PLASTICIZED BIONANOCOMPOSITES IN FILMS IN CONTACT WITH SKIN

M.-B. Coltelli, V. Gigante, A. Vannozzi, L. Aliotta, S. Danti, L. Panariello, A. Lazzeri

Conference ICAMP2018

University of Pisa, Department of Civil and Industrial Engineering (DICI-UNIPI)

InterUniversity Consortium of Materials Science and Technology (INSTM)

Replacing petro-based materials with renewable biodegradable counterparts is a correct strategy fortaking care of the environment, considering both sources and end of life related best practices inview of boosting the application of circular economy principles. Bioplastics play a fundamental role

On 2017 the composting was considered by EU a method of waste management identical to recycling and was defined “organic recycling”

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Personal care sector, considering monouse products in contact with body, has the possibility of much exploiting these materials

Thanks to POLYBIOSKIN project

Poly(lactic acid) (PLA)

Renewable

Compostable

Trasparent

Good processability

Advantages

PLA, yet produced on a large scale and having a cost similar to commodities, is a good

candidate for producing biodegradable films products

Excessive rigidity

Brittleness

Low crystal. rate

Disadvantages

Mature technology (about 210000 ton/year)

Cost: about 15 % more than PET

The possibility of using it in films in contact with skin in the diaper and fem pads sector, isstrongly linked to its high compatibility with body and reported slight biocidal effect (book: NPSChauhan, Biocidal polymers, 2016). Moreover it is necessary also processing it by flat dieextrusion to obtain flexible films

FLAT DIE EXTRUSION PROCESSEXTRUSION

screws

granules

Important parameters to control melt viscosity during processing :

the torque of extruder screws and the Melt Flow Rate (MFR) of

the obtained material

EXTRUDER at UNIPI FLAT DIE ACCESSORY

The possibility of using it in films in contact with skin in the diaper and fem pads sector, isstrongly linked to its high compatibility with body and reported slight biocidal effect (book:Biocidal polymers, 2016) and the possibility of processing it by flat die extrusion to obtainflexible films

Mechanical TestsThermal Analysis

Spectroscopy

Morphology

Additives Properties ApplicationsProcessing

technologiesReferences

Polymers

Increased

impact

properties,

increased strain

at break

Rigid

packaging

Flat die extrusion

(followed by

thermoforming),

injection moulding

-F. Signori, M. B. Coltelli, S. Bronco, F. Ciardelli, Polym. Degr. Stab., 2009, 94, 74–82

-MB Coltelli, C. Toncelli, F. Ciardelli, S. Bronco, Polym. Degr. Stab., 2011, 96, 982-990

-S. Farsetti, B. Cioni and A. Lazzeri, Macromol. Symp. 301, 82–89 (2011)

-V. T. Phuong, M. B. Coltelli, P. Cinelli, M. Cifelli, S. Verstichel and A. Lazzeri, Polymer 55, 4498-

4513(2014)

-V.Gigante, I.Canesi, P. Cinelli, M.B. Coltelli, A. Lazzeri, Eur. Poly. Jour., 115,125 (2019)

-M.-B. Coltelli, N. Mallegni, S Rizzo, Cinelli, Lazzeri, Materials, 2019

Plasticizers

Decreased

Modulus and

increased strain

at break

Flexible

packagingFlat die extrusion,

blow extrusion

-M-B. Coltelli, I. Della Maggiore, M. Bertoldo, S. Bronco, F. Signori, F. Ciardelli, Journal of Applied

Polymer Science, 110 (2), 1250-1262 (2008)

-M. K. Fehri, P. Cinelli, M. B. Coltelli, I. Anguillesi and A. Lazzeri, Int. Jour. Chem. Engin. Appl., 7(2), 85-

88 (2016)

-N. Mallegni, V. T. Phuong, M. B. Coltelli, M. B. Coltelli, P. Cinelli, A. Lazzeri, Materials 11(1):148, 2018

Melt strength

enhancers

Increased melt

strength

Flexible

packagingFlat die extrusion,

blow extrusion-M.-B. Coltelli, S. Bronco, C. Chinea, Polym. Degr. Stab., 2010, 95, 332-341

-A. Lazzeri, V. T. Phuong and P. Cinelli, WO2013164743 A1 (7 nov 2013)

FillersIncreased

Elastic Modulus

and tensile

strength

Rigid

packaging

Flat die extrusion

(followed by

thermoforming),

injection moulding

-A. Lazzeri and V.T. Phuong, Compos. Sci. Technol., 93, 106–113 (2014)

-V. Gigante, L. Aliotta, V.T. Phuong, M. B. Coltelli, P. Cinelli, A. Lazzeri, Composites Science and

Technology 152, 2017, DOI10.1016/j.compscitech.2017.09.008

-L. Aliotta, P. Cinelli, M. B. Coltelli, A. Lazzeri, Eur. Pol. Jour, 113,78 (2019)

Nucleating

agents

Increased

crystallinity and

elastic Modulus

Rigid

packaging Injection moulding

-X. Shi, G. Zhang, T. V. Phuong and A. Lazzeri, Molecules, 20, 1579–1593 (2015)

-M. K. Fehri, C. Mugoni, P. Cinelli, I. Anguillesi, M. B. Coltelli, S. Fiori, M. Montorsi and A. Lazzeri, Expr.

Polym. Lett. 10 (4), 274–288 (2016)

-L. Aliotta, P. Cinelli, M.B. Coltelli, M.C. Righetti, M. Gazzano, A. Lazzeri, European Polymer Journal,

DOI 10.1016/j.eurpolymj.2017.04.041, 2017

Modulation of PLA properties

The plasticization of selected polymeric blends, obtained by using biodegradable and partially biobased polyesters aswell as a citrate, is the strategy followed to obtain materials with the suitable mechanical properties and amaximized renewable content.

Not plasticized plasticized

Coltelli et al., 2008

ATBC

PBAT = poly(butylene adipate-co-terephathalate)

ATBC is more

concentrated in

the PBAT

dispersed phase

IMPORTANCE OF PLASTICIZATION FOR FULL RENEWABILITY OF BIOPOLYESTERS BASED

BIOPLASTICS

• PLA is renewable

• ATBC is renewable

• Other biodegradable polyesters (PBAT, poly(butylene succinate) –PBS-) are not fully

renewable, because currently some reagents, potentially obtainable by biorefinery

(biomass), are not yet produced on a large scale.

To obtain products with a high content of biobased raw materials, exploitable as

such in a short term perspective, it is necessary to maximize the PLA content in

the materials. As the PLA is a very rigid material, the plasticization, making it

more ductile, is necessary.

POLYBIOSKIN threshold : at least 90% renewable

The plasticization of selected polymeric blends, obtained by using biodegradable and partially biobased polyesters aswell as ATBC, is the strategy followed to obtain materials with the suitable mechanical properties and a maximizedrenewable content (> 90%)→ P1: based on PLA/PBAT;→ P2: based on PLA/PBS

P1 MD P1 CD P2 MD P2 CD

E (GPa) ≈ 0.140 ≈0.111 ≈0.080 ≈0.080

σb (MPa) 21 ± 3 16 ± 1 20 ± 6 25.1 ± 5.5

εb (%) 380 ± 30 330 ± 20 410 ± 30 423.2 ± 46.1

The use of a melt strengthening agent wasfundamental to counterbalance the decrease inmelt viscosity, mainly due to addition of the liquidplasticizer

Preparation of flexible films by flat die extrusion

BlendTorque

(Ncm)

MFR

(g/10min)

PLA + PBS + ATBC 67,8 ± 5,4 23,6 ± 2,1

PLA + PBS + ATBC + PS 72,8 ± 6,0 12,4 ± 0,9

The compatibility of the films with keratynocytes and mesenchimal stromal cells

was found very good, with a slight anti-microbial action due to the activation of

defensins

P2

Oiliness of the surface after 10 days of storage

By controlling the weight of films kept in oven at 60°C it was found that ATBC migrated significantly from thefilms making them oily on the surface

Infrared-ATR characterization

P1

P2

P1 cooled roll

0

0,5

1

1,5

2

2,5

3

3,5

0 200 400 600 800 1000 1200 1400 1600

% o

f m

as

ss

loss

Time (h)

P2

F4e

Flat die extruded films

• The tensile properties,

measured immediately after the

extrusion and after one month,

were not significantly modified

• The oiliness developed at room

temperature disappeared

comparing F4e with P2

Structure of arthropodes

exoscheletonInter-macromolecolar hydrogen bonding

Each chitin nano-crystallite is composed of about 20 linear chains of poly(N-acetyl glucosamine)

the chitin resulting rigid

substance is immersed in a

matrix of proteins and calcium

carbonate

structure

nano-assembly

Interestingly, the microfibers form layers producing a plywood-like structure

On each layer a different orientation of the microfibers is achieved, thus making the material highly resistant.

The microfibers contain crystalline nano-fibers. It is possible

to produce chitin nano-whiskers by chemical treatment of

microfibers. MAVI SUD plant, Aprilia, (Italy) patented this

process. Nano-chitin is thus available in diluted water

suspension for cosmetic applications.

Dispersing chitin nanofibrils in PLA

0 1 2 3 4 5 6 7

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

micro-carbonate

nano-carbonate

% w

eig

ht lo

ss

% by weight of additive

Bionanocomposites: Preparation of plasticized PLA/PBS films containing chitin nanofibrils

Composition Torque (Ncm) MFR (g/10min)

PLA + PBS + ATBC 67,8 ± 5,4 23,6 ± 2,1

PLA + PBS + ATBC +PS 72,8 ± 6,0 12,4 ± 0,9

PLA + PBS + ATBC +NC 60,0 ± 4,1 18,4 ± 1,3

PLA + PBS + ATBC +NC +PS 63,3 ± 3,6 13,1 ± 1,3

Chitin nanofibrils could be potentially used to decrease

ATBC mass loss

Preparation of a nano-structured pre-composite

t= 60 days

Kinetic of plasticizer loss at 60°C

0

0,5

1

1,5

2

2,5

3

0 200 400 600 800 1000 1200 1400 1600 1800

% w

eig

ht

los

s

time (h)

F1

F2

F3

F4

F8

F14

Micro-calcium carbonate 7%

Chitin nanofibrils

Plastistrength

The lowest % of lost

mass with respect to the

weight of the film is

achieved by using micro-

calcium carbonate.

The kinetic of migration

can be better studied by

considering proper

models

Conclusions

Replacing petro-based plastics with biobased and biodegradable plastics like PLA would be positive to

develop evironmentally friendly products

For obtaining flexible films with suitable properties and compatible with skin the plasticization of PLA

with biobased liquid citrates and the blending with biodegradable polyesters is necessary to reach a

high content of renewable sources in the material

Moreover, the addition of calcium carbonate and other bionanofillers like chitin nanofibrils was

fundamental to modulate surficial properties of films. Interestingly the tendency of films to slowly partially

release plasticizer, negatively affecting surficial stickiness of films, can be prevented using inorganic

fillers.

The weight of released plasticizer by using micro-calcium carbonate is strongly limited. On the other

hand CN were demonstrated to act much onto kinetic of release, making it slower. These interesting

findings can be exploited for peculiar applications.

Acknowledgements

POLYBIOSKIN European project (GA N° 745839) is kindly acknowledged

Multifunctional Bio-

Ecocompatible Materials

lab (MBEM)

Pisa, Luminaria 2015

Thank you for your

attention