Environmentally Degradable Bio-Based Polymeric Blends and Composites

Environmentally Degradable Bio-Based Polymeric

Blends and Composites

Emo Chiellini,*1 Patrizia Cinelli,1 Federica Chiellini,1 Syed H. Imam2

1UdR Consortium INSTM, Department of Chemistry & Industrial Chemistry, University of Pisa, Via Risorgimento 35,56126 Pisa, ItalyFax: þ39-050-28438; E-mail: [email protected]

2Bioproduct Chemistry & Engineering Research, USDA, ARS, WRRC, Albany, CA 94710, USA

Received: December 11, 2003; Revised: February 4, 2004; Accepted: February 4, 2004; DOI: 10.1002/mabi.200300126

Keywords: biodegradable; composites; natural fibres; poly(vinyl alcohol)

1. Introduction

In the last decades, environmental protection has become a

global concern providing much needed impetus for the

development of alternative utilization of our natural

resources. Currently, it is at the level of only 3.5% of the

overall annual production estimated around 170 billion tons

for food and non food consumption, which is quite

comparable to the annual consumption of the fossil fuel

feedstock (7.3 billion tons). However, about 93% of these

last resources are used for energy production alone with

consequent negative impact on green house gas emission

balance, eventually leading to increase in the global

warming and associated climate changes.[1] In this respect,

efforts are underway world-wide to utilize renewable

feedstock both as energy source[2] and as raw materials

for the production of chemicals and polymeric materials

and/or plastics.[3,4]

The term ‘‘bio-based polymers’’ comprises polymeric

materials obtained from renewable resources that can be

processed to engineer plastic-like products of desired struc-

tural and functional properties for applications. Several

Summary: Blends and composites based on environmen-tally degradable-ecocompatible synthetic and natural poly-meric materials and fillers of natural origin have beenprepared and processed under different conditions. Poly(vinyl alcohol) (PVA) was used as the synthetic polymer ofchoice by virtue of its capability to be processed from watersolution or suspension as well as from the melt by blowextrusion and injection molding. Starch and gelatin weretaken as the polymeric materials from renewable resources.The fillers were all of natural origin, as waste from food andagro-industry consisted of sugar cane bagasse (SCB), wheatflour (WF), orange peels (OR), apple peels (AP), corn fibres(CF), saw dust (SD) and wheat straw (WS). All the natural orhybrid formulations were intended to be utilized for theproduction of:

a) Environmentally degradable mulching films (hydro-

biomulching) displaying, in some cases, self-fertiliz-

ing characteristics by in situ spraying of water

solutions or suspensions;

b) Laminates and containers to be used in agriculture and

food packaging by compression and injection molding

followed by baking.

Some typical prototype items have been prepared

and characterized in relation to their morphological

and mechanical properties and tested with different

methodology for their propensity to environmental

degradation and biodegradation as ultimate stage of

theirservice life. A relationship between chemical com-

position and mechanical properties and propensity to

biodegradation has been discussed in a few representative

cases.

Soil appearance at the end of the hydro-biomulching fieldtrial.

Macromol. Biosci. 2004, 4, 218–231 DOI: 10.1002/mabi.200300126 � 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

218 Feature Article

major options for the production of consumer as well as

high performance industrial grade plastic products from

bio-based polymers are outlined in Figure 1. As an added

advantage, products manufactured from bio-based poly-

meric materials will eventually be biodegraded after their

useful service life is over.

A wide variety of bio-based polymers are available in

nature, which include polysaccharides such as cellulose,

starch, chitosan, proteins like wool, silk and gelatins, oils

and fats, lignin, polynucleotides, polyisoprenoids, as well

as polymers derived from monomeric components obtain-

ed from renewable resources. Moreover, polymers from

renewable resources may be broadly classified according to

the source from which they are deriving. Natural polymers

or biopolymers are synthesized in nature by living organism

and by plants through sophisticated biosynthetic pathways

requiring carbon dioxide consumption, and are ultimately

degraded and recycled in order to maintain and encourage

sustainability of resources.[5] Some natural polymers such

as rubber, lignin and humus display a slow rate of bio-

degradation, since they are produced in nature there is no

major concern for their environmental impact as ultimately

they are going to be mineralized. This concept if applied

to synthetic and semi-synthetic polymeric materials and

eventually to their hybrid composites may open new valu-

able scenarios in the production of environmentally viable

plastic items. Another category of biopolymers include

Emo Chiellini is since 1980 Full Professor of Chemical Fundaments of Technologies at the Faculty ofEngineering of the University of Pisa. In 1963 he graduated at the University of Pisa with a thesis onPolymer Science in the group of Prof. Piero Pino. Since then he continued his activity in PolymerScience & Technology at the Department of Chemistry & Industrial Chemistry of the University of Pisaand as a visiting scientist at the University of Liverpool (UK), University of Massachusetts at Amherst(USA) and University of Nagasaki (Japan). He is presently head of an interdisciplinary research groupactive in Polymer Science & Technology with specific interest in the field of Biodegradable PolymericMaterials for Biomedical, Pharmaceutical and Environmental Applications. He has served as memberof the Editorial Boards of various scientific journals related to Polymer Science & Technology, in-cluding among the others Reactive Polymers, Macromolecules, Korea Polymer Journal, Biomacromo-lecules, Polymer Degradation & Stability, Journal of Bioactive Polymers, Journal of Polymers andEnvironment. He has chaired international conferences related to Polymers in Medicine, LiquidCrystalline Polymers, Biodegradable Polymeric Materials and Plastics and a Gordon ResearchConference on Biodegradable Polymers in 1996. He is author and co-author of 400 publications inpeer-reviewed journals, 20 books and 20 patents. The research group leaded by Prof. Chiellini is activein multipartner projects funded by Industries, Italian Ministry of University & Research, and EuropeanCommunity. He is currently acting as advisor in a research program on Sustainable PolymericMaterials and Environmentally Degradable Polymers launched by the International Centre for Science& High Technology under the UNIDO sponsorship.

Patrizia Cinelli received the Laurea Degree in 1995 in Chemistry at the University of Florence bydefending a Laurea thesis under the supervision of Prof. Dante Gatteschi. In 1996 she attended the‘‘Specialization School in Materials Science and Technology’’ at the University of Genoa, Italy. In 1999she obtained the Doctor Degree in Chemistry at the University of Pisa (Italy) by defending a thesison ‘‘Formulation and Characterization of Environmentally Compatible Polymeric Materials forAgriculture Applications’’, under the supervision of Prof. Emo Chiellini and external supervision ofDr. S. H. Imam (USDA – Peoria, IL – USA). She is co-author of 30 papers in peer-reviewed journals,books and two patent applications. She is currently working as a postdoc in the research group ofProf. Chiellini in the field of polymeric materials for environmental applications and had theopportunity of performing part of the activity in the research group of Dr. Imam at the Laboratories ofthe United States Department of Agriculture (USDA), Peoria, Illinois – USA. She is actively parti-cipating in a multipartner project funded by European Commission and Industries, related to environ-mental and ecopackaging issues.

Figure 1. Major options for the production of environmentallydegradable bio-based polymeric materials and plastics.

Environmentally Degradable Bio-Based Polymeric Blends and Composites 219

Macromol. Biosci. 2004, 4, 218–231 www.mbs-journal.de � 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

‘‘artificial polymers’’ such as cellulose esters and ethers

obtained by chemical modification of naturally occurring

polymers as well as polylactate obtained from starch

bio-derived lactic acid. Other polymeric materials such

as bacterial polysaccharides, as well as array of polyesters

[poly(hydroxy alkanoates)] produced by the native as well

as genetically transformed microorganisms have only been

marginally assessed for their potential, and continue to be

the major focus of several laboratories around the world.

Important contributions to the development of the field of

polymeric materials from renewable resources may indeed

come from our knowledge of polymer assembly at the

molecular level and complete understanding biosynthetic

pathways that are critical in imparting chemical and biol-

ogical functionalities in a biological polymer. These tools

may impede our efforts in identification, isolation andmodi-

fication of potentially valuable candidates, which could be

transformed into higher-yielding production systems with

tailored polymeric structures.

The bio-based polymeric materials are relatively in-

expensive, ecocompatible, and designed to experience

environmental degradation. Particularly, fibrous material

derived from renewable crops, by-products or their indus-

trially processed wastes can be considered a good polymer

source in formulations for preparing blends and com-

posites in conjunction with either synthetic (hybrids) or

natural components that we name ‘‘natcos’’ for quick

identification.[6]

Poly(vinyl alcohol) (PVA) is a particularly well suited

synthetic polymer for the formulation of blendswith natural

polymers since it is highly polar and can also be mani-

pulated in water solutions and depending upon its specific

grade in functional organic solvents as well as processed

from the melt.[7–9] Ongoing investigation in our labora-

tories on the formulation and applicability of mixtures of

PVA, as synthetic water soluble polymeric material, and

bio-based ‘‘fillers’’ from low-value agro-industrial waste,

has highlighted the potential of attaining ecocompatible

articles meant to experience environmental degradation

at the end of their service life that eventually can be

programmed.

Ongoing research cooperation between USDA and Uni-

versity of Pisa, Italy has led to the development of several

blends and composites based on PVA and lignocellulosic

Federica Chiellini received the Laurea Degree in 1994 in Biology at the University of Pisa. In 1995 shejoined the Biochemistry Group at the University of Gent (Belgium) as a Human Capital & MobilityFellow. In 1996 she was appointed as a fellow at the Materials Science and Technology InteruniversityConsortium (INSTM) in the framework of a Brite-Euram European Project on ‘‘Bioerodible-Biodegradable Polymeric Matrices for Targeted Protein Drug Release’’. In 1997 she was appointed asa PhD student in Biomaterials at the University of Trento and in year 2001 defended a Thesis onthe ‘‘Synthesis and Chemical Biological Characterization of New Polymeric Materials Designed forTissue Engineering Applications’’. In 2000 she was a visiting scientist at Cornell University (USA) atthe Materials Science an Engineering Department and at the School of Chemical Engineering. Since2001 she works at the University of Pisa as post-doc/research associate. She is responsible for the cellculture facility at the Laboratory of Polymeric Materials, Department of Chemistry & IndustrialChemistry. Her main research interests are the design and biological characterization of bioerodible/biodegradable polymers for biomedical and environmental applications. She is co-author of over 25publications in international journals and books and she is co-inventor of two patents.

Syed H. Imam, a senior Research Chemist in the Bioproduct Chemistry & Engineering Research Unit atthe USDA-WRRC in Albany, CA is internationally recognized for his accomplishments in the area ofbiodegradable plastics, which include polymer blending, characterization, aging/performance, as wellas biodegradation. He has served on the American Society for Testing Materials (ASTM) – D20Committee on ‘‘Biodegradable Polymers’’ and currently serving on the Editorial Advisory Board of theJournal of Polymers and the Environment. Dr. Imam has served as a United Nations DevelopmentProgram (UNDP) consultant/mission advisor and has been invited to the joint International Center forScience – United Nations Industrial Development Organization (ICS/UNIDO) Expert Group Meetingson Biodegradable Polymers in Bratislava (Slovakia), Trieste (Italy) and Jakarta (Indonesia). Haspublished over 100 research articles, reviews and book chapters, and served as a chief editor of ACSBook titled ‘‘Biopolymers: Utilizing Nature’s Advanced Materials’’ published by the Oxford UniversityPress in 1999. He has served as thesis advisor for numerous graduate students from numerousinternational institutions and is the co-organizer and Program Director of the ARS-MexicoInternational Workshops on ‘‘Agriculture and Biotechnology’’ held biannually at Universidad Auto-noma de Nuevo Leon, Monterrey, Mexico. Additionally, he has organized international meetings,numerous symposiums at national and international meetings and served on the international scientificadvisory committees of international congresses. In the year 2000, Dr. Imam’s joint research withcollaborators from Italy and Egypt was nominated for the Germany’s prestigious ‘‘Braunsweig Prize’’in the field of agriculture.

220 E. Chiellini, P. Cinelli, F. Chiellini, S. H. Imam


components derived from agro-industrial waste derived

from sugar cane, citrus fruits, corn, wheat and wood

processing.[10,11]

In the present contribution, a review is provided to

capture the highlights of the current status of the field based

on our joint research of the past few years. Particularly,

efforts on developing formulations for blends and compo-

sites (both hybrid and natcos systems) along with proces-

sing parameters, resulting properties and potential

applications are described.

2. Hybrid Polymer Composites forHydro-Biomulching Practice

2.1 Formulations Based on Poly(vinyl alcohol)(PVA) and Different Agro-Industrial Wastes

In the past mulch practice has been performed by the use of

natural materials such as straw and leaves to provide an

insulating layer around the roots of vegetables and soft

fruits. Actually the use of plastic sheets or films inmulching

is the largest single application of plastics in agriculture.

Mulch controls radiation, soil temperature and humidity,

weed growth, insect infestation, soil compaction, and the

degree of carbon dioxide retention. A mulching effect or

a conditioning effect on soil structure can also be obtained

by the technique referred to as ‘‘hydro-biomulching’’ or

‘‘liquid mulching’’.[12] Due to their water solubility some

synthetic degradable polymers such as poly(acrylamide),

poly(vinyl alcohol), carboxymethyl cellulose, and hydro-

lyzed starch-g-polyacrylonitrile (HSPAN), can be easily

sprayed on the soil aloneor inmixturewith nutrients or other

mulching materials, basically indicated as ‘‘fillers’’.[13–16]

Tackyfiers helping to hold the mulch in place once applied

or aimed at forming a sort of thatch intended to protect seeds

and soil against erosion, constitute essential smart filler

ingredients. As a part of a research program aimed at the

preparation through the conventional processing technolo-

gies (casting from solution, melt blow extrusion, and

injection-compression molding) and evaluation of envir-

onmentally degradable polymers for various applications in

agricultural practices, with specific reference to the in situ

formulation of self-fertilizing mulching films, we started to

consider the possibility of utilizing poly(vinylacohol)

(PVA) and fillers from renewable resources such as wheat

straw, saw dust and sugar cane bagasse- the lignocellulosic

residue deriving from sugar cane juice extraction.[17–20]

PVA grade 8/88 Mowiol, 88% hydrolysis degree, Mn

67 000 D, was used for hydro-biomulching formulations.

Sugarcane bagasse (SCB) (Brasil) was in a powder form

(f< 0.212 mm), constituted by: 42.6% crude fibres, 29.2%

cellulose, 10.5% lignin, 9.1% crude protein, 2.6% fat, 6.0%

ash.Wheat flour (WF) was awhite thin powder (Italy), with

composition: 45.4% starch, 2.0% ash, 2.2% cellulose,

34.8% hard fibre, and 15.5% moisture. Wheat straw (WS)

was coarsely milled to an average size of 20 mm. Saw dust

(SD) was a commercial daily product from soft wood

sawing.

In a field trial carried out at the University of Pisa

between June and September, two conventional mulching

materials: polyethylene film (PE) (70 g �m�2) and wheat

straw mulching (SM) (100 g �m�2) were compared with

PVA based innovative hydro-biomulching formulations.

Data relevant to the indicated experiment set are col-

lected in Table 1.

PVA/SCB and PVA/WF water suspensions were sprayed

on the soil by an air compressor, working at 3 bar pressure

and equipped with a 2.5 mm nozzle. Saw dust and wheat

straw were directly spread on the soil (500 g �m�2) prior to

the spray application of the PVA solution. The PE film and

the SMmulching were kept in place by nails and by net and

nails, respectively.

Corn (Zea mays) and lettuce (Lactuca sativa) were chosen

to test the agronomic effect of the mulching treatments on a

seeded and a transplanted crop respectively. For each plot

three corn plantswere established by sowing and three plants

of lettuce were established by seedling transplanting.

The height and dry biomass of the growing corn plant

were measured on the days 30 and 60 of the experiment.

Sixty days after sowing, the total leaf surface area of corn

harvested plants was also determined.[21] All the lettuce

plants were harvested fifty days after transplanting and dry

biomass was measured and reported as average plant

biomass. Results relevant to the different trials are collected

in Table 2.

In thirty days, corn height and biomass production in SM

and PE values were significantly higher compared to the

control. The differences were more notable after sixty days

of sowing. While the SM behaved similar to control, the

fluid mulching performed better than the untreated soil and

with efficiency similar to that of the PE.

Compared to corn, lettuce showed different effects of

the mulching treatments. The effect of SM did not show a

statistically significant difference from the control. While

the PE promoted a growth significantly higher than the

control, surprisingly, the investigated hydro-biomulching

treatments used in our experiments exhibited much higher

biomass production.

Table 1. Hybrid composite formulations based on PVA andlignocellulosic fillers. SCB¼ Sugar Cane Bagasse, WF¼WheatFlour, WS¼Wheat Straw (milled), SD¼ Saw Dust.

Treatment PVA Organic Filler Water

g �m�2 Type g �m�2 g �m�2

SCB 20 SCB 40 340WF 20 WF 40 340WS 20 WS 500 380SD 20 SD 500 380



Remarkable differences were observed in the soil struc-

ture at the end of the experiment. Figure 2 shows the soil

surface at the end of the trial in plots that had been treated

with PVA/SCB, PVA/WF and the control (no mulching

treatment).

Soil aggregates (1–2 cm)were still present in treated soil,

but were completely absent in the control plot. SCB pre-

sence conferred a dark brown colour to the soil and further

research is warranted to explore their potential as a heat

absorbent or as a UV blocker. Moreover, the data indicated

that SCB and WF presence enhanced PVA time of per-

manence on the soil thus guaranteeing for the resulting soil

structuring effect.

2.2 Hybrid Films Based on Gelatin,Poly(vinyl alcohol) and Agro-Industrial Waste

Among naturally occurring polymers, gelatin offers good

processability properties both in aqueous media and in the

melt. It exhibits also good film forming properties, and

adheres well to a variety of substrates.[22] Gelatin is a high

molecular weight polypeptides produced by denaturation

and/or physical-chemical degradation of collagen, which

is the primary protein component of animal connective

tissues, such as bone, skin, and tendons.[23] The use of

gelatin scraps, and byproducts from pharmaceutical, agri-

cultural and tannery industries constitute an abundant

source of gelatin protein. Development of applications for

the use of such low-value, natural and biodegradable raw

material will add value to farm byproducts. We developed

formulationswherewaste gelatin scraps (WG)were provid-

ed by a pharmaceutical company (Rp Scherer, Egypt). WG

scraps were used as received and contained several addi-

tives from original formulation as pigments and glycerol.[9]

After dissolution in water, WG samples were added to

sugarcane bagasse to formulate protein-cellulose disper-

sions. This technology is particularly useful for adaptation

in countries where gelatin source and sugarcane bagasse

Table 2. Results of mulching experiments carried out on corn and lettuce growing in field trials. SCB¼ Sugar Cane Bagasse,WF¼Wheat Flour, WS¼Wheat Straw (milled), SD¼ Saw Dust, SM¼ Straw Mulch, PE¼ Polyethylene.

Mulching type Zea mays Lactuca sativa

Plant height 30 daysa) Dry biomass 30 daysa) Dry biomass 60 daysa) Total leaf area 60 daysb) Dry biomass 50 daysb)

cm g per plant g per plant m2 per plant g per plant

SCB 17.9 0.4 70.7 0.25 15.9WF 17.6 0.5 55.3 0.20 15.9WS 19.0 0.5 58.2 0.18 20.1SD 17.9 0.8 70.3 0.26 17.9SM 22.4 1.0 47.8 0.18 11.4PE 23.1 0.9 91.4 0.27 14.3Control 14.1 0.5 31.8 0.12 8.2

a) After sowing.b) After transplanting.

Figure 2. Soil appearance at the end of the hydro-biomulching field trial.



are available as raw materials to produce low cost, in-situ

formulations of environmentally degradable hydro-bio-

mulching. A series of experiments was performed by

spraying gelatin based water dispersions on pots, contain-

ing loamy soil, with an overall surface area of 154 cm2.

The compositions of film formulations sprayed on the

loamy soil are indicated in Table 3. The pots were left

outdoors under open-air along with control, which did not

receive any treatment.

Films were obtained by the direct spraying technique

on soil with the aim of testing the feasibility of a single

pot application in field experiments. The evolution of

film morphology formed on loamy soils was monitored for

three weeks.

The results of sprayed film experiments showed that the

films lasted for more than two weeks on the soil and the

soil appeared to be conditioned and in a better state when

compared with the control sample. It is worth mentioning

that, during the experiment time the boots containing the

sprayed films were exposed to outdoor conditions that were

monitored for all the duration of the experiment.[24]

3. Bio-Based Polymeric Blends andComposites – Processingand Mechanical Characterization

3.1 Hybrid Films by Casting from WaterSolution or Dispersion

3.1.1 Films based on waste gelatin (WG), poly(vinylalcohol) (PVA) and sugar cane bagasse (SCB)

WasteGelatin (WG) based filmswere cast from solutions or

dispersions containing WG and either PVA or SCB com-

ponents by slow evaporation of the water at room tem-

perature and at atmospheric pressure.[9] Low molar mass

dialdehydes and high molecular weight dialdehydes are

the most popular crosslinking reagents, especially for pro-

tein materials as the amino groups arising from lysine

react easily at room temperature with aldehyde groups.[25]

Glutaraldehyde was used as crosslinking agent to improve

water resistance and regulate degradation rate in soil of the

hybrid films (Table 4).[26]

WG cast films appeared red coloured, translucent,

flexible, with small amounts of insoluble residues dispersed

in the gelatin matrix. The mechanical properties of WG

corresponded to WG plasticised by water and glycerol

present in the scraps.WG cast films had elongation at break

(El) of 116%, ultimate tensile strength (UTS) of 11MPa and

Young’s modulus (YM) of 78 MPa (Table 5).

Addition of up to 20% ofWG to PVA (WGP90,WGP80)

increased the El from 211% for pure PVA up to 257% for

WGP80 and reduced both the UTS and YM, as reported in

Table 5. This behaviour can be attributed to the plasticizing

effect of glycerol present in WG. Blends with higher

concentration of WG exhibited mechanical properties that

were equivalent to that of pure WG.

Table 3. Composition of sprayed films based on waste gelatin(WG), polyvinyl alcohol (PVA), sugar cane bagasse (SCB) andglutaraldehyde as crosslinker (X).

Film Sample WasteGelatin

PVA Bagasse X

% % % %

WGSCB5 50 – 50 –WGSCB5X 50 – 49.75 0.25WGPSCB 40 10 50 –WGPSCBX 40 10 49.75 0.25

Table 4. Composition of blends based on waste gelatin (WG),poly(vinyl alcohol) and sugar cane bagasse (SCB). P¼ Poly(vinylalcohol) (PVA), X¼Glutaraldehyde.

Sample WG PVA SCB X

% % % %

WG 100 – – –WGP10 90 10 – –WGP20 80 20 – –WGP30 70 30 – –WGP50 50 50 – –WGP80 20 80 – –WGP90 10 90 – –PVA – 100 – –WGP80X 20 79.75 – 0.25WGX1 99.75 – – 0.25WGX2 99 – – 1.00WGX3 97.5 – – 2.50WGSCB20 80 – 20 –WGSCB20X 79.75 – 20 0.25

Table 5. Mechanical properties and relevant standard deviations(StDv) of waste gelatin (WG) based blends. El¼Elongation atBreak, UTS¼Ultimate Tensile Strength, YM¼Young Modulus,StDv¼ Standard Deviation.

Samplea) El StDv UTS StDv YM StDv

% MPa MPa

WG 116 22 11 1.2 78 12WGP50 133 13 8.3 0.9 79 17WGP70 132 14 14 0.5 86 14WGP80 257 28 22 2.3 133 13WGP90 235 24 26 0.8 200 45PVA 211 26 35 3.1 387 63WGP80X 241 23 22 1.9 128 15WGX1 146 16 10 1.6 33 1WGX2 140 29 10 2.5 33 7WGX3 300 17 13 2.0 10 3WGSCB20 14 2.1 10 0.9 228 27WGSCB20X 14 2.6 11 1.5 283 21

a) P¼ Poly(vinyl alcohol), X¼Glutaraldehyde, SCB¼ SugarCane Bagasse.



The addition of SCB fibres toWG hardened the resulting

films and darkened film colour. Accordingly, films of WG

containing 10–30% SCB were rather flexible, whereas

films containing 40–50% SCB were very hard and brittle.

An 80:20 WG/SCB blend (WGSCB20) appeared to be the

most interesting composition as far as filler content and

mechanical properties were concerned. WG and SCB were

quite compatible, and showed a good interfacial adhesion

(Figure 3).

This WG/SCB weight ratio appeared to be adequate to

completely cover and aggregate SCB fibres in the con-

tinuous matrix. Due to the casting process, SCB fibres

presented a random distribution and formed fibres aggre-

gates thus reducing El as showed by tensile tests. Indeed

WG cast film presented 116% El while in WGSCB20 El

was 14%. UTS were almost the same and YM increased

from 78 MPa for WG to 228 MPa for WGSCB20.

Hardening of gelatin with low molecular weight alde-

hydes is well documented in the literature.[27,28]

Crosslinking is predominantly due to Schiff’s base

formation by condensation of the aldehyde group and

the e-amino groups present in lysine and hydroxylysine

residues.

El in WG cast films increased significantly when the

glutaraldehyde was introduced in the formulations as re-

ported in Table 5. Thus depending upon crosslinking

density, temperature and diluent content a gelatin specimen

can behave as a rubber-like material capable of extending

by 700% or as a viscous liquid.[29] For a crosslinker content

of 0.25%, as inWGX1, Elwas 140% increasing to 300% for

2.5% of glutaraldehyde content as in WGX3. At the same

time YM decreased from 78 MPa in WG up to 10 MPa for

WGX3, whereas UTS did not significantly change. This

behavior of gelatin can be attributed to the disruption of the

helical structure of native gelatin allowing the chains to

assume a random coil conformation with glutaraldehyde

acting as a crosslinker among the chains.[30] On the other

hand, WGP80X and WGSCB20X did not show any signi-

ficant difference in comparison with WGP80 and

WGSCB20, thus indicating that 0.25% of glutaraldehyde

has a negligible effect on blend properties, also in accor-

dancewith results from previous studies of water sensitivity

and mineralization rates.[26,31]

3.1.2 Films Based on PVA and Natural Fillersfrom Agro-Industrial Waste

PVA Airvol 425 from Air Products & Chemicals Inc., had

Mn 100–146 KDa and 96% hydrolysis degree. Unmodified

commercial-grade corn/starch (USA) had approximately

30% amylose and 70% amylopectin content.

Cellulosic materials were from three different sources;

sugarcane bagasse (SCB) (USA), orange (OR) (Pakistan)

and apple (AP) (USA) peel were the remains of fruit residue

after juice extraction.[32] Composition andmoisture content

data of the selected agro-industrial waste are collected in

Table 6. All cellulosic materials were milled, sieved to

obtain particles sizes <0.188 mm (Figure 4).

Films were prepared by casting of water suspensions,

10% by weight, containing the desired amount of PVA,

fillers, plasticizers and starch.[32] While maintaining a 1/1

PVA/Fibre weight ratio, glycerol, urea, and starch were in-

troduced in the formulation as reported in Table 7.

Starch was added in some formulations to replace as

much of PVA as possible without compromising the film

properties. Addition of glycerol and urea softened the

Figure 3. SEM micrographs of WGB20 surface and fracture.

Table 6. Composition, on dry weight, of lignocellulosic fibres utilized in the formulation of composite mixtures.

Fibres Protein Fat Fiber Cellulose Lignin Hemicellulose Pectins Ash

% % % % % % %

SCB 4.8 1.9 33.7 36.6 10.6 – 12.4OR 12.9 6.6 14.7 17.7 4.8 32 11.3AP 4.7 11.5 27.3 21.6 21.1 12.5 1.3



films as glycerol acted as a plasticizer for PVA in PVA/

starch.[33,34] Urea also had a similar plasticizing effect on

PVA/SCB blends.[35] Effect of starch addition on mechan-

ical properties is reported in Figure 5.[36]

In PVA/SCB blends, elongation at break was mostly

unaffected by starch content while UTS increased with

starch addition, thus introduction of starch increased

cohesiveness of PVA/SCB films.

In PVA/OR blends starch addition caused significant

reduction in El with somewhat moderate variation in UTS.

Excellent film forming properties and flexibility was ob-

served in films even when starch concentration in formula-

tions exceeded 25%.

Whereas, in PVA/AP blends addition of starch increased

the presence of defects and small holes were detected in the

films, thus indicating a loss in mechanical properties due to

increased starch content.

3.2 Hybrid Composites by CompressionMolding Technique

Compression molded laminates based on PVA and natural

fibres were prepared by mixing the different components in

a kitchen aid mixer and the resulting formulations were

slowly introduced in a Brabender mixer, operating at an oil

bath temperature of 185 8C. The mixing was carried on at

low speed (30 rpm) for 15 min. The mixed samples were

kept in the mold for 15 min and then pressed at 14 ton for

20 min with a model 2518 Carver Lab Press at 180 8C,before cooling down at room temperature and retrieving

them from the mold. Compositions of the starting PVA/

organic filler mixtures used for the composites production

are reported in Table 8. About 20%water was added to each

composition before processing.

Since films based on PVA and OR showed to be homo-

geneous, flexible and more cohesive than composites based

on PVA and SCB or AP, OR was selected for the first

attempts to produce composites by compression molding.

A mixture of 60% PVA and 40% starch when processed by

compression molding, produced a hard and fragile com-

posite laminate. Introduction of glycerol, as in PStG, in-

creased flexibility but increased leaching of glycerol was

observed with time. When starch was substituted with OR

in this formulation, like in PORG, leaching of glycerol did

not occur. The substitution of starch with orange waste in

hybrid composite based on PVA and glycerol exhibited a

modest variation in mechanical properties. Thus, El, UTS

and YM values for both PStG and PORG films were quite

similar (Table 9).

The comparison of PORG with PStOR mechanical

properties suggested that the introduction of starch in the

formulation decreased moderately mechanical properties.

Composites prepared with AP (PStAP) presented similar El

values (61%), to composites prepared with OR (PStOR),

but higher UTS (9 MPa) and YM (57 MPa). PVA/SCB

resulted also harder with a reduced El (7%) than PVA/OR

and PVA/AP composites, but with a relatively high UTS

(8 MPa) and YM (171 MPa). The observed behaviour was

apparently due to the fibre composition and type. Both AP

and SCB have fibrous shape that confers hardness to the

Figure 4. SEM micrographs of sugar cane, orange, apple.

Table 7. Composition of films prepared by casting of hybrid water suspensions.

Samplea) PVA Natural fiber Glycerol Urea Starch

% % % % %

PSCBG, PAPG, PORG 33.3 33.3 16.6 16.6 –PStSCB1, PStAP1, PStOR1 31.0 31.0 15.0 15.0 8.0PStSCB2, PStAP2, PStOR2 28.6 28.6 14.3 14.3 14.3PStSCB3, PStAP3, PStOR3 25.0 25.0 12.5 12.5 25.0

a) PSCB series based on sugar cane bagasse (SCB) as filler, POR series based on orange (OR) as filler, PAP series based on apple (AP) asfiller, PVA Airvol 425.



composites resulting from the fibre orientation during

the processing in the Brabender; whereas in cast films the

random distribution of the fibres was rather a source of

fragility. Composites containing urea presented a higher El

as expected for the increased percentage of plasticizers

additives. PStORU presented a high El (148%), and a de-

creased UTS (1 MPa) and YM (2 MPa) in comparison with

PStOR.

3.3 Hybrid Composites by Injection Moldingand Baking Technique

Corn fibres (CF), co-products of the ethanol production

(USA), are an industrial name given to the pericarp fraction

of the corn kernel. Because of the inefficiency in themilling

during removal of the pericarp fraction, some of the kernel

endosperm is also removed. CF contain pericarp, and also

starch and protein from the endosperm. CF main use is

in animal feeds. The wet CF (60% moisture) costs about

$15/ton, while dried and ground at 10 mesh, costs about

$50/ton. The animal feed market cannot use all of the CF

currently on the market. CF had a composition of 1% fat,

14% protein, 25.5% starch, 59% lignocellulosic compo-

nent, and 0.5% ash.

CF were used to prepare composites with poly(vinyl

alcohol) (PVA) as a continuous matrix.[37]

A preliminary study was performed to identify suitable

plasticizers for PVA/CF composites preparation. Glycerol,

pentaerythritol and polyethylene glycol (PEG) were

chosen for preliminary investigation in variable composi-

tions with the same ratio of PVA and CF. By using

plasticizers, compounding could be done at 160–170 8Cto avoid any thermal degradation of fibre during the

processing. In the first composite (PCF1), glycerol was

added in the amount of 21% along with 11% pentaery-

thritol. This mixture produced a composite that was

cohesive and flexible. In the second mixture (PCF2), a

limited amount of 5%PEGwas introduced to further lower

viscosity of the melt. These compositions are presented in

Table 10.

The data reported in the Table 11 indicated that the

amount of plasticizer in the mixture impacted both the

processing parameters as well as the mechanical properties

of the composites.

Generally, composites with large amount of plasticizer

(PCF1 and PCF2) had much higher percent El. PCF2 com-

posite had much higher El, and lower UTS and YM com-

pared to PCF1 composite.

In all other composites, the plasticizer proportion was

similar to that of PCF2 except that corn starch was

introduced in the formulations, and the amount of CF

was progressively increased up to 32% (PCFSt3).Due to the

Figure 5. Effect of starch content on mechanical properties of films cast form water suspensions.

Table 8. Composition of the bio-based mixtures in compression molding.

Samplea) PVA Fibres Starch Glycerol Urea

% Type % % % %

PStG 44 – – 28 28 –PORG 44 OR 28 – 28 –PStSCB, PstOR, PStAP 34 SCB, OR, AP 22 22 22 –PStORU 25 OR 25 25 12.5 12.5

a) P¼ Poly(vinyl alcohol), St¼ Starch, G¼Glycerol, SCB¼ Sugar cane bagasse, OR¼Orange peel, AP¼Apple peel, U¼Urea.



increasedCF content, a decrease in the El was observed, but

YM generally increased. Interestingly, increased CF con-

tent did not significantly impact the UTS of samples. Also,

composites made with 32% fibres and only 29% PVA

resulted in cohesive extrudates.

Composites were also tested after storing at 23 8C and

50% RH for 1 year (Table 12).

Only small changes in tensile properties were observed

for composites stored for one year compared to the

composites stored for seven days under the same conditions

(Table 9). In composites containing no starch (PCF1 and

PCF2), changes in El were not significant. UTS and YM

decreased moderately for PCF1, and had almost the same

UTS, or moderately increased YM for PCF2. For samples

preparedwith 9 and 17% starch and approximately the same

fibres to PVA ratio as in composite PCF2, El was slightly

increased with storage, but UTS and YM were decreased.

These changes are probably an indication that materials

gain moisture during the storage. Composite PCFSt3

containing a higher ratio fibre to PVA had an increase in

UTS and YM and a decrease in El. This indicates that this

composite was getting stiffer and less flexible with age.

Interestingly, composites tested after one year of storage

had tensile properties similar to composites tested after

seven days of storage.

Food containers like lunch boxes are mainly produced by

expanded polystyrene (EPS) or coated paperboard and

largely contribute to the amount of plastics in municipal

solid waste streams. In oriental countries the littering based

on lunch boxes is referred as ‘‘white pollution’’. Efforts are

now beingmadeworld-wide to produce similar items based

on polymers from renewable resources such as starch.[38,39]

Potato starch, corn fibre, magnesium stearate and PVA

were first mixed by using a kitchen aid mixer with a wire

whisk attachment. For PVA free batter and with less then

50-weight part of fibres, gum arabic (1% by weight of

starch) was added to prevent starch settling. Water was

added to reach the required total solid content (Table 13).

The mixture was stirred at room temperature for 10 min in

the kitchen mixer operating at a medium speed.

Foam trays were prepared by using a lab model-baking

machine (model LB TRO) supplied by Franz Haas

Machinery of America, Richmond, (VA, USA). The

machine essentially consisted of two heated steel molds,

the top of which can be hydraulically lowered to mate with

the bottom half for a set amount of time. Dimensions of the

mold were 217 mm long, 134 mm wide, 19 mm deep, and

3 mm (plate separation). Baking temperature was set at

200 8C with a minimum residence time comprised between

120–180 s.

Sample trays were conditioned for oneweek at 23 8C and

50% RH, and mechanical tests were performed using an

Instron Model 4201 Universal Testing Machine equipped

with a cylindrical probe (80-mm diameter). The probe was

lowered onto the tray until a load of 0.5 N was reached and

then lowered at 30 mm �min�1. Parameters calculated were

the maximum force (MF) and deformation to MF (MFD).

Increase in the fibres content lowered both MFD andMF

values, indicating that irregular shape of fibre impacted the

foam strength (Figure 6).

Trays were still cohesivewhen composite contained high

fibre content (45%), but reinforced by PVA addition, as in

StPCF100. Thus PVApresence in tray composition improv-

ed bothMFDandMFvalues.Moreover, it was interesting to

learn that PVA (88% hydrolyzed) can directly be added as

a powder in a mixture thus saving both time and energy,

without having to pre-dissolve it in hot water as was

required in previous procedures.[40]

An amount of 100 ml of distilled water was poured in

trays made from compositions with and without fibre. Any

changes in trays weight and trays appearancewere recorded

after 30 min. Trays based on potato starch or strengthened

Table 9. Mechanical properties of composites based on PVA andlignocellulosic fibres. El¼Elongation at Break, UTS¼UltimateTensile Strength, YM¼Young’s Modulus, StDv¼ StandardDeviation.

Sample El StDv UTS StDv YM StDv

% MPa MPa

PStG 67 10 4.8 0.5 17.8 0.6PORG 68 5 3.7 0.4 16.3 1.1PStOR 56 2 3.4 0.1 15.3 1.1PStAP 61 10 9.3 0.4 57.2 6.1PStSCB 7 1 8.1 1.8 171.3 31PStORU 148 22 1.2 0.1 2.1 0.3

Table 10. Composition of bio-based mixtures consisting of PVA and CF processed by injection molding.

Samplea) PVA Corn Fiber Starch Glycerol PentaeErythritol PEG

% % % % % %

PCF1 42 26 – 21 11 –PCF2 40 25 – 20 10 5PCFSt1 36 23 9 18 9 5PCFSt2 33 21 17 17 8 4PCFSt3 29 32 14 14 7 4

a) P¼ Poly(vinyl alcohol), CF¼Corn fibres, St¼ Starch, PEG¼ Poly(ethylene glycole).



by PVA easily softened because of water addition, on the

contrary the tray containing a high percentage of fibres

(45%) and PVA (8%) as StPCF100 resulted softened but

still cohesive after water addition. This effect is attributed

to the fibres disposition in the external part of the trays,

thus foams have dense outer skin with large thin-walled

channels comprising the core as a result the faster drying of

the paste placed nearer to the mold (Figure 7).

Thus fibres introduction improves resistance at moisture

andwater effects due to the fibres disposition on the external

sides of the tray.

4. Degradation Testing of a TypicalBio-Based Polymeric Materialby Different Procedures

Degradation tests were performed by either manual or

automated methods on a bio-based selected material

consisting of a potato starch, corn fibres and PVA based

foamed tray (StPCF100) as reported in Table 13.

StPCF100 degradationwas recorded by amanualmethod

based on the back titration of alkaline solutions placed on

line to absorb the carbon dioxide produced from a re-

spirometric system according to a procedure developed in

our laboratory based on ASTM D 588-96.[41,42]

It is worth nothing however that determination of the

mineralization extent as performed by this last procedure,

based on the absorption of carbon dioxide under static

equilibrium conditions, is very much affected by the nature

of the carbon dioxide trapping solution and tipology of

back-titration. The best reliable combination of absorbing

solution nature and back-titration procedure appears the

one based on the use of KOH solution as carbon dioxide

trapping medium and back-titration of KOH excess after

addition of BaCl2 solution. This last ingredient allowed to

cancel out the influence of soluble K2CO3[43] on the visual

appreciation of the titration end point, as reported in

Figure 8 for a soil burial test performed on a sample of

cellulose, standard positive reference.

Alternatively StPCF100 degradationwas evaluated by an

automated method based on a closed circuit Micro-Oximax

respirometer system (Columbus Instruments, Columbus

OH). This system is a highly adaptable general purpose

closed circuit respirometer. It monitors the concentration of

gas containedwithin an enclosed head space (chamber) into

which the material being monitored is respiring. Periodic

sensing of the gas concentration, along with an equally

accurate measurement of the volume of the head space,

allows calculations of incremental and accumulated values

for consumption and production.

The profiles of the extent ofmineralizationvs time curves

recorded by the two methods were practically overlapping.

In both cases the samples underwent a rapid and extensive

mineralization (ca. 60% after 80 d).

Finally we can anticipate that the biodegradation extent,

as determined according to the described procedures, re-

sulted slightly lower than the value recorded for StPCF100

according to a gravimetric method based on the trapping

of the developed carbon dioxide on soda lime and talc.[44]

The determination was carried out by means of a Microbial

Oxidative Degradation Analyzer (MODA), kindly supplied

by Dr. Saida of the Saida Ironworks Co. Ltd (Japan). A

detailed analysis on the results of the performed trials as

compared to other methodologies will be reported in a

forthcoming paper.[45]

Table 13. Composition of the bio-based batter used to producetrays by foaming technique.

Battera) Starch PVA CornFiber

ArabicGum

MagnesiumStearate

% % % % %

St 96 – – 1 3StCF50 65 – 31 1 3StCF100 49 – 49 – 2StCF150 39 – 59 – 2StP 80 16 – 1 3StPCF50 58 11 29 – 2StPCF100 45 8 45 – 2StPCF150 36 7 55 – 2

a) St¼ Starch, CF¼Corn fibres, P¼ Poly(vinyl alcohol) (PVA).

Table 11. Mechanical properties of tensile bars from hybridcomposites stored at 23 8C, and 50%RHfor 7 d. El¼Elongation atBreak, UTS¼Ultimate Tensile Strength, YM¼Young’sModulus, StDv¼ Standard Deviation.

Sample El StDv UTS StDv YM StDv

% MPa MPa

PCF1 599 26 11.7 0.2 52.0 4.1PCF2 645 34 7.1 0.3 27.5 0.8PCFSt1 396 16 8.3 0.1 94.2 2.0PCFSt2 297 20 8.0 0.1 112.0 3.7PCFSt3 101 15 7.8 0.2 122.2 10.4

Table 12. Mechanical properties of tensile bars from hybridcomposites stored at 23 8C, and 50% RH for 365 days.El¼Elongation at Break, UTS¼Ultimate Tensile Strength,YM¼Young’s Modulus, StDv¼ Standard Deviation.

Mixture El StDv UTS StDv YM StDv

% MPa MPa

PCF1 613 15 9.5 0.2 34.2 2.5PCF2 619 16 7.2 0.1 38.6 1.9PCFSt1 415 48 6.2 0.2 65.0 1.2PCFSt2 356 24 6.4 0.3 84.7 9.4PCFSt3 95 7 8.6 0.2 183.3 8.7



5. CONCLUSIONS

This report outlines our ongoing research on the use of low

value, renewable feedstocks derived from the waste gene-

rated by the agriculture, food, pharmaceutical and tannery

industry for the utilization in composites and blends with

synthetic, semi-synthetic, and natural polymers.

A few case studies have been presented from which one

can envisage the potential of renewable materials from

unlikely sources otherwise destined to become waste. A

suitable and efficient infrastructure and knowledge base to

tap these resources could lead to recover cost, and provide

new opportunities for such polymeric materials benefiting

farmers, consumers, environment, and making industries

much more competitive. Additionally, new and novel tech-

nologies are bound to impact the packaging, agriculture as

well as horticulture. However, in order to fully succeed, the

utilization of polymeric feedstocks of both fossil as well as

of natural origin have to be rational, complimentary with

minimal environmental impact by processes and products

reflecting amuchmore balanced and harmonized vision of a

sustainable industrial development.

Whereas everybody is aware of the negative environ-

mental impact of fossil fuel feedstock consumption with an

overwhelming share as fuel-to-energy and hencewith GHG

(green house gas) emission, a minor awareness has been so

far built up on the limits of renewable resources.

Among the positive attributes stimulating a deeper atten-

tion on renewable resource one can quote:

. The availability of nearly unlimited raw material

resources.

. Prices of raw material feedstock estimable on medium-

long term.

. High added-value bio-based formulations and items by

the utilization of agricultural over productions, and agro-

industrial and agro-food wastes.

. Easy and convenient disposal of post-consume items in

composting infrastructures with potential economic

return from quality compost production.

. Propensity to environmental degradation of bio-based

plastic articles.

. Neutrality of bio-based polymeric materials and plastics

in respect of CO2 balance.

. Unsatisfactory properties of bio-based polymeric mate-

rials and plastics in comparison to the petrol-based

counterparts.

The drawbacks that have to be mentioned imply:

. Unsatisfactory waste disposal policy and lack of suitable

infrastructure. Progresses are however ongoing nowa-

days in world-wide effort aimed at a more sound waste

management.

Figure 7. Scanning electronmicrographs of :a) foams based on potato starch (St), b) foams based on potato starch/corn fibres (StCF100),c) foams based on potato starch/PVA (StP), d) foams based on potato starch/PVA/corn fibres (StPCF100).

Figure 6. Dependence of maximum force (MF) and deformation at maximum force (MFD) on CF content.



. Lack of world-wide accepted regulatory definitions and

tests. Indeed the considerations exposed for the above

point hold true also for this point. A lot of progresses have

been made in the last few years.

. Lack of incentives for the formulation and use of eco-

compatible bio-based polymeric materials and plastics.

. Lack of incentives for the formulation and use of eco-

compatible bio-based polymeric materials and plastics.

. Relatively high prices tied-up with high cost for research

and development and yet limited scale productions and

consumption.

These last considerations further substantiate the future

trend of industrial and social development for a more rati-

onal and integrated utilization of fossil and renewable

resources both as energy outlets and food and non-food

applications.

A common operative table among decision makers,

industrialists, scientists, customers and end-users would

certainly help to speed up the integrated process neces-

sary to shade light on a knowledge-based sustainable

development.

Acknowledgement: The authors wish to thank Mrs VassilkaIlieva Ivanova for her help in updating the literature relevantto the topic and effort in running some degradation experiments.The financial support by MIUR-Cofin 2002 is gratefullyacknowledged.

[1] H. Roper, NutraCos 2002, 37.[2] N. El Bassam, Renewable Energy 2001, 24, 401.[3] R. M. Rowell, A. R. Sanadi, D. F. Caulfield, R. E. Jacobson,

‘‘Utilization of Natural Fibres in Plastic Composites:

Problems and Opportunites’’, in: Lignocelluloisc-PlasticComposites, A. L. Leao, F. X. Carvalho, E. Frollini,Eds., UNESP, Sao Paulo 1997, pp. 23–52.

[4] S. Warwel, F. Bruse, C. Demes, M. Kunz, M. R. Klaas,Chemosphere 2001, 43, 39.

[5] E. A. MacGregor, C. T. Greenwood, ‘‘Polymers in Nature’’,John Wiley & Sons, New York 1980, p. 391.

[6] R. A. Young, ‘‘Utilization of Natural Fibres: Characteriza-tion, Modification, and Applications’’, in: Lignocellulosic-Plastic Composites, A. L. Leao, F. X. Carvalho, E. Frollini,Eds., UNESP, Sao Paulo 1997, pp. 1–22.

[7] S. M. Lahalih, S. A. Akashah, F. H. Al-Hajjar, Ind. Eng.Chem. Res. 1987, 26, 2366.

[8] R. Coffin,M. L. Fishman, T. V. Ly, J. Appl. Polym. Sci. 1996,57, 71.

[9] E. Chiellini, P. Cinelli, E. Grillo Fernandes, E. R. Kenawy,A. Lazzeri, Biomacromolecules 2001, 2, 806.

[10] E. Chiellini, P. Cinelli, S. H. Imam, L. Mao, ‘‘CompositeFilms Based on Poly(vinyl alcohol) and LignocellulosicFibers’’, in: Biorelated Polymers – Sustainable PolymerScience and Technology, E. Chiellini, H. Gil, J. Buchert,G. Braunegg, M. Van der Zee, P Gatenholm, Eds., KluwerPlenum Press, New York 2001, pp. 87–98.

[11] P. Cinelli, E. Chiellini, S. H. Gordon, S. H. Imam,Macromol.Symp. 2003, 197, 143.

[12] B. L. Kay, R. A. Evans, J. A. Young, Agronomy J. 1977, 69,555.

[13] J. A. Young, B. L. Kay, R. A. Evans, Agronomy J. 1977, 69,115.

[14] M. G. Mellon, The Landscape Architet and Specifier News1989, 5, 40.

[15] M. G. Mellon, Southern Golf-Landscape and ResortManagement 1990, May-June.

[16] R. C. Stefanson, Aust. J. Soil Res. 1974, 12, 59.[17] P. Cinelli, ‘‘Formulation and Characterization of Environ-

mentally Compatible Polymeric Materials for AgricultureApplications’’, PhD Thesis, Pisa University, 1999.

[18] E. Chiellini, P. Cinelli, S. D’Antone, V. I. Ilieva, S. Magni,S. Miele, S. Pampana, Macromol. Symp. 2003, 197, 133.

[19] US 09/450,016 (1999), Agroqualita S.R.L., invs: E.Bargiacchi, E. Chiellini, P. Cinelli, A. Corti, S. Magni,S. Miele.

[20] PCT/EP00/11676, (2000) Agroqualita S.R.L., invs: E.Bargiacchi, E. Chiellini, P. Cinelli, A. Corti, S. Magni,S. Miele.

[21] G. W. Mc Kee, Pennsylvania Agricultural ExperimentStation, 1963, 2778.

[22] L. A. de Graaf, P. Kolster, Macromol. Symp. 1998, 127,51.

[23] L. H. Sperling, C. E. Carraher, ‘‘Gelatin’’, in: Encyclopediaof polymer Science and Engineering, H. F. Mark,N. M. Bikales, C. G. Overberger, G. Menges, Eds., J. Wiley& Sons, New York 1988, Vol. 12, p. 672.

[24] E. Chiellini, P. Cinelli, A. Corti, E. R. Kenawy, A. Lazzeri,Proceedings from the 3rd International Symposium onNatural Polymers and Composites, and the Workshop onProgress in Production and Processing of Cellulosic Fibresand Natural Polymers, Sao Pedro, Brazil, May 14–17, 2000,pp. 281–292.

[25] H. Akin, N. Hasirci, J. Appl. Polym. Sci. 1995, 58, 95.[26] E. R. Kenawy, P. Cinelli, A. Corti, S. Miertus, E. Chiellini,

Macromol. Symp. 1999, 144, 351.[27] P. R. Chatterji, J. Appl. Polym. Sci. 1989, 37, 2203.[28] G.A.Digenis, T. B. Gold, V. P. Shah, J. Pharm. Sci. 1994, 83,

915.

Figure 8. Comparison of mineralization rate as determined bytitration of respectively: Ba(OH)2, KOH in the presence of solublecarbonate, and KOH after precipitation of the carbonate withBaCl2.



[29] I. V. Yannas, J. Macromol. Sci. Macromol. Chem. 1972, 7,49.

[30] L. H. H. Olde Damink, P. J. Dijkstra, M. J. A. Van Luyn, P. B.Van Wachem, P. Nieuwenhuis, J. Feijen, J. Mater. Sci.:Mater. Med. 1995, 6, 460.

[31] E. Chiellini, P. Cinelli, A. Corti, E. R. Kenawy, E. F. Grillo,R. Solaro, Macromol. Symp. 2000, 152, 83.

[32] E. Chiellini, P. Cinelli, S. H. Imam, L. Mao, Biomacromo-lecules 2001, 2, 1029.

[33] W. Lawton, G. F. Fanta, Carbohydr. Polym. 1994, 23, 275.[34] L. Mao, S. H. Imam, S. H. Gordon, P. Cinelli, E. Chiellini,

J. Polym. Environ. 2002, 8, 205.[35] E. Chiellini, P. Cinelli, R. Solaro, M. Laus, J. Appl. Polym.

Sci. 2003, in press.[36] E. Chiellini, P. Cinelli, E. Grillo Fernandes, E. R. Kenawy,

A. Lazzeri, ‘‘Biorelated Polymers, Sustainable PolymerScience and Technology’’, E. Chiellini, H. Gil, G. Braunegg,J. Buchert, P. Gatenholm, M. Van der Zee, Eds., KluwerAcademic-Plenum Publishers, New York 2001, p. 101.

[37] P. Cinelli, J. W. Lawton, S. H. Gordon, S. H. Imam,E. Chiellini, Macromol. Symp. 2003, 197, 115.

[38] J. W. Lawton, R. L. Shogren, K. F. Tiefenbacher, CerealChem. 1999, 76, 682.

[39] R. L. Shogren, J. W. Lawton, K. F. Tiefenbacher, Ind. CropsProd. 2002, 16, 69.

[40] R. L. Shogren, J. W. Lawton, K. F. Tiefenbacher, L. Chen,J. Appl. Polym. Sci. 1998, 68, 2129.

[41] E. Chiellini, A. Corti, Macromol. Symp. 2003, 197, 381.[42] ASTM D 5988-96 Standard test method for Determining

Aerobic Biodegradation in Soil of Plastic Materials orResidual Plastic Materials After Composting, Annual Bookof ASTM Standards, 1997, Vol. 08.03.

[43] A. Modelli, B. Calcagno, M. Scandola, J. Environ. Polym.Degrad. 1999, 7, 109.

[44] EP0908513 (1999), SAIDA Iron Works co Limited, inv.:U. Shogo.

[45] E. Chiellini, A. Corti, P. Cinelli, M. Martera, J. Environ.Polym. Degrad., submitted.



Environmentally Degradable Bio-Based Polymeric Blends and Composites

Documents

Transcript of Environmentally Degradable Bio-Based Polymeric Blends and Composites