Synthesis, Thermal properties and nucleating effect of N, N, N, N′-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide as nucleating agent of poly(L-lactic acid)

Article abstract of DOI:10.1155/2012/645635

N, N, N, N′-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide as nucleating agent of Poly(L-lactic acid) (PLLA) was synthesized from benzoyl hydrazine and tetraacetic acid by acylation and ammoniation. and the structure of this novel tetraamide compound had been characterized by FT-IR. The thermal stability of N, N, N, N′-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide was investigated by TGA thermal analyzer. The result showed good thermal stability of N, N, N, N′-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide under 170°. N, N, N, N′-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide modified PLLA sample was prepared by a melt-mixing technique. With incorporation of 0.5% N, N, N, N'- Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide, Non-isothermal crystallization behavior at different cooling rate showed the crystallization peak of PLLA became sharper and shift to higher temperature, and indicated that the presence of N, N, N, N′-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide accelerated the overall PLLA crystallization.

Full text of DOI:10.1155/2012/645635

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
http://www.ejchem.net
2012, 9(3), 1575-1580
Synthesis, Thermal Properties and Nucleating Effect
of N, N, N, N'-Tetra(benzoyl) Ethylene Diamine
Tetraacetic Acid Dihydrazide as Nucleating Agent of
Poly(L-lactic acid)
YAN-HUA CAI
School of Materials and Chemical Engineering, Chongqing University of Arts and Sciences,
Yongchuan, Chongqing-402160, P.R. China
caiyh651@yahoo.com.cn
Received 4 October 2011; Accepted 3 December 2011
ABSTRACT: N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid
dihydrazide as nucleating agent of Poly(L-lactic acid) (PLLA) was synthesized
from benzoyl hydrazine and tetraacetic acid by acylation and ammoniation.
and the structure of this novel tetraamide compound had been characterized by
FT-IR. The thermal stability of N, N, N, N'-Tetra(benzoyl) ethylene diamine
tetraacetic acid dihydrazide was investigated by TGA thermal analyzer. The
result showed good thermal stability of N, N, N, N'-Tetra(benzoyl) ethylene
diamine tetraacetic acid dihydrazide under 170℃. N, N, N, N'-Tetra(benzoyl)
ethylene diamine tetraacetic acid dihydrazide modified PLLA sample was
prepared by a melt-mixing technique. With incorporation of 0.5% N, N, N, N'-
Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide, Non-isothermal
crystallization behavior at different cooling rate showed the crystallization
peak of PLLA became sharper and shift to higher temperature, and indicated
that the presence of N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic
acid dihydrazide accelerated the overall PLLA crystallization.
Keywords: Benzoyl hydrazine; Poly(L-lactic acid); Tetraacetic acid; Thermal stability;
Crystallization.
Introduction
Poly(L-lactic acid) is a very important gree polymer due to its low energy consumption,
biodegradable properties and non-toxic to the environment[1-5]. However, slow
crystallization rate of PLLA is too weak for practical application [6]. Thus, it is necessary to
increase crystallization rate of PLLA to make it fully competitive with commercial
thermoplastics. Now, the most viable method to increase the overall crystallization rate is
the blending with nucleating agent. It has been reported that amides could be used to
improve the crystallization rate of PLLA as nucleating agent [7]. For example, the
importance of the amides in PLLA has been recently highlighted in our previous paper [6].
In that paper, it is reported that 0.8%N,N'-bis(benzoyl) suberic acid dihydrazide make the
crystallization half-time of PLLA decrease from 26.5 min to 1.4 min at 115°C, and

1576 YAN-HUA CAI
nucleating mechanism belongs to the mechanisms of chemical. Finally, we presume that
hydrogen bonding come into being between PLLA and N,N'-bis(benzoyl) suberic acid
dihydrazide according to their functional groups analysis. Thus, in this paper, N, N, N, N'-
Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide including more amide
functional groups was synthesized to improve crystallization of Poly(L-lactic acid), and we
fabricated the PLLA/0.5%N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid
dihydrazide samples by melt-mixing technique. The thermal properties and nucleating effect
of N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide on PLLA was
investigated.
Experimental Section
Materials
The materials used in this study were of analytical grade (AR). Benzoyl hydrazine and
tetraacetic acid were procured from Chengdu Kelong Chemical Reagents Company (Sichuan
Province, China). Thionyl dichloride, N, N-dimethylacetamide and Pyridine were procured
from Mianyang Rongshen Chemical Reagents Company (Sichuan Province, China), Poly(L-
lactic acid) (PLLA) was purchased from Nature Works LLC, USA.
Synthesis procedure of N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid
dihydrazide (NA)
N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide was prepared as
shown in Scheme 1: tetraacetic acid, Thionyl dichloride of 60 mL in the presence of N, N-
dimethylacetamide as catalyst was mixed, and the mixture was heated up to 78°C, and held
at 78°C for 10 h with stirring. After cooling to room temperature and evaporation of thionyl
dichloride in vacuum, the residue was tetrachloride.
Benzoic hydrazide and N, N-dimethylacetamide of 70 mL were mixed, and the mixture was
purged under nitrogen atmosphere. Tetrachloride was added slowly onto the mixture,
followed by adding pyridine of 0.073 mol, and the mixture was heated up to 70°C, and held
at 70°C with stirring. Reaction mixture was poured onto water of 350 mL and stirred,
followed by filtrating. Obtained crude product was washed four times by water of each 350
mL at room temperature, and then washed by methanol of 250 mL at 50°C to eliminate raw
materials and by-products, the resulting product was dried in a vacuum at 60°C.
O
O
C
O
C
H2
C
H2
C
O
H2
C
H2
C
H2 H2
C
Cl
Cl
DMF
Cl
Cl
H2 H2
C C
N
OH
OH
HO C
SO2
HCl
+
+
N
C
C
N
SOCl2
+
N
C
H
C
2 O
C
C
C
H
C
2 O
HO
C
C
H2
H2
O
O
C O
D
NH
M
F
NH2
O
C
O
H2
O
O
C
H
N
H2
C
H
N
H
N
H
N
C
C
C
H2 H2
C C
N
N
H
N
H
N
H
N
H
N
C
O
C
C
C
H
C
2 O
C
O
H2
O
Scheme 1. Synthesis of N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide.

Synthesis, Thermal Properties and Nucleating Effect
1577
Preparation of PLLA/NA sample
PLLA was dried over night at 45°C under vacuum respectively to remove residual water.
Blending of PLLA and NA was performed on a counter-rotating mixer with a rotation speed
of 32 rpm for 4 min, then at 64 rpm for 4 min. The processing temperature was set at 175°C
but it increased to 180°C upon mixing. Products were hot pressed at 175°C under 20 MPa for
4 min to prepare sheets. The sheets were then cooled down by being compressed at room
temperature under 20 MPa for 10 min.
Characterization
Fourier transform infrared spectra were recorded on a Bio-Rad FTS135 spectrophoto-meter
from 4000 to 400 cm-1. The sample of NA was mixed with KBr powders and pressed into a
disk suitable for IR measurement.
The thermal stability of N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid
dihydrazide was measured by Thermogravimetric Analysis (TGA). TGA was performed
using a thermal analysis Q500 from TA Instruments-Waters LLC with a heating ramp of
20°C /min under air flow (60 ml/min) from room temperature to 450°C.
The nucleating effect of NA for PLLA was measured by Differential Scanning
Calorimeter (DSC). The PLLA and PLLA/0.5%NA samples were first heated to 190°C and
held at the same temperature for 5 min, then were cooled at a different cooling rate from
melt.
Results and discussion
Structures of NA
The FT-IR spectra of NA was shown in Fig.1. In the spectra, the peaks at 3420.2 cm-1 and
907.6 cm-1 contribute to the absorption of N-H stretching vibration and the plane bending
vibration, and the absorption peak at 1740.3 cm-1 contribute to C=O stretching vibration of
the amide group. Owing to conjugated effect between carbonyl and benzene, carbonyl
absorption move to lower frequency. Thus, the absorption peak at 1655.8 cm-1 contribute to
C=O stretching vibration of benzoyl hydrazine. Then the absorption peaks at 1577 cm-1,
1522.8 cm-1, 1482.5 cm-1 proved the existence of a benzene. The absorption peak at 1273.5
cm-1 was mixed peak including C-N stretching vibration and N-H bending vibration
absorption, the absorption peak at 1380.7 cm-1, 790.5 cm-1, 700.7 cm-1 belongs to C-H
stretching vibration. Infrared spectrum analysis showed N, N, N, N'-Tetra(benzoyl) ethylene
diamine tetraacetic acid dihydrazide had been synthesised.
Thermal properties of NA
Figure.2 shows the TGA curves of N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic
acid dihydrazide with a heating ramp of 1, 2.5, 5, 15, 20°C /min under nitrogen flow from
room temperature to 450°C. As seen in figure.2, N, N, N, N'-Tetra(benzoyl) ethylene
diamine tetraacetic acid dihydrazide begin to decomposition above 170°C, which can
suggest that N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide has
good thermal stability during application temperature of polymer. With the increasing of
heating rate, the decomposition temperature increases, the reason is that rapid heating rate
make decomposition of N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid
dihydrazide not achieve at set temperature, at the same time, the temperature has get into the
following set temperature, resulting in decomposition achieving at higher temperature. This
result is consistent with that of other decompositon compound [8-9].

1578 YAN-HUA CAI
Figure 1. The FTIR spectra of N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid
dihydrazide.
Figure 2. TGA curves of N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide.
Nucleating effect of NA
Non-isothermal crystallization behavior is of very practical interesting, This is because
polymers are usually processed under non-isothermal cycles. Figure 3 shows the DSC
curves of non-isothermal crystallization from melt at a different cooling rate. The
crystallization of neat PLLA is very slow. Upon cooling at 1°C/min, the crystallization peak
is not detected. With addition of 0.5%NA, crystallization peak appears in the DSC cooling
curve. Compared to the neat PLLA, NA made the melt crystallization peak of PLLA shift to
higher temperature, which indicated that NA could increase the crystallization temperature
of PLLA, On the other hand, NA made the melt crystallization peak becomes much sharper
in the cooling process, the result shown NA could increase the overall crystallization rate,
and serve as a nucleating agent for the crystallization of PLLA. As showed in Figure 3, the

Synthesis, Thermal Properties and Nucleating Effect
1579
melt crystallization peak of PLLA/0.5% NA shifts to lower temoerature and becomes wider
with increasing of cooling rate. Similar results can be found in other systems such as PLLA/
modified carbon black composites [10]. with the addition of 0.5% NA, the crystallization
temperature (To) increase from 105.88°C to 116.12°C, and the crystallization enthalpy(ΔHc)
increase from 1.379 J•g-1 to 41.41 J•g-1 at a cooling rate of 1°C/min from melt.
Figure 3. DSC of PLLA and PLLA/0.5%NA crystallized from melt at a different cooling rate.
Conclusions
N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide as nucleating
agent of PLLA was synthesized from benzoyl hydrazine and tetraacetic acid by acylation
and ammoniation. Investigations on the Thermal properties and nucleating effect of N,
N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide were carried out by
TGA and DSC respectively. The TGA result showed good thermal stability of N, N, N, N'-
Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide as functional agents of
polymer. Non-isothermal crystallization behavior indicated that NA as a kind of
heterogeneous nucleation agent can accelerate the overall PLLA crystallization. Upon the
addition of 0.5% N, N, N, N'-Tetra(benzoyl) ethylene diamine tetraacetic acid dihydrazide,
the crystallization temperature increased from 105.88°C to 116.12°C, and the crystallization
enthalpy increased from 1.379 J•g-1 to 41.41 J•g-1 at a cooling rate of 1°C/min from melt.
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