Ci a ion: As ouski, I.; Kudelo a, T.;
Kali oda, J.; Raudensky, M. Shea
S eng h o Adhesi e Bonding o
Plas ics In ended o High
Tempe a u e Plas ic Radia o s.
P ocesses 2022,10, 806.
h ps://doi.o g/10.3390/p 10050806
Academic Edi o : Geo ge Z. Kyzas
Recei ed: 29 Ma ch 2022
Accep ed: 15 Ap il 2022
Published: 20 Ap il 2022
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A ibu ion (CC BY) license (h ps://
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p ocesses
A icle
Shea S eng h o Adhesi e Bonding o Plas ics In ended o
High Tempe a u e Plas ic Radia o s
Ilya As ouski , Te eza Kudelo a * , Jose Kali oda and Mi osla Raudensky
Hea T ans e and Fluid Flow Labo a o y, Facul y o Mechanical Enginee ing, B no Uni e si y o Technology,
Technicka 2896/2, 616 69 B no, Czech Republic; [email p o ec ed] (I.A.); [email p o ec ed] (J.K.);
mi osla [email p o ec ed] (M.R.)
*Co espondence: e [email p o ec ed]
Abs ac :
The use o adhesi e join s has inc eased in ecen decades due o hei compe i i e ea u es
in compa ison wi h o he joining me hods. They can be used in speci ic applica ions whe e he e is
no possibili y o use al e na i e connec ion echniques. Adhesi e bonding was used o assemble he
p o o ype o a high- empe a u e ca adia o (ope a ed up o 125
◦
C) wi h a o al o 12,240 plas ic
ubes. This wo k aims o es ima e he shea s eng h o di e en adhesi es in ended o bonding
he plas ics used o assemble he abo e-men ioned high- empe a u e adia o . Fou een comme cial
adhesi es we e es ed wi h one he mose plas ic (G11 glass ab ic epoxy shee s) and wo glass-
ein o ced he moplas ics (polyamide PA66-GF30 and polyphenylene sul ide PPS-GF40). Tes s we e
conduc ed acco ding EN 1465 o de e mine ensile lap-shea s eng h o bonding. Tes ing showed
ha only 4 o he 14 adhesi es es ed exhibi subs an ial bonding s eng h a empe a u es abo e
120
◦
C and only one is esis an a 180
◦
C. The AS60/AW60 adhesi e showed he bes esul s o all
h ee subs a es: 1.6 MPa o epoxy shee s and PA66-GF, and 1.4 MPa o PPS-GF40. Addi ionally, he
in luence o he su ace ea men wi h cold plasma was e alua ed on a clean and ac i a ed bonding
su ace, causing a 30% inc ease in he shea s eng h.
Keywo ds: plas ics; adhesion; gluing; shea s eng h; ac u e analysis
1. In oduc ion
In ecen decades, enginee ing he moplas ics and ibe -en o ced plas ic composi es
ha e been used mo e and mo e o a a ie y o applica ions, such as au omo i e, ae ospace,
and elec o echnical equipmen . These ma e ials success ully compe e wi h me als (mainly
aluminum alloys) because o hei ligh ness, good mechanical and p ocessing p ope ies,
and hei esis ance o en i onmen al condi ions and co osion. Polyme ic hollow- ibe
hea exchange s a e a new ype o hea exchange which can compe e wi h me al ones in
applica ions whe e low weigh and co osion esis ance a e impo an . Cu en ly, hey a e
being es ed as a hea exchange in many applica ions including au omo i e [
1
,
2
] and Li-ion
ba e y he mal managemen [
3
,
4
]. To achie e high he mal pe o mance, liquid- o-gas
plas ic hea exchange s should be made o a la ge numbe o hollow ibe s o ensu e bo h
low ube wall hickness and high ai -side ans e a ea [
5
]. Figu e 1shows a polyme ic
ibe adia o made o a o al o 12,240 ubes (34 laye s o 360 ubes). Connec ion o such a
numbe o mic o ubes using classical me hods like he moplas ic o e moulding o welding
is e y complica ed o impossible. Tha is he eason al e na i e he mose ma e ials, in
ou case epoxides, should be used. On he o he hand, he epoxides canno be connec ed
by welding (because he e is no mel ing, as he e is o he moplas ics), so he associa ed
connec ion should be made h ough bonding.
Adhesi e bonding c ea es pe manen insepa able join s by applying and solidi ying
he adhesi e laye be ween he pa s. Adhesi e bonding is a e y e ec i e ype o connec-
ion because i is e y simple and has a e y good s eng h o weigh a io. Also, his ype
P ocesses 2022,10, 806. h ps://doi.o g/10.3390/p 10050806 h ps://www.mdpi.com/jou nal/p ocesses
P ocesses 2022,10, 806 2 o 15
o connec ion does no dis o he componen s being joined and does no c ea e s ess. The
bene i s o adhesi e bonding a e e y impo an o au omo i e and ae ospace, whe e he e
is a s ong end o use ligh weigh ma e ials and join s [
6
]. On he o he hand, adhesi e
bonding has se e al limi a ions. One o he main disad an ages is ha he p ope ies o
bonded join s a e a ec ed by a ying empe a u e and en i onmen al condi ions. Also, he
p ope solidi ica ion o some adhesi es equi es hea cu ing and can be a complica ion o
he assembly p ocess. Mo eo e , adhesi e join s a e conside ed inhe en ly weak unde peel
loading [
7
]. The in luence o empe a u e on he bonded connec ion is also associa ed wi h
po en ial di e ences in he he mal expansion o ma e ials and he adhesi e laye because
i c ea es addi ional s ess in he join a ea when he empe a u e a ies [
8
]. Mo eo e , he
majo i y o adhesi es a e polyme -based and show some deg ada ion when exposed o
high empe a u es. The o he main de ining p ope y o adhesi es o high- empe a u e
applica ions is he glass ansi ion empe a u e, Tg. A empe a u es below Tg, he ma e ial
is b i le wi h high modulus and s eng h. Abo e Tg, he ma e ial so ens, and he adhesi e
is mo e elas ic and oughe , bu wi h limi ed mechanical s eng h. The e o e, a high Tg is
s ongly equi ed o high- empe a u e adhesi es [9].
P ocesses 2022, 10, x FOR PEER REVIEW 2 o 16
(a) (b)
Figu e 1. (a) Plas ic hea exchange wi h coolan mani olds made o glass ab ic en o ced epoxy G11
EPGC308, adop ed om [1]; (b) diag am o he bonding connec ion applied o glue he hea
exchange co e o he mani olds.
Adhesi e bonding c ea es pe manen insepa able join s by applying and solidi ying
he adhesi e laye be ween he pa s. Adhesi e bonding is a e y e ec i e ype o
connec ion because i is e y simple and has a e y good s eng h o weigh a io. Also,
his ype o connec ion does no dis o he componen s being joined and does no c ea e
s ess. The bene i s o adhesi e bonding a e e y impo an o au omo i e and ae ospace,
whe e he e is a s ong end o use ligh weigh ma e ials and join s [6]. On he o he hand,
adhesi e bonding has se e al limi a ions. One o he main disad an ages is ha he
p ope ies o bonded join s a e a ec ed by a ying empe a u e and en i onmen al
condi ions. Also, he p ope solidi ica ion o some adhesi es equi es hea cu ing and can
be a complica ion o he assembly p ocess. Mo eo e , adhesi e join s a e conside ed
inhe en ly weak unde peel loading [7]. The in luence o empe a u e on he bonded
connec ion is also associa ed wi h po en ial di e ences in he he mal expansion o
ma e ials and he adhesi e laye because i c ea es addi ional s ess in he join a ea when
he empe a u e a ies [8]. Mo eo e , he majo i y o adhesi es a e polyme -based and
show some deg ada ion when exposed o high empe a u es. The o he main de ining
p ope y o adhesi es o high- empe a u e applica ions is he glass ansi ion
empe a u e, Tg. A empe a u es below Tg, he ma e ial is b i le wi h high modulus and
s eng h. Abo e Tg, he ma e ial so ens, and he adhesi e is mo e elas ic and oughe , bu
wi h limi ed mechanical s eng h. The e o e, a high Tg is s ongly equi ed o high-
empe a u e adhesi es [9].
Bonding join s can ail adhesi ely o cohesi ely. Adhesi e ailu e is in e acial ailu e
on he su ace be ween he adhesi e and he subs a e. Cohesi e ailu e occu s when a
ac u e is inside o he adhesi e laye allowing adhesi e o emain on bo h pa s o he
subs a e. In some cases, he subs a e ails p io o he adhesi e, and i is known as a
cohesi e ailu e o he subs a e. Figu e 2 shows he ailu e pa e ns o adhesi e and
cohesi e join ailu es due o EN ISO 10365: 1992 [10]. In analyzing an adhesi e join ha
has been des uc ion es ed, he mode o ailu e is o en exp essed as a pe cen age o
cohesi e o adhesi e ailu es.
Figu e 1.
(
a
) Plas ic hea exchange wi h coolan mani olds made o glass ab ic en o ced epoxy
G11 EPGC308, adop ed om [
1
]; (
b
) diag am o he bonding connec ion applied o glue he hea
exchange co e o he mani olds.
Bonding join s can ail adhesi ely o cohesi ely. Adhesi e ailu e is in e acial ailu e
on he su ace be ween he adhesi e and he subs a e. Cohesi e ailu e occu s when
a ac u e is inside o he adhesi e laye allowing adhesi e o emain on bo h pa s o
he subs a e. In some cases, he subs a e ails p io o he adhesi e, and i is known as
a cohesi e ailu e o he subs a e. Figu e 2shows he ailu e pa e ns o adhesi e and
cohesi e join ailu es due o EN ISO 10365:1992 [
10
]. In analyzing an adhesi e join ha has
been des uc ion es ed, he mode o ailu e is o en exp essed as a pe cen age o cohesi e
o adhesi e ailu es.
P ocesses 2022,10, 806 3 o 15
P ocesses 2022, 10, x FOR PEER REVIEW 3 o 16
Figu e 2.Adhesi e and cohesi e join ailu es acc. o EN ISO 10365:1992. (The igu e was modi ied
acco ding o [10]).
On he one hand, cohesi e ailu e wi hin he adhesi e o in he subs a e is he
p e e ed ype o ailu e because wi h his ype, he maximum s eng h o he ma e ials in
he join has been eached. On he o he hand, he cohesi e ailu e ound by an ele a ed
empe a u e es may indica e ha he adhesi e los i s s eng h and is no sui able o his
empe a u e.
Vice e sa, adhesi e ailu e means ha he adhesi e inne s eng h is highe han he
o ces be ween he adhesi e and he subs a e. The e a e se e al di e en mechanisms o
he adhesion, bu he main ones a e he ollowing. The i s is he low o he adhesi e in o
he mic os uc u e o he subs a e p o iding mechanical in e locking be ween he
subs a e and he adhesi e. The second is he physical bonding be ween he subs a e and
he adhesi e due o Van de Waals o ces. Typically, he Van de Waals o ces do no
con ibu e much o he o e all adhesion o ce. Finally, he hi d is he chemical bonding,
which includes co alen , ionic and me allic connec ions, which a e ypically much
s onge han he physical bonds. Howe e , he chemical bonding be ween he di e en
ma e ials is mo e complica ed and he numbe o he a ailable bonding si es is limi ed.
Thus, due o i s complex na u e, he adhesion o ces a e e y dependen on many
ac o s: chemical composi ion o adhesi e and subs a e, subs a e mic os uc u e, ough-
ness, su ace ene gy, we abili y and cleanness. The mos e ec i e way o imp o e he
adhesi e s eng h is he p e- ea men and p epa a ion o he su aces being bonded. One
o he widely used app oaches o imp o e he chemical bonding is use o plasma o clean
and ac i a e he su ace o bonding by c ea ing addi ional bonding si es.
Au omo i e high empe a u e adia o s (see Figu e 1a) unde go a ious
empe a u es and p essu e condi ions du ing hei se ice li es, so app op ia e s eng h
o bonding mus be ensu ed. Au omo i e companies ypically equi e he adia o o
wi hs and in e nal p essu e o 2.5 ba a a maximal ope a ion empe a u e o 125 °C.
Conside ing he sa e y ac o equal o 3 be ween he ope a ing and bu s p essu e, we
conside he equi ed bu s p essu e as 7.5 ba (0.75 MPa). The shea s eng h equi ed o
wi hs and his p essu e can be calcula ed as:
σ ≈ 0.75 MPa × 24/15 = 1.2 MPa
whe e 24 mm is he wid h o he su ace unde p essu e and 15 mm is he heigh o he
bonding o e lap. Thus, shea s ess a leas o 1.2 MPa will be equi ed o conside he
adhesi e able o wi hs and he o ces due o p essu e p esence.
The s eng h o adhesi e bonding is also e y sensi i e o he s ess di ec ion.
Typically, adhesi e connec ion esis s he ensile and shea s ess well. On he o he hand,
he bonding is e y sensi i e o piling as i causes s ess concen a ion in a small a ea. In
his case, he bonding is i s ly b oken on one side o he bonding a ea, and he ailu e
hen p oceeds h ough he a ea des oying he whole bonding. To p e en piling he igh
design o he bonding connec ion should be applied. Figu e 1b shows a d awing o he
Figu e 2.
Adhesi e and cohesi e join ailu es acc. o EN ISO 10365:1992. (The igu e was modi ied
acco ding o [10]).
On he one hand, cohesi e ailu e wi hin he adhesi e o in he subs a e is he
p e e ed ype o ailu e because wi h his ype, he maximum s eng h o he ma e ials in
he join has been eached. On he o he hand, he cohesi e ailu e ound by an ele a ed
empe a u e es may indica e ha he adhesi e los i s s eng h and is no sui able o
his empe a u e.
Vice e sa, adhesi e ailu e means ha he adhesi e inne s eng h is highe han he
o ces be ween he adhesi e and he subs a e. The e a e se e al di e en mechanisms
o he adhesion, bu he main ones a e he ollowing. The i s is he low o he adhesi e
in o he mic os uc u e o he subs a e p o iding mechanical in e locking be ween he
subs a e and he adhesi e. The second is he physical bonding be ween he subs a e
and he adhesi e due o Van de Waals o ces. Typically, he Van de Waals o ces do no
con ibu e much o he o e all adhesion o ce. Finally, he hi d is he chemical bonding,
which includes co alen , ionic and me allic connec ions, which a e ypically much s onge
han he physical bonds. Howe e , he chemical bonding be ween he di e en ma e ials is
mo e complica ed and he numbe o he a ailable bonding si es is limi ed.
Thus, due o i s complex na u e, he adhesion o ces a e e y dependen on many
ac o s: chemical composi ion o adhesi e and subs a e, subs a e mic os uc u e, ough-
ness, su ace ene gy, we abili y and cleanness. The mos e ec i e way o imp o e he
adhesi e s eng h is he p e- ea men and p epa a ion o he su aces being bonded. One
o he widely used app oaches o imp o e he chemical bonding is use o plasma o clean
and ac i a e he su ace o bonding by c ea ing addi ional bonding si es.
Au omo i e high empe a u e adia o s (see Figu e 1a) unde go a ious empe a u es
and p essu e condi ions du ing hei se ice li es, so app op ia e s eng h o bonding mus
be ensu ed. Au omo i e companies ypically equi e he adia o o wi hs and in e nal
p essu e o 2.5 ba a a maximal ope a ion empe a u e o 125
◦
C. Conside ing he sa e y
ac o equal o 3 be ween he ope a ing and bu s p essu e, we conside he equi ed bu s
p essu e as 7.5 ba (0.75 MPa). The shea s eng h equi ed o wi hs and his p essu e can
be calcula ed as:
σ≈0.75 MPa ×24/15 = 1.2 MPa
whe e 24 mm is he wid h o he su ace unde p essu e and 15 mm is he heigh o he
bonding o e lap. Thus, shea s ess a leas o 1.2 MPa will be equi ed o conside he
adhesi e able o wi hs and he o ces due o p essu e p esence.
The s eng h o adhesi e bonding is also e y sensi i e o he s ess di ec ion. Typically,
adhesi e connec ion esis s he ensile and shea s ess well. On he o he hand, he bonding
is e y sensi i e o piling as i causes s ess concen a ion in a small a ea. In his case, he
bonding is i s ly b oken on one side o he bonding a ea, and he ailu e hen p oceeds
h ough he a ea des oying he whole bonding. To p e en piling he igh design o
he bonding connec ion should be applied. Figu e 1b shows a d awing o he bonding
connec ion applied o glue he hea exchange co e inside o he mani old. The bonding is
P ocesses 2022,10, 806 4 o 15
designed in such a way ha he e is no adhesi e piling, he ensile s esses a e small, and
he dominan s ess is he shea s ess. The e o e, we expe imen ally measu ed he shea
s eng h as he main pa ame e o es ima e he bonding esis ance.
We can conclude ha de e mina ion o he join ’s ul ima e s eng h a an ele a ed
empe a u e is c ucial o p edic ing join du abili y e en i he du abili y a an ele a ed
empe a u e may be much lowe han in i s no mal wo king condi ions. The goals o his
s udy a e as ollows:
•
To expe imen ally s udy a wide ange o adhesi es and de e mine hei esis ance o
high empe a u es;
•
Fo pa icula plas ic subs a es, o de e mine he bes adhesi e o high empe a u es;
•To es ima e he in luence o he cold plasma su ace ea men ;
•To choose and ecommend success ul adhesi es.
2. Expe imen al Sec ion
2.1. Tes ed Plas ic Ma e ials
Glass epoxy shee G11 180
◦
C, EPGC308 ype acco ding o EN-60893. Epoxy shee s
a e made om modi ied glass ab ic and epoxy esin wi h he addi ion o ille . They a e
cha ac e ized by hei excellen mechanical and elec ical insula ing p ope ies, which a e
e ained e en a highe empe a u es, and by hei esis ance o c acking. They a e used in
he p oduc ion o componen s wi h good mechanical and elec ical p ope ies, o elec ical
equipmen a highe empe a u es o in humid en i onmen s, and o s essed elec ical
insula ing componen s, such as chassis, body equipmen , housing pa s o dis ibu ion
boa ds, and ans o me s [11].
ERTALON Polyamide 66 is illed wi h 30% glass ibe s. Compa ed wi h i gin PA 66,
his 30% glass ibe ein o ced and hea s abilized nylon g ade o e s inc eased s eng h,
s i ness, c eep esis ance and dimensional s abili y while e aining excellen wea esis ance
and high se ice empe a u es [12].
TECATRON-GF40 black is a 40% glass ibe - ein o ced PPS. Because o he high le el o
glass ibe ein o cemen , TECATRON-GF40 black demons a es excellen igidi y and e y
high s eng h a high empe a u es compa ed o unmodi ied PPS (TECATRON na u al).
High he mal s abili y, high dimensional s abili y, e y good chemical esis ance, good
elec ical and he mal insula ion and good esis ance o s e iliza ion ound o he p o ile o
his modi ied PPS. These ma e ial p ope ies make glass- illed PPS sui able o use in pa s
ha a e exposed o high s a ic loads o e long pe iods in high empe a u es. Howe e , he
inhe en chemical s uc u e along wi h he addi ion o glass ibe s ends o c ea e oughness
issues wi h his ma e ial. As glass ibe s end in some cases o ha e a ma ked ab asi e e ec
on ma ing su aces, his PPS composi e may be less sui able o sliding applica ions [
13
].
Table 1 e iews he mechanical p ope ies o he desc ibed ma e ials.
Table 1. Mechanical p ope ies o he es ed plas ic ma e ials.
Ma e ial Used Glass Epoxy Shee G11 PA66-GF30 PPS-GF40
Resin and ein o cemen epoxide + glass ab ic PA66 + glass ibe s PPS + glass ibe s
Flexu al modulus, MPa 26,000 - 4600
Tensile s eng h, MPa 400 85 83
No ch impac s eng h pa allel o
lamina ion (Cha py), KJ/m2100 6 24
Shea ing s eng h pa allel o
lamina ions, MPa 50 - -
Densi y, g/cm31.9 1.29 1.63
Tempe a u e index (TI) o
Tempe a u e o De lec ion, ◦C180 150 230
Wa e abso p ion (3 mm hick) 9 mg
56 mg/96 h acco ding o ISO 62
0.01%/96 h acco ding o ISO 62
P ocesses 2022,10, 806 5 o 15
2.2. Tes ed Adhesi es
An o e iew o he es ed adhesi es is shown in Table 2 oge he wi h a b ie desc ip-
ion o each. The adhesi es es ed we e selec ed based on wo main equi emen s, high
glass ansi ion empe a u e Tg and he lexibili y o wi hs and dimensional change due
o he mal expansion. All he es ed adhesi es we e wo-componen epoxies in ended o
bonding o encapsula ing.
Table 2. Re iew o es ed adhesi es.
Manu ac u e B and
Name Type Tg, ◦COpe a ion Temp.
Range, ◦CB ie Desc ip ion and Re e ence
Rel ek Bondi
B-46 - −65–135 An adhesi e o bonding dissimila ma e ials, such as plas ics,
including UHMW, HDPE, PP, PET, PEEK, PPS, PBT, Ace al,
ETFE, PVC, PVCF, PVDF, ABS, ECTFE, polyamide, polyimide,
ubbe , and u e hane compounds on me al, glass, composi es,
cemen , wood, and cellulose [14].
B-481 - up o 170
B-536 - -
Elan as
Elan- ech
AS60/AW60 135 up o 150
Excellen he mal and chemical esis ance, high modulus, igid,
e y good o magne s.
ASM 031 Fe i e, syn hesized ma e ials, magne s, he mally esis an
ma e ials [15].
Epoxyli e E8628 127 up o 204
E 8628 Hi Temp- wo-componen , low iscosi y compound o
se ice empe a u e up o 200
◦
C. Fo po ing o collec o ings,
slip ings and ield coils whe e igidi y and dimensional
s abili y a e equi ed [16].
GRM
LG700/HG700
- up o 120
Lamina ing sys em o RIM, RTM, acuum echnology, and
hand lamina ing. Ex emely low iscosi y enables p ocessing
o e y ligh lamina es. High eac i i y. Wo king ime om
25 min o 3 h. Ve y good hea esis ance and high lexibili y
e en when pos -cu ed a oom empe a u e [17].
Epoxies
20-3001 NC - −50 o +150
20-3001 NC is a low iscosi y, un illed epoxy po ing and
encapsula ing sys em which o ms a bubble- ee glass-like
inish when cu ed [18].
20-3302 NC - −45 o +135
20-3302 is a low iscosi y sys em designed o L.E.D.
encapsula ing, ibe op ics, and any po ing o adhesi e
applica ion equi ing op imum cla i y. This epoxy sys em also
p o ides a bubble- ee and glass-smoo h inish [19].
Gi bach Gimapox EL6 160 up o 160
Epoxy esin sys em has a glass ansi ion empe a u e o up o
160 ◦C and e y high he mal s abili y. The ma e ial has good
chemical esis ance [20].
Ha el LH 301 - up o 160
Epoxy esin LH 301 is a esin which makes i possible o
achie e a empe a u e esis ance o abou 160 ◦C wi h a
ha dene H 513. When cu ing amines o polyamines, i o e s
high mechanical p ope ies, and good chemical and he mal
esis ance. Ra io LH 301:H 513 = 100:22 The p oduc mus be
cu ed a empe a u es o min. 50 ◦C o 4 h, and o achie e
maximum empe a u e esis ance, i is hen app op ia e o
ha den i by g adually hea ing i o 160 ◦C [21].
5 M Le oxi LH 190 - up o 150
This wo-componen epoxy adhesi e is composed o pa A
and pa B and ha dens a a highe empe a u e. The adhesi e
is in ended o bonding o me als and applica ions wi h high
empe a u e esis ance [22].
Henkel Loc i e
EA 9483 61 -
EA 9483 is a 2-pa , ul a-clea , lowing, gene al pu pose epoxy
adhesi e sui able o bonding and po ing whe e op ical cla i y
and high s eng h a e equi ed [23].
EA 9497 116 -
LOCTITE®(Henkel AG, Düsseldo , Ge many) EA 9497 is a
2-pa , g ey epoxy adhesi e o s uc u al bonding ha o e s
high echnical pe o mance. The p oduc p o ides high
empe a u e esis ance up o +180
◦
C o hea - esis an bonding
and illing. I is he mally conduc i e and deli e s high
comp ession s eng h. I is ideal o bonding me al
componen s [24].

P ocesses 2022,10, 806 6 o 15
2.3. P epa a ion o Samples
The samples we e made by gluing he desks wi h a slip su ace o 12.5
×
24.5 mm. Fo
he glass epoxy shee an addi ional 33
×
24.5 mm squa e was bonded in o de o ha e he
jaws o he ensile es machine on one plane (see Figu e 3 o de ails). Fo PA and PPS,
samples we e made by CNC milling. Such shapes o samples we e used o p e en o sion
in he specimen and ensu e one-dimension loading (shea s ess) o he slip su ace (see
Figu e 4b). Bonding su aces we e ea ed wi h ca e be o e he applica ion o he adhesi e.
Epoxy shee samples we e cleaned and sandpape ed sligh ly (size 200 pape ) because he
su ace was e y smoo h. The milled samples (PA and PPS) we e no sandpape ed bu we e
ung eased o emo e possible oil impu i ies om he ools. Fo PA and PPS, an addi ional
bunch o samples was p epa ed and ea ed wi h cold plasma because i ep esen s an
e icien , clean and economical al e na i e o ac i a ing he su aces o he moplas ics [
25
].
The Relyon PZ2 hand plasma Piezo b ush [
26
] was applied closely be o e he applica ion
o he adhesi e ( o up o 20 min) because he ageing o he plasma- ea ed su ace educes
he plasma e ec .
P ocesses 2022, 10, x FOR PEER REVIEW 6 o 16
Henkel Loc i e
EA
9483 61 -
EA 9483 is a 2-pa , ul a-clea , lowing, gene al pu pose epoxy adhesi e
sui able o bonding and po ing whe e op ical cla i y and high s eng h a e
equi ed [23].
EA
9497 116 -
LOCTITE® (Henkel AG, Düsseldo , Ge many)EA 9497 is a 2-pa , g ey epoxy
adhesi e o s uc u al bonding ha o e s high echnical pe o mance. The
p oduc p o ides high empe a u e esis ance up o +180 °C o hea - esis an
bonding and illing. I is he mally conduc i e and deli e s high comp ession
s eng h. I is ideal o bonding me al componen s [24].
2.3. P epa a ion o Samples
The samples we e made by gluing he desks wi h a slip su ace o 12.5 × 24.5 mm. Fo
he glass epoxy shee an addi ional 33 × 24.5 mm squa e was bonded in o de o ha e he
jaws o he ensile es machine on one plane (see Figu e 3 o de ails). Fo PA and PPS,
samples we e made by CNC milling. Such shapes o samples we e used o p e en o sion
in he specimen and ensu e one-dimension loading (shea s ess) o he slip su ace (see
Figu e 4b). Bonding su aces we e ea ed wi h ca e be o e he applica ion o he adhesi e.
Epoxy shee samples we e cleaned and sandpape ed sligh ly (size 200 pape ) because he
su ace was e y smoo h. The milled samples (PA and PPS) we e no sandpape ed bu
we e ung eased o emo e possible oil impu i ies om he ools. Fo PA and PPS, an
addi ional bunch o samples was p epa ed and ea ed wi h cold plasma because i
ep esen s an e icien , clean and economical al e na i e o ac i a ing he su aces o
he moplas ics [25]. The Relyon PZ2 hand plasma Piezo b ush [26] was applied closely
be o e he applica ion o he adhesi e ( o up o 20 min) because he ageing o he plasma-
ea ed su ace educes he plasma e ec .
Figu e 3. The size o he es ed samples made o G11 glass epoxy shee s.
Figu e 3. The size o he es ed samples made o G11 glass epoxy shee s.
P ocesses 2022, 10, x FOR PEER REVIEW 7 o 16
(a) (b)
Figu e 4. (a) Aluminum ame wi h glass epoxy samples; (b) milled PA66-GF30 sample.
The adhesi es we e p epa ed acco ding o he manu ac u e ’s manuals and applied
wi h he ecommended hicknesses. The applica ion me hods a ied depending on he
iscosi y o he pa icula adhesi e. The low- iscosi y adhesi es we e applied wi h a
d oppe so ha he en i e shea su ace was co e ed wi h a con inuous laye o adhesi e.
The o e lows o he adhesi e in he join s we e wiped o wi h a co on swab. The
samples we e hen ixed in he cells in he aluminum pla e (see Figu e 4a), and he bonded
join s we e loaded wi h weigh s. The samples we e ixed and loaded (up o 1.5 kg, 50 kPa
p essu e) his way in o de o he adhesi e o be cu ed acco ding o he manu ac u e s’
ecommenda ions. A e adhesi e cu ing, he end aces o he join s we e oughened wi h
sandpape (size 200) o p e en hem slipping in he clamping jaws o he ensile machine.
Th ee samples we e p epa ed and es ed o each pai o he subs a e-adhesi e.
2.4. Tes ing Me hod
A e cu ing, he samples we e es ed o ensile shea s eng h in acco dance wi h
ČSN EN 1465 (Czech e sion o BS EN 1465: 2009-Adhesi es. De e mina ion o ensile lap-
shea s eng h o bonded assemblies). ISO 4587 p o ides a s anda d me hod o de e mine
he lap-shea s eng h o a bond be ween wo igid es specimens. Each specimen should
be 100 × 25 × 1.6 mm. These a e bonded wi h an o e lap o 12.5 mm and clamped o e a
37.5 mm leng h a each end. The o ce equi ed o pull he specimens apa is hen
eco ded. ISO 4587 is used o quali y con ol in many indus ies, including ae ospace,
au omo i e, and consume goods manu ac u ing. Each sample was clamped in he jaws
o he ensile machine (Z010 TE, Zwick & Roell) in a closed hea ed empe a u e chambe
(see Figu e 5) [27]. The chambe was hea ed o he equi ed empe a u e and he sample
was empe ed o 5 min p io o es ing. A e empe ing, he machine was s a ed and he
shea s ess was measu ed a a speed o 10 mm/min. The slip su aces o he b oken
samples we e pho odocumen ed o e alua e he ype o ailu e.
Figu e 4. (a) Aluminum ame wi h glass epoxy samples; (b) milled PA66-GF30 sample.
The adhesi es we e p epa ed acco ding o he manu ac u e ’s manuals and applied
wi h he ecommended hicknesses. The applica ion me hods a ied depending on he
iscosi y o he pa icula adhesi e. The low- iscosi y adhesi es we e applied wi h a
d oppe so ha he en i e shea su ace was co e ed wi h a con inuous laye o adhesi e.
The o e lows o he adhesi e in he join s we e wiped o wi h a co on swab. The samples
P ocesses 2022,10, 806 7 o 15
we e hen ixed in he cells in he aluminum pla e (see Figu e 4a), and he bonded join s we e
loaded wi h weigh s. The samples we e ixed and loaded (up o 1.5 kg,
50 kPa p essu e)
his
way in o de o he adhesi e o be cu ed acco ding o he manu ac u e s’ ecommenda ions.
A e adhesi e cu ing, he end aces o he join s we e oughened wi h sandpape (size 200)
o p e en hem slipping in he clamping jaws o he ensile machine. Th ee samples we e
p epa ed and es ed o each pai o he subs a e-adhesi e.
2.4. Tes ing Me hod
A e cu ing, he samples we e es ed o ensile shea s eng h in acco dance wi h ˇ
CSN
EN 1465 (Czech e sion o BS EN 1465: 2009-Adhesi es. De e mina ion o ensile lap-shea
s eng h o bonded assemblies). ISO 4587 p o ides a s anda d me hod o de e mine he
lap-shea s eng h o a bond be ween wo igid es specimens. Each specimen should be
100
×
25
×
1.6 mm. These a e bonded wi h an o e lap o 12.5 mm and clamped o e a 37.5
mm leng h a each end. The o ce equi ed o pull he specimens apa is hen eco ded.
ISO 4587 is used o quali y con ol in many indus ies, including ae ospace, au omo i e,
and consume goods manu ac u ing. Each sample was clamped in he jaws o he ensile
machine (Z010 TE, Zwick & Roell, Ulm, Ge many) in a closed hea ed empe a u e chambe
(see Figu e 5) [
27
]. The chambe was hea ed o he equi ed empe a u e and he sample
was empe ed o 5 min p io o es ing. A e empe ing, he machine was s a ed and
he shea s ess was measu ed a a speed o 10 mm/min. The slip su aces o he b oken
samples we e pho odocumen ed o e alua e he ype o ailu e.
P ocesses 2022, 10, x FOR PEER REVIEW 8 o 16
Figu e 5. Epoxy shee sample ixed in he clamping jaws o he hea ed chambe o he ensile
machine Z010 TE, Zwick & Roell.
3. Resul s and Discussion
3.1. Glass Rein o ced Epoxy Shee s G11, 130 °C and 160 °C
Epoxy shee ma e ial is a good base ma e ial o es he gluing p ope ies as i has
high mechanical s eng h and he mal esis ance, good adhesion p ope ies, and
dimensional s abili y (low he mal expansion due o ein o cemen wi h glass ab ic). The
i s ound o es ing a 130 °C showed ha many adhesi es do no wi hs and he
empe a u e (cohesi e ailu es), so es ing a highe empe a u es was con inued only
wi h success ul ones.
A 130 °C, he LH 301 adhesi e join had he highes s eng h, while he s eng h o
he Bondi B-46 adhesi e was he lowes (see Table 3 o esul s). Fo he Bondi B-46
adhesi e, wo o he h ee bonded join s we e b oken be o e s a ing he es du ing
condi ioning. The same was ue o he join bonded wi h 20-3302 NC. One o he easons
could be he e ec o a wa m ai s eam causing some ib a ion o he sample. LH 301 and
AS60/AW60, he wo s onges join s, showed a sligh slip o he specimens in he jaws
du ing he es . He e, i seems ha he join will no come apa spon aneously unless i is
mechanically s essed. Fo he LH 301 adhesi e sample, i is clea ( om he pealed-o
shea su aces) ha he adhesi e join only came loose wi h he des uc ion o he
ibe glass boa d ma e ial (cas ing esin). The cas ing esin was li e ally o n down o a
laye o glass ab ic. The di e ence in s eng h be ween he bes and wo s adhesi e is one
o de o magni ude. The ou bes adhesi es showed a s eng h in he ange o 2.9–2.6
MPa, wi h ano he adhesi e (LG700/HG700) expe iencing a dec ease in s eng h o almos
hal .
Table 3. O e iew o es ed adhesi es, cu ing empe a u es, and shea s eng h es ed wi h glass
epoxy shee G11.
Adhesi e
Adhesi e
Amoun
Cu ing Condi ions
Shea S eng h a 130 °C
Shea S eng h a 160 °C
Failu e Type a 160 °C
Figu e 5.
Epoxy shee sample ixed in he clamping jaws o he hea ed chambe o he ensile machine
Z010 TE, Zwick & Roell.
P ocesses 2022,10, 806 8 o 15
3. Resul s and Discussion
3.1. Glass Rein o ced Epoxy Shee s G11, 130 ◦C and 160 ◦C
Epoxy shee ma e ial is a good base ma e ial o es he gluing p ope ies as i has high
mechanical s eng h and he mal esis ance, good adhesion p ope ies, and dimensional
s abili y (low he mal expansion due o ein o cemen wi h glass ab ic). The i s ound o
es ing a 130
◦
C showed ha many adhesi es do no wi hs and he empe a u e (cohesi e
ailu es), so es ing a highe empe a u es was con inued only wi h success ul ones.
A 130
◦
C, he LH 301 adhesi e join had he highes s eng h, while he s eng h o he
Bondi B-46 adhesi e was he lowes (see Table 3 o esul s). Fo he Bondi B-46 adhesi e,
wo o he h ee bonded join s we e b oken be o e s a ing he es du ing condi ioning.
The same was ue o he join bonded wi h 20-3302 NC. One o he easons could be he
e ec o a wa m ai s eam causing some ib a ion o he sample. LH 301 and AS60/AW60,
he wo s onges join s, showed a sligh slip o he specimens in he jaws du ing he es .
He e, i seems ha he join will no come apa spon aneously unless i is mechanically
s essed. Fo he LH 301 adhesi e sample, i is clea ( om he pealed-o shea su aces)
ha he adhesi e join only came loose wi h he des uc ion o he ibe glass boa d ma e ial
(cas ing esin). The cas ing esin was li e ally o n down o a laye o glass ab ic. The
di e ence in s eng h be ween he bes and wo s adhesi e is one o de o magni ude. The
ou bes adhesi es showed a s eng h in he ange o 2.9–2.6 MPa, wi h ano he adhesi e
(LG700/HG700) expe iencing a dec ease in s eng h o almos hal .
Table 3.
O e iew o es ed adhesi es, cu ing empe a u es, and shea s eng h es ed wi h glass
epoxy shee G11.
Adhesi e
Adhesi e
Amoun Cu ing Condi ions Shea S eng h a 130 ◦C Shea S eng h a 160 ◦C Failu e Type a 160 ◦C
(mg) (h) (◦C) (MPa)
B-46 5.3 4 93 0.29 ±0
B-481 6.7 3 93 1.27 ±0.13 1.18 ±0.21 A */100%
B-536 13.9 1.5 93 1.45 ±0.22
AS60/AW60
48.4 15 23 2.83 ±0.18
3 130 1.59 ±0.23 A */100%
ASM 031 10.3 2 120 0.73 ±0.13
4 140
E8628 – 4 177 0.53 ±0.23
LG700/HG700
5.6 2 120 1.52 ±0.06
20-3001 NC 9.6 16 25 0.94 ±0.05
20-3302 NC 9.9 2 52 0.64 ±0
EL6 3.9 24 25 1.00 ±0.43
2 120
LH 301 27.3 – – 2.94 ±0.05 1.21 ±0.17 A */90%
LH 190 67.5
24 22
2.75 ±0.18
0.5 60
1 100
3 120 1.63 ±0.18 A */100%
EA 9483 16.0 168 22 1.36 ±0.1
EA 9497 54.8 24 22 2.59 ±0.04 1.42 ±0.34 A */90%
0.25 120
* adhesi e ac u e.– ailu e a he adhesi e-bonded ma e ial in e ace.
In addi ion o he shea s eng h alues, he way he join s ac u e also p o ides
impo an in o ma ion abou he join quali y. In he specimens examined, ou ypical
ac u e ypes we e obse ed: cohesi e ac u e, adhesi e ac u e, ac u e a he ma e ial
laye and mixed ac u e. The ma e ial laye ailu e is cha ac e ized by damage o he
base ma e ial- ibe s o pa icles a e o n om he su ace. Adhesi e ailu e occu s on he
bo de be ween he base ma e ial and he adhesi e (all he adhesi e emains on one o
P ocesses 2022,10, 806 9 o 15
he adhe en s). Cohesi e ailu e occu s when he adhesi e loses i s s eng h and b eaks
(pa icles o he adhesi e emain on bo h adhe en s).
Tes s a a empe a u e o 130
◦
C show ha only 5 adhesi es wi hs and he inc eased
empe a u e wi hou signi ican so ening and loss o s eng h, hus showing ha i is an
adhesi e ailu e. The o he adhesi es did no wi hs and he empe a u e and he bonded
connec ions we e b oken cohesi ely. The bes adhesi es we e also es ed a 160
◦
C and he
bes esul was p o ided by LH 190, while AS60/AW60 also displayed e y good s eng h.
LH 109 and AS60/AW60 can be ecommended o gluing glass-lamina e. Figu e 6shows
he slip su aces o he samples wi h e iden ype o he ailu e, adhesi e ype. Ou o
all es ed adhesi es he bes -pe o ming ones we e wo-componen epoxy esins applied
on epoxy glass shee subs a e and cu ed a ele a ed empe a e. Due o his ac , some
chemical bonding can occu ega dless o he ac ha he epoxy o subs a e was ully
cu ed long be o e he applica ion o adhesi e epoxies. Ne e heless, wi h empe a u e
inc easing o 160
◦
C, he o ces o chemical bonding we e educed, and in e nal s esses
due o di e en he mal expansion occu ed (subs a e epoxy shee s ha e lowe he mal
expansion coe icien due o p esence o glass ab ic). These ac o s oge he wi h educ ion
o s eng h o adhesi es hemsel es ha e caused he adhesi e ailu es o he es ed samples.
Resul s o shea s eng h a ele a ed empe a u es a e signi ican ly lowe han hose a
no mal condi ions, showing ha he empe a u e ac o is c ucial. Fo example, he Henkel
Loc i e bonding guide [
28
] e e s o lap shea s eng h o epoxy o epoxy bonding o up o
21 MPa ( o Loc i e 4307 adhesi e). In his case, he bonding s eng h is highe han he
subs a e s eng h. Ne e heless, he e ec o ele a ed empe a u e is no e lec ed as es s
we e pe o med o no mal condi ions. The e we e no da a a ailable o epoxy- o-epoxy
bonding es ed a ele a ed empe a u e o 130 and 160 ◦C.
P ocesses 2022, 10, x FOR PEER REVIEW 10 o 16
connec ions we e b oken cohesi ely. The bes adhesi es we e also es ed a 160 °C and
he bes esul was p o ided by LH 190, while AS60/AW60 also displayed e y good
s eng h. LH 109 and AS60/AW60 can be ecommended o gluing glass-lamina e. Figu e
6 shows he slip su aces o he samples wi h e iden ype o he ailu e, adhesi e ype.
Ou o all es ed adhesi es he bes -pe o ming ones we e wo-componen epoxy esins
applied on epoxy glass shee subs a e and cu ed a ele a ed empe a e. Due o his ac ,
some chemical bonding can occu ega dless o he ac ha he epoxy o subs a e was
ully cu ed long be o e he applica ion o adhesi e epoxies. Ne e heless, wi h
empe a u e inc easing o 160 °C, he o ces o chemical bonding we e educed, and
in e nal s esses due o di e en he mal expansion occu ed (subs a e epoxy shee s ha e
lowe he mal expansion coe icien due o p esence o glass ab ic). These ac o s oge he
wi h educ ion o s eng h o adhesi es hemsel es ha e caused he adhesi e ailu es o
he es ed samples. Resul s o shea s eng h a ele a ed empe a u es a e signi ican ly
lowe han hose a no mal condi ions, showing ha he empe a u e ac o is c ucial. Fo
example, he Henkel Loc i e bonding guide [28] e e s o lap shea s eng h o epoxy o
epoxy bonding o up o 21 MPa ( o Loc i e 4307 adhesi e). In his case, he bonding
s eng h is highe han he subs a e s eng h. Ne e heless, he e ec o ele a ed
empe a u e is no e lec ed as es s we e pe o med o no mal condi ions. The e we e no
da a a ailable o epoxy- o-epoxy bonding es ed a ele a ed empe a u e o 130 and 160
°C.
Figu e 6. F ac u e su aces o he 4 bes -pe o ming adhesi es–130 °C es . The slip su aces o all
he adhesi es show he p esence o he adhesi e on bo h sides o he samples which can be
in e p e ed as cohesi e ailu e. Howe e , in all cases, he majo i y o he adhesi e laye s we e on
one side, showing he na u e o he adhesi e ailu e na u e.
3.2. PA66-GF30, 110 °C and 160 °C
Unlike epoxy glass-en o ced shee s, he polyamides a e di icul o bond because hey
a e hyd ophobic, chemically ine and possess poo su ace we abili y. All hese ac o s
make p ope p e- ea men e y impo an , including cleaning, emo ing hyd oca bon
con amina es, oughening wi h sandpape and plasma su ace ea men . All o hose
we e used o ensu e easonable adhesion o ele a ed empe a u es.
The s eng h o he bonded join s is gi en in Table 4, oge he wi h he e alua ion o
he ype o ailu e. The le e A indica es an adhesi e ailu e ( ailu e a he adhesi e-
bonded ma e ial in e ace), and he le e C indica es a signi ican cohesi e ailu e in he
adhesi e (adhesi e emained on bo h su aces o he bonded join ). An image o he h ee
b oken join s a e he es a 110 °C is shown in Figu e 7. Howe e , as he su ace o he
Figu e 6.
F ac u e su aces o he 4 bes -pe o ming adhesi es—130
◦
C es . The slip su aces o all he
adhesi es show he p esence o he adhesi e on bo h sides o he samples which can be in e p e ed as
cohesi e ailu e. Howe e , in all cases, he majo i y o he adhesi e laye s we e on one side, showing
he na u e o he adhesi e ailu e na u e.
3.2. PA66-GF30, 110 ◦C and 160 ◦C
Unlike epoxy glass-en o ced shee s, he polyamides a e di icul o bond because hey
a e hyd ophobic, chemically ine and possess poo su ace we abili y. All hese ac o s
make p ope p e- ea men e y impo an , including cleaning, emo ing hyd oca bon