, is shown in Figu e 2. He e he GnP lamella s uc u e was clea ly isible in Figu e 2a wi h a laye hickness o abou 3–7 nm and an a e age laye wid h o 1.5–2.0 μm. In con as , he HNT nano ubes exhibi ed a compac coagula ed s uc u e composed o indi idual nano ubes o app oxima ely 30–50 nm diame e and 100–800 nm leng h (Figu e 2b). Resul s o he ensile- es ing expe imen s o he s u- died nanocomposi es a e shown in Figu e 3. The e was a dec ease o he Young’s modulus o elas ici y (E)du ing uniaxial es ing om 3.4 GPa (nea ma ix) o 2.7 GPa ( o 1 w % epoxy/GnP nanocomposi e)wi h inc easing GnP fille concen a ion [56]. This effec was accompanied by he inc easing nonlinea end o he ob ained magni- udes o he elonga ion a b eak, indica ing inc easing duc ili y and plas icizing effec o he GnP nanofille on he mechanical beha io o he p epa ed epoxy/GnP nano- composi es. Based on he li e a u e [11], i was assumed ha his beha io was asc ibed o he gliding o he indi- idual nanopla ele shee s wi hin complex epoxy/GnP nanocomposi e ma ix accompanied by he c ack deflec- ion, laye b eakage, and sepa a ion/delamina ion o GnP laye s [13]. Howe e , he opposi e effec was ound in he case o he epoxy/HNT nanocomposi es, whe e he Edec eased om 3.4 GPa (nea ma ix) o 2.7 GPa ( o 5 w % epoxy/HNT nanocomposi e), hus indica ing he dec easing mechanical s iffness o he s udied ma e ials. Simul aneously, in con as o he epoxy/GnP nanocomposi es, a mo e b i le beha io wi h inc easing HNT fille concen a ion was obse ed. These obse a ions we e demons a ed by cons an elonga ion a b eak (abou 0.36 mm)dependency as shown in Figu e 3. G aphene and halloysi e epoxy nanocomposi es 5 Based on he a o emen ioned ac s, i was assumed ha he HNT nanofille inc eased he b i leness o he composi e due o he limi ed mo emen o he s iffened HNT nano ubes esul ing in he hinde ed gliding o he HNT nanofille s wi hin he composi e ma ix. The abo e-men ioned esul s o he uniaxial ensile es s we e in excellen ag eemen wi h he obse ed ac- u e oughness measu emen s (Figu e 4), whe e highe ac u e oughness o 8.2 kJ/m 2 o epoxy/HNT nanocom- posi es was ound compa ed o he 6.0 kJ/m 2 o epoxy/ GnP nanocomposi es (bo h a 1 w % fille concen a ion). A highe HNT fille concen a ions (in he concen a ion ange o 1–5w%)nonlinea dec easing end o ac u e oughness was obse ed (Figu e 4). In addi ion, he p esence o CTBN (Figu e 1c)ac ed on he con inuous composi e ma ix as a kind o accel- e a o , which o ces i o de elop local de o ma ions. The de o ma ion mechanisms in he ma ix hen dissipa e he ex e nal mechanical ene gy o e a la ge olume, hus p e en ing he de elopmen o a single b i le c ack. Op imal pe o mance o ubbe modifica ion equi es se - e al condi ions o be me , namely he es ablishmen o a wo-phase mo phology, he p o ision o sa is ac o y in e acial adhesion, and he es ablishmen o a ce ain c i ical dis ance be ween adjacen ubbe domains [9]. Analogous beha io was obse ed o mul i-phase ha d and so segmen al flexible polyme s, whe e ha d phases se ed as s iffening elemen and he so phases p o ided elas ici y [44]. Resul s o he mic o-ha dness s fille concen a ion measu emen s o bo h he s udied epoxy nanocomposi es a e shown in Figu e 5. A nonlinea dec easing end o he inden a ion modulus E IT wi h inc easing fille con- cen a ion was obse ed. In he case o he epoxy/GnP nanocomposi es, E IT dec eased om 4.3 GPa (nea ma ix) o 3.4 GPa ( o 1 w % GnP nanocomposi e). Simila ly, in he case o he epoxy/HNT nanocomposi es, E IT dec eased om 4.3 GPa (nea ma ix) o 3.8 GPa ( o 5 w % HNT Figu e 3: Nanofille concen a ion dependencies o he Young’s modulus o elas ici y and he elonga ion a b eak o he s udied GnPs and HNT nanocomposi es. Applied de o ma ion a e was o 50 mm/min. Con inuous line –Young’s modulus o elas ici y, dashed line – elonga ion a b eak. Figu e 4: Nanofille concen a ion dependencies o he unno ched ac u e oughness o he s udied GnPs and HNT nanocomposi es. 6Lubomí Lapčík e al. nanocomposi e). The plas icizing effec o he applied nanofille s was assumed as he mos p obable cause o his dec ease o su ace ha dness. Resul s o he uniaxial h ee-poin bending es s o he s udied nanocomposi es a e shown in Figu e 6. He e, nonlinea dec easing pa e ns we e ound o bo h he s udied nanocomposi es. Such beha io is ypical o b i le ma e ials. A nonlinea dec ease o he bending modulus (E B ) om 4.3 GPa (nea ma ix) o 2.8 GPa ( o 1 w % GnP nanocomposi e)wi h inc easing GnP fille concen a ion was ound. This effec was accompanied by he inc easing g adual nonlinea end o he ob ained magni udes o he elonga ion a b eak ( om 5.0 mm [nea ma ix]) o 6.0 mm ( o 1 w % epoxy/GnP nanocompo- si e), indica ing inc easing composi e duc ili y due o he plas icizing effec o he nanofille o he p epa ed epoxy/GnP nanocomposi es. In he case o he epoxy/ HNT nanocomposi es, E B nonlinea ly dec eased om 4.3 GPa (nea ma ix) o 3.0 GPa ( o 5 w % epoxy/HNT nanocompo- si es), indica ing dec easing mechanical s iffness o he s udied ma e ials. Howe e , he opposi e, a mino dec easing non- linea end o he elonga ion a b eak s HNT fille concen a- ion, was ound, whe e he elonga ion a b eak dec eased om 5.0 mm (nea ma ix) o 4.1 mm ( o 5 w % epoxy/HNT nano- composi es). These esul s indica ed highe b i leness o he epoxy/HNT nanocomposi es compa ed o he epoxy/ GnP nanocomposi es. Resul s o he dynamic mechanical es s o he s u- died nanocomposi es a e shown in Figu es 7 and 8. Typical equency dependencies o displacemen ans- missibili y a e depic ed in Figu e 7. The ob ained esul s we e in excellen ag eemen wi h he uniaxial ensile measu emen s, indica ing inc eased ma e ial s iffness based on he R1 peak posi ion shi o he highe exci a ion e- quencies acco ding o equa ion (4). Howe e , a mino dec ease o he la e s iffness was ound o low fille concen a ions, as indica ed by he negligible shi o he R1 o he lowe magni udes (Figu e 7a and b). The effec o he ine ial mass magni udes on he equency dependen- cies o he displacemen ansmissibili y is demons a ed Figu e 5: Nanofille concen a ion dependencies o he inden a ion modulus o he s udied GnPs and HNT nanocomposi es. Figu e 6: Nanofille concen a ion dependencies o he bending modulus and he elonga ion a b eak o he s udied GnPs and HNT nanocomposi es. Applied de o ma ion a e was o 50 mm/min. Con inuous line –bending modulus, dashed line –elonga ion a b eak. G aphene and halloysi e epoxy nanocomposi es 7 in Figu e 7c and d. I was ound ha he inc easing ine ial mass led o he dec ease o he fi s esonance equency peak posi ion, he eby esul ing in he imp o ed ma e ials’ mechanical ib a ion-damping p ope ies [53].Inaddi- ion, he ob ained inc easing R1 wi h GnP concen a ion again confi med ma e ials’inc easing s iffness, simila o he case o he p e ious ensile and ac u e oughness measu emen s (Figu es 3 and 4). The la e findings fi e y well wi h he epoxy/GnP nanocomposi e esul s shown in Figu e 8, whe e he linea inc ease o he R1 wi h he fille concen a ion was obse ed. In con as , ob ained esul s o he epoxy/HNT nanocomposi es exhibi ed dec eased Figu e 7: F equency dependencies o he displacemen ansmissibili y o he es ed GnPs and HNT nanocomposi es (Inse in a and b: nanofille s concen a ions)wi h applied ine ial mass o 90 g (inse in c and d: applied ine ial masses). Figu e 8: Concen a ion dependencies o he fi s esonance equencies o he s udied GnPs and HNT nanocomposi es. Inse legend: ine ial mass used. 8Lubomí Lapčík e al. mechanical s iffness as indica ed by dec easing R1 wi h inc easing fille concen a ion o he applied ine ial masses. 5 Conclusions The possibili y o elas ic–plas ic mechanical beha io mod- ula ion by means o he applica ion o nanosized GnPs and HNT fille s in he complex epoxy esin-based nanocompo- si es was confi med in his s udy. A complex nonlinea pa - e n o Young’s modulus o elas ici y wi h inc easing GnP fille concen a ion was ound. Simul aneously, in he con- cen a ion ange o 0–1w %GnPnanofille concen a ion, an inc easing duc ili y o he s udied nanocomposi es was ound, as eflec ed in he samples’inc eased elonga ion a b eak. This kind o beha io was in e p e ed by he in e - pa icle gliding effec o he indi idual GnP nanopa icles dispe sed in he complex epoxy esin ma ix. A ela i ely cons an end o Young’s modulus o elas ici y (app oxi- ma ely o abou 2.8 GPa)accompanied by he simila non- linea pa e n o elonga ion a b eak (app oxima ely o 0.35 mm) o he s udied epoxy/HNT nanocomposi es in he concen a ion ange o 1–5w %wasalso ound.I was a ibu ed o he hinde ed local mo emen o he HNT nanofille s in he ma ix du ing mechanical es s. F ac u e mechanical es s confi med ha he ac u e oughness ob ained a low fille concen a ions was highe in he case o he s iffepoxy/HNT nanocomposi es compa ed o he epoxy/GnP nanocomposi es due o he GnP fille ’s gliding-dissipa i e effec . As ob ained by he uniaxial h ee-poin bending es s, he elonga ion a b eak mea- su emen s confi med he enhanced plas ici y and duc i- li y wi h inc easing GnP fille concen a ion o he com- plex epoxy/GnP nanocomposi es. This was eflec ed in he exceeding magni ude o he elonga ion a b eak o 6 mm compa ed o 5.3 mm o he epoxy/HNT nanocom- posi es (bo h a 1 w % nanofille concen a ion). A simila effec was also confi med by mic o-ha dness es s, whe e he obse ed inden a ion modulus o 3.4 GPa o epoxy/ GnP nanocomposi es was lowe compa ed o 4.0 GPa o epoxy/HNT nanocomposi es (bo h a 1 w % nanofille con- cen a ion), hus indica ing mo e dissipa i e mechanical beha io o he epoxy/GnP nanocomposi es. The la e we asc ibed o he abo e-men ioned GnP nanofille gliding ic ion. As a no el app oach, he nondes uc i e mechan- ical ib a ion damping me hod o o ced oscilla ions was applied in he low- equency egion o 2–3,200 Hz o he compa ison o mechanical p ope ies based on he fi s esonance equency peak posi ion. The plas ifica ion effec o he epoxy/GnP nanocomposi es was confi med by he lowe magni ude o he fi s esonance equency peak posi ion o 2.6 kHz compa ed o he obse ed magni ude o he R1 o 2.8 kHz o epoxy/HNT nanocomposi es (bo h esul s ob ained a 1 w % nanofille concen a ion and ze o ine ial mass). Funding in o ma ion: This s udy was suppo ed by he Eu opean Regional De elopmen Fund in he Resea ch Cen e o Ad anced Mecha onic Sys ems p ojec , p ojec numbe CZ.02.1.01/0.0/0.0/16_019/0000867. LL and YM would like o exp ess hei g a i ude o financing his esea ch by he in e nal g an s o Palacky Uni e si y in Olomouc IGA_P F_2022_020, IGA_P F_2023_024 and o Tomas Ba a Uni e si y in Zlin (p ojec nos IGA/FT/2022/005 and IGA/FT/2023/007). Financial suppo o YM by Fische schola ship o he Facul y o Science, Palacky Uni e si y in Olomouc, in he yea 2022/2023, is also g a e ully acknowledged. Au ho con ibu ions: All au ho s ha e accep ed espon- sibili y o he en i e con en o his manusc ip and app o ed i s submission. Conflic o in e es : The au ho s s a e no conflic o in e es . Re e ences [1]Lapcik L, Jind o a P, Lapciko a B, Tamblyn R, G eenwood R, Rowson N. Effec o he alc fille con en on he mechanical p ope ies o polyp opylene composi es. J Appl Polym Sci. 2008 Dec 5;110(5):2742–7. [2]Bheemappa S, Gu umu hy H. Recen ad ances in ab ica ion and cha ac e iza ion o nanofille filled epoxy nanocompo- si es. T ends Fab Polym Polym Compos. 2022;2022:1–40. [3]Ogbonna VE, Popoola A, Popoola OM, Adeosun SO. A e iew on he ecen ad ances on imp o ing he p ope ies o epoxy nanocomposi es o he mal, mechanical, and ibological applica ions: challenges and ecommenda ions. Polym Technol Ma e . 2022;61(2):176–95. [4]K asny I, Lapcik L, Lapciko a B, G eenwood RW, Sa a o a K, Rowson NA. 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