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Dynamic mechanical properties of chlorinated butyl rubber blends
EUROPEAN POLYMER JOURNAL
European Polymer Journal 42 (2006) 2507–2514
www.elsevier.com/locate/europolj
Dynamic mechanical properties of chlorinated butyl rubber blends Cong Li, Shi-Ai Xu, Fang-Yi Xiao, Chi-Fei Wu
*
Polymer Alloy Laboratory, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, PR China Received 12 March 2006; received in revised form 22 May 2006; accepted 5 June 2006 Available online 4 August 2006
Abstract The binary blends are prepared by chlorinated butyl rubber (CIIR) and 3,9-bis[1,1-dimethyl-2{b-(3-tert-butyl-4hydroxy-5-methylphenyl)propionyloxy}ethyl]-2, 4, 8,10-tetraoxaspiro[5,5]-undecane (AO-80), which are investigated by dynamic mechanical analysis and thermal analysis. It is shown that CIIR/AO-80 blends clearly exhibit two kinds of relaxations, which are attributed to the relaxation of CIIR-rich matrix and AO-80-rich domains, respectively, and attenuated total reflection (ATR)-FTIR spectrum indicates that the existence of intermolecular hydrogen bonds between AO-80 and CIIR. When AO-80 is replaced by petroleum resins, only one loss peak appears, and the position of it is related to the softening point and the content of the petroleum resin. In order to regulate the damping property of CIIR/petroleum resin blend, the ternary blend of CIIR/petroleum resin/AO-80/is prepared and a second peak appears at higher temperature indicating that a good damping material is obtained. 2006 Elsevier Ltd. All rights reserved. Keywords: Chlorinated butyl rubber; Petroleum resins; Damping; Hydrogen bond; Dynamic mechanical property
1. Introduction Viscoelastic properties of polymers make them ideally suitable for using as damping materials. Especially, polymers at the transition region from glassy to rubbery state have the great potential for vibration damping. In general, the damping capacity of a polymer is determined by the intensity and breadth of the loss tangent (tan d) peak and the value of the loss modulus at the use temperature.
*
Corresponding author. E-mail address: [email protected] (C.-F. Wu).
A great many efforts have been devoted to develop new materials with high damping capacity. Binary and ternary blends of polymers having different glass transition temperatures (Tg) are often used as damping materials [1–5]. When a moderate miscibility is achieved, a wide temperature range with high loss tangent is generally obtained. The interpenetrating polymer network (IPN) restricts the domain size to very small phase and enhances the degree of formation of a micro-heterogeneous structure, which results in a broad glass-transition region [6–11]. However, so far, the transitions of polymer blends and IPN are generally restricted to a relatively narrow temperature region.
0014-3057/$ - see front matter 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2006.06.004
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C. Li et al. / European Polymer Journal 42 (2006) 2507–2514
Petroleum resins, for instance, hydrogenated derivatives of C-5 and C-9 resins, are often added to an elastomer in order to improve the wettability and the adhesive strength on the surface. Here, C5 or C-9 resins respectively represent the aliphatic hydrocarbon resins having five carbon atoms per monomer or aromatic hydrocarbon resins having nine carbon atoms per monomer. These resins have molecular weights ranging from 300 to 3000 and usually exhibit a glassy state at room temperature [12–14]. In our previous research, it was found that the application of petroleum resins in the damping materials has not been reported. The purpose of this paper is to develop a high damping performance material with CIIR blends consisting of petroleum resins and investigate the additive effects of petroleum resins and hinderedphenol [15–21] 9-bis[1, 1-dimethyl-2{b-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2, 4,8,10-tetraoxaspiro[5,5]undecane (AO-80, chemical structural as shown in Fig. 1), on the dynamic mechanical properties of CIIR. For this purpose, CIIR/petroleum resin blends were prepared and studied to explore the possibility for damping application. Besides, AO-80 was added in order to enhance and regulate the damping property of CIIR/petroleum resin blend. 2. Experimental
Table 1 The softening point and glass transition temperature of petroleum resins in this study Code
P70
P90
P100
P115
P125
P140
Softening point/C Glass transition temperature/C
70 35
90 48
100 58
115 72
125 81
140 86
tow-mill for 8 min, then the petroleum resins were added. The kneaded samples were compression moulded into sheets with a thickness of about 2 mm under a pressure of 10 MPa for 15 min at 150 C, which is above the melting point of AO-80. 2.2. Dynamic mechanical analysis (DMA) Samples for DMA were cut from the compression-moulded sheet with a size of 20 · 4 · 2 mm, and the measurements were conducted on a dynamic mechanical analyzer (Rheogel-E4000; UBM Co.) at a heating rate of 3 C min1. The frequency was 11 Hz. 2.3. Differential scanning calorimetry (DSC) The thermal analysis with Netzsch calorimeter (200 PC) was used. Samples with a weight of about 10 mg were sealed in aluminum pans, and heated from 40 C to 80 C at a scanning rate of 10 C min1 under a nitrogen atmosphere.
2.1. Materials and sample preparation 2.4. Fourier transform infrared (FTIR) spectroscopy The CIIR used in this research, with a chlorination degree of 1.26 wt%, is a commercial grade (Exxon 1066; ExxonMobil Co.) and the mol% of unsaturation is 1.9 ± 0.2%. The AO-80 is a kind of antioxidant (ADK STAB AO-80; Asahi Denka Industries Co.). The second-order transition temperature and melting point of AO-80 are 42 C and 123 C, respectively [17]. The petroleum resins (as shown in Table 1) were from Arakawa Chemical Industries. The CIIR and AO-80 were kneaded by
Infrared spectra of AO-80 was obtained from an accumulation of 100 scans at a resolution of 2 cm1 with a JASCO FT-IRIII spectrometer, and the spectra were taken at ambient temperature of samples ground in KBr. The ATR–FTIR measurements for CIIR/AO-80 blends were carried out by using a Nicolet 20SXB-FTIR spectrometer. A KRS-5 crystal with an angle of incidence of 45 was used for recording the ATR spectra.
Fig. 1. Chemical structure of AO-80.
C. Li et al. / European Polymer Journal 42 (2006) 2507–2514
3. Results and discussion 3.1. Binary blends 3.1.1. Effects of AO-80 on dynamic mechanical properties of CIIR Figs. 2 and 3 shows the temperature dependence of the loss tangent (tan d) at 11 Hz for CIIR, CIIR/ AO-80 blends and AO-80, respectively. CIIR shows a broad tan d peak, in which the efficient damping (tan d > 0.5) has a wide temperature range more than 70 C. But it should be noted that the effective damping range of CIIR is at relatively low temperature. After addition of AO-80, a novel peak above the glass transition (Tg) of CIIR appears. Generally, in incompatible polymer blends, the magnitude of Tg peak is proportional to the content of the corresponding component, especially, when the blend
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ratio is 0.5, the first peak must extremely decrease [22]. However, the first peak of CIIR/AO-80(50) does not decrease dramatically and the second peak at higher temperature is obvious compared with the first peak. This phenomenon implies that the CIIR/ AO-80 system is probably different from usual completely incompatible polymer blend. During hot press process above the melting temperature of AO-80, a specific molecular-aggregation state probably is formed and the morphology has been kept when the CIIR/AO-80 system is cooled. With the inorganic fillers filled polymeric composites, an increase in the filler content leads to an enhancement of the storage modulus and a decrease in the maximum value of tan d, but the position of the tan d peak is constant. Fig. 4 shows the temperature dependence of the storage modulus E 0 for CIIR and CIIR/AO-80(50 phr). It can be seen from this figure that the E 0 curve of CIIR/AO-80(50 phr) shows three regions. The E 0 value of CIIR/AO80(50 phr) in the second region is higher than that of pure CIIR, which is similar to the addition effects of the inorganic fillers. However, compared with the E 0 of pure CIIR, CIIR/AO-80(50 phr) shows a significantly lower E 0 in the third region. On the other hand, the shift of the first tan d peak (Fig. 2) to a higher temperature with the increase of AO-80 is not observed for usual fillers. In order to confirm the interaction between CIIR and AO-80, ATR-FTIR spectroscopy was used. Fig. 5 shows the infrared spectrum in the hydroxyl groups stretching region for AO-80, CIIR/AO80(50) and CIIR/AO-80(30). The spectrum of AO80 indicates a significant absorption at 3500 cm1,
Fig. 2. The temperature dependence of loss tangent (tan d) at 11 Hz for CIIR and CIIR/AO-80.
Fig. 3. The temperature dependence of dynamic mechanical properties at 11 Hz for AO-80.
Fig. 4. The temperature dependence of storage modulus (E 0 ) at 11 Hz for CIIR and CIIR/AO-80(50 phr).
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Fig. 5. Infrared spectrum in the hydroxyl groups stretching region for AO-80, CIIR/AO-80(50) and CIIR/AO-80(30).
which is attributed to an intermolecular interaction between OH and p-electrons of benzene ring of AO80 [23]. For CIIR/AO-80(50), the band shifts to a lower wavenumber at 3440 cm1, this band can be assigned to an intermolecular hydrogen bond between OH of AO-80 and Cl of CIIR. This illustrates that hydrogen bond between OH and p-electrons of benzene ring is replaced by the hydrogen bond between OH and Cl, which implies the domains of AO-80 within CIIR matrix include a large amount of CIIR segments. It also can be found a band at 3350 cm1 appears for CIIR/AO80(30), compared with CIIR/AO-80(50), the band is located at a lower wavenumber. This means that with the increase in the weight ratio of CIIR, the bond energy of OH–Cl becomes larger and the band attributed to the O–H appears at lower wavenumber. Thus, the existence of hydrogen bonds between the CIIR and AO-80 is made certain, and a large amount of AO-80 rich domains are dispersed in the matrix CIIR. The AO-80 rich domains include a large amount of CIIR segments, and weaker interactions between CIIR chains are partially replaced by stronger interactions between CIIR chains and AO-80 molecules. The stronger interaction suppresses the mobility of CIIR chains and results in the first tan d peak (Fig. 2) to a higher temperature. It can be also seen from Fig. 2, the position of the second peak is almost kept constant. In addition, DSC curves for CIIR/AO-80 (Fig. 6) show that the transition temperature of CIIR/AO-80 is at about 42 C, so the second tan d peak (Fig. 2) is attributed to the dissociation of intermolecular hydrogen bonds of AO-80.
Fig. 6. DSC thermograms of CIIR, AO-80 and CIIR/AO-80 blends.
Based on the discussion above, the variation of E 0 in Fig. 4 can be explained. The AO-80-rich domains showing higher modulus act as crosslink points and lead to the E 0 in the second region is higher than that of pure CIIR. With the increase of temperature, the hydrogen bonds of AO-80 begin to dissociate so that the AO-80 domains can not behave as junction points, on the contrary, they act as plasticizer and result in the E 0 in the third region is lower than that of pure CIIR. Due to the appearance of the second peak at higher temperature, wider application for damping materials is available. However, it should be noted that for these systems, the tan d values in the range between the two peaks are relatively low. 3.1.2. Effects of petroleum resins on dynamic mechanical properties of CIIR In order to compare the effects of different petroleum resins to the damping properties of CIIR, six petroleum resins were blended with CIIR keeping the content of petroleum resins constant. Fig. 7 shows the temperature dependence of loss tangent (tan d) at 11 Hz for CIIR blends added with various petroleum resins. As shown in the figure, CIIR/ petroleum resins blends show a single tan d peak associated with CIIR, and the peak location shifts to higher temperature with increasing the softening points of petroleum resins. In general, the glass transition temperature of petroleum resin is fifty degrees lower than the softening point, so the higher the softening point is, the higher the tan d peak temperature of the blended CIIR. The single tan d peak
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as TA, can be considered to be a damping index, which is a measure of the energy dissipation of a transition process [24]. The TA values of CIIR/ petroleum resins blends are also summarized in Table 2. Comparing with many IPNs [6] having two overlapping peaks, CIIR/petroleum resin blends exhibit relatively high TA value.
Fig. 7. The temperature dependence of tan d at 11 Hz for CIIR/ petroleum resins (150 phr) blends.
of CIIR/petroleum resins blends demonstrate that petroleum resins are compatible with CIIR. Moreover, it can be found from Fig. 7 and Table 2, a broad and intense tan d peak has been obtained. The loss tangent (tan d), which indicates the damping ability of the material, is the ratio of the mechanical dissipation energy to the storage energy. Thus, a high tan d value is essential for good damping materials. Table 2 shows that the loss tangent maximum (tan d max) of CIIR/petroleum resins blends. The different values of tan d max in CIIR/ petroleum resin blends may be attributed to the dissimilar interactions between the chains of CIIR and petroleum resins molecules. As shown in Fig. 7, all CIIR/petroleum resins blends have efficient damping (tan d > 0.5) over a wide temperature range more than 74 C. Especially, the CIIR/P70 blend exhibits high damping at room temperature, and shows efficient damping (tan d > 0.5) over a wide temperature range from 0 C to 76 C (DT = 76 C). On the other hand, the peak area under the tan d temperature curves, which is abbreviated
3.1.3. Effects of P70 content on dynamic mechanical properties of CIIR Fig. 8 shows the effect of P70 content on the temperature dependence of the loss tangent (tan d) at 11 Hz for various CIIR/P70 blends. As shown in the figure, the CIIR/P70 blends exhibit a single tan d peak associated with CIIR, and the maximum value of the tan d peak increases and the peak location shifts to higher temperature with increasing the content of P70, which is quite different from the behaviors of CIIR/AO-80 blends (Fig. 2), indicating P70 is compatible with CIIR.
Fig. 8. The temperature dependence of tan d at 11 Hz for CIIR/ P70 blends.
Table 2 The damping properties of CIIR/petroleum resins (100:150) blends Sample code
CIIR/P70 CIIR/P90 CIIR/P100 CIIR/P115 CIIR/P125 CIIR/P140
tan d max
Temperature range of tan d > 0.5
Temperature range of tan d > 1.0
Value
T/C
T1/C
T2/C
DT/C
T1/C
T2/C
DT/C
2.73 1.51 1.73 2.23 2.07 1.68
31.8 49.8 56.9 63.9 67.9 81.8
0 10 15 25 31 43
76 87 99 105 112 >117
76 77 84 80 81 >74
11 30 33 42 48 61
58 70 77 87 92 103
47 40 44 45 44 42
TA/C
83.2 41.3 54.9 63.7 64.8 42.0
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Fig. 9. The temperature dependence of the addition effects of P70 on the storage modulus E 0 of CIIR.
Fig. 9 shows the temperature dependence of the addition effects of P70 on the storage modulus E 0 of CIIR. The E 0 values in the glassy region increase with P70 content increase, whereas those in the rubbery region decrease significantly. The relaxation strength (r) here can be defined as follows: R ¼ ðEg Er Þ=Er
ð1Þ
Where Eg is the glassy modulus at 40 C, and Er is the rubbery modulus at 65 C. The height of the tan d peak as a function of relaxation strength can be seen in Fig. 10, which indicates that for CIIR/ P70 the relaxation strength of its glass transition is proportional to the height of the tan d peak. On the other hand, the height of tan d peak and temperature for tan d peak increase linearly with increasing the content of P70, as shown in Figs. 11 and 12. Moreover, it can be found in Fig. 8 and
Fig. 10. Height of the tan d peak as a function of relaxation strength for CIIR/P70.
Fig. 11. Height of the tan d peak as a function of P70 content for CIIR/P70.
Table 3, although the location of temperature range for efficient damping (tan d > 0.5) shifts to higher temperature with increasing the content of P70, temperature range for efficient damping (tan d > 0.5) almost keeps constant. Therefore, changing the content of P70, temperature range for efficient damping (tan d > 0.5) can be adjusted to fit different application fields. 3.2. Ternary blends In order to obtain a wider temperature range for efficient damping (tan d > 0.5), the CIIR/P70/AO-80 (100:100:50) ternary blend was investigated. As shown in Fig. 13, after the addition of AO-80, CIIR/ P70/AO-80/blend exhibits a second peak at higher temperature. This leads to the efficient
Fig. 12. Temperature of the tan d peak as a function of P70 content for CIIR/P70.
C. Li et al. / European Polymer Journal 42 (2006) 2507–2514
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Table 3 The damping properties of CIIR/P70 blends Sample codea
P70-50 P70-100 P70-150 P70-200 a
Temperature range of tan d > 0.5
Temperature range of tan d > 1.0
Value
tan d max T/C
T1/C
T2/C
DT/C
T1/C
T2/C
DT/C
1.82 2.25 2.73 3.25
6.9 19.9 31.8 39.0
29 11 0 6
48 63 76 –
77 74 76 –
16 0 11 17
31 46 56 65
47 46 45 48
P70 denotes the code of the petroleum resin, while the second number denotes the P70 content in CIIR/P70.
Fig. 13. The temperature dependence of tan d at 11 Hz for CIIR/ P70 and CIIR/P70/AO-80.
damping (tan d > 0.5) covers a wider temperature range than that of CIIR/P70(100:100) (DT = 76 C), ranging from 10 C to 80 C(DT = 90 C). The second peak at higher temperature is associated with the dissociation of intermolecular hydrogen bonds of AO-80, while the first peak corresponds to the glass transition of CIIR-rich phase. Fig. 14 shows the temperature dependence of the storage modulus E 0 for CIIR, CIIR/P70 and CIIR/ P70/AO-80, respectively. The E 0 value of CIIR/ P70/AO-80(100:100:50) is higher than that of CIIR/P70(100:100) over the experimental temperature range. This is probably because the AO-80-rich domains showing higher modulus act as crosslink points, which is similar to addition effect of AO-80 in CIIR/AO-80 system. However, the E 0 of CIIR/ P70/AO-80 in the rubbery region is lower than that of pure CIIR, this is because the existence of P70 reduces the intermolecular interaction between the chains of CIIR and the additives. Fig. 15 shows the temperature dependence of the loss modulus E00 for CIIR/P70 and CIIR/P70/AO80. Just like the E 0 , E00 value of CIIR/P70/AO-80/ (100:100:50) is higher than that of CIIR/P70
Fig. 14. The temperature dependence of the storage modulus E 0 for CIIR, CIIR/P70 and CIIR/P7O/AO-80.
Fig. 15. The temperature dependence of the loss modulus E00 for CIIR/P70 and CIIR/P70/AO-80.
(100:100) over the experimental temperature range. Ungar pointed out that for a constrained damping structure, the damping capacity is dominated by the cooperation of the loss tangent and loss modulus of the polymer, higher loss modulus will conduce to the improvement of damping capacity [25]. Thus,
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CIIR/P70/AO-80 (100:100:50) has a better damping capacity than that of CIIR/P70 (100:100). 4. Conclusion The effects of AO-80 and petroleum resins on the dynamic mechanical properties of CIIR were investigated. CIIR/AO-80 blends clearly exhibit two kinds of relaxations. The first relaxation is attributed to the glass transition of the CIIR-rich matrix, whereas the second relaxation is associated with the existence of AO-80-rich domains. The CIIR/petroleum resin blend only shows a single tan d peak, and the position of it is related to the softening point and the content of the petroleum resin. Regulating them, good damping properties can be realized, especially, P70 has the most excellent damping endowed function. Compared with CIIR/P70 (100:100), CIIR/P70/ AO-80 (100:100:50) has a wider temperature range of efficient damping (tan d > 0.5), and the higher loss modulus E00 of CIIR/P70/AO-80 (100:100:50) implies that a better damping performance is obtained. References [1] Corsaro RD, Sperling LH. Sound and vibration damping with polymers. Washington, DC: American Chemical Society; 1990. [2] Ogawa T. J Adhesion Soc 1998;34:263.
[3] Shucai L, Weijiang P, Xiuping L. Int J Polym Mater 1995;29:37. [4] Wang J, Liu R, Li W, Li Y, Tang X. Polym Int 1996;39: 101. [5] Ting RY, Capps RN, Klempner D. Polym Mater Sci Eng 1989;60:654. [6] Hu R, Dimonie VL, El-Aaser MS, Pearson RA, Hiltner A, Mylonakis SG, Sperling LH. J Polym Sci Part B: Polym Phys 1997;35:1501. [7] Chen Ge, Chen D, He X, Yu X. J Appl Polym Sci 1994;54:1191. [8] Peng W, Li S. J Appl Polym Sci 1995;58:967. [9] Yu X, Gao G, Wang J, Li F, Tang X. Polym Int 1999;48:805. [10] Wei Z, Li S. J Appl Polym Sci 2002;84:821. [11] Li S, Qiu Q. J Appl Polym Sci 2000;76:722. [12] Kim J, Ryu D, Lee K. Polymer 2000;41:5195. [13] Ryu D, Kim J. Polymer 2000;41:5207. [14] Donatas S. Handbook of pressure-sensitive adhesive technology. New York, 1982. [15] Wu C, Yamagishi T, Nakamoto Y, Ishida S, Nitta K, Kubota S. J Polym Sci Part B: Polym Phys 2000;38:1341. [16] Wu C, Yamagishi T, Nakamoto Y, Ishida S, Nitta K, Kubota S. J Polym Sci Part B: Polym Phys 2000;38:1496. [17] Wu C, Yamagishi T, Nakamoto Y, Ishida S, Nitta K, Kubota S. J Polym Sci Part B: Polym Phys 2000;38:2285. [18] Wu C. Chinese J Polym Sci 2001;19:455. [19] Wu C. J Appl Polym Sci 2001;80:2468. [20] Wu C. J Polym Sci Part B: Polym Phys 2001;39:23. [21] Wu C. Chinese J Polym Sci 2001;20:119. [22] Yamada N, Shoji S, Sasaki A, Nagatani A, Yamaguchi K, Kohjiya S, Hashim A. J Appl Polym Sci 1999;71:855. [23] Wu C. J Non-Cryst Solids 2003;315:321. [24] Hajime K, Kiyohiro I, Yoichi T, Shigeo A, Masao S. Mater Lett 2002;52:96. [25] Ungar E. J Acoust Soc Am 1962;34:1082.
European Polymer Journal 42 (2006) 2507–2514
www.elsevier.com/locate/europolj
Dynamic mechanical properties of chlorinated butyl rubber blends Cong Li, Shi-Ai Xu, Fang-Yi Xiao, Chi-Fei Wu
*
Polymer Alloy Laboratory, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, PR China Received 12 March 2006; received in revised form 22 May 2006; accepted 5 June 2006 Available online 4 August 2006
Abstract The binary blends are prepared by chlorinated butyl rubber (CIIR) and 3,9-bis[1,1-dimethyl-2{b-(3-tert-butyl-4hydroxy-5-methylphenyl)propionyloxy}ethyl]-2, 4, 8,10-tetraoxaspiro[5,5]-undecane (AO-80), which are investigated by dynamic mechanical analysis and thermal analysis. It is shown that CIIR/AO-80 blends clearly exhibit two kinds of relaxations, which are attributed to the relaxation of CIIR-rich matrix and AO-80-rich domains, respectively, and attenuated total reflection (ATR)-FTIR spectrum indicates that the existence of intermolecular hydrogen bonds between AO-80 and CIIR. When AO-80 is replaced by petroleum resins, only one loss peak appears, and the position of it is related to the softening point and the content of the petroleum resin. In order to regulate the damping property of CIIR/petroleum resin blend, the ternary blend of CIIR/petroleum resin/AO-80/is prepared and a second peak appears at higher temperature indicating that a good damping material is obtained. 2006 Elsevier Ltd. All rights reserved. Keywords: Chlorinated butyl rubber; Petroleum resins; Damping; Hydrogen bond; Dynamic mechanical property
1. Introduction Viscoelastic properties of polymers make them ideally suitable for using as damping materials. Especially, polymers at the transition region from glassy to rubbery state have the great potential for vibration damping. In general, the damping capacity of a polymer is determined by the intensity and breadth of the loss tangent (tan d) peak and the value of the loss modulus at the use temperature.
*
Corresponding author. E-mail address: [email protected] (C.-F. Wu).
A great many efforts have been devoted to develop new materials with high damping capacity. Binary and ternary blends of polymers having different glass transition temperatures (Tg) are often used as damping materials [1–5]. When a moderate miscibility is achieved, a wide temperature range with high loss tangent is generally obtained. The interpenetrating polymer network (IPN) restricts the domain size to very small phase and enhances the degree of formation of a micro-heterogeneous structure, which results in a broad glass-transition region [6–11]. However, so far, the transitions of polymer blends and IPN are generally restricted to a relatively narrow temperature region.
0014-3057/$ - see front matter 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2006.06.004
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C. Li et al. / European Polymer Journal 42 (2006) 2507–2514
Petroleum resins, for instance, hydrogenated derivatives of C-5 and C-9 resins, are often added to an elastomer in order to improve the wettability and the adhesive strength on the surface. Here, C5 or C-9 resins respectively represent the aliphatic hydrocarbon resins having five carbon atoms per monomer or aromatic hydrocarbon resins having nine carbon atoms per monomer. These resins have molecular weights ranging from 300 to 3000 and usually exhibit a glassy state at room temperature [12–14]. In our previous research, it was found that the application of petroleum resins in the damping materials has not been reported. The purpose of this paper is to develop a high damping performance material with CIIR blends consisting of petroleum resins and investigate the additive effects of petroleum resins and hinderedphenol [15–21] 9-bis[1, 1-dimethyl-2{b-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2, 4,8,10-tetraoxaspiro[5,5]undecane (AO-80, chemical structural as shown in Fig. 1), on the dynamic mechanical properties of CIIR. For this purpose, CIIR/petroleum resin blends were prepared and studied to explore the possibility for damping application. Besides, AO-80 was added in order to enhance and regulate the damping property of CIIR/petroleum resin blend. 2. Experimental
Table 1 The softening point and glass transition temperature of petroleum resins in this study Code
P70
P90
P100
P115
P125
P140
Softening point/C Glass transition temperature/C
70 35
90 48
100 58
115 72
125 81
140 86
tow-mill for 8 min, then the petroleum resins were added. The kneaded samples were compression moulded into sheets with a thickness of about 2 mm under a pressure of 10 MPa for 15 min at 150 C, which is above the melting point of AO-80. 2.2. Dynamic mechanical analysis (DMA) Samples for DMA were cut from the compression-moulded sheet with a size of 20 · 4 · 2 mm, and the measurements were conducted on a dynamic mechanical analyzer (Rheogel-E4000; UBM Co.) at a heating rate of 3 C min1. The frequency was 11 Hz. 2.3. Differential scanning calorimetry (DSC) The thermal analysis with Netzsch calorimeter (200 PC) was used. Samples with a weight of about 10 mg were sealed in aluminum pans, and heated from 40 C to 80 C at a scanning rate of 10 C min1 under a nitrogen atmosphere.
2.1. Materials and sample preparation 2.4. Fourier transform infrared (FTIR) spectroscopy The CIIR used in this research, with a chlorination degree of 1.26 wt%, is a commercial grade (Exxon 1066; ExxonMobil Co.) and the mol% of unsaturation is 1.9 ± 0.2%. The AO-80 is a kind of antioxidant (ADK STAB AO-80; Asahi Denka Industries Co.). The second-order transition temperature and melting point of AO-80 are 42 C and 123 C, respectively [17]. The petroleum resins (as shown in Table 1) were from Arakawa Chemical Industries. The CIIR and AO-80 were kneaded by
Infrared spectra of AO-80 was obtained from an accumulation of 100 scans at a resolution of 2 cm1 with a JASCO FT-IRIII spectrometer, and the spectra were taken at ambient temperature of samples ground in KBr. The ATR–FTIR measurements for CIIR/AO-80 blends were carried out by using a Nicolet 20SXB-FTIR spectrometer. A KRS-5 crystal with an angle of incidence of 45 was used for recording the ATR spectra.
Fig. 1. Chemical structure of AO-80.
C. Li et al. / European Polymer Journal 42 (2006) 2507–2514
3. Results and discussion 3.1. Binary blends 3.1.1. Effects of AO-80 on dynamic mechanical properties of CIIR Figs. 2 and 3 shows the temperature dependence of the loss tangent (tan d) at 11 Hz for CIIR, CIIR/ AO-80 blends and AO-80, respectively. CIIR shows a broad tan d peak, in which the efficient damping (tan d > 0.5) has a wide temperature range more than 70 C. But it should be noted that the effective damping range of CIIR is at relatively low temperature. After addition of AO-80, a novel peak above the glass transition (Tg) of CIIR appears. Generally, in incompatible polymer blends, the magnitude of Tg peak is proportional to the content of the corresponding component, especially, when the blend
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ratio is 0.5, the first peak must extremely decrease [22]. However, the first peak of CIIR/AO-80(50) does not decrease dramatically and the second peak at higher temperature is obvious compared with the first peak. This phenomenon implies that the CIIR/ AO-80 system is probably different from usual completely incompatible polymer blend. During hot press process above the melting temperature of AO-80, a specific molecular-aggregation state probably is formed and the morphology has been kept when the CIIR/AO-80 system is cooled. With the inorganic fillers filled polymeric composites, an increase in the filler content leads to an enhancement of the storage modulus and a decrease in the maximum value of tan d, but the position of the tan d peak is constant. Fig. 4 shows the temperature dependence of the storage modulus E 0 for CIIR and CIIR/AO-80(50 phr). It can be seen from this figure that the E 0 curve of CIIR/AO-80(50 phr) shows three regions. The E 0 value of CIIR/AO80(50 phr) in the second region is higher than that of pure CIIR, which is similar to the addition effects of the inorganic fillers. However, compared with the E 0 of pure CIIR, CIIR/AO-80(50 phr) shows a significantly lower E 0 in the third region. On the other hand, the shift of the first tan d peak (Fig. 2) to a higher temperature with the increase of AO-80 is not observed for usual fillers. In order to confirm the interaction between CIIR and AO-80, ATR-FTIR spectroscopy was used. Fig. 5 shows the infrared spectrum in the hydroxyl groups stretching region for AO-80, CIIR/AO80(50) and CIIR/AO-80(30). The spectrum of AO80 indicates a significant absorption at 3500 cm1,
Fig. 2. The temperature dependence of loss tangent (tan d) at 11 Hz for CIIR and CIIR/AO-80.
Fig. 3. The temperature dependence of dynamic mechanical properties at 11 Hz for AO-80.
Fig. 4. The temperature dependence of storage modulus (E 0 ) at 11 Hz for CIIR and CIIR/AO-80(50 phr).
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Fig. 5. Infrared spectrum in the hydroxyl groups stretching region for AO-80, CIIR/AO-80(50) and CIIR/AO-80(30).
which is attributed to an intermolecular interaction between OH and p-electrons of benzene ring of AO80 [23]. For CIIR/AO-80(50), the band shifts to a lower wavenumber at 3440 cm1, this band can be assigned to an intermolecular hydrogen bond between OH of AO-80 and Cl of CIIR. This illustrates that hydrogen bond between OH and p-electrons of benzene ring is replaced by the hydrogen bond between OH and Cl, which implies the domains of AO-80 within CIIR matrix include a large amount of CIIR segments. It also can be found a band at 3350 cm1 appears for CIIR/AO80(30), compared with CIIR/AO-80(50), the band is located at a lower wavenumber. This means that with the increase in the weight ratio of CIIR, the bond energy of OH–Cl becomes larger and the band attributed to the O–H appears at lower wavenumber. Thus, the existence of hydrogen bonds between the CIIR and AO-80 is made certain, and a large amount of AO-80 rich domains are dispersed in the matrix CIIR. The AO-80 rich domains include a large amount of CIIR segments, and weaker interactions between CIIR chains are partially replaced by stronger interactions between CIIR chains and AO-80 molecules. The stronger interaction suppresses the mobility of CIIR chains and results in the first tan d peak (Fig. 2) to a higher temperature. It can be also seen from Fig. 2, the position of the second peak is almost kept constant. In addition, DSC curves for CIIR/AO-80 (Fig. 6) show that the transition temperature of CIIR/AO-80 is at about 42 C, so the second tan d peak (Fig. 2) is attributed to the dissociation of intermolecular hydrogen bonds of AO-80.
Fig. 6. DSC thermograms of CIIR, AO-80 and CIIR/AO-80 blends.
Based on the discussion above, the variation of E 0 in Fig. 4 can be explained. The AO-80-rich domains showing higher modulus act as crosslink points and lead to the E 0 in the second region is higher than that of pure CIIR. With the increase of temperature, the hydrogen bonds of AO-80 begin to dissociate so that the AO-80 domains can not behave as junction points, on the contrary, they act as plasticizer and result in the E 0 in the third region is lower than that of pure CIIR. Due to the appearance of the second peak at higher temperature, wider application for damping materials is available. However, it should be noted that for these systems, the tan d values in the range between the two peaks are relatively low. 3.1.2. Effects of petroleum resins on dynamic mechanical properties of CIIR In order to compare the effects of different petroleum resins to the damping properties of CIIR, six petroleum resins were blended with CIIR keeping the content of petroleum resins constant. Fig. 7 shows the temperature dependence of loss tangent (tan d) at 11 Hz for CIIR blends added with various petroleum resins. As shown in the figure, CIIR/ petroleum resins blends show a single tan d peak associated with CIIR, and the peak location shifts to higher temperature with increasing the softening points of petroleum resins. In general, the glass transition temperature of petroleum resin is fifty degrees lower than the softening point, so the higher the softening point is, the higher the tan d peak temperature of the blended CIIR. The single tan d peak
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as TA, can be considered to be a damping index, which is a measure of the energy dissipation of a transition process [24]. The TA values of CIIR/ petroleum resins blends are also summarized in Table 2. Comparing with many IPNs [6] having two overlapping peaks, CIIR/petroleum resin blends exhibit relatively high TA value.
Fig. 7. The temperature dependence of tan d at 11 Hz for CIIR/ petroleum resins (150 phr) blends.
of CIIR/petroleum resins blends demonstrate that petroleum resins are compatible with CIIR. Moreover, it can be found from Fig. 7 and Table 2, a broad and intense tan d peak has been obtained. The loss tangent (tan d), which indicates the damping ability of the material, is the ratio of the mechanical dissipation energy to the storage energy. Thus, a high tan d value is essential for good damping materials. Table 2 shows that the loss tangent maximum (tan d max) of CIIR/petroleum resins blends. The different values of tan d max in CIIR/ petroleum resin blends may be attributed to the dissimilar interactions between the chains of CIIR and petroleum resins molecules. As shown in Fig. 7, all CIIR/petroleum resins blends have efficient damping (tan d > 0.5) over a wide temperature range more than 74 C. Especially, the CIIR/P70 blend exhibits high damping at room temperature, and shows efficient damping (tan d > 0.5) over a wide temperature range from 0 C to 76 C (DT = 76 C). On the other hand, the peak area under the tan d temperature curves, which is abbreviated
3.1.3. Effects of P70 content on dynamic mechanical properties of CIIR Fig. 8 shows the effect of P70 content on the temperature dependence of the loss tangent (tan d) at 11 Hz for various CIIR/P70 blends. As shown in the figure, the CIIR/P70 blends exhibit a single tan d peak associated with CIIR, and the maximum value of the tan d peak increases and the peak location shifts to higher temperature with increasing the content of P70, which is quite different from the behaviors of CIIR/AO-80 blends (Fig. 2), indicating P70 is compatible with CIIR.
Fig. 8. The temperature dependence of tan d at 11 Hz for CIIR/ P70 blends.
Table 2 The damping properties of CIIR/petroleum resins (100:150) blends Sample code
CIIR/P70 CIIR/P90 CIIR/P100 CIIR/P115 CIIR/P125 CIIR/P140
tan d max
Temperature range of tan d > 0.5
Temperature range of tan d > 1.0
Value
T/C
T1/C
T2/C
DT/C
T1/C
T2/C
DT/C
2.73 1.51 1.73 2.23 2.07 1.68
31.8 49.8 56.9 63.9 67.9 81.8
0 10 15 25 31 43
76 87 99 105 112 >117
76 77 84 80 81 >74
11 30 33 42 48 61
58 70 77 87 92 103
47 40 44 45 44 42
TA/C
83.2 41.3 54.9 63.7 64.8 42.0
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Fig. 9. The temperature dependence of the addition effects of P70 on the storage modulus E 0 of CIIR.
Fig. 9 shows the temperature dependence of the addition effects of P70 on the storage modulus E 0 of CIIR. The E 0 values in the glassy region increase with P70 content increase, whereas those in the rubbery region decrease significantly. The relaxation strength (r) here can be defined as follows: R ¼ ðEg Er Þ=Er
ð1Þ
Where Eg is the glassy modulus at 40 C, and Er is the rubbery modulus at 65 C. The height of the tan d peak as a function of relaxation strength can be seen in Fig. 10, which indicates that for CIIR/ P70 the relaxation strength of its glass transition is proportional to the height of the tan d peak. On the other hand, the height of tan d peak and temperature for tan d peak increase linearly with increasing the content of P70, as shown in Figs. 11 and 12. Moreover, it can be found in Fig. 8 and
Fig. 10. Height of the tan d peak as a function of relaxation strength for CIIR/P70.
Fig. 11. Height of the tan d peak as a function of P70 content for CIIR/P70.
Table 3, although the location of temperature range for efficient damping (tan d > 0.5) shifts to higher temperature with increasing the content of P70, temperature range for efficient damping (tan d > 0.5) almost keeps constant. Therefore, changing the content of P70, temperature range for efficient damping (tan d > 0.5) can be adjusted to fit different application fields. 3.2. Ternary blends In order to obtain a wider temperature range for efficient damping (tan d > 0.5), the CIIR/P70/AO-80 (100:100:50) ternary blend was investigated. As shown in Fig. 13, after the addition of AO-80, CIIR/ P70/AO-80/blend exhibits a second peak at higher temperature. This leads to the efficient
Fig. 12. Temperature of the tan d peak as a function of P70 content for CIIR/P70.
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Table 3 The damping properties of CIIR/P70 blends Sample codea
P70-50 P70-100 P70-150 P70-200 a
Temperature range of tan d > 0.5
Temperature range of tan d > 1.0
Value
tan d max T/C
T1/C
T2/C
DT/C
T1/C
T2/C
DT/C
1.82 2.25 2.73 3.25
6.9 19.9 31.8 39.0
29 11 0 6
48 63 76 –
77 74 76 –
16 0 11 17
31 46 56 65
47 46 45 48
P70 denotes the code of the petroleum resin, while the second number denotes the P70 content in CIIR/P70.
Fig. 13. The temperature dependence of tan d at 11 Hz for CIIR/ P70 and CIIR/P70/AO-80.
damping (tan d > 0.5) covers a wider temperature range than that of CIIR/P70(100:100) (DT = 76 C), ranging from 10 C to 80 C(DT = 90 C). The second peak at higher temperature is associated with the dissociation of intermolecular hydrogen bonds of AO-80, while the first peak corresponds to the glass transition of CIIR-rich phase. Fig. 14 shows the temperature dependence of the storage modulus E 0 for CIIR, CIIR/P70 and CIIR/ P70/AO-80, respectively. The E 0 value of CIIR/ P70/AO-80(100:100:50) is higher than that of CIIR/P70(100:100) over the experimental temperature range. This is probably because the AO-80-rich domains showing higher modulus act as crosslink points, which is similar to addition effect of AO-80 in CIIR/AO-80 system. However, the E 0 of CIIR/ P70/AO-80 in the rubbery region is lower than that of pure CIIR, this is because the existence of P70 reduces the intermolecular interaction between the chains of CIIR and the additives. Fig. 15 shows the temperature dependence of the loss modulus E00 for CIIR/P70 and CIIR/P70/AO80. Just like the E 0 , E00 value of CIIR/P70/AO-80/ (100:100:50) is higher than that of CIIR/P70
Fig. 14. The temperature dependence of the storage modulus E 0 for CIIR, CIIR/P70 and CIIR/P7O/AO-80.
Fig. 15. The temperature dependence of the loss modulus E00 for CIIR/P70 and CIIR/P70/AO-80.
(100:100) over the experimental temperature range. Ungar pointed out that for a constrained damping structure, the damping capacity is dominated by the cooperation of the loss tangent and loss modulus of the polymer, higher loss modulus will conduce to the improvement of damping capacity [25]. Thus,
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CIIR/P70/AO-80 (100:100:50) has a better damping capacity than that of CIIR/P70 (100:100). 4. Conclusion The effects of AO-80 and petroleum resins on the dynamic mechanical properties of CIIR were investigated. CIIR/AO-80 blends clearly exhibit two kinds of relaxations. The first relaxation is attributed to the glass transition of the CIIR-rich matrix, whereas the second relaxation is associated with the existence of AO-80-rich domains. The CIIR/petroleum resin blend only shows a single tan d peak, and the position of it is related to the softening point and the content of the petroleum resin. Regulating them, good damping properties can be realized, especially, P70 has the most excellent damping endowed function. Compared with CIIR/P70 (100:100), CIIR/P70/ AO-80 (100:100:50) has a wider temperature range of efficient damping (tan d > 0.5), and the higher loss modulus E00 of CIIR/P70/AO-80 (100:100:50) implies that a better damping performance is obtained. References [1] Corsaro RD, Sperling LH. Sound and vibration damping with polymers. Washington, DC: American Chemical Society; 1990. [2] Ogawa T. J Adhesion Soc 1998;34:263.
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