ageing of polylactide and polylactide nanocomposite filaments 2008

Ageing of polylactide and polylactide nanocomposite filaments

Samuel Solarski, Manuela Ferreira*, Eric Devaux

Laboratoire de Genie et Materiaux Textiles (GEMTEX), UPRES EA2461, Ecole Nationale Superieure des Arts et Industries Textiles (ENSAIT),

BP 30329, 59056 Roubaix Cedex 01, France

Received 25 October 2007; received in revised form 6 December 2007; accepted 12 December 2007

Available online 23 December 2007

Abstract

An experimental study was carried out in order to check the influence of various parameters on the ageing of PLA filaments performed ina climatic room. Initially, two grades of PLA with different D-isomer contents were analysed. Even after several weeks of ageing, properties ofPLA filaments with less than 0.5% D-isomer content did not vary extensively. On the other hand, the mechanical and thermal properties of PLAfilaments with 4% D-isomer content underwent strong modifications. Subsequently, a selected organomodified bentonite (Bentone�104 e notedas B104) was blended with PLA and then melt-spun to study the influence of a nanofiller on the ageing of PLA filaments. Faster degradation ofPLA nanocomposite filaments was then observed.� 2008 Elsevier Ltd. All rights reserved.

Keywords: Polylactide; Nanocomposite; Melt spinning; Thermal properties; Mechanical properties; Ageing

1. Introduction

Polylactide (PLA) is a biodegradable polymer which can bespun to produce fibres [1,2]. PLA is very interesting because itcan be synthesized from renewable resources and it representsan interesting way to replace petroleum based polymer.

Nanofillers, such as clay and more particularly montmoril-lonite, are well known to modify the properties of polymerswhen they are blended even at low filler level (generally under5% in weight) [3,4]. Generally, the thermal, mechanical, flam-mability and barrier properties can be strongly improved. Thepolymer nanocomposites are interesting to develop nanocom-posite fibres with new properties. The use of a polymeric matrixto produce a nanocomposite multifilament yarn has beendescribed for the first time in 2002 by Bourbigot et al.[5].The matrix used was polyamide-6 (PA6) reinforced with Cloi-site�30B (C30B). The flammability of knitted structure madewith PA6 and PA6/C30B fibres was investigated and a strongdecrease of the heat release rate was measured. Then, somenanocomposite matrices were used to develop some new kind

of fibres: polyamide (PA) [6], poly(butylene terephthalate)(PBT) [7], poly(trimethylene terephthalate) (PTMT) [8],poly(ethylene terephthalate) (PET) [9e11], polypropylene(PP) [12,13] and polyimideamide (PIA) [14,15]. Until now,only few polymer/clay blends have been studied for productionof fibres. When clay is added, the thermal, fire and dimensionalstability properties of filaments are generally improved.

In previous work, we have studied the possibility to developpolylactide/clay nanocomposite filaments [16,17]. The firstclay used was Cloisite�30B [16]. We have shown that prob-lems in spinning occurred for PLA filled with more than2 wt% of C30B. The elongation at break strongly decreased,so filaments with low tensile properties were obtained. Forthis reason, a blend with dioctyl adipate as plasticiser(10 wt%) was prepared and the resulting sample was extrudedand successfully melt-spun drawn. The filaments obtained hadbetter elongation properties, so they could be used to produceknitted fabrics. The second clay used was Bentone�104 [17].B104 is more suitable to develop polymer layered silicatenanocomposite filaments. Unlike C30B, this clay can be addedup to 4 wt% without detrimentally affecting tensile strengthproperties of melt-spun filaments, especially when filamentsare drawn at high draw ratio. Moreover, it is not necessary

* Corresponding author. Tel.: þ33 3 20 25 64 75; fax: þ33 3 20 27 95 97.

E-mail address: [email protected] (M. Ferreira).

0141-3910/$ - see front matter � 2008 Elsevier Ltd. All rights reserved.

doi:10.1016/j.polymdegradstab.2007.12.006

Available online at www.sciencedirect.com

Polymer Degradation and Stability 93 (2008) 707e713www.elsevier.com/locate/polydegstab

to use plasticiser, which simplifies the extrusion of PLA andB104.

The hydrolysis of PLA has already been extensively studiedin different media: hydrolysis in neutral media (such as phos-phate-buffered solution, Ringer solution or water), in acidic oralkaline solutions [18]. The biodegradability of PLA and PLAorganoclay nanocomposite has also been investigated undercompost [19e21]. An increase of the rate of biodegradationof neat PLA after nanocomposites preparation was observed.Tsuji et al. [22]. have studied the influence of nano-structuredcarbon fillers (carbon nanotubes for example) and conven-tional carbon fillers such as carbon black on the enzymaticdegradation of PLA. Depending on the kind of filler, the deg-radation of PLA was modified. Carbon nanotubes enhancedthe enzymatic degradation, whereas carbon black disturbed it.

The influence of organoclay on the ageing of PLA filamentsis not yet known. The aim of this study is to investigate theageing of two grades of PLA filaments with different stereo-chemical compositions, and the influence of the incorporationof clay into the PLA matrix. The ageing of different kinds offilaments was accelerated using a climatic room. The proper-ties of the filaments were analysed using differential scanningcalorimetry (DSC), thermogravimetric analysis (TGA) andtensile testing machine.

2. Experimental

2.1. Materials

Two PLAs were used. Poly(L,L-lactide) (noted as PLAg) ecommercial name ‘‘Galastic’’ was supplied by Galactic S.A.Poly(L,L-lactide) Biomer L9000 was obtained from Biomer.The characteristics of these PLAs are described in Table 1.

An organomodified layer silicate supplied as Bentone�104(B104, supplier e ‘‘Elementis Specialties’’) in which the ex-change cation is benzyl dimethyl hydrogenated tallow ammo-nium (131 meq/100 g clay, w70% inorganic content) wasused to prepare PLA/clay hybrid nanocomposite (denoted asPLA/4 wt% B104).

2.2. Nanocomposite preparation

PLA nanocomposites to be melt-spun were prepared throughmelt-direct intercalation by using a conventional polymerextrusion process and optimized parameters. PLA pellets(Galastic) with 4 wt% B104 were blended using a co-rotatingextruder (Thermo Haake, diameter of screw¼ 16 mm, L/D¼25). The temperatures of the five zones were 140 �C/160 �C/170 �C/180 �C/190 �C. The rotation speed was maintained at

150 rpm. PLA and B104 were incorporated together in a firstfeeding zone. The extrudate was then pelletized.

2.3. Melt spinning

PLA and PLA nanocomposite were spin-drawn with thespinning device Spinboy I from Busschaert Engineering.PLA and PLA nanocomposite multifilament yarns wereobtained [17,23]. Pellets were first melted in a single screwextruder from 210 to 215 �C. Then melted PLA passes throughtwo dies consisting of 40 channels with a diameter of 400 mmto obtain a multifilament continuous yarn which was coatedwith Filapan CTC (blend of branched acid ester and branchedpolyglycol), a spin finish supplied by Boehme. Finally, themultifilament yarn was hot drawn between two rolls: thedraw ratio (DR), which is the ratio between the rotation speedsof the feeding and the draw rolls (first and second rolls, respec-tively) was 3.5. The speed of the feed roll was maintained at200 m/min, and the speed of the draw roll was 750 m/min.The temperature of the first roll was 70 �C, and the tempera-ture of the second roll was 110 �C [23].

2.4. Investigation of the dispersion of B104

The dispersion of clay in PLA/4 wt% B104 filaments wasanalysed using Wide-Angle X-ray Diffraction (WAXD) andTransmission Electron Microscopy (TEM).

2.4.1. WAXDThe morphological analysis by X-ray diffraction was per-

formed on a Siemens D5000 diffractometer using Cu Ka radi-ation (wavelength: 1.5406 A) at room temperature in the rangeof 2q¼ 1.5e30�, by step of 0.04� and scanning rate of 2�/min.

2.4.2. TEMTransmission electron micrographs were obtained with

a Philips CM100 apparatus using an accelerator voltage of100 kV. The samples were 70e80 nm thick and preparedwith a Reichert Jung Ultracut 3E, FC4E ultracryomicrotomecutting at �130 �C. Reported microphotographs represent typ-ical morphologies as observed at, at least, three various placesof, at least, three different slices.

2.5. Ageing

The ageing of PLA and PLA nanocomposite filaments wereperformed in a climatic room (Excal 2221-HA from Climats).The relative humidity and temperature were maintained at, re-spectively, 95% and 50 �C. This temperature was chosen to beunder the glass transition temperature of PLA, and to preventthe modifications of thermal properties of PLA.

2.6. Characterization of thermal properties

The thermal characteristics of PLA and PLA nanocompositefilaments were investigated using a TA instruments DSC 2920.Samples were placed in aluminium pan (about 5 mg) from 0 to

Table 1

Characteristics of PLAg and PLAb

PLAg PLAb

Mn (PLA) 74,500 200,000

D-isomer content (%) 4.3 <0.5

708 S. Solarski et al. / Polymer Degradation and Stability 93 (2008) 707e713

200 �C. The heating rate was 10 �C/min and the cooling ratewas controlled at 10 �C/min. Two heating scans were carriedout: the first one to observe the thermal properties of thefilaments, the second one to observe the thermal properties ofthe PLA itself, after the deletion of the thermo-mechanicalhistory. In order to measure the energies of melting, indiumstandard was used. All experiments were carried out usingnitrogen as purge gas.

2.7. Characterization of thermal stability of filaments

Thermogravimetric analyses (TGA) of PLA and PLA nano-composites filaments were performed using a TA 2050 Instru-ments at 10 �C/min from 20 to 600 �C under flowing air(50 ml/min). Filaments (about 10 mg) were placed in openplatinum pans. The precision on temperature measurementsis �0.5 �C.

2.8. Characterization of the tensile properties

The measurement of the tensile properties of PLA and PLAnanocomposite filaments have been carried out following thestandard NF EN ISO 5079 on a Zwick 1456 tensile testingmachine, the cell force used was 10 N. All the tests weremade at standard atmosphere (the temperature was 20� 2 �Cand the relative humidity 65� 5%). The length between theclamps was 20 mm. All the results represent an average valueof 30 tests.

3. Results and discussion

3.1. Dispersion of clay in PLA/4 wt% B104 filaments

To confirm obtaining PLA/organoclay filaments with nano-composite structure, the corresponding filaments were ana-lysed using TEM and WAXD. Fig. 1 presents the WAXDcurves of B104, PLA/4 wt% B104 (pellets and filamentswith a draw ratio of 3.5). The characteristic peak of B104, lo-cated at 4.4�, is shifted towards lower angle (2.5�) when B104is blended with PLA. The decrease of the diffraction anglemeans that PLA macromolecules insert between the silicatelayers of B104. By using the Bragg’s law, it is possible to cal-culate the d001 value, which is the interlayer space. For B104and PLA/B104 pellets, d is, respectively, 2.00 and 3.53 nm. Itrepresents an increase of the interlayer space, d001, of 1.53 nm.

So, a nanocomposite with a majority intercalated structure isobtained. On the other hand, as far as the PLA/4 wt% B104filaments are concerned, no peak is observed in the low anglearea. The disappearance of the characteristic peak suggeststhat the nanocomposite structure of the filaments is exfoliatedor disordered.

The nanocomposite structure of the PLA/4 wt% B104 fila-ments has also been observed using TEM (Fig. 2A and B).The image at low magnification shows a rather homogeneousdispersion of the silicate layers, even if some little tactoidsare still present. A lot of exfoliated layers can be observed inFig. 2B. Drawing seems to have a strong effect on the nanocom-posite structure. From an intercalated structure for PLA/4 wt%B104 pellets, it turns to exfoliated when PLA/4 wt% B104 ismelt-spun and drawn. The shear induced during the drawingwould make the separation of silicate layers easier in the fila-ments. The TEM images, which represent the cross-sections

0

200

400

600

800

1000

0 2 4 6 8 10 12 142Theta

In

te

ns

ity

(a

.u

.)

B104 (a)PLA / 4 wt% B104 pellets (b)PLA / 4 wt% B104 filaments (DR = 3.5) (c)

(a)

(b)

(c)

Fig. 1. XRD curves of B104, PLA/4 wt% B104 (pellets and filaments).

Fig. 2. TEM images of PLA/4 wt% B104 filaments. (A) and (B) represent, re-

spectively, the cross-sections at low (500 nm) and high (200 nm)

magnification.

709S. Solarski et al. / Polymer Degradation and Stability 93 (2008) 707e713

of the filaments, show rather well-defined dark lines (i.e., bor-ders of the silicate layers). An orientation of the silicate layersin the drawing direction can be assumed.

PLAg, PLAg/4 wt% B104 and PLAb filaments were storedin a climatic room at 50 �C and 95% relative humidity, in orderto accelerate the ageing. The mechanical and thermal proper-ties and the thermal stability of the yarns were finally measuredto observe the influence of the stereochemistry and the incor-poration of clay into the PLA matrix on these properties.

3.2. Thermal properties

3.2.1. Thermal properties of filamentsFig. 3 presents the degree of crystallinity of PLA and PLA

nanocomposite filaments as a function of ageing time. At initialtime, PLAg and PLAg/4 wt% B104 filaments have similar de-gree of crystallinity (around 35%). Concerning PLAb filaments,it is higher (54%). This difference is explained by the differentD-contents of PLAg and PLAb. The lower the D-content, thehigher the degree of crystallinity. The D-content of PLAb isless than 0.5%, while it is 4.3% for PLAg, so higher degreeof crystallinity can be reached with PLAb.

An increase of the degree of crystallinity can be observedfor each filament. This increase is due to the hydrolysis ofthe PLA chains, in the amorphous regions rather than in thecrystalline areas, the amorphous regions being more accessi-ble. So, the first step of the hydrolytic degradation occurs inthe amorphous areas. The remaining PLA chains then havehigher mobility. They can reorganize themselves, which leadsto an increase of the degree of crystallinity. But this increase isdifferent for each kind of filaments. The degree of crystallinityof PLAb filaments increases by only 15%, while it is 50% forPLAg filaments. So it seems that PLAb filaments, with low D-content, degrade slower than PLAg filaments. This slower deg-radation can be explained by the high degree of crystallinity ofPLAb filaments which reduces the possibility to hydrolysePLA macromolecules.

The presence of clay seems to increase the hydrolysis ofPLA. The degree of crystallinity of PLAg/4 wt% B104 fila-ments increases by 59%, while it is 50% for PLAg filaments.This faster degradation may be due to the presence of

hydroxyl groups of the silicate. These hydroxyl groups wouldpromote the hydrolysis of PLA macromolecules [21].

Fig. 4 represents the glass transition temperature of PLA andPLA nanocomposite filaments as a function of ageing time. Atfirst, an increase of Tg is observed between initial time and 7days, whatever the filaments analysed. This increase may be as-signed to an annealing effect. Tsuji et al. [24] observed the sameeffect during the in vitro hydrolysis of PLA film in phosphate-buffered solution. Then, Tg reaches a maximum value. Only Tgof PLAg/4 wt% B104 filaments decreases slightly. So, no clearconclusions can be deduced here. The high orientation of PLAmacromolecules in the filaments prevents to observe any mod-ifications of the glass transition. So, it is necessary to observethe second heating scan which represents the thermal propertiesof PLA, regardless of its thermo-mechanical history.

3.2.2. Thermal properties of PLA regardless the thermo-mechanical history

To observe the effect of ageing on the glass transitiontemperature of the different PLA, Tg was measured during thesecond heating scan. The Tg values for PLAg, PLAg/4 wt%B104 and PLAb are presented in Fig. 5. The dependence of Tgon the number-average molar mass can be expressed accordingto the equation proposed by Fox and Flory [25]:

Tg ¼ TNg � K

Mn

where K is a constant depending on the polymer and TNg is the

glass transition temperature value of the polymer with a sup-posed infinite molar mass. For PLAb, Tg remains constantaround 56 �C. So we can suppose that the variation of Mn isnot sufficient to lead to a decrease of Tg. Concerning PLAg,after an induction period until 40 days where Tg remains con-stant around 51 �C, then Tg decreases to 28.5 �C. So after 40days ageing, Tg of PLAg decreases which means that Mn

has also decreased, due to hydrolysis. It is interesting tonote that the incorporation of B104 into PLA leads to a fasterhydrolysis. In this case, there is no induction period, Tg de-creasing from the beginning of the ageing. It confirms a fasterdegradation of the PLA matrix in the presence of clay dis-persed at nanoscale level.

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70 80Time (days)

De

gre

e o

f c

ris

ta

llin

ity

(%

)

PLAgPLAg / 4 wt% B104PLAb

Fig. 3. Degree of crystallinity of PLA and PLA nanocomposite filaments as

a function of ageing time.

01020304050607080

0 10 20 30 40 50 60 70 80Time (days)

Gla

ss

tra

ns

itio

n

tem

peratu

re (°C

)

PLAgPLAg 4 wt% B104PLAb

Fig. 4. Glass transition temperature of PLA and PLA nanocomposite filaments

as a function of ageing time.


The ageing of PLAg has also strong influence on the crys-tallization process. During the second heating scan, a strongdecrease of the temperature of cold crystallization (Tcc) canbe observed for PLAg (cf. Fig. 6). At initial time, Tcc is120 �C, it falls to 88 �C after 70 days. This decrease is dueto the hydrolysis of PLA macromolecules. The chains beingshorter, their ability to crystallize increases. ConcerningPLAg/4 wt% B104, Tcc is lower at initial time (104 �C).Clays were found to display a strong influence on the crystal-lization rate of PLA, as well as on other polymers where theyplay the role of nucleating agent and promote crystallization[26e29] allows increasing the crystallinity rate. So the sili-cate layers of B104 which are delaminated can act as nucle-ating agents and promote the crystallization of the PLAmacromolecules. After 17 ageing days, there is no morecold crystallization. In fact, PLAg/4 wt% B104 fully crystal-lizes during the cooling scan. Fig. 7 which represents the en-thalpy of crystallization of PLAb and PLA/4 wt% B104 asa function of ageing time shows clearly that PLAg/4 wt%B104 fully crystallizes after 20 ageing days, and reachesa maximal value at 35 J/g. For PLAb, Tcc remains constantaround 92 �C (cf. Fig. 6).

Fig. 8 represents the enthalpy of cold crystallization (DHcc)of PLA and PLA/4 wt% nanocomposite as a function of age-ing time. Concerning PLAb and PLAg/4 wt% B104, a decrease

of DHcc is observed. This effect is due to the ability of PLAband PLAg/4 wt% B104 to crystallize during the cooling scan.Concerning PLAg, it does not crystallize during cooling, so anincrease of DHcc is observed until 40 ageing days where it rea-ches a maximum value of 34 J/g. These results confirm thefaster degradation of PLAg/4 wt% B104 compared withPLAg. But for PLAb, if there was no modification of Tg andTcc, a modification of the crystallization is observed. PLAbcrystallizes more easily during the cooling scan. It meansthat a slight hydrolysis of PLAb occurs during ageing.

3.3. Thermal stability of PLA filaments

The PLA filaments were analysed using TGA in order tocheck the release of low molecular weight compounds gener-ated during the hydrolysis. These low molecular weight com-pounds have lower thermal stability and should be degradedand/or volatilized more easily. Fig. 9 presents the TG curvesfor PLAg, PLAg/4 wt% B104 and PLAb at initial and finalageing times. Concerning PLAg, a faster thermal degradationof the resin is clearly observed after ageing. At initial time, theonset of degradation temperature at 10% weight loss (T10%) ofPLAg is 307 �C, and it falls to 244 �C after ageing. It repre-sents a decrease of 63 �C. This effect is amplified whenPLAg contains 4 wt% B104. Before ageing, the stability ofPLAg/4 wt% B104 is higher than PLAg, the silicate layers

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70 80Time (days)

Gla

ss

tra

ns

itio

n

tem

peratu

re (°C

)


Fig. 5. Glass transition temperature of PLA and PLA nanocomposite as a func-

tion of ageing time (second heating scan).

60

70

80

90

100

110

120

130

0 10 20 30 40 50 60 70 80Time (days)

Co

ld

crystallizatio

n

tem

peratu

re (°C

)

PLAg E3PLAg 4 wt% B104 E3.5PLAb E3

Fig. 6. Cold crystallization temperature of PLA and PLA nanocomposite as

a function of ageing time (second heating scan).

0

5

10

15

20

25

30

35

40

0 10 20 30 40 50 60 70 80Time (days)

En

th

alp

y o

f c

ry

sta

lliza

tio

n (J

/g

)

PLAg / 4 wt% B104PLAb

Fig. 7. Enthalpy of crystallization of PLAb and PLA/4 wt% B104 as a function

of ageing time (cooling scan).

05

10152025303540

0 10 20 30 40 50 60 70 80Time (days)

En

th

alp

y o

f c

old

cris

ta

lly

za

tio

n (J

/g

)


Fig. 8. Enthalpy of cold crystallization of PLA and PLA/4 wt% nanocomposite

as a function of ageing time (second heating scan).


acting as an insulating barrier. T10% is then 328 �C. After age-ing, the thermal stability of PLA/4 wt% B104 strongly de-creases, and T10% is only 233 �C, which representsa decrease by 95 �C. These results confirm the trend observedusing DSC. The degradation of the PLA matrix is faster in thepresence of clay dispersed at nanoscale level.

For PLAb, the thermal stability is the same before and afterageing, T10% being 311 �C. Even if PLAb undergoes a slighthydrolysis, as shown using DSC, it does not lead to the forma-tion of low molecular weight compounds with lower thermalstability than PLA.

3.4. Tensile properties of PLA filaments

In order to observe the influence of the ageing on the me-chanical properties, each kind of filaments has been tested.Fig. 10 represents the Young’s modulus values of PLAg,PLAg/4 wt% B104 and PLAb filaments. The initial Young’s

modulus values of PLAg and PLA/4 wt% B104 are similar(5.9 GPa). Then, these two kinds of filaments follow thesame trend. The Young’s modulus slightly decreases until thefilaments are too weak to be tested, that is to say from 60 age-ing days for PLAg filaments and 50 ageing days for PLAg/4wt% B104 filaments. For PLAb, it remains almost constant.Only a small decrease is observed at the end of the test. Con-cerning the tensile strength (cf. Fig. 11) of PLAg and PLAg/104, it continuously decreases. This decrease is slightlyquicker concerning PLA/4 wt% B104. For PLAb, it also de-creases, but slower. These results confirm the previous obser-vations. When PLAg is filled with 4 wt% B104, the ageingis promoted and the hydrolysis occurs faster which leads toa quicker degradation of the tensile properties of the filaments.For PLAb, the D-content being lower, the degree of crystallin-ity is higher, which limits the hydrolysis and the decrease ofthe tensile properties.

4. Conclusions

Two parameters, the stereochemistry of PLA and the incor-poration of clay, have been studied to understand their influ-ence on the ageing of PLA filaments. It was shown that theD-content played a key role in the properties of PLA filaments.The lower the D-content, the higher the degree of crystallinity.So, PLAb filaments had higher degree of crystallinity, wereless sensitive to hydrolysis and kept their tensile propertiesfor a longer time during ageing in comparison with PLAgfilaments.

The effect of the incorporation of silicate layers in PLA fil-aments has also been demonstrated. It tended to promote thehydrolysis of PLA, so it detrimentally affected the tensileproperties. This phenomenon could be explained by the pres-ence of hydroxyl groups of the silicate, which would promotethe hydrolysis of PLA macromolecules.

So these two parameters can be adjusted to modulate thelifetime of PLA filaments. For long-time applications, PLAwith low D-content should be favoured. For short time applica-tions, PLA with higher D-content and filled with organoclaycan be used.

0

20

40

60

80

100

We

ig

ht (%

)

0 100 200 300 400 500 600Temperature (°C)

––––––– – – – – ––––– · PLAg 4 wt% B104 it––– – – ––– ––– ––––– –

(1) (3)(5)

(2)

(4)

(6)

(5)

(1)(2)(3)(4)

(6)

PLAg itPLAg ft

PLAg 4 wt% B104 ftPLAb itPLAb ft

Fig. 9. TG curves for PLAg, PLAg/4 wt% B104 and PLAb at initial (noted as

it) and final (noted as ft) ageing times.

0

1

2

3

4

5

6

7

0 10 20 30 40 50 60 70 80Time (days)

Yo

un

g's

M

od

ulu

s (G

Pa

)


Fig. 10. Young’s modulus of PLA and PLA nanocomposite filaments as a func-

tion of ageing time.

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80Time (days)

Te

ns

ile

s

tre

ng

th

(M

Pa

)


Fig. 11. Tensile strength of PLA and PLA nanocomposite filaments as a func-

tion of ageing time.


Acknowledgements

This research programme is realized within the frameworkof INTERREG III France-Wallonie. The authors thank theFEDER funds (European Union), the Walloon region and theNord Pas-de-Calais region for the financial support.

References

[1] AgrawalAK,BhallaR.Advances in the productionof poly(lactic acid)fibres.

A review. J Macromol Sci Part C Polym Rev 2003;43(4):479e503.

[2] Gupta B, Revagade N, Hilborn J. Poly(lactic acid) fibre: an overview.

Prog Polym Sci 2007;32(4):455e82.[3] Alexandre M, Dubois P. Polymer layered silicate nanocomposites: prep-

aration, properties and uses of a new class of materials. Mater Sci Eng

2000;28(1e2):1e63.

[4] Sinha Ray S, Okamoto M. Polymer/layered silicate nanocomposites: a re-

view from preparation to processing. Prog Polym Sci 2003;28(11):1539e

641.

[5] Bourbigot S, Devaux E, Flambard X. Flammability of polyamide-6/clay

hybrid nanocomposite textiles. Polym Degrad Stab 2002;75(2):397e402.[6] Yoon K, Polk MB, Min BG, Schiraldi DA. Structure and property study

of nylon-6/clay nanocomposite fibre. Polym Int 2004;53(12):2072e8.

[7] Chang JH, An YU, Kim SJ, Im S. Poly(butylene terephtalate)/organoclay

nanocomposites prepared by in situ interlayer polymerization and its fi-

bre (II). Polymer 2003;44(19):5655e61.

[8] Chang JH, Kim SJ, Im S. Poly(trimethylene terephthalate) nanocompo-

site fibres by in situ intercalation polymerization: thermo-mechanical

properties and morphology (I). Polymer 2004;45(15):5171e81.

[9] Chang JH, Kim SJ, Joo YL, Im S. Poly(ethylene terephthalate) nano-

composites by in situ interlayer polymerization: the thermo-mechanical

properties and morphology of the hybrid fibres. Polymer 2004;45(3):

919e26.

[10] Chang JH, Kim SJ. Polyester nanocomposite fibres: comparison of their

properties with poly(ethylene terephthalate) and poly(trimethylene tere-

phthalate). Polym Bull 2004;52(3e4):289e96.[11] Xiao W, Yu H, Han K, Yu M. Study on PET fibre modified by nanoma-

terials: improvement of dimensional thermal stability of PET fibre by

forming PET/MMT nanocomposites. J Appl Polym Sci 2005;96(6):

2247e52.

[12] Pavlikova S, Thomann R, Reichert P, Mulhaupt R, Marcincin A,

Borsig E. Fibre spinning from poly(propylene)eorganoclay nanocompo-

site. J Appl Polym Sci 2003;89(3):604e11.[13] Zhang X, Yang M, Zhao Y, Zhang S, Dong X, Liu X, et al. Polypropyl-

ene/montmorillonite composites and their application in hybrid fibre

preparation by melt-spinning. J Appl Polym Sci 2004;92(1):552e8.

[14] Miko1ajczyk T, Olejnik M. Analysis of the structure and properties of

polyimidoamide nanocomposite fibres containing variously modified

montmorillonite. J Appl Polym Sci 2006;101(2):1103e8.

[15] Miko1ajczyk T, Rabiej S, Olejnik M, Urbaniak-Domaga1a W. Strength

properties of polyimideamide nanocomposite fibres in terms of their

porous and supermolecular structure. J Appl Polym Sci 2007;104(1):

339e44.

[16] Solarski S, Mahjoubi F, Ferreira M, Devaux E, Bachelet P, Bourbigot S,

et al. (Plasticized) polylactide/clay nanocomposite textile: thermal,

mechanical, shrinkage and fire properties. J Mater Sci 2007;42(13):

5105e17.[17] Solarski S, Mahjoubi F, Ferreira M, Devaux E, Bachelet P, Bourbigot S,

et al. Designing polylactide/clay nanocomposites for textile applications:

effect of processing conditions, spinning and characterization. J Appl

Polym Sci, in press.

[18] Tsuji H, Ikarashi K, Fukuda N. Poly(L-lactide): XII. Formation, growth,

and morphology of crystalline residues as extended-chain crystallites

through hydrolysis of poly(L-lactide) films in phosphate-buffered solu-

tion. Polym Degrad Stab 2003;84(3):515e23.[19] Sinha Ray S, Yamada K, Ogami A, Okamoto M, Ueda K. New polylac-

tide/layered silicate nanocomposite: nanoscale control over multiple

properties. Macromol Rapid Commun 2002;23(16):943e7.[20] Sinha Ray S, Yamada K, Okamoto M, Ueda K. New polylactide-layered

silicate nanocomposites. 2. Concurrent improvements of material proper-

ties, biodegradability and melt rheology. Polymer 2003;44(3):857e66.

[21] Sinha Ray S, Yamada K, Okamoto M, Ueda K. Control of biodegradabil-

ity of polylactide via nanocomposite technology. Macromol Mater Eng

2003;288(3):203e8.

[22] Tsuji H, Kawashima Y, Takikawa H, Tanaka S. Poly(L-lactide)/nano-

structured carbon composites: conductivity, thermal properties, crystalli-

zation, and biodegradation. Polymer 2007;48(14):4213e25.

[23] Solarski S, Ferreira M, Devaux E. Thermal and mechanical characteris-

tics of polylactide filaments drawn at different temperatures. J Text Inst

2007;98(3):227e36.

[24] Tsuji H, Mizuno A, Ikada Y. Properties and morphology of poly(L-lac-

tide). III. Effects of initial crystallinity on long-term in vitro hydrolysis

of high molecular weight poly(L-lactide) film in phosphate-buffered solu-

tion. J Appl Polym Sci 2000;77(7):1452e64.

[25] Fox TG, Flory PJ. Second-order transition temperatures and related prop-

erties of polystyrene. I. Influence of molecular weight. J Appl Phys

1950;21(6):581e91.[26] Pluta M, Galeski A, Alexandre M, Paul MA, Dubois P. Polylactide/mont-

morillonite nanocomposites and microcomposites prepared by melt

blending: structure and some physical properties. J Appl Polym Sci

2002;86(6):1497e506.[27] Di Y, Iannace S, Di Maio E, Nicolais L. Poly(lactic acid)/organoclay

nanocomposites: thermal, rheological properties and foam processing. J

Polym Sci Part B Polym Phys 2005;43(6):689e98.[28] Pluta M. Morphology and properties of polylactide modified by thermal

treatment, filling with layered silicates and plasticization. Polymer

2004;45(24):8239e51.

[29] Sinha Ray S, Okamoto M. Biodegradable polylactide and its nanocompo-

sites: opening a new dimension for plastics and composites. Macromol

Rapid Commun 2003;24(14):815e40.


ageing of polylactide and polylactide nanocomposite filaments 2008

Documents