The viscosity of polymer melts is a key parameter for quality and control during every stage of the polymer manufacturing process, including injection molding, compression molding and extrusion. Molecular chain length (or molecular weight) is the most important indicator when measuring polymers across every stage. Chain length tells the operators how well the product has polymerized, which is critical for the properties of the finished product, which might be granules, film, fibers or molds. The strength, hardness and density are all key parameters for product quality, and can be controlled by viscosity.
In the textile industry viscosity is a key parameter in understanding how well the polymer can be forced through the fine holes of the spinneret, to produce the fibers. This enables extrusion of filaments of one denier or less. Tensile strength is a particularly important property to control for fiber. As a general rule, tensile strength increases as polymer viscosity increases.
To achieve their desired behavior, polymers are often blended to alter their properties. Properties such as solubility, water-repellence and flexibility can be altered by substituting other organic groups for the methyl groups. For example, silicones with phenyl groups are more flexible polymers than those with methyl groups. They are also better lubricants and are superior solvents for organic compounds. Picking up changes in viscosity and molecular weight is critical in order to control the addition and blending of co-polymers.
Why is the XL7-d16 good for polymers?
The XL7-d16 spike has been developed to be the ultimate tool for managing polymer melt, right where it’s needed most – in the pipe. The d16 spike has been completely redesigned to operate at a lower shear-rate than the standard XL7 viscometer, which results in an optimum response to changing molecular weight within the polymer.
The spike design also has no bob. This means the viscometer can easily be extracted without damage if the polymer hardens in the pipe. The flange includes two jacking bolt threaded holes, so the sensor can be extracted with ease. For further simplicity of use, the d16 has been designed to retro-fit existing polymer melt equipment without the need to change pipework.
The sensor also has all the attributes found in every Hydramotion viscometer: high accuracy, no moving parts, negligible maintenance, and a robust construction to withstand harsh duty and high pressure. The all-welded solid sensor rod also has an open construction to ensure no trap areas or dead-zones for polymer melt.
Further information and specification can be found on our XL7-d16 product page.
Any industry processing polymer melts. Typically the textile industry which turns PET into textile threads, “Lycra” has seen particularly successful results using d16.
The following melts are currently being measured:
- PBAT (polybutylene adipate terephthalate) – biodegradable polymer
- Polyamide (nylon 6,6)
- “Lyocell” cellulose – natural fiber used in clothing
- Lycra or “Spandex” (polyether-polyurea copolymer)
- Silicone-based polymers
We have inline viscometers for every stage of polymer processing and handling: material manufacture, melt pipe, or extruder. Please see our polymers industry page for more information.
We would be glad to answer any questions you may have about polymer melt-pipe viscometers or any of our other products.