Post on 03-Oct-2021
Synthesis and Characterization of
Sucrose - Melamine - Formaldehyde Adhesive
Professor: Weixing Gan
Gangxi University, China
Outlet
Acknowledgments & Next work
Conclusions
Results and discussion
Materials and Methods
Background
SMF
Background
MF is common adhesive used in wood industries
(paper laminates); maybe replace of PF . Advantages:
high bonding strength, good boiling-water resistance and
low curing temperature ; Defects: the short shelf-life and
higher cost than UF ; Therefore, MF is modified .
Sucrose is a renewable, biodegradable, abundant with
low cost, and readily available. It is a good modifier for
MF because of rich hydroxyl groups (hydroxymethyl
groups specially).
The objective of this paper is to
investigate the synthesis process on
the sucrose modified MF (SMF)
resin, and to evaluate the
performance of the SMF resin as
affected by the sucrose content.
Background
Materials and Methods
Sucrose, Melamine and Formaldehyde
Characterizations of FT-IR and MS
Bonding Strength Test
Shelf-Life of Adhesive
Formaldehyde Emission
Materials and Methods
The preparation of the SMF resin
178 g of formaldehyde solution (37% wt %) and 1.3 g of
borax (0.3 wt %) were put into a reactor. The pH of
mixture was adjusted to 8.5 by sodium hydroxide
solution (0.1 mol/L). Then, 126 g of melamine and 138 g
of sucrose were added into the mixture. The temperature
was increased to 90℃, and kept for 150 min. When
water tolerance was 2 ,the solution was cooled to room
temperature and 192 g of water was added. Finally,
sodium hydroxide solution (0.1mol/L) was added to
adjust the pH to 7.5-8.5.
Results and Discussion
1.Fourier Transform-Infrared Spectroscopy Analysis
4000 3500 3000 2500 2000 1500 1000 50084
86
88
90
92
94
96
98
100
T/%
Wavenumbers/cm-1
MF
SMF
the SMF shows enhanced characteristic peaks at
3349cm-1 and 1160cm-1, compared to MF, indicating
the effect of sucrose groups on the structure of SMF
resin.
Fig. 1
2. Mass Spectrum Analysis
LCW-HZF-SMF # 92-96 RT: 2.56-2.67 AV: 5 SB: 8 2.26-2.45 NL: 3.30E6
T: - c Full ms [ 50.00-2000.00]
150 200 250 300 350 400 450 500 550 600 650 700 750 800
m/z
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
377.2
379.2
719.0
455.0
720.9404.1
215.2421.2
332.8176.0 264.1 278.1506.1 676.7590.5524.7
367.1 668.4 722.1621.8486.1 576.4 770.3
Fig. 2
Results and Discussion
O
HO O
OHHO
HOH2COH
CH2OH
HOH2C
OH
OH
O
The fragment from 719(m/z) to 377(m/z)
NH2
H2N NH2
The fragment from 234(m/z) to 108(m/z)
NH2
H2N NH
The fragment from 206(m/z) to 79(m/z)
N N
N
N
N
N
H2N
NH2
NH
NH
H2N
NH2
H2C
The fragment from 719 (m/z) to 455 (m/z)
O
HO
OHHO
-OH2CCH2O-
OH
O
HOH2C
OH
OH
O
The fragment from 719(m/z) to 379(m/z)
N
NN
NH
NH2
NH2
H2C
The fragment from 218 (m/z) to 79(m/z)
Fig. 3
Results and Discussion
The above analysis suggested that the SMF resin was
synthesized by the chemical condensation of melamine,
formaldehyde and sucrose. In addition, the main
covalent linkages between the monomers were ether
group and methylene group.
Results and Discussion
3. Bonding Strength Test
Fig. 4
Results and Discussion
Wood Failure Percentage (%) of SMF bonded Plywood in Bonding Strength Test
Mole ratio of S/M
0 0.2 0.4 0.6 0.8
F/M
1.8 80 60 60 30 10
2.0 80 50 60 40 10
2.2 100 80 70 40 20
The mole ratio of F/M is 1.8, 2.0, 2.2 and the wood failure
percentage is speculated according to Chinese standard of GB/T
17657-2013.
Results and Discussion
The bonding strength of the resins was reduced. As the S/M
ratio increases, the bonding strength of plywood decreases. A
turning point which meet the requirement of Chinese
standard of GB/T 17657-2013 (≥0.7MPa) of 0.4 S/M mole
ratio, 0.80 MPa, 0.86 MPa and 0.90 MPa, is shown in Fig. 4.
The incorporation of sucrose reduced the water resistant
(especially in boiling water) of the resin because of the
hydroxyl group of sucrose.
Results and Discussion
4. Shelf-Life test
0.0 0.2 0.4 0.6 0.80
10
20
30
40
50
60
70
80
90S
hel
f-li
fe/d
Mole Ratio of S/M
F/M=2.0
Fig. 5
Results and Discussion
0.0 0.2 0.4 0.6 0.80
10
20
30
40
50
60
70
80
90
Sh
elf-
life
/d
Mole Ratio of S/M
F/M=2.0
As the sucrose content increases, the shelf life increases
when the mole ratio of sucrose and melamine is
between 0 and 0.6. The longer shelf life of SMF may be
due to the efficient reaction of hydroxyl of sucrose and
the active groups-methylol of resin, so that the
crosslinking reaction of active groups of resin is
reduced.
Results and Discussion
5. Formaldehyde Emission test
0.0 0.2 0.4 0.6 0.80.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00F
orm
ald
ehy
de
Em
issi
on
/mg/L
Mole Ratio of S/M
F/M=2.0
F/M=1.8
Fig. 6
Results and Discussion
It is shown that different trends on the formaldehyde
emission vs. S/M ratios between the F/M 2.0 and F/M 1.8.
For the both F/M ratios, when the S/M ratio bellows 0.4,
increasing the sucrose content is beneficial to reducing
the formaldehyde emission. As the sucrose content
continues to increase, the formaldehyde emission
increases.
Results and Discussion
0.0 0.2 0.4 0.6 0.80.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
Fo
rmal
deh
yd
e E
mis
sio
n/m
g/L
Mole Ratio of S/M
F/M=2.0
F/M=1.8
It is equivalent to acknowledge an efficient reaction can be
coming true as the mole ratio of sucrose and melamine, 0.4.
Increased sucrose content could promote reaction of MF
resin and sucrose which will enhance the stability of chemical
bond of SMF resin to reduce the formaldehyde emission from
the degradation of ether.
Results and Discussion
A SMF adhesive that can be used indoor was synthesized by
the condensation of sucrose, melamine and formaldehyde.
An optimum sucrose to melamine mole ratio was found as
0.4:1, with a wet bonding strength of 0.90 MPa, formaldehyde
emission of 0.49 mg/L.
Compared with the MF adhesive, an improved performance
of shelf life was achieved.
SMF adhesives can be a potential alternative for environment-
friendly wood adhesive.
Conclusions
This work was financially supported by Natural Science
Foundation of China ( 31360158 ) , National Forestry
Industry Research Special Funds for Public Welfare
Projects(201004070) and Scientific and Technological
Development Projects of Guangxi Province(10100022-26,
1298025-11).
Acknowledgments
Investigating the synthesis mechanism of SMF resin by
building kinetic model of synthesis process
Investigating thermostability of SMF resin
Investigating the curing kinetics of SMF resin
Researching MMF (Maltose-Melamine-Formaldehyde) resin
Next work
蔗糖(左) 和麦芽糖(右)结构式The Structure of sucrose (left)and maltose (right)
2015-6-8