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Signi icance o Adhesion Theo ies in A ea o Flexible Bonded
S uc u al Join s in Cons uc ion Sec o
Ba bo a Nečaso á 1
1 B no Uni e si y o Technology, Ve eří 331/95, B no 602 00, Czech Republic
[email p o ec ed]
Abs ac . The issue o bonding has been a pa o humani y h oughou i s his o y. The g ea es
de elopmen in his a ea occu ed in he second hal o he 20 h cen u y and he issue o
bonding has gained a lo o in e es om he scien i ic communi y. O e he pas 80 yea s,
he e has been a signi ican inc ease in scien i ic esea ch and g an s aimed a de ining
adhesion. We now know ha examining he adhesion o ma e ials, de e mining he adhesi e
p ope ies o simply e alua ing he es esul s and assessing he ailu e o he es specimens is
no possible wi hou unde s anding he basic p inciples and heo ies o bonding, i.e. adhesi e
joining. The p esen ed pape is ocused on he desc ip ion o undamen al adhesion heo ies
and hei usage in he ield o s uc u al bonding in cons uc ion indus y. The impo ance o
unde s anding o adhesi e p ope ies o used p oduc s is demons a ed on an example o ou
di e en su aces in combina ion wi h ep esen a i es o high s eng h lexible adhesi e
sys ems in ended o açade applica ions. Rep esen a i es wi h high su ace pola i y, medium-
high pola i y and low pola i y we e delibe a ely selec ed. The one-way ANOVA was
pe o med o analyse he impac o su ace adhesi e p ope ies on adhesion o bonded join s. I
was con i med ha he iskies is bonding o polyme -based ma e ials. Fo all selec ed
ma e ials i was concluded ha he hypo heses o he adso p ion heo y, which, o some ex en ,
also includes he assump ions o o he adhesi e heo ies, seem o be he mos undamen al o
he p esen ed esea ched a ea.
1. In oduc ion
The issue o bonding has been a pa o humani y h oughou i s his o y. While by he beginning o he
20 h cen u y, all adhesi es used un il hen we e en i ely na u al-based, only wi h he end o he second
wa e o he indus ial e olu ion came he i s adhesi e based on syn he ic polyme s. As epo ed by
Pe ie [1], nowadays, i is almos impossible o ind a p oduc commonly used in households, indus y,
anspo a ion, o anywhe e else ha does no con ain adhesi e in any o m. We now also know ha
examining he adhesion o ma e ials, de e mining he adhesi e p ope ies, o simply e alua ing he es
esul s and assessing he ailu e o he es samples is no possible wi hou unde s anding he basic
p inciples and heo ies o bonding because adhesion o ma e ials is no only ela ed o adhesi e
p ope ies bu also o he esis ance o he bonded su ace o mechanical s esses [1-3]. The
du abili y/s eng h and li espan o a bonded join is mos o en a ec ed by ou basic pa ame e s [2-4]:
• adhesion o he adhesi e o he adhe end;
• adhesi e p ope ies o he adhe ends;
• cohesion o he adhesi e; and
• du abili y/s eng h o he adhe ends, as he bonded join is as s ong as he adhe ends a e
esis an .
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The main p e equisi e o a pe ec join o wo adhe ends is hei ideal adhesi e p ope ies [1-5].
As men ioned abo e, scien is s ha e been s udying he phenomenon o adhesion in mode n his o y
since he 1920s [3,6], and mo e a en ion has been paid o his issue since he 1940s [1]. Tha is
p ima ily why we can use se e al heo e ical models o de ine he bond o he adhesi e and he
adhe ends. The so-called adi ional ones include mechanical, elec os a ic, di usion and adso p ion
heo ies, see Table 1 [3,6]. I is ob ious ha he numbe o heo ies has been g adually expanded, o
mo e p ecisely ha some me hods has been elabo a ed in mo e de ail wi h he de elopmen o
echnologies and new ma e ials. Howe e , he app oach o he assessmen o adhe ends has emained
almos unchanged. The assessmen o he adhe end based on he use o only one heo y is insu icien ,
as he de ini ion o adhesion is based on he sea ch o in e disciplina y connec ions.
Table 1. O e iew o basic adhesion heo ies [3,6].
T adi ional Theo ies
Cu en Theo ies
Scale o Assessmen
Mechanical
Mechanical
mic oscopic
Elec os a ic
Elec os a ic
mac oscopic
Di usion
Di usion
molecula
Adso p ion
We abili y
molecula
Chemical
a omic
Weak – Bounda y – Laye
molecula
Acid – Base
molecula
1.1. Mechanical heo y
This is one o he basic heo ies o adhesion which was in oduced by McBain and Hopkins a ound
1925 [7]. This heo y is applicable mainly o po ous ma e ials, as i is based on he assump ion ha he
su ace o each ma e ial is w inkled in some way which allows he adhesi e o pene a e be e in o all
gaps and i egula i ies. Thus, he heo y wo ks be e o ough o addi ionally oughened su aces
while i is no applicable o smoo h su aces on i s own. As men ioned abo e, he p ope ies o he
join a e no only a ec ed by he adhesi e p ope ies o he adhe end bu also by he p ope ies o he
adhesi e i sel . I is he e o e necessa y o use a high iscosi y adhesi e o ul il he mechanical heo y
hypo hesis. Pa o he p esen ed pape is de o ed o he e i ica ion o he hypo hesis o his heo y,
when ma e ials wi h di e en deg ees o po osi y and wi h di e en su ace pola i y we e selec ed o
his pu pose.
1.2. Elec os a ic heo y
The use o his heo y is no so common [1,6,8-10], as i assumes ha elec os a ic discha ges occu
be ween he adhe end and he adhesi e. These p o ide a s able join , which can only be
unin en ionally b oken in he e en o depola iza ion o o cible ea ing o o he su aces. As s a ed
by De jaguin e al. [10], he po en ial o he heo y is used mainly in he bonding o polyme s and
shee s, and, con a ily, in he case o o he ma e ials, he esul s o he heo y a e negligible, because
he e is no a su icien ly s ong elec os a ic cha ge be ween he su aces.
1.3. Di usion heo y
This heo y is especially applicable o polyme -based ma e ials, as i is based on he hypo hesis ha
he join s eng h can be inc eased by mu ual di usion (in e di usion) o he adhe end and he
adhesi e. Thus, he mo e simila he chemical composi ion o he adhe ends, he s onge he join
should be [1-2,6,9]. The mu ual di usion o ma e ials usually does no occu spon aneously, bu i is
necessa y o use aids. This, o example, is a usage o a p ime be o e applying he adhesi e.
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1.4. Adso p ion heo y
Cu en ly, mo e adso p ion heo ies a e used (see Table 1), bu all p esume ha he basis o adhesion
is he in e ac ion o he molecules o he adhe end and he adhesi e [4].
1.4.1. Su ace we abili y heo y. The main p e equisi e o pe ec adhesion is he c ea ion o a bond
o ces, i.e. in e ac ion o he adhe end and he adhesi e h ough mu ual con ac [6,8-9]. This p ocess is
called su ace we abili y because he adhesi e mus be able o we he en i e adhe end. The hypo hesis
o his heo y is simila o he assump ion o he mechanical heo y, whe e he adhesi e pene a es in o
all he gaps o he su ace and, a e cu ing, o ms a non-de achable join .
1.4.2. Chemical heo y. I is necessa y o he adhesi e and he adhe end o in e ac wi h each o he o
o m a i m join . This in e ac ion occu s h ough he o ma ion o p ima y chemical bonds. While
acco ding o Ebnesajjad [6], hese a e co alen , hyd ogen, Li shi z – an de Waals o ces and he
in e ac ion o acid bases, acco ding o Mi al and Pizzi [9], i can only be he ac ion o co alen bonds,
he s eng h o which is mo e han en old. Howe e , he chemical bond be ween he adhesi e and he
adhe end does no occu wi hou he exis ence o in e ac ing chemical g oups. Fo some ma e ials, he
in e ac ion occu s na u ally, some imes i is necessa y o modi y he adhe end, o example by
applying a p ime o deep imp egna ion o he su ace, o by choosing ano he , mo e e ec i e,
adhesi e. I is ob ious ha he main hypo hesis o his heo y is simila o he assump ions o he
mechanical heo y and he su ace we abili y heo y.
1.4.3. Theo y o Weak – Bounda y – Laye . The idea o his heo y was i s desc ibed by Bike man
[2-3,6-7,9] and accep s ha he ailu e o he bonded join occu s ei he due o poo cohesion o due o
poo adhesi e p ope ies o he op laye o he subs a e. This heo y is di ec ly ela ed o he su ace
we abili y and can be di ided in o h ee s ages: The i s s age occu s be o e he implemen a ion o
he bonded join . Sui able examples a e me als [6,9], in pa icula , o example, aluminium o coppe ,
which oxidize on con ac wi h ai and o m a hin laye o aluminium oxide o coppe ca bona e on
hei su ace. Al hough his laye p o ec s he su ace om con inued oxida ion, i comple ely deg ades
i s adhesi e p ope ies. Fo his eason, i is necessa y o emo e his laye be o e bonding. Ano he
ma e ial ha equi es su ace ea men a e polyme s (plas ics), he su ace ene gy o which is usually
e y low, bu can be inc eased by a sui able ea men me hod; The second s age is ela ed o he
d ying and cu ing o he adhesi e. Du ing his phase, he adhesi e is exposed o he su ounding
en i onmen , which, by i s agg essi eness, can signi ican ly a ec he p ope ies o he ma ginal
laye s o he join ; The las s age is he li e o he bonded join . Du ing i s li e, he join is exposed o
he en i onmen as well as o he e ec s o , o example, pain s, cleane s, e c., which o en educe he
s eng h and adhesion o he ma ginal laye s [9], and, a he same ime, also he e ec o wea he
condi ions is in ol ed.
2. Ma e ials and me hods
2.1. Selec ion o adhe ends
As al eady men ioned in he p e ious chap e , he s eng h and li espan o he bonded join is mainly
in luenced by he choice o a sui able adhe end ma e ial and he adhesi e sys em. Bonded subs a es
a e exposed o a ious s esses du ing hei li e, o du ing he li e o he join , which hey mus sa ely
wi hs and. Each ma e ial has speci ic p ope ies such as s eng h, elas ici y, oughness, e c. Howe e ,
o many ma e ials, hese p ope ies a e a ec ed by changes in he empe a u e o humidi y o he
en i onmen , which b ings a seconda y s ess in o he join [11]. E en hough, he bonded join is able
o signi ican ly elimina e hese s esses equen changes can cause a igue and damage [2]. Th ee
ep esen a i es o po ous ma e ials and one ep esen a i e o non-po ous ma e ials we e selec ed.
These namely include Ce is Basic (CB) cemen -bonded pa icleboa d, solid wood o La ix sibi ica
(SW), solid h ee-laye boa d panels (TLB), and wood-plas ic composi e (WPC). A he same ime,
hese a e ma e ials wi h high as well as low pola i y o he su ace ha signi ican ly a ec s he
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adhesi e p ope ies, which is sui able o he s udy o he a ea. The basic ma e ial cha ac e is ics o he
selec ed adhe ends ele an o he esea ched a ea a e lis ed in Table 2.
Table 2. O e iew o ele an ma e ial p ope ies - adhe ends.
Ma e ial cha ac e is ic/ Adhe end
CB
SW
TLB
WPC
Densi y [kg/m3]
1,275.0
640.0
850.0
1,250.0
Modulus o elas ici y [MPa]
6,800.0
7,400.0
13,800.0
5,500.0
Tensile s eng h pe pendicula o he boa d’s plain [MPa]
0.63
7.8
1.5
N/A
2.2. Selec ion o adhesi es
When choosing an adhesi e o an adhesi e sys em, i is necessa y o conside he sui abili y o a
speci ic applica ion. The choice may also be in luenced by he iscosi y, homogenei y and hickness o
he applied adhesi e laye . The selec ion o a sui able adhesi e is one o he basic p econdi ions o a
s ong and du able join [2].
The p esen ed pape is ocused on acade applica ions he e o e he use o s uc u al adhesi e is
necessa y. The e a e a numbe o adhesi es p oduced by a ious manu ac u e s ha can po en ially be
used o s uc u al açade join s. Pe haps he bes known a e silicone sealan s, which a e mos o en
used when i is necessa y o c ea e a lexible s uc u al join be ween glass and aluminium o s eel, o
be ween glass and glass [12-15]. S uc u al silicone join s a e ela i ely hick and lexible, which
allows hem o adap o di e en he mal s esses be ween glass and me al. Howe e , due o hei low
esis ance, s uc u al silicones a e no sui able o ans e ing he highe shea ing s ess equi ed o
some ypes o ma e ials, such as ce amic o composi e cladding. The e o e, polyme -based s uc u e
adhesi es a e cu en ly used in his ield. In pa icula , hese a e polyu e hanes and modi ied polyme s,
which ha e simila ensile p ope ies as silicones, bu a signi ican ly highe s esses. Fo his pu pose,
wo ep esen a i es o he polyu e hane g oup om wo di e en manu ac u e s and wo
ep esen a i es o he silyl-modi ied polyme s g oup om he same manu ac u e we e selec ed. These
a e p oduc s sui able o he implemen a ion o s uc u al join s wi h high lexibili y, which a e pa o
adhesi e sys ems. The use o a sys em cleane was necessa y o all selec ed ep esen a i es, as he
cleanliness and subsequen we abili y o he con ac su aces a e one o he basic pa ame e s ha has a
signi ican e ec on he s eng h and li e o he bonded join . I was also necessa y o use a p ime .
Selec ed ma e ial cha ac e is ics o he used sys ems a e lis ed in Table 3.
Table 3. O e iew o ele an ma e ial p ope ies - adhesi es.
Adhesi e/ Ma e ial cha ac e is ic
PU/1
PU/2
MS/1
MS/2
Densi y [kg/m3]
1,180
1,200
1,450
1,500
Tensile s eng h [MPa]
2.50
9.00
2.30
1.80
Shea s eng h [MPa]
2.00
5.50
2.00
2.25
Elonga ion a B eak [%]
c. 500
c. 600
c. 400
c. 330
2.3. Me hods
As al eady men ioned in he Adso p ion heo y sec ion, he c i ical su ace ene gy o su ace ension
a ec s he bonding po en ial o he selec ed adhe end. This p ope y is called he su ace pola i y o
subs ances. The highe he su ace ension alue, he mo e pola he su ace is. The e o e, i is sui able
o use an adhesi e wi h a lowe pola i y han he adhe end has o make he bonded join . In his case,
he con ac su ace o he adhe end will be we ed. In some cases, especially ega ding plas ics, i is
necessa y o inc ease hei pola i y by modi ying he adhe end [4]. As some selec ed manu ac u e s
ecommend a modi ica ion o he adhe end and o he s do no , an assessmen o he we abili y o he
adhe end was pe o med p io o he p oduc ion o es samples o adhesion assessmen pu poses. The
ou pu o he es me hod is o de e mine he size o he con ac angle α. I he su ace ene gy o he
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solid is g ea e han he sum o he su ace ene gy o he liquid and he solid-liquid in e acial ene gy,
he liquid sp eads o e he su ace o he solid in a con inuous laye . The smalle he con ac angle
obse ed, he be e he we abili y o he su ace [3,13,16-17]. I sp eading does no occu and a d op
o liquid assumes an equilib ium shape on he su ace o he solid, i is possible o measu e he con ac
angle and de ine he we abili y o he su ace. An assessmen o bo h unmodi ied and modi ied
su aces was pe o med, when a mechanical ea men by sandpape wi h g i size P80, which is
ecommended by he manu ac u e o he PU/1 sys em, was pe o med.
Ano he pa ame e ha signi ican ly a ec s he s eng h o he join is he selec ed geome y. A
sui able example o demons a e his s a emen is a single lap join , as i s shea s eng h is di ec ly
p opo ional o he wid h o he join . The wide he join , he g ea e he o ces i can wi hs and [8].
On he o he hand, i he leng h o he o e lap we e o inc ease, he inc ease in s eng h would no be
en i ely gua an eed, as i is no longe a di ec ly p opo ional ela ionship [2]. The e o e, i is no
app op ia e o es ima e he ailu e o ano he join design based on he esul s o one ype o geome y.
Each join should be designed and assessed o he speci ic me hod o adhesi e applica ion. Fo his
pu pose, a es me hod de ined as he so-called pull-o echnique was chosen, which is equen ly
used o he e alua ion o adhesion s eng h. The adhesi e was applied be ween he examined
adhe end and a squa e disc wi h (50 ± 0.1) mm side, he e o e, he size o he s udied a ea was app ox.
2,500 mm2. The adhesi e in he hickness o 3 mm, as ecommended by manu ac u e s, was applied o
su ace al eady ea ed wi h a p ime . The es samples we e kep in a clean en i onmen wi h ai
empe a u e (23 ± 2) °C; humidi y (50 ± 5) % and ai ci cula ion ≤ 0.2 m/s o 14 days. Subsequen ly,
es ing was pe o med on he mechanical p ess Hecke FP 10/1 in simila bounda y condi ions. The
pull-ou speed was se o (250 ± 50) N/s and a leas 6 samples ep esen one se . All samples wi h
alues ou side he ange ± 20% o he a e age we e emo ed. The analysis o a iance (one-way
ANOVA) was pe o med o e alua e he eco ded da a and o de e mine he signi icance o su ace
modi ica ion on adhesion. The alue o maximum load was used as a esponse and a signi icance le el
o p = 0.05 was conside ed.
3. Resul s and discussion
3.1. Con ac angle measu emen and su ace we abili y analysis
Many echnological p ocesses depend on how well he liquid we s he su ace o he solid. This abili y
is quan i ied by assessing he we abili y o selec ed adhe ends, o mo e p ecisely by measu ing he
con ac angle. Measu emen s a e made o be e unde s and he in e ac ions be ween he solid and he
liquid. Fo he p esen ed pu poses, he me hod o s a ic measu emen o he con ac angle o he d op
de ined in ČSN EN 828 [18] was chosen. We usually encoun e se e al deg ees o we abili y; i he
angle α ≥ 90°, he we abili y o he obse ed su ace is insu icien , o he wise he we abili y is
su icien and no addi ional su ace ea men is necessa y. Measu emen s we e pe o med on 3 es
samples o each adhe end. Dis illed wa e was used as he measu ing liquid. D ops o measu ing
liquids we e applied wi h a mic opipe e in he o m o d ops wi h a olume o 3–6 μl. In gene al, he
we ing liquid mus no eac wi h he measu ed su ace, o he wise he esul s would be signi ican ly
skewed and he e o e no usable o u he e alua ion. The a i hme ic mean, including he s anda d
de ia ion, was de e mined om he measu ed alues, see Table 4. G aphical ou pu s o he su ace
we abili y assessmen by he si ing d op echnique a e isible in Figu e 1. The measu ed alues o he
con ac angle o wood cladding, i. e. h ee-laye glued boa d and solid wood, show ha he we abili y
o hese su aces is su icien e en wi hou su ace ea men , so i can be assumed ha adhesion o
hese su aces will no be he main eason o possible p ema u e join ailu e. On he con a y, he
su aces o he cemen -bonded pa icleboa d and he wood-plas ic composi e a e poo ly we able and
hei ea men is necessa y o imp o e he adhesi e p ope ies.

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Table 4. Assessmen o we abili y o he su ace o açade cladding wi hou su ace ea men .
Adhe end
Con ac angle α [°]
We abili y assessmen [-]
CB
107.98 ± 2.38
poo ly we able su ace
SW
69.21 ± 8.76
su icien ly we able su ace
TLB
83.29 ± 6.95
su icien ly we able su ace
WPC
118.77 ± 1.27
poo ly we able su ace
Figu e 1. De e mina ion o we abili y o he adhe end wi hou su ace ea men : a) Ce is Basic; b)
WPC; c) h ee-laye glued boa d; d) solid wood.
Subsequen ly, all obse ed su aces we e mechanically ea ed wi h P80 sandpape . As can be seen
om he ou pu s in Table 5 and om he g aphical assessmen in Figu e 2, a 100% imp o emen in
we abili y was no obse ed only in case o he su ace o he wood-plas ic cladding. Mo eo e , in
combina ion wi h MS polyme s, he su ace o he cladding was i s only cleaned wi h he
ecommended cleaning agen , as he manu ac u e o he su ace oughening sys em does no di ec ly
ecommend i . This s ep was su icien only in he case o wooden adhe ends and he Ce is Basic
cladding. As in he case o he PU sys ems, he wood-plas ic su ace had o be mechanically ea ed o
imp o e he we abili y o he su ace; he me e ea men wi h a p ime was insu icien .
Table 5. Assessmen o we abili y o he su ace o açade cladding wi h su ace ea men .
Adhe end
Con ac angle α [°]
We abili y assessmen [-]
CB
33.53 ± 5.76
ideally we able su ace
SW
0
ideally we able su ace
TLB
0
ideally we able su ace
WPC
98.89 ± 1.28
insu icien ly we able su ace
Figu e 2. De e mina ion o we abili y o he adhe end a e su ace ea men : a) Ce is Basic; b)
WPC; c) h ee-laye glued boa d; d) solid wood.
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3.2. Analysis o he e ec o we abili y on su ace adhesi e p ope ies
As can be seen om he ou pu s o he p e ious subchap e . Th ee su aces wi h good we abili y and
one su ace wi h insu icien we abili y we e es ed. Al hough he su ace o he wood-plas ic
adhe end was addi ionally oughened and c eased, he hypo hesis o mechanical heo y was no ully
con i med. On he o he hand, i is a non-po ous ma e ial, he e o e he e was insu icien pene a ion
o he selec ed liquid in o all po es o he adhe end ma e ial.
In o de o assess he adhesi e p ope ies o he selec ed adhe ends, he adhesion was measu ed by
means o a ensile es . As can be seen om he g aphical compa ison in Figu e 3, he adhesi e
p ope ies o he selec ed subs a es we e in luenced no only by he mo phology o he su ace, i.e. he
deg ee o i s c easing, bu also by he compa ibili y wi h he selec ed adhesi e sys em. The measu ed
esul s hus signi ican ly suppo he hypo hesis o he elec os a ic heo y.
Figu e 3. Compa ison o adhesion o selec ed adhe ends and hei compa ibili y wi h he selec ed
moun ing sys ems: a) Ce is Basic; b) solid wood; c) WPC; d) compa ison o he de o ma ion o he
bonded join wi h espec o he moun ing sys em.
Al hough he we abili y o he WPC su ace was insu icien e en a e oughening, he adhesion
measu ed in combina ion wi h his adhe end is acco ding o he end line he mos consis en . The
adhesi e p ope ies o he adhe ends a ec no only he amoun o s ess ha he bonded join can
wi hs and, bu also he ela i e elonga ion o he join , as well as he ype o ailu e. The da a shown in
Figu e 3 a) demons a e ha he ailu e o he bonded join mos o en occu ed when a s ess o abou
0.8 MPa and a ela i e elonga ion o 30–40 % was eached. Rela i ely iden ical esul s we e ob ained
in combina ion wi h he PU/1, PU/2 and MS/2 sys ems. These sys ems a e di ec ly designed o
bonding o açade cladding and a e mo e lexible when compa ed o he MS/1 sys em. This is a ea u e
ha makes i easie o he bonded join o wi hs and changes in he join s ess caused, o example,
by olume changes in he açade cladding and he suppo ing subs uc u e. The compa ibili y o he
selec ed adhe end was also con i med by he p edominan ype o join ailu e me hod; he subs a e
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ailu e in 88 % o he measu emen s was so-called ibe - ea ailu e. The ensile s eng h o he Ce is
boa d pe pendicula o he boa d’s plain is c. 0.63 MPa, he e o e, he alue s a ed by manu ac u e
has been exceeded by mo e han 20 %.
Fu he mo e, wo ypes o açade cladding made o Sibe ian la ch, i.e. solid wood planks and a
massi e la ge- o ma h ee-laye glued boa d, we e es ed. I was conside ed ha he adhesi e
p ope ies o bo h su aces a e e y simila , and his assump ion was con i med by he esul s o he
we abili y es . The e o e, only one a ian o he wood cladding was es ed in he adhesion es –
solid wood. The adhesi e p ope ies o his subs a e a e e y good, he mos equen was he
cohesi e ailu e (obse ed in 52 % o cases), o less equen was he so-called hin-laye cohesi e
ailu e. As can be seen om he compa ison in Figu e 3 b), an a e age s ess o 1.0–1.5 MPa was
achie ed a an elonga ion o 75–110%. Al hough he maximum s ess o elonga ion decla ed by he
manu ac u e o he es ed adhesi e sys ems was no eached, i is a e y sa is ac o y assessmen o he
adhesi e p ope ies o he selec ed adhe end. The las o he es ed adhe ends was he wood-plas ic.
Un o una ely, he bondabili y o WPC is highly a ec ed by i s he moplas ic ma ix [19]. The
he moplas ic componen o he ma ix has usually a e y low su ace ene gy and bad we abili y
p ope ies [19-20]. As men ioned abo e, i was necessa y o modi y he adhe end in combina ion wi h
MS sys ems, al hough hei manu ac u e does no di ec ly ecommend i . The mechanical su ace
ea men led o an 100% imp o emen o adhesion and he alues o a e age s ess a he boa d’s
plain o MS/2 we e compa able o hose obse ed in combina ion wi h PU/2. On he con a y, no
imp o emen was obse ed in combina ion wi h MS/1. Some samples b oke e en be o e he ensile
es was s a ed. Mo eo e , he adhesi e ailu e was obse ed almos in 95 % o cases.
Figu e 4. Compa ison o he de o ma ion p ope ies o he bonded join in ela ion o he used
subs a e.
The compa ison p esen ed in Figu e 3 d) and Figu e 4, demons a es he e ec o subs a e
selec ion on adhesi e s eng h o he join and he impo ance o ma e ial compa ibili y. The be e he
adhesi e p ope ies o he adhe end, he la ge elonga ion, and join s eng h can be obse ed. The da a
eco ded in combina ion wi h Ce is Basic p o ed ha he ma e ial has good adhesi e p ope ies since
i was compa ible wi h all selec ed adhesi e sys ems, mo eo e , he limi ensile s eng h o he
ma e ial was eached. The da a obse ed wi h he WPC subs a e we e consis en , see Figu e 4,
howe e , he esul s we e highly a ec ed by poo adhesi e p ope ies o he su ace. This was
con i med by he combina ion wi h wooden subs a e. As can be seen in Figu e 3 d), he sys ems PU/2
and MS/1 eached high s eng h and smalle elonga ion be o e he join ailu e, on he con a y, he
sys ems PU/1 and MS/2 we e ex ended o mo e han 100 %. Finally, he one-way analysis o a iance
(ANOVA) was pe o med o de e mine he signi icance o adhesion heo ies in a ea o lexible bonded
s uc u al join s. The esul s o he analysis only con i med he esul s p esen ed in Figu e 3 and Figu e
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4. The adhesion o he cemen -bonded pa icleboa d was no signi ican ly a ec ed by poo adhesi e
p ope ies which was also con i med by mino di e ences in he eco ded ensile s eng h. On he
con a y, he a iance o alues measu ed wi h he wooden subs a e was la ge and less accu a e. In
some combina ions mo e han 10 samples we e es ed since he da a we e mo e inconsis en . The
ANOVA did no e i y signi ican di e ence only in combina ion wi h PU/2. Simila esul s we e
ob ained also in combina ion wi h WPC subs a e.
4. Conclusions
The p esen ed pape deals wi h he s udy o he su ace o selec ed subs a es in o de o p edic he
adhesi e p ope ies. The in luence o su ace adhesi e p ope ies on he adhesion o a bonded join
was examined in ou ypes o adhe ends, whe e wo ep esen a i es ha e almos iden ical su ace
p ope ies. Rep esen a i es wi h high su ace pola i y (SW), medium-high pola i y (Ce is Basic) and
low pola i y (WPC) we e delibe a ely selec ed. The pola i y o he su ace o subs ances is he cause
o he o ma ion o su ace ene gy which is exp essed by su ace ension. The highe he su ace
ension alue, he mo e pola he solid su ace o he liquid is. The pola i y o he su ace was e i ied
by de e mining he so-called we ing con ac angle. The we ing con ac angle is one o he ew
di ec ly measu able p ope ies o he solid/liquid/gas phase in e ace. This is he angle o he angen o
he su ace o he d op a he poin o con ac o he d op wi h he in e ace. The disad an age o he
measu emen is he ac ha i can be easily a ec ed by he inhomogenei y o he su ace, he e o e
homogeneous and cohesi e ma e ials we e chosen. A he same ime, 4 assembly sys ems we e es ed,
whe e he selec ed ep esen a i es o polyu e hanes ha e a highe pola i y han he ep esen a i es o
MS polyme s.
Based on he measu emen o he con ac angle and he de e mina ion o he we abili y o he
su ace o selec ed adhe ends, hei mechanical ea men was pe o med, which led o he
imp o emen o adhesi e p ope ies o all subs a es. While all assembly sys ems in combina ion wi h
Ce is Basic and wood cladding had a e y small incidence o adhesi e ailu e, which is a sign o
insu icien adhesi e p ope ies, adhesi e ailu e occu ed in 100 % o he pe o med es s in
combina ion wi h WPC. I is he e o e clea ha he hypo heses o he mechanical heo y a e ele an ,
bu do no lead o a signi ican imp o emen in he adhesion o he su ace o plas ics. On he con a y,
in he case o he di usion heo y, i was p o en ha he use o a p ime c ea es a laye imp o ing he
adhesi e p ope ies o he su ace and, a he same ime, modi ying he su ace ension, which
acili a es he o ma ion o a i m join . This heo y was es ed mainly in combina ion wi h he Ce is
Basic ma e ial. I s adhesi e p ope ies we e g ea ly imp o ed by mechanical su ace ea men , bu a
e y s ong join was o med using a p ime . The p oblem was again no ed in combina ion wi h WPC,
whe e he adhesi e ailu e o he join occu ed p ecisely in he mic olaye be ween he p ime and he
su ace o he subs a e. This means ha in he case o his ma e ial, he di usion heo y hypo hesis
was comple ely disp o ed. The hypo heses o he adso p ion heo y, which, o some ex en , also
includes he assump ions o he heo ies men ioned abo e, seem o be he mos undamen al o he
esea ched a ea.
Re e ences
[1] E. M. Pe ie, “Handbook o Adhesi es and Sealan s”, second ed., The McG aw-Hill Companies,
Inc., New Yo k, 2007.
[2] L. F. M. Da Sil a, A. Öchsne and R. D. Adams, “Handbook o Adhesion Technology”, i s
ed., Sp inge -Ve lag, Be lin, 2011.
[3] S. Ebnesajjad, “Adhesi es Technology Handbook”, second ed., William And ew, New Yo k,
2008.
[4] L. H. Lee, “Fundamen als o adhesion”, Plenum P ess, New Yo k, 1991.
[5] D. E. Packham, “The Mechanical Theo y o Adhesion: Changing Pe cep ions 1925 – 1991”, J.
Adhesion, ol. 39, pp. 137-144, 1992. doi.o g/10.1080/00218469208026545.