-
Accepted Manuscript
Application of waste poly(ethylene terephthalate) in the
synthesis of new oligomericplasticizers
Ewa Langer, Sylwia Wakiewicz, Marta Lenartowicz-Klik, Krzysztof
Bortel
PII: S0141-3910(15)00168-8
DOI: 10.1016/j.polymdegradstab.2015.04.031
Reference: PDST 7645
To appear in: Polymer Degradation and Stability
Received Date: 27 January 2015
Revised Date: 24 April 2015
Accepted Date: 29 April 2015
Please cite this article as: Langer E, Wakiewicz S,
Lenartowicz-Klik M, Bortel K, Application of wastepoly(ethylene
terephthalate) in the synthesis of new oligomeric plasticizers,
Polymer Degradation andStability (2015), doi:
10.1016/j.polymdegradstab.2015.04.031.
This is a PDF file of an unedited manuscript that has been
accepted for publication. As a service toour customers we are
providing this early version of the manuscript. The manuscript will
undergocopyediting, typesetting, and review of the resulting proof
before it is published in its final form. Pleasenote that during
the production process errors may be discovered which could affect
the content, and alllegal disclaimers that apply to the journal
pertain.
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
1
Application of waste poly(ethylene terephthalate) in the
synthesis of new
oligomeric plasticizers
Ewa Langera, Sylwia Wakiewiczb, Marta Lenartowicz-Klika,
Krzysztof Bortela
aInstitute for Engineering of Polymer Materials and Dyes, 87-100
Toru, ul. M.
Skodowskiej-Curie 55, Poland, e-mail: [email protected]
bSilesian University of Technology, Faculty of Chemistry, 44-100
Gliwice, ul. Strzody 9,
Poland
Keywords: chemical recycling, poly(ethylene terephthalate)
waste, oligomeric plasticizer
ABSTRACT
New method of trensesterification of waste poly(ethylene
terephthalate) (PET) with aliphatic
oligoesters was developed. The structures of obtained
oligoesters were identified by NMR,
ESI-MS and SEC methods, and then correlated with physical
properties determined by DSC
and TGA analyses. Physico-chemical properties of synthesized
plasticizers were compared
with monomeric and polymeric commercial products. Products of
the reaction of PET with
oligoesters based on azelaic acid with 1.4-butanediol and adipic
acid with triethylene glycol
occurred to be remarkable substitutes of commercial
plasticizers. They possessed lower
volatility and much higher thermal stability. Insertion of
glycerol unit into aliphatic oligoester
and using it for the process of PET depolymerization resulted in
obtaining of plasticizers of
branching structure with glycerol unit as a core. They possessed
lower viscosity and higher
molecular mass in comparison with their linear equivalents.
1. Introduction
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
2
Poly(ethylene terephthalate) (PET) is one of the most commonly
used engineering plastics
which owes its popularity to its mechanical properties, chemical
resistance, clarity, low O2
and H2O permeability, and good rigidity/weight ratio. The use of
poly(ethylene terephthalate)
has increased significantly in recent years since its
introduction as a material for the
production of beverage packaging. Moreover, it is widely used in
the textile industry, high
strength fibres and photographic films. PET itself is not
directly hazardous for the natural
environment but it does make up a considerable volume of all the
municipal waste ending up
in landfills. It does not erode due to its high resistance to
weathering and biological agents.
PET is a non-degradable plastic in normal conditions, as there
is no known organism that can
consume its relatively large molecules [1]. However PET is one
of the most extensively
recycled polymeric materials.
There are three distinct approaches to the recycling of
post-consumer plastic packaging
materials. The Environmental Protection Agency (EPA) has adopted
a new extensive
nomenclature that refers to physical reprocessing as secondary
recycling (2) and chemical
processing as tertiary recycling (3). The EPA primary recycling
(1) refers to the use of pre-
consumer industrial scrap and salvage to form new packaging, a
common product in industry
[2].
There are numerous chemical ways of recycling PET, which
include: hydrolysis, alcoholysis,
aminolysis, acidolysis, glycolysis and transesterification. PET
is chemically re-processed by
its total depolymerization into monomers or partial
depolymerization into oligomers and other
products [3]. Table 1 presents the chemical methods of chemical
recycling of PET, the main
reactants and the products obtained [4-8].
Table 1. Methods of chemical recycling of PET
Method Reactant Reaction products
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
3
Hydrolysis Water Terephthalic acid and ethylene glycol
Alcoholysis Methanol Dimethyl terephthalate and ethylene glycol
(1.2-ethane diol)
Aminolysis Amine Terephthalamide Glycolysis Ethylene glycol
Bishydroxyethyl terephthalate
and ethylene glycol
The utilization of PET waste generates value-added products such
as unsaturated polyester
resins, oligo- or polyester plasticizers, acrylate/methacrylate
terminated oligoesters and raw
materials for polyurethanes [5-8]. Our study focused on
oligoester plasticizers obtained by
means of the chemical recycling of PET.
The most commonly used plasticizers are monomeric plasticizers,
such as: phthalates,
adipates and benzoates. Their disadvantages include lower
resistance of the bond line to heat
and possible migration. However, the use of phthalic
plasticizers has been on the decrease due
to their toxicity and tendency to sweat out. Some companies and
sectors have looked for safer
materials as alternatives to certain phthalates. While
oligomeric plasticizers have smaller
plasticizing ability compared to monomeric plasticizers, they
exhibit limited volatility and
migration and do not undergo extraction, which is essential in
many applications [9].
There are many publications in the literature on obtaining
dioctyl terephthalate (DOTP) in the
process of PET alcoholysis. There are few studies, however, that
describe the synthesis of
oligomeric plasticizers based on the products of PET waste
depolymerisation. For instance,
Dupont et al. [10] reported on the alcoholysis of PET scrap
using 2-ethyl-1-hexanol (EH) at
reflux temperature for the purpose of synthesizing DOTP
plasticizers for flexible poly(vinyl
chloride) (PVC). The DOTP produced by this method was equivalent
to commercial grades in
terms of its plasticization efficiency for PVC.
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
4
Dutt and Soni, on the other hand, synthesized an oligomeric
plasticizer with an average
molecular mass in the range of 450-900 g/mol from PET waste also
through alcoholysis using
EH. They used it in nitrile rubber and nitryle-PVC blends
[11].
The boiling point of EH at atmospheric pressure is about 180 C
and the efficiency of
alcoholysis is very low. Three methods for improving the
efficiency of alcoholysis are known:
use of sub- and supercritical EH, use of transesterification
catalyst and/or addition of some
cosolvents [12].
The use of a cosolvent is a new way to accelerate the chemical
reaction and it also improves
reaction efficiency. The imidazole ionic liquid assisted in the
process of PET alcoholysis with
EH, as a cosolvent in obtaining DOTP. This process was catalyzed
by the addition of 1.2%
(w/w) of zinc acetate. The yield of DOTP reached 93% at reflux
temperature and a reaction
time of 5 h, while the weight ratio of the ionic liquid:EH:PET
was 2:2:1. The reaction time of
traditional reflux temperature alcoholysis of PET without ionic
liquid as a cosolvent should be
at least 10 h.
Oligoester plasticizers, with hydroxyl end-groups and an average
molecular mass of 2500
g/mol, were also obtained by the degradation of PET waste by
polyethylene glycol 400 and
adipic acid in the presence of a transesterification catalyst.
These compounds were tested as
plasticizers in a poly(vinyl acetate) dispersion adhesives for
flooring applications. The
samples containing synthesized plasticizers were more flexible
and had a higher thermal
stability in comparison to commercial plasticizer
1.2.3-triacetoxypropane [13].
In recent years, the following compounds have been used as
catalysts for the glycolysis or
transesterification of PET: metal acetates [14-15], phosphates
[16], solid super-acid, metal
oxide [17-18], carbonate [19], sulfate [20] and ionic
liquids.
In chemical synthesis organotin compounds are used expecially in
the esterification and
transesterification reactions of mono- and polyesters. Organotin
compounds such as
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
5
butylstannoic acid are used as catalyst to reduce the formation
of unwanted by-products and
also provide the required colour properties [21].
The aim of the presented work was the full replacement of the
low molecular weight toxic
phthalate-based plasticizers for PVC, which have been used so
far, with environmentally
friendly materials. The paper presents a new, previously
unexplored method for obtaining
oligomeric plasticisers in a reaction of PET waste
transesterification by means of oligoesters.
2. Experimental
2.1. Materials
A sample of PET flakes was acquired from Industrie Maurizio
Peruzzo POLOWAT Sp. z o.o.
(average molecular weight 50000 g/mol). Anhydrous
2-ethylhexanol, adipic acid (Ad), azelaic
acid (Az), diethylene glycol (DE), dipropylene glycol (DP),
1.4-butandiol (BD), triethylene
glycol (TE) and glycerine (Gl) were purchased from Brenntag
Polska. All reagents were used
as purchased without further purification. Fascat 4100,
butylstannoic acid, was used as a
catalyst.
2.2. Transesterification of PET
Waste PET-based plasticiser synthesis was conducted in two
stages. A 1000 ml glass reactor
equipped with an agitator, a splash-head, a thermometer and an
azeotropic cap was filled with
dicarboxylic acid, glycol and monohydroxyl alcohol (Table 2).
The reaction was carried out in
a temperature range of 140160 C under atmospheric pressure. The
reaction was carried out
until an acid value of less than 10 mgKOH/g was achieved. PET
waste and 0.06% w/w of the
Fascat 4100 esterification catalyst was added in situ to the
oligoester obtained. The
temperature of the reaction was increased to 190-210 C. The
total time of the synthesis was
10-12 hours.
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
6
The following plasticisers were obtained in the oligoester
degradation of PET waste:
azelaic acid with diethylene glycol and a 2-ethylhexanol
end-group (designated as
PETDEAz);
adipic acid with dipropylene glycol and a 2-ethylhexanol
end-group (designated as
PETDPAd);
azelaic acid with dipropylene glycol and a 2-ethylhexanol
end-group (designated as
PETDPAz);
adipic acid with 1.4-butanediol and a 2-ethylhexanol end-group
(designated as
PETBDAd);
azelaic acid with 1.4-butanediol and a 2-ethylhexanol end-group
(designated as
PETBDAz);
adipic acid with glycerine and dipropylene glycol and a
2-ethylhexanol end-group
(designated as PETDPAdGl);
azelaic acid with glycerine and dipropylene glycol and a
2-ethylhexanol end-group
(designated as PETDPAzGl);
azelaic acid with glycerine and glycol and a 2-ethylhexanol
end-group (designated as
PETDEAzGl);
The obtained products were characterized using NMR spectroscopy,
ESI-MS and SEC
spectrometry techniques, thermal analyses (DSC, TGA) and were
checked for volatility.
Table 2. Composition of synthesized plasticizers*
Symbol Composition
PETD
EAz
PETD
PAd PETD
PAz
PETB
DAd PETB
DAz
PETD
PAdGl PETD
PAzGl PETD
EAzGl
PET (g) 30.20 31.61 28.90 34.08 31.00 24.64 22.24 23.00
2-ethylhexanol (g) 13.70 14.27 13.10 15.39 13.99 16.69 15.07
15.58
Adipic acid (g) - 32.05 - 34.55 - 37.52 - - Azelaic acid (g)
39.40 - 37.80 - 40.47 - 43.59 45.05
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
7
Glycerine (g) - - - - - 3.94 3.55 3.67 Dipropylene glycol
(g) - 22.06 20.20 - - 17.22 15.54 -
Diethylene glycol
(g) 16.70 - - - - - - 12.70
1.4-butanediol (g) - - - 15.98 14.53 - - - * the reactant
amounts provided have been calculated per 100g of reactant load
2.3. Characterization of the transesterification products
Nuclear Magnetic Resonance (NMR) spectra were recorded using a
UNITY/INOVA 300
MHz (Varian Associates Inc.) multinuclear NMR spectrometer. 1H
and 13C NMR spectra
were run in deuterated chloroform (CDCl3) using
tetramethylsilane (TMS) as an internal
standard.
Differential scanning calorimetry (DSC) analyses were carried
out using a DSC 2010 Thermal
Analysis Calorimeter. Measurements and calibration were carried
out at a heating rate of 10
C/min in a nitrogen atmosphere.
The decomposition temperature of the plasticisers was determined
on the basis of the TGA
(Thermogravimetry) analysis according to EN ISO
11358:2004Plastics -
Thermogravimetry (TG) of polymers - General principles. Samples
were heated at a rate of
20 C/min from 25 C to 900 C under nitrogen atmosphere.
Electrospray ionisation mass spectrometry (ESI-MS) experiments
were performed using an
AmaZon (Bruker-Daltonics, Brema, Germany) mass spectrometer
equipped with an
electrospray ionisation source. Samples were dissolved in a
solution of CHCl3/methanol ((v/v)
1:1). The mass spectrum was acquired over the range of m/z
503000 in the positive ion
mode.
Molecular weight was measured by means of size exclusion
chromatography analysis (SEC)
using a Waters system equipped with refractive index detector.
Two 300x7.5 mm (Polymer
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
8
Laboratories VARIAN) Pl-gel m Mixed C columns were used and
maintained at 40 C.
Fisher Chemicals tetrahydrofuran (THF) was used as eluent at a
flow rate of 1 mL/min.
Polystyrene standards (Polymer Laboratories) were used to
calibrate the system.
The viscosity of the plasticizers was determined in accordance
with ISO 2555.
The volatility of the plasticizers was determined by the authors
own method. Volatility was
determined by placing the samples of the tested plasticisers in
petri dishes in a drier without
air circulation for 2 h at temperatures of 160 to 180 C, and the
obtained values (expressed in
%) were calculated on the basis of the mass loss of the
sample.
3. Results and discussion
Oligoester plasticizers were obtained in a 2-step reaction. The
first stage consisted of the
synthesis of oligoesters from dicarboxylic acid (adipic or
azelaic acid), glycol (diethylene,
dipropylene or 1.4-butanediol glycol) and 2-ethylhexanol. It was
conducted until an acid
value of less than 10 mgKOH/g was achieved. The second stage, on
the other hand, involved
the transesterification of waste PET using the previously
synthesised oligoester using the
Fascat 4100 catalyst (Fig. 1) until a hydroxyl and acid value of
less than 10 mg KOH/g was
achieved. This made it possible to assume that the oligoesters
obtained had 2-ethylhexanol
ends on both sides.
Fascat 4100 (butylstannoic acid, BuSn(O)OH) is insoluble solid
in a series of solvents and is
categorized as stable oligomeric structure at room temperature.
However, on increasing the
temperature these particular arrangements can be destabilized,
resulting in more active
molecular species [22]. One of the main advantages of this
catalyst is lack of necessity of
neutralization or filtration at the end of reaction. Besides it
provides energy savings with
lower reaction temperatures.
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
9
According to literature data, transesterification mechanism
using Lewis acid catalysts, the
acid site (in this case free tin orbital) is joining the oxygen
of the carbonyl group, increasing
the electrophilicity of the adjoining carbon atom and making it
more susceptible to nucleofilic
attack [23]. For this reason depolymerisation of PET chains via
transesterification reaction
using oligoesters tipped with 2-ethylhexanol takes place.
HOCRCOHO O
+ 34 HOR'OH + 2 OH
3
OOCRCOCRCOR'OOO O
+
CO
COCH2CH2OO
n
Fascat 4100
products of transesterification
stage 1
stage 2
Fig. 1. Scheme of obtaining of linear oligoesters of PET
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
10
HOCRCOHO O
+ 912 HOR'OH + 3 OH
CO
COCH2CH2OO
n
Fascat 4100
products of transesterification
stage 1
stage 2
HO OHOH
+
C ORC OOR'
C OR
OC O
O
OCRCO O O O
OR'OCRCOCRCOR'O
OOO
O OCRCOO
3 3
+
3
Fig. 2. Scheme of obtaining of branched oligoesters of PET
On the basis of an analysis of 1H NMR (Fig. 3-4) and 13C NMR
(Fig. 5-6) spectra it is
confirmed that both the anticipated reactions, i.e. the
synthesis of oligoesters and
transesterification, occurred. This is revealed by the fact that
no free function groups, i.e.
neither hydroxyl nor carboxyl groups, were present. In
plasticisers, glycols can connect on
both sides with dicarboxylic acid, on both sides with
terephthalic acid (TA) or simultaneously
with dicarboxylic and terephthalic acid. All these combinations
were observed in 1H NMR
spectra in the range of 3.25-5.50 ppm and in 13C NMR spectra in
the range of 60-75 ppm
which were characteristic for the protons and atoms of the
carbons of groups -CH2-O-, >CH-
O- respectively in different chemical environments. In addition,
the structures of the
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
11
compounds found in the mixture created in the reaction were
confirmed through an ESI-MS
analysis. The NMR analysis is an important tool in the study of
the structure of the oligomer
chain but only an ESI-MS investigation can determine the subtle
differences in the chemical
structure. These spectra clearly indicate that a statistically
significant transesterification
reaction took place, where the PET chains have chemically
degraded into fragments of
different lengths.
Fig. 3. 1H NMR (CDCl3, 300 MHz) spectra of a) oligoester DPAz
and b) products of
transesterification of PET with DPAz (PETDPAz)
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
12
Fig. 4. 1H NMR (CDCl3, 300 MHz) spectra of a) oligoester DEAzGl
and b) products of
transesterification of PET with DEAzGl (PETDEAzGl)
77.16 Chloroform-d
Fig. 5. 13C NMR (CDCl3, 75 MHz) spectrum of products of
transesterification of PET with
DPAz (PETDPAz)
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
13
Fig. 6. 13C NMR (CDCl3, 75 MHz) spectrum of products of
transesterification of PET with
DEAzGl (PETDEAzGl)
On the basis of an analysis of a sample ESI-MS spectrum of a
PETDPAz specimen (Fig. 7), it
was found that the plasticizers had 2-ethylhexanol connected
with azelaic acid at their ends
(m/z= 721.3, 961.5, 1100.7, 1261.1, 1699.6 and 1999.8) or longer
fragments of oligoester (-
Az-DP-) obtained in the first stage of the synthesis (m/z =
1482.3, 2156.6 and 2306.4), where
a -TA-GE-TA- fragment constituted the core. The presence of DE
(m/z = 1261.1 and 1699.6)
is the result of an ethylene glycol (EG) reaction taking place,
an important side reaction in
PET synthesis [24].
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
14
Fig. 7. ESI-MS spectra of PETDPAz
In the case of the introduction of glycerine, i.e. an additional
reactant into the esterification
reaction, a regularity was observed, which differentiated these
branched out plasticiser
molecules from the previously discussed linear molecules (Fig.
8). Namely, one glycerine unit
constituted the core of a plasticizer molecule, which connected
directly with a unit of TA. The
further structure of the individual arms of the oligoester
branching out from the glycerine
molecule is akin to forms created in the linear
plasticisers.
Fig. 8. ESI-MS spectra of PETDEAzGl
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
15
Table 3. The results of a gel chromatography analysis of the
plasticizers obtained
Symbol Number average molecular weight
Mn (g/mol)
Weight average molecular weight
Mw (g/mol) Dispersity
PETDEAz 1430 2500 1.75 PETDPAd 1530 2780 1.82 PETDPAz 1420 2600
1.83 PETBDAd 1610 2730 1.70 PETBDAz 1900 3400 1.80
PETDPAdGl 1590 3830 2.41 PETDPAzGl 1650 3950 2.39 PETDEAzGl 1670
3920 2.34
PETTEAd 1520 2780 1.83 H-1 2270 4230 1.87
The SEC analysis also leads to the conclusion that the
degradation of waste PET occurred by
transesterification reaction, leading to the formation of the
anticipated products - oligoesters
with TA-EG- units embedded in their structure. In weight terms,
the average molecular
weight in the case of linear oligoesters ranged from 2500 to
3400 g/mol, and their dispersity
ranged from 1.70 to 1.83. However, in the case of branched
oligoesters, these values ranged
from 3830 to 3950 g/mol and 2.34 to 2.41 respectively. It was
found that adding glycerine to
the synthesis as a reactant caused adverse effects as it led to
a significant increase in the
dispersion of the product in each and every case.
In Table 4, the viscosity designations of the synthesised
plasticisers and commercial,
polymeric plasticizer (H1) are presented. The viscosity of
plasticizers does not depend only
on the molecular weight, but to a large extent also on the
structure of the compound obtained
and the raw materials used in the synthesis. Lower viscosity
levels are observed in products
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
16
having a branched structure, which were synthesised using
glycerine. Longer aliphatic chains
produce a lower viscosity. By using the same glycols, a lower
viscosity was observed in
plasticizers with azelaic acid than with adipic acid.
Table 4. Viscosities of the plasticizers obtained
Symbol Viscosity (mPas)
PETDEAz 13 000
PETDPAd 23 500 PETDPAz 10 700
PETBDAd 30 500 PETBDAz 27 500
PETDPAdGl 9 000 PETDPAzGl 9 500 PETDEAzGl 8 750
PETTEAd 9 600 H-1 6 750
The volatility of oligoesters at temperatures of 160, 170, 180 C
was determined. In
characterising plasticisers, their volatility, particularly at
higher temperatures, is an important
parameter. Taking into account the processing temperature of
plasticised PVC compositions,
it is required that the plasticizers present as low a volatility
as possible, due to the possible
loss of the plasticizer during the process as well as its escape
into the environment. In
addition, the high volatility of the plasticiser makes
plasticised products lose their properties
during use particularly in high temperature environments. For
all the synthesised oligoesters,
the volatility values were lower compared to the volatility of
the monomeric DEHP
plasticiser. At a temperature of 180 C in particular, the
difference between the synthesised
products and a monomeric commercial product is significant.
PETTEAd and PETBDAz
oligoesters have a volatility of 1% at this temperature. The
higher volatility values of
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
17
branched oligoesters containing glycerine correspond to higher
dispersion values compared to
linear products. It is observed that the dispersion value also
has an influence on the thermal
stability of oligoesters. This general tendency, along with an
increase in dispersion, leads to a
decrease in thermal stability, which corresponds to a lower
temperature at which a given mass
loss occurs (Fig. 9).
Fig. 9. Plasticiser mass loss versus temperature
Table 5. Decomposition temperature and glass transition
temperature (Tg) of the obtained plasticisers
Composition Decomposition temperature (C) Tg (C) PETDEAz 431.0
-44.6 PETDPAd 444.1 -47.3 PETDPAz 381.2 -45.8 PETBDAd 423.6 -46.2
PETBDAz 421.1 -51.1
PETDPAdGl 418.6 -45.5 PETDPAzGl 410.3 -48.2
PETDEAzGl 445.8 -43.6 PETTEAd 398.9 -45.3
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
18
H1 379.3 -49.4
The glass transition temperatures of the obtained plasticisers
compared to the commercial
varieties are similar and range from -43.6 to -51.1 C.
When comparing the decomposition temperatures of the obtained
oligoesters with those of the
commercial plasticiser it was found that these compounds have a
much higher thermal
stability. Only PETDPAz has a decomposition temperature which is
similar to that of the
polymeric commercial plasticiser. As shown in the diagram (Fig.
10) the mass loss curve is
also similar. The plasticiser samples containing glycerine
revealed a much higher
decomposition temperature compared to its analogue varieties
without glycerine.
Fig. 10. Volatility of synthesised oligoesters compared to that
of commercial plasticisers
4. Conclusions
The research results proved that it is possible to use waste PET
for the synthesis of new
oligoesters, which can be used as plasticisers. Taking into
consideration the general
characteristics of each sample of the synthesised plasticiser
and comparing them with
monomeric and polymeric commercial products, PETBDAz and PETTEAd
seem to be the
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
19
most promising. Mentioned plasticizers possessed lower
volatility and much higher thermal
stability in comparison with commercial products.
It was proved that in spite of relatively high molecular mass of
obtained plasticizers of
branching structure they possess lower viscosity in comparison
with synthesized oligoester
products of linear structure. However the disadvantage of these
products is their high
molecular-weight dispersity (above 2.3) what results in higher
volatility.
The results of tests of the useability of the synthesised
plasticisers in obtaining plasticised
PVC compositions will be presented in a later article.
References
[1] Jankauskaite V., Macijauskas G., Lygaitis R. Polyethylene
terephthalate waste recycling
and application possibilities: a review. Mater Sci
2008;14(2):119-127.
[2] Nikles D.E., Farahat M.S. New motivation for the
depolymerization products derived
from poly(ethylene terephthalate) (PET) Waste. Macromol Mater
Eng 2005;290:13-30.
[3] Firas A., Dumitru P. Recycling of PET. Eur Polym J
2005;41(7):1453-1677.
[4] Jain A., Soni R.K. Spectroscopic investigation of end
products obtained by amonolysis of
poly(ethylene terephthalate) waste in the presence of zinc
acetate as a catalyst. J Polym Res
2007;14:475-481.
[5] Tawfik M. E., Eskander S.B. Chemical recycling of
poly(ethylene terephthalate) waste
using ethanolamine. Sorting of the end products. Polym Degrad
Stab 2010;95:187-194.
[6] Imran M., Kim B.-K., Han M., Cho B.G., Kim D.H. Sub- and
supercritical glycolysis of
polyethylene terephthalate (PET) into the monomer
bis(2-hydroxyethyl) terephthalate
(BHET). Polym Degrad Stab 2010;95:1686-1693.
[7] Xi G., Lu M., Sun C. Study on depolymerization of waste
polyethylene terephthalate into
monomer of bis(2-hydroxyethyl terephthalate). Polym Degrad Stab
2005;87:117-120.
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
20
[8] Yue Q.F., Wang C.X., Zhang L.N., Ni Y., Jin Y.X. Glycolysis
of poly(ethylene
terephthalate) (PET) using basic ionic liquids as catalysts.
Polym Degrad Stab 2011;96:399-
403.
[9] Mansour S.H., Ikladious N.E. Depolymerization of
poly(ethylene terephthalate) wastes
using 1,4-butanediol and triethylene glycol. Polym Test
2002;21:497.
[10] Dupont L. A., Gupta V. P. Degradative transestryfication of
terephthalate polyesters to
obtain DOTP plasticizer for flexible PVC. J Vinyl Technol
1993;15:100.
[11] Dutt K., Soni R.K. Synthesis and characterization of
polymeric plasticizer from PET
waste and its applications in nitrile rubber and nitrile-PVC
blend. Iran Polym J 2013;22:481-
491.
[12] Chen J., Lv J., Ji Y., Ding J., Yang X., Zou M., Xing L.
Alcoholysis of PET to produce
dioctyl terephthalate by isooctyl alcohol with ionic liquid as
cosolvent. Polym Degrad Stab
2014;107:178-183.
[13] Jasiukaityte-Grojzdek E., Kunaver M., Kukanja D., Moderc D.
Renewable (waste)
material based polyesters as plasticizers for adhesives. Int J
Adhes Adhes 2013;46: 56-61.
[14] Xi G., Lu M., Sun C. Study on depolymerization of waste
polyethylene terephthalate
into monomer of bis(2-hydroxyethyl terephthalate). Polym Degrad
Stab 2005;87:117-120.
[15] Ljerka KK., Zlata HM, Jasenka J., Branka A. Evaluation of
Poly(ethylene-terephthalate)
Products of Chemical Recycling by Differential Scanning
Calorimetry. J Polym Environ
2009;17(1):20-27.
[16] Troev K., Grancharov G., Tsevi R., Gitsov I. A novel
catalyst for the glycolysis of
poly(ethylene terephthalate). J Appl Polym Sci
2003;90(4):1148-1152.
[17] Imran M., Lee KG, Imtiaz Q., Kim B., Han M., Cho BG. et al.
Metal-oxide-doped silica
nanoparticles for the catalytic glycolysis of polyethylene
terephthalate. J Nanosci
Nanotechnol 2011;11(1):824-828.
-
MAN
USCR
IPT
ACCE
PTED
ACCEPTED MANUSCRIPT
21
[18] Wi R., Imran M., Lee KG, Yoon SH, Cho BG, Kim BH. Recent
Developments in the
Chemical Recycling of PET. J Nanosci Nanotechnol 2011;11(7):
6544-6549.
[19] Shukla SR. Kulkarni KS. Depolymerization of poly(ethylene
terephthalate) waste. J
Appl Polym Sci 2002;85:1765-1770.
[20] Shukla SR, Harad AM. Glycolysis of polyethylene
terephthalate waste fibers. J Appl
Polym Sci 2005;97(2):513-517.
[21] Gioia C., Vannini M., Marchese P., Minesso A., Cavalieri
R., Colonna M., Celli A.
Sustainable polyesters for powder coating applications from
recycled PET, isosorbide and
succinic acid. Green Chem 2014;16:1807-1815.
[22] Meneghetti M.R., Plentz-Meneghetti S.M. Sn(IV)-based
organometallics as catalysts for
the production of fatty acid alkyl esters. Catal Sci Technol
2015;5:765-771.
[23] Casas A., Ramos M.J., Rodrguez J.F., Prez . Tin compounds
as Lewis acid catalysts
for esterification and transesterification of acid vegetable
oils. Fuel Process Technol 2013;
106:321-325.
[24] Chen J.-W., Chen L.-W. The kinetics of diethylene glycol
formation in the preparation
of polyethylene terephthalate. J Polym Sci: Polym Chem
1998;36:3073-3080.