New thermoplastic polyurethane elastomers based on aliphatic diisocyanate
New thermoplastic polyurethane elastomers based on aliphatic diisocyanate
Andrzej Puszka 0
Anna Kultys 0
0 Department of Polymer Chemistry, Faculty of Chemistry, Maria Curie-Skłodowska University , ul. Gliniana 33, 20-614 Lublin , Poland
New segmented polyurethanes (SPURs) were synthesized by one-step melt polyaddition from a poly (oxytetramethylene)diol of Mn = 1000 g mol-1 (PTMO) or a poly(hexamethylene carbonate)diol of Mn = 860 g mol-1 (PHCD) as soft segments, 5-isocyanato-1-(isocyanatomethyl)1,3,3-trimethylcyclohexane (IPDI), and 2,20-methylenebis [(4,1-phenylene)methylenesulfanediyl]diethanol (diol E) as an unconventional chain extender. Furthermore, some of SPURs were modified by the addition of a carboxylic group by means of 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid. The effects of the kind and amount of the polymer diol and chain extender used on the structure and properties of the polymers were studied. The polymers were examined by attenuated total reflection Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis (TG), TG-FTIR, differential scanning calorimetry (DSC), Shore A/D hardness and tensile testing. The obtained SPURs were amorphous, colourless, high molar mass materials which showed elastomeric or plastic properties. Their Tgs were in the range of -51 to 29 C. It was observed that the polymers with a PHCD demonstrated a better segmental miscibility (higher Tgs), as well as greater hardness and tensile strengths, but smaller elongations at break than PTMO-based ones. All of the polymers exhibited a relatively good thermal stability.
Sulphur-containing polyurethanes; Amorphous polymers; DSC; Thermogravimetric analysis; Mechanical properties; Carboxylate polymers
Polyurethane elastomers are a very interesting type of
polyurethane materials. They are now widely used due to
their unique properties, such as an outstanding mechanical
strength, good chemical resistance and excellent elasticity.
In recent years, the importance of thermoplastic
polyurethane elastomers (TPUs) has grown as a result of a less
complicated and less expensive production process
compared to vulcanized elastomers as well as the possibility of
their recycling. TPUs are polymers that show properties
characteristic of elastomers in the normal conditions of use
getting plasticized when heated. This means that they may
be processed using methods typical of thermoplastics, i.e.
extrusion, calendaring or injection [1–3].
Typical TPUs are multiblock copolymers consisting of
alternating flexible ‘‘soft’’ segments derived from aliphatic
linear polymer diols and ‘‘hard’’ segments formed from
diisocyanates and short-chain diols.
TPUs are polyaddition reaction products involving
aromatic (mainly 1,10-methylenebis (4-isocyanatobenzene)
(MDI)) or aliphatic diisocyanates (predominantly
1,10methylenebis (4-isocyanatocyclohexane) (HMDI) and
1,6diisocyanatohexane (HDI)), aliphatic linear polymer diols
(polyetherdiols, polyesterdiols or polycarbonate diols) as
well as the chain extenders (usually butane-1,4-diol),
which in the case of less reactive substrates require the
presence of a catalyst [1–3].
Aromatic diisocyanate-based TPUs generally bear
superior mechanical properties due to a strong cohesion force
between the hard segment chains. However, the aromatic
diisocyanate-based TPUs possess serious defects, such as
change of colour or decrease in thermal and mechanical
properties against ultraviolet and visible light and heat
[1, 3, 4]. In contrast, the aliphatic diisocyanate-based TPUs
show no change of colour in the same condition .
This paper is a continuation of research on the new
TPUs derived from aliphatic–aromatic sulphur-containing
chain extenders as well as derivatives of diphenylmethane
[5–13], diphenylethane [14–16], benzophenone [17–19],
diphenyl ether  and diphenyl sulphide [21, 22]. Based
on the test results, it can be concluded that the introduction
of sulphur atoms into the structure of a polymer has
increased their adhesive strength  and refractive index
[11, 12]. In addition, antibacterial properties against
grampositive bacteria were indicated .
In this work, we present both a synthesis and
5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane (IPDI)-based segmented polyurethanes (SPURs)
with polyether and polycarbonate soft segments, i.e. poly
(oxytetramethylene)diol of Mn = 1000 g mol-1 (PTMO) or
poly(hexamethylene carbonate)diol of Mn = 860 g mol-1
(PHCD) and an unconventional chain extender, i.e.
(diol E). The content of hard segments was contained within
30–60 mass%. Additionally, SPURs with the hard content of
50 mass% were modified by the addition of a carboxylic
group by means of
3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid (DMPA). Because the newly obtained SPURs
incorporate sulphur atoms in their structure, they can exhibit
improved antimicrobial activity as well as both optical and
adhesive properties [23, 24]. On the other hand, the
introduction of functional groups into the polymer structure, such
as sulphonic and carboxylic ones, makes it possible to
improve the biocompatibility of these materials and therefore
apply them in the production of various medical appliances
[25, 26]. Additionally, their presence makes it possible to
obtain ionomers that can be applied in the production of, inter
alia, coating materials [25–31].
This work also gives a characterization of the newly
obtained regular polyurethane (R-PUR) based on IPDI and
diol E, building the hard segment in TPUs.
The diol E (m.p. = 77–78 C) was obtained by the
condensation reaction of
[methylenedi(4,1-phenylene)]dimethanethiol with 2-chloroethanol in 10 % aqueous
solution of sodium hydroxide . PTMO and PHCD were
purchased from Sigma-Aldrich (St. Louis, USA). Before
being used, the PTMO and PHCD were heated at 90 C in
vacuo for 10 h. IPDI and dibutyltin dilaurate (DBTDL)
from Merck Schuchardt (Hohenbrunn, Germany) and
DMPA from Sigma-Aldrich (Steinheim, Germany) were
used as received. The polymerization solvent,
N,Ndimethylformamide (DMF), with a water content of less
than 0.01 %, was purchased from Sigma-Aldrich
(Steinheim, Germany) and was used as received.
Attenuated total reflection–Fourier transform infrared
(ATR–FTIR) spectra were obtained with a FTIR TENSOR
27 (Bruker, Germany) spectrophotometer using thin films
or powder (for R-PUR). Spectra were recorded from 4000
to 600 cm-1 averaging 32 scans with a resolution of
Elemental analysis was performed with a PerkinElmer
CHN 2400 analyser (Norwalk, USA).
Reduced viscosities (gred, dL g-1) of 0.5 % polymer
solution in 1,1,2,2-tetrachloroethane (TChE) were
measured in an Ubbelohde viscometer (Gliwice, Poland) at
The number (Mn) and mass (Mw) average molar mass
(g mol-1), and the molar mass dispersity (ÐM, ÐM = Mw/
Mn) of the segmented polyurethanes were determined by
gel permeation chromatography (GPC) performed on a
Viscotek GPCMax (USA) equipped with triple detector
array TDA305. The eluent was tetrahydrofuran (THF), the
flow rate was 1 mL min-1, the operation temperature was
set to be 35 C, and the molar mass was calibrated with
The content of carboxylic group of the carboxylate
SPURs was determined by acid–base titration as follows. A
given mass (about 3 g) of the sample was dissolved in
200 cm3 of hot DMF, and two drops of phenolphthalein
solution as indicator were added with agitation. The
resulting solution was titrated with 0.1 M KOH in
Thermogravimetric analysis (TG) was performed on a
MOM 3 427 derivatograph (Paulik, Paulik and Erdey,
Budapest, Hungary) in the range of 20–1000 C in air
atmosphere, at the heating rate of 10 C min-1. All TG
measurements were taken in Al2O3. As a reference, empty
Al2O3 crucible was applied. Sample masses about 100 mg
TG–FTIR was carried out with a Netzsch STA 449 F1
Jupiter thermal analyser (Germany). In a typical procedure,
ca. 10 mg of the sample was heated from 40 up to 700 C
with a heating rate of 10 C min-1 in open Al2O3 crucible
(mass of 160 ± 1 mg) under inert conditions (helium, flow
rate 20 mL min-1). As a reference, empty Al2O3 crucible
was applied. The composition of the gas evolved during the
decomposition process was analysed by a Bruker Tensor 27
FTIR spectrometer (Germany) coupled online to a Netzsch
STA instrument by Teflon transfer line with 2 mm
diameter heated to 200 C. The FTIR spectra were recorded in
the spectral range of 600–4000 cm-1 with 16 scans per
spectrum at 4 cm-1 resolution.
Differential scanning calorimetry (DSC) experiments
were performed with a Netzsch 204 calorimeter (Germany).
All DSC measurements were taken in aluminium pans with
pierced lid (mass of 40 ± 1 mg). As a reference, empty
aluminium crucible was applied. Sample masses of about
10 mg were used. The sample pan was placed in the
calorimeter at *25 C and then subjected to the following
time–temperature program: (1) cooling and isotherm for
3 min at -100 C; (2) heating to 200 C; (3) cooling to
-100 C; and (4) heating to 200 C. The reported transitions
were taken from first and second heating scans. The scans
were performed at the heating/cooling rate of 10 C min-1
under nitrogen atmosphere (flow = 30 cm3 min-1). Glass
transition temperatures (Tgs) for the polymer samples were
taken as the inflection point on the curves of the heat capacity
The hardness of the SPURs was measured by the Shore
A/D method on a Zwick 7206/H04 hardness tester
(Germany) at 23 C. The values were taken after 15 s.
Tensile testing was performed on a Zwick/Roell Z010
tensile testing machine (Germany) according to Polish
Standard PN-81/C-89034 at the speed of 100 mm min-1 at
23 C; the tensile test pieces 1 mm thick and 6 mm wide
(for the section measured) were cut from the pressed sheet.
Press moulding was done with a Carver hydraulic press
(USA) at 120–160 C under 10–30 MPa pressure.
R-PUR was prepared by the solution polymerization of an
equimolar amount (0.01 mol) of diol E and IPDI (DMF,
concentration *20 mass%); this was carried out under dry
nitrogen for 4 h at 85 C in the presence of a catalytic
amount of DBTDL (about 0.03 g). The polymer
precipitated and was then washed with distilled water. The
obtained material was dried at 100 C in vacuum.
An FTIR scan of the synthesized material showed the
following absorption peaks (cm-1): 1700 (H-bonded C=O
stretching), 1509 (N–H bending) and 3327 (N–H
stretching) of the urethane group; 3020 (C–H stretching of
benzene ring); 816 (C–H bending of 1,4-substituted benzene
ring); 1461 (C–H bending), 772 (C–C bending) of
cyclohexane ring; 2949 and 2914 (asymmetric and
symmetric C–H stretching, respectively) of CH2.
Calcd for C31H42N2O4S2: C 64.94 %, H 7.29 %, N 5.31 %;
found: C 65.23 %, H 7.41 %, N 4.91 %.
SPURs with the hard segment contents of *30, 40, 50 and
60 mass% were prepared, according to Scheme 1, by the
one-step melt polyaddition process from IPDI, diol E,
PTMO or PHCD at the NCO/OH molar ratio of 1.05.
The general procedure for the synthesis of SPURs by
this method was as follows. PTMO or PHCD and diol E or
diol E and DMPA (0.01 mol together) and IPDI
(0.0105 mol) were heated with stirring under dry nitrogen
to 95 C in an oil bath. A catalytic amount of DBTDL
(about 0.03 g) was added to the clear melt formed, and
polymerization rapidly began at vigorous stirring. The
reaction temperature was gradually raised to 130 C, and
the colourless rubber-like product formed was additionally
heated at this temperature for 2 h.
SPURs with the hard content of 50 mass% were modified
by the addition of a carboxylic group by means of DMPA.
Carboxylated SPURs were prepared in a similar way to
noncarboxylated SPURs, except that 20 and 40 % of diol E was
replaced with an ionic chain extender DMPA. These
polymers were designated as D20 and D40, respectively.
An FTIR scan of the PTMO-based SPURs showed the
following absorption peaks (cm-1): 1701–1653 (C=O
stretching); 3368–3329 (N–H stretching) and 1535–1531
(N–H bending) of the urethane group; 1112–1106 (C–O
stretching of the ether group); 1467–1447 (C–H bending of
the cyclohexane ring); 2943–2941 and 2859–2857
(asymmetric and symmetric C–H stretching of CH2, respectively);
1368–1366 symmetric C–H bending of the CH3 group.
An FTIR scan of the PHCD-based SPURs showed the
following absorption peaks (cm-1): 1745–1741
(non-bonded C=O stretching of the carbonate group); 1721–1717
(non-bonded C=O stretching of the urethane group and
H-bonded C=O stretching of the carbonate group);
1535–1528 (N–H bending) and 3368–3329 (N–H
stretching) of the urethane group; 1263–1239 and 960–959
(asymmetric and symmetric C–O stretching of the
carbonate group, respectively); 793–790 (C–O bending of the
carbonate group); 1464–1447 (C–H bending of the
cyclohexane ring); 2944–2941 and 2864–2857 (asymmetric and
symmetric C–H stretching of CH2, respectively);
1369–1365 symmetric C–H bending of the CH3 group.
Scheme 1 Synthesis of
OH + O C N R N C O + HO (CH2)2 S CH2 Ar CH2 S (CH2)2 OH
H O (CH2)4 z OH ; PHCD = H O CH2 6O C mO CH2 6 OH
; Ar =
Results and discussion
The new SPURs were colourless, high transparent solids.
All synthesized polymers were insoluble in DMSO, but
easily dissolved in THF and TChE in room temperature,
Nmethyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide
(DMAc) at room or elevated temperature, and some of the
polymers were partially soluble in DMF. Generally, the
solubility of carboxylated SPURs decreased with increase
in carboxyl groups in polymer (Table 1, Fig. 1).
In the case of other solvents, polymers dissolved
incompletely or only after being heated. SPURs with the
content of 20 mol% DMPA dissolved very well in DMF,
NMP and DMAc, while those with the DMPA content of
40 mol% swelled in these solvents. Therefore, it can be
concluded that with the increase in DMPA, the solubility of
SPURs in the said solvents decreased.
The gzred values for SPURs (contained in Table 2) ranged
from 0.70 to 6.74 dL g-1. This indicates their high molar
masses (as verified using the GPS method). Greater gzred
values were shown by polymers with a polyether soft segment
(except for 60P) than polymers derived from PHCD. Based on
the values presented in Table 2, it can be stated that the
viscosity of carboxylated SPURs increases with the increase in
the content of DMPA, whereas the more pronounced increase
was observed in the case of SPURs derived from PHCD. The
viscosity of carboxylated SPURs synthesized with the use of
PTMO is greater than the property showed by those with
PHCD. When analysing the impact of the polymer DMPA
additive, it can be stated that in most cases a 20 mol% DMPA
additive resulted in a decrease in viscosity, while a 40 mol%
DMPA additive resulted in its significant increase.
When comparing the Mn and Mw values for both soft
segments, it can be stated that, in general, greater values were
shown by the polymers derived from PTMO. A Mw=Mn
relationship indicative of molar mass dispersity for the
polymers obtained ranged from 1.12 to 2.28, and it was at a
relatively low level for polymers obtained in an alloy .
The results obtained in the course of acid-based
titration revealed a lower content of the COOH groups in all
carboxylated SPURs in relation to theoretical values. This
may be due to the fact that some carboxyl groups
contained in DMPA reacted with diisocyanate –NCO groups
The thermal stability of SPURs was obtained using a TG
analysis conducted in air atmosphere. The temperatures of
5 % (T5), 10 % (T10) and 50 % (T50) mass loss were
designated from TG curves, while temperatures of a
maximum rates of mass loss (Tmax) were determined from
DTG curves. The values of the temperatures determined
are presented in Table 3.
Temperatures of a 5 % mass loss for non-carboxylated
SPURs ranged from 305 to 325 C and from 285 to 295 C
for carboxylated SPURs. On this basis, it can be concluded
that DMPA addition resulted in the decrease in thermal
stability of the polymers obtained. In general, the polymers
derived from PTMO showed a higher T5 than the
corresponding polymers based on PHCD. This results from a
better stability of PTMO as a soft segment than that shown
When analysing the course of DTG curves, it can be
stated that the decomposition of the polymers is a two-step
process. In the case of polymers derived from PTMO, the
first step (a sharp peak with a maximum in the range of
392–405 C) may be due to the decomposition of urethane,
sulphide and ether linkages, while the second step
(temperatures in the range of 540–586 C) may be connected
with the oxidizing processes of the solid products from the
first step. In the case of polymers based on PHCD, the first
step (a wide peak in the range of 360–376 C) was due to
the decomposition of urethane, sulphide and carbonate
linkages, while the second step (temperatures in the range
Table 1 Designations of the polymers
a,b The content of 20 and 40 mol% of DMPA in the chain extender mixture, respectively
c Regular polymer derived from IPDI and diol E
4000 3600 3200 2800 2400 2000 1600 1200 800
Fig. 1 ATR–FTIR spectra of the R-PUR and selected SPURs
of 535–590 C), as for PTMO derivatives, may be
associated with the oxidizing processes of the solid products
from the first step [6, 7].
In order to better describe the process of decomposition of
the polymers obtained and to determine volatile products,
TG–FTIR analysis was conducted for R-PUR and the
following SPURs: 50P and 50C. The process was conducted
in helium atmosphere. Figure 2 depicts the DTG and TG
curves of the said polymers obtained in helium atmosphere,
while Fig. 3 presents FTIR spectra of the products of
decomposition of the polymers in their Tmax.
The FTIR spectra of gaseous products of decomposition
obtained in the course of the first step of R-PUR
decomposition (Tmax = 355 C) showed very strong double
absorption bands at 2072 and 2047 cm-1, typical of both
asymmetric and symmetric stretching vibrations C=O and a
small band at 868 cm-1 connected with stretching
vibrations C=S in carbonyl sulphide. The presence of absorption
bands at 2359 and 669 cm-1 indicated the formation of
carbon dioxide. Moreover, the FTIR spectra showed the
absorption bands typical for aromatic hydrocarbons at
3040 cm-1 (stretching vibrations C–H of a benzene ring)
and at 1508 cm-1 (stretching vibrations C=C of a benzene
ring). The presence of aliphatic compounds was confirmed
by the absorption bands at 2929–2890 cm-1 connected
with both asymmetric and symmetric stretching vibrations
of methylene and methyl groups. In addition to the
abovementioned absorption bands, there were bands typical of
alcohols on the FTIR spectra: at 3750–3550 cm-1
a Polymer insoluble in DMF
Table 3 TG and DSC data of the polymers
Table 2 gred values and GPC data of the polymers
a, b, c The temperature of 5, 10 and 50 % mass loss from the TG
d The temperature of the maximum rate of mass loss from the DTG
e I and II—first and second heating scans, respectively
(stretching vibrations –OH); at a 1050 cm-1 (stretching C–
OH), as well as bands typical of primary amines: at
3340 cm-1 (stretching vibrations N–H) and at 1666 cm-1
(bending N–H) and aldehydes: at 2820 and 2714 cm-1
(stretching vibrations C–H) and at 1730 cm-1 (stretching
vibrations C=O). Moreover, the present absorption band at
1050 cm-1 suggests that the product of decomposition was
also aliphatic ethers.
mmol –COOH in 100 g SPUR
R-PUR decomposition took place based on the
mechanisms 1 (formation of isocyanates and alcohols), 2
(formation of primary amines) and 4 generating COS .
There are three peaks visible on the DTG curve obtained
for polymer 50P: 366 and 379 C (corresponding to the
decomposition of urethane and sulphide linkages) and
393 C (corresponding to the decomposition of ether
linkage), while there is one sharp peak visible on the DTG
curve obtained for polymer 50C at 363 C (corresponding
to the decomposition of urethane, sulphide and carbonate
linkages) [6, 7]. On both curves, there are no other high
temperature peaks which would be visible in the case of an
analysis conducted in air atmosphere.
On each FTIR spectrum of gaseous decomposition
products, there were visible absorption bands at 2071 and
2049 cm-1 typical of both asymmetric and symmetric
vibrations C=O in carbonyl sulphide, absorption bands at
2376–2349 cm3 and 669 cm-1 connected with C=O
vibrations in carbon dioxide, absorption bands at
2935–2865 cm-1 typical of the vibrations of both methyl
and methylene groups as well as a band at 2274 cm-1
typical of asymmetric vibrations of –NCO group. The
presence of those bands on the spectrum results from the
decomposition of hard segments.
In the case of polymer 50P during the first stage
(366 C) only the above-presented absorption bands were
visible. This suggests that at this temperature a decay of the
hard segment took place according to the mechanisms 1, 2
and 4. At higher temperature (393 C), the intensity of a
band, which is characteristic of COS, almost disappears,
while the band’s intensity at 1111 cm-1 characteristic of
stretching vibrations C–O ether group and bands at
Fig. 2 DTG and TG curves of the R-PUR and SPURs: 50P and 50C
obtained in helium
2938–2862 cm-1 characteristic of vibrations of both
methyl and methylene groups. There are, in turn,
absorption bands at 2822 and 2710 cm-1 as well as at 1726 cm-1,
which were connected with, respectively, stretching
vibrations C–H and stretching vibrations C=O in
aldehydes. There appeared also a small peak at approx.
2170 cm-1, connected with stretching vibrations C–O in
carbon monoxide . It indicated that at that temperature
the decay of the polyether soft segment took place and its
products were aldehydes and aliphatic ethers.
In the case of polymer 50C, in addition to the absorption
bands occurring during the decay of hard segments
(according to mechanism corresponding to 50P), absorption
bands were visible at 1260 cm-1, characteristic of the
stretching vibrations C–O of carbonate group and at
1745 cm-1, characteristic of vibrations C=O of carbonate
group. The presence of absorption band at 1066 cm-1
(characteristic of the stretching vibrations C–OH) and at
approx. 3734 cm-1 (characteristic of the stretching
vibrations O–H) suggested that the product of decomposition of
that polymer was also alcohols and ethers (absorption band
at 1066 cm-1 characteristic of the stretching vibrations of
the C–O ether group). A small absorption band at
916 cm-1 indicated that during the decay of a polymer an
ethylene oxide was created.
DSC measurements were taken in the course of two heating
cycles at the temperature ranging from -100 to 200 C.
Table 3 contains numeric data determined from DSC
curves from the first and second heating cycles. Figure 4
shows the DSC curves of the selected polymers.
On the DSC curves of all polymers, only glass
transitions were visible, there are no endothermic peaks. It
indicates that the obtained polymers were amorphous ones.
The Tg values for non-carboxylated SPURs ranged from
-51 to 29 C and for carboxylated SPURs between -33
and 20 C. The analysis of DSC data from Table 3
revealed that Tg increased with the growth of the hard
segment contents in SPURs. In the case of carboxylated
SPURs, the increase in DMPA content in a polymer
resulted in a decrease of Tg. When the type of a soft
segment is a criterion for comparison, it is evident that a lower
Tg as well as a lower difference between Tg value for a pure
soft segment (PTMO-1000: -77 C, PHCD: -68 C) 
and an appropriate polymer, and at the same time better
microphase separation, was revealed by polymers derived
The data contained in Table 3 confirm that some
polymer PHCD derivatives revealed Tg at approx. room
temperature, which means that they were on the border of
plastomers and elastomers. These polymers were 50C, 60C
and PHCD-based carboxylated SPURs.
The analysis concerning the addition of DMPA to a
polymer shows that in the case of a series of polymers with
a polyether soft segment, the modified polymers had lower
Tg values. In a series of carboxylated SPURs with PHCD,
the differences are not so visible.
The mechanical properties (such as module of elasticity,
tensile strength, elongation at break) and hardness based on
A and D scales of the Shore durometer for each polymer
following their compression at a temperature in the range
of 70–140 C under a load of 10–30 MPa are listed in
Table 4, while stress–strain curves for SPURs, PHCD
derivatives, are presented in Fig. 5.
Fig. 3 FTIR spectra of volatile
products obtained at the
maximum rate of mass loss of
the thermal decomposition of
the R-PUR and SPURs: 50P and
0 50 100 150
first heating scan second heating scan
Fig. 4 DSC curves of R-PUR and selected SPURs: 50P, 50P-D40,
50C and 50C-D40
When analysing data contained in Table 3, it can be
concluded that with an increasing hard segment in
noncarboxylated SPURs their hardness increased in scale A
3900 3600 3300 3000 2700 2400 2100 1800 1500 1200 900 600
(except for polymer 60P). Hardness in scale D was
determined only for SPURs, PHCD derivatives, and the values
for those polymers increased with increasing the content of
the hard segment. In the case of carboxylated SPURs,
hardness of the polymers obtained increased with the
increase in the DMPA content (in scale A). When
comparing hardness for carboxylated SPURs with PTMO and
PHCD, it can be stated that greater values were shown by
polymers containing polycarbonate soft segment and it was
possible to mark the hardness in scale D for all those
polymers as well.
The polymers obtained showed a tensile strength in the
range of 0.42–35.2 MPa and their elongation at break
ranged between 340 and 1900 %. SPURs, PTMO
derivatives, showed very poor tensile strength. There are
considerable greater strengths in the series of SPURs with
polycarbonate soft segment, and the greatest tensile
strength value was shown by the polymer 60C (35.2 MPa),
whereas that polymer may fall into plastomers (Tg slightly
above room temperature). Both in PTMO and PHCD
series, elongations at break decreased with the increase in the
content of the hard segment (except for polymer 30P);
however, no such relationship was observed for the module
whose values ranged from 0.26 to 49.5 MPa.
Tensile strength of carboxylated SPURs increased with
the increase in the content of DMPA. The polymers derived
from PTMO showed significantly lower tensile strength
values (0.92 and 1.24 MPa) than the corresponding ones
with PHCD (12.1 and 29.4 MPa). Elongation at break of
Table 4 Mechanical properties of the SPURs
Elongation at break/%
Modulus of elasticity/MPa
a Not examined
Fig. 5 Stress–strain curves of the SPURs obtained from PHCD
carboxylated SPURs, just as their tensile strength,
increased with the increase in the content of DMPA,
whereas that increase was more pronounced in the case of
the polymers with PHCD as the soft segment. Significantly
lower values of elongation at break were shown by the
polymers synthesized with PHCD as the soft segment than
in PTMO-based ones. For carboxylated SPURs with
PTMO elastic modulus, values were in the range of 1.90 to
2.12 MPa, while for the polymers with PHCD they ranged
between 1.02 and 5.92 MPa.
The polymers obtained were colourless, transparent solids
with high molar masses. These polymers were
characterized by relatively good thermal stability. Their T5 values
were in the temperature range of 285–320 C, whereas
polymers synthesized with PTMO were more stable
thermally. The addition of DMPA to the polymers resulted in
the decrease in their thermal stability.
DSC analyses showed that all polymers obtained were
amorphous. Polymers with PTMO as the soft segment had
significantly lower Tg values (from -51 to -1 C) than the
corresponding ones with PHCD (from -10 to 29 C). A
comparison of Tg of pure soft segments and the polymers
obtained showed a much greater microphase separation
ability of the polymers derived from PTMO. The hardness
of the polymers obtained (in scale A) ranged from 19 to
81 Sh, whereas greater values corresponded to the
polymers with PHCD. The best mechanical properties among
all synthesized polymers were shown by the polymers with
PHCD as the soft segment. Their tensile strength and
elongation at break were 4.61–35.2 MPa and 340–900 %,
respectively. The polymers with PTMO had much lower
tensile strength values (0.42–1.24 MPa), but showed much
greater elongation at break values at the same time
(420–1900 %). A 40 mol% DMPA addition to the polymer
in the series of carboxylated SPURs with PHCD resulted in
a significant increase in strength.
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