Natta / Danusso Stereoregular Polymers and Stereospecific Polymerizations

The Contributions of Giulio Natta and His School to Polymer Chemistry
1. Auflage 2013
ISBN: 978-1-4832-2386-5
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 488 Seiten

Stereoregular Polymers and Stereospecific Polymerizations: The Contributions of Guilio Natta and his School to Polymer Chemistry, Volume 1 covers the developments in understanding the reactions, nomenclature, and physico-chemical properties of polymers. This volume is composed of 82 chapters, and starts with surveys of the synthesis and crystal structure of polymers. Significant chapters are devoted to the characterization of crystalline polymers, with emphasis on the determination of their viscosity and molecular weight. Other chapters deal with stereospecific polymers of olefins, mechanism of stereospecific catalysis, reaction kinetics. This volume also considers the polymerization of synthetic elastomers and the copolymerization of olefins, as well as their reaction kinetics. The remaining chapters describe the X-ray characterization of isotactic polymers. This book is directed toward polymer chemists.

Autoren/Hrsg.

Natta, Giulio

Danusso, Ferdinando

Inhaltsverzeichnis

1;Front Cover;1
2;Stereoregular Polymers and Stereospecific Polymerizations: The contributions of Giulio Natta and his school to Polymer Chemistry;4
3;Copyright Page;5
4;Table of Contents;8
5;PREFACE;6
6;CHAPTER 1. CRYSTALLINE HIGH POLYMERS OF a-OLEFINS;24
6.1;REFERENCES;27
7;CHAPTER 2. A NEW CLASS OF POLYMERS OF a-OLEFINS WITH AN EXCEPTIONAL REGULARITY OF STRUCTURE;28
7.1;SUMMARY;28
7.2;SEPARATION OF THE CRYSTALLINE POLYMERS FROM THE
AMORPHOUS ONES AND THEIR PROPERTIES;30
7.3;LINEARITY OF THE MAIN CHAIN;33
7.4;X-RAY EVIDENCE OF THE EXCEPTIONAL STRUCTURAL
REGULARITY OF CRYSTALLINE POLYMERS;36
7.5;STRUCTURES OF THE CHAINS OF "ISOTACTIC" CRYSTALLINE
POLYMERS;38
7.6;REFERENCES;41
8;CHAPTER 3. THE CRYSTALLINE STRUCTURE OF A NEW TYPE OF POLYPROPYLENE;42
8.1;ABSTRACT;42
9;CHAPTER 4. THE CRYSTALLINE STRUCTURE OF ISOTACTIC POLYSTYRENE;44
9.1;ABSTRACT;44
10;CHAPTER 5. THE CRYSTALLINE STRUCTURE OF ISOTACTIC POLYSTYRENE;45
10.1;ABSTRACT;45
11;CHAPTER 6. NEW RESEARCHES IN THE FIELD OF OLEFINS;46
11.1;INTRODUCTION;46
11.2;RESEARCH ON THE CARBONYLATION OF OLEFINS, HYDROFORMYLATION;47
11.3;SYNTHESIS OF ACIDS AND THEIR ESTERS;54
11.4;SYNTHESIS OF BICARBONYL DERIVATIVES, STARTING FROM ACETYLENE;57
11.5;SYNTHESIS AND CHARACTERIZATION OF THE NEWPOLY-a-OLEFINS WITH AN EXCEPTIONAL REGULARITY OF STRUCTURE;59
11.6;SYNTHESIS AND CHARACTERIZATION OF CRYSTALLINE POLYMERS OF a-OLEFINS;62
11.7;MECHANICAL PROPERTIES OF THE ISOTACTIC POLYMERS;66
11.8;REFERENCES;72
12;CHAPTER 7. SYNTHESIS AND STRUCTURE OF SOME CRYSTALLINE POIYHYDROCARBONS CONTAINING ASYMMETRIC CARBON ATOMS IN THE MAIN CHAIN;74
12.1;ABSTRACT;74
13;CHAPTER 8. ISOTACTIC POLYMERS;75
13.1;DESCRIPTION OF ISOTACTIC POLYMERS;75
13.2;METHODS FOR THE SYNTHESIS OF ISOTACTIC POLYMERS;79
13.3;CHARACTERIZATION AND PROPERTIES OF ISOTACTIC POLYMERS;83
13.4;SYNDIOTACTIC POLYMERS;91
13.5;REFERENCES;98
14;CHAPTER 9. CRYSTALLINE POLYMERS OF BUTADIENE AND STRUCTURE OF I,2-POLYBUTADIENE;99
14.1;EXAMINATION OF THE ELECTRONIC DIFFRACTIONS;102
14.2;DETERMINATION OF THE STRUCTURE;104
14.3;REFERENCES;107
15;CHAPTER 10. THE CHAIN STRUCTURE OF CRYSTALLINE POLYVINYLISOBUTYL ETHER;108
15.1;ABSTRACT;108
16;CHAPTER 11. SYNTHESIS AND PROPERTIES OF CRYSTALLINE HIGH POLYMERS OF BRANCHED a-OLEFINS;109
16.1;ABSTRACT;109
17;CHAPTER 12. CRYSTALLINE STRUCTURE OF SOME ISOTACTC POLY-a-OLEFINS;110
17.1;ABSTRACT;110
18;CHAPTER 13. THE GEOMETRIC SHAPE OF SPIRALIZED CHAINS OF ISOTACTIC POLYMERS;112
18.1;ABSTRACT;112
19;CHAPTER 14. VISCOSITY NUMBER AND MOLECULAR WEIGHT OF FRACTIONATED ISOTACTIC POLYSTYRENE;113
19.1;ABSTRACT;113
20;CHAPTER 15. STEREOSPECIFIC POLYMERIZATION OF a-OLEFINS;114
20.1;REFERENCES;122
21;CHAPTER 16. THE STRUCTURE OF CRYSTALLINE I,2-POLYBUTADIENE AND OF OTHER "SYNDIOTACTIC" POLYMERS;123
21.1;ABSTRACT;123
22;CHAPTER 17. CRYSTALLINE STRUCTURE OF POLYPROPYLENE OXIDE;124
22.1;ABSTRACT;124
23;CHAPTER 18. CRYSTALLINE BUTADIENE POLYMER WITH AN ISOTACTIC I,2-ENCHAINMENT;125
23.1;ABSTRACT;125
24;CHAPTER 19. STEREOSPECIFIC CATALYSIS AND ISOTACTIC POLYMERS;127
24.1;STEREOISOMERY PHENOMENA IN VINYL HIGH POLYMERS;127
24.2;STEREOISOMERY PHEMOMENA IN CONJUGATED POLYDIOLEFINS;139
24.3;PROPERTIES OF STEREOSPECIFIC POLYMERIZATIONS;141
24.4;MECHANISM OF THE PROCESSES USED FOR STEREOSPECIFIC CATALYSIS;142
24.5;STEREOSPECIFIC CATALYSTS FOR ISOTACTIC POLYMERS;151
24.6;OTHER STEREOSPECIFIC CATALYSIS;155
24.7;CONCLUSIONS;156
24.8;REFERENCES;157
25;CHAPTER 20. THE CRYSTALLINE STRUCTURE OF THE NEW POLYMERS OF CONJUGATED DIOLEFINS WITH A TRANS-I,4 ENCHAINMENT;159
25.1;ABSTRACT;159
26;CHAPTER 21. CRYSTALLINE STRUCTURE OF CIS-I,4-POLYBUTADIENE AND OF CIS-I,4-POLYISOPRENE;160
26.1;ABSTRACT;160
27;CHAPTER 22. THE CRYSTALLINE STRUCTURE OF ISOTACTIC POLY-a-BUTENE;161
27.1;ABSTRACT;161
28;CHAPTER 23. SOME SOLUTION PROPERTIES OF ISOTACTIC AND ATACTIC POLYSTYRENES;162
28.1;ABSTRACT;162
29;CHAPTER 24. ISOTACTIC AND STEREOISOMERIC POLYMERS;163
29.1;ISOMERISM PHENOMENA IN ALIPHATIC HIGH POLYMERS;163
29.2;CRYSTALLINE STRUCTURE OF POLY-a-OLEFINS;166
29.3;CRYSTALLINITY OF ISOTACTIC POLYMERS;178
29.4;ATACTIC AND BLOCK POLYMERS;184
29.5;PROPERTIES OF STEREOISOMERIC MIXTURES, DIRECTLY OBTAINED BY THE POLYMERIZATION OF a-OLEFINS;189
29.6;STEREOISOMERIC POLYMERS OF DIOLEFINS;192
29.7;REFERENCES;199
30;CHAPTER 25. CRYSTALLINE STRUCTURE OF ISOTACTIC POLYPROPYLENE;201
30.1;ABSTRACT;201
31;CHAPTER 26. QUANTITATIVE DETERMINATION OF THE CRYSTALLINITY OF POLYPROPYLENE;202
31.1;ABSTRACT;202
32;CHAPTER 27. THE NATURE OF SOME SOLUBLE CATALYSTS FOR LOW-PRESSURE ETHYLENE POLYMERIZATION;203
32.1;REFERENCES;207
33;CHAPTER 28. ISOPHASIC DILATOMETRIC TRANSITIONS OF SOME POLY-a-OLEFINS;208
33.1;REFERENCES;211
34;CHAPTER 29. ISOTACTIC POLYERS;212
34.1;CRYSTALLINITY OF ISOTACTIC POLYMERS;216
34.2;STEREOSPECIFIC PROCESSES OF CATALYSIS;217
34.3;ATACTIC AND BLOCK POLYMERS;223
34.4;PROPERTIES OF MIXTURES OF STEREOISOMERS;226
34.5;DIOLEFIN STEREOISOMERIC POLYMERS;229
34.6;REFERENCES;232
35;CHAPTER 30. KINETICS OF THE STEREOSPECIFIC POLYMERIZATION OF PROPYLENE TO ISOTACTIC POLYMERS;234
35.1;ABSTRACT;234
36;CHAPTER 31. ISOTACTIC AND STEREOBLOCK POLYMERS OF PROPYLENE;235
36.1;SUMMARY;235
36.2;I. STEREOISOMERY ASPECTS IN THE LINEAR CHAINS OF POLYPROPYLENE;235
36.3;II. SEPARATION AND CHARACTERIZATION OF STEREOBLOCK POLYMERS OF PROPYLENE;238
36.4;III. EXPERIMENTAL PART;248
36.5;CONCLUSIONS;252
36.6;REFERENCES;254
37;CHAPTER 32. A CRYSTALLIZABLE ORGANOMETALLIC COMPLEX CONTAINING TITANIUM AND ALUMINIUM;255
37.1;REFERENCES;257
38;CHAPTER 33. STEREOSPECIFIC POLYMERIZATION OF a-OLEFINS. NOTE I;258
38.1;ABSTRACT;258
39;CHAPTER 34. STEREOSPECIFIC POLYMERIZATION OF a-OLEFINS. NOTE II.THE FIRST SYNTHESES OF LINEAR, ISOTACTIC AND NON-ISOTACTIC POLYMERS OF PROPYLENE;260
39.1;ABSTRACT;260
40;CHAPTER 35. STEREOSPECIFIC POLYMERIZATION OF a-OLEFINS, NOTE III. POLYMERIZATION OF PROPYLENE WITH CATALYSTS HAVING A DIFFERENT DEGREE OF STEREOSPECIFICITY;262
40.1;ABSTRACT;262
41;CHAPTER 36. NEW SYNTHETIC ELASTOMERS;264
41.1;NEW STEREOISOMERS OF POLYDIOLEFINS;265
41.2;a-OLEFIN POLYMERS;274
41.3;CONCLUSIONS;280
41.4;REFERENCES;281
42;CHAPTER 37. THE NATURE OF SOME SOLUBLE CATALYSTS FOR LOW-PRESSURE POLYMERIZATION OF ETHYLENE;284
43;CHAPTER 38. KINETICS OF CHAIN GROWTH AND TERMINATION PROCESSES IN THE STEREOSPECIFIC POLYMERIZATION OF PROPYLENE;285
43.1;ABSTRACT;285
44;CHAPTER 39. DILATOMETRIC PROPERTIES AND STRUCTURE OF THE ISOMERIC POLYMERS OF ETHYLENE AND OF a-OLEFINS;287
44.1;ABSTRACT;287
45;CHAPTER 40. COPOLYMERIZATION OF ETHYLENE WITH ALIPHATIC a-OLEFINS. NOTE I: PRELIMINARY STUDIES ON THE COPOLYMERIZATION OF ETHYLENE WITH PROPYLENE;288
45.1;ABSTRACT;288
46;CHAPTER 41. COPOLYMERIZATION OF ETHYLENE WITH ALIPHATIC a-OLEFINS. NOTE I I. THE COPOLYMERIZATION REACTIVITY RATIOS WITH CATALYSTS OBTAINED FROM ANADIUM OXYCHLORIDE AND ALKYLALUMINIUMS;290
46.1;ABSTRACT;290
47;CHAPTER 42. SCTEREOSPECIFIC CATALYSIS AND STEREOIS'O'MERIC POLYMERS. PREPARATION OF FIBRES PLASTICS AND NEW ELASTOMERS;291
47.1;INTRODUCTION;291
47.2;NEW PLASTICS;298
47.3;NEW FIBRES;301
47.4;NEW ELASTIC RUBBERS;304
47.5;POLYMERIZATION PROCESSES BY COORDINATED ANIONIC CATALYSIS AND STEREOSPECIFICITY;312
47.6;KINETICS OF THE STEREOSPECIFIC POLYMERIZATION OF a-OLEFINS;322
47.7;REFERENCES;327
48;CHAPTER 43. THE POLYMERIZATION OF PROPYLENE WITH CATALYSTS OBTAINED FROM TITANIUM TETRACHLORIDE. NOTE I: THE INFLUENCE OF THE TYPE OF ALKYLALUMINIUM ON THE POLYMERIZATION OF PROPYLENE;329
48.1;ABSTRACT;329
49;CHAPTER 44. THE POLYMERIZATION OF PROPYLENEWITH CATALYSTS OBTAINED FROM TITANIUM TETRACHLORIDE. NOTE II: CATALYSTS FROM ORGANOMETALLIC COMPOUNDS OF METALS OF THE I, II AND III GROUPS OF THE PERIODIC TABLE;331
49.1;ABSTRACT;331
50;CHAPTER 45. THE POLYMERIZATION OF PROPYLENE WITH CATALYSTS OBTAINED FROM TITANlUM TETRACHLORIDE. NOTE III: THE INFLUENCE OF TEMPERATURE
ON THE STEREOSPECIFICITY
OF THE POLYMERIZATION;333
50.1;ABSTRACT;333
51;CHAPTER 46. STRUCTURE OF AMORPHOUS, HIGH POLYMERS OF a-OLEFINS, WITH SPECIAL EMPHASIS ON POLYETHYLENE;334
51.1;ABSTRACT;334
52;CHAPTER 47. CRYSTALLIZABLE COMPLEXES OF TITANIUM AND AlUMINIUM WHICH ARE CATALYTICALLY ACTIVE IN THE POLYMERIZATION OF ETHYLENE;335
52.1;ABSTRACT;335
53;CHAPTER 48. STEREOSPECIFIC POIJYMERIZATION BY MEANS OF COORDINATED ANIONIC CATALYSIS;337
53.1;SUMMARY;337
53.2;INTRODUCTION;337
53.3;REFERENCES;357
54;CHAPTER 49. KINETICS OF PROPYLENE POLYMERIZATION WITH HIGHLY STEREOSPECIFIC HETEROGENEOUS CATALYSTS. NOTE I: OVERALL KINETICS OF THE POLYMERIZATION PROCESS;359
54.1;ABSTRACT;359
55;CHAPTER 50. KINETICS OF PROPYLENE POLYMERIZATION WITH HIGHLY STEREOSPECIFIC HETEROGENEOUS CATALYSTS. NOTE II: NATURE OF THE SETTLING PERIOD;360
55.1;ABSTRACT;360
56;CHAPTER 51. COPOLYMERIZATION OF ETHYLENE WITH ALIPHATIC a-OLEFINS. NOTE III: ETHYLENE-PROPYLENE COPOLYMERIZATION WITH CATALYSTS OBTAINED FROM VANADIUM TETRACHLORIDE;362
56.1;ABSTRACT;362
57;CHAPTER 52. THE MECHANISM AND KINETICS OF THE POLYMERIZATION OF a-OLEFINS;363
57.1;KINETICS ASPECTS OF THE POLYMERIZATION OF a-OLEFINS;363
57.2;REFERENCES;384
58;CHAPTER 53. THE CRYSTALLINE STRUCTURE OF ISOTACTIC 1,2-POLYBUTADIENE;385
58.1;ABSTRACT;385
59;CHAPTER 54. THE STEREOSPECIFIC POLYMERIZATION OF a-OLEFINS. NOTE IV: THE POLYMERIZATION OF PROPYLENE WITH TITANIUM CHLORIDES AND DIFFERENT TRIALKYLALUMINIUMS;386
59.1;ABSTRACT;386
60;CHAPTER 55. APPLICATIONS OF THE ELECTRON DIFFRACTION METHOD TO THE STUDY OF POLYMER STRUCTURES;388
60.1;ABSTRACT;388
61;CHAPTER 56. CRYSTAL STRUCTURE OF THE COMPLEX (C5H5)2TiC12A1(C2H5)2;389
62;CHAPTER 57. KINETICS OF PROPYLENE POLYMERIZATION WITH HIGHLY STEREOSPECIFIC HETEROGENEOUS CATALYSTS. NOTE III: CHAIN TERMINATION PROCESSES DEPENDING ON CATALYST CONCENTRATION;393
62.1;ABSTRACT;393
63;CHAPTER 58. KINETICS OF PROPYLENE POLYMERIZATION WITH HIGHLY STEREOSPECIFIC HETEROGENEOUS CATALYSTS. NOTE IV: INFLUENCE OF TEMPERATURE AND PRESSURE ON THE KINETICS OF GROWTH AND TERMINATION PROCESSES;394
63.1;ABSTRACT;394
64;CHAPTER 59. CRYSTALLINE STRUCTURE OF ORGANOMETALLIC COMPLEXES CONTAINING ALUMINUM AND TITANIUM;395
64.1;ABSTRACT;395
65;CHAPTER 60. ATACTIC AND STEREOBLOCK POLYMERS OF a-OLEFINS;397
65.1;ABSTRACT;397
66;CHAPTER 61. POLYMORPHISM OF CRYSTALLINE TITANIUM TRICHLORIDE;400
66.1;ABSTRACT;400
67;CHAPTER 62. CHROMATOGRAPHIC FRACTIONATION OF STEREOBLOCK POLYMERS;403
67.1;ABSTRACT;403
68;CHAPTER 63. KINETICS OF PROPYLENE POLYMERIZATION WITH HIGHLY STEREOSPECIFIC HETEROGENEOUS CATALYSTS. NOTE V: STUDY OF THE CHAIN TRANSFER PROCESSES WITH 14C LABELLED ALKYLALUMINUM COMPOUNDS;407
68.1;ABSTRACT;407
69;CHAPTER 64. POTENTIOMETRIC ANALYSIS OF ALUMINUM ALKYL COMPOUNDS;408
69.1;ABSTRACT;408
70;CHAPTER 65. ISOPHASIC TRANSITIONS OF POLYMERS OF n-ALIPHATIC a-OLEFINS;409
70.1;ABSTRACT;409
71;CHAPTER 66. A KINETIC INTERPRETATION OF THE STUDY OF THE FORMATION OF STEREOBLOCK POLYMERS;411
71.1;ABSTRACT;411
72;CHAPTER 67. STEREOSPECIFIC POLYMERIZATION OF STYRENE. NOTE I: INFORMATION AND PROBLEMS OF CRYSTALLINE POLYSTYRENES;412
72.1;ABSTRACT;412
73;CHAPTER 68. STEREOSPECIFIC POLYMERIZATION OF CONJUGATED DIOLEFINS. NOTE I: SYNTHESIS AND STRUCTURE OF TRANS-l,4 POLYDIOLEFINS;414
73.1;ABSTRACT;414
74;CHAPTER 69. STEREOSPECIFIC POLYMERIZATION OF STYRENE. NOTE II: FEATURES OF THE CATALYTIC SYSTEM TiC14-A1(C2H5) 3;420
74.1;ABSTRACT;420
75;CHAPTER 70. CONFORMATION OF LINEAR CHAINS AND THEIR MODE OF PACKING IN THE CRYSTAL STATE;421
75.1;SYNOPSIS;421
75.2;ISOTACTIC POLYMERS8;427
75.3;SYNDIOTACTIC POLYMERS9;431
75.4;CRYSTALLINE 1,4-POLYDIENESlo;432
75.5;REFERENCES;437
76;CHAPTER 71. STEREOSPECIFIC POLYMERIZATION OF CONJUGATED DIOLEFINS WITH CATALYSTS CONTAINING DIFFERENT TiC13 MODIFICATIONS;439
76.1;ABSTRACT;439
77;CHAPTER 72. POLYMERIZATION OF ETHYLENE WITH SOLUBLE CATALYSTS;441
77.1;ABSTRACT;441
78;CHAPTER 73. ISOTACTIC POLYMERS OF METHYL-SUBSTITUTED STYRENES;443
78.1;ABSTRACT;443
79;CHAPTER 74. X-RAY CHARACTERIZATION OF SOME NEW ISOTACTIC POLYMERS;444
79.1;ABSTRACT;444
80;CHAPTER 75. THE INTERPRETATION OF THE I.R. SPECTRUM OF ISOTACTIC POLYPROPYLENE;445
80.1;ABSTRACT;445
80.2;REFERENCES;446
81;CHAPTER 76. ISOTACTIC POLYMERS OF SILICON-CONTAINING VINYL MONOMERS;447
81.1;REFERENCES;449
82;CHAPTER 77. RADIOCHEMICAL DETERMINATION OF THE NUMBER OF ACTIVE CENTRES IN STEREOSPECIFIC POLYMERIZATION CATALYSTS;450
82.1;ABSTRACT;450
83;CHAPTER 78. KINETICS OF PROPYLENE POLYMERIZATION WITH HIGHLY STEREOSPECIFIC HETEROGENEOUS CATALYSTS. NOTE VI: DETERMINATION OF THE ACTIVE CENTRES BY KINETIC METHODS;453
83.1;ABSTRACT;453
84;CHAPTER 79. STEREOSPECIFIC POLYMERIZATIONS AND CATALYSIS;455
84.1;REFERENCES;484
85;CHAPTER 80. PROBLEMS CONCERNING THE VISCOSITY OF POLYPROPYLENES IN SOLUTION;485
85.1;ABSTRACT;485
86;CHAPTER 81. STEREOSPECIFIC POLYMERIZATION OF ACETYLENE;486
86.1;ABSTRACT;486
87;CHAPTER 82. STRUCTURE OF LINEAR LOW POLYMERS OF ACETYLENE;489
87.1;ABSTRACT;489

Leseproben

2

A NEW CLASS OF POLYMERS OF a-OLEFINS WITH AN EXCEPTIONAL REGULARITY OF STRUCTURE*

G. NATTA

(11 Dec. 1954) [ (8) 4, 61 (1955)] [ 16, 143 (1955)]

SUMMARY

The exceptional properties of a new class of macromolecular hydrocarbons having a linear structure, obtained by polymerization of a-olefins, are described in this paper.The high melting temperature, the high crystallinity, the slight solubility, and the peculiar mechanical properties of these polymers are attributed to a particular regularity of structure due to the existence, in each macromolecule, of long and ordered sequences of asymmetric carbon atoms having the same steric configuration.A suggestion is made to call “isotactic” this particular type of arrangement of the asymmetric carbon atoms of the linear macromolecules.

Vinyl polymers, obtained by head-to-tail polymerization of monomers of the CH2 = CHR type, possess main chains in which asymmetric carbon atoms are alternated with methylenic groups.

The inability of polymers containing successions of —CH2—CHR—groups to crystallize whenever the R group is larger than the hydrogen atom bound to the tertiary carbon atom, was attributed to the different configuration of the asymmetric carbon atoms. This seems to be the reason why in the chain of these polymers, no regular repetition of constitutive elements identical as far as the space is concerned can exist; whereas, there is a succession, normally statistically disordered, of two different structural units, which differ from one another only in their steric configurations of the relating asymmetric carbon atoms.

All the polymers derived from the olefins of the aforesaid type, in which R is an alkyl group, are liquid or amorphous solids.

The presence of methyl side groups (with an actual van der Waals’ radius of about 2 Å) or of other groups of even larger size was moreover considered, in this type of polymers, as a certain hindrance to the formation of fully planar zigzag chains of paraffins stretched on a plane.

According to Flory,1 a better condition to obtain a chain with a regular planar structure would entitle the alternate succession, along the chain, of asymmetric carbon atoms with opposite steric configurations. A similar structure had been proposed for crystalline polyvinylisobutyl ethers, prepared by C. E. Schildknecht, S. T. Gross, H. R. Davidson, I. M. Lambert, A. O. Zoss2 operating at very low temperatures with an extremely slow polymerization rate.

Steric hindrances decrease only if the R groups possess (as F, OH) a radius smaller than 1·4 Å, that is, if their size is not considerably larger than that of the hydrogen atom bound to the carbon atom; in that case, the formation of the rigid zigzag planar chain, which is typical of the rhombic structure of paraffins, is still possible.

Therefore, we were extremely surprised, toward the beginning of March 1954, when we discovered that the fractionation of solid high-molecular-weight polymers of propylene, which we prepared by adopting procedures and conditions suitable for obtaining polymers with essentially linear chains (that is without branchings longer than those in the R group), gave a considerable portion of crystalline polymers, as revealed by X-ray examination.

Later on, we prepared crystalline polymers of other aliphatic a-olefins and of styrene, and we probed into their structures, in order to understand the essence of these new products.

In another communication we will report the general methods that allowed us to obtain remarkable amounts of these crystalline polymers, or to produce at will amorphous non-crystallizable polymers. This topic is still under investigation.

We only refer here to the methods used by us for separating crystalline polymers, to their peculiar properties and the relationship between such properties and the structure of the chains.

SEPARATION OF THE CRYSTALLINE POLYMERS FROM THE AMORPHOUS ONES AND THEIR PROPERTIES

Fractionation of some crude polymers of propylene, carried out by extraction with solvents, done in March 1954, yielded a series of fractions whose properties did not appear to have a regular function with respect to the molecular weight. For instance, ether-soluble fractions of molecular weight higher than 40,000 were highly crystalline up to at least 130°C, whereas acetone-insoluble fractions but ether-soluble, of molecular weight lower than 35,000 were completely amorphous even at low temperature. Intermediate fractions did not appear to have a polymeric composition with intermediate properties, but rather to exist as a heterogeneous mixture of two parts: one crystalline and one amorphous.

Having observed this phenomenon, we studied how these anomalies had occurred, and why they did not occur when the polymers obtained were fractionated by adopting the polymerization conditions normally used.

Therefore, we performed subsequent extraction runs of the crude polymers with a series of solvents with a solvent power, at their boiling temperature, in the increasing order: acetone, ethyl acetate, ether, n-heptane, benzene, toluene.

With regard to polypropylene, the ether extract is completely amorphous, while the n-heptane insoluble product is completely crystalline. With regard to poly-a-butylene, a separation of the two types of products may be performed with boiling ether. Crystalline polystyrene may be easily separated from the amorphous one due to its insolubility in boiling n-heptane.

Some characteristic properties common to polypropylene, polybutenes, polystyrenes, concerned with both types of polymers separated by us in the way described above, are compared in Table 1.

TABLE 1

Appearance

Elastic at a temperature above that of the 2nd order transition, vitreous at a lower temperature

Can be pressed at temperatures near to the temperature of the 1st order transition to tough and flexible lamina

X-ray examination

Typical bands of the prevailingly amorphous linear polymers

Crystallinity up to 120 °C at least

Polarized-light I.R. spectra

Absence of dichroism

Strong dichroism

Thermal analysis

Melting or softening at temperatures below 110°C

Temperature of the 1st order transition > 120°C

Density

Low

High

Behaviour with regard to the mechanical deformations

Viscoelastic at temperatures higher than the temperature of the 2nd order transition

Orientation of the crystals and corresponding anisotropies

Tensile strength

Low

Very high in the oriented polymers

Even if the measurements of the intrinsic viscosity (performed on about one hundred samples) had generally given higher values for the crystalline polymers than for the amorphous ones (which had been separated from the same crude product), this, notwithstanding the difference of properties of the two types of products, would not have been attributed to the difference of molecular weights.

In fact, we could separate fractions, some crystalline, others amorphous, that in solution have the same intrinsic viscosity, and very likely similar molecular weights. As we shall see later these are polymers that in both cases are essentially linear.

Furthermore, crystalline products have been obtained by thermal depolymerization of highly crystalline polypropylenes, having an average molecular weight of about 100,000; and this also occurred when the molecular weight decreased to values (3000–5000) much lower than those of a great number of completely amorphous polypropylenes, which have molecular weights higher than 20,000.

The properties of some fractions of the two types of polypropylenes and of polybutenes are compared in Table 2. Intrinsic viscosities were determined in tetralin, at 135°C. The indicated transition temperature represents the temperature at which the X-ray diffraction bands, typical of the crystalline phase, disappear completely. Solubilities in various solvents are indicated at their boiling temperature (i., insoluble, s., soluble, v.s., very soluble).

TABLE 2

Even more marked differences have been observed when comparing crystalline and amorphous polystyrenes. A comparison is made herein between commercial amorphous polystyrenes and a polystyrene having the following properties: it is insoluble in acetone, ether, n-heptane, but soluble in toluene; it has an intrinsic viscosity at 25°C: [?] = 3·8 × 102 cm3/g (determined in benzene solutions); it remains crystalline up to above 200°C, and has a temperature of the first order transition of 213°C, as determined by dilatometric means:

The remarkable differences existing between the physical properties of the two types of polymers must be attributed to a common reason, which must be looked for in the...