Self‐welding 1‐butene/ethylene copolymers from metallocene catalysts: Structure, morphology, and mechanical properties

Abstract

Samples of random copolymers consisting of 1-butene modified with a low ethylene content (4, 5, 8% by weight) produced with metallocene catalysts were studied to elucidate the polymorphic behavior of this new class of materials and to characterize them from a structural, morphological, and mechanical point of view. The samples cooled down from the melt are in amorphous phase and crystallize in a mixture of form I and I 0 or in pure form I 0 with aging time, according to the C2 content. Infrared and nuclear magnetic resonance spectroscopy, X-ray diffraction and microscopic techniques were used to follow the changes of the material with aging time and to correlate the structural and morphological behavior with the peculiar mechanical properties that differentiate the samples with increasing C2 content. The presence, in the aged samples with higher C2 content, of the pure form I 0 induces the peculiar ability to self-welding and these copolymers combine high flexibility with good elasticity and ductility and can be processed directly or used as modifying agents in polymers.One of the approaches proposed for increasing the rate of form transformation II ! I is to use copolymers of 1-butene. When ethylene (C2) comonomeric units are inserted in the IPB chains, Additional Supporting Information may be found in the online version of this article.

Cross-Metathesis of Microbial Oils for the Production of Advanced Biofuels and Chemicals

“…This supports the inference that ruthenium hydride complexes, formed by the deactivation of the HGII, are acting as isomerization catalysts. These terminal alkenes, as well as the pentadiene isomers, are higher-value products, suitable as precursors in polypropylene, synthetic rubber, and alternative polymer processes. − These side products could potentially support fuel production, forming the basis for a renewable biorefinery from microbial oils.…”

“…Previously, research has been carried out on fatty acid alkyl ester (FAAE) model compounds (normally methyl oleate), allowing for easier analysis and preventing oligomer formation from oil self-metathesis. Because of the common distribution of the double bonds present in polyunsaturated fatty acid chains, metathesis of these oils leads to the formation of more complex products such as a range of volatile alkenes, such as 1-butene, 1,4-pentadiene, and 3-hexene. − These components have the potential to be useful precursors for higher-value products or as co-monomers for polymer production. − …”

Poly (1-butene-ran-ethylene) Monomodal Copolymers from Metallocene Catalysts: Structural and Morphological Differences with Increasing Ethylene Content

“…In particular, for the most modified copolymers, a peculiar characteristic was found, that is the ability to be undergo "self-sealing" after being cut. This effect has been attributed to the high mobility of the polymer chains due to the low melting temperature of form I’ and to the low degree of crystallinity of the copolymer [25].…”

“…The presence of ethylene, in addition to acting on the polymorphic behavior of the PB, involves some variations in the properties of the polymer such as the decrease of the crystallization rate, the degree of crystallinity and the melting temperature. Its influence on the mechanical properties of the copolymer is also noteworthy: the increase in the comonomer content follows the decrease in the glass transition temperature, the hardness and the breaking load while increasing flexibility and elasticity [23,25].…”

Direct Formation of Different Crystalline Forms in Butene-1/Ethylene Copolymer via Manipulating Melt Temperature

“…Form II crystallites can transform into the thermodynamically stable form I when held at room temperature. − This transformation process can be accelerated by stretching, and the reversible process was also observed upon stretching at the elevated temperature due to a stress-induced melting and recrystallization process . Form I′ crystals can be formed directly under peculiar conditions, like in ultrathin film, self-seeding, ,, high pressure, − and in polymers with different concentration of stereodefects or counits. − Form III and form I′ have been found to form in solution crystallization, depending on the solvent, concentration, and the crystallization temperature − which can be transformed into form II by stretching at higher temperature . Up to now, the exact mechanism of direct crystallization of form I′ from molten state of PB-1 and its copolymers remains elusive.…”