Explanation of Relevance of Physical Properties

See Glossary for further definition.

Acidity: The quality of a material to be acidic (pH under 7) when exposed to moisture or water producing a red/pink reaction to litmus paper. Insulation that creates an acidic environment when exposed to water can contribute to corrosion of the system. Dyplast's polyisocyanurate and expanded polystyrene products do not react with water, creating neither a basic nor acidic environment; therefore they do not contribute to corrosion.

Alkalinity: The quality of a material to be basic or alkaline when exposed to moisture or water producing a blue reaction to litmus paper. A pH over 7. Insulation that creates an basic (alkaline) acidic environment when exposed to water can contribute to corrosion of the system. Dyplast's polyisocyanurate and expanded polystyrene products do not react with water, creating neither a basic nor acidic environment; therefore they do not contribute to corrosion. ASTM C871 provides the methodolgy for the determination of water-leachable chloride, fluoride, silicate, and sodium ions in thermal insulation materials.

Appearance: Appearance is important in all insulation applications to the extent it reflects on the quality of the product and the installation. Appearance is also important in exposed installations within commercial buildings not only for aesthetic reasons but also for compliance with building codes. Dyplast's polyisocyanurate and expanded polystyrene products each have a pleasant tan or white (respectively) appearance, yet are never installed as exposed "raw" components. Rather polyiso and EPS are installed as part of an insulation system consisting either of barriers and jacketing in a pipe/equipment system, or within framing and wall members within a wall.

Bacterial Growth Resistance: See Resistance to Bacterial Growth. An insulation's resistance to microbial growth is determined in accordance with ASTM C1338.

Breaking load: In some installations the insulation material must "bridge" over a discontinuity in its support. The Breaking Load is the force necessary to create structural failure in a "bridging" condition. Insulation with higher Flexural Strength maintain their structural integrity under more rigorous bridging conditions. ASTM C203 is the test method for breaking load and flexural properties of block-type thermal insulation. Dyplast ISO-C1 products have excellent breaking load characteristics. See Flexural Strength.

Buoyancy: Buoyancy is an upward force on an object immersed in a fluid (i.e. a liquid or a gas), enabling it to float or at least to appear to become lighter. If the buoyancy exceeds the weight, then the object floats. Dyplast's polyiso and expanded polystyrene products are very bouyant, have virtually no tendency to absorb water, and can be used in flotation applications.

Capillarity: A wick-like action whereby a liquid will migrate vertically through material, in a upward direction. The movement of the liquid material against gravity is the result of surface tension. Must be considered when material may be in contact with liquids. Dyplast's polyisocyanurate and expanded polystyrene products have no capillarity tendencies.

Cell Uniformity and Circularity: With respect to closed cell rigid foam plastics, the tendency for cells to be of similar spacing and dimension, and for the cells to be uniformly circular. Improved uniformity and circularily contributes to foam strength as well consistency between "parallel to rise" and "perpendicular to rise" strength measurements. Closed cell rigid foam insulation with poor uniformity and circularity may have good strength in one dimension, but poor in another, potentially leading to variation in the strength of cut sheets and shapes depending on direction of the cut.

Chemical Resistance: The ability of the insulation to withstand the presence of materials - such as acids, bases, water, salt water, and fuels - that can deteriorate an insulation. Chemical resistance is important primarily when the atmosphere is salt or chemical laden. Dyplast's ISO-C1 polyisocyanurate products have excellent chemical resistance.

Closed Cell Content: The ratio (expressed as a percentage) of closed cells (versus open) to the total number of cells. Since closed cells contain insulating gases that increase the thermal resistance of the insulation, a higher closed cell content equates to higher insulating value. A higher closed cell content also contributes to compressive and flexural strength.

Corrosion resistance: Corrosion can occur if incompatible components of an insulation system are in contact with each other, if water intrudes into the insulation system, or if the insulation system is installed in a corrosive environment. Corrosion may attack the jacketing, the insulation hardware, or the underlying piping or equipment. Depending on other factors, chloride, and galvanic, acidic or alkaline corrosion may occur.

Since system components are normally designed to be compatible with each other, the primary concern is either the interface between the insulation and the equipment being insulated (e.g. metal pipe or duct surface) or the insulation jacket that may be exposed to a corrosive atmosphere. ASTM C 665 governs suitability for insulation interfaces with steel, copper and aluminum. Galvanized steel can also be tested. Polyisocyanurate and expanded polystyrene insulation have been found to be compatible with virtually all metals used in pipe, ducts, and equipment. There excellent moisture resistance also contributes to minimizing corrosion. Click here for more on corrosion.

Coefficient of expansion and contraction: Enters into the design and spacing of expansion/contraction joints and/or the use of multiple layer insulation applications.

Combustibility: One of the measures of a material's contribution to a fire hazard.

Compressive strength: That property of an insulation material which resists any change in dimensions when acted upon by a compaction force. Compressive Strength is Important if the insulation must support a load or withstand mechanical abuse without crushing. If, however, cushioning or filling in space is needed as in expansion/contraction joints, low compressive strength materials are specified. Dyplast's ISO-C1 polyisocyanurate has excellent compressice strength, with successively higher density products exhibiting higher compressive strengths.

Density: The weight per unit volume of a substance. A insulation's density affects several properties of that material, especially strength, weight, and thermal resistivity. Dyplast Products carries a full line of varied densities for both its polyiso as well as its EPS products.

Dimensional stability: Ability of insulation to maintain size under conditions of varying moisture, humidity, and relative stresses. Significant when the material is exposed to atmospheric and mechanical abuse such as twisting or vibration from thermally expanding pipe. ASTM D2126 covers procedures for the thermal and humid exposure of rigid cellular plastics. ISO 2796 is also a test for dimensional stability of rigid cellular plastics. Dyplast's ISO-C1 product line has excellent dimensional stability, making it ideal for low temperature and cryogenic piping applications.

Emissivity "E": The ability of a surface to radiate energy as compared to that emitted by an ideal black body at the same temperature. Since Dyplast Products' insulations are not used without either vapor barriers or jacketing, it is the emissivity of the insulation system surface (barrier or jacket) that is relevant. Emissivity is significant when the surface temperature of the insulation must be regulated as with moisture condensation or personnel protection. Emissivity is also important for reflective insulations. Click here for more information on Emissivity.

Flame spread retardancy: Flame spread (as well as smoke developed) ratings should be considered for indoor installations since the International Mechanical Code as well as some other local codes generally require a Fire Spread/Smoke Development rating of 25/50 per ASTM E84 for exposed insulation (primarily duct and pipe applications) installed in commercial buildings. Yet E84 cautions "that products which melt and drip and require artificial support present unique problems and require careful interpretation of results." Flame Spread can also be measured per UL723 and NFPA 255. In Europe, compliance is governed by DIN 4102. Click here for further discussion. Dyplast's products meet or exceed ASTM E84 ratings of "25" fire spread.

Flammability: In the U.S., this is referred to as Flame Spread. (See Flame Spread). In Europe, compliance is governed by DIN 4102.

Flexural Modulus: Ratio of maximum fiber stress to maximum strain, within elastic limit of the stress-strain diagram obtained in the flexure test. The flexural modulus is a measure of elasticity, or the ability for the material to be deformed and return to its original shape. An alternate term is the Flexural Modulus of Elasticity. The flexural modulus of Dyplast's ISO-C1 line of polyiso products is generally higher than competing polyisos, and increases as density increases.

Flexural Strength: The flexural strength of a material is its ability to resist deformation under load, or how much you can bend the material before it starts to break. For materials that do not break, the load at yield, typically measured at 5% deformation/strain of the outer surface, is reported as the flexural strength or flexural yield strength. The general term for bending stiffness is flexural rigidity, which is the product of the material's elastic modulus and the cross section moment of inertia. The flexural strengths of Dyplast's ISO-C1 line of polyiso products is generally higher than competing polyisos, and increases as density increases.

Fungal Growth Resistance: See Resistance to Fungal Growth

Hot Surface performance: The term "hot-surface performance" has reference to a simulated use-temperature test in which the heated testing surface is in a horizontal position, in accordance with ASTM C411. This test method refers primarily to high-temperature insulations that are applicable to hot-side temperatures in excess of 200°F (93°C), and tests materials at 250°F. Dyplast's ISO-C1 product line passes the C411 test.

Linear Expansion/Contraction: Changes in linear dimensions of a plastic are composed of reversible components, as well as irreversible components, on which are superimposed changes in length due to changes in temperature, moisture content, curing, loss of plasticizer or solvents, release of stresses, phase changes and other factors. The curing of polyisocyanurate and expanden polystyrene foams is the process during which the foams equalize and stabilize, thus resulting in a foam with minimal subsequent linear or volume expansion. See Volumetric Expansion/Contraction. Dyplast's polyiso and EPS proprietary formulations result in foams with excellent linear and volumetric stability. Both reversible and irreversible expansion in "as-installed" environments are expected to be nil. This is important on applications involving cements and mastics, such as in pipe insulation applications.

Permeance and Permeability: Permeability refers to the tendency for water vapor to be transported through a layer of insulation. Permeance is the unit measure of permeability, whose units are perm-inch. See Water Vapor Permeance. Dyplast's ISO-C1 polyisocyanurate has exceptionally low permeability, thereby aiding in minimizing water vapor transmission through the insulation and thus minimizing condensation. An effective vapor barrier with close to zero permeance is the primary condensation protection in low temperature and cryogenic piping systems.

Resistance to chemicals: See Chemical Resistance

Resistance to corrosion: See Corrosion Resistance.

Resistance to fungal or bacterial growth: Particularly necessary in food or cosmetic process areas, but also important in insulation systems installed in habitable areas since allergen and disease control is important, as well as aesthetic appearance. Each component of the insulation system should be resistant to fungal and bacterial growth since the weakest link will likely determine overall performance re: this criteria. Insulation coatings and jackets must present a smooth surface which resists fungal or bacterial growth in food process areas. Both polyisocyanurate and expanded polystyrene insulations have no nutrient value; no other thermal insulations exhibit better resistance to fungal and bacterial growth. An insulation's resistance to microbial growth is determined in accordance with ASTM C1338.

Resistance to ultraviolet light (UV) : Ultraviolet light can result in degradation of certain materials used in outdoor insulation systems. Polyvinylchloide pipe jacketing without special UV stabilizers, for example, is likely a less satisfactory choice than metal jacketing. Dyplast's ISO-C1insulation will discolor under exposure to UV light, but its performance will not deteriorate.

Service Temperature: Upper & lower temperatures within which the material must retain all its properties. The service temperature of Dyplast's ISO-C1 is typical of other polyisocyanurate products.

Shear Modulus: Shear modulus, sometimes referred to as the modulus of rigidity, is defined as the ratio of shear stress to the shear strain. Shear modulus is usually measured in ksi (kips per square inch) or GPa (gigapascals).