CC BY
129
UDC 668.395
SYNTHESIS AND STUDY OF SOME PROPERTIES OF HARDENED STYRENE
CONTAINING COPOLYMERS
H.A.Mamedaliyev, N.A.Zeynalov*, E.S. Mammadova
"Olefins Scientific Research and Production Centre' OJS, Baku [email protected] *M.Nagiev Institute of Catalysis and Inorganic Chemistry, NAS of Azerbaijan
Received 24.05.2017
Importance of the present work consists in study and application of novel products of synthesis of polyurethanes based on copolymers of monoacrylate oligooxypropyleneglycols and styrene. There have been studied physico-mechanical and adhesion properties of the synthesized polyurethanes. It has been established that the obtained polyurethanes are thermally stable corrosion-resistant. They are used as glues and coatings of cold hardening.
Keywords: polyesters, copolymers, hardening, styrene, oligomerization, IR-spectra, glues, coatings.
At present, glues and coatings are implemented in many branches of industry but compositions of cold hardening are of the greatest interest in this regard as in this case necessity of thermal treatment of wares is excluded [1-5]. Therefore, the problem of synthesis of novel non-toxic glues and coatings of cold hardening that have high adhesion properties is actual.
The present article is dedicated to synthesis and study of some properties of the hardened styrene-containing copolymers of monoacrylate oligooxypropyleneglycols (AOP) with styrene.
Synthesis consists of two stages:
1) obtaining of AOP;
2) copolymerization of AOP and styrene.
Obtaining of AOP by cationic polymerization of propylene oxide (PO) under the action of antimony pentachloride in the presence of methacrylic or acrylic acid (AA) as a cocatalyst has been described in [2, 3] (first stage).
Conditions and results of the experiments conducted by us using SnCl4 have been presented in Table 1.
The synthesized oligomers have the general formula:
CH^C-COOi-CH^CH-OiT-H ,
I
R
I
CH3
a coefficient of
where R=H, CH3 and n is polymerization.
The experimental data set in Table 1 show that by varying PO:AA ratio it is possible
to obtain oligomers of different MM in the range from 600 to ~5000.
Table 1. Conditions* of synthesis and some characteristics of the oligomers
Molar ratio PO:AA Concentration of SnCl4, mol/l Bromine number, q Br per 1GG g Molecular mass, MM ** i с" n20 nn d420
9:1 G.G476 24.G 6GG 10 1.4480 1.0024
9:1 G.127G 25.9 62G 9 1.4480 1.0024
9:1 G.222G 24.2 6GG 10 1.4480 1.0024
25:1 G.G62G 8.G 1600 26 1.4515 1.0024
25:1 G.155G 11.4 14GG 23 1.4515 1.0024
25:1 G.217G 11.G 1500 24 1.4515 1.0024
5G:1 G.G466 б.1 2500 43 1.4531 1.0200
5G:1 G.155G б.9 2300 38 1.4531 1.0200
5G:1 G.216G б.2 2550 43 1.4531 1.0200
85:1 G.G462 3.2 4900 83 1.4550 1.0015
85:1 G.154G 3.5 4550 77 1.4550 1.0015
85:1 G.216G 3.3 4800 81 1.4550 1.0015
of the reaction - 24 hours;
** MM is determined according to bromine numbers.
In Table 1 it may also be seen that the catalyst concentration in the studied interval from 0.0472 to 0.2160 mol/l practically has no influence on molecular mass MM of the oligomers.
IR spectra confirm the structure of the obtained oligomers. In these spectra there are absorption bands characteristic for valence (2900-2850 cm-1) and deformational (14501440 cm 1) vibrations of - CH bond in -CH3-
and -CH2-groups as well as absorption bands belonging to valence vibrations of simple ether (1100-1200 cm-1), double (1640 cm-1) and
complicated ether
—c=O
I
. O- .
(1720 cm 1) bonds.
Relative intensity of the last two bands of absorption decreases with an increase of the oligomer MM, i.e. with lowering of acrylic group concentration. Absorption band at ~3500 cm-1 corresponds to hydroxyl group in the oligomer macromolecule.
The obtained oligomers AOP are oil-like viscous or highly-viscous products of light-yellow color which are well-soluble in organic solvents. AOP polymerizes thermally or in the presence of such initiators of radical polymerization as benzoyl peroxide (BP), azo-bis-isobutyronitrile and others.
Experimental part
Copolymerization of AOP and styrene is carried out in the presence of BP or tert-butyl-perbenzoate (1-3 wt %) by stepwise rise of temperature respectively from 70 up to 1300C and from 100 up 1600C with keeping half an hour after each 10 degrees.
Depending on the ratio of components (AOP:styrene) the synthesized copolymer is the product changing its state from sticky glue mass to wax-like matter and having the following structure:
R
CH
■ CH2-C-CO^ CH2CH-aj-r H CH2— CH----
C6H5
where R= H, CH3; n= 9-85 and m=5-20.
Some physico-mechanical properties of the copolymers are presented in Table 2.
The hardening process has been studied for the copolymers containing fragments of AOP of various MM (n=10 and MM=600, n=25 and MM=1500, n=57 and MM=3200), these
copolymers being synthesized at different ratios AOP:styrene (100:70 and 100:50, Table 2).
Table 2. Some properties of copolymers based on AOP and styrene (initiator is tert-butylperbenzoate - 1-3 wt%)
MM of AOP Ratio of components AOP:styrene Viscosity by spherical viscosimeter, cSt Conditional MM of copolymer DTA data Characteristics
temperature of destruction starting, 0C loss of mass, %
600 100:70 2100 12.3104 200 13.4 Highly-viscous, sticky, elastic mass
1500 1600 2.8-104 200 8.5 Highly-viscous, sticky, elastic mass
2500 2000 6.1104 190 13.5 Highly-viscous, sticky, elastic mass
3200 1500 1.2104 175 15.3 Viscous, elastic mass
1500 100:50 650 3.8104 160 13.5 Sticky, oil-like mass
As a hardener polyisocyanate (PIC) of trade mark B corresponding to specifications TU 113-03-29-6-84 (content of NCO-groups -29.1%) and n', n" , n"'-triphenylmethane tri-isocyanate (TPhMTI) are used, the latter being taken as 20 wt % solution.
When obtaining polyurethane coatings, proceeding of a number of chemical reactions is possible [6-8].
In the system under study two competing reactions occur:
-OH + -OCN
-NH2 + -OCN •
-O-CO-NH- , urethane
► ~NH-CO-NH-urea (carbamide)
The reaction of carbamide fragment formation taken place with significantly larger rate than the one leading to urethane group.
A basis reaction is urethane formation which proceeds according to mechanism of migrational polymerization based on the capability of addition of labile hydrogen atoms of polyester to nitrogen atom of -NCO-group.
The course of hardening and the structure of the final products may be described as following:
m
Rn-OH + R' -N=C=O where
Rn =
R
I
О
Rn-O-C-NH-R' ,
ÇH,
CH2-C-CO^+" CH2CH-O|^-H
n=9-25, m=5-50 and R' - is the residue of the isocyanate hardener.
In addition, upon hardening of the film in the air the reaction of isocyanate groups with water vapour occurs that brings about formation of urea fragments:
RNCO + H2O -► R-NH-C-NH-R' .
-CH2 II
O
Use of an excess of isocyanate groups stipulates a possibility of the reactions where allo-isocyanate and biurethane fragments are formed, especially if hardening is performed at elevated temperatures. With this, the more is an excess of isociyanate groups, the more is probability of urethane, alloisocyanate and biurethane bonds.
Results and their discussions
One of the most spread methods for estimating an extent of conversion is a determination of the yield of insoluble products (gel fraction) in the course of the process of reticular polymer formation. The content of gel fraction is found by subjection of polymers sample to extraction with acetone in Soxhlet apparatus. The extents of hardening determined for the polyurethane samples obtained at various ratios of the initial components are given in Table 3.
Table 3. Extents of hardening polyurethanes obtained at various ratios of polyester and hardener
Ratio polyester and PIC 100:20 100:4.8 100:9.6 100:14
Extent of hardening, % 96.5 95.7 95.3 95.4
Ratio polyester and TPhMTI 100:5 100:15 100:20 100:25
Extent of hardening, % 90.7 92.3 95.2 91.3
In Figure 1 kinetics of three-dimensional isocyanate polyaddition in the system containing copolymer of AOP with styrene (1:0.7) and TPhMTI is illustrated.
3.0
g 2.0
£
О о £
1.0
200
150
X1
о4
100 8
1) о
50
50 100 150 mm Fig. 1. Kinetics of urethane-formation reaction. Change of viscosity of 50% solution in toluene and conversion of isocyanate groups in dependence of NCO/OH-groups ratio: 1,1 - 1.7, 2, 2 '- 2.5, 3,3 - 3.4.
In this figure it is seen that the reaction rate rises with an increase of NCO:OH ratio. A sharp rise of the system viscosity is also observed, the viscosity augmenting much more rapidly at larger ratios of NCO and OH groups.
The results of the studies evidence that an intensive rise of the system viscosity occurs at the expense of strong intermolecular interactions. Rising of the system viscosity in the field of conversion adjoining the gelation point is accompanied with an abrupt increase of MM and widening of MM distribution curve. This is related with sharply non-uniform propagation of chains near the gelation points, the chains propagation occurring with preservation of the particles form similarity that is close to the spherical one. Therefore, the polymer network formed starting from the gelation points is characterized by a large irregularity of distances between nodes.
Experimental researches of the process of formation of polyurethane coatings based on the copolymer of AOP and styrene showed that the process of formation of spatially-cross-linked polymer, in addition to occurrence of chemical reactions, is accompanied by complex structural conversions and is determined by a whole number of such factors as reactivity of the initial components, elasticity and tendency to formation of physical bonds.
In Figure 2-4 kinetics of the above-mentioned copolymer hardening with PIC at room temperature is described. As is seen in the figures,
n. c
CH2—CH
m
the reactivity of the polyester rises with an increase of the ratio of NCO- and OH-groups. An abrupt accretion of the solution viscosity is also watched. It is remarkable that at larger ratios of the reacting groups the viscosity rises faster. The process of gel-formation starts in approximately 20-25 min, whereas the system hardens in 100150 min after the beginning of the reaction.
3.0
cN
2.0
o o
25
1.0
1' 2' ■
/3'
10
1) o
50
100
150
200
Fig. 2. Change of concentration of NCO/OH-groups and viscosity from the time in dependence of ratio NCO/OH: 1 - 3.4, 2 - 2.5, 3 - 1.7; AOP:styrene= 100:70. MMAOP=1500.
3.0
cN
2.0
o o
25
1.0
1 2 3 1 2 3
1 2 3
10
X1
&
T3 O
50 100 150 200
x, min
Fig. 3. Change of concentration NCO/OH-groups and viscosity from the time in dependence of ratio NCO/OH: 1 - 3.4, 2 - 2.5, 3 - 1.7; AOP:styrene = 100:70. MMAOP=600.
As is evident, the interaction proceeds with the same rate up to extent of NCO- and OH-groups conversion - 0.55. Then, during formation of the reticular polymer some retardation of the process is observed as a result of which appearance of gel is fixed only in 2.0-2.5 hours. A decrease of the process rate is probably related to an increase of the system viscosity in the course of urethane-formation reaction and an augmentation of MM which causes lowering of
the chain fragments mobility and hinders a contact between oligomers groups.
3.0 -
cN
2.0
o u
^ 1.0
1 2 3 1 2 3
1 2 3
J_
_L
10
cN
o
8 .2
O
50 100 150 200 t. min
Fig. 4. Change of concentration NCO/OH-groups and viscosity from the time in dependence of ratio NCO/OH groups: 1 - 3.4, 2 - 2.5, 3 - 1.7. AOP:styrene= 100:50, MMaop=1500.
An analogous situation is observed when the system viscosity is investigated in dependence on time (Figure 5).
30
20
> 10
3 2 1
3 2 1
50
200
100 150 t, min
Fig. 5. Change of concentration dynamic viscosity of the system at various ratio of NCO/OH-groups: curves 1, 1', 1" - MMAOP= 500; curves 2, 2 , 2'' - MMAOP=1500; curves 3, 3, 3" - MMAOP=3200; at the ratio NCO/OH=1.7, 2.5 and 3.4 respectively.
It has been established that the optimal time of hardening is ~(2.0-2.5) hours depending on the hardener concentration. The highest rate of hardening is registered at PIC concentration 20-30% of the copolymer weight (Figure 6). Further increase of the hardener concentration slightly influences the rate of the functional groups interaction.
6
8
6
t. min
8
6
20
60
40 e, %
Fig. 6. Dependence of stress from deformation of polyurethanes based on AOP and styrene (100:70) at the ratio of NCO/OH-groups: 1 - 3.4, 2 - 2.5, 3 - 1.7.
Formation of urethane groups upon interaction of the copolymer with PIC is also confirmed by the data of IR spectroscopy. The fragments of the IR spectra are shown in Figure 7 from which it becomes evident that the band characteristic for urethane group (1730 cm-1) is really present.
й
о &
о
гл <
1730
1420
920
A
Л 1 A
1730
K" iX" I
л 1730 11420 т 920
b
1660 - 920
1420
Л Ai Л' A
I22S0 |
I , 1660 il420 |!
I Ал
5 920
22S0
1730 \\l710
й i^o
/{ A
18 16 14 10 8 24 22 18 14 10 8
Fig.7. Fragments of IR spectra of hardened polyurethane samples: 1 - initial polymer; 2 - polyiso-cyanate of trade mark "B"; 3 - copolymer hardened after 5 hours; 4 - hardened copolymer after 24 hours; 5 - hardened copolymer after 48 hours.
In the course of the process the band with maximum at 1730 cm-1 becomes intensely enlarged, that band belonging to vibrations in iso-cyanurate cycle.
At the final stage of the polymer formation an actual rearrangement of the absorption band of valance vibrations of the polymer carbonyl groups takes place, i.e. the band at 1710 cm-1 becomes more intensive and the band at 1710 cm-1 is recorded in the form of "an arm" that testifies to preferential proceeding of trimerization reaction in the system. This is confirmed by an increase of intensived the band near 1420 cm-1 pertaining to valance vibrations of isocyanurate cycle.
Analysis of the IR spectra of the hardened polymers also shows that in the process of interaction, in parallel to a rise in intensity of the band at 1710 cm-1, a band at 1660 cm-1 appears that is intrinsic to vibrations of carbonyl group in urea fragments.
Thus, the results of spectral researches in combination with kinetic studies of the viscosity properties allow us to establish that the urethane-formation process proceeds through interaction with hydroxyl groups in the copolymer of AOP and styrene, these groups being preliminary by weakened by hydrogen bonds. The rate of the reaction of urethane formation is determined by conditions causing hydrogen bonds weakening in the initial copolymer.
The data of the IR spectra of the hardened polymers point to a significant increase in an amount of urethane fragments.
Below some properties of the synthesized polyurethanes are considered.
For obtaining films the copolymers are preliminarily dissolved in xylene (1:1) and then are mixed with the hardener (~20-25 mass parts per 100 mass parts of the polyester). The formed solution is applied on the tested surface (fluoroplast or glass) and is kept 24 hours at room temperature or at the temperature 900C during 90 min for complete hardening. The experimental data on some physico-mechanical properties of the hardened copolymers are presented in Tables 4 and 5.
As is seen in the Tables, irrespective of the nature of hardener the polyurethane films have satisfactory physico-mechanical properties.
The coatings are transparent glossy films which are easily removed off the surface of fluoroplast. Thickness of the film is measured and its physico-mechanical indices are determined.
a
4
4
3
2
Table 4. Some physico-mechanical properties of the polyurethane coatings based on the copolymer of AOP and styrene
Composition of polyurethane Elasticity according to "ShG-1" scale, mm Relative Impact strength, kgs/m
Oligomer, n Ratio of oligomer and styrene Hardener*, % hardness, conditional units
TPhMTI**
A0n-10 1:0.7 30.0 1 0.75 5.0
AOn-25 rt rt 30.0 1 0.62 5.0
AOn-57 rt ri 30.0 1 0.50 5.0
PIC-B
A0n-10 1:0.7 30.0 1 0.60 5.0
AOn-25 it rt 30.0 1 0.50 5.0
AOn-57 rt rt 30.0 1 0.50 5.0
Composition of coating Tensile strength, 5, kg/sm2 Impact strength, kgs/sm Elasticity, mm Pull strength (steel), MPa Heat resistance by Vicat, 0C
ratio AOP:styrene hardener, wt. part solvent, wt. part from outside from inside
49:49 35 Xylene 100 170-185 >50 <50 3 6.2-6.5 250
55:38 5 Xylene 100 40-50 >50 <50 3 2.70-2.75 250
58:21 40 Xylene 100 250-270 >50 <50 >1 6.25-6.30 250
58:21* 20 Xylene 50 70-80 >50 <50 >1 4.25-4.45 250
49:49 50 Toluene 50 100-120 >50 <50 >1 4.00-4.50 250
55:38* 20 Xylene 50 Acetone 50 190-200 >50 <50 >1 4.00-4.50 250
**PIC of the trade mark "B"
*Plasticizer - dioctylphthalate,15 mass part **TPhMTI (20% solution)
Table 5. Some physico-mechanical indices of the coatings
It should be noted that the films obtained on the basis of copolymers of the ratio AOP: styrene=100:70 exhibit higher physico-mechani-cal properties in comparison with the films based on copolymers of the ratio AOP:styrene = 100:50. This is apparently related to the circumstance that in the latter case in the copolymer chain fraction of lateral chains is larger. Therefore, there is a large probability that not all of them will take part in formation of crosslinks. A part of hydroxyl groups in the lateral chains of the copolymer is spent on interaction with moisture of air generating urea fragments. This brings about an increase of the network imperfection. Besides, an increase of urea fragments will lead to enhanced rigidity. As a whole, physico-mechanical indices of the films in this case will be worsened.
The data offered in Table 6 show, that an increase in network of polyurethane coatings causes an augmentation of hardness and strength of the coatings simultaneously lowering their elasticity and relative elongation. As an analog, the tape coating LETSAR-LPT (specification TU-30368-76) is considered which consists of
the applied layer of silicon-organic rubber of radiation vulcanization. The comparative characteristics are presented in Table 7.
The results of the tests show that the compositions have an increased strength upon gluing rubber to metal, the time of setting being 5-8 min. The samples possess an increased thermal resistance.
Thus, there have been obtained polyure-thanes of cold hardening which were tested as corrosion-proof coatings for gas- and crude oil pipelines. Optimization of composition of mixes for polyurethane coatings has been carried out. It has been established that the optimal composition contains AOP of molecular mass ~1500-2000 at the ratio AOP:styrene =100:70, PIC being used as a hardener in the amount 40 wt %. The unhar-dened copolymers have been tested as mastic and hermetics, adhesion properties and thermal resistance of which are significantly higher than those of the known analogs. The hardened co-polymers have been tested as glues having strong adhesion properties especially when glueing steel [9, 10].
Table 6. Some physico-mechanical indices of polyurethane coatings on the basis of the copolymer of AOP and styrene
Composition of polyurethane
oligomer
hardener
Elasticity according to "ShG-1" scale
mm
Relative hardness, conditional units
Impact strength, kgs/m
А0Р-10*
АОР-25
АОР-57
АОР-10
АОР-25
АОР-57
TPhMTI
11_11
11_11
Р1С
0.75 0.62 0.50 0.60 0.50 0.45
5.0 5.0 5.0 5.0 5.0 5.0
А0Р-10** АОР-25
Р1С
0.6 0.6
5.0 5.0
*AOP:styrene=100:70, content of hardener - 30% mass
**AOP:styrene=100:50
Table 7. Comparative characteristics of some physico-mechanical indices of the synthesized composition and analog
№ Indices Synthesized composition Analog (LETSAR-LPT)
1 Breaking strength, MPa 25.0-30.0 10-25
2 Pull adhesion (steel), MPa 2.5-3.0 1.5-2.0
3 Elasticity according to "ShG-1" scale, mm 1 10
4 Thermal resistance, °C 180-200 80-85
5 Shear strength (steel), MPa 10-12 5-10
n и
il it
и и
References
1. Mamedova E.S., Tagiev R.B., Dzhavadova Zh.A., Babaev M.I. Poluchenie i primenenie polime-rizatcionnosopobnykh oligomerov propilenoksida i epikhloridina // Sb. nauchn. tr. VNIIOlefin "Mono-mery i poluprodukty na osnove nizshikh olefinov". Moskva. 1989. S. 48-58.
2. Mamedova E.S., Babaev M.I., Gasanova I.V., Leeogonkii B.I., Zeinalov N.A. Cleevaia kom-pozitciia. A.s. 1799892 SSSR. B.I. 1993. № 9.
3. Mamedova E.S., Tagiev R.B., Muslim-zade Z.M., Dzhavadova Zh.A. Kationnaia oligomerizatciia epikhlorgidrina v prisutstvii akrilovoi kisloty // Plastmassy. 1989. № 9. S. 30-32.
4. Mamedova E.S., Babaev M.I., Tagiev R.B., Zeinalov N.A. Issledovanie sinteza oligooksipropilen-glikolmaleinatov // Plastmassy. 1990. № 11. S. 8-10.
5. Samedova E.M., Svetikov Iu.Iu., Aliguliev R.M., Mamedova E.S., Aslanov Ch.S. Cleevaia kom-pozitciia. A.s. №1636439 SSSR. B.I. 1991. № 11.
6. Mamedaliev G.A., Mamedova E.S. Poluchenie poliuretanov na osnove gidroksiakrilatnykh poliefirov // Voprosy himii i him. tekhnologii. 2009. № 6. S. 38-43.
7. Mamedova E.S., Baladzhanova G.M., Ismailova Sh.I. Poluchenie i primenenie lineinykh i tciclicheskikh oligomerov kationnoi polimeri-zatciei geterotciclov // Himiia i neftehimiia. 1999. № 1. S. 15-25.
8. Mamedova E.S., Nasirova A.B., Tagiev R.B. Kompozitciia dlia pokrytii holodnogo otverzh-deniia. A.s. №1666501. SSSR. B.I. № 28. 4 s.
9. Mamedova E.S., Mamedaliev G.A. Uspehi v ob-lasti sinteza oligomerov i ikh primenenie v kachestve promyshlennogo syria. Baku: Elm, 2011. 224 s.
10. Mamedaliev G.A., Mamedova E.S. Polimeriza-tcionno-sposobnye oligomery i ikh sopolimery -osnova sinteticheskikh masel i poliuretanovykh materialov. Baku: Elm, 2013. 167 s.
borkímí§ stírol torkíblí sopolímerlorín síntezí уэ todqíqí
Q.A.Mamm3d3liyev, N.A.Zeynalov, E.S.Mammadova
Verilan i§in ahamiyyati monoakrilatooksipropilenqlikolun stirolla sopolimeri asasinda poliuretanlann yeni sintez mahsullarinin tadqiqi va istifadasidir. Sintez olunmu§ poliuretanlann fiziki-mexaniki va adgeziya xassalari óyrsnilmiíjdir. Müayyan olunmu§dur ki, sintez olunan PU termo va korroziyaya davamlidirlar. Onlar yapi§qan va soyuq barkima ortüklari kimi istifada olunur.
Agar sozlar: poliefirlar, sopolimerlar, barkima, stirol, oliqomerla^ma, ÍQ spektr, yapi§qan, ortük.
СИНТЕЗ И ИССЛЕДОВАНИЕ СВОЙСТВ ОТВЕРЖДЕНЫХ СТИРОЛСОДЕРЖАЩИХ
СОПОЛИМЕРОВ
Г.А.Мамедалиев, Н.А.Зейналов, Э.С.Мамедова
Важность настоящей работы состоит в исследовании и применении новых продуктов синтеза полиуретанов на основе сополимеров моноакрилатоолигооксипропиленгликолей со стиролом. Изучены физико-механические и адгезионные свойства синтезированных полиуретанов. Установлено, что последние термостойки и корро-зионностойки. Они используются в качестве клеев и покрытий холодного отверждения.
Ключевые слова: полиэфиры, сополимеры, отверждение, стирол, олигомеризация, ИК-спектры, клеи, покрытия.
