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Molecular properties and phase conditions of polymers with mesogenic groups in the main chain
Polymers with mesogenic groups in the main chain
1253
REFERENCES 1. P. J. FLORY, Principles of Polymer Chemistry, p. 12, 68, Cornell University Press, Ithaca, New York, 1953 2. V. V. KORSHAK and S. V. VINOGRADOVA, Ravnovesnaya polikondensatsiya (Equilibrium Polycondensation). p. 38, 132, Nauka, Moscow, 1968 3. B. A. ZAITSEV and R. F. gI~ELEVA, Vysokomol. soyed. A23: 1783, 1981 (Translated in Polymer Sci. U.S.S.R. 23: 8, 1957, 1981) 4. B. A. ZAITSEV, G. I. ]{HRAMOVA and L. L. DANTSIG, Vysokomol. soyed. A24: 2467, 1982 (Translated in Polymer SoL U.S.S.R. 24: 12, 2831, 1982) 5. M. J. RHOAD and P. J. FLORY, J. Amer. Chem. Soc. 75: 5, 2216, 1950 6. B. A. ZAITSEV, L. L. DANTSIG, O. I. KHRAMOVA and G. A. SHTRAIKHMAN, Zh. prikl, khimii 50: 2, 411, 1977 7. A. M. TOROPTSEVA, K. V. BELGORODSKAYA and V. M. BONDARENKO, Laboratornyi praktikum pc khimii i tekhnologii vysokomolekulyarnykh soyedinenii, p. 125, Khimiya, Leningrad, 1972 8. L. B. SOKOLOV, Polikondensatsionnyi metod sinteza polimerov (Polycondensatioa Method of Polymer Synthesis), p. 35, 65, Khimiya, 1966
Polymer Science U.S.S.R. ~ol. 25, No. 5, lap. 1253-1259,1983 Printed in Poland
0032-3950]83 $10.00+.0@ C) 1984 Perga~non Press Ltd.
MOLECULAR PROPERTIES AND PHASE CONDITIONS OF POLYMERS WITH MESOGENIC GROUPS IN THE MAIN CHAIN* A. I. GRIGOR'YEV, N. A. ANDREYEVA,A. YU. BILIBIN, S. S. SKOROK~ODOVand V. Y~.. E s x ~ Institute of High-Molecular Weight Compounds, U.S.S.R. Academy of Sciences
(Received 9 February 1982) A study was made of molecular properties and phase conditions of polydecamethylene terephthaloyl di-p-oxybenzoate containing mesogenic groups in the main chain. It was shown that this polymer in melt changes into the liquid-crystalline state with the formation of a defective laminated structure.
WE studied previously [1] morphological properties of a polymer containing mesogenie groups in the main chain, separated by flexible polymethylene bypasses--poly-p-phenylenesebaeyl-di-p-oxybenzoate (PPSB) synthesized from hydroquinone. It was established that liquid-crystalline order is established in the melt of this polymer. * Vysokomol. soyed. A25: 1~o. 5, 1082-1085, 1983.
A . I . G m o o ~ ' ~ v t~ a/.
1254
I n this s t u d y we c o n t i n u e d t o e x a m l n e p o l y m e r s with mesogenie groups in t h e m a i n chain using p o l y d e c a m e t h y l e n e terephthaloyldi~o-oxybenzoate ( P D M T B )
--,CH, I,
2/10
it ~ 0
II ~ 0
--~'/"
11
0
c--o--1,
It 0
| ~n
p r e p a r e d from t e r e p h t h a l i c acid. Polymers with different intrinsic viscosity values were synthesized by polycondensation of 4,4-bis-(chlorocarbonylphenylene)terephthalate with decamethylene glycol in diphenyloxide at 473°K. Polymers with a viscosity of less than 0.2 m3/kg were prepared with non-equimolecular ratios of dichloranhydride and glycol. Synthesis of polymers will be described in detail in subsequent publications. Investigations were carried out in solution, in the solid state and in melts at different temperatures by light scattering, X-ray and viscometry. Intrinsic viscosity values of solutions in trifluoroacetic acid (TFAA) were measured using an Ubbelohde viscometer at 298°K, molecular weights Mw and second virial coefficients A2 by light scattering using a photoelectric nephelometer (PPS-2). The refractive index increment was determined from the formula
tin~do= ~ (n-- no), where v is the partial specific volume of the polymer, n and n0--refractive indices of the polymer and solvent (n was determined by immersion). Molecular parameters of PDMTB determined in TFAA solutions are given in Table 1. From the curve showing the dependence of log [~] on log Mw (Fig. 1) coefficients K~ and a were determined in the Mark-Kuhn-Houwink equation [~]----K~.M =. Kv=8"5
X 10 -s
a=0.65
0.4 0.2 0 -0.2 -0.4 I
q.2
I
I
q.6
I
I
I
I
5.4/o#M
FIe. 1. Dependence of log [~] on log Mw for PDMTB samples in TFAA. E x t r a p o l a t i n g t h e c u r v e showing the d e p e n d e n c e of [~]/M*----f(M~) t o M = 0 , a c c o r d i n g to t h e S t o c k m a y e r - F i x m a n e q u a t i o n [2], we d e t e r m i n e d t h e value o f Ko=F(~/M) t, where h0~ is t h e average square o f u n p e r t u r b e d dimensions o f spheres, F - - F l o r y c o n s t a n t equal ~o 2.1 × 10=Smole -1 (Fig. 2). H e n c e r e l a t i v e u n p e r t u r b e d dimensions (h~/M)*----1.2× 10 -1° m, which in order o f m a g n i t u d e ~orresponds t o u n p e r t u r b e d dimensions o f o r d i n a r y flexible-chain p o l y m e r s .
Polymers with mesogenic groups in the main chain TABLE I. MOLEOULA~ P A ~ Z T E R S , TRANSITION INTO
PDMTB samples
[t/],m'/kg
~eT.Tn~o POINTS AND TEMPERATURES OF
ISOTROPIC STATE OF
TJU..~
.M~ X 1 0 - ~
PDMTB s~PLES
A, X I0',
Ti, K
~[Tmelt, g
m'.mole/kgi
6.0 2"8 1"8 2.8
0.15 0.5 1.2 1.4
0.04 0-11 0"16 0.20
1255
523 543 543
478 503 503
Conformation statistics were used for polymers of similar chemical structure t o calculate the length of Kuhn segment A----28X 10-z° m [3]. Using the length o f the recurrent unit of the chain 32.2 x 10 -1° m, obtained from X-ray results the statistical segment of the chain may be calculated for PDMTB macromoleeules in TFAA, where L is the entire chain length. I t appears t h a t _4----24 × 10 -z° m. Therefore, theoretical calculation [3] agrees with experimental results.
A=-h]/L
T_~l'l~m 15-
:rq
11,41/z~10a 6 L
12-
5
9
q
6
,3
3 1
1
I
1
2
3 t,ll/Z,lO -ttz
FIG. 2
I
I
503
~23
]
5q3 T,K
FIG. 3
FIG. 2. Dependence of [~]/M* on M + for PDMTB samples in TFAA. FZG. 3. Dependence of the intensity of light passing through crossed Nicols on temperature for sample 2 (PDMTB) (rate of heating the sample being 1 deg/min). Melting points and temperatures of %Tansition of polymers into the isotropic state were determined using an M-21 mirror galvanometer according to the in, tensity of light passing through crossed Nicols in a device of the type previously described [4]. Samples were melted between two cover glasses placed inside the terminal of an electric oven. Figure 3 shows the course of intensity curve of light passing through crossed Nieols, according to temperature for sample 3 of PDMTB.
1256
A.I.
T~sL~ 2. ~
A
~
GBmo~Y~.v e~ a/.
DISTANCESd FOB SA~rp~ 3 (PDMTB) AT DIFFERENT TF~JPEBAk't~ES
T, K
293 (before melting) 528
d × 101° m 47.8 4.44 30.3
25-8 4.10 9.1 (halo)
47.4 4.76
27-2 4.53
548 293 (after melting)
13"0 3"48 4"9 (halo) 5.0 (halo) 13.6 4.26
© |
FIO° 4a, b
8.80 3.48
6"38 3"18
5"61 3"02
4.76
9"43 3.96
7"98 3"71
5"55 3"43
5.18 3.14
Polymers with mesogenio groups in the main chain
1257
Table 1 shows melting points and temperatures of transition into the isotropic state of the samples examined. I t can be seen that with an increase in polymer MW, melting points and temperatures of transition into the iso~ropie state somewhat increase and reach a maximum value. For the samples examined the temperature range of existence of the mesomorphous phase is independent of MW. X-ray investigations were carried out using a P D M T B sample with Mu, 1.2 × 105. X-ray photographs of this polymer at room temperature in the solid state before and after melting consist of a number of diffraction rings. Table 2 shows interplanar distances d for this polymer. Slight differences in interplanar distances before melting and after melting crystallized samples point to the formation of similar crystalline modifications. On heating a sample to 500-510 K the polymer melts. Figure 4a shows the X-ray photograph of P D M T B at 530°K. The X-ray diffraction pattern consists of a sharp ring in the central part of the X-ray photograph with d ~ 3 0 . 3 × 10 -l° m which is due to the long recurrent chain segment of P D M T B molecules and two diffusion halos -- one very weak with d~9-1-8.7 × 10 -1° and the other -- more intense with d~-4.9 × 10 -1° m. This form of diffraction pattern m a y be explained b y the formation of a defective laminated structure produced b y recurrent chain
FIG. 4. X-ray photographs of PDMTB samples; a--melt at 530°K; b--crystalline orientated sample; c --orientated sample in the liquid-crystalline state at ~i20°K; d -- crystalline sample orientated by a magnetic field.
1258
A. I. G~mo~'~v ~ aZ.
segments in liquid-crystalline domains oriented at random in space. At 550 K no light passes through crossed Nicols, tahe X-ray photograph shows a halo in the range of large angles with d=5.3-5.0 × 10-z° m characterizing average distances between chain segments. All this indicates t h a t the system changes int~) the isotropic state. On cooling the melt rapidly with subsequent elongation and annealing (for 2 hr at 470°K) PDMTB molecules undergo orientation and crystallization (Fig. 4b). Projection of the recurrent chain segment on the molecular axis, determined from the distance between laminar lines is 32.2× 10 -lo m. We calculated the projection of the length of recurrent chain segment onto the maeromolecular axis for a fully elongated PDMTB macromolecule and obtained a value of 33.4 × × 10 -1° m. Comparison of this value with the experimental one indicates that molecules in the crystalline state have a practically completely elongated chain conformation. Figure 4c shows the X-ray photograph of a PDMTB sample previously oriented at 520 K. Two narrow reflexions with d ~ 30.4 × 10 -10 and 15.2 × 10 -lo m are observed on the meridian and a halo with d ~ 4 . 8 × 10 -10 m with increased intensity on the equator. Comparison of the value of 30.4× 10-Z0m in the mesomorphous state with the value of 32.2 × 10 -10 m in the crystalline state points to the formation in the mesomorphous state of a somewhat more folded chain conformation. On melting PDMTB in a magnetic field strength H = 1 T the liquid-crystalline domains undergo orientation, with subsequent slow cooling of the sample to recrystallized in the oriented state (Fig. 4d). However, the angle of orientation of molecular axes in relation to the magnetic field differs from the orientation of axes in elongation in a chemical field. A study was carried out recently [5] of a thermotropic liquid-crystalline polymer prepared from 4,4'-dihydroxy-a,w-diphenoxyalkane and terephthalic acid forming a nematic phase in the melt. This polymer differs from PDMTB, with a defecture laminar structure in the melt, by the absence of carbonyl groups from both ends of the mesogenic groups. Hence it follows that replacement of oxygen for the ester group results in stronger molecular interaction and affects the type of mesomorphous structure formed. Tranalated by E. SE~ERE
REFERENCES
1. A. I. GROGOR'YEV, N. A. ANDREYEVA, A. Yu. BIIJRIN, S. S. SKOROKHODOV and V. Ye. ESKIN, Vysokomol. soyed. B22: 891, 1980 (Not translated in Polymer Sol. U.S.S.R.) 2. W. H. STOCKMAYER and M. FIXMAN, J. Polymer Sci. C, 1, 137, 1963 3. T.M. BIRSHTEINp B. I. KOLEGOV and A. N. GORYUNOV, Tez dokl. na IV Mezhdunarodn. konf. sots. stran po zhidl~m kristallam, p. 146, Tbilisi. 1981
Determining t h e phase structure of fluoroplastics
1259
4. L. A. VOLKOVA, A. I. GRIGOR'YEV, N. A. ANDREYEVA, A. F. PODOL'SKH, N. G. ORLOVA a n d V. Ye. ESKIN, Vysokomol. soyed. A22: 1393, 1980 (Translated in P o l y m e r Sci. U.S.S.R. 22: 6, 1532, 1980) 5. S. ANTOUN, R. W. LENS and J. I. JIN, J. P o l y m e r Sei., P o l y m e r Chem. Ed. 12: 8, 1901, 1981
Polymer Science U.S.S.R. Vol. 25, No. 5, pp. 1259-1264, 1983 Printed in Poland
0032-3950]83 $10.00 + . 0 0 © 1984 Pergamon Press L i d .
DETERMINING THE PHASE STRUCTURE OF FLUOROPLASTICS USING THE NMR FREE INDUCTION SIGNAL* A. N. TEMNIKOV, V. D. FEDOTOV, V. M. LOGUNOVand E. E. FINKEL' All-Union Scientific Research I n s t i t u t e for the Cable I n d u s t r y
(Received 19 JFebruary 1982) Multi-component analysis was carried out in the temperature range of -- 120-120: of the free induction signal of three industrial fiuoroplastics: F-2, F-2M and F-42. Results were examined within the framework of a three-phase model of poly3rLer structure.
MA~y papers deal with the structure of fluoroplastics, including those describing the study of methods of X-ray diffraction and electron diffraction. A det'.dled investigation [1] was therefore carried out of their crystalline structure: element~ry cell parameters and three-dimensional groups of crystals, conformation and packing coefficients of molecules in crystals were determined. At the same time information concerning the phase structure of these polymers is limited; values of erystallinity K [2, 3] are normally only reported. On the other hand, it is known that the NMR pulse method in view of specific features may, in some cases, give more detailed information about phase structure. It was shown [4, 5] in a study in P E and P E T P that for the entire series of results of NMR pulse experiments in partially crystalline polymers a three-phase structural model should be used, including crystalline, amorphous and intermediate phases. I~ was established in these studies tha~ detailed information about the phase structure can be obtained in the simplest way by multi-component analysis of the free induction signal (FIS), which is based on the following principles. 1) to each structural phase a certain FIS component corresponds, the relative intensity of which P is equal to * Vysokomol. soyed. A25: No. 5, 1086-1089. 198~.
1253
REFERENCES 1. P. J. FLORY, Principles of Polymer Chemistry, p. 12, 68, Cornell University Press, Ithaca, New York, 1953 2. V. V. KORSHAK and S. V. VINOGRADOVA, Ravnovesnaya polikondensatsiya (Equilibrium Polycondensation). p. 38, 132, Nauka, Moscow, 1968 3. B. A. ZAITSEV and R. F. gI~ELEVA, Vysokomol. soyed. A23: 1783, 1981 (Translated in Polymer Sci. U.S.S.R. 23: 8, 1957, 1981) 4. B. A. ZAITSEV, G. I. ]{HRAMOVA and L. L. DANTSIG, Vysokomol. soyed. A24: 2467, 1982 (Translated in Polymer SoL U.S.S.R. 24: 12, 2831, 1982) 5. M. J. RHOAD and P. J. FLORY, J. Amer. Chem. Soc. 75: 5, 2216, 1950 6. B. A. ZAITSEV, L. L. DANTSIG, O. I. KHRAMOVA and G. A. SHTRAIKHMAN, Zh. prikl, khimii 50: 2, 411, 1977 7. A. M. TOROPTSEVA, K. V. BELGORODSKAYA and V. M. BONDARENKO, Laboratornyi praktikum pc khimii i tekhnologii vysokomolekulyarnykh soyedinenii, p. 125, Khimiya, Leningrad, 1972 8. L. B. SOKOLOV, Polikondensatsionnyi metod sinteza polimerov (Polycondensatioa Method of Polymer Synthesis), p. 35, 65, Khimiya, 1966
Polymer Science U.S.S.R. ~ol. 25, No. 5, lap. 1253-1259,1983 Printed in Poland
0032-3950]83 $10.00+.0@ C) 1984 Perga~non Press Ltd.
MOLECULAR PROPERTIES AND PHASE CONDITIONS OF POLYMERS WITH MESOGENIC GROUPS IN THE MAIN CHAIN* A. I. GRIGOR'YEV, N. A. ANDREYEVA,A. YU. BILIBIN, S. S. SKOROK~ODOVand V. Y~.. E s x ~ Institute of High-Molecular Weight Compounds, U.S.S.R. Academy of Sciences
(Received 9 February 1982) A study was made of molecular properties and phase conditions of polydecamethylene terephthaloyl di-p-oxybenzoate containing mesogenic groups in the main chain. It was shown that this polymer in melt changes into the liquid-crystalline state with the formation of a defective laminated structure.
WE studied previously [1] morphological properties of a polymer containing mesogenie groups in the main chain, separated by flexible polymethylene bypasses--poly-p-phenylenesebaeyl-di-p-oxybenzoate (PPSB) synthesized from hydroquinone. It was established that liquid-crystalline order is established in the melt of this polymer. * Vysokomol. soyed. A25: 1~o. 5, 1082-1085, 1983.
A . I . G m o o ~ ' ~ v t~ a/.
1254
I n this s t u d y we c o n t i n u e d t o e x a m l n e p o l y m e r s with mesogenie groups in t h e m a i n chain using p o l y d e c a m e t h y l e n e terephthaloyldi~o-oxybenzoate ( P D M T B )
--,CH, I,
2/10
it ~ 0
II ~ 0
--~'/"
11
0
c--o--1,
It 0
| ~n
p r e p a r e d from t e r e p h t h a l i c acid. Polymers with different intrinsic viscosity values were synthesized by polycondensation of 4,4-bis-(chlorocarbonylphenylene)terephthalate with decamethylene glycol in diphenyloxide at 473°K. Polymers with a viscosity of less than 0.2 m3/kg were prepared with non-equimolecular ratios of dichloranhydride and glycol. Synthesis of polymers will be described in detail in subsequent publications. Investigations were carried out in solution, in the solid state and in melts at different temperatures by light scattering, X-ray and viscometry. Intrinsic viscosity values of solutions in trifluoroacetic acid (TFAA) were measured using an Ubbelohde viscometer at 298°K, molecular weights Mw and second virial coefficients A2 by light scattering using a photoelectric nephelometer (PPS-2). The refractive index increment was determined from the formula
tin~do= ~ (n-- no), where v is the partial specific volume of the polymer, n and n0--refractive indices of the polymer and solvent (n was determined by immersion). Molecular parameters of PDMTB determined in TFAA solutions are given in Table 1. From the curve showing the dependence of log [~] on log Mw (Fig. 1) coefficients K~ and a were determined in the Mark-Kuhn-Houwink equation [~]----K~.M =. Kv=8"5
X 10 -s
a=0.65
0.4 0.2 0 -0.2 -0.4 I
q.2
I
I
q.6
I
I
I
I
5.4/o#M
FIe. 1. Dependence of log [~] on log Mw for PDMTB samples in TFAA. E x t r a p o l a t i n g t h e c u r v e showing the d e p e n d e n c e of [~]/M*----f(M~) t o M = 0 , a c c o r d i n g to t h e S t o c k m a y e r - F i x m a n e q u a t i o n [2], we d e t e r m i n e d t h e value o f Ko=F(~/M) t, where h0~ is t h e average square o f u n p e r t u r b e d dimensions o f spheres, F - - F l o r y c o n s t a n t equal ~o 2.1 × 10=Smole -1 (Fig. 2). H e n c e r e l a t i v e u n p e r t u r b e d dimensions (h~/M)*----1.2× 10 -1° m, which in order o f m a g n i t u d e ~orresponds t o u n p e r t u r b e d dimensions o f o r d i n a r y flexible-chain p o l y m e r s .
Polymers with mesogenic groups in the main chain TABLE I. MOLEOULA~ P A ~ Z T E R S , TRANSITION INTO
PDMTB samples
[t/],m'/kg
~eT.Tn~o POINTS AND TEMPERATURES OF
ISOTROPIC STATE OF
TJU..~
.M~ X 1 0 - ~
PDMTB s~PLES
A, X I0',
Ti, K
~[Tmelt, g
m'.mole/kgi
6.0 2"8 1"8 2.8
0.15 0.5 1.2 1.4
0.04 0-11 0"16 0.20
1255
523 543 543
478 503 503
Conformation statistics were used for polymers of similar chemical structure t o calculate the length of Kuhn segment A----28X 10-z° m [3]. Using the length o f the recurrent unit of the chain 32.2 x 10 -1° m, obtained from X-ray results the statistical segment of the chain may be calculated for PDMTB macromoleeules in TFAA, where L is the entire chain length. I t appears t h a t _4----24 × 10 -z° m. Therefore, theoretical calculation [3] agrees with experimental results.
A=-h]/L
T_~l'l~m 15-
:rq
11,41/z~10a 6 L
12-
5
9
q
6
,3
3 1
1
I
1
2
3 t,ll/Z,lO -ttz
FIG. 2
I
I
503
~23
]
5q3 T,K
FIG. 3
FIG. 2. Dependence of [~]/M* on M + for PDMTB samples in TFAA. FZG. 3. Dependence of the intensity of light passing through crossed Nicols on temperature for sample 2 (PDMTB) (rate of heating the sample being 1 deg/min). Melting points and temperatures of %Tansition of polymers into the isotropic state were determined using an M-21 mirror galvanometer according to the in, tensity of light passing through crossed Nicols in a device of the type previously described [4]. Samples were melted between two cover glasses placed inside the terminal of an electric oven. Figure 3 shows the course of intensity curve of light passing through crossed Nieols, according to temperature for sample 3 of PDMTB.
1256
A.I.
T~sL~ 2. ~
A
~
GBmo~Y~.v e~ a/.
DISTANCESd FOB SA~rp~ 3 (PDMTB) AT DIFFERENT TF~JPEBAk't~ES
T, K
293 (before melting) 528
d × 101° m 47.8 4.44 30.3
25-8 4.10 9.1 (halo)
47.4 4.76
27-2 4.53
548 293 (after melting)
13"0 3"48 4"9 (halo) 5.0 (halo) 13.6 4.26
© |
FIO° 4a, b
8.80 3.48
6"38 3"18
5"61 3"02
4.76
9"43 3.96
7"98 3"71
5"55 3"43
5.18 3.14
Polymers with mesogenio groups in the main chain
1257
Table 1 shows melting points and temperatures of transition into the isotropic state of the samples examined. I t can be seen that with an increase in polymer MW, melting points and temperatures of transition into the iso~ropie state somewhat increase and reach a maximum value. For the samples examined the temperature range of existence of the mesomorphous phase is independent of MW. X-ray investigations were carried out using a P D M T B sample with Mu, 1.2 × 105. X-ray photographs of this polymer at room temperature in the solid state before and after melting consist of a number of diffraction rings. Table 2 shows interplanar distances d for this polymer. Slight differences in interplanar distances before melting and after melting crystallized samples point to the formation of similar crystalline modifications. On heating a sample to 500-510 K the polymer melts. Figure 4a shows the X-ray photograph of P D M T B at 530°K. The X-ray diffraction pattern consists of a sharp ring in the central part of the X-ray photograph with d ~ 3 0 . 3 × 10 -l° m which is due to the long recurrent chain segment of P D M T B molecules and two diffusion halos -- one very weak with d~9-1-8.7 × 10 -1° and the other -- more intense with d~-4.9 × 10 -1° m. This form of diffraction pattern m a y be explained b y the formation of a defective laminated structure produced b y recurrent chain
FIG. 4. X-ray photographs of PDMTB samples; a--melt at 530°K; b--crystalline orientated sample; c --orientated sample in the liquid-crystalline state at ~i20°K; d -- crystalline sample orientated by a magnetic field.
1258
A. I. G~mo~'~v ~ aZ.
segments in liquid-crystalline domains oriented at random in space. At 550 K no light passes through crossed Nicols, tahe X-ray photograph shows a halo in the range of large angles with d=5.3-5.0 × 10-z° m characterizing average distances between chain segments. All this indicates t h a t the system changes int~) the isotropic state. On cooling the melt rapidly with subsequent elongation and annealing (for 2 hr at 470°K) PDMTB molecules undergo orientation and crystallization (Fig. 4b). Projection of the recurrent chain segment on the molecular axis, determined from the distance between laminar lines is 32.2× 10 -lo m. We calculated the projection of the length of recurrent chain segment onto the maeromolecular axis for a fully elongated PDMTB macromolecule and obtained a value of 33.4 × × 10 -1° m. Comparison of this value with the experimental one indicates that molecules in the crystalline state have a practically completely elongated chain conformation. Figure 4c shows the X-ray photograph of a PDMTB sample previously oriented at 520 K. Two narrow reflexions with d ~ 30.4 × 10 -10 and 15.2 × 10 -lo m are observed on the meridian and a halo with d ~ 4 . 8 × 10 -10 m with increased intensity on the equator. Comparison of the value of 30.4× 10-Z0m in the mesomorphous state with the value of 32.2 × 10 -10 m in the crystalline state points to the formation in the mesomorphous state of a somewhat more folded chain conformation. On melting PDMTB in a magnetic field strength H = 1 T the liquid-crystalline domains undergo orientation, with subsequent slow cooling of the sample to recrystallized in the oriented state (Fig. 4d). However, the angle of orientation of molecular axes in relation to the magnetic field differs from the orientation of axes in elongation in a chemical field. A study was carried out recently [5] of a thermotropic liquid-crystalline polymer prepared from 4,4'-dihydroxy-a,w-diphenoxyalkane and terephthalic acid forming a nematic phase in the melt. This polymer differs from PDMTB, with a defecture laminar structure in the melt, by the absence of carbonyl groups from both ends of the mesogenic groups. Hence it follows that replacement of oxygen for the ester group results in stronger molecular interaction and affects the type of mesomorphous structure formed. Tranalated by E. SE~ERE
REFERENCES
1. A. I. GROGOR'YEV, N. A. ANDREYEVA, A. Yu. BIIJRIN, S. S. SKOROKHODOV and V. Ye. ESKIN, Vysokomol. soyed. B22: 891, 1980 (Not translated in Polymer Sol. U.S.S.R.) 2. W. H. STOCKMAYER and M. FIXMAN, J. Polymer Sci. C, 1, 137, 1963 3. T.M. BIRSHTEINp B. I. KOLEGOV and A. N. GORYUNOV, Tez dokl. na IV Mezhdunarodn. konf. sots. stran po zhidl~m kristallam, p. 146, Tbilisi. 1981
Determining t h e phase structure of fluoroplastics
1259
4. L. A. VOLKOVA, A. I. GRIGOR'YEV, N. A. ANDREYEVA, A. F. PODOL'SKH, N. G. ORLOVA a n d V. Ye. ESKIN, Vysokomol. soyed. A22: 1393, 1980 (Translated in P o l y m e r Sci. U.S.S.R. 22: 6, 1532, 1980) 5. S. ANTOUN, R. W. LENS and J. I. JIN, J. P o l y m e r Sei., P o l y m e r Chem. Ed. 12: 8, 1901, 1981
Polymer Science U.S.S.R. Vol. 25, No. 5, pp. 1259-1264, 1983 Printed in Poland
0032-3950]83 $10.00 + . 0 0 © 1984 Pergamon Press L i d .
DETERMINING THE PHASE STRUCTURE OF FLUOROPLASTICS USING THE NMR FREE INDUCTION SIGNAL* A. N. TEMNIKOV, V. D. FEDOTOV, V. M. LOGUNOVand E. E. FINKEL' All-Union Scientific Research I n s t i t u t e for the Cable I n d u s t r y
(Received 19 JFebruary 1982) Multi-component analysis was carried out in the temperature range of -- 120-120: of the free induction signal of three industrial fiuoroplastics: F-2, F-2M and F-42. Results were examined within the framework of a three-phase model of poly3rLer structure.
MA~y papers deal with the structure of fluoroplastics, including those describing the study of methods of X-ray diffraction and electron diffraction. A det'.dled investigation [1] was therefore carried out of their crystalline structure: element~ry cell parameters and three-dimensional groups of crystals, conformation and packing coefficients of molecules in crystals were determined. At the same time information concerning the phase structure of these polymers is limited; values of erystallinity K [2, 3] are normally only reported. On the other hand, it is known that the NMR pulse method in view of specific features may, in some cases, give more detailed information about phase structure. It was shown [4, 5] in a study in P E and P E T P that for the entire series of results of NMR pulse experiments in partially crystalline polymers a three-phase structural model should be used, including crystalline, amorphous and intermediate phases. I~ was established in these studies tha~ detailed information about the phase structure can be obtained in the simplest way by multi-component analysis of the free induction signal (FIS), which is based on the following principles. 1) to each structural phase a certain FIS component corresponds, the relative intensity of which P is equal to * Vysokomol. soyed. A25: No. 5, 1086-1089. 198~.