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The structure and relaxation transitions in linear polyethylene by impulse NMR and X-ray methods
T H E S T R U C T U R E A N D R E L A X A T I O N T R A N S I T I O N S IN LrNEAR POLYETHY1~ENE BY I M P U L S E N M R AND X - R A Y METHODS* V. D. FEDOTOV, YU. K . OVCHINNIKOV, N. A. ABDRASHITOVA
and N. N. Kuz'Mn~ S. M. Kirov Institute of Chemical Technology, Kazan L. A. Karpov Physical Chem~Rtry Research Institute
(Received 25 June 1976) Impulse NMR and X-ray d;ffraction methods have shown that the non-crystalline zones in linear PE (MwN 105) crystallized from the melt consist of two phases having differing molecular mohilities and densities. The quantitative evaluations of the amounts of the two phases by the two methods yielded the same result. I t has bean concluded from the spin-spin relaxation times and the second moments as a function of temperature that there is a complex ~-relaxation transition in the amorphous zones and a linl~ with tl~e ~-transition which takes place in the crystalline zones. The exist. ence of a fairly large (20%) intermediate phase has been found to have a strong effect on the ~.transition temperature.
Qurr~. a number of publications of NMR [1-4] and X-ray diffraction [5-7] studies deal with the problem of the structure present in the non-crystalline zones of P E and the molecular processes which take l~lace in the various polymer phases, but there is disagreement in the opinions. The aim of the work described here was to get information on the quantitative correlations of the various structural phases present in linear P E and about the relaxation phenomena which occur in them. T h e samples which were examined in this study had the characteristics listed in Table 1. EXPERIMENTAL
All the samples were annealed for 5 hr at 125°C. The determinations were carried out in an impulse NMR relaxometer [9] at 21 MHz proton resonance frequency in the --120 to 125°C temperature range. The decrease in transverse magnetization was determined from changes of the free induction signal (FIS) as a function of time after exposure to a 90 ° impulse spin system. The X-ray diffraction study made use of a DRON-1-5 diffractometer using CuK~-radiation; focusing was by means of a bent quartz monocrystal and the * Vysokomol. soyed. A19: No. 2, 327-332, 1977. 378
Structure and relaxation trmmifions in linear polyethylene
319
recording was by scanning. Sample I was ex&mined aIld the measurement method was the same as before [10]. The magnetization of P E is known to change non-exponentially [11]; an analysis of the shape of the FIS reduction curves (of which there are typical T~rm I. C~mRAO~S~CS OF SA~rpI~S Or m~c~a PE CH= per 1000 C Crystallization atoms
M~ X lO-s
Sample Hostalen (I) LPPE* (II) LPPE *(III)
10 2-3
1"0 0"5 0.5
2-3
=,t% (from density)
From the melt
67"5
~y
75
pt ~ m
It
0.955 0.964
From solution
* P E obtained ace. to the method de6cribed in [8]. t =--Degree of crystallization. "~
ones in Fig. 1) showed the FIS to be generally described in the studied temrature range by a function consisting of the sum of 3 terms: f(t)=lol exp ( - - T - - ~ ) -Fp=exp ( - - T - - ~ ) + p s e x p ( - - ~-~-~) cos bt,
(1)
in which Pl,~.,a relative charge on the components relaxing in various times
,V , N l/O
,F, 80
" 120
I
~0
t
x
1
80
t
I
120
"['[me, msec Fz(~-.
1. Typical curves of the magnetization drop in samples: a---I; b---II at temperatures of" a: 1--36; 2--90; 3--125°C; b: 1--30; 2--60; 3--103; 4--125°C.
T2; a and b, parameters linked with the second and fourth moments of the absorption line by [12]: M~=a~+b2; M4=3a4+6a~b~+b 4 (2) These 3 components of the signal are associated by us with the existence of a
V . D . l~Domov ~ ¢4.
~80
phases in the part-crystalline PE, namely the amorphous (1), intermediate (2) and crystalline (3). The observed FIS was separated into its components by a graphical method by using a consecutive subtraction of the component with the slowest drop. Our experimental FIS could be divided into separate components when the relaxation times of the protons in the non-crystalline phases were at least twice as long as those in the crystalline phase, T=3 (the T~8 of PE is about 8-10 ~sec). The FIS was found to be the sum of 3 well distinguishable components at above 80°C temperatures in the case of sample I, and above 125°C for sample II; no intermediate component could be detected for sample III. The signal could be fairly well divided into two components, i.e. for the amorphous and crystalline ]phases, at lower temperatures (up to 20°C). The intermediate component could :~ I',Y
~="/.z
~
o ~
o
8 o
~o o o~,_~x o_o.~x~ o~o I~ x %-~x--x-~x-x. . . . . .
ol
T~ r=~Z 0
0
,
^J
J. @~ @¢?
"
-lqO
-100
-50
ZO
60
100
T,°C
FIG. 2. The dependence of the second moments -~=, 2~/is,and of the line-shape parameters K, and Ks on temperature for samples: l--I; g--II; 3--III. n o t be distinguished from the third at these temperatures. The signal given by the amorphous-phase protons was indistinguishable at room temperature from t h a t given by the protons present in the crystalline phase; this is due to a Tsz reduction and the approach in shape of the component 1 signal to the Gaussian. The ~/~ and M4 values, as well as the line shape parameters K=~r-M4/M~, which were calculated for the FIS detected below --80°C, agreed well with those produced by the wide band method by other authors [13, 14]. There was also good agreement of these values with M2s, M48 and Ks, which had been calculated for the third component of the FIS above 20°C (Fig. 2). The values of P3 for the samples were similar to the crystallinity ~ determined from the density. A temperature above 20°C thus gives optimal conditions in our experiment for separating the complex NMR signal into those belonging to the individual polymer phases. We had already stated that the slowly descending component detected above 80°C in sample I is non~xponential and described well by the sum of two exponents which can be attributed to two separate parts of the amorphous phase having differing molecular mobilities. This non-exponential transverse magne° tization can be due, as is known, to the structural heterogeneity of the amorphous
Structure and relaxation transitions in linear polyethylene
381
l~hase [15], as well as to factors such as the MWD [8], the anisotropy of segmental movements [16], or the existence of a broad spectrum of correlation times [17]. The fact that the I~ value of component 1 (Fig. 3) remains the same throughout the whole temperature range, while the I0~ appearing at 80°C for componen~ 2 is practically equivalent to the decrease of the crystalline phase is in favour of correlation of components 1 and 2 with two different parts of the amorphous phase. I n other words, the intermediate phase appears as consequence of t h e protons which contributed to the crystalline phase signal at lower temperatures. Parallel with the NMR studies we also investigated the amorphous component of sample I by X-ray diffraction. We had already reported [10] that the scatter due to the non-crystalline component is of a complex type. The dependence o f the 28max position on the temperature is shown in ~]g. 4 for various azimuthal directions. The validity of using the parameter 28m~x to characterize the near order has been shown in earlier work [18]. The given dependence of the amorphous scatter is evidence for the existence of two non-orientated phase components in crystalline PE which have differing 2#rex positions, and thus also X-ray densities. 0.8 Ps---x. ._0.7 ~ :
~0 ~'0"3'"
"6 ;
×
-~_ ; -~ ~" _~.
o
× 0.2DL p , O n ,
I
~/0
~o j
I
i
I
80
I
1
I
J
I
12o T,°G
FIG. 3. The temperature dependence of density Pl and Pa for the samples: O - - I ; ×--II; e--III.
The first component is isotropic and determines the scatter at all angles of t h e azimuth. I t is correct to call it the "liquid" component as the progress of t h e 28mx as a function of temperature coincides with the scatter produced by liquid paraffins. The second component has a much denser packing (the maximum of t h e amorphous halo is situated near the 110 reflexion), and the scatter is concentrated round the equator as with crystal reflexions, although there is a larger textural angle of scatter (a corrcctior~\has been made to the equatorial halo, position for the isotropic component). The calculated results for the amounts of the various components are contained in Table 2 (C~r~t, omt, and Cam are the contents of crystalline, intermediate and liquid components). One can see tha~ the amount of the "liquid" component remained unchanged on heating, while that for the denser amorphouP
$82
V.D. FZDOTOVe~ a/.
eoml~onent increased simultaneously with a decrease of the amount of the crystalline component. The comparison of the results for the same sample by two methods makes it clear that the non-crystalline parts present in PE have an irregular structure ~t~8~°C
PlO'f
Tfz~SSC
1.10"4
8 I-
o.e - \
b
,Vo\ o.o-,k x
\o.2_ o\o ood
26,,,= 22 ~
x equ~oHenfn.
"
2
~'.~x,...
_
~
oo
,~ (aoh,opic • meHd.o/,/erdn.
2O
I
• meh~
I
100
200
2.5
300
2.7
z.a
~°K ~G.
4
a.l
a.a
I~'/T, "K
~IG. 5
Fie. 4. The temperature dependence of the intermolecular ma~ml~n position 20max. Retiexions:/--equatorial; 2--isotropic; 3mmeridional; 4--melt. FIG. 5. THe temperature dependences of the spin-spin relaxations: a - - T , ; b - - T , for the samples: l--I; 2--II; 3--III. and that any quantitative assessments of the contents of various phases in the polymer made b y the two methods are very similar (Table 2, Fig. 3). The differences in ratio of the components as a function of temperature are obviously associated with the characteristics of the methods and are the subject of further studies. TABLE 2. T H E AMOUNT 0]8' STRUC'~u~,ES AS GIVEN BY T~L~ X - R A Y DIFFRACTION ~ r J ~ O D
P, °0
oo..t., %
c~t., %
o.,~., %
18 80 115
80 75 70
10 15 20
10 10 10
Structure and relaxation transitions in linear polyethylene
383
The separations of the FIS made by us on various PE samples in the 20-125°C range make it possible to use the temperature dependence T~ to get information about the molecular processes which take place in the various phases of the polyIner.
One can see in Fig. 2 that the line shape parameters K and Ks remain the same for all the samples up to a temperature of 125°C, and that M2 equals the second moment of the undi~vided descending curve at temperatures below --80°C; as mentioned earlier, it does not change until 80°C is reached in the case of sample I, and 90-100°C in the case of samples II and III. There is a rapid T23 reduction at higher temperatures. The start temperatures of the second moment decrease, T~, are given in Table 3. TmaL~ 3. ACTIVATION~ar~aoiEs E, ~ PERATURES Sample
I II Ill
TYPICAL8
B: (T~,,)" i E:" (T,,) t
E. (T.),
kcal/mole
kcal/mole
11.44-2 11.84-2 11.64-2
4.8 3.6 4.3
10"3 --
Ta
T,, cC
80. 95 95
AND
~[~D TEM-
~I"B, °C
76 100 97
* E', (T,,)-high; t E", (T,,)--Iow temperature part.
The absence of any M~ and K changes below T~ with temperature can be taken as proof of the crystalline zones in linear PE not having any molecular movement in the cited temperature range which would have a large enough amplitude and a frequency larger than 105 Hz. Such movements appear only at high temperatures (above T~), as indicated by the decrease of the second moments. These movements can be attributed to an a-relaxation transition in the crystalline zones. T~, as a function of inverse temperature (Fig. 5) yielded kinked lines for all t h e studied samples: these lines consist of two linear parts, i.e. a low and high temperature one. The Tp temperatures at which there is the abrupt change in the slope of the T~I-IOa/Tresponse lines are contained in Table 3. The T~-IO3/T function is linear. The temperature dependences of T21 and T22 were used to calculate the activation energy Ea (Table 3), which is an "apparent" one owing to the effects on it of the correlation times distribution. The molecular movements which determine the course of the relaxation time T21 are associated with segmental movements in the amorphous zones of PE and can be called the fl-relaxation transition. The division into two parts of the temperature dependence of T2,, for which the activation energies differ by a factor of 2-3 (Table 3), and the appearance
$84
V.D. Fm)oTov e$ ~.
of an exponential component in the F I S at fairly high temperatures (>20°C, and above 70°C for sample III) are evidence for a complex t y p e of the p-relaxation transition being connected with the segmental movements in the amorphous parts of,PE; the reason for this complexity is probably the existence of several movement types. We shall, compare in conclusion the behaviour of the relaxation times and t h e density of the non-crystalline phases in the studied P E samples. Figure 3 makes it clear that the I~1 and P3 for samples II and I I I are practically independent of temperature and that no intermediate phase will form up to 125°C. It does form above 125°C in sample I I and its Iv2~0"06, while the phase appears in sample I at about 80°C and has p ~ 0 . 2 . As the difference between these samples is only in their mol.wt, and MWD, one is bound to conclude that the size of the intermediate phase depends on the MM and MWD. The comparison of the temperature dependences of the spin-spin relaxation and the second moments showed that the start temperature of the M~(T~) decrease and that at which the slope changes of the T~I-103/T°K response lines (Tp) (Table 3) practically coincide while with this temperature coincides for sample I the appearance of the intermediate phase. The activation energies E~ and Ea are also similar. The ~-relaxation therefore is connected with the p-relaxation and the t w o affect each other. The temperature dependences of T~I for the various samples (Fig. 5) shows t h a t of T2~ to be smaller for sample I I I than for I and II, and that the temperature of separating the amorphous phase from the total signal is 30-40°C higher than that for I and II. This indicates that the molecular movements are more inhibited (frozen) in the amorphous phase of sample I I I than in I and II. The fact that the T~ of sample I is 10-15°C lower than of I I and I I I is connected, in our opinion, with the existence of the intermediate phase in it. The authors thank G. P. Belov for the supply of the P E samples, A. I. Maklak o v and N. F. Bakeyev for valuable criticism of this work. Tran,e/~ed, ~ K , A..~.'r.T:~Z,,T REFERENCES
1. 2. 3. 4. 5. 6. 7. 8.
K. BERGMAN and K. NAWOTKY, Kolloid-Z. u. Z. Polymere 250: 1094, 1972 B. SCHNEIDER, H. PIVCOVA and D. DOSKOCILOVA, Macromolecules 5: 120, 1972 W. L. F. GOLZ and H. G. LACHMAN, Kolloid-Z u. Z. Polymere 247: 814, 1971 K. FUJIMOTO, T. NISHI and R. KADO, Polymer J. 3: 448, 1972 M. KOKYDO and R. ULLMAN, J. Polymer Sci. 45: 91, 1960 W. O. STATTON, J. Appl. Polymer Sei. 7: 803, 1963 A. H. WINDLE, J. Mater. Sci. 10: 252, 1975 N. P. PLATONOV, V. A. SHEVELOV and G. P. BELOV, Vysokomol. soyed. A16: 1879, 1974 (Translated in Polymer Sci. U.S.S.R. 16: 8, 2177, 1974) 9. G. M. KADIEVSKH, V. M. CHERNOV, A. Sh. AGISHEV and V. D. FEDOTOV, Sb.: Nekotorye voprosy fiziki zhidkosti (In: Some Problems of the Physics of Liquids.). Kazan', No. 5, 73, 1971
Synthesis of polyenes with sulphide groups
385.
10. Yu. K. OVgHINNIKOV, N. N. KUZ'MIN, G. S. MARKOVA and N. F. B/tKEYEV, Vysokomol, soyed. B18: 31, 1976 (Not translated in Polymer Sci. U.S.S.R.) 11. U. HAEFER.LEN, R. HAUSSER and F. NOACK, Z. Naturforsch. 18a: 689, 1963 12. V. D. KOREPANOV, Dissertation, 1970 13. H. THURN, Kolloid-Z. u. Z. Polymere 179: 11, 1961 14. H. G. OLF and A. PETERLIN, Kollold-Z. u. Z. Polymere 215: 97, 1967 15. V. D. FEDOTOV and V. M. CHERNOV, Dokl. Akad. Nauk SSSR 224: 891, 1975 16. J. P. COHEN ADDAD, J. Chem. Phys. 60: 2440, 1974 17. V. P. GRIGOR'EV, A. I. MAKLAKOV and V. S. DERINOVSKII, Vysokomol. soyed. 16: 737, 1974 (Not translated in Polymer Sci. U.S.S.R.) 18. Yu. K. OVCHINNIKOV, Ye. M. ANTIPOV and G. S. MARKOVA, Vysokomol. soyed. A17: 1806, 1975 (Translated in Polymer Sci. U.S.S.R. 17: 8, 2081, 1975) /
THE SYNTHESIS AND SOME OF THE PROPERTIES OF POLYENES WITH SULPHIDE GROUPS* V. I. KLIMOV, L. A. NAUMENKO, N. )/I. SNEGOVS~r~, V. 1~. BOGOLYUBOV a n d Y r . G. KRYAZHEV Petroleum Chemistry Institute, Tomsk, Siberian Branch of U.S.S.R. Academy of Sciences.
(Received 30 June 1976) The polycondensation of CCI~ in the presence of lithium and mercaptans (phenyl, butyl or propyl mercaptan) yielded polyenes with alkyl or aryl sulphides in the branches. The behaviour of these has been studied during heating. The sulphur conraining polyconjugated systems have been found to effectively inhibit thermal-oxidative degradations.
ALTHOUGH the chemistry of the polymers with conjugated bond systems (CBS) has made much progress in the last few years, polyenes with sulphide groups in the branches (polyene sulphides) have received little attention. Thermal polymerization of phenylthio-acetylene for example [1] yields CBS containing phenyl' sulphide groups. The synthesis of such acetylene monomers is however a laborious and multi-stage process. One of the aims of the work described here was therefore the development of a suitable synthesis method of polyenes with alkyl or aryl sulphide groups. An earlier communication [2] had outlined the synthesis possibility of polyenes containing hetero-atomic substituents by the polycondensation of simpler polyhalogen hydrocarbons in the presence of lithium and of hetero-atomic additions w h i c h are c a p a b l e o f f o r m i n g o r g a n o - l i t h i u m c o m p o u n d s . W e used s u c h a * Vysokomol. soyed. A19: No. 2, 333-338, 1977.
and N. N. Kuz'Mn~ S. M. Kirov Institute of Chemical Technology, Kazan L. A. Karpov Physical Chem~Rtry Research Institute
(Received 25 June 1976) Impulse NMR and X-ray d;ffraction methods have shown that the non-crystalline zones in linear PE (MwN 105) crystallized from the melt consist of two phases having differing molecular mohilities and densities. The quantitative evaluations of the amounts of the two phases by the two methods yielded the same result. I t has bean concluded from the spin-spin relaxation times and the second moments as a function of temperature that there is a complex ~-relaxation transition in the amorphous zones and a linl~ with tl~e ~-transition which takes place in the crystalline zones. The exist. ence of a fairly large (20%) intermediate phase has been found to have a strong effect on the ~.transition temperature.
Qurr~. a number of publications of NMR [1-4] and X-ray diffraction [5-7] studies deal with the problem of the structure present in the non-crystalline zones of P E and the molecular processes which take l~lace in the various polymer phases, but there is disagreement in the opinions. The aim of the work described here was to get information on the quantitative correlations of the various structural phases present in linear P E and about the relaxation phenomena which occur in them. T h e samples which were examined in this study had the characteristics listed in Table 1. EXPERIMENTAL
All the samples were annealed for 5 hr at 125°C. The determinations were carried out in an impulse NMR relaxometer [9] at 21 MHz proton resonance frequency in the --120 to 125°C temperature range. The decrease in transverse magnetization was determined from changes of the free induction signal (FIS) as a function of time after exposure to a 90 ° impulse spin system. The X-ray diffraction study made use of a DRON-1-5 diffractometer using CuK~-radiation; focusing was by means of a bent quartz monocrystal and the * Vysokomol. soyed. A19: No. 2, 327-332, 1977. 378
Structure and relaxation trmmifions in linear polyethylene
319
recording was by scanning. Sample I was ex&mined aIld the measurement method was the same as before [10]. The magnetization of P E is known to change non-exponentially [11]; an analysis of the shape of the FIS reduction curves (of which there are typical T~rm I. C~mRAO~S~CS OF SA~rpI~S Or m~c~a PE CH= per 1000 C Crystallization atoms
M~ X lO-s
Sample Hostalen (I) LPPE* (II) LPPE *(III)
10 2-3
1"0 0"5 0.5
2-3
=,t% (from density)
From the melt
67"5
~y
75
pt ~ m
It
0.955 0.964
From solution
* P E obtained ace. to the method de6cribed in [8]. t =--Degree of crystallization. "~
ones in Fig. 1) showed the FIS to be generally described in the studied temrature range by a function consisting of the sum of 3 terms: f(t)=lol exp ( - - T - - ~ ) -Fp=exp ( - - T - - ~ ) + p s e x p ( - - ~-~-~) cos bt,
(1)
in which Pl,~.,a relative charge on the components relaxing in various times
,V , N l/O
,F, 80
" 120
I
~0
t
x
1
80
t
I
120
"['[me, msec Fz(~-.
1. Typical curves of the magnetization drop in samples: a---I; b---II at temperatures of" a: 1--36; 2--90; 3--125°C; b: 1--30; 2--60; 3--103; 4--125°C.
T2; a and b, parameters linked with the second and fourth moments of the absorption line by [12]: M~=a~+b2; M4=3a4+6a~b~+b 4 (2) These 3 components of the signal are associated by us with the existence of a
V . D . l~Domov ~ ¢4.
~80
phases in the part-crystalline PE, namely the amorphous (1), intermediate (2) and crystalline (3). The observed FIS was separated into its components by a graphical method by using a consecutive subtraction of the component with the slowest drop. Our experimental FIS could be divided into separate components when the relaxation times of the protons in the non-crystalline phases were at least twice as long as those in the crystalline phase, T=3 (the T~8 of PE is about 8-10 ~sec). The FIS was found to be the sum of 3 well distinguishable components at above 80°C temperatures in the case of sample I, and above 125°C for sample II; no intermediate component could be detected for sample III. The signal could be fairly well divided into two components, i.e. for the amorphous and crystalline ]phases, at lower temperatures (up to 20°C). The intermediate component could :~ I',Y
~="/.z
~
o ~
o
8 o
~o o o~,_~x o_o.~x~ o~o I~ x %-~x--x-~x-x. . . . . .
ol
T~ r=~Z 0
0
,
^J
J. @~ @¢?
"
-lqO
-100
-50
ZO
60
100
T,°C
FIG. 2. The dependence of the second moments -~=, 2~/is,and of the line-shape parameters K, and Ks on temperature for samples: l--I; g--II; 3--III. n o t be distinguished from the third at these temperatures. The signal given by the amorphous-phase protons was indistinguishable at room temperature from t h a t given by the protons present in the crystalline phase; this is due to a Tsz reduction and the approach in shape of the component 1 signal to the Gaussian. The ~/~ and M4 values, as well as the line shape parameters K=~r-M4/M~, which were calculated for the FIS detected below --80°C, agreed well with those produced by the wide band method by other authors [13, 14]. There was also good agreement of these values with M2s, M48 and Ks, which had been calculated for the third component of the FIS above 20°C (Fig. 2). The values of P3 for the samples were similar to the crystallinity ~ determined from the density. A temperature above 20°C thus gives optimal conditions in our experiment for separating the complex NMR signal into those belonging to the individual polymer phases. We had already stated that the slowly descending component detected above 80°C in sample I is non~xponential and described well by the sum of two exponents which can be attributed to two separate parts of the amorphous phase having differing molecular mobilities. This non-exponential transverse magne° tization can be due, as is known, to the structural heterogeneity of the amorphous
Structure and relaxation transitions in linear polyethylene
381
l~hase [15], as well as to factors such as the MWD [8], the anisotropy of segmental movements [16], or the existence of a broad spectrum of correlation times [17]. The fact that the I~ value of component 1 (Fig. 3) remains the same throughout the whole temperature range, while the I0~ appearing at 80°C for componen~ 2 is practically equivalent to the decrease of the crystalline phase is in favour of correlation of components 1 and 2 with two different parts of the amorphous phase. I n other words, the intermediate phase appears as consequence of t h e protons which contributed to the crystalline phase signal at lower temperatures. Parallel with the NMR studies we also investigated the amorphous component of sample I by X-ray diffraction. We had already reported [10] that the scatter due to the non-crystalline component is of a complex type. The dependence o f the 28max position on the temperature is shown in ~]g. 4 for various azimuthal directions. The validity of using the parameter 28m~x to characterize the near order has been shown in earlier work [18]. The given dependence of the amorphous scatter is evidence for the existence of two non-orientated phase components in crystalline PE which have differing 2#rex positions, and thus also X-ray densities. 0.8 Ps---x. ._0.7 ~ :
~0 ~'0"3'"
"6 ;
×
-~_ ; -~ ~" _~.
o
× 0.2DL p , O n ,
I
~/0
~o j
I
i
I
80
I
1
I
J
I
12o T,°G
FIG. 3. The temperature dependence of density Pl and Pa for the samples: O - - I ; ×--II; e--III.
The first component is isotropic and determines the scatter at all angles of t h e azimuth. I t is correct to call it the "liquid" component as the progress of t h e 28mx as a function of temperature coincides with the scatter produced by liquid paraffins. The second component has a much denser packing (the maximum of t h e amorphous halo is situated near the 110 reflexion), and the scatter is concentrated round the equator as with crystal reflexions, although there is a larger textural angle of scatter (a corrcctior~\has been made to the equatorial halo, position for the isotropic component). The calculated results for the amounts of the various components are contained in Table 2 (C~r~t, omt, and Cam are the contents of crystalline, intermediate and liquid components). One can see tha~ the amount of the "liquid" component remained unchanged on heating, while that for the denser amorphouP
$82
V.D. FZDOTOVe~ a/.
eoml~onent increased simultaneously with a decrease of the amount of the crystalline component. The comparison of the results for the same sample by two methods makes it clear that the non-crystalline parts present in PE have an irregular structure ~t~8~°C
PlO'f
Tfz~SSC
1.10"4
8 I-
o.e - \
b
,Vo\ o.o-,k x
\o.2_ o\o ood
26,,,= 22 ~
x equ~oHenfn.
"
2
~'.~x,...
_
~
oo
,~ (aoh,opic • meHd.o/,/erdn.
2O
I
• meh~
I
100
200
2.5
300
2.7
z.a
~°K ~G.
4
a.l
a.a
I~'/T, "K
~IG. 5
Fie. 4. The temperature dependence of the intermolecular ma~ml~n position 20max. Retiexions:/--equatorial; 2--isotropic; 3mmeridional; 4--melt. FIG. 5. THe temperature dependences of the spin-spin relaxations: a - - T , ; b - - T , for the samples: l--I; 2--II; 3--III. and that any quantitative assessments of the contents of various phases in the polymer made b y the two methods are very similar (Table 2, Fig. 3). The differences in ratio of the components as a function of temperature are obviously associated with the characteristics of the methods and are the subject of further studies. TABLE 2. T H E AMOUNT 0]8' STRUC'~u~,ES AS GIVEN BY T~L~ X - R A Y DIFFRACTION ~ r J ~ O D
P, °0
oo..t., %
c~t., %
o.,~., %
18 80 115
80 75 70
10 15 20
10 10 10
Structure and relaxation transitions in linear polyethylene
383
The separations of the FIS made by us on various PE samples in the 20-125°C range make it possible to use the temperature dependence T~ to get information about the molecular processes which take place in the various phases of the polyIner.
One can see in Fig. 2 that the line shape parameters K and Ks remain the same for all the samples up to a temperature of 125°C, and that M2 equals the second moment of the undi~vided descending curve at temperatures below --80°C; as mentioned earlier, it does not change until 80°C is reached in the case of sample I, and 90-100°C in the case of samples II and III. There is a rapid T23 reduction at higher temperatures. The start temperatures of the second moment decrease, T~, are given in Table 3. TmaL~ 3. ACTIVATION~ar~aoiEs E, ~ PERATURES Sample
I II Ill
TYPICAL8
B: (T~,,)" i E:" (T,,) t
E. (T.),
kcal/mole
kcal/mole
11.44-2 11.84-2 11.64-2
4.8 3.6 4.3
10"3 --
Ta
T,, cC
80. 95 95
AND
~[~D TEM-
~I"B, °C
76 100 97
* E', (T,,)-high; t E", (T,,)--Iow temperature part.
The absence of any M~ and K changes below T~ with temperature can be taken as proof of the crystalline zones in linear PE not having any molecular movement in the cited temperature range which would have a large enough amplitude and a frequency larger than 105 Hz. Such movements appear only at high temperatures (above T~), as indicated by the decrease of the second moments. These movements can be attributed to an a-relaxation transition in the crystalline zones. T~, as a function of inverse temperature (Fig. 5) yielded kinked lines for all t h e studied samples: these lines consist of two linear parts, i.e. a low and high temperature one. The Tp temperatures at which there is the abrupt change in the slope of the T~I-IOa/Tresponse lines are contained in Table 3. The T~-IO3/T function is linear. The temperature dependences of T21 and T22 were used to calculate the activation energy Ea (Table 3), which is an "apparent" one owing to the effects on it of the correlation times distribution. The molecular movements which determine the course of the relaxation time T21 are associated with segmental movements in the amorphous zones of PE and can be called the fl-relaxation transition. The division into two parts of the temperature dependence of T2,, for which the activation energies differ by a factor of 2-3 (Table 3), and the appearance
$84
V.D. Fm)oTov e$ ~.
of an exponential component in the F I S at fairly high temperatures (>20°C, and above 70°C for sample III) are evidence for a complex t y p e of the p-relaxation transition being connected with the segmental movements in the amorphous parts of,PE; the reason for this complexity is probably the existence of several movement types. We shall, compare in conclusion the behaviour of the relaxation times and t h e density of the non-crystalline phases in the studied P E samples. Figure 3 makes it clear that the I~1 and P3 for samples II and I I I are practically independent of temperature and that no intermediate phase will form up to 125°C. It does form above 125°C in sample I I and its Iv2~0"06, while the phase appears in sample I at about 80°C and has p ~ 0 . 2 . As the difference between these samples is only in their mol.wt, and MWD, one is bound to conclude that the size of the intermediate phase depends on the MM and MWD. The comparison of the temperature dependences of the spin-spin relaxation and the second moments showed that the start temperature of the M~(T~) decrease and that at which the slope changes of the T~I-103/T°K response lines (Tp) (Table 3) practically coincide while with this temperature coincides for sample I the appearance of the intermediate phase. The activation energies E~ and Ea are also similar. The ~-relaxation therefore is connected with the p-relaxation and the t w o affect each other. The temperature dependences of T~I for the various samples (Fig. 5) shows t h a t of T2~ to be smaller for sample I I I than for I and II, and that the temperature of separating the amorphous phase from the total signal is 30-40°C higher than that for I and II. This indicates that the molecular movements are more inhibited (frozen) in the amorphous phase of sample I I I than in I and II. The fact that the T~ of sample I is 10-15°C lower than of I I and I I I is connected, in our opinion, with the existence of the intermediate phase in it. The authors thank G. P. Belov for the supply of the P E samples, A. I. Maklak o v and N. F. Bakeyev for valuable criticism of this work. Tran,e/~ed, ~ K , A..~.'r.T:~Z,,T REFERENCES
1. 2. 3. 4. 5. 6. 7. 8.
K. BERGMAN and K. NAWOTKY, Kolloid-Z. u. Z. Polymere 250: 1094, 1972 B. SCHNEIDER, H. PIVCOVA and D. DOSKOCILOVA, Macromolecules 5: 120, 1972 W. L. F. GOLZ and H. G. LACHMAN, Kolloid-Z u. Z. Polymere 247: 814, 1971 K. FUJIMOTO, T. NISHI and R. KADO, Polymer J. 3: 448, 1972 M. KOKYDO and R. ULLMAN, J. Polymer Sci. 45: 91, 1960 W. O. STATTON, J. Appl. Polymer Sei. 7: 803, 1963 A. H. WINDLE, J. Mater. Sci. 10: 252, 1975 N. P. PLATONOV, V. A. SHEVELOV and G. P. BELOV, Vysokomol. soyed. A16: 1879, 1974 (Translated in Polymer Sci. U.S.S.R. 16: 8, 2177, 1974) 9. G. M. KADIEVSKH, V. M. CHERNOV, A. Sh. AGISHEV and V. D. FEDOTOV, Sb.: Nekotorye voprosy fiziki zhidkosti (In: Some Problems of the Physics of Liquids.). Kazan', No. 5, 73, 1971
Synthesis of polyenes with sulphide groups
385.
10. Yu. K. OVgHINNIKOV, N. N. KUZ'MIN, G. S. MARKOVA and N. F. B/tKEYEV, Vysokomol, soyed. B18: 31, 1976 (Not translated in Polymer Sci. U.S.S.R.) 11. U. HAEFER.LEN, R. HAUSSER and F. NOACK, Z. Naturforsch. 18a: 689, 1963 12. V. D. KOREPANOV, Dissertation, 1970 13. H. THURN, Kolloid-Z. u. Z. Polymere 179: 11, 1961 14. H. G. OLF and A. PETERLIN, Kollold-Z. u. Z. Polymere 215: 97, 1967 15. V. D. FEDOTOV and V. M. CHERNOV, Dokl. Akad. Nauk SSSR 224: 891, 1975 16. J. P. COHEN ADDAD, J. Chem. Phys. 60: 2440, 1974 17. V. P. GRIGOR'EV, A. I. MAKLAKOV and V. S. DERINOVSKII, Vysokomol. soyed. 16: 737, 1974 (Not translated in Polymer Sci. U.S.S.R.) 18. Yu. K. OVCHINNIKOV, Ye. M. ANTIPOV and G. S. MARKOVA, Vysokomol. soyed. A17: 1806, 1975 (Translated in Polymer Sci. U.S.S.R. 17: 8, 2081, 1975) /
THE SYNTHESIS AND SOME OF THE PROPERTIES OF POLYENES WITH SULPHIDE GROUPS* V. I. KLIMOV, L. A. NAUMENKO, N. )/I. SNEGOVS~r~, V. 1~. BOGOLYUBOV a n d Y r . G. KRYAZHEV Petroleum Chemistry Institute, Tomsk, Siberian Branch of U.S.S.R. Academy of Sciences.
(Received 30 June 1976) The polycondensation of CCI~ in the presence of lithium and mercaptans (phenyl, butyl or propyl mercaptan) yielded polyenes with alkyl or aryl sulphides in the branches. The behaviour of these has been studied during heating. The sulphur conraining polyconjugated systems have been found to effectively inhibit thermal-oxidative degradations.
ALTHOUGH the chemistry of the polymers with conjugated bond systems (CBS) has made much progress in the last few years, polyenes with sulphide groups in the branches (polyene sulphides) have received little attention. Thermal polymerization of phenylthio-acetylene for example [1] yields CBS containing phenyl' sulphide groups. The synthesis of such acetylene monomers is however a laborious and multi-stage process. One of the aims of the work described here was therefore the development of a suitable synthesis method of polyenes with alkyl or aryl sulphide groups. An earlier communication [2] had outlined the synthesis possibility of polyenes containing hetero-atomic substituents by the polycondensation of simpler polyhalogen hydrocarbons in the presence of lithium and of hetero-atomic additions w h i c h are c a p a b l e o f f o r m i n g o r g a n o - l i t h i u m c o m p o u n d s . W e used s u c h a * Vysokomol. soyed. A19: No. 2, 333-338, 1977.