外文翻譯--納米二氧化硅和尼龍66的復(fù)合物的表面結(jié)構(gòu)及其對(duì)材料機(jī)械性能和熱性能的影響（英文）

1、The interface structure of nano-SiO2/PA66 composites and its influence on material’s mechanical and thermal propertiesXiangmin Xu a, Binjie Li a, Huimin Lu a, Zhijun Zhang a,*, Honggang Wang ba Key Lab for Special Functi

2、onal Materials, Henan University, Kaifeng, Henan 475000, China b State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, ChinaReceived 19 Janu

3、ary 2007; accepted 2 July 2007 Available online 10 July 2007AbstractThe PA66-based nanocomposites containing surface-modified nano-SiO2 were prepared by melt compounding. The interface structure formed in composite syste

4、m was investigated by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The influence of interface struc

5、ture on material’s mechanical and thermal properties was also studied. The results indicated that the PA66 chains were attached to the surface of modified-silica nanoparticles by chemical bonding and physical absorption

6、mode, accompanying the formation of the composites network structure. With the addition of modified silica, the strength and stiffness of composites were all reinforced: the observed increase depended on the formation of

7、 the interface structure based on hydrogen bonding and covalent bonding. Furthermore, the differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) showed that the presence of modified silica could af

8、fect the crystallization behavior of the PA66 matrix and lead to glass transition temperature of composites a shift to higher temperature. # 2007 Elsevier B.V. All rights reserved.Keywords: Interface structure; Nano-SiO2

9、; Thermal properties; Mechanical properties1. IntroductionPolymer-based nanocomposites are presently seen as one of the most promising materials in the field of future engineering applications. Some studies have shown th

10、at fully and uniformly dispersing nanoparticles in the polymer matrix can markedly improve the properties of materials, such as enhanced mechanical and thermal properties, and improved barrier performance and flame retar

11、dancy [1–6]. Furthermore, these improvements are achieved at low contents of nanofillers, and it is obviously different from conventional filled polymers, which generally require high loadings. However, the applications

12、of polymer-based nanocompo- sites are also limited due to the strong agglomeration tendency of nanofillers. To obtain better dispersion in polymer matrix,nanofillers are usually pretreated by different surface modified t

13、echnology. The chemical treatment of nanoparticles surface is one of the common methods where coupling agent, surfactant and polymer are often used as surface modifier. The end groups of these modifier molecules can inte

14、ract with nanoparticles surface by physical or chemical mode and make modifier molecules attached or grafted to the nanoparticles surface. The appropriate surface modification on nanoparticles could not only make for bet

15、ter dispersion in the polymer matrix, but also increase the compatibility with the matrix, and further bring on influence on the interface structure. It is well known that the interface structure between the matrix and f

16、illers plays an important role in determining the properties of material. Recent research has focused on possible mechanisms for the formation of interface structure and the influences of different interface structure on

17、 the material’s properties. Li et al. [7] studied the effects of polyamide-6 with different surface-modified silica nanoparticles and proposed the conception of flexible interfacial layer, which was consideredwww.elsevie

18、r.com/locate/apsuscApplied Surface Science 254 (2007) 1456–1462* Corresponding author. Tel.: +86 391 6634601; fax: +86 391 6634601. E-mail address: xxm326@yahoo.com.cn (Z. Zhang).0169-4332/$ – see front matter # 2007 Els

19、evier B.V. All rights reserved. doi:10.1016/j.apsusc.2007.07.014more than the dynamic force, in order to ensure good contact between the probe and the sample.2.4. Mechanical characterizationThe tensile testing of the com

20、posites was conducted at a crosshead speed of 20 mm/min on a DY35 universal testing machine (Adamel Lhomargy, France). The notched Charpy impact strength was measured with ZBC1400-2 (Sans, China) at a rate of 2.9 m/s. Al

21、l these tests were conducted at room temperature and an average value of least five repeated tests was taken for each composite.3. Results and discussion3.1. Characteristics of silicas isolated from PA66/nano- SiO2 compo

22、sitesTGA spectra of AMS, PA66 and products of six extraction treatments were conducted, as shown in Fig. 1. It is clear that the total weight loss of AMS is the lowest (<19%), whereas that of neat PA66 nearly achieves

23、 100%. The weight loss of the extraction products reduces gradually with the increase of the extraction cycles. After three extraction cycles, the weight loss of isolated silica is almost unchanged (about 34%), which is

24、still higher than that of AMS. The matrix PA66 weakly attached to silica surface is almost completely removed by the extraction treatment with formic acid. Fig. 1 also shows that the weight loss of the extraction product

25、s is close to that of AMS before 400 8C. However, in the temperature range of 400–500 8C, TGA curves of all extraction products, similar to that of PA66, show a rapidly decrease trend, which is ascribed to the decomposit

26、ion of adhered PA66 in silica surface. These clearly indicate that the strongly adhered PA66 layer have been formed on the silica surface.Fig. 2 shows the FTIR spectra of PA66, AMS and silica isolated from nanocomposites

27、 (SIN). The adsorption peaks at 1390, 1560 cm?1 appearing in the spectrum of AMS represent the stretching vibration of C–H and bending vibration of N–H.Additionally, the adsorption peak at 2936 cm?1 shows that long alkyl

28、 chain is present in the silica surface. These indicate that the silane coupling agent is adhered to the surface of silica. It is possible that the –OH groups of nano-SiO2 surface reacts with silanol groups of APS genera

29、ted by hydrolysis to form modified nano-SiO2 with organic compounds on the surface. In comparison with AMS, SIN shows the characteristic bands of PA66 at 1640, 1545 cm?1 (amide bands) and 2940, 2865 cm?1(C–H bands). Espe

30、cially, the appearance of N–H characteristic band at 3310 cm?1 (hydrogen bonds) further indicates that there is a considerable amount of PA66 chains adhered on AMS surface [7]. Owing to SIN treated by six extraction cycl

31、es, thus, it is reasonable to conclude that PA66 chains have been chemically grafted to the AMS surface. To examine the interaction between PA66 and AMS from another angle, we used XPS to characterize the surface group i

32、nteraction. Fig. 3 shows the Si 2p spectrum of AMS and SIN, C 1s and O 1s spectrum of neat PA66, AMS and SIN. Since there are a large number of CH2 groups in the PA66/AMS system, the binding energy of C 1s (284.8 eV) is

33、used as the reference. In Fig. 3(a), the Si 2p peak of AMS at 102.9 eVis assigned to Si 2p in Si-alkyl from the modifier, which is lower than that of SiO2 (103.5 eV). As the alkyl groups (NH2(CH2)3–) grafted to silica su

34、rface are strong electron donor groups, the conjoint silica atoms become electron-rich and result in a shift of the peak of Si 2p towards low binding energy direction. The Si 2p spectrum of SIN is quite different from th

35、at of AMS, which consists of two peaks at 103.5 and 102.9 eV. The appearance of SiO2 peak indicates that only a part of modifiers is grafted to silica surface by chemical bonding, but another part of modifiers perhaps en

36、wraps silica nanoparticles by physical absorption. It is main reason that the peak profile of SiO2 does not occur in the Si 2p spectrum of AMS. After AMS are compounded with PA66 matrix and extracted by formic acid, the

37、modifiers attached to the surface of silica nanoparticles by physical absorption are removed because of stronger interaction with PA66 chains. So the intensity of SiO2 peak increases and the peak profile Fig. 1. TGA curv