Dryflex WS H 2. O Hydrophilic Thermoplastic Elastomers

Transcription

1 Dryflex WS H 2 O Hydrophilic Thermoplastic Elastomers

2 CONTENTS INTRODUCTION HOW DOES IT WORK? HOW MUCH DOES IT SWELL & HOW QUICKLY? % VOLUME SWELL DOES IT RETURN TO ITS ORIGINAL SIZE WHEN THERE IS NO LONGER WATER PRESENT? TYPICAL APPLICATIONS GRADE TABLE PROCESSING CONTACT

3 INTRODUCTION With the Dryflex WS range we have turned the usual water-resistant properties of thermoplastic elastomers (TPE) on their head to create materials that swell up to ten times their volume when immersed in water. These materials have been developed to expand upon contact with aqueous solutions (ph7 to 12) to form a positive seal and prevent the ingress or exit of water. A range of formulations have been developed which offer different swell rates when immersed in water. When there is no longer water present the compound shrinks back to its original size, a process of expansion and contraction that can be repeated an unlimited number of times. The compounds have solid structural integrity; unlike many of the equivalent clay based products which can erode and shatter over time. Compounded in any colour, the water swellable TPE is 100% recyclable and can be processed using conventional fabricating methods, including extrusion and injection moulding. Antimicrobial versions are also available. Please use this guide as an introduction to our Dryflex WS range and contact us to discuss your specific requirements.

4 HOW DOES IT WORK? Fig 1 : The active hydrophilic ingredient is added to the Dryflex WS TPE compound at the time of manufacture Fig 2 : Upon contact with water, the Dryflex WS TPE compound will expand uniformly, at a controlled rate and percentage Fig 3 : When there is no longer water present the Dryflex WS TPE compound shrinks back to its original size

5 HOW MUCH DOES IT SWELL & HOW QUICKLY? We have developed a range of compounds that offer swell rates from 350% to 1000% when immersed in water. We can also customise the swell rate to meet the requirements of a specific application. The swell is not instant, it is seen over a period of hours and days. The swell rate is determined by: The hardness of the Dryflex WS compound The formulated level of swell Environmental conditions (for example temperature and water conditions) Profile geometry Surface finish

6 DRYFLEX WS % VOLUME SWELL % Volume Swell Dryflex WS 25E950 Dryflex WS 40E850 Dryflex WS 35E550 Dryflex WS 40E Time in Days

7 DOES IT RETURN TO ITS ORIGINAL SIZE WHEN THERE IS NO LONGER WATER PRESENT? Yes, in fact this is one of the strengths of Dryflex WS TPE compounds. Their structural integrity means they can withstand longterm cycling from wet to dry. Please contact us at to receive further data about the effects of temperature, water ph and water salinity on the swell rate. We can also provide data regarding the long-term cycling effects.

8 APPLICATIONS One of the main applications for Dryflex WS compounds are hydrophilic waterstops. These are typically used as part of a concrete structure and intended to prevent the passage of fluids (e.g. water) when embedded in and running continuously through concrete joints. We have developed softer grades which offer excellent drapability. They are an ideal choice for waterstops where the profiles may be coiled or need to be fitted around complex structures. Other applications for Dryflex WS TPEs include tunnels, water treatment plants, drains, sewers, tanks, glazing and cable protection.

9 TYPICAL DRYFLEX WS GRADES Material Hardness (1) Shore A Density g/cm 3 Water Swell Rate (2) % Comments Test Method ISO 868 ISO 2781 Dryflex WS 25E Suitable for injection moulding & extrusion Dryflex WS 25E Suitable for injection moulding & extrusion Dryflex WS 25E Suitable for injection moulding & extrusion Dryflex WS 40E Optimised for extrusion Dryflex WS 40E Optimised for extrusion Dryflex WS 40E Optimised for extrusion (1) After 15 seconds (2) Minimum swell rate, up to 21 days immersion period in de-ionised water at 23 C

10 PROCESSING Dryflex WS TPE compounds are primarily designed for extrusion processing techniques, but may also be thermoformed by injection moulding. Due to the nature of the swelling process, many factors can affect the overall level of swell and the rate at which swelling occurs; During processing, orientation effects and built-in stresses can have a major impact on performance Extrusion temperatures at the die should not be too low and extrudate not force cooled in order to allow for a relaxed and random formation of the polymer structure Profile geometry may also affect the degree of swell During injection moulding, the differences are more dramatic when dealing with higher levels of orientation and thinner products, these cool quicker resulting in vastly reduced and slower swell rates Product design and gate placement are contributing factors to the swell characteristics We suggest that in order to maximize swelling, warmer tools are used and if possible, products are demoulded as warm as possible Once a product has been formed, there are further factors which can have a bearing on the performance of the material, these include: preconditioning, temperature, volume and ph of the water which is in contact with the article

11 PROCESSING : EXTRUSION L/D Ratio: 20:1-25:1 Compression Ratio: Breaker Plate/Screen: Both should be used Draw Down: 5-10% Cooling: Air cool only (must not come into contact with water) Temperatures C Shore A Shore A

12 PROCESSING : INJECTION MOULDING Injection Speed: Injection Pressure: Back Pressure: Holding Pressure: Cooling: Medium - Fast Medium - Fast Low - Medium Sufficient to pack the mould Can be demoulded when parts have cooled sufficiently Temperatures C

13 WANT TO LEARN MORE? the Dryflex WS team at or visit Dryflex WS Timelapse Video

14 ABOUT HEXPOL TPE HEXPOL TPE is a global compounding group specialising in Thermoplastic Elastomers (TPE) for key industries such as consumer, medical, packaging, automotive and construction. We have a core belief in being the easiest company to do business with. That s why we invest in our operations, teams and technologies to offer our customers the most reliable, relevant and cost-effective TPE compounds, backed by highly responsive support, technical knowhow and application expertise. Our teams work together, across boundaries, applying the knowledge, experience and talents we have all around the world to meet the needs of our customers LEGACY NAMES: From 2017, the ELASTO and Müller Kunststoffe businesses were renamed to HEXPOL TPE. All the information about chemical and physical properties consists of values measured in tests on injection moulded test specimens. We provide written and illustrated advice in good faith. This should only be regarded as being advisory and does not absolve the customers from doing their own full-scale tests to determine the suitability of the material for the intended applications. You assume all risk and liability arising from your use of the information and/or use or handling of any product. Figures are indicative and can vary depending on the specific grade selected and the production site. HEXPOL TPE makes no representations, guarantees, or warranties of any kind with respect to the information contained in this document about its accuracy, suitability for particular applications, or the results obtained or obtainable using the information. Some of the information arises from laboratory work with small-scale equipment which may not provide a reliable indication of performance or properties obtained or obtainable on larger-scale equipment. We retain the right to make changes without prior notice. HEXPOL TPE makes no warranties or guarantees, express or implied, respecting suitability of either HEXPOL TPE s products or the information for your process or end-use application. Dryflex is a registered trademark, property of the HEXPOL TPE group of companies. EN_062017