The cross-linking of these foams at the molecular level is achieved by either a chemical or irradiation process. Both cross-linking processes serve to create bonds between the polymer chains which in turn form a three-dimensional structure. It is the three-dimensional cross-linked structure of these materials that significantly improves their physical properties including compression strength, compression set, tensile strength, and thermal stability.
The inherent properties of these polyethylene-based materials also make them resistant to chemical degradation. Additionally, because these materials are closed-cell they have low water absorption characteristics and the lower densities have good buoyancy characteristics.
Cross-linked polyethylene foams are manufactured using both low-density and high-density polyethylene resins depending on the physical properties required of the specific foam. The attributes of the foams can also be modified by the addition of vinyl acetate. Adding vinyl acetate creates a polyethylene/vinyl acetate copolymer with increased, softness, flexibility, and resilience. The higher the percentage of vinyl acetate in the copolymer the softer the resulting foam will be.
Cross-linked polyethylene foam formulations can also be customized for different markets and end-uses. Antibacterial, static-dissipative, and fire-retardant agents can be added to the foams in order to produce materials with characteristics that are beneficial in specific market segments.
Cross-linked polyethylene foams are manufactured in both continuous roll and bun forms. Cross-linked foam rolls are extruded at a thickness from 1/32” to approximately .5” thick. The most common roll width is 60”. The rolls can be manufactured in densities ranging from 2 lb/cubic foot to 20 lb/cubic foot. Flextech distributes and fabricates Sekisui Voltek’s Volara and Armacell’s Oletex roll foam product offerings.
Cross-linked foam buns are manufactured in a range of thicknesses, width, and lengths depending on the material manufacturer and specific density and grade of material. Buns can come in thickness of 1” to 4” and be 40” to 60” wide and 48” to 72” long. The density of the bun foams can range from 1.5 lb/cubic foot to 18 lb/cubic foot. Flextech distributes and fabricates cross-linked polyethylene buns from Zotefoam’s Azote product line, Sekisui Voltek’s Minicel products, and Armacell’s Oletex brand.
The thermoplastic nature of cross-linked polyethylene foams allows them to be heated and three-dimensionally shaped. This process is generally referred to as thermoforming. Flextech utilizes three unique foam thermoforming processes to create three-dimensional formed parts. The three methods are compression molding, encapsulation molding, and vacuum forming.
Because of their exceptional physical properties, cross-linked polyethylene foams are utilized in a wide range of markets and applications. Flextech utilizes cross-linked foams to manufacture medical device packaging, medical device components, orthopedic bracing and supports, protective padding for athletic products, and padding for military/tactical gear, just to name a few. There are countless other applications for this very versatile family of foam materials.
We invite you to connect with our technical sales team to learn more about cross-linked polyethylene foam as well as our other materials and capabilities. We can be reached at 952-345-0012 or [email protected]. We look forward to hearing from you.