Measuring Outgassing in Adhesives

Interview conducted by Stuart MilneAug 7 2015

Venkat Nandivada, Manager of Technical Sales at Master Bond Inc. talks to AZoM about the ASTM E595 industry standard for measuring outgassing in adhesives and their line of one and two component silicones that meet this standard.

Can you please tell us a little about Master Bond and what separates it from other adhesives manufacturers?

For over 40 years, Master Bond has been at the forefront of developing high performance epoxies, silicones, polyurethanes, polysulfides, UV cures and other specialty adhesive systems. Each compound is designed to meet specific application needs and requirements. We serve a variety of industries including aerospace, medical, optical, electrical and electronic, among others, doing our best to comply with the strict parameters and industry specifications these areas require.

What are some of the main considerations when formulating adhesive products for the aerospace industry?

The biggest consideration for most aerospace applications is the NASA low outgassing specification. ASTM E595 is the industry standard test for measuring outgassing in adhesives and other materials. Developed by NASA to screen low outgassing materials for use in space, the test determines the volatile content of material samples placed in a heated vacuum chamber.

Are there any new products that Master Bond has released for the aerospace industry?

Master Bond has just introduced a line of one and two component silicones that meet NASA low outgassing requirements. MasterSil 920-LO, MasterSil 921-LO and MasterSil 922-LO are one part silicone systems that cure at room temperature based on the humidity in the air; where the higher it is, the faster the cure. Our two part silicones include MasterSil 970-LO, MasterSil 971-LO, MasterSil 972TC-LO and MasterSil 973S-LO, which are addition cured systems, meaning that they do not require air for complete crosslinking.

What makes these silicones such desirable products?

In addition to passing NASA low outgassing testing, these systems all offer impressive flexibility, thermal cycling capabilities and high temperature resistance up to 400°F or 500°F depending upon the system. These silicones also have a low durometer making them well suited for use with sensitive electronic parts.

Select systems such as MasterSil 972TC-LO and MasterSil 973S-LO feature a thermal conductivity of 7-9 and 9-11 BTU•in/ft²•hr•°F [1.01-1.30 and 1.30-1.59 W/(m•K)], respectively. MasterSil 973S-LO is a silver filled, electrically conductive system that offers a low volume resistivity of 0.004 ohm-cm at room temperature.

This family of silicones is easy to handle with many systems delivering superb flow properties. However, MasterSil 922-LO and MasterSil 973S-LO have non-drip paste consistencies. The single component systems along with MasterSil 971-LO all offer excellent light transmission properties for a variety of optical applications.

Can these systems fill the need for highly specialized applications?

As a matter of fact, MasterSil 920-LO is ideal for conformal coating and encapsulation applications. Conformal coatings enhance the reliability and long-term performance of electronic assemblies by providing superior protection against dust, dirt, abrasion and other contaminants.

Another example is MasterSil 973S-LO’s ability to be used as a formed-in-place gasket material. Its paste viscosity enables precise application and it can cure in wide and deep cross, greater than 1 inch.

Other than aerospace, where can this line of products be used?

The aforementioned properties make these silicones well suited for many applications across the electronics, optical, fiber-optics and OEM industries.

How do you see the adhesives market developing in line with the increased materials development within the aerospace industry? How will Master Bond be a part of this change?

The demand for high strength, light weight adhesives that meet strict industry standards is constantly increasing. Master Bond engineers are continuously formulating new adhesives, sealants, coating and potting compounds to meet these specifications. Select formulations meet the previously mentioned NASA low outgassing requirements as well as the FAR standard 14 CFR 25.853(a) for flame retardancy.

About Venkat Nandivada

Venkat Nandivada has been the Manager of Technical Sales at Master Bond Inc since 2010. He has a Masters in Chemical Engineering from Carnegie Mellon University.

He analyzes application oriented issues and provides product solutions for companies in the aerospace, electronics, medical, optical, OEM and oil/chemical industries.