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ELFOAM® P300 is a 3.0 lb/ft3 (48 kg/m3), rigid, unfaced, closed cell polyisocyanurate foam supplied as blocks, sheets and fabricated shapes for a variety of insulation, core material and carving applications. Polyisocyanurate foam (polyiso) is similar to polyurethane foam but offers greater dimensional stability over a wider service temperature range.

Functions: Core Material

Chemical Family: Polyisocyanurates

Core Type: Thermoset Foam

Color: Teal

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Identification & Functionality

Additives Included
Chemical Family
Composite Materials Functions

Features & Benefits

Environmental Data

ELFOAM P300 is specifically formulated to provide excellent physical properties without the use of chlorofluorocarbon (CFC) or hydrochlorofluorocarbon (HCFC) blowing agents. In compliance with the Montreal Protocol and the Clean Air Act, ELFOAM P300 is manufactured with hydrocarbon blowing agents which have no ozone depletion or global warming potential.

Applications & Uses

Plastics & Elastomers End Uses

Typical products incorporating ELFOAM P300 include:

  • Laminated wall and roof panels
  • Commercial and industrial doors
  • Truck/Trailer bodies, shipping containers and railcars
  • FRP panels, tanks and shelters
  • Pultrusion and infusion processes
  • Pipe, tank and vessel insulation
  • Plugs, patterns and carved products

Note that application testing is often required to determine suitability of the foam for a specific application. Potential users should perform pertinent testing to determine the suitability of the product for the intended application. Final determination of fitness of the product for any particular use is the responsibility of the buyer.


Flame Rating
Physical Properties
ValueUnitsTest Method / Conditions
Closed Cell Content (by volume)95%D6226
Coefficient of Linear Thermal Expansion 0 to +250°F (-17 to +121°C)63 x 10-6mm/mm·°CE228
Compressive Strength / Modulus (Parallel to Rise)448 / 9,646kPaD1621
Compressive Strength / Modulus (Perpendicular to Rise5)275 / 5,512kPaD1621
Dimensional Stability6 (length / volume change) (-40°F(-40°C), ambient relativity humidity, 14 days)-0.1 / +0.2%D2126
Dimensional Stability6 (length / volume change) (+158°F(70°C), 97 ± 3% relativity humidity, 14 days)0.5 / +2.2%D2126
Dimensional Stability6 (length / volume change) (+212°F(100°C), ambient relative humidity, 14 days)-0.2 / -0.1%D2126
Flexural Strength / Modulus (Parallel to Rise)606 / 15,082kPaC203
Flexural Strength / Modulus (Perpendicular to Rise5)324 / 6,980kPaC203
Hot Surface Performance at 300°F (149°C)Pass-C411
Polyisocyanurate Insulation RequirementsGrade 2, Type IV compliant-C591
Shear Strength / Modulus (Parallel to Rise)241/ 3,100kPaC273
Shear Strength / Modulus (Perpendicular to Rise5)206 / 2,756kPaC273
Surface Burning Characteristics 7 Smoke Developed, thicknesses up to 6 in (15.2 cm)max. 250-E84
Surface Burning Characteristics7 Flame Spread, thicknesses up to 6 in (15.2 cm)25-E84
Tensile Strength / Modulus (Parallel to Rise)413 / 11,789kPaD1623
Tensile Strength / Modulus (Perpendicular to Rise5)344 / 7,263kPaD1623
Thermal Conductivity, k-factor4 Aged 10 days at 158°F (70°C)0.027W/(m·°C)C518
Thermal Conductivity, k-factor4 Initial at 75°F (24°C)0.024W/(m·°C)C518
Thermal Conductivity, R-value per inch4 Aged 10 days at 158°F (70°C)0.96(m2·°C)/WC518
Thermal Conductivity, R-value per inch4 Initial at 75°F (24°C)1.06(m2·°C)/WC518
Water Absorption (by volume)0.6%C272
Water Vapor Transmission4.4ng/Pa·s·mE96

Physical Properties:

  • 1 -  Data shown are typical values obtained from representative production samples. For specific property ranges, consult the Indianapolis Sales Office.
  • 2 - All properties measured at 73 ± 4°F (23 ± 2°C) unless otherwise indicated.


Typical Values:

  • 3 - To be used only as a guide for design engineering purposes. Potential user is responsible for performing pertinent tests required to determine product suitability for the intended application.


4 -  k-factors and R-values vary with age and use conditions. Contact Indianapolis Sales Office for values at other mean temperatures.

5 - Represents the lowest typical value across all axes related to Perpendicular to Rise performance. Contact the Indianapolis Sales Office for additional information.

6 - Frequent and severe thermal cycling can produce dimensional changes significantly greater than those stated here. Special design consideration must be made in applications that cycle frequently.

7 - Published data is not intended to reflect hazards represented by this or any other material under actual fire conditions. This material is combustible when exposed to large fire sources.

Regulatory & Compliance

Chemical Inventories
Compliances and Approvals

ELFOAM P300 meets industry standards, specifications, regulations and technical guidelines put forth by numerous commercial, federal and military entities including ASTM International, Underwriters Laboratories, and the US Departments of Transportation and Defense.

Technical Details & Test Data


ELFOAM P300 is manufactured in bunstock form 24” (61cm) thick; 48” (122cm) wide; and 96” (244cm) long. Cut sheets are offered in thicknesses from 1/8” to 10” (.32cm to 25cm) in 1/32” (.08cm) increments. Custom sizes and fabricated parts up to 24” (66cm) thick, 48” (122cm) wide and 192” (488cm) in length are available for customers wanting to eliminate in-house cutting, handling, and scrap disposal.

Design Considerations

ELFOAM P300 is designed for use in environments where temperatures range from -297 to +300°F (-183 to +149°C). However, in non-laminated applications where temperatures exceed 140°F (60°C) and/or have relative humidity above 70% as well as in processes where frequent and severe thermal cycling occurs, allowances for foam dimensional changes may need to be incorporated into engineering design. Regardless of operating conditions, a qualified design engineer should review all foam applications. ELFOAM, like all cellular plastics, will degrade with prolonged exposure to sunlight. To prevent such degradation, foam materials should be covered. Other barriers to protect exposed foam surfaces from the elements and to meet applicable fire and safety regulations may also be required.

Safety & Health


All persons who work with ELFOAM products should follow proper handling procedures. The ELFOAM Safety Data Sheet (SDS) contains information about proper handling, storage and use of this material. A copy of this document may be downloaded at or obtained by calling the Indianapolis Sales Office.

Packaging & Availability


All ELFOAM product support, samples, pricing and orders are coordinated by the Indianapolis Sales Office. Please call (800) 545-1213 for details. ELFOAM product data sheets may also be downloaded at