scholarly journals Molecular Weight Effect on the High Pressure Crystallization of Polyethylene

1988 ◽  
Vol 20 (12) ◽  
pp. 1075-1082 ◽  
Author(s):  
Munehisa Yasuniwa ◽  
Shinsuke Tsubakihara ◽  
Chitoshi Nakafuku
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Weight Effect ◽  
Pressure Crystallization

The High Pressure Rheology of Mixtures

2004 ◽  
Vol 126 (4) ◽  
pp. 697-702 ◽  
Author(s):  
Scott Bair
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Binary Systems ◽  
Viscosity Coefficient ◽  
Shear Thinning ◽  
Newtonian Viscosity ◽  
Double Shear ◽  
Ideal Mixing ◽  
Viscosity Behavior ◽  
Single Flow

The Newtonian mixing rules for several binary systems have been experimentally investigated. Some systems show non-ideal mixing response and for some systems the non-ideal response is pressure-dependent, yielding an opportunity for manipulation of the pressure-viscosity behavior to advantage. The mixing of differing molecular weight “straight cuts” can produce very different pressure-viscosity response. This behavior underscores the difficulty in predicting the pressure-viscosity coefficient based upon chemical structure and ambient viscosity since the molecular weight distribution is also important, but it also provides another opportunity to control the high-pressure response by blending. The first experimental observation of double shear-thinning within a single flow curve is reported. Blending then provides the capability of adjusting not only the Newtonian viscosity but also the non-Newtonian shear-thinning response as well.

The Use of Novel F-RAFT Agents in High Temperature and High Pressure Ethene Polymerization: Can Control be Achieved?

2007 ◽  
Vol 60 (10) ◽  
pp. 788 ◽  
Author(s):  
Markus Busch ◽  
Marion Roth ◽  
Martina H. Stenzel ◽  
Thomas P. Davis ◽  
Christopher Barner-Kowollik
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
High Temperature ◽  
Degree Of Polymerization ◽  
Molecular Weight Distributions ◽  
High Pressure High Temperature ◽  
Reversible Addition ◽  
Weight Distributions ◽  
Raft Agent ◽  
Initial Results

Simulations are employed to establish the feasibility of achieving controlled/living ethene polymerizations. Such simulations indicate that reversible addition–fragmentation chain transfer (RAFT) agents carrying a fluorine Z group may be suitable to establish control in high-pressure high-temperature ethene polymerizations. Based on these simulations, specific fluorine (F-RAFT) agents have been designed and tested. The initial results are promising and indicate that it may indeed be possible to achieve molecular weight distributions with a polydispersity being significantly lower than that observed in the conventional free radical process. In our initial trials presented here (using the F-RAFT agent isopropylfluorodithioformate), a correlation between the degree of polymerization and conversion can indeed be observed. Both the lowered polydispersity and the linear correlation between molecular weight and conversion indicate that control may in principle be possible.

scholarly journals Preparation of silymarin nanocrystals using a novel high pressure crystallization technique and evaluation of its dissolution and absorption properties

2016 ◽  
Vol 11 (1) ◽  
pp. 211-212 ◽  
Author(s):  
Risako Onodera ◽  
Tomohiro Hayashi ◽  
Tatsuo Nakamura ◽  
Kaori Aibe ◽  
Kohei Tahara ◽  
...  
Keyword(s):  
High Pressure ◽  
Absorption Properties ◽  
Pressure Crystallization

Molecular weight effect on the obtainment of parallel and perpendicular orientation in thermotropic poly(diethylene glycol p,p′-bibenzoate)

2007 ◽  
Vol 60 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Vanesa Rodríguez-Amor ◽  
Juan P. Fernández-Blázquez ◽  
Antonio Bello ◽  
Ernesto Pérez ◽  
María L. Cerrada
Keyword(s):  
Molecular Weight ◽  
Diethylene Glycol ◽  
Perpendicular Orientation ◽  
Weight Effect
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