VFI-4281 78 D Polyurethane Casting Plastic

VFI-4281 78 D Polyurethane Casting Plastic is a high-impact urethane plastic with high heat deflection and tensile strength. This material works well when vacuum-degassed and pressure-potted to provide a repeatable, uniform, void-free cast. It is a multi-faceted plastic capable of being used in rapid prototyping, production parts, and equipment housings for large part runs. VFI-4281 has a working time of 6-8 minutes.

Physical Properties	Test Method	Test Results
Hardness Shore D	ASTM D2240	78 D
Tensile Strength	ASTM D638	8850 psi
Tensile Modulus	ASTM D638	250,000 psi
Elongation	ASTM D412	10%
Flexural Strength	ASTM D790	12,300 psi
Flexural Modulus	ASTM D790	281,000 psi
Shrinkage Linear (12"x1/2"x1/2")	ASTM D2566	<0.01 in/in
Izod Impact, Notched	ASTM D256	0.72 ft-lb/in
Izod Impact, Unnotched	ASTM D256	9.20 ft-lb/in
Heat Deflection Temperature (@ 66 psi)	ASTM D648-18	199.04°F ± 2°F

Liquid Properties	Test Method	Test Results
Liquid Density A Side	ASTM D2939	9.5 g/mL
Liquid Density B Side	ASTM D2939	8.9 g/mL
Mixed Liquid Density	ASTM D2939	9.3 g/mL
Specific Gravity A Side	N/A	1.14 g/mL
Specific Gravity B Side	N/A	1.07 g/mL
Mixed Specific Gravity	N/A	1.11 g/mL
Ratio by Volume (A:B)	N/A	100A:53.3B
Ratio by Weight (A:B)	N/A	2A:1B
Mixed Solids by Volume	ASTM D2697	100%
Viscosity A Side	ASTM D2196	100 cps
Viscosity B Side	ASTM D2196	2300 cps
Mixed Viscosity	N/A	300 cps
Pot Life	N/A	8 minutes
Gel Time	N/A	10 minutes
Flash Point	ASTM D56	>200°F

Thickness Requirements

To create the necessary exotherm to fully cure the part, it cannot be poured less than a quarter inch thick at room temperature. For thinner pours, you must elevate the mold and molding temperature to 115°F.

Storage/Shelf Life

Store between 60°F – 90°F in a clean, dry building. The shelf life of unopened containers is 12 months after the date of manufacture. Once opened, use immediately. If storing after opening, both sides must be nitrogen purged immediately after use.

Mold Preparation

Release agents are recommended for any molding application to extend the life of the mold, and for prototyping urethane molds, it is a requirement. Heated molds are not recommended for this product or any mold over 120°F because it will cause an uneven cure.

Mixing

The B side (Poly) must be premixed once daily before each use, being careful not to introduce extra moisture or air. The A side (Iso) does not need to be mixed.

Prepare a container that is an appropriate size for degassing. It is recommended to contain at least 2/3 of headspace in order to vacuum degas. Pour measured A side into the container and promptly follow by pouring measured B side into the same container. Mix until uniform by hand or power mixer. Mixing, vacuum degassing, and pouring must all be completed before the end of the pot life.

Post Cure

After an initial cure of 16 hours at room temperature, heat curing at 150°F for 24 hours will achieve full physical properties. Physical properties at room temperature will be delayed until after 7 days and may not fully develop without post-curing in an oven.

Precautions

This product contains isocyanate, which may irritate the skin and is toxic if inhaled as particulate matter. Avoid prolonged breathing of vapors or repeated skin contact. Use only with adequate ventilation. Do not add foreign material to the product. See Safety Data Sheet for complete safety data.