Viscosity measurement

• US 6,945,094 B2
• Filed: 12/21/2001
• Issued: 09/20/2005
• Est. Priority Date: 12/22/2000
• Status: Expired due to Fees

• Current Assignee: Borealis Technology Oy (IPIC Holdings GmbH)
• Original Assignee: Borealis Technology Oy (IPIC Holdings GmbH)
• Inventors: Halstensen, Mats, Esbensen, Kim, Eggen, Svein
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Hanley, John C
• Application Number:
  US10/451,226
• Publication Number:
  US 20040060345A1
• Time in Patent Office: 1,369 Days
• Field of Search: 73/540.1, 73/542.4, 73/544.1, 735/87
• US Class Current: 73/54.41
• CPC Class Codes: G01N 11/08 by measuring pressure required to produce a known flow
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level
• CPC Class Codes: G01N 29/032 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/222 Constructional or flow details for analysing fluids optoacoustic fluid cells G01N29/2425
• CPC Class Codes: G01N 29/30 Arrangements for calibrating or comparing, e.g. with standard objects
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14

Abstract

The present invention relates to a method and apparatus of determining the rheological properties of a polymer flowing in a conduit. The invention provides a method of characterising a polymer under test, comprising: Detecting acoustic emissions from said polymer flowing in a conduit to provide acoustic emission data, comparing the acoustic emissions data obtained against acoustic emission data from a polymer, or a series of polymers, of known characteristics, and thereby characterising the polymer.

Claims

1. A method of characterising a polymer under test, comprising:

flowing said polymer through a conduit in a controlled manner such that said polymer experiences a predetermined flow rate,

detecting acoustic emissions from said polymer flowing in the conduit to provide acoustic emission data relating solely to said polymer, and

comparing the acoustic emissions data obtained against acoustic emission data from a polymer, or a series of polymers, of known characteristics, and-thereby characterising the polymer.

2. A method as claimed in claim 1 wherein a rheological property of the polymer under test is thereby determined.

3. A method as claimed in claim 1 wherein the identity of the polymer under test is thereby determined.

4. A method as claimed in claim 2 wherein the rheological property under test is the viscosity of the polymer.

5. A method as claimed in claim 1 wherein the acoustic emissions are detected by means of an accelerometer.

6. A method as claimed in claim 1 wherein said conduit is associated with a pipe leading directly from a polymerisation reactor.

7. A method as claimed in claim 1 wherein said conduit is associated with an extruder.

8. A method as claimed in claim 1 wherein said conduit comprises a structural detail altering flow characteristics of the polymer flowing in the conduit.

9. A method as claimed in claim 1 wherein the acoustic emissions data is analysed using Principal Component Analysis (PCA) techniques.

10. An apparatus for characterising a molten polymer, comprising:

a) means for controlling the flow of said polymer through a conduit such that the polymer experiences a predetermined flow rate;

b) an acoustic sensor capable of detecting acoustic emissions from the polymer and thereby generating a signal relating solely to acoustic emissions data from said polymer; and

c) means for comparing the signal against acoustic emissions data from molten polymers of known characteristics.

11. An apparatus as claimed in claim 10, wherein said apparatus is adapted whereby to determine a value for a desired rheological property of the polymer under test.

12. An apparatus as claimed in claim 10, wherein said apparatus further comprises means for identifying the polymer.