* Co esponding au ho :
Vesna Ž. Boga aj
email: [email p o ec ed]
De i us / Volume 07 - 2019 / pages 36-43
h ps://doi.o g/10.31025/2611-4135/2019.13857
© 2019 Cisa Publishe . Open access a icle unde CC BY-NC-ND license
UTILIZATION OF RECYCLED POLYPROPYLENE, CELLULOSE AND
NEWSPRINT FIBRES FOR PRODUCTION OF GREEN COMPOSITES
Vesna Ž. Boga aj 1,*, Pe e Fajs 1, Ca olina Peñal a 2, Ma ko Omahen 3, Ma jaž Čop 4 and
A i Hen onen 5
1
TECOS, Slo enian Tool and Die De elopmen Cen e, Kid iče a 25, 3000, Celje, Slo enia
2
AITIIP Cen o Tecnológico, Rome o 12, 50720, Za agoza, Spain
3
OMAPLAST, Koso elo a ces a 3, 1230, G osuplje, Slo enia
4
ADRIA Mobil, S aška ces a 50, 8000, No o Mes o, Slo enia
5
ECOPULP Finland Oy, Su iojan ie 9, 45610, Ko ia, Finland
A icle In o:
Recei ed:
01 July 2019
Re ised:
18 Sep embe 2019
Accep ed:
20 Sep embe 2019
A ailable online:
26 Sep embe 2019
Keywo ds:
Was e plas ics
Recycled polyp opylene
Newspape ib e
Reclaimed cellulose ib e
Mechanical p ope ies
The mal p ope ies
Fib e ein o ced composi es
Recycling
ABSTRACT
This wo k in es iga es he easibili y o using he ecycled polyp opylene ( PP), cel-
lulose (CF) and newsp in (NP) ib es in polyole in ein o ced composi es. Recycled
PP illed wi h 40 w .% o cellulose ( PP/CF) o newsp in ( PP/NP), wi h he addi ion
o impac modi ie (IM) and compa ibilizing agen (CA), ha e been p epa ed wi h ex-
usion mel ing and injec ion moulding. Mel ing and c ys alliza ion beha iou o plain
ma ix and composi es we e measu ed by di e en ial scanning calo ime y (DSC).
Mo phological and mechanical p ope ies we e also s udied using scanning elec on
mic oscope (SEM) and ensile es ing, espec i ely. The mal s abili y o composi es
was simila o nea PP o bo h ypes o he ille used. Though, he c ys allini y was
p og essi ely dec eased wi h he addi ion o CF o NP. The DSC u he e ealed an
occu ence o he wo dis inc mel ing ansi ions, meaning ha he examined ma e-
ials we e no based on pu e polyp opylene (PP), bu a e a he blends o high-densi y
polye hylene (HDPE) and PP, wha has been con i med also by he Fou ie ans o m
in a ed spec oscopy (FTIR). The la ges single sou ce o con amina ions in ecy-
cled PP comes om HDPE since bo h polyme s a e iden i ied by a simila densi y
and can be acciden ally mixed du ing he con en ional physical sepa a ion p ocess.
Composi es ein o ced wi h CF ha e shown be e mechanical pe o mances han
hose based on eclaimed NP ib es, wha can be a ibu ed o he ini ial ib e quali y.
Tensile s eng h o he composi es illed wi h CF and NP ib es was 36 MPa and 29
MPa, espec i ely, in dispa i y o 23 MPa measu ed o nea PP. The ib e addi ion
u he esul ed in subs an ial inc ease in Young modulus o he composi es. The ad-
di ion o CF and NP ib es lead o an imp o ed modulus o elas ici y by 16 and 47%,
espec i ely. Was e pape in he o m o eco e ed cellulose o eclaimed newsp in
ib e can hus mee all he echnical equi emen s o become an al e na i e o ino -
ganic ille s in he moplas ic composi es.
1. INTRODUCTION
One o he key p io i ies o he EU S a egy o Ci cula
Economy is an accele a ed shi o a mo e esou ce e i-
cien economic model in Eu ope, p o iding a p agma ic
and e ec i e solu ion o he g adual and limi ed deple ion
o i gin esou ces. By closing he ma e ial cycles in p o-
duc ion sec o s, his mode n economy allows Eu ope o
inc ease he esou ce p oduc i i y by up o 3 pe cen an-
nually. This would gene a e a p ima y esou ce bene i o
as much as 0.6 illion EURO pe yea by 2030 (EMF and
McKinsey, 2015) o he Eu ope’s economies. In addi ion
o he ecological and economical awa eness, he legisla-
i e ac ions adop ed along he EU membe s a es likewise
s ongly encou age he de elopmen o eusabili y and e-
cycling modelling o disca ded ma e ials, including was e
pape and plas ics.
Pape is he mos ecycled p oduc in he wo ld and Eu-
ope is he global champion in pape ecycling, exceeding
he a e o 72% (EPRC, 2017). On he o he hand, sca cely
a ound 26% o all plas ics s eams a e ecycled in Eu ope
(Shen and Wo ell, 2014). In 2016, 27.1 million onnes o
plas ic was e we e collec ed h ough o icial schemes in he
EU28+NO/CH in o de o be ein eg a ed back in o he p o-
duc ion cycles. Ou o his olume, 31.1% o plas ic was e
was ecycled, 41.6% was incine a ed, and 27.3% has been
37
V.Ž. Boga aj e al. / DETRITUS / Volume 07 - 2019 / pages 36-43
commi ed o he land ills. This yea ep esen s an impo -
an miles one, since o he i s ime, mo e plas ic was e
was ecycled han land illed (Plas icsEu ope, 2018). In ad-
di ion, he ecen Chinese “G een Fence” policy has limi ed
he expo o was e plas ics o China and his has caused
a build-up o was e ma e ials in Eu ope. The implica ions
o Eu ope’s subs an ial expo s o plas ics was e a e now
becoming clea e as he issues a ise om he G een Fence
blockade. Eu ope now needs o ind a esolu ion in o de
o allow new in es men s in plas ic was e ecycling and o
deal wi h he plas ic was e ha was in pas expo ed. The
challenge o ecycle mo e and o ully implemen he was e
hie a chy model, wi h p e en ion, euse, ecycling, eco e y
and disposal as he leas p e e able op ion, con inues and
emains as one o he mos impo an shi ags in imple-
men a ion o he EU Ci cula Economy Package (EC, 2015).
The e a e many p oduc ypes ha a e cu en ly no wide-
ly collec ed bu could be in u u e. Fo example, ad anced
so ing echnologies o PP a e now a ailable bu no ye
ully implemen ed as an ope a i e collec ion sys em is no
ye in place.
The possibili y o using he municipal solid was es in
he de elopmen o new alue-added p oduc s is an a ac-
i e en u e, especially wi h espec o he la ge quan i y
o pape and plas ic was e gene a ed daily. The h owaway
e a is behind us, and hese days we need o ocus on end-
o -se ice li e and ecycling issues o hese ma e ials.
Since he composi es a e na u ally mix u es o di e en
ma e ials, i is easonable o expec ha i would be easie
and less expensi e o u ilize he mixed was e plas ics in
hem.
I we look u he , he ecycled pape ib e can mee all
he equi emen s o eplacing he ino ganic ille s in he -
moplas ic composi es, wha has been ho oughly e iewed
in he li e a u e (Mochane e al. 2019; Ja iwala and Jain,
2019). Al hough was e pape ecycling main ains an im-
po an ole in a sus ainable en i onmen , he use o ecy-
cled/seconda y ib e o making he pape equi es special
ea men s o deinking, cleaning and e inemen . Subse-
quen was ewa e and sludge ea men s signi ican ly in-
c ease he p oduc ion cos s. On he con a y, he u iliza ion
o ecycled and eco e ed pape ib es as ein o ce s in a
composi e does no equi e ex ensi e p e- ea men s, bu
dec eases he demand o na u al esou ces, sa es ene -
gy and wa e , and educes pollu ion. The added ad an age
o hese composi es esul s om main aining ees by e-
ducing he use o i gin na u al ib es, making he p oduc s
cheape on a p ice pe weigh basis, since ille s a e o en
less expensi e han he polyme , while a he same ime
inc easing hei end pe o mances. A con inuous upg ade
o such ma e ials in e ms o mechanical, he mal and di-
mensional pe o mances has demons a ed he indus ial
applicabili y o a ious ields o applica ions, speci ically
o load-bea ing applica ions. Thanks o hei genuine ech-
nical, cos -e icien and en i onmen al ad an ages, na u-
al ib e ein o ced composi es (Sydow & Bieńczak, 2018;
Holbe y & Hous on, 2006; Kowaluk, 2017) a e lou ishing
and can no longe be conside ed me ely as an example o
“g eenwashing”.
The ul ima e goal o his esea ch is o s udy he p ope -
ies o he p oduced composi es, p epa ed o maximised
ac ional u ilisa ion o he was e pape ille s, balanced
agains he dele e ious e ec s on he ma e ial p ope ies,
while emaining po en ially an economically iable p o-
cess. All he inpu ma e ials o new composi es we e de-
i ed om municipal solid was e, i.e. eco e ed newsp in
ib es, eclaimed cellulose ib es, and ecycled was e plas-
ic polyole ines ( PP). The e ec s o a ious ille ypes, im-
pac modi ie and compa ibilizing agen on he mechanical
and he mal p ope ies o he esul ing composi es we e
e alua ed and compa ed wi h he p ope ies o plain PP.
This s udy is a pa o he LIFE CEPLAFIB p ojec
(LIFE17 ENV/SI/000119) in which eco-composi es based
on ecycled polyole ines ein o ced wi h di e en na u al
ib es and ille s, ob ained as byp oduc s om indus ial
p oduc ion plan s, a e being de eloped and in es iga ed
o i s indus ial use as a sandwich acous ic ba ie panels
in cons uc ion/building sec o , igid packaging inse ions
o indus ial packaging and in e io RV equipmen o he
ca a anning sec o .
2. EXPERIMENTAL
2.1 Ma e ials
Recycled polyp opylene ( PP) was supplied by he e-
cycling company OMAPLAST (Slo enia) wi h a mel low
index (MFI) be ween 7.0 and 10.0 g/10min, and he den-
si y o 0.910 g/cm³. Vi gin PP (Bo medTM RF830-MO),
supplied by Bo ealis (Vienna, Aus ia) and i gin HDPE
(HDI2061 Na u al), supplied by B askem IDESA, Mexico),
we e used in FTIR compa a i e analysis, se ing as he e -
e ence spec a. Cellulose (CF) and newsp in (NP) ib es
we e p o ided by Ecopulp Oy (Ko ia, Finland) a e chem-
ical bleaching and mechanical eco e ing, espec i ely, o
he ecei ed was e esidues om pulp & pape indus y. NP
and CF we e sh edded in o smalle ac ion pa icula es
and d ied in a acuum o en a 60°C o e -nigh o ensu e
ha he mois u e con en was minimal. The measu ed as-
pec a io (de ined as he a io o ib e leng h o diame e )
was 38 o NP and 58 o CF. The pe cen age o ib e addi-
i a ion was in all cases 40 w . %. Liococene PP-MA 7452
TP (CA), g a ed wi h 7 w .% o maleic anhyd ide, supplied
om Cla ian P oduk e (Deu schland) GmbH, Ge many,
was used as compa ibilize , and p opylene-based elas o-
me Vis amaxxTM 6202, supplied by HSH Chemie G oup,
Slo enia, se ed as an impac modi ie (IM). The blend
composi ion and sample designa ions used in his s udy
a e p esen ed in Table 1. The composi ion o he composi e
ma e ials has been selec ed on he basis o he p elimina y
esul s ob ained, whe e 26 di e en o mula ions has been
s udied and es ed, a ying he ype o ille s (i.e. newsp in
ib es wi h wo di e en size educ ions: NP sie ed o inal
ac ion o 2 mm and milled NP ib es, cellulose ib es and
ba ely husk ib es), ille con en s (0, 20, 30 and 40 w . %)
and he con en s o CA (0, 3 and 5 w . %) and IM (0, 3 and 5
w . %) in he inal o mula ion.
2.2 P ocessing
All he aw componen s we e p emixed in sealed
con aine s and shaken manually. The blends we e com-
V.Ž. Boga aj e al. / DETRITUS / Volume 07 - 2019 / pages 36-4338
pounded by simul aneous addi ion o all componen s in o
he Lab ech LTE 20-44 win sc ew ex ude wi h a ba el
empe a u e o 170°C a he eed sec ion and 180°C a
he die head. The sc ew o a ion speed was ixed a 200
pm. The ex uded s ands we e quenched in wa e and
pelle ized. The ex uded blends we e injec ion moulded
in o s anda d ensile specimens. P io o injec ion mould-
ing, pelle s we e d ied in a d ye (60°C o 24 hou s). A
K auss Ma ei 80/380 CX injec ion moulding machine
was used wi h ba el empe a u es o 150-180°C. The in-
jec ion-moulded specimens we e hen s o ed in desicca-
o s p io o es ing.
2.3 Cha ac e iza ion Analyses
2.3.1 Tensile Tes ing
Tensile es s using a Zwick/Roell Z005 (Zwick GmbH &
Co. KG, Ulm, Ge many) we e ca ied ou in compliance wi h
ISO 527-1-2 unde he ambien condi ions wi h a c osshead
speed o 5 mm min-1. The dis ance be ween he g ips was
se o 60 mm. The p esen ed alues o elas ici y modulus
(E ), ensile s eng h (σM), and elonga ion a b eak (εb) a e
an a e age om a leas six eplica es om each inal ma-
e ial.
2.3.2 Di e en ial Scanning Calo ime y
The mel ing and c ys alliza ion beha io o nea PP
and composi es we e s udied using a Me le -Toledo HP
DSC-1 wi h a empe a u e ange o 25-180°C, unde he
ni ogen pu ge and hea ing a e o 10°C/min. C ys alliza-
ion empe a u e (Tc), mel ing empe a u e (Tm), en halpy
o c ys alliza ion (∆Hc), and en halpy o mel ing (∆Hm) o
samples we e calcula ed. The pe cen o c ys allini y (%
Xc) was calcula ed om he Equa ion (1), whe e is he u-
sion hea o 100% c ys alline PP (equal o 207 J g-1; TA In-
s umen s) o (HD)PE (equal o 293 J g-1; Wunde lich, 1990)
and W ep esen s he mass ac ion o he polyme com-
ponen wi hin he inal composi es o mula ion.
(1)
2.3.3 Fou ie - ans o m in a ed spec oscopy
The chemical s uc u e o ecycled PP was analysed
wi h Fou ie ans o m in a ed spec oscopy. Fo he iden-
i ica ion o ecycla e composi ion, he spec a o i gin PP
and HDPE we e also eco ded o enable he compa a i e
analysis based on hei speci ic abso p ion bands. All he
samples we e p epa ed in he o m o hin ilms. The ins u-
men used was a Spec um One FTIR spec ome e (Pe -
kin Elme , USA), wo king in he a enua ed o al e lec ion
(ATR) mode on a ZnSe c ys al. The spec a we e collec ed
a a esolu ion o 4 cm− 1 o e he ange om 650 o 4000
cm− 1. In o al, 64 scans we e a e aged o each spec um.
2.3.4 Scanning Elec on Mic oscopy
Mo phology o he composi e ac u ed su aces we e
examina ed a e ensile es using low acuum JEOL 5500
LV scanning elec on mic oscope (SEM), equipped wi h Ox-
o d Inca (EDX) ene gy dispe si e spec oscopy. An ope a -
ing ol age o 20 kV and magni ica ions o 100x and 500x
we e used.
3. RESULTS AND DISCUSSION
3.1 Mechanical p ope ies
Resul s o he ensile modulus (E ), ensile s eng h (σM)
and elonga ion a b eak (εb) o plain PP and composi es
wi h wo di e en ein o cing componen s, i.e. CF and NP,
as a unc ion o CA and IM addi i a ion a e p esen ed in
Table 2. The ep esen a i e s ess-s ain cu es a e illus-
a ed in Figu e 1. In gene al, he addi ion o he ein o cing
elemen s, independly o hei o igin (CF o NP), has p o en
o be a success ul echnique o imp o ing he mechani-
cal p ope ies o he basic polyme ma ix. The alues o
he ensile modulus and s eng h ob ained o he esul ing
composi es we e subs an ially highe han ha o plain e-
cycled PP. Compa ed o he nea PP he addi ion o CF o
NP ib es lead o an imp o ed modulus o elas ici y by 16%
and 47%, espec i ely, and he alues o he ensile s eng h
o samples illed wi h CF and NP ib es was 36 MPa and
29 MPa, espec i ely, in con as o he 23 MPa measu ed
o ecycled nea PP. The elonga ion a b eak on he o he
hand was dec eased wi h he addi ion o ib es. This is go -
e ned by he ac ha composi es become mo e b i le wi h
he addi ion o laky ille s, howe e highe s eng h means
a ha de hus less de o mable ma e ial. Since polyp opyl-
ene has a hyd ophobic na u e and he cellulose based i-
b es has a hyd ophilic su ace cha ge, he usage o maleic
anhyd ide g a ed coupling agen has ce ainly con ibu ed
Xc (%) =
Sample
o mula ion
PP
[w . %]
CF
[w . %]
NP
[w . %]
CA
[w . %]
IM
[w . %]
PP 100 0 0 0 0
PP/CF 52 40 0 3 5
PP/NP 52 0 40 3 5
Sample Young Modulus
E [MPa]
Tensile S eng h
σT [MPa]
Elonga ion a
B eak εb [%]
PP 384 ± 18 23 ± 0.05 49 ± 6.00
PP/CF 447 ± 14 36 ± 0.44 11 ± 0.22
PP/NP 564 ± 68 29 ± 0.46 09 ± 1.96
TABLE 1: Sample composi ion o PP/CF and PP/NP Composi e.
TABLE 2: Mechanical p ope ies o PP and composi es wi h e-
spec o he ype o he ein o cing ille .
FIGURE 1: Compa ison o ensile s ess e sus s ain cu e o PP
and composi es illed wi h CF and NP ib es.
39
V.Ž. Boga aj e al. / DETRITUS / Volume 07 - 2019 / pages 36-43
o he ampli ied in e -phase compa ibili y, as e idenced
also by he SEM esul s, and hence he adhesion be ween
he componen s o he composi e (Yang e al. 2007; Žepič
e al. 2016).
In addi ion o he ole able in e phase compa ibili y,
a ious supplemen a y pa ame e s a e also in luencing
he mechanical pe o mances o ib e ein o ced compos-
i es, including he ib e aspec a io, ille dispe sion, pa i-
cle dimension, s ess ans e a he in e ace and mixing
empe a u es (Asho i and Nou bakhsh, 2008). To achie e
a p ope ade o be ween he elas ici y and s i ness o
he esul ing composi es, Vis amaxxTM p opylene-based
elas ome has been added o he mix u e blends in a ela-
i e high weigh pe cen a ge which appea s o deli e good
impac p ope ies (Kuma e al. 2017), bu s ill mode a e
lexibili y.
3.2 The mal p ope ies
The impac o he ype o ib e addi i a ion on he he -
mal cha ac e is ics o PP compounds can be assessed
om he esul s ob ained om DSC he mog aphs ha
a e g aphically p esen ed in Figu e 2. The c ys aliza ion
(Xc) and mel ing (Tm) beha iou was e alua ed om he
2nd hea ing scan, while he c ys alliza ion empe a u e (CT)
o he nea ecycled polyme and composi es was s udied
om he cooling scan. The esul s a e shown in Table 3.
The he mal s abili y o he composi es wi h ecycled
PP and eco e ed cellulose/newsp in ille s we e simila
o hose o nea PP. Howe e , he en halpy o usion o
he composi es p og essi ely dec eased wi h he addi ion
o cellulose and newsp in ib es, which can be a ibu ed
o he lowe con en o he polyme in inal ma e ial com-
posi ion. In ac , cellulose-based ib es does no essen ially
con ibu e o he mel ing endo he m, since his ype o ill-
e s does no p esen any ansi ions wi hin he empe a-
u e ange o DSC scan. Fu he mo e, i he ob ained alues
o he mel ing en halpies a e no malized on he basis o
pu e polyme con en o each sample, s ill a modes de-
c ease en halpy wi h he ib e con en can be obse ed o
mos cases. This e ec sugges s ha some in e ac ions
be ween cellulose/newsp in ib es and polyole in ma ix
ake place.The deg ee o c ys allini y, calcula ed using he
Eq. 1, is highe o he composi e han o he nea PP (Ta-
ble 3). This beha iou indica es ha newsp in o cellulose
ib es can induce c ys al nuclea ion o he ecycled poly-
me ma ix, which implies ha bo h o he u ilized ille s
can p obably be used as a nuclea ing agen o PP. Simila
obse a ions we e made by o he au ho s (Lopez-Machado
e al. 2000). By compa sion be ween he wo ypes o com-
posi es, a sligh ly highe c ys allini y yield is obse ed o
he PP/CF composi es as compa ed o he PP/NP. The
s onge adhesion be ween he PP ma ix and he NP i-
b es, as imposed by he su ace mo phology ea u es o
he composi es, could hinde he mo ion o he polyme
chains which a e close o he NPs. This dec ease in mo-
bili y could be an explana ion o he lowe c ys alline a io.
Wha was mo e in e es ing is ha he DSC esul s
e ealed he occu ence o he wo dis inc mel ing an-
si ions, implica ing ha he examined ma e ials a e no
based on pu e PP, bu a e a he blends o HDPE (peak
mel ing empe a u e a a ound 130°C) and PP (mel ing o
abou 165°C) (Camacho and Ka lsson, 2001). Pu e o ho-
mogeneous PP esin should yield a single mel ing e en
and he p esence o he smalle endo he mic ansi ion,
e ol ed a lowe mel ing empe a u es (130°C), indica es
FIGURE 2: DSC he mog ams o PP and composi es wi h e-
claimed CF and NP ib es du ing he cooling and he second hea -
ing scan.
1s hea ing scan 2nd hea ing scan
Con amina ion
Sample Mel . emp. Mel . emp. CT C is allini y [%] En halpy [J/g] HDPE PP
Tm1 [˚C] Tm2 [˚C] Tm1[˚C] Tm2[˚C] Tc [˚C] Xc HDPE Xc PP ∆Hm (HDPE) ∆Hm (PP) [%] [%]
PP 129 166 129 165 124.3 5.51 20.44 16.15 42.31
28 72
PP/CF 129 166 130 166 124.9 6.33 24.29 9.65 26.15
PP/NP 128 165 128 164 124.8 6.24 21.82 9.52 23.49
TABLE 3: DSC da a o nea PP and composi es wi h espec o di e en ille s du ing he i s and second hea ing scan.
V.Ž. Boga aj e al. / DETRITUS / Volume 07 - 2019 / pages 36-4340
he p esence o HDPE, which could be acciden ally mixed
wi h he PP ecycled con aine s o esins. A subs an ial
pa o public solid was e (MSW) s eams is composed
o mixed polyme s, like polye hylene (PE), polyp opylene
(PP), poly inyl chlo ide (PVC) and polye hylene e eph ha-
la e (PET), which a e among he mos common plas ics
was e, since hey a e he mos equen ly used comme cial
plas ics in ou daily li es as well as in indus ies. PP and
HDPE ha e simila densi ies and by using he con en ional
physical sepa a ion echnique (i.e. loa ing d op p ocess) is
almos impossible o sepa a e hem. The misclassi ica ion
o hese wo ypes o plas ic was e is highly p obable in he
daily was e so ing ou ine and explains he eason o he
p esence o HDPE in he PP ma ix.
Acco ding o he applica ion guide o he o iginal equip-
men manu ac u e o DSC measu ing de ices, he DSC
hea s o mel ing do no only de ec he con aminan , bu
can also de e mine i s pe cen le el in he inal esin (Sichi-
na, 2000). To make a apid quali a i e assessmen o he
polyole in blend composi ion we need o di ide he meas-
u ed mel ing en halpy o he “con aminan ” (∆Hm HDPE) wi h
he o al ∆Hm o he PP ecycla e. The es ima ed pe cen
le el o he HDPE in he inal ma e ial composi ion was, ac-
co ding o his calcula ion, equal o 30%.
3.3 Chemical Composi ion
The ATR-FTIR spec oscopy analysis was elabo a ed
as a quali a i e (aiding polyme s iden i ica ion based on
hei speci ic abso p ion bands) me hod o assessing he
chemical composi ion o he ecycla e PP. The ep esen a-
i e FTIR spec a o i gin PP and HDPE, and he spec a o
ecycled PP a e p esen ed in Figu e 3. In o de o di e en i-
a e be ween he HDPE and PP he 3000-2750 cm-1 spec al
egion has been i s ly aken in o conside a ion. This e-
quency ange is ela ed o di e en ib a ion ypes o me-
hyl g oups, whe ein he abso p ion bands be ween 2950
and 2850 cm-1 ep esen s he -CH2- asymme ic and sym-
me ic s e ching ib a ion ha ypically belongs o HDPE,
while ou supe imposed abso p ion bands in be ween
2985 cm-1 and 2810 cm-1 co espond o he asymme ic and
symme ic s e ching ib a ion o me hylene and me hyl
g oups, and a e subsc ibed o PP (Lin e al. 2015). Va ia-
ions be ween he spec a we e also obse ed in he 1475-
1350 cm-1 domain, whe e abso p ion bands co espond o
scisso ing ib a ion o he me hylene g oup (1470-1460 in
HDPE, and 1475-1440 cm-1 in PP spec um) and o symme -
ic de o ma ion o he me hyl g oup (1380-1370 cm-1 only in
PP spec um). Supplemen a y, a double wi h he maxima
a 730 and 720 cm-1, co esponds o bending and ocking
ib a ions o c ys alline and amo phous me hylene g oup,
is cha ac e is ically assigned o HDPE. The equency ang-
es o di e en unc ional g oups o PP and HDPE polyme s,
wi h assigned ib a ion ype a e summa ized in Table 4.
By compa ing he PP spec um o he e e ence spec-
a o i gin PP and HDPE i can be a gued ha he main
chemical s uc u e o he ecycla e belongs o PP and, in
lowe amoun o high densi y polye hylene (HDPE). On he
o he hand, all he cha ac e is ics peaks o PP and HDPE
can be ound also in PP spec um, con i ming he co-exis -
ence o bo h polyme ypes as o me ly specula ed by he
esul s o DSC analysis.
3.4 Mo phology Analysis
The in e ace in any ib e-ma ix composi e sys em is
esponsible o ansmi ing he load s esses om he
polyme o he ib es. This s ess ans e e iciency la ge-
ly depends on he ib e-ma ix in e ace and ib es quali y,
i.e. mo phology and mechanical cha ac e is ics (Kalia e al.
2011).
SEM images o eco e ed bleached cellulose ib es
and ecycled newsp in ib es we e aken o in es iga e
hei su ace s uc u e and a e shown in Figu e 4a and 4b,
espec i ely. The esul s illus a ed smoo h and clean su -
ace o bleached cellulose ib es, while he mechanically e-
claimed newsp in ib es indica ed oughe su ace ex u e,
signi ying he p esence o impu i ies such as hemicellu-
lose, lignin, pec in and waxy subs ances. Fu he mo e, he
a e age diame e s o he measu able newsp in ib es (36
± 10 µm) we e highe han hose o chemically bleached
cellulose ib es (30 ± 12 µm). This can be explained by he
ac ha bundles o indi idual newsp in ib es a e linked
oge he wi h lignin, which ac s like a cemen ing ma e ial
a ound he ib e s ands.
The o iginal pulping p ocess o newsp in ib es is
high yield mechanical pulping, consequen ly, he ex e nal
FIGURE 3: FTIR spec al compa ison o PP, i gin high-densi y
polye hylene and i gin polyp opylene.
Wa e numbe
(cm-1)
Func ional
g oup
Vib a ion
ype
Assigned
o
2985 - 2810 -C-H S eching PP
2950 - 2850 -CH2S eching HDPE
1475 - 1440 - CH2Bending PP
1470 - 1460 - CH2Bending HDPE
1380 - 1370 - CH3Bending PP
730 - 700 - CH2Rocking HDPE
TABLE 4: FTIR spec a analysis o PP and HDPE polyme s.

41
V.Ž. Boga aj e al. / DETRITUS / Volume 07 - 2019 / pages 36-43
su ace o ib es ends o be ich in lignin, hence o some
ex en hyd ophobic (G ege sen e al. 1995; Backs öm e
al. 1999), and wi h lowe s eng h p ope ies (Kibblewhi e,
1983). By con as , he emo al o lignin and ex ac i es
du ing he chemical bleaching will esul in a hyd ophilic
ib e su ace due o ca bohyd a es (cellulose, hemicellu-
loses) and be e s eng h compa ed o newsp in ib e.
The aim o he p esen s udy was, in e alia, o compa e
he e ec o mechanically ecycled newsp in ib es and
bleached cellulose ib es on he ul ima e mechanical p op-
e ies o he esul ing composi es. The quali y o he ib es
o hei ein o cemen po en ial, including he de eloped
su ace cha ac e is ics (Figu e 4), is he e o e closely ela -
ed o he ib e p e- ea ing p ocess.
Figu e 5 shows a compa ison o he e ec o illing he
ecycled polyp opylene ma ix wi h 40% o eclaimed cellu-
lose and newsp in ib es. We can obse e he di e ence
be ween he mo phology o he composi es, depending o
he chosen na u al ib es — longe cellulose ib es seem o
be mo e cohe en and b eak pe pendicula ly o he polyme
ma ix (Figu e 5a, b), while newsp in ib es a e i mly em-
bedded wi hin he polyme ma ix (Figu e 5c, d) sugges ing
a s ong in e acial adhesi e bond. On he ac u ed su ac-
es o he composi es, we can obse e ha some ib es a e
pulled ou om he ma ix, bu mos o hem a e s ill igh ly
linked o he ma ix. This las s a emen is ac ual o bo h
ypes o composi es and can be a ibu ed o he compa i-
bilizing agen e ec . The esul s o he mal and mechanical
analysis indica ed highe c is allini y and imp o ed ensile
s eng h o cellulose- ein o ced composi es as opposed
o ecycled newsp in ib e composi es, he e o e, he as-
sump ion ha chemically bleached ib es exp ess a highe
ein o cing po en ial can be clea ly con i med.
4. CONCLUSIONS
The p esen s udy has shown ha composi es based
on ecycled polyp opylene illed wi h na u al eclaimed
ib es ob ained om pos -consume was e, can be an in-
e es ing al e na i e o i gin polyme ma e ials modi ied
by a i icial ib es like glass o a amid. This leap o na u al
ib e ein o cemen s educes he mechanical p ope ies o
he composi es, when compa ed o glass o a amid ib es.
Ne e heless, he esul ing ma e ials show good speci ic
p ope ies due o he lowe densi y o he na u al cellu-
lose-based ib es. Mo eo e , hese ib es a e mo e lexible
and less ab asi e han glass ib es, p o ec ing he machin-
e y and allowing highe ecyclabili y a es. In he case o
adding he eco e ed newsp in ib es (wi hou special
ape u e and expensi e chemical p e- ea men ), we can
obse e highe imp o emen o ensile modulus compa ed
o cellulose ib e illed PP, which has a special bleaching
p e- ea men and a highe p ice. In ha pe spec i e he
selec ion o he newsp in ib e ein o cemen p o ides a
be e economic decision. Mo eo e , he inc ease o he
ensile s eng h and mo phological cha ac e is ics o he
composi es con i med good adhesion be ween he na u al
ib es and PP. The addi ion o ille s signi ican ly limi ed
he chain mo emen s in he polyme sys em and esul -
ed in highe s i ness and lowe ed he elonga ion a b eak
alues. I seems ha hese composi es can be p ocessed
wi h classical plas ic ans o ma ion echnologies, like in-
jec ion moulding o con en ional ex usion compounding.
The addi ion o eco e ed na u al ib es o was e plas ic
ma ices hus ende s he esul ing composi es o be ia-
ble om bo h he mechanical p ope ies and he en i on-
men al poin s o iew. Besides, hese ypes o ma e ials
may be eclaimed and ecycled o he p oduc ion o sec-
ond-gene a ion composi es, when mechanical ecycling
is applied. Th ough he men ioned ecycling me hod, he
ma e ials can be e icien ly e-p ocessed excluding he en-
e gy eco e y o disposal p ac ices, wi hou changing hei
chemical s uc u e.
AKNOWLEDGEMENTS
The esea ch leading o hese esul s has ecei ed
unding om he Eu opean LIFE P og amme unde he
sub-p og am o en i onmen and esou ce e iciency wi h
he g an ag eemen n° LIFE17 ENV/SI/000119. Special
acknowledgemen goes also o all p ojec pa ne s: AITIIP,
ITB, ECOPULP, ADRIA Mobil and OMAPLAST, and o he De-
pa men o Wood Science and Technology (Chai o Wood
Pes s, Modi ica ion and P o ec ion o Wood) om Bio ech-
nical Facul y o Uni e si y o Ljubljana o hei echnical
assis ance in FT-IR measu emen s.
FIGURE 4: SEM mic og aphs o a) chemically pulped and bleached cellulose ibe s, and b) mechanically ecycled newsp in ibe s.
V.Ž. Boga aj e al. / DETRITUS / Volume 07 - 2019 / pages 36-4342
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