72 Introduction of Phosphorus into the Polyethyleneterephthalate Molecule Downloaded via UNIV OF CALIFORNIA SANTA BARBARA on July 10, 2018 at 16:54:06 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.
G . B O R I S O V , K. TROEV, a n d
A.
GROZEVA
Central L a b o r a t o r y for Polymers, Bulgarian A c a d e m y o f Sciences, Sofia 1113, Bulgaria
The introduction of phosphorus into the polyethyleneterephtha late molecule is expected to improve not only the latter's resist ance to combustion but also to affect the transesterification and polycondensation stages as well as the side reactions taking place during its synthesis. The influence of various phosphorus-containing modifiers, i.e. diethyl phosphite (I), the sodium salt of diethyl phosphite (II) and the disodium salt of 1,2-dicarbomethoxyethylphosphonic acid (III), on the transesterification, polycondensation and side re actions were examined.
Dimethyl terephthalate was transesterified with ethylene glycol in the presence of the modifiers taken at different concentrations. The alcohol distillate (Table 1) obtained from conducting the pro cess with diethyl phosphite as modifier revealed the increased pre sence of water, acetaldehyde and acetal as compared with the alco hol distillate from the transesterification of dimethyl terephtha late with ethylene glycol (1,2). These observations were in support of the conclusion that diethyl phosphite is unsuitable as a modi fier for polyethyleneterephthalate. Table
I,
Y i e l d s o f by-products Modifier
Dy—prouuces,
J/o
Water 2-methyldioxolane Acetaldehyd Acetal
Sodium s a l t Disodium 1,2-diof d i e t h y l carbomethoxyethylphosphite phosphonate Phosphorus c o n t e n t , % 0.0 0.6 0..8 0.5 1.0 1.5 0.5 1.0 1.5 1.02 3.60 4..80 2.50 3.84 4.30 2.37 3.42 3.85
Diethylphosphite
0.13 0.15 0,,16 0.04 0.04 0.04 0.02 t r a c e s " 0.01 0.12 0..13 t r a c e s " " " 0.02 t r a c e s . II II II II II 0.08 0.11 0..15 t r a c e s 0097-6156/81/0171-0345$05.00/0 © 1981 American Chemical Society
Quin and Verkade; Phosphorus Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1981.
346
PHOSPHORUS CHEMISTRY
The s t u d i e s c a r r i e d o u t o n t h e a l c o h o l d i s t i l l a t e o b t a i n e d from the c o - t r a n s e s t e r i f i c a t i o n o f d i m e t h y l t e r e p h t h a l a t e w i t h e t h y l e n e g l y c o l i n t h e presence o f t h e sodium s a l t o f d i e t h y l p h o s p h i t e o r the di-sodium s a l t o f 1,2-dicarbomethoxyethylphosphonic a c i d i n v a r i o u s c o n c e n t r a t i o n s showed ( T a b l e I ) t h a t t h e s i d e r e a c t i o n s were m a r k e d l y s u p p r e s s e d . The h y d r o x y 1 v a l u e , m e t h o x y c a r b o n y l g r o u p c o n t e n t , a c i d v a l u e , m e l t i n g p o i n t , c o n t e n t o f d i e t h y l e n e g l y c o l and o f t h e o b t a i n e d p r e - c o n d e n s a t e s were d e t e r m i n e d i n o r d e r t o o b t a i n more d e t a i l e d i n f o r m a t i o n on t h e t r a n s e s t e r i f i c a t i o n s t a g e i n t h e p r e s e n c e o f t h e sodium s a l t o f d i e t h y l p h o s p h i t e o r d i - s o d i u m s a l t o f 1 , 2 - d i carbomethoxyethylphosphonic a c i d . The r e s u l t s o b t a i n e d ( T a b l e I I ) i n d i c a t e t h a t t h e p r e c o n d e n s a t e s m o d i f i e d w i t h sodium s a l t o f d i e t h y l p h o s p h i t e l e a d s t o a r e sin of following structure (3): VCO(CH ) )-(0-P-(CH )iOC-(
o r c
2
2
2
7 - C 0 ( C H ) - ) -0 2
2
x
0 —^ 0 ONa 0 0 With the di-sodium s a l t o f 1,2-dicarbomethoxyethylphosphonic a r e s i n o f t h e f o l l o w i n g s t r u c t u r e (4) was o b t a i n e d
acid
c
-0-(C- / / v v - - ° ( C H ) - ) (o-C-CH - CH - C-) 0 il \ — / H I» , H m 0 —' 0 0 Ρ-0 0 NaO^ 0Na The d i e t h y l e n e g l y c o l a n d c a r b o x y l g r o u p c o n t e n t s o f t h e r e s i n and i t s d i s p e r s i t y were u s e d a s a measure o f t h e d e g r e e o f s i d e reactions taking place a t the polycondensation stage. W i t h t h e sodium s a l t o f d i e t h y l p h o s p h i t e as m o d i f i e r t h e d i e t h y l e n e g l y c o l c o n t e n t i s w i t h i n 0.13 t o 2.6% a g a i n s t 1.5 t o 2.0% for the un-modified r e s i n . 2
2
2
n
v
V
T a b l e I I . A n a l y s e s o f pre-condensates m o d i f i e d w i t h sodium s a l t o f d i e t h y l phosphite or disodium 1,2-dicarbomethoxyethylphosphonate Modifier
eristics
Sodium s a l t o f Disodium 1,2-dicarbomethd i e t h y l phosphite xyethylphosphonate Phosphorus Content, %
0.0 0.5 1.0 1.5 0.4 0.7 1.2 1.5 1.9 OH value,mgKOH/g 440 436 268 310 378 403 186 398 379 CH 0,% 2.0 2.5 3.2 4.4 7.0 9.9 1.7 2.6 3.3 Acid value, mgKOH/g 0.8 2.1 3.2 2.1 3.2 3.0 3.0 2.2 3.1 DEG, % 1.4 1.1 0.2 1.2 1.5 1.2 0.8 0.3 1.4 M e l t i n g point,°C 160 146 132 167 155 155 123 165 116 The c a r b o x y l g r o u p s c o n t e n t i s i n c r e a s e d . The d i f f e r e n t i a l d i s t r i b u t i o n c u r v e ( F i g . l ) i n d i c a t e s a good p o l y d i s p e r s i t y c o m p a r a b l e w i t h t h e one e x h i b i t e d by t h e u n - m o d i f i e d o n e . 3
Quin and Verkade; Phosphorus Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1981.
72.
BORisov E T A L .
Table I I I .
Characterist
l
C
Phosphorus
in
347
Polyethyleneterephthalate
C h a r a c t e r i s t i c s o f p o l y e t h y l e n e t e r e p h t h a l a t e modi f i e d w i t h sodium s a l t o f d i e t h y l p h o s p h i t e o r d i s o dium 1,2-dicarbomethoxyethylphosphonate Modifier Sodium s a l t o f Disodium 1,2-dicarbomethoxyd i e t h y l phosphite ethylphosphonate Phosphorus c o n t e n t , %
S
0.0 0.32 0.80 1.05 1.47 0.45 0.8 1.35 1.62 η 1.33 1.23 1.42 1.18 1.28 1.34 1.33 1.32 1.28 M e l t i n g point,°C 259 259 243 252 248 259 258 258 255 COOH.IO mgeq/g 67 99 120 117 132 44 40 38 34 DEG,% 1.4 0.13 2.5 2.6 2.5 0.48 0.55 0.5 0.70 DEG-diethylene g l y c o l ; η - r e l a t i v e v i s c o s i t y ; 6
With the di-sodium s a l t o f 1,2-dicarbomethoxyethylphosphonic a c i d a s m o d i f i e r t h e d i e t h y l e n e g l y c o l c o n t e n t and t h e c a r b o x y l group c o n t e n t i s v e r y l o w (Table I I I ) . These r e s u l t s i n d i c a t e t h a t t h e u s e d m o d i f i e r h a s a l s o t h e r m o s t a b i l i z i n g p r o p e r t i e s . The i n t e g r a l and d i f f e r e n t i a l c u r v e s ( F i g . 2 ) o f m o l e c u l a r mass d i s t r i b u t i o n show t h a t t h e p o l y d i s p e r s i t y o f m o d i f i e d r e s i n i s com parable t o that o f the un-modified. The t h e r m o g r a v i r a e t r i c c u r v e s o b t a i n e d i n d i c a t e t h a t t h e m o d i f i ed a n d u n - m o d i f i e d r e s i n s b e g i n t o decompose a t 300°C. The c o m b u s t i o n t e s t s o f r e s i n m o d i f i e d w i t h t h e s o d i u m s a l t o f d i e t h y l p h o s p h i t e samples i n d i c a t e ( T a b l e IV) t h a t w i t h t h e i n c r e a s e i n t h e p h o s p h o r u s c o n t e n t t h e s a m p l e s c e a s e t o b u r n and t h e o v e r a l l time o f combustion l e n g t h e n s . Table I V . Data from Combustion T e s t s W e i g h t Oxygen Time r e q u i r e d Duration of Modifier Index of f o r complete combustion combustion,sec. residue, P, % after igni % tion,sec . Without 5.2 modifier 19 181 181 0. 0 Diethyl phosphite sodium
0. 32 0. 80 1. 05 1. 47 0. 45
Disodium 1,2-dicarbornethoxy- 0. 80 e t h y l p h o s - 1. 35 1. 62 phonate
extinguished 11 11 II
II
11 11 II
188 220 265 275 202
8.0 21.0 30.0 29.9 25.0
19.8 21.6 21.8 22.4 21.4
229 227 240
50.0 52.0 50.0
22.8 23.6 24.0
The r e s i d u e a f t e r c o m b u s t i o n i n c r e a s e s c o n s i d e r a b l y f r o m 5.2% f o r t h e u n - m o d i f i e d r e s i n t o 3 0 % f o r t h e one c o n t a i n i n g 1.05% of phosphorus. The o x y g e n i n d e x c h a n g e s f r o m 19 f o r t h e u n - m o d i f i e d r e s i n t o 22.4 f o r .the one c o n t a i n i n g 1.47% o f p h o s p h o r u s .
American L.iemicst Society library 1155 isth St. H. w.
Quin and Verkade; Phosphorus Chemistry Washington, D. C. Society: 20036Washington, DC, 1981. ACS Symposium Series; American Chemical
348
PHOSPHORUS CHEMISTRY
Figure 1. Molecular mass distribution curves from phosphorus-containing poly ethyleneterephthalate sample with 0.74% phosphorus modified with sodium salt of diethyl phosphite. Key; 1, integral curve; 2, differential curve; and 5, integral curve of phosphorus distribution.
0
10 20 30 40
50 ,-3 M .10 v
w
7A
1
2.2 100
zo
90
1.8
80
1.6
70
Figure 2. Molecular mass distribution curves from phosphorus-containing poly ethyleneterephthalate sample with Ο.8ΟΦ0 phosphorus modified with disodium salt of 1,2-dicarbomethoxyethylphosphonic acid. Key; 1, integral curve; and 2, differ ential curve.
60
1,2
50
1.0
i.0
0,8
30
0.6
20
OA
10
0.2
0
18
26
34 M . 10" v
Quin and Verkade; Phosphorus Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1981.
72.
BORisov E T A L .
Phosphorus
in Polyethyleneîerephthalate
349
The s a m p l e s m o d i f i e d w i t h t h e d i - s o d i u m s a l t o f 1 , 2 - d i c a r b o m e t h o x y e t h y l p h o s p h o n i c a c i d showed ( T a b l e I V ) t h e w e i g h t o f r e s i d u e r e a c h i n g 52%. LITERATURE CITED
1. Troev, K.; Grozeva, At.; Journal 1979, 15, 437. 2. Troev, K.; Grozeva, At.; Journal 1981, 17, 27. 3. Troev, K.; Grozeva, At.; Journal 1979, 15, 1143. 4. Troev, K.; Grozeva, At.; Journal 1981, 17, 31. RECEIVED
July 7,
Borisov, G. European Polymer Borisov, G. European Polymer Borisov, G. European Polymer Borisov, G. European Polymer
1981.
Quin and Verkade; Phosphorus Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1981.
