|Título/s:||Rheological behavior of an environmentally friendly dry blood powder based adhesive for the wood industry|
|Autor/es:||Bacigalupe, Alejandro; Garcia, Daniela Belén; Ferré, Omar|
|Institución:||INTI-Caucho. Buenos Aires, AR|
|Editor:||Nordic Rheology Society|
|Palabras clave:||Adhesivos; Adhesión; Propiedades reológicas; Industria maderera; Maderas; Industria alimentaria; Residuos; Polvo; Sangre; Composición química; Viscosidad|
| Ver+/- |
ANNUAL TRANSACTIONS OF THE NORDIC RHEOLOGY SOCIETY, VOL. 21, 2013
The aim of this paper is to study the
rheological behavior of an environmentally
friendly adhesive based on a secondary
product of food industry, dry blood powder
(DBP), to replace formaldehyde-based
adhesive such as urea-formaldehyde (UF)
resins in the production of wood
composites, increasing the added value of
the raw material.
Petroleum-based adhesives like UF are
widely used in plywood, composite wood
panels and furniture because of high
adhesion strength and low cost. This
adhesive has replaced historic based protein
products such as casein or blood, which
were displaced from the market.
However, highly toxic formaldehyde is
emitted during the production and post
production process. It is important to notice
that formaldehyde was declared a
carcinogen by the World Health
Organization (WHO) in 2004.1 Besides, the
future shortage of petrochemical-based
products supposes a rise in relative price and
lack of availability, leading on an increase in
the development of “green” products from
inexpensive and renewable resources. We
decided to work with DBP, which is a
secondary product of food industry and easy
to get in our country.
Blood consist of plasma, cell fraction
and fibrillar fraction. Plasma contains
different substances like lipoprotein,
fatty acids, sugars, soluble
proteins (albumins and globulins) and
mineral salts. The cell fraction (erythrocytes,
leukocytes and platelets) is rich
in hemoglobin. DBP is rich in proteins (see
Table 1), complex macromolecules and
contain a number of chemically linked
amino acid monomers, which form
polypeptide chains and constitute the
primary structure. These structural features
can be changed by physical, chemical or
enzymatic treatments. Such treatments alter
secondary, tertiary and quaternary structures
of the proteins without breaking the covalent
bonds and lead to protein denaturalization. It
is well known that the native structure of
protein can be modified to increase the
bonding strength of protein based adhesives.
Unfolded protein molecules have increased
surface area and hence afford improved
interaction with substrates.
Table 1. Chemical composition of DBP.
Fat Moisture 1
Rheological Behavior of an Environmentally Friendly Dry Blood Powder Based
Adhesive for the Wood Industry
Alejandro Bacigalupe1, Daniela Belén Garcia1, and Omar Ferré1
1 Instituto Nacional de Tecnología Industrial, Buenos Aires, Argentina
MATERIALS AND EQUIPMENT
DBP was provided by Willmor S.A.
The Merck p.a. sodium hydroxide
(NaOH) was purchased.
As antifoam the TEGO Foamex 1488
was used, provided by INTI-Procesos
For the UF adhesive the Coladur Plus by
Jucarbe was used.
Industrial stirrer DALV-50 with 0.5 HP.
Anton Paar Rheometer Physica MCR
301 with Concentric Cone of 27 mm
Hydraulic press Luis Santin model 100T
INSTRON 4467 Dynamometer, with 30
kN charge cell.
Skeist2 stated that all the protein based
adhesives present a non-Newtonian flow,
viscosity decreases with the increasing
sliding speed (Shear Thinning).
Therefore, the mechanism for the
measurement must cover all the ranges of
viscosities without any change in the slip
speed. The range of viscosity values have
been suggested for different applications by
Kumar et al.3 For absorbent adhesives the
viscosity is between 100 to 150 mPa.s (cP)
which is the value of a 50% UF adhesive
currently used by the local industry.
Adhesion depends on the ability of protein
to be dispersed in water and the interactions
with the substrate (wood). Stefani et al.4
indicates the dispersion is achieved through
the use of chemical agents that break the
secondary proteins structure (denature).
These include surfactants, urea and NaOH.
Different adhesives were prepared
varying DBP concentration from 20 to 40%
increasing in 5% at constant alkali
concentration of 0.025% by weight, and
compared to UF 50% adhesive.
All adhesives were analyzed in a
Rheometer with a rotational viscosity curve
at 25 ºC. The initial speed was 0,001 s-1 and
it was gradually increased to 4000 s-1. A
Concentric Cone of 27 mm diameter
geometry (CC27) was used for the
measurement. Results were shown in a
viscosity versus share rate diagram.
Shear strength adhesion determination
Five replications with pine wood were
prepared with the adhesives used for
viscosity determination. The samples were
applied in a hydraulic press, according to
standard specifications5, at 70 ºC for 60
minutes and 3 MPa of pressure. Finally,
samples were removed from press and
stabilized for 2 days at 23 ºC ± 2 ºC and 50
± 2% humidity. The adhesive weight applied
was 400 g/m2. Adhesion was register as
tension in MPa and plotted as tension versus
Pot Life Determination
The optimal DBP adhesive, obtained
with the Viscosity Determination was
prepared and analyzed as same conditions.
Viscosity was measured in the Rheometer
over 0, 7 and 14 days (DBP D0, DBP D7,
and DBP D14) and compared with UF 50%.
Results were presented as viscosity versus
Five replications with pine wood for the
three samples were applied and measured at
same conditions that the Shear strength
adhesion determination. Results were
presented as tension versus time.
Although viscosity at a low shear rate
(steady behaviour) is very different between
UF and DBP adhesives, at high shear rate
(application condition) the adhesives have
similar behaviour. DBP 35% present similar
viscosity than UF 50% and therefore, same
properties during application conditions
with spray (see Fig. 1).
It was shown by Lin and Gunasekaran6
that at low shear rate, high molecular weight
protein chains experience Brownian motion.
As the shear rate sufficiently increases to
overcome the Brownian motion, the proteins
chains become more ordered along the flow
field and offer less resistance to flow and
Figure 1. Viscosity curve for UF 50%
and DBP adhesives.
Shear strength adhesion determination
All Samples present useful adhesion
values although with high dispersion; this is
an expected behavior when we used natural
raw materials (see Fig. 2). Considering
adhesion values and that all the samples
presented cohesive failure it was decided to
work with the adhesive chosen by Viscosity
Figure 2. Adhesion of DBP adhesives.
Pot Life Determination
The DBP 35% adhesive was used for
this determination (see Table 2) and
measured as DBP D0.
All three samples show acceptable
adhesion values and wood cohesive failure
(see Fig. 3). DBP D7 presents very low
viscosity variation and still is an adhesive
with desirable rheological behaviour. DBP
D14 shows a significant decrease of the
viscosity due to alkali reactions which leads
to shorter protein chains, leading to an
excessive and undesirable water absorption
which would make difficult the application
process (see Fig. 4).
Table 2. Adhesive formulation with 35%
NaOH 0,5% 5.0
1.0E‐05 1.0E‐04 1.0E‐03 1.0E‐02 1.0E‐01 1.0E+00 1.0E+01 1.0E+02
Shear Rate [1/s]
15 25 35 45
Figure 3. Adhesion versus time for 35%
Figure 4. Viscosity curve of DBP at 0, 7 and
Trough this work, we optimize the DBP
percentage in the adhesive formulation,
based on their viscosity compared with UF
adhesives at application conditions.
The adhesion test allows us to conclude
that all the percentages studied present
cohesive failure of wood specimens; giving
a high performance adhesive for wood
Finally, the pot life determination shows
a slight increase in shear strength adhesion
within the desired values, but with
significant decrease in viscosity, making
difficult the application process. Based on
the properties analyzed, it was concluded
that the useful life of the adhesive is less
than 7 days of formulated process.
The viscosity, shear strength adhesion
and pot life determination allows us to
obtain a zero-emission formaldehyde
adhesive as a renewable and
environmentally friendly alternative for
1. International Agency for Research on
Cancer (2004). Press release # 153.
2. Skeist, I. (1989), “Handbook of
Adhesives”, Springer, pp. 163-173.
3. Kumar, R. Choudhary, V. Mishra, S.
Varma, I.K. Mattiason, B. (2002),
“Adhesives and plastics based on soy
protein products” Ind. Crops Prod., 18, 155-
4. Stefani, P.M. Leiva, P. Ciannamea, E.
Ruseckaite, R. (2006) “Aplicación de
Adhesivos de Soja para Aglomerados”
5. IRAM 45054, Adhesivos para estructuras
de madera bajo carga.
6. Lin, H. and Gunasekaran, S. (2010),
“Cow blood adhesive: Characterization of
physicochemical and adhesion properties”
International Journal of Adhesion &
Adhesives, 30, 139-144.
3.420 3.947 4.1720.000
0 7 14
1.0E‐03 1.0E‐02 1.0E‐01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04
Shear Rate [1/s]