Copolymerization of propylene with styrene and ethylene by a THF-containing half-sandwich scandium catalyst: efficient synthesis of polyolefins with a controllable styrene content

2017 ◽  
Vol 8 (3) ◽  
pp. 615-623 ◽  
Author(s):  
Rui Tan ◽  
Fang Guo ◽  
Yang Li
Keyword(s):  
Composition Range ◽  
Efficient Synthesis ◽  
Styrene Copolymers ◽  
Styrene Content ◽  
Half Sandwich

A novel family of multi-block propylene–styrene copolymers with syndiotactic styrene–styrene blocks and random propylene–ethylene–styrene terpolymers with a broad composition range were obtained by using (C5Me4SiMe3)Sc(CH2SiMe3)2(THF).

Ethylene—Styrene Copolymerization

1999 ◽  
Vol 72 (3) ◽  
pp. 553-558 ◽  
Author(s):  
Claudio Pellecchia ◽  
Leone Oliva
Keyword(s):  
Random Copolymer ◽  
New Materials ◽  
Polymerization Catalysts ◽  
Reaction Conditions ◽  
Proper Selection ◽  
Styrene Copolymers ◽  
Structures And Properties ◽  
Styrene Content ◽  
Poly Ethylene ◽  
Selection Of

Abstract Ethylene—styrene copolymers are new materials developed within the last decade using the new homogeneous olefin polymerization catalysts (generally referred to as “metallocene catalysts”). By proper selection of the catalytic system and the reaction conditions, a variety of copolymers with different compositions, structures, and properties can be obtained. Thus, copolymers containing a very low amount of styrene (or p-methylstyrene) on a substantially polyethylenic backbone are crystalline thermoplastics, which could be used to produce functionalized PEs. Increasing the styrene content leads to a rapid decrease in the crystallinity, affording materials which show good thermoelastomeric properties. Copolymers containing around 20 mol % styrene are effective compatibilizers for polyethylene—polystyrene blends. The molecular structure of these copolymers has been defined being “pseudorandom,” since EEE, EES, ESE, and SES sequences are observed, and no SS sequences are present, thus the styrene content cannot exceed 50 mol %. Very recently, however, a random copolymer containing SS sequences in a stereoregular arrangement has been reported. Also, truly alternating E-S copolymers have been obtained with suitable catalysts. These poly(ethylene-alt-styrenes) can be either atactic (and thus amorphous) or stereoregular, depending on the particular catalyst used. Interestingly, isotactic poly(ethylene-alt-styrene) is a new crystalline material with a melting point of 145 °C, whose crystal structure has recently been determined. In conclusion, further research on ethylene—styrene copolymerization promises to afford a variety of new interesting materials starting from two widespread, easily available and inexpensive monomers.

Styrene-Diene Resins in Rubber Compounding

1947 ◽  
Vol 20 (1) ◽  
pp. 241-248
Author(s):  
A. M. Borders ◽  
R. D. Juve ◽  
L. D. Hess
Keyword(s):  
Tensile Elongation ◽  
Chemical Properties ◽  
Aryl Hydrocarbon ◽  
Styrene Copolymers ◽  
Synthetic Rubber ◽  
Brittle Point ◽  
Styrene Content ◽  
Physical And Chemical ◽  
Preparation And Evaluation ◽  
Butadiene Styrene

Abstract Early in the investigation of butadiene-styrene copolymers as synthetic rubbers, this laboratory became interested in copolymers containing much more styrene than any of the American or German synthetics. This interest was soon directed to the resinous copolymers obtained when the styrene content is increased beyond the range in which rubberlike properties are observed at room temperature. The exploratory work, therefore, involved preparation and evaluation of butadiene-styrene copolymers containing from 65 to 98 per cent styrene. No description of similar polymers has been found. Konrad and Ludwig claimed the improvement of rubberlike properties of butadiene-styrene copolymers by increasing the styrene content from the normal range to “between about 47.5 and about 70 per cent”. The claims and examples of this patent emphasize the improvement of rubberlike properties, such as tensile, elongation, and rebound, at high temperatures. It is well known in this country, however, that increase in styrene content beyond a certain point, perhaps 50–55 per cent, is accompanied by a loss of overall balance of rubber characteristics. Therefore, the copolymers at the upper end of the range described by Konrad and Ludwig have definite limitations for rubber uses—for example, low rebound, high brittle point, shortness, etc. In the writers' laboratory useful resins have been prepared from dienes and vinyl aryl hydrocarbons in the range 5 to 20 per cent diene and 80 to 95 per cent vinyl aryl hydrocarbon. This paper describes the properties and certain uses of one of these copolymers containing approximately 15 parts of butadiene and 85 parts of styrene. This material possesses a combination of physical and chemical properties which permit its use in several applications where cyclized natural or synthetic rubbers are commonly employed. Cyclized natural rubber has been described by Bruson, Endres, and Thies and Clifford. Cyclized synthetic rubbers were described recently by Endres. One product of this type is made from a special synthetic rubber. The new 15 butadiene—85 styrene copolymer is now identified as Pliolite S-3, since it may be used in many Pliolite applications, often with distinct advantages over either the natural or synthetic rubber derivatives.

Crystallization in Butadiene-Styrene Copolymers

1955 ◽  
Vol 28 (1) ◽  
pp. 51-56
Author(s):  
Lawrence A. Wood
Keyword(s):  
Experimental Observation ◽  
Polymerization Temperature ◽  
Styrene Copolymers ◽  
Styrene Content ◽  
Butadiene Styrene

Abstract From Figure 3 one draws the following significant conclusions: (1) Crystallization is not observed if the polymerization temperature is above 60° C. (2) For polymerization at 50° C, a small amount (2 to 6 per cent) of bound styrene inhibits crystallization completely. (3) For polymerizations at 5° C, the limit is at about 15 to 18 per cent bound styrene content. (4) At the lowest polymerization temperatures normally utilized, this limit is at about 30 per cent bound styrene. Direct experimental observation is in general accord with these conclusions.

Half-sandwich rare-earth metal tris(alkyl) ate complexes catalyzed phosphaguanylation reaction of phosphines with carbodiimides: an efficient synthesis of phosphaguanidines

2015 ◽  
Vol 39 (10) ◽  
pp. 7649-7655 ◽  
Author(s):  
Wangyang Ma ◽  
Ling Xu ◽  
Wen-Xiong Zhang ◽  
Zhenfeng Xi
Keyword(s):  
Catalytic Activity ◽  
Rare Earth ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Efficient Synthesis ◽  
Yttrium Complexes ◽  
Half Sandwich

Half-sandwich Y/Li ate complex displays better catalytic activity for phosphaguanylation reaction of phosphines with carbodiimides than the neutral yttrium complexes.

Sign in / Sign up

Export Citation Format

Share Document