- Library Home /
- Search Collections /
- Open Collections /
- Browse Collections /
- UBC Theses and Dissertations /
- The effect of boron nitride on the rheology and processability...
Open Collections
UBC Theses and Dissertations
UBC Theses and Dissertations
The effect of boron nitride on the rheology and processability of molten polymers Yip, Franky Kam Yin
Abstract
Experiments were carried out using capillary, sliding plate, and parallel plate rheometer and a blow moulding machine in order to assess the effect of boron nitride (BN) powders on the rheology and processability of a metallocene polyethylene, a Teflon FEP polymer and a polypropylene. In particular, to assess the processability of these resins in the presence of BN or not, the critical conditions for the onset of melt fracture is determined. The influence of the average size of boron nitride particles, its agglomeration if present, its concentration in the resins and the quality of the attained dispersion on the melt fracture of the metallocene polyethylene was particularly investigated. For this a number of boron nitride powders were examined having various characteristics, i.e. agglomeration, different particle size etc. It was found that for BN to be efficient in eliminating surface and gross melt fracture, the particle size should be about 10-20 microns in size, and free of agglomeration. Concentration was also found to be a critical factor, with the optimum value to fall in the range between 200 and lOOOppm. The mechanism by which BN acts to eliminate melt fracture was also investigated. Six different capillary dies with various entrance angles were used to study the entrance effect. A new apparatus was also designed during the course of this study in order to visualize the flow patterns developed at the entrance of the capillary. It was found that BN changes the entrance flow pattern of a PP by eliminating the onset of unstable flow. This is done by providing the condition for a smoother transfer of momentum from a polymer layer to the next. The effect of BN type on two blow molding grade high-density polyethylene was also studied by using a blow moulding machine. It was found that BN can eliminate the surface melt fracture of blow moulding grade HDPE depending on the properties of resins.
Item Metadata
Title |
The effect of boron nitride on the rheology and processability of molten polymers
|
Creator | |
Publisher |
University of British Columbia
|
Date Issued |
2000
|
Description |
Experiments were carried out using capillary, sliding plate, and parallel plate
rheometer and a blow moulding machine in order to assess the effect of boron nitride (BN)
powders on the rheology and processability of a metallocene polyethylene, a Teflon FEP
polymer and a polypropylene. In particular, to assess the processability of these resins in
the presence of BN or not, the critical conditions for the onset of melt fracture is
determined. The influence of the average size of boron nitride particles, its agglomeration
if present, its concentration in the resins and the quality of the attained dispersion on the
melt fracture of the metallocene polyethylene was particularly investigated. For this a
number of boron nitride powders were examined having various characteristics, i.e.
agglomeration, different particle size etc. It was found that for BN to be efficient in
eliminating surface and gross melt fracture, the particle size should be about 10-20 microns
in size, and free of agglomeration. Concentration was also found to be a critical factor,
with the optimum value to fall in the range between 200 and lOOOppm. The mechanism by
which BN acts to eliminate melt fracture was also investigated. Six different capillary dies
with various entrance angles were used to study the entrance effect. A new apparatus was
also designed during the course of this study in order to visualize the flow patterns
developed at the entrance of the capillary. It was found that BN changes the entrance flow
pattern of a PP by eliminating the onset of unstable flow. This is done by providing the
condition for a smoother transfer of momentum from a polymer layer to the next. The
effect of BN type on two blow molding grade high-density polyethylene was also studied
by using a blow moulding machine. It was found that BN can eliminate the surface melt
fracture of blow moulding grade HDPE depending on the properties of resins.
|
Extent |
16135570 bytes
|
Genre | |
Type | |
File Format |
application/pdf
|
Language |
eng
|
Date Available |
2009-07-09
|
Provider |
Vancouver : University of British Columbia Library
|
Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
|
DOI |
10.14288/1.0058633
|
URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
|
Graduation Date |
2000-05
|
Campus | |
Scholarly Level |
Graduate
|
Aggregated Source Repository |
DSpace
|
Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.