Polybutene-1. Unperturbed molecular dimensions at different temperatures of isotactic and atactic stereoisomers

European Polymer Journal, 1971, Vol. 7, pp. 303-316. Pergamon Press. Printed in England.

POLYBUTENE-1. U N P E R T U R B E D MOLECULAR DIMENSIONS AT D I F F E R E N T TEMPERATURES OF ISOTACTIC AND ATACTIC STEREOISOMERS G. MORAGLIO,* G. GIANOTTI,J" F. ZOPP~; and U. BONICELLI-~

(Received 15 June 1970) Abstract--By viscosity measurements in 0 solvents at various temperatures, values of unperturbed dimensions and of (d In r-~/dT) are calculated for isotactic and atactic polybutene-1. (d In ~o2/dT) values for the two stereoisomers are also calculated by measurements of [7/] in a good solvent at various temperatures, according to the theories of Flory-Fox, Kurata-Stockmayer-Roig and FloryFisk; the reliability of these theories is estimated. The conclusions are: (I) Both the atactic and isotactic polymer dimensions decrease with increase of temperature, over the range investigated; however, (d In roZ/dT)for isotactic polymer is greater than for atactic. (2) The variation of log K o with T for atactic polybutene cannot be represented by a straight line over a wide range of temperature; it tends to increase in the lower temperature region. A similar behaviour appears for isotactic counterpart. (3) At fairly low temperature (i.e. at room temperature or slightly higher), isotactic polybutene shows larger dimensions than atactic polymer of the same molecular weight. (4) At fairly high temperature (near the melting point of the bulk isotactic polymer), the dimensions of the two stereoisomers are practically the same.

INTRODUCTION SO,~E years ago we f o u n d

d In ro 2 dT

× 1 0 3 = - - 1.9_ ~ ' 0"2

(1)

for atactic polybutene, (1) by viscosimetric m e a s u r e m e n t s in e solvents. The following a s s u m p t i o n s were m a d e : (a) Validity of the relationship: ['q] = K0 M ~ ---- ~

M~

(2)

in 0 solvents, where Ko is i n d e p e n d e n t of or only slightly d e p e n d e n t on the n a t u r e of the solvent. (b) L i n e a r variation of log Ko with t e m p e r a t u r e in the range e x a m i n e d ( - - 4 6 ° to

+83°). C o r r e s p o n d i n g m e a s u r e m e n t s for the isotactic stereoisomer were impossible, the solutions of this p o l y m e r being unstable below 50°--60° in pseudo-ideal solvents; o n the other hand, polybutene-1 undergoes a r e m a r k a b l e degradation at temperatures * Istituto di Chimica Industriale del Politecnico, P.za Leonardo da Vinci 32, 20133 Milano, Italy. t Centro Ricerche Milano, Montecatini Edison S.D.A., Milano. ++Istituto di Chimica deUe Macromolecole del C.N.R., Milano. 303

304

G. MORAGLIO, G. GIANOTTI, F. ZOPPI and U. BONICELLI

above 140 °. This limited available range of temperatures may involve misinterpretation of the trend of the molecular dimensions with T: hence, it is necessary to confirm the measurements by an alternative method. In this work we first report measurements of root mean square end-to-end distance of isotactic polybutene-1, between 60 ° and 140° in pseudo-ideal solvents, and the value of the directly calculated parameter (d In ro2/dT); to confirm the value of this parameter, further values are then calculated by measuring b?] vs. T in a thermodynamically favourable solvent (toluene), and by applying the theories of Flory-Fox, (2.3) K u r a t a Stockmayer-Roig (4) and Flory-Fisk, (s) which are referred to as F 49, KSR and F 66, respectively. In addition to the values determined previously, (1.7) we report here a further value of unperturbed dimensions of atactic polybutene; consequently, the range o f temperatures is extended, and some features of the trend of the dimensions with T for this stereoisomer are noted. Furthermore, a comparison is made between (d In ro2/dT) directly found by measurements in 0 solvents and the value calculated from [,/] vs. T measurements for atactic polybutene in a good solvent: the reliability of the three theories cited above can be assessed. EXPERIMENTAL Samples and fractionations All isotactic polymer samples were prepared by solution polymerization in n-heptane at 70 °, with AI(C2Hs)2I and TiCl3 (ARA type of Stauffer) as catalysts. Crude polymers were first purified from catalytic residues and then treated to remove the possible atactic and stereoblock polymer fractions. For this purpose, a sample was extracted by boiling methylene chloride for 48 hr. The residual polymer was dried (sample F). Two other samples were purified by a 48-hr crystallization from 1"4% toluene solutions, at 35 °, under gentle stirring. These polymers, separated and dried, are referred to as samples M and S. Samples F, M and S were subjected to fractional precipitation, in a thermostated bath at 80 °, by dissolution in o-dichlorobenzene and precipitation with N-N'-dimethylformamide. Antioxidants were used to prevent degradation. The atactic polybutene sample was prepared by a polymerization at --202 with catalysts from V(Acctylacetonatc)a and Ai(C2Hs)aC1. A 0.5 Yotoluene solution of the polymer, purified from the catalytic residues, was gently stirred for several hours at --30 °. The polymer in the supcmatant solution was precipitated by methanol and dried (sample A). Sample A was then fractionated at 30 °, using toluene as solvent and methanol as non-solvent. The isotactic and atactic polymer fractions axe referred to by capital letters indicating the parent sample. The digits refer to the fractionation scheme, the first to the main fractionation, and the others in order to the successive rcfractionations. Solvents Solvents were dried and distilled in a laboratory fractionating column before use. Phenyl-~-naphthylamine (0" 05 ~ by weight) was added to prevent oxidation. Viscosity measurements I~sreux-Bischoff type viscometcrs were used: c6) their dimensions were such that kinetic ener~, effects were negligible. Osmotic measurements Osmotic measurements were performed by dynamic osmometry (Hewlett-Packard mod. 502) at I00 ° in n-hexadecane. Properly conditioned "Schleicher and Schnell'" type 08 membranes were used. The molecular weight of the atactic polybutenc fraction A 3222 was determined in toluene at 35".

Polybutene-1. Unperturbed Molecular Dimensions at Different Temperatures

305

Critical temperature of liquidphases separation Critical temperatures of liquid-liquid phase separation were determined by using a suitable apparatus in which small amounts of polymer solutions, of known concentration, were contained. A magnetic stirrer provided effective mixing. Access of atmospheric moisture was prevented by means of CaClz traps.

RESULTS A N D D I S C U S S I O N

Unperturbed molecular weight dimensions by measurements in 0 solvents The unperturbed dimensions of isotactic polybutene have been determined from viscosities in phenetole and anisole which were known to be pseudo-ideal solvents for the atactic stereoisomer, (t'v~ and which give stable solutions of isotactic polymer at temperatures above 60°; we also employed phenylether, which is a poor solvent for polybutene. VZ 0

0.01

002

61--

tO

0'03

1000

x

I03

6O 630

o

x IO3

59

58

57

I sotocfic polybutene-I in phenetole

~o4

>¢

-[~

3.00

2.9(

0

0!5

r

~-0

p

1.5

Fzo. I. (above) Binary phase diagrams for isotactic polybutene-I (molecular weights indicated~ and phenetole. (below) Plot of the reciprocal of the critical absolute temperature against molecular size function for the same fractions. E .PJ. 7/4--- B

306

G. MORAGLIO, G. GIANOTTI, F. ZOPP[ and U. BONICELLI

Figures 1, 2 and 3 report the binary phase diagrams for the three solvents and fractions of isotactic polybutene, for the determination of the O temperatures. Each figure also shows the appropriate plot of the inverse of critical mixing temperature Tc vs. x -+ -k (2x) -t (where x = (MO/V1); M and 0 are molecular weight and partial specific volume respectively, and Vt is molar volume of the solvent(8~). The intrinsic viscosities of five fractions of isotactic polymer were therefore measured for the O conditions, i.e. at 64.5, 89 and 148°: the results are reported in Table 1. By plotting on double logarithmic chart the data of [7] and M of Table 1, for each of the solvents, 0.5 is the slope of the resulting straight lines: this fact confirms the 0 conditions.

V2

0

0.01

0.02

0.03

1

l

[

87 _

86

o

2:590 X

I03

85

*-" 84

83

-

.~90 x I0~

82

Isotactic

polybutene-I

in onisole

2-9(

% 28C

2-?C 0

O.S

I0

'x + ~"x]

I.~

x 10 2

FIG. 2. (above) Binary phase diagrams for isotactic polybutene-1 (molecular weights indicated) and anisole. (below) Plot of the reciprocal of the critical absolute temperature against molecular size function for the same fractions.

Polybutene-1. Unperturbed Molecular Dimensions at Different Temperatures

307

v2

0.01 t 145

~

0.02 t

0

003 l

I03 ×103

(.3 o

....-

650 x 103 14.0

-

390 x 103

135 [ sotoctic :

in

polybutene - I

phenyl e t h e r

2 50

j x

l

_Jf

2.40

2"30

0.5

1.0 •

I

1.5

I

FIG. 3. (above) Binary phase diagrams for isotactic polybutene-1 (molecular weights indicated) and phenylether. (below) Plot of the reciprocal of the critical absolute temperature against molecular size function for the same fractions.

TABLE I . MOLECULAR WEIGHTS AND INTRINSIC VISCOSITIES [-q] OF FRACTIONS OF ISOTACTIC POLYBUTENE-1 IN VARIOUS SOLVENTS (['q] IN 100 c m 3 g - l ; MOLECULAR WEIGHTS BY OSMOMETRY IN n-HEXADECANE AT

100 °) Fractions

F F F F F

422 522 622 722 922

M

[r/] at 64"5 ° in phenetole

562,000 316,000 182,000 115,000 43,700

0-840 0-640 0"488 0"380 0-231

[~71at 89 ° in anisole 0"810 0-625 0"476 0-390 0-225

[~1 at 148 ° in phenylether 0-780 0-590 0.445 0-342 0-208

308

G. MORAGLIO, G. GIANOTTI, F. ZOPPI and U. BONICELLI v

0.01

0.02

l

t

0"03

138

o . . ~ 0 156

x

103

~ 0 8

x

103

1"~4 ¢.) o

350 x 103

132 - -

150 - -

128--

118x 103 126 - -

19_4--

Atactic polybutene-I in phenyl ether

2.55

~o

z.sc

2.45

2.40 1.0

•0

2.0

3.0

[~x+~'x]

x 102

Fro. 4. (above) Binary phase diagrams for atactie polybutene-1 (molecular weights indicated) in phenylether. (below) Plot of the reciprocal of the critical absolute temperature against molecular size function for the same fractions.

The M - M relationships, according to (2), can be calculated thus: isotactic polybutene

~

[r/] = 1-13 X 10 -3 M ~ (in phenetole at 64.5 °) [~7] = 1.11 X 10 -3 M + (in anisole at 89 °) [~7] = 1-03 × 10 -3 M ÷ (in phenylether at 148 °)

(3) (4) (5)

F o r the atactic c o u n t e r p a r t o f polybutene, 0 conditions were measured in phenylether: Fig. 4 reports the binodial curves for fractions o f p o l y m e r in this solvent, and the plot indicating 0 = 141 °. F o r some fractions o f atactic polybutene, intrinsic

Polybutene-l. Unperturbed Molecular Dimensions at Different Temperatures

309

viscosities were determined (see Table 2). The [~]-M relationship calculated in phenylether by the least-square method and those determined previously (1.7) are as follows:

atactic polybutene

[~7] = [7] [~7] = [7] = [,j]

I

1.33 1-13 i .05 1.08 1.04

x x x × ×

10 -3 10 -3 10 -3 10 .3 10 -3

M ÷ (in M* (in M ~ (in M ~ (in M ÷ (in

(6) (7)

toluene at --46 °) isoamylacetate at 23 °) phenetole at 61 °) anisole at 83 °) phenylether at 141 °)

(8) (9)

(10)

TABLE 2. MOLECULAR WEIGHTS AND INTRINSIC VISCOSITIES ['r/] OF FRACTIONS OF ATACTIC POLYBUTENE-[

(In]

rN 100 c m 3 g - ~ ; MOLECULAR WEIGHTS BY OSMOMETRY IN n-HEXADECANE AT

Fractions

A 22222

l-q] at 141 ° in phenylether M

A 3222

A 4222

100 °)

A 522

A 62

0" 865

0" 500

0' 314

0- 220

0-155

655,000

209,000*

86,500

49,000

25,000

* Molecular weight obtained also by osmometry in toluene at 35 °.

All the results of Eqns. (3)-(10) are displayed in Fig. 5, where all the data of Ko, defined by Eqn. (2), are plotted in a semilogarithmic diagram vs. T. Allowing for confidence limits for Ko so determined, some qualitative comments can be made: (1) The atactic and isotatic polymer dimensions decrease with increase of temperature, over the range investigated. (2) The variation of log Ko with T f o r atactic polybutene cannot be represented by a straight line over a wide range of temperatures; it tends to bend upward in the lower temperature region.

~.~5

2

C

A t a c t i c polybul'ene - I

o

[ s o t o c t i c polybutene

3.10 -12 x I0"3~ ~-o5

3.O0

T

T

I

'

r

r

-40

0

40

80

IZO

160

t,

F'IG. 5. Log

"C

KO, obtained from Eqn. (2), for fractions of atactic and isotactic polybutene-1, as a function of temperature (figures refer to (d In r ~ / d T ) values).

310

G. MORAGLIO, G. GIANOTTI, F. ZOPPI and U. BONICELLI

(3) At a fairly low temperature (i.e. at room temperatures or slightly higher) isotactic polybutene shows larger dimensions than atactic polymer with the same molecular weight. (4) At a fairly high temperature, near the melting point of the bulk isotactic polymer, the dimensions of the two stereoisomers are practically the same. On a quantitative basis, it is possible to calculate for the isotactic stereoisomer: d In

ro 2

dT

× 103 = - - 0 - 8 (isotactic polybutene-I in the range from ~ 60 ° to ,-, 150 °)

(11)

A single value cannot be given for the atactic polymer because of the curved plot as has been noted above. Disregarding the value at --46 °, we can write: d In ro 2 dT

× 103 = - - 0 . 4 (atactic polybutene-1 in the range ~ 20 ° to ~ 140 °)

(12)

Without taking into account the Ke value at 141 °, the previous result (I) is valid: this figure, therefore, must be regarded as an average value between --46 ° and + 8 3 ° . m

Determination of (d In ro2/dT) in a thermodynamically favourable solvent The different rheological theories on polymer dilute solutions in " g o o d " solvents generally lead to: [rl] = K0 M 1/2 ct' = ~

M z/2 ~'

(13)

where ct represents the ratio of a linear dimension of the statistical coil to the corresponding dimension of the unperturbed molecule, and y is a numerical constant. The theories do not agree in the expression of a in terms of molecular parameters. The first analytical approach by F l o r y - F o x (F 49) gives:(2.3~ a s -- a 3 = const z

(14)

where

The terms 0 and Vt are the partial specific volume of the polymer and the molar volume of the solvent respectively, ~t is an entropic parameter and 0 the Flory temperature. According to this treatment, in (13), Y = 3. Several years later a new approach was developed by K u r a t a - S t o c k m a y e r - R o i g (4~ (KSR). The result can be written: ~3 _ ~ = const g (c0 z

(16)

where 8a 3

g(~) = (3~2 + 1)3/2 F o r this theory, in (13), - / = 2-43.

(17)

Polybutene-1. Unperturbed Molecular Dimensions at Different Temperatures

311

More recently, another treatment was elaborated by Flory-Fisk (s) (F 66), where a is expressed as c: -- cO = const and

zh

(18)

h(z/aa) may be approximated by: h

----- 1 -r-0"969

1 -I- 10a3 ]

(19)

From (13), (14) and (15), the well known compact relationship can be obtained ¢9,1o) dlnro2 = (5 1 ) dln[~] dT -dT

(1-

1)[dln(g2/V1) 0 ] ~7 dT ÷ T(T -- 0)

(20)

Likewise, from (13), (I5), (16) and (17) concerned with (KSR) treatment, one obtains: dlnro z 2{[ f(a)2 ] d l n [ r l ] d T = 5 f(a) .43 dr

[ f(a) kf(a)-~?.43

] [dln(~2/V1) 1 dr

0 0)]}

(21)

+ T(Twhere

2 3 f(~) -----~2--~---1 ÷ 1 + ½ ~-2

(22)

By elaborating (13) and (15) in connection with the (18) and (19) of (F 66) theory, maintaining 7 = 3 in (13), it is possible to write: dT

=

-- ~ F(a)

dT

~-2 F(a)

dr

-k r ( r -

0) (23)

where F(a)-= l d - 6 . 4 6

(a z -

1)

1 + 10~/

-t-0.969

1 ,-4- 10~5 (24)

It can be seen that right-hand sides of Eqns. (20), (21) and (23) are composed of two terms which, after substituting the proper values for the parameters, generally appear of opposite sign. Reliable results for (d In roZ/dT)can be expected when the difference between the quoted terms falls outside the experimental error of each of them; this condition can be obtained particularly in good solvents in which lower values of the (d In [~7]/dT) and (O/T[T-O])parameters are achieved. Unfortunately, we cannot directly measure 0 temperatures in good solvents for the crystallization phenomena of the isotactic polymer; however, it is likely that 0 temperature for isotactic polybutene in toluene is not far from --46 °, that is the 0 temperature

312

G. MORAGLIO, G. GIANOTTI, F. ZOPPI and U. BONICELLI

for atactic stereoisomer. (~) This view is confirmed by 0 temperature measurements for isotactic and atactic polybutene, as can be seen above and in previous work (~ and by analogous measurements on the stereoisomers of polypentene-l. (~) Therefore, by measuring [rl] vs. T in toluene at relatively high temperatures, slight differences in 0 temperatures of the two stereoisomers become insignificant and Eqns. (20), (21) and (23) can be applied with some de~ee of confidence. In Fig. 6 we report, in a semilogarithmic plot, data of [,/] vs. T in toluene for three fractions of isotactic polybutene. The respective molecular weights were determined viscosimetrically in tetralin at I00 °, applying the [~7]-Mrelationship suitable for atactic fractions;(12~ recent results, (t3) in fact, substantiate our hypothesis(~2) that [,/]-M

Isotoctic fractions o f polybutene-I

J--------'~-~-""-

0.5~

O

~.J3-~

~

686 x 103

624x103

Z 0-4

0"3

505 x I0 ~

40

50

60

70

f,

80

90

lO0

*C

F[o. 6. Semilogarithmic plot of [,/] against temperature for fractions of isotactic polybutene-I (figures denote tool. wt.).

calibration for atactic and isotactic polybutene in tetralin at 100 ° are practically coincident. Calculations of (d In ro2/dT) were made at 60°. For this purpose, values of ~ were obtained from (13) with Ks from the extrapolation of data in 0 solvents as above. The value of [d In (v~/V1)/dT] was calculated from ~ and V1, at 40 ° and 80°; for the partial specific volume of isotactic stereoisomer, extrapolated data of the melted dry polymer were used; (~4) the density of toluene was that reported in literature. (~s) Table 3 shows, for each of the three fractions, the values of (d In ro2[dT) according to the theories quoted above, and the corresponding values of M and (d In [7/]/dT). The figures obtained for the variation of unperturbed end-to-end distance indicate that KSR theory gives unexpectedly high values; on the contrary, F 49 and F 66 theories gives acceptable results, the middle value being ~ --1-7.10 -3. This latter, although larger than that obtained from 0 solvents measurements, i.e. --0"8.10 -3, can be completely justified by an upward trend of the curve for isotactic stereoisomer as

Polybutene-l. Unperturbed Molecular Dimensions at Different Temperatures

313

happens for the atactic polymer: in this case, in fact, the value referring to pseudoideal solvents must be regarded more correctly as the value for the middle o f the range examined, i.e. ~ 100°; our calculations were performed for a temperature o f 60 °. TABLE3. VALUESoF MOLECULARWEIGHT, OF (d In [vl/dT) A~'¢OCALCULATEDVALUES o F (d In roZ/dT) AT 6 0 ° ACCORDING TO THE THREE QUOTED THEORIES, FOR ISOTACTIC POLYBUTENE-1 FRACTIONS

M2 Molecular weight x 10 -3 d In [~7]/dT x 103 103 x d l n r o 2 / d T [ ' F 4 9 4~KSR according to F 66

686 1"42s --1-7 --4- 1 -- 1"4

Fractions M 12

S 23

624 (1"85) (--1"5) (--5"7) (-- 1" 2)

305 1"393 --2"1 --5'3 -- I" 8

Equations (20), (21) and (23) were applied also to the case of atactic polybutene-1. F o r this purpose, data o f [7/] in toluene vs. T, taken from a previous work (v) and reported in Table 4, are plotted in Fig. 7. F r o m this plot, (d in [~7]/dT)= 2 . 4 2 . 1 0 .3 °C -1 at 50 °. At this temperature, we calculated a through Ko plotted in Fig. 5, and [d In (g2/V1)/dT] in a similar way as for the isotactic polymer, f r o m data o f a m o r p h o u s dry polymer " ~ and toluene density (1 ~) at 30 ° and 70 °. Table 5 summarizes the results. It can be noted that, also in this case, K S R treatment gives for (d In ro-'/dT) too large a value, which does not fit Fig. 5. F 49 and F 66 theories give, at 50 °, values o f (d In roZ/dT) between - - 1 . 2 . 1 0 -3 and - - 0 . 4 . 1 0 -3, perfectly consistent with the curved trend o f log Ke vs. T; by proceeding

Al'actic f r o c f i o n

of polybutene - I in "toluene

0.~,--

Z ~ o

0.1--

i zo

i 3o

r 4o t s

I 50

[ 6o

I 70

°C

FIG. 7. Semilogarithmic plot of [~/]against temperature for a fraction of atactic polybutene-1 (figure denotes mol. wt.).

314

G. MORAGLIO, G. GIANOTTI, F. ZOPPI and U. BONICELLI

TABLE4.

I,~sIc

VISCOSITIES VS. TEMPERATURE OF THE ATACTIC POLYBUTEI~-I FRACTION R

322(7~

([,71IN 100 crn3 g-t) t° [7] in toluene

20

30

40

50

60

70

I" 23t

I" 313

1"337

1- 367

1-40,

1"432

TABLE 5.

VALUES OF MOLECULAR WEIGHT, OF

(d In [r/]/dT) ANDCALCULATED(d In r~o/dT)AT50° ACCORDING TO THE THREE QUOTED THEORIES FOR ATACTIC POLYBUTENE-I R 3 2 2 FRACTION('r)

Molecular weight x 10-3 d In [,fl/dT x 103 f F 49 103 x d In r-~/dT ,{KSR according to ~.F 66

265 2"42 --0"7 --2-6 --0"5

thus, it seems that - - 0 . 7 5 . 1 0 -3 of F 49, which nearly is the mean value found with pseudo-ideal solvents, would be the most reliable result.

CONCLUSIONS On the basis of th.e results reported in the previous sections, (d In ro2/dT) for atactic polybutene-1 exhibits a threefold variation over the range of temperatures examined (AT = 200°). This situation appears to be virtually the same, from a qualitative point of view, for the isotactic counterpart. In addition, for isotactic polypentene-1, log Ko data in pseudo-ideal solvents probably must have to be interpreted as having an upward-bending trend at low temperatures instead of a linear one [see Fig. 9 in ref. (11)]. We think that the strong dependence of (d in roZ/dT) on T could be a more general feature. Some discrepancies in literature data may therefore be trivial, depending on the implicit hypothesis of (d In ro2/dT) being constant. The data reported here can also be useful to check the rheological thedries of dilute solutions of macromolecular substances. In this connection, we have observed that theories F 49 and F 66, when applied with correct values of the parameters, give results for (d In ro2/dT) consistent with the data of unperturbed dimensions in 0 solvents; KSR theory gives too large values, incompatible with the picture obtained in pseudoideal solvents. KSR theory as commonly applied to data of [~7] and M, gives Ko values nearly independent of the interaction with the particular solvent used, "6~ whereas F 49 theory, elaborated according to Flory-Schaefgen, "7~ gives values of K0 depending on the solvent in contrast with theoretical expectation. We are now examining F 66 theory from this point of view. The results will be published shortly.

Polybutene-1. Unperturbed Molecular Dimensions at Different Temperatures

315

REFERENCES (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17)

G. Moraglio, G. Gianotti and F. Danusso, Europ. Polym. J. 3, 251 (1967). P. J. Flory, J. chem. Phys. 10, 51 (1949). P. J. Flory and T. G. Fox, J. Am. chem. Soc. 73, 1904 (1951). M. Kurata, W. H. Stockmayer and A. Roig, J. chem. Phys. 33, 151 (1960). P. J. Flory and S. Fisk, J. chem. Phys. 44, 2243 (1966). V. DesretLx and J. Bischoff, Bull. Soc. chim. Belg. 59, 93 (1950). F. Danusso, G. Moraglio and G. Gianotti, Rc. Ist. Lomb. Sci. Lett. A.94, 566 (1960). P. J. Flory, Principles of Polymer Chemistry, Chapt. XIII. Cornell University Press, Ithaca, New York (1953). P. J. Flory, A. Ciferri and R. Chiang, J. Am. chem. Soc. 83, 1023 (1961). A. Ciferri, Trans. Faraday Soc. 57, 853 (1961). G. Moraglio and G. Gianotti, Europ. Polym. J. 5, 781 (1969). G. Moragiio, Chim. Ind. (Mllano) 44, 32 (1962). G. Gianotti, To be published. F. Danusso, G. Moraglio, W. Ghiglia, L. Motta and G. Talam/ni, Chim. Ind. (Milano) 44, 32 (1962). J. Timmerman, Physicochemical Constants of Pure Organic Compounds. Elsevier (1950). M. Kurata and W. H. Stockmayer, Fortschr. Hochpolymeren Forsch. 3, 196 (1963). J. R. Schaefgen and P. J. Flory, J. Am. chem. Soc. 70, 2709 (1948).

R6sum6----A partir de mesures viscosim6triques darts des solvants ~ diverses temp6ratures, on calcule les valeurs des dimensions non perturbees et de (d In ro2/dT) pour les poly but-l-~ne isotactique et atactique. Les valeurs de (d In ro:/dT) des deux st6rdoisom6res sont 6galement calcul6es b. partir de mesures de [v] dans un bon solvant ~. diverses tempdratures, selon les th6ories de Flory-Fox, KurataStockmayer-Roig et Flory-Fisk : l'accord entre ces th6ories est examin6: Les conclusions sont les suivantes: (1) Dans le domaine &udi6 les dimensions des potym6res atactique et isotactique ddcroissent lorsque la temp6rature s'616ve; dans tousles cas (d In roZ/dT) est plus grand pour le polym&e isotactique que pour l'actactique. (2) La variation de log Ko avec Tne peut pas, dans te cas du polybut6ne atactique, 6tre reprdsent6e lin6airement dans un grand domaine de tempdrature; elle tend ~t &re plus importante dans la r6gion des plus basses temp6ratures. Un comportement semblable est observ6 pour le polym&e isotactique. (3) Aux tempdratures relativement faibles (~. la temp&ature ambiante ou 16g6rement au-dessus), le polybut6ne isotactique a de plus grandes dimensions que le polym6re atactique de m6me masse mol6culaire. (4) Aux temp,~ratures relativement hautes (pr6s du point de fusion du polym6re isotactique en masse), les dimensions des deux st&6oisom6res sont pratiquement identiques.

Sommaritr---Si sono calcolati con m/sure di viscosith intrinseca in solventi 0 a diverse temperature, i valori delle dimensioni quadratiche medie non perturbate e di (d In roZ/dT) per il polibutene-i isotattico e atattico. Si sono inoltre calcolati i valori di (d In ro2/dT) per i due stereoisomeri con misuse di [v] in un buon solvente a diverse temperature, secondo le teorie di Flory-Fox, Kurata-Stockmayer-Roig e Flory-Fisk; l'attendibilith di queste teorie viene consequentemente stimata. Si 6 giunti alle seguenti conclusioni: (1) Le dimensioni del polimero atattico e isotattico decrescono al crescere della temperatura nel campo di temperature studiato; tuttavia (d In ro2/dT) per il polimero isotattico ~ maggiore di quello dell'atattico. (2) La variazione di log K o in funzione di Tper il polibutene atattico non pub essere rappresentata con un'unica retta in tutto il carnpo di temperature, in quanto tende ad irnpennarsi nella zona delle basse temperature. Analogo comportamento si osserva nello stereoisomero isotattico. (3) A temperatura piuttosto bassa (temperatura ambiente o leggermente superiore) le dimensioni del polibutene isotattico sono maggiori di quelle del polimero atattico di ugual peso molecolare. (4) A una temperatura piuttosto elevata (in prossimit~, del punto di fusione del polimero isotattico) le dimensioni dei due stereoisomeri sono praticamente uguali.

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G. MORAGLIO, G. GIANOTTI, F. ZOPPI and U. BONICELLI

Zusammenfassung--Durch Viskosit~tsmessungen in 8 L6sungen bei verschiedenen Temperaturen werden Werte f~tr ruhige Dimensionen und ffir (d In roZ,'dT)in Bezug auf isotaktisches und ataktisches Polybuten-1 berechnet. (d In r~/dT) Werte ffir die zwei Steroisomer werden auch gemass den Theorien von Flory-Fox, Kurata-Stockmayer-Roig und Flory-Fisk durch Messungen von [7] in einem guten L6semittel bei verschiedenen Temperaturen berechnet. Die ZuverI~.ssigkeit dieser Theorien wird gesch~tzt. Die Schlfisse shad: (1) Sowohl die ataktischen wie die isotaktischen Polymerdimensionennehmen ha dem untersuchten Bereich mit Zunahme der Temperatur ab, allerdings ist (d In roZ/dT) for isotaktische Polymer grSsser als for ataktische. (2) Die Variation von log Kemit T ffir ataktisches Polybuten kann nicht in einer geraden Linie fiber einen grossen Temperaturbereich dargestellt werden, er scheint ha dem niedrigeren Temperaturbereich zu steigen..~hnliches Verhalten scheint sich ffir das isotaktische Gegenstfick zu ergeben. (3) Bei ziemlich niedriger Temperatur (d.h. bei Raumtemperatur oder etwas darfiber), weist isotaktisches Polybuten grSssere Dimensionen als ataktisches Polymer yon demselben Molekulargewicht auf. (4) Die Dimensionea der zwei Steroisomer sind bei ziemlich hohen Temperaturen, (nahe dem Schmelzpunkt des isotaktischen Hauptteilpolymer), praktisch die Gleichen.