SPRINT™ ST 94
Knowde Enhanced TDS
Identification & Functionality+
Features & Benefits+
Applications & Uses+
- The moulding surface must first be treated with a release agent. If a Surface Film is required, this should be applied directly to the tool face prior to the lay-up of the SPRINT™. Please refer to Processing Notes for application details. The required number of plies of SPRINT™ are then placed on to the tool face. A thermocouple may be inserted into the lay-up outside the net trim line. It is important to provide air paths to each ply. This can be achieved by staggering the edges of the plies such that each subsequent ply is smaller by 5-10mm. If space is not available dry glass tows can be inserted between plies of SPRINT™ to provide an air evacuation path out of the laminate. The second end of the tow should be made available for contact with the breather
- If required, a peel ply, can be applied over the top of the laminate stack. Note that for good secondary bonding of a peel-plied surface of a laminate, a nylon peel ply such as Tygavac Stitch Ply A, is strongly recommended. The peel ply is covered entirely with a non-perforated release film such as Tygavac WL3600 or a low bleed release film, such as WL3600RP2. The release film is then covered with breather material, such as Tygavac Econoweave 44W, so that it extends over the release film in all directions and contacts the dry glass strands
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- Once the lay-up is complete, a vacuum bag is installed by standard techniques. At least two vacuum stems should be inserted through the bag, one connecting to the vacuum source and the other, at a point on the part furthest from the source, to a calibrated vacuum gauge. The major benefit of SPRINT™ is that it enables all of the air to be removed from the laminate prior to fibre wet out and resin cure. It is recommended that a vacuum is applied at ambient temperature prior to cure, to fully evaluate the laminate stack. This should be held for between 5 minutes and 1 hour, depending upon the size and thickness of the component. Full vacuum is then maintained throughout the cure.
- Cure the laminate in accordance with the specification given later in this datasheet.
Technical Details & Test Data+
- CURE ENVELOPE AND CURED PROPERTIES: ST 94 SPRINT™ has a relatively flexible cure envelope. The minimum cure is 10 hours at 85ºC (185ºF) and rapid cure is 60 minutes at 120ºC (248ºF). Other cure temperatures and times are given in the Working Properties section. ST 94 SPRINT™ works by first applying a vacuum to the laminate stack to remove all air. It is recommended that an ambient vacuum is applied prior to cure, to fully evacuate the laminate stack. The temperature is then increased so that the matrix resin reduces in viscosity and wets the evacuated reinforcement within the laminate. A dwell can be used at the “infusion” temperature to ensure good laminate quality. The temperature is then further increased to cause the matrix resin to cross-link and is then held at the cure temperature until the cross linking process is complete. Once this is achieved heating is removed so that the temperature is reduced under natural cooling. The vacuum must be maintained throughout the cure until the part has been cooled to 40ºC (104ºF).
- TYPICAL CURE PROFILES: The successful use of these cure schedules will depend on part size laminate construction. Heat up rate and dwell periods need to be tailored to take consideration of oven capacity, thermal mass of tool, laminate construction etc. Data in the table below is based on laminate temperatures, air temperatures may need to be higher. It is recommended that Gurit is contacted for further advice before utilising any of the suggested cure cycles. Ultra Slow Cure Cycle single sided SPRINT™
Storage & Handling+
When stored sealed & out of direct sunlight.
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It is recommended that ambient temperature storage is below 22°C (71°F) as higher storage temperatures will induce premature self-impregnation or resin wet-out of the reinforcement. This may impair the air breathing properties of the material. While self-impregnation will vary from product to product, most SPRINT™ materials stored at ambient temperatures will only start to self-impregnate after approximately three weeks. All SPRINT™ materials should be stored in a freezer when not in use to maximise their useable life, since the low temperature reduces the reaction of resin and catalyst to virtually zero. However, even at -18°C (0°F), the temperature of most freezers, some reaction will still occur. In most cases after some years, the material will become unworkable. To avoid condensation on the rolls allow to reach room temperature before unwrapping.