Origin of double melting peaks of α-form isotactic polypropylene: Recrystallization and lamellar thickness hierarchy

2010 ◽  
pp. n/a-n/a
Author(s):  
Jinhai Yang
Keyword(s):  
Isotactic Polypropylene ◽  
Lamellar Thickness

Kinetics of non-isothermal melting and crystallization of gamma-irradiated isotactic polypropylene

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Emanuel Nedkov ◽  
Tatyana Dobreva
Keyword(s):  
Constant Temperature ◽  
Isotactic Polypropylene ◽  
Crystallization Rate ◽  
Melting Rate ◽  
Isothermal Kinetics ◽  
Lamellar Thickness ◽  
Scanning Calorimetry ◽  
Gamma Irradiated ◽  
Kinetics Of ◽  
Melting And Crystallization

Abstract The non-isothermal kinetics of melting and crystallization of gamma-irradiated isotactic polypropylene were investigated by differential scanning calorimetry. At constant temperature the melting rate increased with the dose. During the melting, the average lamellar thickness, the free surface energy and the transport energy through the phase boundary reduced with increasing the dose. The crystallization rate decreased with increasing dose at constant temperature. Mixed α-γ spherulites were grown during crystallization. The non-isothermal crystallization rate expressed, in fact, the rate of secondary nucleation of the lamellae in the spherulites and their growth. Raising the irradiation doses led to a decrease of the crystallization temperature. A critical dose of irradiation of about 200 kGy was found, where the dependences of the calculated kinetic parameters underwent an important change. This change could be successfully connected with the effect of radiation annealing and melting.

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.

Mononuclear phenols substituted with tert-butyl, cyclohexyl or 1-phenylethyl groups as antioxidants in isotactic polypropylene

1978 ◽  
Vol 43 (10) ◽  
pp. 2578-2582 ◽  
Author(s):  
Jan Holčík ◽  
Pavel Čaučík ◽  
Jan Pospíšil
Keyword(s):  
Isotactic Polypropylene ◽  
Tert Butyl

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 Unique Slow Crack Growth Behavior of Isotactic Polypropylene: The Role of Shear Layer-Spherulites Layer Alternated Structure

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2746
Author(s):  
Mingjin Liu ◽  
Jiaxu Luo ◽  
Jin Chen ◽  
Xueqin Gao ◽  
Qiang Fu ◽  
...  
Keyword(s):  
Shear Layer ◽  
Crack Growth ◽  
Isotactic Polypropylene ◽  
Slow Crack Growth ◽  
Crack Growth Behavior ◽  
Polymer Science ◽  
The Past ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

With the development of polymer science, more attention is being paid to the longevity of polymer products. Slow crack growth (SCG), one of the most important factors that reveal the service life of the products, has been investigated widely in the past decades. Here, we manufactured an isotactic polypropylene (iPP) sample with a novel shear layer–spherulites layer alternated structure using multiflow vibration injection molding (MFVIM). However, the effect of the alternated structure on the SCG behavior has never been reported before. Surprisingly, the results showed that the resistivity of polymer to SCG can be enhanced remarkably due to the special alternated structure. Moreover, this sample shows unique slow crack propagation behavior in contrast to the sample with the same thickness of shear layer, presenting multiple microcracks in the spherulites layer, which can explain the reason of the resistivity improvement of polymer to SCG.

Mesoporous films based on isotactic polypropylene deformed via the mechanism of crazing

2021 ◽  
Vol 70 (1) ◽  
pp. 62-66
Author(s):  
L. M. Yarysheva ◽  
A. Yu. Yarysheva ◽  
O. V. Arzhakova ◽  
A. L. Volynskii
Keyword(s):  
Isotactic Polypropylene ◽  
Mesoporous Films

Kinetics of microstructure rearrangement during annealing of cold-drawn isotactic polypropylene

1982 ◽  
Vol 20 (3) ◽  
pp. 497-508 ◽  
Author(s):  
Suzanne Babajko ◽  
J. M. Schultz
Keyword(s):  
Isotactic Polypropylene ◽  
Kinetics Of
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