# krclin**~** Performance Applied

June 25, 2012

Ms

. Lynn Vendinello Chief, Fibers and Organics Branch Office of Pollution Prevention and Toxics U.S. Environmental Protection Agency 1200 Pennsylvania Ave. N

.W. Washington, D.C. 20460

RE: New Data Supporting Critique of Frihart Study

Dear Ms. Vendinello,

On January 10, 2012 Georgia-Pacific Chemicals submitted a critique ofthe study entitled Formaldehyde Emissions from ULEFand NAFBonded Commercial Hardwood Plywood as Influenced by Temperature and Relative Humidity ("Frihart study")

. The critique was submitted on behalf of GP Chemicals, LLC, Momentive and Ardin, Inc., the three major formaldehyde-based resin producers in North America. The letter explained our concerns with the relevance and condusions ofthe Frihart study and respectfully requested that EPA refrain from basing any rule-making decisions on the study's findings

.

In further support ofthe concerns outlined in the January 10th critique, a new study was conducted by Ardin, Inc., Particleboard Formaldehyde Emissions and Decay under Elevated Temperature and Humidity Conditions. As detailed in the attached document, the new Ardin study uses accepted regulatory and industry testing practices and is thus far more relevant than the Frihart study. The Ardin research dearly shows under extreme environmental conditions that all panel emissions were generally 2-3 times greater than "standard conditions" for adhesive types, and further that the emissions decayed significantly at a similar rate for adhesive systems in both the extreme and the standard environmental conditions. Most Significantly, panel emissions from all products under extreme conditions were well within California Air Resources Board Phase II emission levels within 25 days from date of panel making and exposure ofthe panels to an extreme environment did not adversely affect emissions when the panels were re-equilibrated to standard ASTM D-6007 conditions.

Based on the Arclin study findings, we recommend that the EPA maintain a performance based standard aligned with the California Air Resources Board (CARB) ATCM, including provisions that foster and open and unbiased competitive environment for both resin and panel producers, allow choices and availability to consumers, and enhance innovation of all adhesive types

.

The Ardin and Frihart studies both attempted to better understand the impact on formaldehyde emissions from different adhesive systems when subjected to extreme environmental conditions. However, the Ardin study differs significantly from the Frihart Study in that it employs test methods, procedures and protocols that are more similar to actual in service conditions as well as consistent with

475 28th Street. PO Bol( 270· Springfield. Oregon 97477

. USA

. P 541.746.6501 f541.746.6273. \WIV.'. j LeornCARB approved and industry accepted practices

. The new Ardin study addresses the deficiencies in the Frihart study as follows :

1. Emissions test method : The emissions data collected in the Frihart study used a modified EN 717-3 method

. The EN 717-3 has not been approved by CARB nor is there an established correlation between the EN 717-3 method and the ASTM E-1333 1

. The Ardin study uses the ASTM D-6007 testing method which is approved for direct correlation to the ASTM E-1333.

2

. Static versus dynamic equilibrium: The Frihart study used a static or stagnant testing environment which does not represent product emissions expected in normal use

. The ASTM D6007 method used by Ardin is a dynamic test method in which a state of equilibrium is reached using a designated number of air exchanges reflecting normal indoor environmental conditions

.

3. Extreme conditions oftesting: The Frihart study used unrepresentatively extreme floutdoor" temperature and humidity test conditions. The Ardin study used a temperature of 85°F and a relative humidity of 75%. The Ardin test conditions are also extreme, but were based on an actual worst case scenario. Specifically, the worst case city (Houston, Texas), which has an average summer temperature of 84°F and relative humidity of76.5%. Since temperature and humidity vary cydically throughout the day, the average ofthe daily low and high were used.

4. Ratio of edge to surface during testing: The Frihart study does not test products in a way that would be representative of how panel surfaces are exposed in actual use. In the Frihart study, there was extremely high edge exposure ofthe panels thus potentially exaggerating emission results

. The Ardin study tested panels realistically in a manner they would be utilized as defined by worst case scenarios in manufactured homes for panel loading as well as edge exposure (correlation to ASTM E-1333)

.

5. Emission decay over time : The Frihart study had no long term VOC emission decay data. The only data provided showed cumulative emissions over a four day period leading to speculation rega rding potential emission results from UF resins

. In contrast, the Ardin study does an indepth evaluation of how particleboard panels bonded with various types of adhesives perform
over a much longer period oftime. The Arclin data shows panel emissions from the moment of manufacturing through a 50 day period. Under extreme conditions, all panels regardless of adhesive technology, showed an initial 2-3 fold increase of emissions followed by a significant decay curve resulting in significantly low emissions by the end of 50 days

. Additionally, when these same panels were equilibrated back to flstandard" conditions at the end of 50 days, they behaved identical to panels which had been maintained at standard conditions showing there
were no adverse or detrimental effects on panel emissions when exposed to extreme conditions

. Panel emissions from all products under extreme cond itions were well within CARB Phase II emission levels within 25 days from date of panel making and all panels were the same

1 ASTM E-1333 isthe primary CARB approved test method used for emulating performance ofwood based panels within interior and the test method mandated in Section 601, Part (a)(7) and Part (a)(10) ofthe Public Law 111-199 for measuring forma ldehyde emissions

.

475 28th Street. PO Bm 2l0. Springfield. Oregon 97477. USA. P 541.746.6501 f541.746.6273. www

... ciin.comemission level (approximately 0.025 ppm or less) at standard conditions after a 45 day decay period.

6. Information on UF resin: The Frihart study provides no information on the UlEF-UF adhesive formulations or panel making procedures reducing Frihart conclusions regarding emission phenomena and hydrolysis concerns to nothing more than speculation. The Arclin formulations ofthe formaldehyde-based systems were known by the authors, and when possible CARB exempt "certified" UlEF adhesives were chosen for evaluation.

The Arclin study used responsible testing methods and parameters to better understand the emission characteristics of panels made with various adhesive types. The study showed the emission characteristics of panels made with various types of resins, when exposed to standard and extreme environmental conditions, respond in asim ilar and predictable manner.

Because ofthe similarities in performance ofpanels made with adhesive types, we endorse an unbiased performance based product emissions standard for regulatory purposes for all panel producers and resin suppliers. Additionally, we request the EPA refrain from using the Frihart study as a basis for justifying any regulatory decisions.

Regards,

# -=~~ Technical Director Decorative and Interior Resins tom.holloway@arclin.com

4TS 28th 511eet

- PO 800. 270· Springfield. Orego,", 97417 • USA , P 541.746.6501 fH1.74li 6213 • WNW .rom

# Particleboard Formaldehyde Emissions and Decay under Elevated Temperature and Humidity Conditions

Darren Riedlinger, Pierre Martin and Tom Holloway



### Arclin LiSA, 

### 47528111 

### St. Springfield, OR 97477



### March 28, 

### 20J2



### Abstract Particleboard panels were prepared using four different resin chemistries: melamine-ureaformaldehyde, urea-fonnaldehyde, phenol-fonnaldehyde, and polymeric diphenylmethane diisocyanate. Matched panels of each chemistry where then exposed to either a control conditioning environment maintained at 77 "F, 50'% RII or an elevated conditioning environment maintained at 85 OF, 75% RH. Emi%ions were monitored over 50 days and their respective decay rates \vere modeled as an exponential decay function. At the conclusion ofthe monitoringperiod panel physical properties were measured and compared.
Key words: Particleboard, formaldehyde**emi~sions**



### Introduction

Product emission standards based on ASTM 

### E 1333 for composite panels have hIstorically been tested at humidlties and temperatures standardized to average indoor environmental conditions. This paper examlnes formaldehyde emissions from particleboard made with various adhesive types tested under extreme conditions

over a 45-50 day period using a modified ASTM 6007 method. Environmental conditions during testing \vere based on high outdoor temperature and humidity conditions experienecd during summer months in the Southeastern Cnited States (1). Since temperature and humidity vary cyclically throughout the day, the average ofthe daily low and high experienced in the most extreme
summer location was used for the experimentcorresponding to a relative humidity of75% ami

a temperature 0[85 

### CF. Laboratory made particleboard panels, conditioned and tested for emissions, were bonded with four diffcrcnt adhesive types: a pbenol-fonnaldebyde (PF) certified to meet California Air Resource Boards (ARB) ultralow-emitting-fonnaldehyde (ULEF) standard, a polymeric diphenylmethane diisocyanatc (pMDI), a urea-formaldehyde (UF) and a melamine-urea-formaldehyde 

### (.\IIUF). 

### Experimental

Panel Construction Laboratory panels were made from wood furnish gathered from a pal1icleboard plant which manufactures panels using only pMDI adhesives, ensuring the furnish would be free from panel recycle sources (mitigated as much

as possible) that may have an influence on fomlaldehyde emissions. Sixteen panels total WIth four of each adhesive type were constructed. Panels were made With 50% surface material and 50% core material to a targeted density o[ 44.0 pounds per cubic foot. All panels were 

### /2 inch nominal thickness \'lith a targeted final thickness of 0.570 inches. Press temperatures were held constant at 345 

### OF for all adhesive types. The pMDI and amino resin systems v,·ere pressed with identical cycle-times;
Page 1 0[8

### however, the pMDI panels had slightly higher moisture contents to ensure cure. The only variance in press time was with the PF in which
a longer cycle-time was used to ensure curing of the adhesive. None of the panels were sanded priorto formaldehyde testing. Although exact adhesive and panel making recipes for these panels will not be revealed due to the proprietary nature of the adhesives and recipes, the MUF, PF, and pMDI represent a close approximation to recipes used in the composite particleboard panel industry. The UF
was made at the same formaldehyde to urea ratio as the MUF and with the same panel making recipe, however, it has not been used commercially. Some panel making characteristics are presented in Table 1.

Table 1: Panel making 

### details

Adhesive Press Press time Density Thickness type temp. atposition (lbs·lft· .) (in.) (1F) (sec) PF 345 240 43.15-43.80 0.572-0.573 UF 345 170 43.85-44.40 0.570-0.571 MUF 345 170 43.95-44.25 0.568-0.570 pMDI 345 170 44.00-44.65 0.566-0.568 

### Formaldehyde Emissions Testing 

### After removal from the hot press and cooling to ambient temperatures, one set of panels was cut into 6.75 x 6.75 inch samples and edge sealed using aluminum tape. They were then sealed in a polyethylene bag for later analysis in Arclin's Springfield, Oregon laboratory which had environmental conditions of 85 of 

### (29.44 0C) and 75% relative humidity. A duplicate set, treated similarly, were cut to a dimension of 7.87 x 9.06 inches and sent to Arclin's Ste. Therese, Quebec lab for testing using standard ASTM 6007 environmental conditions of 77 OF (25°C) and 50% relative humidity for comparative purposes. Each testing environment consisted of an outer conditioning room containing one or more stainless steel testing chambers, capable of maintaining fixed airflow rates during emissions testing. Testing of all panels began once both labs received their samples and continued at periodic intervals thereafter. Because the two testing environments utilized in this study were located in different research laboratories--each with unique infrastructure and analytical capabilities, some slight differences existed in the respective methodologies. For the control environment, a single Dynamic Micro-Chamber (DMC) was employed with an internal volume of44 liters. The airflow rate was maintained at 3.60 Umin, resulting in ASTM D 6007 airflow-rate to sample-surface-area ratio (Q/A) of 1.173 rnlh. Panels were stored in individual conditioning bays located within the conditioning environment between analyses and were transferred to the DMC between 10 and 30 minutes before sampling. During sampling, 1.0 Umin ofthe chamber make-up air was diverted into an impinger containing 20 ml of a 1 % solution ofsodium bisulfite for a period of83 to 135 minutes. Immediately after sampling, two duplicate 4 ml aliquots of each impinger solution were reacted with chromotropic acid and analyzed using a Spectronic 301 spectrophotometer at 580nm, which had been previously calibrated using a series of formaldehyde solutions ofknown concentration (R2
= 

### 0.999). Background formaldehyde levels, tested periodically throughout the test were consistentlybelow 7parts perbillion. For the elevated temperature/humidity environment, four ASTM D 6007 small chambers were employed, each having an internal volume of 69.24 liters. Mass-flow controllers attached to the outlet port of each small chamber maintained an airflow rate of 1.152 Umin, resulting in an ASTM D 6007 Q/A ratio of 1.176 m/h. Panels were stored in individual conditioning bays located within the conditioning environment between analyses and
were transferred to a randomly chosen small chamber five hours before analysis. Following equilibration, air sampling occurred over 60 minutes, during which time airflow was diverted from a bypass line to a Supelco S 1 0 DNPHPage 2 of8coated sihca solid phase extraction column (sampled air volume equaled 69.2

. ,i_ O.Iliten). The cartridges \vere then sealed in Mylar bags, stored at 5 "C and**anal~i7ed** by IIPLC within

one week. Both room and small r.;hamher background formaldehyde In**d~** were measured periodically throughout the expenment and were consistently bell)\\. 3 parts perhl1lion. IIPLC fOlmaldehyde quantification \/vas pcrfonned uSll1g an adaptation of 

### l\lOSll :V1cthod 2() 16. HPLC peak area response factors

were calihrated for each analysis set lIsmg five D'\IPH-formaldehyde standards at concentrations between 

# o 15S6 and 96.9 flg D'\IPH-formaldehyde per ml. Linear regress10n coelTic1ents were greater than 0.')9')9 for all analyses. Measured fonnaldehyde**emi:.~i()ns** are expre)sed in molm ppm, adjustcd to con"elate w1th the ASTM E1333 large chamber dynm11lc test method. This corrdation was performed het\\'een Ardin·s Springfield laboratory and the**Compo~ite** Panel Association's 1..:.1333 large chamher ming 12 sets of matched sper.;1I11en 'whose emissions ranged bctwcen D.D 1 and D.15 ppm. A correlation factor of 0.7775 largechamher ppm-'small-chamber ppm was established with an R2 equal to O.9H7. A later eOlTelation study vv'as then pcrfonned hetween**Arelil1·~** Springfield and St. Therese laboratories using 12 specimens whosl: l:111lssions ranged hetween 0.01 and 0.11 ppm. In thi:. l:ase, t\\,oway linear rcgrr.;ssiun of the two laboratories· 111easurcmellts yielded a :.igmfieant (P < .DOO 1) intercept eoefllcient and the St. Therese values

were**adJu~ted** mmg the fol1ov>':ing correlation equation (R=

- (J.971 H): [1] Springfield [1333 ppm - (11441 x 5t, Therese ppm)­ 001185 

### Results and Discussion

Control envirunment /ormaldehvde emissiolls. Dynamic-airflow fonnaldehydl:**emi:.~i()ns** for particleboard panels maintamed at 77**~F** and 50(% Rll arl: presented 1n F1gure 1. Each panel**~ct** had been sealed in polyethylene immediately after pressing and 1nitml measurements INere taken less than one hour after unsealing. ror all four resin chemistries, this initial emisslOns measurement was significantly eir.;\-atr.;d relatlve to mbsequent samples and can likely he attributed 10 the n:kase of entrained formaldehyde, which**i~** tYP1Gtl when panels are scaled immediately after hot-pressmg. For example, the .MUr and LF-honded paneh initially generated emissions orO.llS and 0.097 ppm. respecthely, but had fallen to hetween 0.045 and 0.OS5 ppm after two**day~** of conditioning and then declmed steadily throughout the study. By the end the monitoring pcnod, cm1SSlOns from the \IUF panel were O.(J24 ppm and em1SSIO[lS from the lJF panel were 0.013 ppm-both well helow the AR13 phasl: II limit. The PF and pMDT-bonded panels also exhib1ted relatively hIgh emissions tor the imtial me1bUfement and decayed to 0.014 and 0.023 ppm.**re~pcr.;tlvely,** after two day:. of conditionmg. Ultimate emission levels

aner 50**day~** ofmonitormg were D.O(l3 ppm tor the pMDI panels and ncar ;tern ppm for the PF panch. A:. pMlJI contams no labile formaldehydc, the p:\1DI panels" emissions represent background levels arising solely' from the \\oml fUJ111Sh used !Il thi5**~hldy---either** cndogenom formaldehyde generated by wood itself(and**po~sibly** exacerbated by hot-pres:.mg) (2-4), or from formClldehyde containing recycle materi;ll in our source mill"s fum1sh supply (despite our efforts to mitigate ib prcscnce). It is therefore notcworthy that the phellol!e re5in sy:.tem. although not a non-added formaldehyde (l\AF) :.ystem,**cons1~tently** exhibited lov,cr eJlllssions than the pV1DI system.

Pagc 3 ors- - - - - - 

### §0.14**~** 0. 12 ' UJ E 0. 10 •

,. - - ­ "0 2J 0

.08 

### '"**~** 0.06 

# , • • • 5 u 0.04

- 

### '" MUF 

# • UF 0 pMDI 

## • PF

------- y**~** 0.02



### .... 

# •**_ ~** **~~~ ~** **~ ~ _** **~~~ ~~~** **UJ O.** **OO~** __**~O** __**~~ - -**  __**. ~** **~ ~~** **~**

### __**. ._** **_ __ _** **_ _** **_ _** **_ _** **_ _ _** **_ _** **_ _** **_ _** **_ _** **_** o ill m**~ ~** **~** Conditioning Time (days) Figure 1: Particleboardemissions decay rate under standard temperature and relative humidity conditions

T emperature %RH T

- T f

- - t ft

· J: 85.0 cc: *- 75.0**~ ~** **~** 

### 9 t**~** 

### M u: I 1 I I • 65

.0 "

VI 

## ,. g 0

. 14 MUF**~** 0.12 UF 

# • E



# .. •

.. 

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# ., ­ pMDI w 0

. 10 

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### __.-
- - - - .. u 0

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# 81 tJ

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# •**UJO.OO~_ ____** **·-** ______**~~ ~** **- - ~~~~** **~~ ~** **~ ~~** **'- -'** **- - ~** **' ~~~** **-- ~~** **~~~ - -** **~~ ~~~** **- - ~** **~_ ~** **-. _~** **~~ ~~** **~** o ill m**~ ~** **~** Cond itioning TIme (days) Figure 2: Particleboardemissions decay rate under elevated temperature and relative humidity conditions. Top: Room (solid lines) and small chamber (discrete box plots) temperature and humidity data

. Box plots represent the minimum, lower quartile, median, upper quartile and maximum small chamber condition observed during each 60-minute board sampling. Bottom: E1333 correlated small chamber emissions for particleboard panels prepared using MUF, UF, pMDl or PF adhesives

. ' Solid' versus 'open' data points distinguish between each oftwo replicate panels manufactured and analyzed for each resin type.


### Elevatedenvironmentformaldehyde emissions: Formaldehyde emission levels for those panels maintained at 85 OF and 75% RH are presented in Figure 2. Under these conditions

our environmental controls were not as precise

as those used for the 77 OF, 50% RH conditioning environment; therefore, actual temperatures and relative humidities ofthe room and small chamber are provided in the upper portion of Figure 2. Over the course of the entire monitoring period, the average conditioningroom temperature was 84.1 OF (0' = 

### 1.74) and the average room humidity was 73.6% (0' = 

### 8.88). Unlike the temperature ofthe conditioning room, which could be maintained close to its average value with only occasional deviations, the conditioning room humidity oscillated regularly with approximately three cycles per hour. However, the small chambers buffered these oscillations and remained relatively constant: during sampling, the average conditions within the small chambers were 86.2 OF (0' = 

### L.03) and 74.7% RH (0' = 

### 2

.71)

. As illustrated in Figure 2, although all panels (at least initially) generated higher emissions in the 85 OF, 75% RH elevated environment than in the 77 O F, 50% RH control environment, the relative trends were the same: the amino-based chemistries (MUF and UF) exhibited the highest emissions, the pMDI system was intermediate and the PF systems emissions were lowest. During the initial two days of conditioning the emissions from all panels declined. However, between days two
Page 4 of8Figure 3: Comparisons of emissions in elevated and control environments, overlaid with exponential decay models

E
Q. .3­

V> c o**~** E w -0 2 '"**~** o U '" 

### '"
rl W 

### '"

and four, emissions actually increased slightly in all panels

- a phenomenon not observed in the control environment. In 

### the 75% RH elevated environment, panels would likely take longer to approach their equilibrium moisture content than in the 50% RH control environment, and this may suggest that increasing panel moisture

was counteracting an otherwise natural decay in emissions over time. Following day four, the emission levels from all panels again begin to decrease, with the magnitude of this decrease being greatest in the higher emitting systems. For example, at day four emissions from MUF and UF-bonded panels were both approximately 0.13 ppm and decreased steadily throughout the remainder of the 45-day monitoring, ultimately reaching levels below 0.06 ppm. Emissions from the pMDI panels were near 0.06 ppm at day four and decreased to approximately 0.027 ppm by the end of the study

. Lastly, emissions from the PF panel, which were already below 0.03 ppm after four days conditioning, decreased to 0.023 ppm by the end ofthe study. 0.14

-
0.12

0.10

0.08

0.06

0.04

0

.02

0.14 o 0 0.12**~O** ' '(J0,S 0 0.10 (JI'"cO,
0.08 0 "be..

0.06 

# • • 0.04

0.02 • pMOI (ontrol o pMDI elevated

0"

- _-JQ.

o 

# • o



## --­ :::

Conditioning Time (days) 

### Emissions decay modeling andcomparison: From the raw data presented in Figures 1 and 2 alone it is difficult to make direct comparisons between emissions in the elevated environment and control environment at specific points in time, due to both noise in the datasets and a lack of measurements at identical conditioning times in the two environments. Panel formaldehyde emissions have generally been observed to decay exponentially with time (5). Each dataset was therefore fitted with an exponential decay function to average out measurement errors associated with any individual datapoint and allow us to interpolate emissions levels at arbitrary points in time

. Model coefficients and fitting details are providedin Appendix A. 

### Emissions in the elevated and control environment are compared for each resin in Figure 3 and are overlaid with the fitted exponential decay models. Based on these models, emissions levels after 7,30 and 45 days

were calculated and are provided in Table 2. Relative emission differences for the MUF, UF
Page 5 of8Table 2: Calculated emissions values based on the exponential decay models at various conditioning times. 

### For each conditioning time the relative difference between the elevated and control models (,ratio') and absolute difference ('f\.') 

### are provided.
Day: 7 30 45 Resin control elevated ratio D. control elevated ratio D. control elevated ratio D. MUF UF PF pMDI 0.057 0.109 0.063 0.108 0.011 0.027 0.023 0.048 1.94 0.053 1.71 0.045 2.55 0.016 2.10 0.025 0.035 0.029 0.002 0.009 0.068 1.93 0.033 0.067 2.35 0.039 0.021 10.05 0.019 0.023 2.63 0.014 0.026 0.050 1.93 0.024 0.017 0.050 2.88 0.032 0.001 0.018 22.50 0.017 0.005 0.014 3.02 0.009


### and pMDI systems were similar, with emissions in the elevated environment being approximately two- to three-times higher than in the control environment, regardless of conditioning time. However, because emissions decayed exponentially over time, the actual magnitude ofthe emissions difference between the elevated and control environment**(~)** 

### also tended to decrease exponentially. Unlike the MUF, UF and pMDI systems, the ratio between the elevated and control emissions for the PF system increased throughout the study, with a 22.5-fold difference in emissions after 45 days. Note, however, that emissions from the PF control system were extremely low; this unique trend observed for the PF panels could in part relate to greater measurement errors as emissions approached our analytical limits of detection.
Panel re-equilibration andphysicalproperties: Finally, after 50 days of conditioning our Springfield testing environment was adjusted back to the control conditions of77 OF and 50% RH and those panels previously maintained in

our St Therese control environment were shipped back to Springfield. These panels, along with the panels previously exposed to the elevated environment, were re-conditioning in Springfield for seven days and their emissions

are presented in Table 3. The Springfield emissions measurements for the control panels (column iii) 

### are similar to final measurements made in St. Therese (column i), 

### indicating good agreement between the two laboratories. Furthermore, after equilibrating to 77 OF, 50% RH, emISSIOns from those panels previously maintained in the elevated environment (column iv) 

### were almost identical to the final emissions from the control panels (column iii), 

### suggesting that exposure to elevated temperatures or humidities does not permanently alter a panels emissions characteristics. Although panel emISSIOns were not permanently affected, conditions in the elevated environmentwere severe enough to affect all the panels' physical properties. After reequilibrating for 7 days at 77 OF and 50% RH, internal bond (IB) strengths were measured for both the control and elevated conditioning environment panels. IE values of those panels exposed to the control environment met M-2 grade ANSI standards, with the exception ofthe UF resin which only met ANSI M-l grade. In contrast, IE values of all panel chemistries exposed to the elevated environment were 11­ 15% lower and exhibited some surface quality issues related to raised grain.

Table 3: Panel emissions in Springfield laboratory at 77 OF, 50% RH

ii iii iv Resin St. Therese Springfield Control, re-tested (control) (elevated) in Springfield at

final final 77°F, 50% RH Elevated, reconditioned to 77°F, 50% RH
PF pMDI UF MUF 0.001 0.023 0.008 0.003 0.028 0.009 0.013 0.059 0.019 0.024 0.055 0.021 0.010 0.010 0.021 0.022



### Page 6 of8

### Conclusions

Pilrticiehoard p;mcls ",,:ere prepared usmg four different**re~1I1** chemistries and their emissions were monitored over 50 days in both

a 77 "F, 50% Rli control conditioning environment ami a X5 

# cr, 75%) RH elevated environment. The elevated conditionmg cnvmmment had moderatc effect on panel**phY~lcal** properties, negatively Impacting surface quallty and slightly reducing Internal bond strengths. While subjected to the elevated environment. emissions \vere generally 2-3x greater than what was observed in the control environment hO\veyer, In both em· lronments panels**cm1SS1011~** decayed exponentially throughout the study regardlc:.>, of resin**ehcmi~try.** Furthcnnore, the elevated conditioning environment did not appear to permanently Impact**emi~sions** once these panels

were re-equilibrated in a control environment.



### References

I. F()rmaldehyde I:"missions .[rOI/J l./LL"Fand A'AF-Bondcd Commercial IIardw()od Plywood os Ili/lucnced h.Y' rCIl1/Jeratllrc and Reiatil)c HumidifY. Frihart, Charles R, ct at. ()cncva, SwitLeriand, 2010. Proceedmgs of the International Convention of Soclet;.' of Wood SCIence and Tcchnology and LJlllted Nations EconomIc**COmml~S]()n** fi.n Euorpoe. pp. 1-13. 2. FormaldehJdc cmissiol1.l'Fotn solid IHWt/. Myers, Gcorge E and Bochme, C. Macils()n, \Vr: Forest Prod. L 1997, Vol. 47, pp. 45-4X. 3. Volitilc organic compollndl' Ilnd jurma/deh.Y'de il7 nature, 'rvood and H'oud based panels. Rotlael, E. :..1.' Holz Koh vVcrkst, 2006, Vol. 64, pp 144-149. 4. fVoor/-bol"})e fi'Jrmaldchyde vw)'ing l,vith .Ipecie.l", \-vood ;.!,mde, and c(Jl11hial age. \Ycigl, M, et al. s.l.

. Forest Prod. J , 200t), Vol. 59, pro XX-92 5. Versar Inc. Formaldehyde exposure model

-- descriptio/l (jnd del1JolIstmlio/J. CS Environmental Protl:ction Agl:l1cy, 1986. Contrad l\o. 68-02-3968.

Page 7 

### or8

### AppendixA: Formaldehyde emissions decay modeling

Panel emissions were modeled to the exponential decay function

### t: LoglO

### {emissions) 

## =M .

### time + B, resulting in the following model coefficients and regression values:

Treatment MUF elevated MUF control UF elevated UF control pMDI elevated pMDI control PF elevated PF control Slope Intercept R2
-0.0091 -0.8976 0.923 -0.0090 -1.1850 0.782 -0.0089 -0.9053 0.886 -0.0149 -1.0951 0.889 -0.0140 -1.2246 0.752 -0.0183 -1.5161 0.697 -0.0047 -1.5356 0.604 -0.0302 -1.7654 0.951



### Model 

### R2 values are generally lower for those treatments that generated the lowest formaldehyde emissions, reflecting the greater relative error associated with emissions measurements as they approach backgroundlevels and suggesting the need to smooth such datasets before makingreliable comparisons. Despite the low model 

### R2 values for some treatments, visual examination ofFigure 3 suggests that the exponential decay model provides a good approximation of the overall emissions trend for each treatment without overfitting the data and modeling random variations associated with any individual data point.



### t In the case ofthe PF control emissions, three ofthe emissions measurements-after adjusting according to Equation i-wereslightly belowzero (the minimum observed value was -0.00096ppm) and could not be modeled by an exponential decayfunction. These three negative emissions values were excludedfrom the PF control emission model.



### Page 8 of8