10.2417/spepro.005347
Characterizing petroleum
fermentation polyamide 11,11
Shaobing Liu and Qingxiang Zhao
The thermal and mechanical properties of petroleum fermentation
polyamide 11,11 reveal its suitability as an engineering plastic.
Polyamides are a subject of eternal interest owing to their variety,
complex internal structures, various preparations, and importance and
versatility in commercial applications. Their outstanding physical properties, which are attributed to their amide groups and the hydrogen
bonds between adjacent molecular chains, give most polyamides physical properties that make them useful engineering materials.1, 2 Among
polyamides, those with long alkyl chains attract particular attention
thanks to their lower water absorption, better dimensional stability, and
higher impact resistance.3
However, traditional long-alkyl-chain polyamides are complex to
synthesize. For example, the synthesis of polyamide 11 needs at least
six steps: interesterification, thermal cracking, hydrolysis, addition,
amination, and polymerization.4 This increases costs and limits
their applications. In contrast, diamines of petroleum fermentation
polyamide (PFPA) can be prepared by fermentation from light
wax.5, 6 This simplifies the synthetic process and reduces the cost.
We synthesized PFPA 11,11 based on the successful polymerization of PFPA 12,12.6 Undecanoic acid and 1,11-undecanediamine
(Zibo Guangtong Chemical Company, China) were used to synthesize
PFPA 11,11 by a two-step process of salt formation and polymerization.
We characterized PFPA 11,11 by measuring the melting point (Tm ),
crystallization temperature (Tc ), thermal degradation temperature (Td ),
and glass transition temperature (Tg ). We studied thermal behavior using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). The thermal
analyses (DSC and TGA) were recorded on a NETSCH 204 calorimeter
in a nitrogen stream. DMA was carried out on a NETZSCH DMA-242
system.
Both the heating and cooling DSC rates were 10◦C/min. We recorded
a second heating run to eliminate the effects of heating history. A big
melting peak indicates that Tm is approximately 181◦C (see Figure 1).
A small endothermic peak at about 150◦C was probably due to the
Brill transition, when one crystal phase changes into another in a
Figure 1. Differential scanning calorimetry (DSC) curves of petroleum
fermentation polyamide (PFPA) 11,11. Tm : Melting point. Tc : Crystallization temperature.
semi-crystalline polymer during continuous heating or cooling. During cooling from the melt, an endothermic peak occurred, indicating
that the crystallization temperature (Tc ) is about 140◦C.
TGA curves of PFPA 11,11 were recorded with a heating rate of
10◦C/min (see Figure 2). The curve shows a one-stage weight loss
process in nitrogen. We found Td of PFPA 11,11 was 397◦C, and the
termination temperature of thermal degradation was about 500◦C. The
maximum degradation temperature (Tmax ) of PFPA 11,11 was 470◦C,
indicating high thermal stability.7
We carried out DMA measurement in the bending mode at 33.3Hz
with a heating rate of 3◦C/min from 150 to 150◦C (see Figure 3).
Three obvious transition peaks can be observed and are defined as ˛,
ˇ, and relaxation, respectively. We measured Tg for PFPA 11,11 as
71◦C according to ˛ relaxation. The ˇ relaxation reflects the mobility
of the carbonyl group in the amorphous region, and the relaxation
reflects co-movement of amido and methenes. A small transition peak
is observed between the ˛ and ˇ peaks and is defined as ˇc , which we
ascribe to the absorption of water.8
For an engineering plastic, mechanical properties determine suitability for given applications, so we measured these (see Table 1).
First, we prepared all samples by injection molding. All tests were performed at room temperature, and the resulting value of each sample
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10.2417/spepro.005347 Page 2/2
Table 1. Mechanical properties of polyamide 11,11 compared to polyamide 11 and polyamide 12,12.
Samples
polyamide 11,11
polyamide 11
polyamide 12,12
Tensile
strength
(MPa)
46
50
56
Elongation
at break
(%)
345
330
370
was the average of five parallel experiments. Table 1 also shows the
mechanical properties of polyamide 11 and polyamide 12,12, revealing
that polyamide 11,11 has comparable mechanical properties to those of
polyamide 11 and polyamide 12,12. This indicates that PFPA 11,11 is,
like those materials, an excellent engineering plastic.
Tensile
modulus
(GPa)
1.4
1.5
1.4
Bending
strength
(MPa)
38
69
45
Bending
modulus
(GPa)
1.2
1.0
1.2
Izod impact
strength
(KJm 2 )
5.8
6.3
5.6
In summary, we synthesized and characterized the thermal and mechanical properties of PFPA 11,11, which possesses a Tm of approximately 181◦C, a Tg of approximately 71◦C, and high thermal stability.
PFPA 11,11 has similar mechanical properties to polyamide 11 and
polyamide 12,12, and like them is an excellent long alkyl chain
polyamide. It can therefore, like them, be used as an engineering plastic. Next, we will fabricate PFPA 11,11 into oil tubes and brake tubes,
and focus on its applications in the automobile industry.
Author Information
Shaobing Liu and Qingxiang Zhao
Zhengzhou University
Zhengzhou, China
References
Figure 2. Thermogravimetric (TG) and differential thermogravimetric
(DTG) curves of PFPA 11,11.
Figure 3. Dynamic mechanical analysis (DMA) curves of PFPA 11,11
obtained at 33.3Hz. ˛, ˇ, and : Transition peaks showing relaxations.
ˇc : Transition peak ascribed to the absorption of water.
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c 2014 Society of Plastics Engineers (SPE)