Enhanced TDS
Knowde-enriched technical product data sheet
Identification & Functionality
- Chemical Family
- CASE Ingredients Functions
- Technologies
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Features & Benefits
Applications & Uses
- Markets
- Applications
- Compatible Polymers & Resins
- Applications
NADIC methyl anhydride (NMA) is a liquid alicyclic anhydride commonly used to cure epoxy resins in many challenging applications, including fiber reinforced composites used in high performance aerospace and military applications, as well as mechanically demanding applications like filament wound bearings. The excellent electrical properties and high temperature performance make NMA-cured epoxies outstanding materials for encapsulating electronic components and circuits. NMA demonstrates many excellent characteristics when used as a curing agent for epoxy resins, including:
- Ease of handling
- Compatibility with solid and liquid epoxy resins
- Long pot life
- Low viscosity mixtures
- Low volatility
- Freedom from odor
- Less reactive than amines
- Easily catalyzed to match any process requirements
- Low exotherm
Epoxy resins cured with NMA demonstrate outstanding properties, including:
- Light color
- Excellent electrical characteristics, including arc resistance
- High heat distortion temperature (HDT) and glass transition temperature (Tg)
- Thermal stability
- Minimal shrinkage when cast
- Excellent hardness and impact strength
NMA may also be used as a building block for unsaturated polyester resins.
Properties
- Physical Form
- Appearance
- Pale yellow to tan liquid
- Typical Properties
Value Units Test Method / Conditions Specific Gravity 1.20-1.25 g/cc D-102 (ASTM D 4052) Viscosity max. 300 cP D-150F Boiling Point 132 ° C ASTM D86 Flash Point 135 ° C ASTM D93 Molecular Weight 178.2
Technical Details & Test Data
- Vapor Pressure as a Function of Temperature
- Specific Gravity as a Function of Temperature
- Modifying Other Anhydrides
As a liquid, NMA is useful in modifying other anhydrides to lower their freezing points and make them easier to handle. The following plot shows how NMA lowers the freezing point of five other anhydrides.
- Cure Catalysts
The effect of benzyldimethylamine (BDMA) catalyst on mix stability was studied using the following formulations:
System Catalyzed Uncatalyzed EPON Resin 828 (Momentive) 100 100 NADIC methyl anhydride 88.7 67.3 Benzyldimethylamine (BDMA) 1 0 Epoxy homopolymerization is a significant side reaction for uncatalyzed systems, so anhydride demand is less.
Viscosity as a function of time is summarized in the following plot.
- Anhydride Level
Most applications use between 60-90 phr NADIC methyl anhydride with liquid epoxy resins. Most high performance applications utilize 80-90 phr where high levels of heat resistance, chemical resistance, or high strength are required.
Examples
A study was done to examine the effect of anhydride level on performance. The levels of NADIC methyl anhydride chosen were 75, 85, and 93 phr to cure EPON Resin 828 (Momentive) using 1 phr BDMA catalyst. The cure cycle was 2 hours at 93°C with a post-cure of 2 hours at 204°C.
The following results were obtained:NMA, phr 75 85 93 HDT, °C 129 132 102 Tensile Strength, psi 11,000 11,000 11,600 Elongation, % 3 2.7 2.8 Flexural Strength, psi 18,900 20,700 24,500 Flexural Modulus, ksi 520 570 560 Compressive Strength, psi 18,700 19,400 20,500 Dielectric constant, at 25°C 1MHz 3.6 3.8 3.7 Dissipation factor, at 25°C 1MHz 0.01 0.02 0.02 These results display a typical response for heat distortion temperature, (and glass transition temperature) where there is an optimum anhydride level for a given formulation (epoxy and catalyst) and cure cycle. This is shown in the following plot:
The anhydride level has different impact on other performance properties as shown below for flexural and compressive strength:
The effect of NADIC methyl anhydride level on heat distortion temperature and weight loss after 1000 hours exposure at 200°C for cured bisphenol A epoxy resin (with 1 phr tris(dimethylamino methyl) phenol as accelerator has been reported and is reproduced below. It can be seen that the optimum level of NMA is different depending on which property is more important.
- Cure Cycle
The cure cycle used has a dramatic effect on system performance. This cure cycle includes the initial time and temperature used to cure the formulation, as well as all post-cure times and temperatures used to improve performance properties. This is important because longer cure times and higher cure temperatures promote increases in crosslinking. Higher crosslinking results in higher levels of mechanical strength and chemical resistance.
Examples
In one study, 100 parts EPON Resin 828 was combined with 90 parts NMA and one part BDMA to evaluate the impact of cure times from 4 to 200 hours. The cure cycles and performance results are summarized as follows:
Time (hours at 150°C)) 4 24 200 HDT, °C 112 128 144 Tensile Strength, psi 11,600 10,500 12,100 Tensile Modulus, ksi 500 500 400 Elongation, % 3 2.7 4.5 Wt. gain after 24 hr water boil 0.98 0.67 0.67 Wt. gain after 4 hr acetone boil 3.2 1.9 0.9 The HDT results and chemical resistance results are summarized in the following plots.
Samples were then tested at -25°C, at room temperature, and at 100°C. The following charts summarize results for tensile strength and elongation:
Safety & Health
- Health Hazards
These anhydrides are primary skin and eye irritants. Avoid contact with skin, eyes, and clothing. Use only with adequate ventilation. In case of contact, follow the procedures outlined in the SDS. Generally, these procedures include immediately flushing the affected skin or eyes with copious amounts of water for at least 15 minutes.
In the case of eye contact, get medical attention. Wash contaminated clothing before reuse. Follow the recommendations in the SDS for personal protective equipment when handling these materials. At a minimum, these procedures typically include protective chemical goggles, impenetrable gloves, and measures to avoid breathing chemical vapors.
Storage & Handling
- Storage
It is recommended that NADIC methyl anhydride is stored between the temperatures of 18° C (85° F) and 40° C (104° F) to avoid freezing, although the material is not affected by freezing. If material does freeze, thaw at a temperature below 40° C and mix well before using. Store in a dry place and keep container tightly closed to prevent absorption of atmospheric moisture or contamination. The presence of moisture could cause free acid to form in the anhydride. NMA will react with water to form diacids. This is normally undesirable, so NMA should be stored in such a way that it is carefully protected from moisture contamination. For more details on the design of bulk storage for NMA, consult the Dixie Chemical Company brochure “Epoxy Curing Agent Storage Requirements.”