Product test methods, formaldehyde

Hardwood plywood products are decorative in nature and are designed for interior use. Over 95X of all hardwood plywood is made with urea-formaldehyde adhesives. Responding to concerns about formaldehyde and certain wood products, test methods for measuring surface emissions were developed in the early 1980 s. Emissions from most hardwood plywood and particleboard products have decreased 65% to 95% in recent years primarily by use of low emitting UF adhesives and/or scavengers. Good correlation has been demonstrated between product test methods and indoor levels of formaldehyde in experimental manufactured homes. Decorative surface finishes can act to either increase or decrease surface emissions, depending on the nature of the finish and the substrate. 

G. Gramp, W. Groah. "Evaluation of the relationship between formaldehyde emission from particleboard mobile home decking and hardwood plywood wall paneling as determined by product test methods and formaldehyde levels in experimental mobile homes." U.S. Dept. of Housing and Urban Development, 1982. 

Singh Walcott, J. St. Pierre, C. Ferrel, T. Garrison, S. Groah, w. "Evaluation of the Relationship Between Formaldehyde Emissions from Particleboard Mobile Home Decking and Hardwood Plywood Wall Paneling Determined by Product Test Methods and Formaldehyde Levels in Experimental Mobile Homes" Clayton Environmental Consultants, Inc., Report, Prepared on Contract No. AC-5222, H.U.D., March, 1982. 

Product tests. Clearly, the best product test is full-scale testing of finished panels under actual use conditions. This has been done (27,38) but is expensive, because several full-sized panels of each product must be pre-conditioned at constant temperature and humidity for at least a week. The next best approach is to test product samples in air chambers under standardized conditions. A summary of such methods is contained in Table I. A very large effort has been made over the last three decades world-wide to develop quick, reliable and meaningful product tests. Wittmann (16), Zartl (20), Plath (17), Verbestel (1, Neusser (21,22), Roffael (25), HUD, the U.S. Forest Products Industry (39,40), many standaraization organizations (41-43) and others have published many viable methods, but the testing involves a combination of complex factors and there is simply no single test that fulfills everybody s specific needs. Table I list some of the currently accepted test methods for formaldehyde emission from particleboard, plywood and medium density fiberboard. 

Sma11 Sea Ie Test Method for Determ i n i ng Forma Idehyde Em i ss i on from Wood Products, Two Hour Dessicator Test, FTM-1," National Par id eboard Association, Hardwood Plywood Manufacturers Association, Formaldehyde Institute and U.S. Department of Housing and Urban Development, Federal Register, 1982, 48, 37169. 

Small scale test method for determining formaldehyde emissions from wood products, two-hour desiccator test, FTM 1, Reston, VA. 

Large-Scale Test Method For Determining Formaldehyde Emissions From Wood Products — Large Chamber Method, FTM 2-1983 National Particleboard Association Gaithersburg, MD, 1983. 

These test chambers can be incorporated to the enzymatic methods for formaldehyde determination. Formaldehyde emissions of a product, or mix of products, to the ambient air can be collected in distilled water or 1% sodium bisulfite as the absorbing solution. After collection, formaldehyde samples are analyzed as described above. In the mobile home simulator test method (2J, double or triple impingers, which are placed in series, should be used in order to collect all of the formaldehyde vapor. The test conditions should simulate the actual environment. Several factors such as temperature and relative humidity of the system including the specimens and background of formaldehyde in the test chamber, affect the precision and accuracy of the results. It has been shown that a 7 C change in temperature doubles the emission level (L). The temperature of the test chamber should be... 

Formaldehdye generation and recovery studies 3.) Air exchange measurement techniques 4.) Preconditioning of test boards 5.) Temperature effect on chamber formaldehyde concentrations 6.) Relationship of popular quality control test methods to the large chamber 7.) Loading, air exchange rate, and wood product combination effects on chamber formaldehyde concentrations 8.) Chamber Round Robin studies between Georgia-Pacific s chamber and other outside lab chambers 9.) Chamber concentrations and its relationship to actual field measurements. 

Based on our experience, it appears that a quality control method which correlates to the chamber for a particular product type does not always work for all products. The only universal test method for all products is the large scale test chamber. A quick and reliable formaldehyde quality control test method is becoming more important as formaldehyde levels in the chamber fall below 0.15. A universal small scale test method (Q.C.) does not seem to exist at this time. However, the Small Scale Test Chamber may be the closest to fulfilling that purpose. 

Actual formaldehyde measurements made while performing field investigations using the CEA 555 Air Monitor were corrected to 25 C. Wood samples removed from the investigation site were returned to the laboratory, and the corresponding quality control test method was used to determine formaldehyde content of the specific wood product. The formaldehyde value obtained from the quality control test method was then used to determine the chamber concentration from the established correlations (Figures 13 14). 

Small Scale Test Method for Determining Formaldehyde Emission from Wood Products - Two Hour Desiccator Test - FTM-1-1983" National Particleboard Association/Hardwood Plywood Manufacturers Assocition, 1983. 

Equilibrium Jar Method, Colorimetric Determination of Formaldehyde Using Chromotropic Acid Reagent for Product Testing - GPAM 203.6" Georgia Pacific Corporation, 1979. 

Tentative Test Method for Emission of Formaldehyde from Wood Products - 24 Hour Desiccator Method" National Particleboard Association, 1980. 

The purpose of this study was to evaluate laboratory formaldehyde release test methods for predicting real-life formaldehyde air concentrations human exposure levels, and health risk. Three test methods were investigated the European perforator test, the gas analysis method at 60 C and 3% RH, and the gas analysis method at 23 C and 55% RH. Different types of particleboard bonded with urea-formaldehyde and urea-melamine-formaldehyde resins were tested. The results were used to rank boards as a function of test method, conditioning, short-term humidity, and temperature variations during storage. Additional experiments were conducted in small experimental houses at a Dutch research institute. Our conclusions are that relative ranking of products is influenced by the test method and by change in relative humidity. The relationship between test method and release in real-life situations is not clear. In fact, it seems impossible to use laboratory measurements to predict real-life product performance of board if the board is not fully in equilibrium with the atmosphere. 

The incidence of perceptible formaldehyde in homes, offices and schools has caused widespread uncertainty about the safety of living with formaldehyde. This uncertainty was enhanced by the large scale installation of urea formaldehyde foam insulation (UFFI) because a substantial part of this material was made from small scale resin batches prepared under questionable quality control conditions, and was installed by unskilled operators (10). The only reliable way to avoid such uncertainty is to know the emission rate of products and develop a design standard that allows prediction of indoor air levels. The first and most important step in this direction was achieved with the development and implementation of material emission standards. As indicated above, Japan led the field in 1974 with the introduction of the 24-hr desiccator test (6), FESYP followed with the formulation of the perforator test, the gas analysis method, and later with the introduction of air chambers (5). In the U.S. the FTM-1 (32) production test and the FTM-2 air chamber test (33) have made possible the implementation of a HUD standard for mobile homes (8) that is already implemented in some 90% of the UF wood production (35), regardless of product use. 

The friability of a rigid foam is not an easy property to determine, and it is seldom used as a quality control measurement. However, for certain materials such as phenol-formaldehyde foam it can be a useful tool in formulation work to ensure that the product is suitable for the application area. In certain instances the test method is best adapted to the foam being tested, for example the time duration of the test may be shortened if the material is being abraded too harshly. 

Plywood panels produced in Europe for building purposes use urea-formaldehyde (UF), melamine-urea-formaldehyde (MUF) and phenol-formaldehyde (PF) adhesives. Standards requirements are not focused on direct properties of these adhesives but properties of the end-products (closely linked to adhesive properties and process parameters). Nevertheless, EN 314-1 (2005) [1] defines a test method for the evaluation of the bonding quality of plywood panels, but also blockboards, laminated boards and laminated veneer lumbers (LVL), by shear testing before and after ageing treatments. Relevant requirements are specified in EN 314-2 (1993) [5] which also defines the ageing treatments required for the intended service class of the tested panel as shown in Table 1. 

Chemical analysis is very suitable for well-defined and known substances if reliable analytical methods are available for the specific allergens. Simple and quick test methods make it possible for clinical departments to analyse products brought in by the patients. Analytical methods requiring specialised laboratory equipment or expertise must be carried out in specialised laboratories, and this may cause time delay or incredibly high expenses for the clinical routine work. For example, nickel and formaldehyde can be detected by simple tests methods, but chromate and epoxy demand methods requiring specialised laboratory equipment and expertise. 

Tests often cited in the medical literature for the detection of formaldehyde in various products are the chromotropic acid and acetylacetone tests. Flyvholm et al. (1996 and 1997) describe both tests and present the results of a study in which both of these tests were used to detect formaldehyde. The majority (63%) of the 1134 products tested with the methods were cosmetics and toiletries and another 18% were household products. Some resin-finished fabrics were included. For 81% of the products, the two tests gave the same results. 

Performance and durability of wood products bonded with isocyanate and urethane adhesives have been the subject of several investigations. The strength of composition board is generally determined by its modulus of rupture (MOR), which is a flexure to break test its modulus of elasticity (MOE), or stiffness and its internal bond strength (IB), or tensile strength. These tests are run on dry and on water-soaked or wet samples, and are described in ASTM test method D 1037. As compared to phenol-formaldehyde adhesives, composition boards prepared with isocyanate or urethane adhesives are reported to display similar or superior initial strengths. Moisture resistance of isocyanate-bound par-... 

For the easy care finishes the residual formaldehyde should not be more than 16 ppm for babies and 75 ppm for adults in the next-to-skin garments however, for all other products, including interior textiles, the limit is 300 ppm. The test method followed is EN ISO 14184-1. 

Ammonium chloride is analyzed by treatment with formaldehyde (neutralized with NaOH) and the product HCl formed is analyzed by titration using an acid-base color indicator such as phenolphthalein. Alternatively, it may be mixed with caustic soda solution and distdled. The distillate may be analyzed for NH3 by titration with H2SO4 or by colorimetric Nesslerization or with an ammonia-selective electrode (APHA, AWWA, WEF. 1995. Standard Methods for the Examination of Water and Wastewater. 19th ed. Washington, DC, American Pubhc Health Association). The presence of ammonia or any other ammonium compound would interfere in the test. The moisture content in NH4CI may be determined by Karl—Fischer method. 

In Chaps. 2 to 6, a case study is developed in order to apply and test the methods developed along the whole book. To this purpose, the reaction between phenol and formaldehyde for the production of a prepolymer of phenolic resins has been chosen for several reasons. In fact, this reactive system is widely used in different forms for the production of different polymers moreover, it is characterized by a noticeable production of heat and by a complex kinetic behavior. Such features represent strong challenges for controlling and monitoring tasks. 

Fast pyrolysis of biomass provides a method for the production of phenolics that has the potential to replace at least 50% or more of the phenol in phenol-formaldehyde thermosetting resins. The gel tests indicate that the P/N fractions from pine sawdust pyrolysis with paraformaldehyde have shorter gel times than commercial plywood resins such as Cascophen 313, even without prepolymer formation. A novolak formulation has been prepared using 1 1 by volume of phenol and P/N fraction and about half of the amount of formaldehyde that would be used than if phenol alone were employed. Very promising resols have also been made with a similar substitution of the P/N fraction for phenol. Wood testing and resin formulation development are ongoing activities. The projected economics suggest that additional research and development of this process are fully warranted. 

Production equipment that cannot be sterilized must be sanitized and disinfected by an appropriate method. This can be done by use of biocides like alcohols (70%), hydrogen peroxide, or formaldehyde-based chemicals or a combination of these. These can either be used for surface disinfections by wiping or spraying or even better by use of gas or dry fog systems for application of the disinfectants. The effect of cleaning and sanitation should be monitored. Microbiological media contact plates can be used to test critical surfaces, as inside the hot cells or glove boxes. The test samples must then be handled and monitored as radioactive contaminated units. 

---