Volume 7 Issue 3 March 2006
Working Together for Quality
Standards for Cellular PVC Profiles and Laminated Finishes
by Rich Walker
Dimensional stability, expressed as a percentage of
linear shrinkage at elevated temperature, is an excellent indicator of any internal or residual stresses that may
have resulted from the extrusion process.
The cellular PVC profile-technically defined as those produced in the presence of physical or chemical blowing agents that cause the original PVC feedstock to foam and reduce its density—is just one of several new fenestration framing materials that have become viable alternatives in the marketplace. It is in the interest of the industry that consensus performance standards be developed or updated to permit objective, performance-based evaluation of competing products.
Window manufacturers can depend on recently released updated performance standards for cellular PVC profiles and laminates for use on plastic profile—respectively AAMA 308-05 Voluntary Specification for Cellular Poly Vinyl Chloride [PVC] Exterior Profiles and AAMA 307-05 Voluntary Performance Requirements and Test Procedures for Laminates Intended for Use in AAMA Certified Plastic Profiles.
AAMA 308-05 serves as the basis for the AAMA Profile Certification Program for cellular PVC profiles. Such certification is a pre-requisite for conformance of plastic-framed doors, windows and skylights with the newly issued and I-code required AAMA/WDMA/CSA 101/ I.S. 2/A440-05 and its predecessors issued in 1997 and 2002.
It is based on years of research and development and experience validating the key factors in the performance of cellular PVC profiles: dimensional stability, weatherability, heat resistance, hardness, density tolerance and lead content. Dimensional stability, expressed as a percentage of linear shrinkage at elevated temperature, is an excellent indicator of any internal or residual stresses that may have resulted from the extrusion process. Weatherability is concerned with color retention under varying North American climate conditions and is based on extensive outdoor weathering studies. Heat resistance deals with the ability of the surface to resist blistering, cracking or delamination at elevated temperatures. Shore D hardness measurements provide relative ranking of profile surface hardness and its resistance to scratching, denting and other physical damage. Density tolerance relates to the actual weight of the profile as compared to its intended weight. Lead content tests ensure that the compound used to make the profile does not contain lead in excess of that allowed by U.S. safety standards (less than 0.02 percent by weight).
The Big Finish
Cellular PVC profiles—in fact all plastic profiles—may include decorative finishes such as laminates, paint or co-extrusions applied to their surface. AAMA 308-05, therefore, also includes in-process quality control guidelines for the production of laminated and organically coated cellular PVC profiles. These specifically set forth requirements for in-process quality control sampling and testing of laminated profiles per AAMA 303 Voluntary Specification for Rigid Poly [Vinyl Chloride] [PVC] Exterior Profiles. These tests cover impact- resistance, dimensional stability and strength of the adhesive bond between the cellular PVC substrate and the surface laminate. In the case of organically coated profiles, production samples must be tested for impact and heat resistance and for coating color, texture, thickness, hardness, adhesion and chemical resistance per AAMA 613 and 614.
AAMA 307-05 is designed to work in tandem with AAMA 308-05 when laminated decorative finishes are applied. It requires that laminates be tested per ASTM protocols for weathering performance, impact strength, chemical resistance (muriatic acid, mortar and detergents), sealant compatibility and lead content. Indeed, AAMA 307-05, as well as separate standards for paints and coatings, is designed to work in tandem with other standards. These include profiles made of solid PVC, ABS, fiberglass, thermoplastic/cellulosic composite materials and reinforced thermoplastics, in addition to those made of cellular PVC.
Rich Walker serves as executive vice president for the American Architectural Manufacturers Association in Schaumburg, Ill. He may be reached at email@example.com.
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