Effect of high polymerization temperature on the microstructure of isotactic polypropylene prepared using heterogeneous ticl4/mgcl2 catalysts

2003 ◽  
Vol 90 (14) ◽  
pp. 3980-3986 ◽  
Author(s):  
Chifeng Zhong ◽  
Mingzhi Gao ◽  
Bingquan Mao
Keyword(s):  
Isotactic Polypropylene ◽  
Polymerization Temperature

scholarly journals Hafnium vs. Zirconium, the Perpetual Battle for Supremacy in Catalytic Olefin Polymerization: A Simple Matter of Electrophilicity?

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2621
Author(s):  
Antonio Vittoria ◽  
Georgy P. Goryunov ◽  
Vyatcheslav V. Izmer ◽  
Dmitry S. Kononovich ◽  
Oleg V. Samsonov ◽  
...  
Keyword(s):  
Isotactic Polypropylene ◽  
Strong Dependence ◽  
Quantitative Structure Activity Relationship ◽  
Activity Relationship ◽  
Polymerization Temperature ◽  
Quantitative Structure ◽  
Structure Activity ◽  
Qsar Models ◽  
Performance Decline ◽  
Increasing Temperature

The performance of C2-symmetric ansa-hafnocene catalysts for isotactic polypropylene typically deteriorates at increasing temperature much faster than that of their zirconium analogues. Herein, we analyze in detail a set of five Hf/Zr metallocene pairs—including some of the latest generation catalysts—at medium- to high-polymerization temperature. Quantitative structure–activity relationship (QSAR) models for stereoselectivity, the ratio allyl/vinyl chain ends, and 2,1/3,1 misinsertions in the polymer indicate a strong dependence of polymerization performance on electrophilicity of the catalyst, which is a function of the ligand framework and the metal center. Based on this insight, the stronger performance decline of hafnocenes is ascribed to electrophilicity-dependent stabilization effects.

Controlled grafting of poly(styrene-ran-n-butyl methacrylate) to isotactic polypropylene with nitroxidemediated polymerization

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Yusuke Sugino ◽  
Katsuhiro Yamamoto ◽  
Youhei Miwa ◽  
Masato Sakaguchi ◽  
Shigetaka Shimada
Keyword(s):  
Isotactic Polypropylene ◽  
Graft Polymerization ◽  
Reaction System ◽  
Gel Permeation Chromatography ◽  
Butyl Methacrylate ◽  
Molecular Characteristics ◽  
Polymerization Temperature ◽  
Local Concentration ◽  
Γ Irradiation ◽  
Polymerization Method

Abstract A nitroxide (2,2,6,6-tetramethylpiperidin-1-oxyl, TEMPO) mediated polymerization method was applied to the graft polymerization of styrene (ST)/ n-butyl methacrylate (BMA) to isotactic polypropylene (PP). PP peroxides produced by γ-irradiation in air were used as macroinitiator for grafting. The molecular characteristics of grafted and free poly(ST-r-BMA) chains were analysed by gel permeation chromatography, NMR and IR measurements. The molecular weight of grafted poly(ST-r-BMA) cleaved from PP was slightly higher than that of free poly(ST-r-BMA) generated simultaneously in the reaction system. Polydispersities of these polymers were narrow, indicating that grafting proceeded in a living fashion. The incorporated amount of BMA into grafted poly(ST-r-BMA) was smaller than that of free poly(ST-r-BMA). It is considered that the local concentration of BMA around propagating ends of graft poly(ST-r-BMA) was lower than that around free poly(ST-r-BMA) because PP cannot be dissolved in BMA monomer but in ST monomer at the polymerization temperature.

Properties of nanocomposites based on isotactic polypropylene and high-pressure polyethylene with metal-containing nanofillers

2020 ◽  
pp. 59-64
Author(s):  
N. I. Kurbanova ◽  
◽  
T. M. Gulieva ◽  
N. Ya. Ischenko ◽  
◽  
...  
Keyword(s):  
High Pressure ◽  
Synergistic Effect ◽  
Polymer Matrix ◽  
Isotactic Polypropylene ◽  
Rheological Parameters ◽  
Mechanochemical Method ◽  
X Ray ◽  
Effect Of Additives ◽  
High Pressure Polyethylene ◽  
Properties Of Composites

The effect of additives of nanofillers (NF) containing nanoparticles (NP) of copper oxide, stabilized by a polymer matrix of maleized polyethylene (MPE), obtained by the mechanochemical method, on the properties of composites based on isotactic polypropylene (PP) and high-pressure polyethylene (PE) was studied by X-ray phase (XRD) and thermogravimetric (TGA) analyzes. The enhancement of strength, deformation, and rheological parameters, as well as the thermo-oxidative stability of the obtained nanocomposites was revealed, which, apparently, is due to the synergistic effect of the interaction of copper-containing nanoparticles with anhydride groups of MPE. It is shown that nanocomposites based on PP/PE/NF can be processed both by pressing and injection molding and extrusion, which expands the scope of its application.

Effect of Polymerization Temperature on Polymerization Degree and Structure of Calcium Polyphosphate

2012 ◽  
Vol 27 (2) ◽  
pp. 174-178
Author(s):  
Hang WU ◽  
Li-Fang ZHANG ◽  
Wei BAI ◽  
Chi MA ◽  
Cheng-Dong XIONG
Keyword(s):  
Polymerization Temperature ◽  
Polymerization Degree ◽  
Calcium Polyphosphate

Cationic modifications of polyalkenes II. Effect of a single or continuous supply of Co-initiator

1989 ◽  
Vol 54 (5) ◽  
pp. 1269-1275
Author(s):  
Miloslav Kučera ◽  
Dušan Kimmer ◽  
Karla Majerová ◽  
Zdeněk Fiala
Keyword(s):  
Isotactic Polypropylene ◽  
Graft Copolymers ◽  
Single Addition

For an effective modification of polyalkenes leading to the formation of block and/or graft copolymers, the presence of co-initiating water is absolutely necessary. We have compared two procedures used in the co-initiation of cationic reactions on polymers. Gradually supplied air moisture raises the efficiency of modification of isotactic polypropylene with poly(oxyethylene) several times, compared with a single addition of co-initiating water.

Radiation Induced Graft Copolymerization of Vinyl Acetate and Isopropenyl Acetate Onto Isotactic Polypropylene

1996 ◽  
Vol 61 (2) ◽  
pp. 259-267 ◽  
Author(s):  
Bhupendra N. Misra ◽  
G. S. Chauhan ◽  
Inderjeet Kaur
Keyword(s):  
Vinyl Acetate ◽  
Isotactic Polypropylene ◽  
Graft Copolymerization ◽  
Optimum Conditions ◽  
Reaction Parameters ◽  
Maximum Percentage ◽  
Radiation Induced ◽  
Isopropenyl Acetate

Radiation-induced graft copolymerization of vinyl acetate (VAC) and isopropenyl acetate (PAC) onto isotactic polypropylene (IPP) has been studied. The percentage of grafting was calculated for various reaction parameters, and the optimum conditions for attaining the maximum percentage of grafting were determined. Maximal achieved extents of grafting are 39% and 29% for VAC and PAC, respectively. The reactivity of the two monomers with respect to grafting is discussed.

scholarly journals Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration

2019 ◽  
Vol 15 ◽  
pp. 963-970 ◽  
Author(s):  
Sora Park ◽  
Jeung Gon Kim
Keyword(s):  
Ball Milling ◽  
Mechanochemical Synthesis ◽  
Polymeric Materials ◽  
Solvent Free ◽  
Energy Output ◽  
Polymerization Temperature ◽  
Mechanical Degradation ◽  
Trimethylene Carbonate ◽  
Rate Acceleration ◽  
Conventional Solution

Mechanochemical polymerization is a rapidly growing area and a number of polymeric materials can now be obtained through green mechanochemical synthesis. In addition to the general merits of mechanochemistry, such as being solvent-free and resulting in high conversions, we herein explore rate acceleration under ball-milling conditions while the conventional solution-state synthesis suffer from low reactivity. The solvent-free mechanochemical polymerization of trimethylene carbonate using the organocatalysts 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) are examined herein. The polymerizations under ball-milling conditions exhibited significant rate enhancements compared to polymerizations in solution. A number of milling parameters were evaluated for the ball-milling polymerization. Temperature increases due to ball collisions and exothermic energy output did not affect the polymerization rate significantly and the initial mixing speed was important for chain-length control. Liquid-assisted grinding was applied for the synthesis of high molecular weight polymers, but it failed to protect the polymer chain from mechanical degradation.

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