Introduction

EPON Resin 826 or EPON Resin 862/LS-81K Curing Agent system is based on an epoxy resin cured with an anhydride. LS-81K Curing Agent is a formulated methyltetrahydrophthalic anhydride (MTHPA) containing an internal mold release additive and a cure accelerator, LS-81K is manufactured by Lindau Chemicals Inc.

This resin system’s combination of low viscosity, good pot life and fast gelation characteristics during cure make it favorable for wet processing fabrication of composite parts.

• In Pultrusion processes, it processes at high line speeds with low pull loads, and

it yields good surface quality. No internal release agents are needed because they

are already incorporated in the curing agent.

• In Filament Winding processes, good fiber wet-out is achieved because of the resin system’s low viscosity. It also has a relatively long pot life.

Neat resin casting data indicate this resin system has a unique balance of Tg, tensile and flexural strength, while providing high toughness properties.

Suggested Uses

• Composite structures
• Civil engineering
• Sporting goods
• Transportation
• Electrical
• Marine

Features

• Non-MDA
• Non-styrene
• Low viscosity
• Long pot life
• Good surface quality
• Retention of properties up to 105 °C (221 °F)
• Good elongation
• High toughness
• Good electrical properties

Chemical Description

• EPON Resin 826 is a bisphenol A epoxy resin
• EPIKOTE Resin 862 is a bisphenol F epoxy resin
• LS-81K is a specially formulated methyltetrahydrophthalic anhydride with an internal mold release agent

Typical Properties

Table 1 / Typical Properties

Method

Units

EPON Resin 826

EPON Resin 862

Epoxide equivalent weight

D-1652

eq/g

178-186

166-177

Viscosity @ 25 °C (77 °F)

D-445

cP

6,500-9,500

2,500-4,500

Color

D-1544

Gardner

1 max.

2 max.

Density @ 25 °C

lbs/gal

9.7

9.9

Specific gravity @ 25 °C, (g/cc)

g/cc

1.16

1.18

Method

Units

LS-81K Anhydride Curing Agent

Anhydride equivalent weight

eq/g

185-195

Viscosity @ 25 °C (77 °F)

D-2196

cP

200-300

Density @ 25 °C

lbs/gal

9.8-10.0

Specific gravity @ 25 °C

g/cc

1.18-1.20

Units

826/LS-81K

862/LS-81K

Mix ratio

pbw

100/100

100/100

Viscosity @ 25 °C (77 °F)

cP

1230

897

Density @ 25 °C

lbs/gal

9.8

9.9

Specific gravity @ 25 °C

g/cc

1.18

1.17

Typical Handling Properties

Table 2 / Typical neat resin properties of EPON Resin 826 or EPON 862/LS-81K Anhydride Curing Agent

Units

826/LS-81K

862/LS-81K

EPON Resin 826

pbw

100

—

EPON Resin 862

pbw

—

100

LS-81K Anhydride Curing Agent

pbw

100

100

Viscosity @ 25 °C ¹

cP

1230

897

Time to double initial viscosity @ 25 °C ¹

hrs

8

5.5

Working life @ 25 °C, time to reach:

1,000 cP

hrs

N/A

1.0

2,000 cP

hrs

4.6

7.0

3,000 cP

hrs

>8.0

>9.0

Gel time ²

@ 150 °C (302 °F)

sec.

80

82

@ 180 °C (356 °F)

sec.

32

28

@ 200 °C (392 °F)

sec.

18

18

Graph 1 / EPON Resin 826 or 862/LS-81K Anhydride Curing Agent viscosity @ 25 °C (77 °F) – 10 gram sample

Graph 2 / EPO N Resin 826 or 862/LS-81K Anhydride Curing Agent cure sweep @ 5 ° C per minute

Typical Cured State Properties

Table 2 / Typical cured neat resin system casting properties of EPON Resin 826 or 862/LS-81K Anhydride Curing Agent

826/LS-81K

862/LS-81K

Method

Units

Value

Value

Cure Schedule

Step 1

hrs/°C (°F)

1.5/66 (151)

Step 2

hrs/°C (°F)

1/85 (185)

Step 3

hrs/°C (°F)

3/150 (302)

Tg by rheometrics (max. tan delta)

D-4065

°C (°F)

136 (277)

126 (259)

Tensile Strength, at Break

D-638

psi

10,700

10,700

Tensile Elongation, at Break

%

5

5

Tensile Modulus

ksi

396

413

Flexural Strength

D-790

psi

17,800

17,800

Flexural Modulus

ksi

439

457

Fracture toughness, Kq

E-399

psi-in ^.5

1187

1234

Moisture absorption ¹

% wt.

3.01

2.97

Specific gravity

D-792

g/cc

1.20

1.23

Electrical Properties

Dielectric constant

@ 1 Meg Hz & 23 °C

D-150

3.17

3.24

Dissipation factor

@ 1 Meg Hz & 23 °C

D-150

0.018

0.016

Dielectric strength

D-149

Volts/mil

432.3

418.8

Suggested Formulations

Units

Pultrusion

Filament Winding

EPON Resin 826 or EPON Resin 862

pbw

100

100

LS-81K Anhydride Curing Agent

pbw

100

100

ASP-400P ¹

pbw

10-20

N/A

Composite Fabrication / Pultrusion

The properties of this low viscosity and quick cure system at elevated temperatures provide the pultruder with a processable epoxy resin system. The unique resin system characteristics translate into high line speeds, low pull forces and good surface quality. All features are advantages of fabricators who desire the higher performance properties of epoxy resins.

Mixing – A high shear mixer is recommended to insure complete dispersion of the filler. Mixing time should be kept to a minimum to avoid excess heat build-up of the resin system, as this can reduce the working life of the system.

Resin bath – The resin impregnation bath temperature should be as close to 25 °C (77 °F) as possible to maximize working life.

Process– The EPON Resin 826 or EPIKOTE Resin 862 /LS-81K Curing Agent will cure at die temperatures ranging from 170-180 °C (338-356 °F). The optimum temperatures will depend on parameters such as part thickness, line speed, and preheat temperature. The epoxy part will react to a high degree of cure during the pultrusion process. A post cure, however, may enhance the properties.

Composite Fabrication / Filament Winding

The low viscosity and long working life of the resin system make it desirable for Filament Winding thin wall parts.

Mixing – A high shear mixer is recommended to insure complete mixing. Mixing time should be kept to a minimum to avoid excess heat build-up of the resin system, as this can reduce the working life of the system.

Resin bath – The resin impregnation bath temperature should be as close to 25 °C (77 °F) as possible to maximize working life. However, elevated temperatures may be required to obtain the appropriate viscosity for fiber wet-out.

Process– The 826 or 862/LS-81K system will cure at mandrel/oven temperatures of 80-150 °C within 1-3 hours. The optimum temperatures will depend on parameters such as part thickness.

Storage

Recommendations regarding storage conditions can be obtained by visiting our web site at www.hexion.com