Mechanical Cha ac e isa ion o Na u al Fib e Rein o ced Plas ics
P. Viei a
1
, C. Romão
2
, A.T. Ma ques
3
J.L. Es e es
3
1
INEGI – Ins i u e o Mechanical Enginee ing and Indus ial Managemen , Leça do Balio, Po ugal
2
IPV - Ins i u e Poly echnic o Viseu, Viseu, Po ugal
3
FEUP – Facul y o Enginee ing o Uni e si y o Po o, Po o, Po ugal
Keywo ds: Na u al Fib es, Sisal, Hemp, Composi e.
Abs ac
The wo k desc ibed in his pape e e s o he mechanical cha ac e isa ion o
ib e ein o ced composi e ma e ials wi h an epoxy ma ix. Sisal and Hemp ib es
a e used wi h di e en su ace ea men s.
The compa ison be ween a e e ence glass ib e ein o ced composi e and
he o he na u al ib es composi es is made. I is also p esen ed he in luence o
he su ace ea men in he mechanical cha ac e iza ions o he na u al ib es
A b ie desc ip ion o he p oduc ion o he na u al ib es composi e
ma e ials is made.
In oduc ion
Today he sea ch o new, ecyclable and enewable ma e ials is leading he
esea che s in new ways. Na u al p oduc s a e eme ging and some esea ch is
s a ing in his ma e . The wo k p esen ed he e shows he compa ison be ween
Glass, Sisal and Hemp [1-2]. Some pla es we e made using hose ma e ials as
ein o cemen and an epoxy esin as ma ix. The na u al ib es we e cleaned in
o de o emo e s aw and o he con amina ing agen s. A e hese compa isons,
we made a su ace ea men in he hemp ib es o see i i imp o es he adhesion
ib e - ma ix. The ea men used is called me ce iza ion, and is desc ibed below.
The ib e - ma ix adhesion is o he mos impo ance, and he inal esul o he
composi e is depending immensely on his ac o . The cleaning o he na u al
ib es is also e y impo an . Con amina ing agen s can also des oy he composi e
o educe i s mechanical p ope ies d as ically.
Fib e p epa a ion
Glass Ma ib e - he glass ib e is deli e ed in oles. To p epa e he ma o
in oduce in he mould, we ha e o cu i in pieces o 150x100 mm
2
. The numbe o
laye s is e y impo an , o main ain he ib e olume ac ion (30% in olume).
Na u al Sisal ib e - he i s s ep o any na u al ib e is he cleaning. When hey
we e deli e ed, hey we e ull o g ass and o he con amina ing agen s. A e he
cleaning p ocess, i was necessa y o cu he ib es in app oxima ely 30 mm leng h
pieces, o be able o agglome a e hem in he mould and make a ma . Making he
ma is he nex s ep. A e calcula ing he olume ac ion we in oduced he ib e
alea o y in he mould, close i and pu i in he p ess. A e 10 minu es we can
emo e he ma .
Na u al Hemp ib e - exac ly he same p ocess as wi h he Sisal ib es.
The nex igu es show all he p ocess.
Figu e 1: The mould Figu e 2: The na u al ib e ma
Su ace T ea men
Wi h he hemp ib es a su ace ea men has been done o inc ease he
ib e/ma ix adhesion. This ea men (me ce izing) is made in some s eps. Fi s
s ep is o pe o m an imme sion a ba h. Two hou s in a solu ion o 8% in olume
o Sodium Hyd oxide (NaOH) wi h dis illed wa e . Du ing his p ocess he ba h
was s i ed con inuously using a mechanical agi a o ( igu e 3). A he end he
solu ion p esen ed a yellow colou because o he subs ances emo ed om he
ib e. The nex s ep is cleaning he ib es se e al imes in a dis illed wa e ba h,
un il he wa e is clean. A e se e al ba hs, a neu alizing solu ion o 25% in
olume o ace ic acid is used. Again, mo e wo o h ee ba hs wi h dis illed wa e
and he ea men is inished. To d y he ib es we le hem 5 days a ambien
empe a u e, and hen six hou s a 60º C in an o en ( igu e 4). [3-5]
The su ace o na u al ib es is hyd ophilic, no gi ing good adhesion o he
hyd ophobic epoxy ma ix, so he me ce isa ion ea men y o imp o e he
adhesion ib e/ma ix by he dec ease o hyd ophilic cha ac e o he ib es.
Figu e 3: Sodium Hyd oxide ba h Figu e 4: Fib es in he o en
Manu ac u ing a pla e
To manu ac u e a pla e we used he comp ession moulding echnique. The mould
ha we can see in igu e 1 has a ca i y o 150x100x4 mm
3
and is made o
aluminium. The i s s ep is o clean he su ace and hen apply he mould elease
agen QZ13 om Ciba. A e he p epa a ion o he esin, we in oduce i in he
mould ( igu e 6). The ma is hen placed in he mould ( igu e 7) and he mould
closed. A las e e y hing is placed in he ho pla e p ess, whe e he combina ion
o p essu e and empe a u e make he pla e.
Figu e 5: Mixing he esin
Figu e 6: In oducing he esin Figu e 7: Placing he ma
A e 1 hou in he p ess, he mould has been open ( igu e 8) and he imming o
he pla e was made. Th ee examples o he pla es a e shown in igu e 9, one om
each ma e ial. In all p ocess he e we e some p oblems ha had o be sol ed. The
i s was making a homogeneous ma using he cu ed ib es. Fo 30% olume
ac ion o hemp ib e we calcula ed he need o 25 g ams. Tha amoun o ib e
be o e comp essed is in olume 5 imes bigge han he ma we need. The p oblem
wasn’ comp essing, he p oblem was main aining he olume ac ion in all he
pla e. To sol e ha p oblem, laye s we e made wi h 8 g ams each. Wi h h ee
laye s we could make a ma , and ha educes he p obabili y o ha ing a e y
di e en olume ac ion in all he pla e. Void con en is ano he p oblem.
Because o he limi a ion o his p ocess, we es ima e by measu ing he pla e and
weighing i ha he oid con en is a ound 10 %.
Figu e 8: Open mould Figu e 9: The h ee pla es
To p oduce he pla es used o he compa ison, we used he epoxy esin Reapox
520/D526 om REA Indus ies wi h he ollowing cha ac e is ics:
Tensile S eng h (MPa) = 71; Modulus (GPa) = 3.5; Densi y (g/cm
3
) = 1.12.
To p oduce he hemp pla es used o es ing he su ace ea men , we used he
epoxy esin Reapox WOOD RX8 om REA Indus ies wi h he ollowing
cha ac e is ics:
Figu e 10: Tes se up
Tensile S eng h (MPa) = 50; Modulus (GPa) = 3.0; Densi y (g/cm
3
) = 1.13.
We used a di e en esin because his new esin has wice he up u e de o ma ion
ha he i s one. We made one o wo es s wi h he 520 and he de o ma ion
wasn’ enough o he agmen a ion es s planed o make wi h his ibe s.
Mechanical Tes s and Resul s
Fo he mechanical es s we used an INSTRON 4208. We made
he es s acco ding o he ISO 527-4 s anda d. We used a 100
kN load cell and a 2 mm/min ac ion speed. Figu e 10 shows
he se up.
In ou wo k, we made he compa ison be ween glass, sisal and
hemp. In he hemp ib es we ha e also done a compa ison wi h
na u al hemp ib es and ib es subjec ed o a me ce iza ion
ea men ha is desc ibed abo e.
The esul s ( able 1) show ha he na u al ib es a e s ill e y
a om he glass ib e. I we look o he ensile s eng h, he
alue ob ained by he na u al ib es is e en in e io han he
ma ix and mo e o less ou imes smalle han he glass ib e. I we look o he
modulus, he sisal ib e composi e alue is hal o he glass ib e composi e, bu
he hemp ib e composi e is only 20 % in e io .
Composi Tensile S engh
[MPa] Modulus
[GPa] De o ma ion
[%]
REAPOX 520/D526
+
30% glass ib e
192.4 ± 20.5
10.0 ± 0.9
2.5 ± 0.3
REAPOX 520/D526
+
30% sisal ib e
50.9 ± 5.5
5.5 ± 0.5
1.3 ± 0.3
REAPOX 520/D526
+
30% hemp ib e
51.1 ± 6.8
7.8 ± 0.5
0.8 ± 0.1
REAPOX 520/D56
70
3.5
4
Table 1: Compa ison be ween he mechanical esul s o he h ee ib es
A bad ib e-ma ix adhesion could be esponsible o hese esul s. Table 2 shows
he esul s o he es s made wi h he hemp ib es. The su ace ea men made o
he ib es didn’ imp o e he adhesion be ween ib e and ma ix. In he esul s we
can see a loss o 15 % in he Tensile S eng h and a los o 30 % in he Modulus
using his ea men . In bo h cases he Tensile S eng h is in e io o he one o he
esin, bu he Modulus is highe .
When analysing he c ack, we could obse e ha he adhesion was eally bad. In
some c acks, we could see small bi es o ib e comple ely emo ed om he
ma ix. Tha shows ha he adhesion is inexis en , and ha he ib e is weakening
he ma ix ins ead o ein o cing i .
Composi e % Fib e
[%] Tensile S eng h
[MPa] Modulus
[GPa] De o ma ion
[%]
REAPOX WOOD RX8
+
Hemp wi hou ea men
25
30
35
45.6 ± 0.9
45.1 ± 6.3
47.1 ± 3.6
5.4 ± 0.4
6.2 ± 0.8
6.7 ± 0.5
0.98 ± 0.03
0.90 ± 0.22
0.81 ± 0.15
REAPOX WOOD RX8
+
Hemp wih ea men
25
30
35
37.9 ± 1.9
38.3 ± 3.9
40.7 ± 3.5
3.8 ± 0.3
4.4 ± 0.6
4.6 ± 0.3
0.69 ± 0.02
0.64 ± 0.16
0.56 ± 0.10
REAPOX WOOD RX8
50
3.0
7
Table 2: Compa ison be ween he mechanical esul s o he ea ed and he na u al ib es
Conclusions
In his s udy, in which we compa e he composi es made wi h glass, sisal and hemp
ib es, we ealize ha we can’ pick a na u al ib e, mix i wi h esin and ob ain a
composi e ma e ial. Na u al ib es a e in eali y di icul o p ocess. The esul s
ob ained a e a om good, in some cases he esul o he mechanical p ope ies
o he composi e we e in e io o he one o he ma ix.
I is necessa y o poin he esea ch in he cleaning and in he su ace ea men o
he ib e. Only wi h good su ace ea men we can ob ain a good adhesion ib e-
ma ix, and ha is one key-poin o ob ain a good composi e. In ou pape we made
he s udy using he me ce izing ea men o he ib e su ace. Tha ea men
p o ed o be inapp op ia e, because i didn’ imp o e he mechanical p ope ies,
bu ins ead i wo sened hose p ope ies. Fu u e wo ks should be made o sol e
his p oblem.
Re e ences
[1] C. Romão, “S udy o he Mechanical Beha iou o Composi e Polyme ic Ma e ials
Rein o ced wi h Na u al Fibe s", Disse a ion p esen ed o ob aining a Mas e 's
deg ee in Mechanical Enginee ing, om he Enginee ing Facul y in he Uni e si y o
Po o, Ap il, 2003.
[2] P ojec SAPIENS POCTI/40201/EME/2001, “Mechanical beha iou o Composi es o
Polyme ic Ma ix Rein o ced wi h Na u al Fibe s”, Repo o Annual P og ess, 1º
yea o ac i i y, 2002.
[3] Pe e s R.H. “Tex ile Chemis y I: The Chemis y o Fib es”, Else ie Publishing
Company, 1963.
[4] Pe e s R.H. “Tex ile Chemis y II: Impu i ies in Fib es, Pu i ica ion o Fib es”,
Else ie Publishing Company, 1967.
[5] Rowell R.M. “Chemical Modi ica ion o Ag icul u al Fibe s o P ope y enhanced
Composi es”, Cap. V, P ojec : Modi ica ion o Lignocellulosics o Ad anced
Ma e ials and New Uses, h p://www. ppl. s. ed.us, 1995.
[6] Rowell R.M., Han J.S. and Rowell J.S. “Cha ac e iza ion and Fac o s E ec ing Fibe
P ope ies”, Na u al polyme s and Ag o ibe s Composi es, pp. 115-134, 2000
[7] Eicho n S.J., Baillie C.A., Za ei opoulos N., Mwaikambo L.Y., Ansell M.P.,
Du esne A., En wis le K.M., He e a-F anco P.J., Escamilla G.C., G oom L.,
Hughes M., Hill C., Rials T.G. and Wild P.M., “Cu en In e na ional Resea ch in o
Cellulosic Fib es and Composi es”, Jou nal o Ma e ials Science, 36, pp.2107-2131,
2001.