Polyolefins—The History and Economic Impact

Hutley, Trevor J.; Ouederni, Mabrouk

doi:10.1007/978-3-319-25982-6_2

Cited by 42 publications

(40 citation statements)

References 10 publications

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“…More than 300 grades of commercially available polyolefins provide a wide range of mechanical properties [ 1 ]. With more than 178 million tons having been produced in 2015 [ 2 , 3 ], polyolefins remain at the top of the global production of synthetic polymers [ 4 ]. From the point of view of cost, PE and i -PP rank as the least expensive polymers to produce, and stand out because they are far less toxic compared to many other commodity plastics [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Polyolefins, a Success Story

2017

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This paper reports the principal discoveries which have played a major role in the polyolefin field and have positioned polyolefins as the most produced plastics. The early development of polyolefins covering the production of LDPE (Low density polyethylene) at ICI (Imperial Chemical Industries) and the discovery of Phillips or Ziegler-Natta catalysts are highlighted in the first section. In the second part, the impact of the implementation of molecular catalysts on the research in polyolefins is discussed together with the most recent advances leading to high-performance tailor-made resins.

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Section: Introductionmentioning

confidence: 99%

Polyolefins, a Success Story

2017

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“…Polyolefins (POs) are ubiquitous materials in the modern economy, combining unrivalled functional properties with low cost, low weight and excellent barrier properties. In this market the Phillips catalyst produces hundreds of specialized PE grades, supplying almost 50% of the HDPE total world demand [1][2][3]. Since its discovery in 1951 [4], the Cr/SiO 2 Phillips catalyst was modified and evolved mainly following trial and error approaches or serendipitous discoveries.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Al-Alkyls on the Phillips Catalyst for Ethylene Polymerization: The Case of Diethylaluminum Ethoxide (DEALE)

et al. 2018

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Al-alkyls are often used in the industrial practice for modifying the Phillips catalysts for polyethylene production: they are not necessary to develop the activity, but they have relevant effects on the catalysis, decreasing the induction time, promoting the in situ branching, and enhancing the H 2 sensitivity for the molecular weight regulation. Herein we investigate the effect of diethylaluminum ethoxide (DEALE) on Cr(II)/SiO 2 (in a stoichiometric amount of Al:Cr=2:1), focusing the attention on the modification of the Cr(II) sites at a molecular level. Diffuse reflectance UV-Vis and FT-IR spectroscopies, applied in the presence of CO and CD 3 CN as molecular probes, unequivocally demonstrate that: 1) DEALE modifies only a fraction of the Cr(II) sites (ca. 30%) even if dosed in excess with respect to the Cr sites; 2) DEALE reacts with the silica surface, forming Al-grafted species which are at least partially in interaction with the Cr(II) sites and hence act as ancillary ligands; 3) the modified Cr(II) sites are more acidic and likely mono-grafted to the silica surface; the presence of Al-grafted species nearby is essential for their stabilization. Finally, kinetic experiments indicate that the modified Cr(II) sites are ca. 15 times faster in inserting ethylene than the unmodified Cr(II) sites. The intrinsic higher activity of the modified Cr(II) sites is a consequence not only of their molecular structure, but of the whole series of effects listed above.

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“…They are hydrocarbon molecules with at least one double carbon-carbon bond. Polyolefins are polymer molecules made using either free-radical, ionic initiators, inorganic (metal oxide) or organic-metallic catalysts (19). Each polymerization process produces a different Polyolefin type, being the linear high-molecular-weight thermoplastic polymers the ones mainly produced.…”

Section: State Of the Artmentioning

confidence: 99%

Synthetic waterproofing membranes and auxiliary separating layers in the inverted flat roof. Pressure effect on the degradation

Pedrosa

Rı́o

2018

Mater. construcc.

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Flat roofs are inverted when the insulation material is placed over the waterproofing membrane. This widely-used constructive system sets materials which may interact easily with each other causing their deterioration. The incompatibilities and the materials that may interact with each other are not completely described, the elements currently used to separate the materials are not totally efficient to avoid deterioration. This paper intends to enlarge the knowledge regarding the materials that are incompatible for inverted flat roofs, the conditions were interactions take place and the efficiency of some alternative solutions to separate the materials. The ethylene propylene diene monomer (EPDM) waterproofing membranes are incompatible with the extruded polystyrene (XPS). The interactions between incompatible materials increase with the pressure.

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Polyolefins—The History and Economic Impact

Cited by 42 publications

References 10 publications

Polyolefins, a Success Story

Polyolefins, a Success Story

The Effect of Al-Alkyls on the Phillips Catalyst for Ethylene Polymerization: The Case of Diethylaluminum Ethoxide (DEALE)

Synthetic waterproofing membranes and auxiliary separating layers in the inverted flat roof. Pressure effect on the degradation

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