The influence of regio- and stereoirregularities on the crystallization behaviour of isotactic poly(propylene)s prepared with homogeneous group IVa metallocene/methylaluminoxane Ziegler-Natta catalysts

1994 ◽  
Vol 195 (4) ◽  
pp. 1433-1441 ◽  
Author(s):  
David Fischer ◽  
Rolf Mülhaupt
Keyword(s):  
Homogeneous Group ◽  
Crystallization Behaviour ◽  
Group Iva ◽  
Poly Propylene ◽  
Ziegler Natta Catalysts

Solid-State NMR Characterization of the Chemical Defects and Physical Disorders in α Form of Isotactic Poly(propylene) Synthesized by Ziegler–Natta Catalysts

2013 ◽  
Vol 46 (16) ◽  
pp. 6507-6519 ◽  
Author(s):  
Zhen Li ◽  
Toshikazu Miyoshi ◽  
Mani K. Sen ◽  
Tadanori Koga ◽  
Akihiro Otsubo ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Nmr Characterization ◽  
Physical Disorders ◽  
Poly Propylene ◽  
Ziegler Natta Catalysts

Molecular dynamics of poly(propylene) glycol in nanometer confinements

2000 ◽  
Vol 10 (PR7) ◽  
pp. Pr7-271-Pr7-274 ◽  
Author(s):  
A. Schönhals ◽  
H. Goering ◽  
K.-W. Brzezinka ◽  
Ch. Schick
Keyword(s):  
Molecular Dynamics ◽  
Propylene Glycol ◽  
Poly Propylene

Crystallization of Isotactic Poly(propylene) in Solution as Followed by Slow Calorimetry

1995 ◽  
Vol 60 (11) ◽  
pp. 1905-1924 ◽  
Author(s):  
Hong Phuong-Nguyen ◽  
Geneviève Delmas
Keyword(s):  
Molecular Weight ◽  
Crystal Growth ◽  
High Temperature ◽  
Heat Of Fusion ◽  
Complete Dissolution ◽  
Polymer Molecular Weight ◽  
Solvent Quality ◽  
Temperature Ramp ◽  
Poly Propylene

Dissolution, crystallization and second dissolution traces of isotactic poly(propylene) have been obtained in a slow temperature ramp (3 K h-1) with the C80 Setaram calorimeter. Traces of phase-change, in presence of solvent, are comparable to traces without solvent. The change of enthalpy on heating or cooling, ∆Htotal, over the 40-170 °C temperature range, is the sum of two contributions, ∆HDSC and ∆Hnetwork. The change ∆HDSC is the usual heat obtained in a fast temperature ramp and ∆Hnetwork is associated with a physical network whose disordering is slow and subject to superheating due to strain. When dissolution is complete, ∆Htotal is equal to ∆H0, the heat of fusion of perfect crystals. The values of ∆Htota for nascent and recrystallized samples are compared. Dissolution is the tool to evaluate the quality of the crystals. The repartition of ∆Htotal, into the two endotherms, reflects the quality of crystals. The crystals grown more rapidly have a higher fraction of network crystals which are stable at high T in the solvents. A complete dissolution, i.e. a high temperature (170 °C or more) is necessary to obtain good crystals. The effect of concentration, polymer molecular weight and solvent quality on crystal growth is analyzed.

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