ORIGINALS ORIGINALARBEITEN

VOC sorption and diffusion behavior of building materials

Sabrina Niedermayer • Christina Furhapper •

Stefan Nagl • Sylvia Polleres • Klaus Peter Schober

Received: 16 October 2012 / Published online: 18 June 2013

� Springer-Verlag Berlin Heidelberg 2013

Abstract In this study 25 different building materials

often used in timber constructions (wood based panels,

gypsum boards, vapor barriers, adhesive tapes, insulation

materials and sealants) were investigated with regard to

their adsorption, desorption and diffusion behaviour

towards volatile organic compounds (VOC). The materials

were exposed to four, respectively five selected VOCs

typically found in indoor air: hexanal, butyl acetate,

p-xylene, nonane and a-pinene. Adsorption and desorption

properties were investigated under static conditions,

whereas the diffusion behavior was examined in a

0.225 m3 emission chamber with an air exchange rate of

1 h-1. The results of the experiments indicate that some

building products have a high potential to reduce VOCs in

indoor air. Apart from the vapor barriers, two insulating

materials and one plasterboard, all tested materials repre-

sented an adsorption efficiency of about 50 % or higher

related to the injected VOC standards. Materials with high

adsorption capacity bound substances strongly and des-

orbed them less, whereas less adsorbing materials acted

inversely. The obtained results indicate that material

properties and processing play a considerable role in dif-

fusion behavior of building materials.

VOC-Sorptions- und Diffusionsverhalten von

Baumaterialien

Zusammenfassung In dieser Arbeit wurden 25 versch-

iedene Baumaterialien, die haufig Anwendung im Holzbau

finden (Holzwerkstoffe, Gipsplatten, Dampfbremsen, Kle-

bebander, Isolier- und Dichtungsmaterialien), hinsichtlich

ihres Adsorptions-, Desorptions- sowie Diffusionsverhal-

tens gegenuber fluchtigen organischen Verbindungen

(VOCs) untersucht. Dazu wurden die Materialien vier bzw.

funf, haufig in der Innenraumluft vorkommenden VOCs

ausgesetzt: Hexanal, Butylacetat, p-Xylol, Nonan und

a-Pinen. Die Adsorptions- und Desorptionsversuche

wurden unter statischen Bedingungen durchgefuhrt. Zur

Untersuchung des Diffusionsverhaltens wurden 0,225 m2

Emissionskammern mit einem Luftwechsel von 1 h-1

herangezogen. Die Ergebnisse der Untersuchungen zeigen,

dass einige Bauprodukte einen erheblichen Beitrag zur

Reduktion von VOCs in der Innenraumluft leisten konnen.

Mit Ausnahme der Dampfbremsen, zweier Dammstoffe

sowie einer Gipskartonplatte adsorbierten alle getesteten

Materialien mindestens 50 % der injizierten VOC-Stan-

dards. Materialien mit hoherem Adsorptionsvermogen

wiesen eine geringere Tendenz zur Desorption auf und

umgekehrt. Es zeigte sich, dass Materialeigenschaften so-

wie Verarbeitung eine nicht zu vernachlassigende Rolle

beim Diffusionsverhalten von Baumaterialien spielen.

1 Introduction

Since people in industrial countries stay up to 90 % of their

live indoors, air quality inside buildings plays an important

role in the well-being and health (Hoppe and Martinac

1998; Molhave et al. 1997). Pollutants, especially so-called

S. Niedermayer (&) � C. Furhapper (&)

Department of Chemistry, Holzforschung Austria,

Vienna, Austria

e-mail: s.niedermayer@holzforschung.at

C. Furhapper

e-mail: c.fuerhapper@holzforschung.at

S. Nagl � S. Polleres � K. P. Schober

Department of Structural Engineering, Holzforschung Austria,

Vienna, Austria

123

Eur. J. Wood Prod. (2013) 71:563–571

DOI 10.1007/s00107-013-0713-4

volatile organic compounds (VOCs), can be emitted from

building materials, interior furnishings, cleaning agents,

cigarettes or other sources (Meininghaus et al. 1999).

Energy efficient and airtight construction can induce

accumulation of these substances, which can provoke

health problems on inhabitants like irritation of eyes, nose

and throat. Symptoms like that are often summarized as

Sick-Building-Syndrome (SBS) (Barry and Corneau 2006;

Molhave et al. 1997). Selecting adequate low-emitting

building materials and high ventilation rates can reduce

VOC concentration in indoor air. Furthermore, it is known

that various materials show significant sink effects by

capturing VOCs and re-emitting them at a later stage (Seo

et al. 2009; van der Wal et al. 1998).

VOC emissions from building materials and especially

wooden products were studied by various authors (Chi-Chi

et al. 2009; Yu and Kim 2012). Sorption and diffusion

behavior of selected building materials, like gypsum boards,

carpets, floorings etc. are described in literature (Jorgensen

and Bjorseth 1999; Won et al. 2001; van der Wal et al. 1998),

whereas wood based panels like oriented strand board (OSB)

or particleboards were not analyzed in this context.

Due to their inherent VOC emissions wooden products are

often viewed critically in connection to indoor air quality.

In this study the adsorption and desorption behavior of

wood was investigated and compared to other building

materials used in timber constructions. The study was

aimed at evaluating whether wooden building materials can

contribute to a VOC reduction in indoor air.

Furthermore, the diffusion properties of different

building materials were determined in order to proof their

permeability for VOCs. The results enables predictions of

sink or barrier effects of the tested materials and conse-

quently of their influence on indoor air quality.

2 Materials and methods

2.1 Materials

In this study 25 building materials of different product

groups and manufacturers were included. They are listed in

Table 1. The Table also states important material proper-

ties like thickness, density, sd-/l-value and mass per unit.

The diffusion-equivalent air-layer-thickness (=sd-value)

is usually used for vapor barriers. It is defined as the

resistance which a building component layer opposes to

water vapor diffusion.

The l-value represents the water vapor diffusion resis-

tance factor (non-dimensional) which is the quotient of

sd-value and thickness of a material.

The samples were stored in non-emitting and airproof

aluminum bags at controlled conditions (23 �C, 50 %

relative humidity—RH) from the time of receipt from the

manufacturers until analysis.

For the determination of adsorption and desorption

behavior samples were cut to 8 9 15 cm (0.024 m2)

specimens, the cutting edges were sealed with non-emitting

aluminum adhesive tape.

For the diffusion experiments specimens of 30 9 30 cm

(0.09 m2) were prepared and their edges were sealed with

the tape as well.

All experiments were carried out as single deter-

minations.

2.2 Adsorption and desorption behavior

The investigation of adsorption and desorption behavior

was carried out by exposing the samples in containers to a

certain mixture of VOCs. Changes in the concentration of

the added compounds allow conclusions about adsorption

and desorption behavior of the tested materials to the

selected substances.

The samples (one specimen of each building material)

were placed into glass containers with a volume of

0.0034 m3 and covered with an aluminum lid. The lid was

furnished with two twist caps with septa for injecting the

standard solution and for air sampling. All tests were per-

formed under static conditions without any air exchange.

Two empty containers served as a reference.

Reference and testing containers were stored at 20 �C.

Before the mixture of VOCs was injected, a blank sample

was drawn in order to detect background emissions of the

samples. Afterwards 250 ll of a standard solution con-

taining typical representatives of indoor air pollutants

(hexanal, butyl acetate, p-xylene and a-pinene in methanol)

were injected (t = 0 h).

The comparatively high concentration of the standard

solution (10 mg/ml) was chosen to simulate a worst-case

scenario and to detect possible effects more clearly. Every

24 h (until 168 h) an air sample was drawn manually with

a Hamilton syringe and injected into the gas chromatog-

raphy-mass spectrometry (GC/MS) system (Agilent GC

6890N, Agilent MSD 5973). The GC-column of choice

was a HP5-MS UI (60 m 9 0.25 mm 9 0.25 lm). The

following GC temperature program was applied for anal-

ysis: start temperature at 40 �C, 10 �C/min until 100 �C

and 25 �C/min until 300 �C. For MS the following

parameters were chosen: SCAN mode, mass from 40 to

300 and analysis via target and qualifying ions and total ion

current (TIC).

Qualitative analysis was carried out via comparison of

the specific mass spectra with commercial spectra libraries

and the retention times of the standards substances. Semi-

quantitative analysis was performed by comparing the peak

areas of the samples with the references.

564 Eur. J. Wood Prod. (2013) 71:563–571

123

It was assumed that the reference glass containers con-

tain 100 % of the injected VOCs in the gas phase, because

sink effects from containers, lids etc. are the same for

containers with and without sample. Adsorption by sam-

ples will result in lower concentrations of VOCs in the gas

phase.

After termination of the adsorption experiments, the

same samples were subjected to desorption experiments in

order to investigate the relative release of the previously

adsorbed VOCs.

Therefore samples were transferred into cleaned glass

containers and stored for 24 h at 20 �C, 24 h at 30 �C and

24 h at 40 �C. Air samplings took place after 24 h at each

temperature and were carried out by analogy to the

adsorption tests, as well as the qualitative and semi-quan-

titative analyses.

It was assumed that the concentration value of VOCs

adsorbed from a sample is the maximum value (100 %)

which a sample can desorb—material inherent emissions

excluded.

2.3 Diffusion behavior

Investigation of the diffusion behavior should provide

information about permeability of the building materials

regarding VOCs.

Samples (one specimen of each building material) were

taped with non-emitting aluminum adhesive tape onto

square glass boxes (volume 0.0069 m3) containing an inlet

for injecting the standard solution. The boxes were put into

0.225 m3 emission chambers under controlled climatic

conditions (23 ± 1 �C, 50 ± 3 % RH, air exchange rate

1 h-1) and conditioned for 24 h.

In order to determine material emissions, blank air

samples were drawn before 250 ll of the standard solution,

consisting of hexanal, butyl acetate, p-xylene, a-pinene and

Table 1 Tested materials and material properties

Tab. 1 Untersuchte Materialien und Materialeigenschaften

Product

groups

Samples Base Thickness

(mm)

Density

(kg/m3)

sd-*/l-

value (m)

Mass per unit

area (g/m2)

Wood based

panels

Medium density fiberboard

(MDF)

Fiberboard, PMDI binder 13.0 640.9 11 –

Oriented strand board (OSB) 1 Oriented strand board, PMDI binder 15.0 600.2 200 –

Oriented strand board (OSB) 2 Oriented strand board, PMDI binder 15.0 602.7 200 –

Oriented strand board (OSB) 3 Oriented strand board, PMDI binder 14.5 583.2 200 –

Particleboard 1 Particleboard, UF binder 19.0 680.5 50–100 –

Particleboard 2 Particleboard, PMDI binder 16.0 682.2 50–100 –

Particleboard 3 Particleboard, PMDI binder 16.0 667.8 50–100 –

3-layer-board Multilayer board, spruce, MUF

binder

19.0 469.5 50 –

Gypsum

boards

Gypsum fiberboard 1 Gypsum fiberboard 12.5 1328.4 21 –

Gypsum fiberboard 2 Gypsum fiberboard 10.0 1153.7 21 –

Plasterboard 1 Plasterboard 12.5 835.8 10 –

Plasterboard 2 Plasterboard 12.5 755.0 10 –

Plasterboard 3 Plasterboard 12.5 829.2 10 –

Plasterboard 4 Plasterboard 12.5 712.1 10 –

Plasterboard 5 Plasterboard 18.0 888.9 10 –

Insulating

materials

Mineral wool Mineral wool, PF resin – – 1 –

Hemp fiber Hemp fiber 50.0 50.7 – –

Low density fiberboard Fiberboard, PUR binder 50.0 158.1 5 –

Vapor

barriers

Vapor barrier 1 Building paper – – 10.0* 100

Vapor barrier 2 Fleece with fabric insert – – 7.5* 85

Vapor barrier 3 Fleece – – 2.3* 185

Sealants Bitumen rubber Bitumen rubber – – 170.0* 1700

Adhesives Adhesive tape 1 Fleece – – – –

Adhesive tape 2 Fleece – – – –

Adhesive tape 3 PE-film – – – –

Eur. J. Wood Prod. (2013) 71:563–571 565

123

nonane, were injected (t = 0 h). The standard solution had

a comparatively high concentration of 10 mg/ml, for sim-

ulating a worst-case scenario as done before in the

adsorption/desorption experiments. Samples from the

emission chamber air were drawn after 1, 3, 24, 48 and

72 h for 1 h on Tenax TA� tubes with an air flow rate of

100 ml/min. The Tenax TA� tubes were analysed with

GC/MS (Agilent GC 6890N, Agilent MSD 5973) coupled

with a thermal desorption unit (Markes International

Limited, Unity Thermo desorption device with Ultra TD

autosampler). The operating parameters for the thermal

desorption device were: Desorption of the Tenax TA�

tubes for 5 min at 280 �C, cold trap for 5 min at -3 �C,

trap desorption with abrupt heating to 300 �C and split

ratio of 10:1. The GC–MS operating parameters were the

same as for the adsorption and desorption analyses.

In order to determine a possible diffusion through twist

caps and the plate-box-connection, reference experiments

were carried out. In these experiments a glass plate

substituted the specimen and the boxes were treated in the

same manner as the sample boxes (climatic conditions,

sampling etc.).

The results of these experiments allowed a rough com-

parison of the tested building materials regarding their diffu-

sion behavior. Nevertheless the total diffusion is always

affected by the adsorption ability of the material, which cannot

explicitly be excluded using this experimental setup.

The calibration included a large number of typical

building product related compounds such as alkanes,

aldehydes, ketones, terpenes and carboxylic acids. Stan-

dard stock solutions were prepared with a concentration of

1 mg/ml in methanol, diluted appropriately and directly

applied under a constant inert gas flow on the Tenax TA�

tubes. Cyclodecane was used as internal standard. The

standard tubes were analysed analogous to sample tubes by

thermal desorption and GC/MS.

Table 2 Adsorption/desorption behavior: Ranking of the tested building materials within their product groups

Tab. 2 Adsorptions-/Desorptionsverhalten: Rangfolge der untersuchten Baumaterialien innerhalb ihrer jeweiligen Produktgruppe

Materials Adsorption (%) Desorption cumulative (%)

20 �C 20 �C 30 �C 40 �C

TVOC 7 days TVOC 24 h TVOC 24 h TVOC 24 h

Wood based panels

MDF 82 6 11 16

OSB 1 72 17 33 47

OSB 3 61 33 46 64

OSB 2 55 25 45 55

Particleboard 1 67 16 31 33

Particleboard 2 49 20 37 47

Particleboard 3 47 21 49 38

3-layer-board 52 8 19 35

Gypsum boards

Gypsum fiberboard 2 69 13 20 30

Gypsum fiberboard 1 58 10 22 26

Plasterboard 5 65 6 23 43

Plasterboard 1 64 9 17 19

Plasterboard 3 60 15 27 37

Plasterboard 4 60 12 22 23

Plasterboard 2 41 20 34 29

Sealants

Bitumen rubber 68 11 12 23

Insulation materials

Low density fiberboard 74 7 16 19

Mineral wool 30 51 92 [100

Hemp fiber 26 98 81 [100

Vapor barriers

Vapor barrier 2 20 54 43 [100

Vapor barrier 1 9 80 91 [100

Vapor barrier 3 8 100 [100 [100

566 Eur. J. Wood Prod. (2013) 71:563–571

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Qualitative analysis was carried out via comparison of

the specific mass spectra with commercial spectra libraries

and via comparison of the retention times of the standards

substances.

Quantitative analysis was performed substance specifi-

cally via standard calibration curves. VOCs, which were

not included in the calibration or could not be identified,

were quantified via toluene d8 equivalents.

3 Results and discussion

3.1 Adsorption and desorption behavior

Table 2 shows a ranking of the tested building materials

within their product groups sorted from the highest to the

lowest adsorbed amount of injected VOC standard solu-

tion. The adsorption results are mean values of the total

adsorption of all substances at 20 �C during 1 week

(168 h). Percentages of adsorbed VOCs of the samples

refer to the reference container without a sample, which is

assumed to be 0 % (sink effect from equipment excluded)

and to the amount of VOCs injected (100 %). Furthermore,

values of the total desorption of all standard substances

after 24 h at 20 �C, 24 h at 30 �C and 24 h at 40 �C are

shown cumulatively. Percentages of desorbed VOCs refer

to the amount of VOCs that were adsorbed from the

samples. If the total desorption exceeds 100 % this is due

to additional material emissions.

It can be seen from the results that all tested materials,

apart from the vapor barriers, the mineral wool, the hemp

fiber and plasterboard 2, represented an adsorption effi-

ciency of about 50 % and higher. Furthermore the results

show that materials with a high adsorption capacity bind

substances strongly and desorb them less, whereas less

adsorbing materials act in an inverse manner.

Except for the vapor barrier 3, which already showed a

100 % desorption at the initial temperature of 20 �C,

desorption effects increased with elevated temperatures.

For the majority of the tested materials desorption was

highest at a temperature of 40 �C, exceptions were parti-

cleboard 3 and plasterboard 2. Despite intensive investi-

gations the reason for this divergence was not found.

During one week after standard injection at 20 �C the

medium density fiberboard (MDF) with its finely shredded

wood particles showed the strongest adsorption tendency of

the tested wood based panels, respectively of all tested

materials, whereas the 3-layer-board made of solid wood

belonged to the lower adsorbing wood based panels. The

gypsum boards showed similar values except for plaster-

board 2 which adsorbed less compared to the other sam-

ples. The insulation materials showed inconsistent results:

The low-density fiberboard with its large specific surface

presented rather high adsorption efficiency whereas the

mineral wool and the hemp fiber belonged to the less

adsorbing materials. The bitumen rubber (sealant) showed

an unexpectedly strong adsorption tendency. The vapor

barriers especially vapor barrier 1 and 3, barely showed

interaction with the injected VOCs, in contrast to the fiber

board materials they seemed to be limited by their small

specific surface. Adhesive tapes were not tested for their

sorption behavior.

Considering the desorption behavior of the wood based

panels, MDF showed the lowest release of the adsorbed

VOC substances. The oriented strand boards represented

much higher concentrations of the desorbed VOCs, which

is at least partly caused by inherent material emissions. In

comparison the particleboards released lower amounts of

the adsorbed VOCs, but they were also influenced by

intrinsic material emissions.

The 3-layer-board desorbed less at 20 �C but reached

the level of the particleboards at 40 �C.

All gypsum boards released less than 50 % of the

adsorbed VOCs. The two gypsum fiberboards represented a

similar behavior in the sorption experiments, whereas the

plasterboards did not show a comparable relation between

adsorption and desorption.

The bitumen rubber, unexpectedly strong adsorbing,

showed a very low desorption tendency. Regarding the

insulation materials, only the low-density fiberboard had

the potential of holding back adsorbed VOCs—also at

higher temperatures. Vapor barriers released the total

amount of adsorbed VOCs at the latest at 40 �C.

3.1.1 Adsorption behavior in detail

Figure 1 presents the adsorption behavior of the wood

based materials in detail. In the diagrams the residual

content of VOC in the gas phase [%] is plotted over the

elapsed time [h] after standard injection. Percentages of the

residual content of VOC in the gas phase of containers with

samples refer to the reference container without samples,

which is assumed to be 100 % (sink effects from equip-

ment excluded). After standard injection (0 h) the VOC

content in the gas phase decreased rapidly until 24 h and

remained approximately constant till the end of the

experiment (steady state). An exception was the 3-layer-

board, which showed a permanent decrease of the VOC

concentration until the end of the test.

Considering the adsorption behavior of wood based

panels regarding the four injected standard substances, the

MDF showed very strong adsorption efficiency towards

hexanal and butyl acetate, followed by p-xylene and a-

pinene. OSB 3 revealed a much stronger adsorption of

hexanal compared to the other substances, which were

adsorbed equally. Particleboard 3 indicated a higher

Eur. J. Wood Prod. (2013) 71:563–571 567

123

adsorption of hexanal and butyl acetate than of p-xylene

and a-pinene. Also the 3-layer- board represented a higher

adsorption tendency concerning hexanal and butyl acetate,

whereas p-xylene and a-pinene were adsorbed less.

The results indicate that smaller and more polar com-

pounds like hexanal and butyl acetate were adsorbed

preferably compared to sterically hindered and non-polar

compounds like a-pinene and p-xylene. Meininghaus et al.

(1999) presented similar results for gypsum boards. With

regard to a-pinene material intrinsic emissions from the

samples, especially from OSB, complicated the interpre-

tation of the results.

3.1.2 Desorption behavior in detail

Figure 2 shows the desorption behavior of the MDF, the

3-layer-board, one OSB as well as one particleboard in

detail. In the diagrams, the desorbed amount of VOC [%] is

plotted over the increasing temperature [�C]. Percentages

of desorbed VOCs refer to the amount of VOCs adsorbed

from the samples (the adsorption of each particular VOC

was used as a calculation base).

Concerning the desorption behavior of wood based

panels regarding the previously injected and adsorbed VOC

standards, the MDF desorbed less than all other materials.

It showed the highest desorption for a-pinene and p-xylene,

followed by butyl acetate and hexanal.

OSB 3 desorbed high concentrations of hexanal and a-

pinene, at 40 �C almost 100 %, which was probably not

only caused by desorption, but by inherent material emis-

sions too. Particleboard 3 mostly released a-pinene and p-

xylene. The 3-layer-board desorbed high concentrations of

a-pinene, followed by p-xylene. Hexanal and butyl acetate

were desorbed to an equally low extent.

3.2 Diffusion behavior

Table 3 presents a ranking of the tested building materials

within their product groups sorted from the lowest to the

highest total amount of five injected VOC standards that

Fig. 1 Adsorption behavior of a MDF, b OSB 3, c particleboard 3 and d 3-layer board within 168 h after standard injection (white square:

hexanal, black circle: butyl acetate, white diamond: p-xylene and black triangle: a-pinene)

Abb. 1 Adsorptionsverhalten von a MDF, b OSB 3, c Spanplatte 3 und d 3-Schichtplatte innerhalb von 168 h nach Standard-Injektion (Weißes

Quadrat: Hexanal, schwarzer Kreis: Butylacetat, weißer Diamant: p-Xylol und schwarzes Dreieck: a -Pinen)

568 Eur. J. Wood Prod. (2013) 71:563–571

123

diffused (out of the glass boxes) through the samples. The

experiments were carried out for 72 h, but it was shown

that the strongest diffusion takes place in the first couple of

hours after VOC standard injection. The first column listing

the blanks shows the material inherent emissions of the

samples. As can be seen, the interpretation of the data for

the OSB samples is complicated due to significant material

emissions.

The MDF-sample showed the highest and the 3-layer-

board the lowest permeability among the tested wood

based panels. These samples showed an inverse behavior in

sorption and diffusion experiments. A stronger barrier

effect of the materials arises most likely from material

properties (high thickness, high density and low porosity)

as well as from the type of processing (particle size).

Concerning the gypsum boards gypsum fiberboard 1 and

plasterboard 5 were least whereas plasterboard 4 was by far

highest permeable.

The three vapor barriers showed very different effi-

ciency in retaining the injected VOC standards. Vapor

barrier 3 had the strongest barrier effect towards VOC,

whereas vapor barrier 1 and 2 represented a much lower

barrier effect whereby the obtained results showed a good

relation with their mass per unit area but not with their SD-

values (see Table 1). The bitumen rubber showed very low

permeability for the injected VOCs, which can be

explained by its high sd-value and mass per unit. From the

different adhesive tapes tape 1 showed the lowest and tape

2 the highest permeability. Insulation materials were

excluded from the diffusion tests, because experimental

setups were not suitable for these samples.

Figure 3 presents the diffusion pattern of the five

injected standards through the MDF, the 3-layer-board, one

OSB and one particleboard. The diffused amounts of VOC

[mg/m3] are plotted over the elapsed time [h] after standard

injection. The curves in the diagrams show that the main

diffusion through the permeable samples takes place 1 and

3 h after standard injection, whereas semi- and non-per-

meable samples represented a constant barrier effect until

the end of the experiments.

Considering the diffusion pattern of the five injected

standard substances for wood based panels in detail, MDF

showed high permeability towards butyl acetate, p-xylene

and nonane, whereas hexanal and a-pinene were retained to

Fig. 2 Desorption behavior of a MDF, b OSB 3, c particleboard 3 and d 3-layer board regarding the injected standard substances at 20, 30 and

40 �C (black column: hexanal, dark grey column: butyl acetate, light grey column: p-xylene, white column: a-pinene)

Abb. 2 Desorptionsverhalten von a MDF, b OSB 3, c Spanplatte 3 und d 3-Schichtplatte in Bezug auf die injizierten Standardsubstanzen bei 20

30 und 40 �C (schwarze Saule: Hexanal, dunkelgraue Saule: Butylacetat, hellgraue Saule: p-Xylol, weiße Saule: a -Pinen)

Eur. J. Wood Prod. (2013) 71:563–571 569

123

a larger extent. The box with OSB 3 represented a higher

concentration of hexanal, which did mainly result from

inherent VOC emissions of the sample (see blank in

Table 3, high concentration of a-pinene and hexanal were

found already before standard injection). Diffusion of

a-pinene and hexanal through particleboard 3 tended to be

lower than diffusion of the other standard substances. The

3-layer-board showed a strong barrier effect against all five

tested standard substances.

3.3 Comparing sorption with diffusion behaviour

It was observed that sorption as well as diffusion behavior

of materials within a product group, with a few exceptions,

are located in the same range and relate to each other, this

is especially true for particle- and plasterboards.

The results of the oriented strand boards were signifi-

cantly influenced by material inherent emissions, therefore

a correlation between adsorption and diffusion behavior

could not be found. The MDF represented the highest

adsorption efficiency, but a very low barrier effect against

VOCs was observed. The 3-layer-board was one of the less

adsorbing materials but indicated a strong barrier effect.

The barrier effect of materials is most likely mainly

dependent on material properties (thickness, density and

porosity) as well as on the type of processing (particle

size).

The gypsum fiberboard 2 adsorbed more than gypsum

fiberboard 1, but VOCs diffused more through gypsum

fiberboard 2. It can be assumed that thickness and porosity

had the largest influence. The bitumen rubber represented a

strong adsorption as well as a strong barrier effect. The

latter was expected because of its high sd-value and mass

per unit.

The vapor barriers showed only slight adsorption effi-

ciency due to their small specific surface, and in addition,

vapor barrier 1 and 2 indicated a high permeability for

VOCs. Only vapor barrier 3 showed a stronger barrier

effect. The results of the diffusion experiments presented a

relation with the mass per unit area, but not with sd-values,

although Xu et al. (2009) described the similarity of dif-

fusion kinetics between moisture and VOC for a gypsum

board and an oriented strand board.

4 Conclusion

Herein, methods were developed to gather basic informa-

tion concerning the adsorption, desorption and diffusion

behavior of building materials related to VOCs.

All 25 materials tested, apart from the vapor barriers,

two insulating materials and one of the plasterboards,

represented an adsorption efficiency of about 50 % and

higher. Materials with a high adsorption capacity bound

substances strongly and desorbed them less, whereas

weaker adsorbing materials acted inversely. Smaller and

more polar compounds, like hexanal and butyl acetate,

were preferably adsorbed compared to bulky and non-polar

compounds, like a-pinene and p-xylene. Especially with

regard to a-pinene, however, material inherent emissions

from the wooden samples play an important role as they

interfere with sorption processes.

It could be seen that sorption as well as diffusion

behavior of materials within a product group, with a few

exceptions, is located in the same range and relates with

each other.

Although wood based materials due to their emission

behavior are often criticized in context to indoor air

Table 3 Diffusion behavior: ranking of the tested building materials

according to product groups

Tab. 3 Diffusionsverhalten: Rangfolge der untersuchten Baumateri-

alien bezogen auf ihre Produktgruppen

Materials Diffusion (mg/m3)

Blank 1 h 3 hP

72 h

Wood based panels

MDF 0.00 5.47 4.76 12.76

OSB 3 0.37 0.50 1.16 3.12

OSB 1 0.90 0.66 0.93 3.59

OSB 2 0.24 0.75 1.92 3.58

Particleboard 1 0.01 0.61 1.81 3.12

Particleboard 2 0.02 1.06 2.61 4.30

Particleboard 3 0.01 1.80 3.15 5.31

3-Layer board 0.01 0.32 0.38 1.26

Gypsum boards

Gypsum fiberboard 1 0.01 3.74 2.69 6.69

Gypsum fiberboard 2 0.04 4.86 4.44 9.49

Plasterboard 5 0.01 5.86 0.12 6.50

Plasterboard 1 0.02 6.22 1.61 8.16

Plasterboard 2 0.01 6.50 1.76 8.41

Plasterboard 3 0.02 7.84 1.05 9.18

Plasterboard 4 0.02 13.81 5.5 19.69

Sealants

Bitumen rubber 0.01 0.07 0.03 0.17

Vapor barriers

Vapor barrier 3 0.01 0.45 0.76 2.10

Vapor barrier 1 0.01 4.13 3.18 7.77

Vapor barrier 2 0.01 8.03 3.81 12.02

Adhesive tapes

Adhesive tape 1 0.01 0.08 0.21 1.19

Adhesive tape 3 0.01 2.20 4.51 7.07

Adhesive tape 2 0.01 5.70 7.77 13.73

Reference 0.01 0.01 0.01 0.75

570 Eur. J. Wood Prod. (2013) 71:563–571

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quality, the gained results demonstrate their potential to

reduce VOCs in indoor air.

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Fig. 3 Diffusion behavior of a MDF, b OSB 3, c particleboard 3 and d 3-layer board towards injected standard substances in 72 h (white square:

hexanal, black circle butyl acetate, white diamond: p-xylene, black triangle: nonane and white triangle: a-pinene)

Abb. 3 Diffusionsverhalten von a MDF, b OSB 3, c Spanplatte 3 und d 3-Schichtplatte gegenuber der injizierten Standardsubstanzen innerhalb

von 72 h (weißes Quadrat: Hexanal, schwarzer Kreis: Butylacetat, weißer Diamant: p-Xylol, schwarzes Dreieck: Nonan und weißes Dreieck: a -

Pinen)

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