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Poly-Paper: A Sustainable Material for Packaging, Based on Recycled Paper and Recyclable with Paper

  • Ghelfi Ondulati

Abstract and Figures

Background: Until now, environmental sustainability issues are almost entirely unsolved for packaging materials. With the final aim of finding materials with a single recycling channel, cellulose fiber/poly(vinyl)alcohol composites were investigated. Methods: After extrusion and injection molding, samples of composite with different cellulose fiber content (30%, 50% and 70% w/w) were tested. Results: Tensile mechanical tests exhibited an improvement in composite stiffness when the reinforcement content was increased together with a decrease in composite elongation. Solubility tests performed at room temperature and 45°C showed different behavior depending on the water-resistant film applied on the composite (50% cellulose fiber content). In particular, the uncoated composite showed complete solubility after 2 hours, whereas at the same time point, no solubility occurred when a non-water-soluble varnish was used. Conclusions: The proposed composites, named Poly-paper, appear to warrant further investigation as highly sustainable packaging.
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J Appl Biomater Funct Mater 2016; 14(4): e490-e495
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sustainable packaging should have a single separate collec-
on and recycling channel.
There is no doubt that taking eecve steps in view of pack-
aging sustainability will imply using a single material, or rather
materials with dierent properes and funconal performance
but with the same recycling channel. The above consideraons
led to our interest in developing a composite material charac-
terized by high environmental sustainability (1).
Paper and board can best sasfy these needs: recycling of
corrugated board, newspapers and magazines has been cus-
tomary for some me now, even before the term recyclable
became so popular. Sustainability is ensured by the fact that
recycling simply requires placing the discarded parts in the
paper-and-board bins available close to our homes. However,
recycling of our new material alongside the waste paper col-
lected for recycling required using a water-soluble matrix. We
chose polyvinyl alcohol (PVA), a polymer-based material pro-
duced without diverng ferle lands from agriculture, cap able
of melng in water and forming nontoxic composites (2, 3).
We called this material poly-paper. Poor resistance to water
due to the water-soluble matrix is obviously not an issue in
this case, because the resistance of Poly-paper to water (which
varies according to temperature) is anyway greater than that
of corrugated board.
DOI: 10.5301/jabfm.5000335
Poly-paper: a sustainable material for packaging, based
on recycled paper and recyclable with paper
Barbara Del Curto1,2, Nadia Barelli1, Mauro Profaizer3, Silvia Farè1,2, Maria Crisna Tanzi2, Alberto Cigada1,2,
Giulia Ognibene4, Giuseppe Recca5, Gianluca Cicala2,4
1 Department of Chemistry, Materials and Chemical Engineering “Giulio Naa”, Politecnico di Milano, Milan - Italy
2 UdR Consorzio INSTM, Florence - Italy
3 Ghel Ondula spa, Buglio in Monte, Sondrio - Italy
4 Department DICAR, University of Catania, Catania - Italy
5 CNR-IPCB, Catania - Italy
Popular packaging materials today involve unsolved en-
vironmental sustainability issues. The main reason is that
packaging is, in most cases, made of mulple materials (cor-
rugated board, polystyrene foam, polyethylene etc.), which
are oen disposed of unsorted. Consider the packaging of a
TV set or any other home appliance: It includes corrugated
board for the outer case, polystyrene foam for inner lling,
bubble polyethylene wrap and sundry plasc parts. Each of
these materials has a dierent recycling channel (oen a
complicated one, as in the case of polystyrene foam). Truly
Background: Unl now, environmental sustainability issues are almost enrely unsolved for packaging materials.
With the nal aim of nding materials with a single recycling channel, cellulose ber/poly(vinyl)alcohol compos-
ites were invesgated.
Methods: Aer extrusion and injecon molding, samples of composite with dierent cellulose ber content
(30%, 50% and 70% w/w) were tested.
Results: Tensile mechanical tests exhibited an improvement in composite sness when the reinforcement con-
tent was increased together with a decrease in composite elongaon. Solubility tests performed at room temper-
ature and 45°C showed dierent behavior depending on the water-resistant lm applied on the composite (50%
cellulose ber content). In parcular, the uncoated composite showed complete solubility aer 2 hours, whereas
at the same me point, no solubility occurred when a non-water-soluble varnish was used.
Conclusions: The proposed composites, named Poly-paper, appear to warrant further invesgaon as highly
sustainable packaging.
Keywords: Cellulose ber, Composite, Polyvinyl alcohol, Solubility, Tensile strength
Accepted: October 18, 2016
Published online: November 1, 2016
Corresponding author:
Prof. Barbara Del Curto
Diparmento di Chimica
Materiali e Ingegneria Chimica “Giulio Naa”
Politecnico di Milano
Via Mancinelli 7
20131 Milano, Italy
Del Curto et al e491
© 2016 The Authors. Published by Wichg Publishing
A study by Zhang et al (4) focused on the inuence of the
chemomechanical treatments of cellulose on the physico-
chemical properes of a cellulose/PVA composite material
with 23% cellulose. The improvement of tensile strength and
elongaon has been shown to be a funcon of the decrease
of the size of cellulose bers, and was correlated with the
combined expansion of the specic surface area of the laer,
due to the increase of the grinding cycles that cellulose bers
undergo before mixing and extrusion with PVA.
In a study by Kaushik et al (5), cellulose bers were added
to a thermoplasc starch matrix (TPS), and mechanical prop-
eres were shown to improve as a funcon of the increase
of the cellulose nanobers, at a maximum demonstrated
15% rate. Huda et al (6, 7) showed that recycled news-
paper bers can be used as reinforcements in poly(lacc
acid) (PLA) and polypropylene (PP) in place of talc. In a dif-
ferent paper, Huda et al (8) postulated the use of recycled
newspaper bers as a replacement for glass bers. The
economic and environmental advantages of using newspa-
per-derived ber were outlined. In a recent study, Serrano
et al (9) demonstrated the technical feasibility of the use
of newspaper bers over glass bers for the producon of
products such as doors, windows, furniture and automove
interior parts.
The aim of the present study was to invesgate novel for-
mulaons using signicantly higher rates of cellulose to ensure
easy recycling in water of the biocomposite. Furthermore, an-
other purpose of the work was to assess the feasibility of the
developed formulaon to be used as a novel soluble material,
Poly-paper, for processing using the fused deposion modeling
Materials and methods
The polymer selected as matrix was an experimental
formulaon based on water-soluble PVA with degree of
hydrolysis between 75% and 90%, average molecular weight
(Mw) between 75 and 150 kDa and a polydispersity index
(Mw/Mn) between 2.5 and 4.3. The cellulose bers selected
as reinforcement had dimensions lower than 45 μm (>45 μm
0%-0.1%), and bulk density in the range of 232-248 g/L. All
materials were vacuum dried at 50°C for 48 hours prior to
Specimen preparaon
Composites were melt blended in a corotang twin-
screw extruder (Lab-Compounder KETSE 20/40D EC; Braben-
der, Duisburg, Germany). The extruder line was equipped
with a side feeder (MT1-12; Brabender) to feed powder
directly into the melt and a volumetric feeder (DRS28) to
feed the pellet into the extruder barrel. The sequence of
compounding was as follows: modied PVA pellets were
fed through the input hopper with the volumetric feeder;
nally the cellulose was dosed from the extruder opening
side with the side feeder. The temperature paern of the
extruder was 190°C-190°C-195°C-195°C-190°C-190°C-180°C
from input to output zones. The composites were pellezed
from the extruded lament, to be processed by injecon
molding. Composites pellets were dried (24 hours at 50°C
under vacuum) before injecon molding. From all compos-
ites, pellet dog bone specimens with dimensions according
to ASTM D638 were fabricated using a 12 mL microinjecon
molder (DSM Xplorer) at 190°C melt temperature and 60°C
mold temperature with injecon and holding pressure of
16 bar. The specimens were allowed to cool in the mold for
5 minutes before extracon. This allowed us to obtain homo-
geneous and strong postextrusion materials with cellulose
ber rates ranging from 30% to 50% (Fig. 1B, C). As shown,
without bers, the post-extrusion modied PVA only matrix
had a thin texture (Fig. 1A), and became unsubstanal with
70% cellulose bers (Fig. 1D).
The possibility to obtain laments by extrusion was nally
explored by checking, with posive results (data not shown),
whether the material could be used to produce pellets (Fig. 2)
in view of injecon molding.
Fig. 1 - Extrusion tests on: (A) modied polyvinyl alcohol (PVA) alone, (B) modied PVA + 30% cellulose bers, (C) modied PVA + 50%
cellulose bers, (D) modied PVA + 70% cellulose bers.
Poly-paper, a sustainable packaging material
© 2016 The Authors. Published by Wichg Publishing
Experimental characterizaon techniques
Thermal stability of cellulose bers was studied using a
TGA-500 V6.7 instrument (TA Instrument), coupled with TA
Instrument Explorer operang soware. The analyses were
performed under dynamic heang condions, from 50°C to
800°C under nitrogen ow (60 ml/min), at a heang rate of
10°C/min, using about 2 mg of sample. Data recorded show
the thermal behavior of cellulose bers in terms of weight
loss percentage increasing the test temperature.
The morphology of the dried cellulose bers was observed
by EVO Scanning Electron Microscope (Zeiss, Cambridge, UK)
at room temperature. The bers were stuck on the sample
stub. The samples were gold spuered up to a thickness of
20 nm by means of a Emitech K-550 spuer coater (Emitech,
Ashford, Kent, UK). An accelerang voltage of 15 kV was
used to collect the micrographs. The surface of the tensile-
fractured specimens was also analysed aer gold spuering.
The same observaon condions used for the dry bers were
used to analyze composite samples.
Tensile properes of the injecon molded specimens were
measured by using an Instron 5985 universal tesng machine,
equipped with a load cell of 10 kN in accordance to ASTM D638
standard. The tensile specimens had a length, width and thick-
ness of narrow secon of 165, 13 and 3.2 mm, respecvely.
These dimensions are in accordance with specimen Type I as
reported in the ASTM D638 standard. Five specimens were
tested for each composite, with a constant speed of 5 mm/min,
while compliance correcon was used. System control and
data analysis were performed using Instron’s Blue Hill soware.
The ability of the composite material (with 50% cellulose
ber) to melt by soaking with water was then evaluated by
simulang maceraon condions. Briey, tests were per-
formed on specimens (40 × 40 × 5 mm), both at room temper-
ature and at 45°C. Some specimens were supercially coated
with a varnish lm to check for possible water resistance of
the material in view of specic applicaons.
Results and discussion
Characterizaon of cellulose bers
Thermal stability of the cellulose bers was invesgated
by thermogravimetric analysis (TGA) under nitrogen ow. In
Figure 3, the TGA result for dried cellulose ber is reported.
The TGA curve showed 3 thermal degradaon steps ranging
from 200°C to 800°C. In parcular, the rst degradaon step
at 267°C was due to the degradaon of cellulosic substances,
such as hemicellulose and cellulose. The second degradaon
(T = 383°C) of the decomposion was related to the degrada-
on of noncellulosic materials in the bers, while, the nal
degradaon steps between 620°C and 800°C were due to mi-
nor components in the bers. The residual char accounted for
19% of the inial weight. The thermal stability of the cellulose
bers up to 267°C ensured the processability of the compos-
ites up to 195°C which was the maximum selected tempera-
ture in the extruder for compounding.
The morphology of the cellulose ber obtained by the pa-
per recycling process was invesgated with SEM (Fig. 4). The
recycled paper appeared in a brillary form, with bers rang-
ing from 50 to 200 µm. The surface of the brils appeared
rough probably due to the recycling method used.
Tensile properes of the composites
The tensile properes of the modied PVA/cellulose compos-
ites were compared with neat modied PVA. The stress–strain
Fig. 2 - Poly-paper pellets obtained by extrusion.
Fig. 3 - Thermogravimetric analysis curve for the cellulose bers.
Del Curto et al e493
© 2016 The Authors. Published by Wichg Publishing
Fig. 4 - SEM images of the dried cellulose ber from recycled paper: (A) ×300 magnicaon (scale bar: 100 μm); (B) ×1,000 magnicaon
(scale bar: 20 μm).
curves of the neat modied PVA and of the composites are re-
ported in Figure 5. The stress–strain curves showed a necking
extension for the neat modied PVA sample. The yield stress for
the composites decreased slightly with increasing the cellulose
ber content. The tensile modulus showed sharp increases with
tensile modulus varying from 3.57 to 5.19 and 7.17 GPa, with an
increase of 45% and 101% for the composites with 30 wt% and
50 wt% of cellulose, respecvely (Tab. I). This indicates that the
stress would be expected to be transferred from the polymer
matrix to the stronger cellulose ber, indicang also a good in-
terfacial adhesion. Similar results were obtained by Huda et al (6)
with the addion of 30 wt% recycled newspaper bers to PLA. In
addion, the mechanical properes here obtained were in the
range of, or even higher than, those reported by Graupner for
PLA-reinforced composites for use in the automove sector (10).
In addion, the use of natural or recyclable constuents makes
the composites studied interesng as environmentally friendly
materials (11).
The tensile-fractured surface of the specimens consid-
ered was analysed by SEM (Fig. 6). Neat PVA (Fig. 6A) showed
a rough surface, conrming the mechanical data for a duc-
le behavior, while the surface appeared less rough for the
sample modied with 30 wt% cellulose bers (Fig. 6B). The -
bers were covered by matrix in both of the samples at 30 wt%
(Fig. 6B) and 50 wt% (Fig. 6C, D). However, in the sample with
50 wt% of bers, the higher ber volume fracon resulted in
a more complex surface topology.
Stability test
The stability tests showed that the composite mate-
rial (Fig. 7) was completely dissolved within about 2 hours
when uncoated (cellulose 50 wt% in Fig. 7) and coated with
2 dierent percentages (3.3% and 10%) of ketone-aldehyde
resin. When the composite was coated with a varnish, either
non-water-soluble or water-soluble, the coated composite
specimens showed good stability up to the end of the test.
The obtained results showed that if appropriately coated,
Fig. 5 - Representave tensile stress–strain curves of the composites:
neat polyvinyl alcohol (PVA) (A), and PVA/30 wt% cellulose bers (B).
the composite can be stable for a longer me, hence it can
be used also in an environment with a high percentage of
Poly-paper, a sustainable packaging material
© 2016 The Authors. Published by Wichg Publishing
TABLE I - Mechanical parameters obtained in the tensile characterizaon test performed on the composites reinforced with dierent per-
centages of cellulose (30 and 50 wt%) compared with neat PVA (0 wt%)
Fibers Yield stress (MPa) Tensile modulus (GPa) Strain to failure (%)
0 wt% 65.01 ± 0.57 3.57 ± 0.13 15.45 ± 11.28
30 wt% 58.10 ± 1.08 5.19 ± 0.09 1.49 ± 0.07
50 wt% 51.13 ± 9.46 7.17 ± 0.14 0. 84 ± 0.19
PVA = polyvinyl alcohol.
Fig. 6 - SEM images of the cross-
sec on area of represent ave spec i-
mens aer tensile tests: (A) neat
polyvinyl alcohol (PVA; ×800 magni-
caon); (B) 30 wt% cellulose/PVA
composite (×700 magnicaon); (C)
50 wt% cellulose/PVA composite
(×800 magnicaon); (D) 50 wt%
cellulose/PVA composite (×1.3k
magnicaon). Scale bar: 20 μm.
Fig. 7 - Solubility kinec s of the 50% cellulos e b er/ PVA comp os ite (C 50) un co ated and coated with die re nt per centages of ketone- ald eh yd e
resin (3.3% and 10% resin), with non-water-soluble varnish and with water-soluble varnish: (A) at room temperature and (B) at 45°C.
Once completed, the newly developed material (which
is called Poly-paper) is expected to represent a signicant
step toward the development of highly sustainable packag-
ing, being a very s and strong material that can be shaped
into complex forms and integrated with corrugated board for
Del Curto et al e495
© 2016 The Authors. Published by Wichg Publishing
inclusion in the recycling process of the board itself. Our nd-
ings resulted in the ling of a patent co-owned by the Milan
Polytechnic and NextMaterials srl (12, 13).
Financial support: Bando Congiunto INSTM – Regione Lombardia
2016 - Project IN-RL4 GreenPack.
Conict of interest: None of the authors has any nancial interest
related to this study to disclose.
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... The cellulose had a bulk density in the range of 232-248 g/L, and a fibrillar form with a length lower than 45 microns. The cellulose came from the recycling of cardboards, as did the cellulose used in the previous studies [13]. ...
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... These materials come from different origins, have different functions, but also a different recycling channel. In industrial case studies, different materials are usually combined in a single packaging: corrugated cardboard, printed paper, polystyrene foam, polyethylene and various other plastic components [1]. ...
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... Separating and recycling the individual layers is, however, very challenging and only possible with extensive chemical treatments [30,31]. A water-soluble release layer between the barrier coating and paperboard can be helpful to easily separate the coating from the paperboard so that it does not hinder recyclability of the paperboard; for example, a polyvinyl alcohol coating on paperboard [32]. ...
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... Paper substrates are commonly considered for food packaging applications as they cause less damage to the environment, and are often recyclable depending on the coatings or additives introduced (Del Curto et al. 2016). Cellulose, the key material of paper, is frequently used as a modifier or reinforcement to polymers commonly used in plastic films or other similar applications (Lavoratti et al. 2016), but is itself one of the most widely available and studied biopolymers (Roig et al. 2011;Sofla et al. 2016;Ioelovich 2016). ...
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Supercritical impregnation may be used to impart specific functional properties into porous substrates such as wood, textiles, or paper. In the current study, food-grade beeswax (BW), carnauba wax (CW) and vegetable wax (VW) were impregnated into paper substrates to improve their hydrophobicity and mechanical strength. The contact angle of impregnated and annealed samples was approximately 110–120° when annealed at 140 °C, and 130° when annealed at 160 °C. SEM analyses revealed that dual micro- and nano-scale roughness was generated in impregnated paper substrates that also underwent annealing. FTIR analysis showed evidence of H-bonding between the waxes and cellulose, but this was more dominant with BW/CW compared with VW due to the different chemical structures of the waxes. Annealed samples showed lower intensity FTIR peaks, tentatively confirming a phase transition of the waxes as a result of the annealing. A reduced tan delta signal up to the secondary alpha transition temperature for paper was observed with BW/CW impregnated samples, indicating the formation of additional chemical bonds between cellulose and wax. Compared with untreated paper substrates, the sharp decrease in storage modulus during degradation occurred at temperatures up to 10 °C higher for wax-impregnated papers, and up to 40 °C lower for baseline papers impregnated and annealed without wax. It is believed that the H-bonds between the waxes and cellulose were able to withstand higher temperatures in the degradation region, thus offsetting the effects of sample preparation.
... The classes of packaging materials are numerous, since there are many functions that packaging materials must fulfil. In many industrial case studies, different classes of materials are usually combined in a single package: corrugated cardboard, printed-paper, polystyrene foam, low-density polyethylene and various other plastic components, etc.. (Del Curto et al., 2016). Each of these materials follows a different path for collection, disposal and recycling. ...
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Polymeric materials used for packaging have unsolved environmental sustainability problems. The ideal packaging must be recyclable and/or compostable, with a unique recycling channel. This is focused on the development of an innovative eco-composite material based on water-soluble polymeric matrix reinforced with cellulose fibers up to 60 % w/w: Poly-Paper. The material can be processed by conventional processes of thermoplastics (extrusion, thermoforming, injection moulding, 3D printing) and can be recycled together with paper-based materials. This work describes the innovative expanded version of Poly-Paper and the developed forming technology: Water Shaping, able to give the material a great impact and energy absorption capacity in packaging applications.
... Rahman et al (26) investigated the effect of raster angle on the mechanical properties of PEEK printed specimens. Cicala et al (27) extended the study of PEEK printed specimens using optimized formulations, comparing the results obtained to those of commercial and development materials and composites filled with carbonaceous and natural fillers (28). To date, in the scientific literature, only these papers have reported the investigation of PEEK as a possible material for FDM, despite the fact that PEEK is widely recognized as the polymer of choice for selective laser sintering in demanding applications. ...
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Background: Among additive manufacturing techniques, the filament-based technique involves what is referred to as fused deposition modeling (FDM). FDM materials are currently limited to a selected number of polymers. The present study focused on investigating the potential of using high-end engineering polymers in FDM. In addition, a critical review of the materials available on the market compared with those studied here was completed. Methods: Different engineering thermoplastics, ranging from industrial grade polycarbonates to novel polyetheretherketones (PEEKs), were processed by FDM. Prior to this, for innovative filaments based on PEEK, extrusion processing was carried out. Mechanical properties (i.e., tensile and flexural) were investigated for each extruded material. An industrial-type FDM machine (Stratasys Fortus® 400 mc) was used to fully characterize the effect of printing parameters on the mechanical properties of polycarbonate. The obtained properties were compared with samples obtained by injection molding. Finally, FDM samples made of PEEK were also characterized and compared with those obtained by injection molding. Results: The effect of raster to raster air gap and raster angle on tensile and flexural properties of printed PC was evidenced; the potential of PEEK filaments, as novel FDM material, was highlighted in comparison to state of the art materials. Conclusions: Comparison with injection molded parts allowed to better understand FDM potential for functional applications. The study discussed pros and cons of the different materials. Finally, the development of novel PEEK filaments achieved important results offering a novel solution to the market when high mechanical and thermal properties are required.
Alkyl ketene dimer (AKD) and vegetable wax (VW) are suitable contenders for supercritical impregnation (SCI) processes, where the waxes may be deposited onto paper fiber surfaces to improve their hydrophobicity for food packaging applications. The solubility of both waxes in supercritical carbon dioxide (scCO2) with n-heptane cosolvent was measured (40 – 60 oC and 10 – 18 MPa). VW was two orders of magnitude more soluble in scCO2 compared with AKD, and both sets of data were validated using the Chrastil empirical equation. SCI of AKD wax into paper matrixes was performed at pre-determined solubility conditions, and the resulting hydrophobicity was measured. Results demonstrated that annealing the samples (4 h, 140, 160, 180 oC) immediately following impregnation generally enabled a more rapid development of the CA over a 2-week period. Crucially, using impregnation temperatures and pressures that maximized AKD solubility in scCO2 resulted in CA up to 130o. Gravimetric analysis of the impregnated samples confirmed the expected deposited wax quantities to within 25% of the solubility quantities. Scanning electron microscopy (SEM) imaging revealed better distribution of AKD in annealed samples and partially confirmed that more intricate structures were responsible for higher measured CA. These results explicitly connect the intuitive relationship that higher solute solubility in scCO2 should lead to bulk property improvements (i.e. higher CA or hydrophobicity) after SCI. Continued research in this area will enable the development of metrics, linking solubility conditions to desired bulk material properties, and is expected to lead to innovative packaging of green materials and processes.
Currently used materials for packaging present unresolved issues connected to environmental sustainability. A truly sustainable packaging must have a clear collection and recycling channel, and, at the same time, it should not pollute the environemt in case of wrong disposal. This chapter presents an innovative ecocomposite material appropriate for packaging applications. The new composite is called “Poly‐paper” because it brings together two familes of materials that play a key role in today's packaging: Polymers and paper. Poly‐paper is based on a biodegradable eco‐compatible polymer reinforced with cellulose fibers. It is a biodegradable and recyclable material that can be processed as a conventional thermoplastic polymer but can be also recycled into the paper and cardboard recycle chain. In the packaging industry, poly‐paper can replace various plastic components in a responsible way and it can be easily integrated and recycled with paper and cardboard packaging.
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In this study we present results on the environmental impacts associated to the production of an interior side door panel made of hemp fiber and epoxy resin, by using the life cycle assessment method. The composite was manufactured through vacuum bag infusion that improves the fiber-to-resin ratio and results in a lighter product. In this case, the weight of the panel is a very important aspect for the impact evaluation because the vehicle use phase is dominant compared to the manufacture and end of life phase. Recycling of the composite through coprocessing in cement kilns was assumed as waste scenario. One limit of thermoset composite wastes is that they are usually landfilled because recycling is not easy. Recent applications of recycled composite have shown that thermoset composite regrind is an ideal raw material for cement manufacturing. The mineral composition of the regrind is consistent with the optimum ratio between calcium oxide, silica, and aluminium oxide. Additionally, the organic fraction supplies fuel for the reaction heat, right at the spot where it is needed most. LCA comparison with petroleum-based composites was carried out.
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The objective was to characterize the properties of cellulose nanofibril/TPS based nanocomposites. The cellulose nanofibrils were extracted from wheat straw using steam explosion, acidic treatment and high shear mechanical treatment. These nanofibrils were dispersed in thermo plastic starch (TPS) using a Fluko high shear mixer in varying proportions and films were casted out of these nanocomposites. The cellulose nanofibrils were characterized using AFM, TEM, SEM, TGA, FTIR and WAXRD and the nanocomposite films were analyzed in terms of SEM, WAXRD, TGA, DSC, mechanical and barrier properties. XRD and TGA results confirmed the crystalline nature of nanofibrils. AFM and TEM images revealed fiber diameter in the range 30–70 nm. TGA depicted an increasing in residue left with increase in cellulose nanofibrils content. Mechanical properties increased with nanofiber concentration. Barrier properties also improved with addition of nanofillers up to 10% but further addition deteriorated properties due to possible fiber agglomeration.
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Polyvinyl alcohols (PVA) (CAS no. 9002-89-5) are synthetic polymers used in a wide range of industrial, commercial, medical and food applications. The purpose of this review, this critical evaluation of the available information on PVA, is to support the safety of PVA as a coating agent for pharmaceutical and dietary supplement products. All the available information on PVA gleaned from a comprehensive search of the scientific literature were critically evaluated. Orally administered PVA is relatively harmless. The safety of PVA is based on the following: (1) the acute oral toxicity of PVA is very low, with LD(50)s in the range of 15-20 g/kg; (2) orally administered PVA is very poorly absorbed from the gastrointestinal tract; (3) PVA does not accumulate in the body when administered orally; (4) PVA is not mutagenic or clastogenic; and (5) NOAELs of orally administered PVA in male and female rats were 5000 mg/kg body weight/day in the 90-day dietary study and 5000 mg/kg body weight/day in the two-generation reproduction study, which was the highest dose tested. A critical evaluation of the existing information on PVA supports its safety for use as a coating agent for pharmaceutical and dietary supplement products.
Recycled newspaper cellulose fiber (RNCF) reinforced poly(lactic acid) (PLA) biocomposites were fabricated by a microcompounding and molding system. RNCF-reinforced polypropylene (PP) composites were also processed with a recycled newspaper fiber content of 30 wt % and were compared to PLA/RNCF composites. The mechanical and thermal−mechanical properties of these composites have been studied and compared to PLA/talc and PP/talc composites. These composites possess similar mechanical properties to talc-filled composites as a result of reinforcement by RNCF. The tensile and flexural modulus of the biocomposites was significantly higher when compared with the virgin resin. The tensile modulus (6.3 GPa) of the PLA/RNCF composite (30 wt % fiber content) was comparable to that of traditional (i.e. polypropylene/talc) composites. The DMA storage modulus and the loss modulus of the RNCF−PLA composites were found to increase, whereas the mechanical loss factor (tan δ) was found to decrease. Differential scanning calorimetry (DSC) thermograms of neat PLA and of the composites exhibit nearly the same glass transition temperatures and melting temperatures. The morphology evaluated by scanning electron microscopy (SEM) indicated good dispersion of RNCF in the PLA matrix. Thermogravimetric analysis (TGA) thermograms reveal the thermal stability of the biocomposites to nearly 350 °C. These findings illustrate that RNCF possesses good thermal properties, compares favorably with talc filler in mechanical properties, and could be a good alternative reinforcement fiber for biopolymer composites.
“Green”/biobased composites were prepared from poly(lactic acid) (PLA) and recycled cellulose fibers (from newsprint) by extrusion followed by injection molding processing. The physico-mechanical and morphological properties of the composites were investigated as a function of varying amounts of cellulose fibers. Compared to the neat resin, the tensile and flexural moduli of the composites were significantly higher. This is due to higher modulus of the reinforcement added to the PLA matrix. Dynamic mechanical analysis (DMA) results also confirmed that the storage modulus of PLA increased on reinforcements with cellulose fibers indicating the stress transfers from the matrix resin to cellulose fiber. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the presence of cellulose fibers did not significantly affect the crystallinity, or the thermal decomposition of PLA matrix up to 30 wt% cellulose fiber content. Overall it was concluded that recycled cellulose fibers from newsprint could be a potential reinforcement for the high performance biodegradable polymer composites.
Natural/bio-fibers are replacing synthetic reinforcements traditionally used for the preparation of the environmentally friendly composites. Composite materials are also replacing conventional materials in various fields due to their ease of processability. Chopped glass fiber- and recycled newspaper cellulose fiber (RNCF)- reinforced poly(lactic acid) (PLA) composites were processed using a full size twin-screw extruder and an injection molder. Additionally, a glass-reinforced polypropylene (PP) composite was compounded and molded, and compared to PLA/RNCF and PLA/glass fiber composites. The tensile and flexural moduli of RNCF- reinforced composites were significantly higher when compared to the virgin resin. The morphology, evaluated by scanning electron microscopy, indicated uniform dispersion of both fibers in the PLA matrix. The mechanical and thermo-physical properties of PLA/RNCF, PLA/glass and PP/glass fiber composite were studied and compared using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). DMA results confirmed that the storage and loss moduli of the PLA/RNCF composites increased with respect to the pure polymer, whereas the mechanical loss factor (tan delta) decreased. The results of the TGA experiments indicated that the addition of fibers increased the thermal stability of the biocomposites compared to neat PLA. The heat defection temperature of PLA/RNCF was found to be comparable to that of the glass fiber-reinforced PLA composites. Such studies are of great interest in the development of environmentally friendly composites from biodegradable polymers.
The paper describes the production and the mechanical characteristics of composites made completely of renewable raw materials. Composites of different kinds of natural fibres like cotton, hemp, kenaf and man-made cellulose fibres (Lyocell) with various characteristics were processed with a fibre mass proportion of 40% and poly(lactic acid) (PLA) by compression moulding. Additionally, composites were made of fibre mixtures (hemp/kenaf, hemp/Lyocell). The composites were tested for tensile strength, elongation at break, Young’s modulus and Charpy impact strength. Their characteristics varied markedly depending on the characteristics of the raw fibres and fibre bundles and fibre mixtures used. While kenaf and hemp/PLA composites showed very high tensile strength and Young’s modulus values, cotton/PLA showed good impact characteristics. Lyocell/PLA composites combined both, high tensile strength and Young’s modulus with high impact strength. Thus, the composites could be applied in various fields, each meeting different requirements.
The focus of this work is to study the influence of mechanochemical treatment of cellulose on the physicochemical properties of its polyvinyl alcohol (PVA) composites. Cellulose fibers subjected to pan-milling could be mechanochemically activated by breaking up the intra- and inter-molecular hydrogen bonds through shearing and compressing forces. Reactive hydroxyl groups were exposed on the cellulose surface, which could establish new hydrogen bonds with PVA. Moreover, the simultaneous reduction of particle size and large increment of specific surface area of pan-milled cellulose would benefit its dispersion as well as the interfacial adhesion with polymer matrix. PVA/cellulose composites were successfully processed by the melt in the presence of plasticizers containing formamide and water. Tensile tests demonstrated positive results from mechanochemical treatment. As pan-milling cycles of cellulose increased, the tensile strength of PVA/cellulose composites increased from 8.8 MPa to 16.4 MPa, while elongation at break increased from 76.8% to 374%. The composite materials also exhibited enhanced thermal stability and better biodegradability.
The degradation of polyvinyl alcohol (PVA) by gamma-ray irradiation was investigated. Degradation efficiency of PVA was influenced by several factors, such as initial PVA concentration, dose rate, pH, and the addition of H2O2. The degradation kinetics depended on initial PVA concentration and dose rate. At a relatively lower PVA concentration, e.g., 180 mg/L, and a higher dose rate, e.g., 55.7 Gy/min, the degradation followed pseudo-first-order kinetics. On the contrary, at a higher PVA concentration, e.g., 500 mg/L, but a lower dose rate, e.g., 12.1 Gy/min, a pseudo-zero-order reaction occurred. The removal of PVA was more effective under acidic or alkaline conditions than that under neutral conditions. At a certain dose rate there was an optimal dosage of H2O2 to facilitate the degradation of PVA. For instance, at a dose rate of 17.2 Gy/min, the optimal H2O2 dosage was found to be about 2.5 mmol/L. Radical scavenging experiments, total organic carbon determination, and FTIR analysis on the degradation products demonstrated that PVA radiolysis was initiated by *OH and H*, leading to chain scission and formation of ketones/enols. Ultimately, complete mineralization of PVA was achieved.