材料科學(xué)與工程專業(yè)外文翻譯--納米二氧化硅對共連續(xù)形態(tài)的聚丙烯聚烯烴彈性體共混物的影響（原文）

1、Effect of nanosilica on the co-continuous morphology of polypropylene/polyolefin elastomer blendsS.H. Lee a, M. Kontopoulou a,*, C.B. Park ba Department of Chemical Engineering, Queen’s University, Kingston, ON K7L3N6, C

2、anada b Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S3G8, Canadaa r t i c l e i n f oArticle history:Received 25 October 2009Received in revised form8 January 2010Accepted 11

3、 January 2010Available online 18 January 2010Keywords:NanocompositesThermoplastic Olefin blendsCo-continuous morphologya b s t r a c tThis paper reports the effect of nanosilica (SiO2) on the morphology of co-continuous

4、immisciblepolypropylene (PP)/polyolefin elastomer (POE) blends. The unfilled blends display phase inversion anda co-continuous structure at a ratio of 50/50 PP/POE by weight. Upon addition of SiO2 in the presence ofmalea

5、ted PP compatibilizer a finer structure, consisting of elongated POE particles dispersed within thePP phase is obtained. This transformation is associated to the presence of finely dispersed SiO2 particlesthat are locali

6、zed exclusively within the PP matrix. The impact properties, flexural and Young’s moduli ofthe blends increase significantly, pointing to a synergistic effect arising from the presence of the rein-forced PP phase, contai

7、ning high amounts of the finely dispersed elastomeric phase.? 2010 Elsevier Ltd. All rights reserved.1. IntroductionPolymer blending is used extensively to develop new materials that exhibit a favorable combination of pr

8、operties, depending on the selection of blend components. As most polymers are immiscible, their blends form multi-phase systems with various morphologies and synergistic properties. The nature of the structures created

9、during processing depends upon several factors, such as the material properties of the neat polymers (interfacial tension, rheological properties), processing conditions (shear rate and mixing time) and the relative amou

10、nts of material used. The type of morphology determines to a large extent the physical properties of the blends, thus proper control of the morphology plays a key role in inducing desirable properties to the blends. The

11、droplet/matrix morphology, which imparts favorable impact and other mechanical properties, as in the case of high-impact poly- styrene and polypropylene, has been widely studied. Co-contin- uous morphologies have also dr

12、awn significant interest [1], because they have the potential to widen the application range for polymer blends due to their interconnected nature [1–4]. Co-continuous morphologies exhibit interesting properties rele- va

13、nt to conductivity or permeability owing to the percolation of the two phases. A wide range of techniques to determine the co-continuity region and the resulting structures, includingsolvent extraction [5–9], microscopy

14、[10–14] and rheology [10,15– 17] have been described in the literature. Extensive research during the last decade has confirmed the influence of nanoparticle addition on the morphology of polymer blends. It is now widely

15、 accepted that in the presence of nano- particles, such as organoclays and nanosilica, the droplet-matrix morphology shifts toward a finer dispersion of the minor phase. The selective localization of the nanofiller in on

16、e of the phases, typically the matrix or the interphase, seems to be key to explaining this phenomenon. Possible explanations that have been offered include compatibilizing effects due to filler adsorption at the interfa

17、ce of the two polymers, resulting in a reduction in the interfacial tension [18–20]. However these mechanisms are obviously not dominant when the filler resides in the matrix [21]. In that case it has been speculated tha

18、t exfoliated clay platelets or well dispersed nano- particles surroundedbyan immobilized bound layerof polymer may hinder particle coalescence by acting as physical barriers [22–24]. On the other hand, there are quite a

19、few reports of nanofillers favoring the formation of co-continuous structures in various blend combinations [25–30]. In some cases, the formation of a double- percolated structure, where conductive fillers such as carbon

20、 nanotubes are dispersed in one of the co-continuous phases is desirable and is done on purpose, since it can result in favorable conductive properties [31,32]. It is therefore clear that, apart from the obvious effect t

21、hat nanofillers have on the physical properties of the blends, they can also generate a more indirect effect, through the control of their morphology.* Corresponding author. Tel.: þ1 613 533 3079; fax: þ1 613 5

22、33 6637.E-mail address: marianna.kontopoulou@chee.queensu.ca (M. Kontopoulou).Contents lists available at ScienceDirectPolymerjournal homepage: www.elsevier.com/locate/polymer0032-3861/$ – see front matter ? 2010 Elsevie

23、r Ltd. All rights reserved.doi:10.1016/j.polymer.2010.01.018Polymer 51 (2010) 1147–1155four blocks of kneading discs having positive (þ30?), neutral (90?), and negative (?30?) staggered angles and two left-handed sc

24、rew elements, to provide good dispersive and distributive mixing. The screw speed was 200 rpm, resulting in an extrusion rate of 2.5 kg/h. The temperature profile in the extruder from the feeding section to the die was 6

25、0 ?C–200 ?C–205 ?C–205 ?C–210 ?C–210 ?C–200 ?C for all blends. These conditions were selected because prior work has shown that they provide the optimum dispersion of nanosilica. Silica was added to the 50/50 PP/POE blen

26、ds at loadings ranging from 1 to 5 wt%. PP-g-MAn was used to improve the dispersion of SiO2 resulting in a PP matrix composition of PP/PP-g-MAn 90/10. Antioxidant (0.3 phr) was added to all formulations.2.3. Mechanical p

27、ropertiesTensile properties were measured using an Instron 3369 universal tester, at crosshead speeds of 50 mm/min. Dumbbell- shaped specimens were cut with a Type V die according to ASTM D638 from 1.5 mm thick sheets, w

28、hich were prepared by compression molding of the compounded samples at approxi- mately 200 ?C using a Carver press. Flexural tests were performed according to ASTM D790, proce- dure B, at a speed of 13.65 mm/min. Rectang

29、ular bars of dimensions 127 ? 12.7 ? 3.2 mm were produced by compression molding at 200 ?C. Notched Izod impact tests were carried out using an Instron BLI impact tester at room temperature according to ASTM D 256. Speci

30、mens of dimensions 64 ?12.7 ? 3.2 mm were prepared bycompression molding at 200 ?C. At least 5 specimens were tested for each sample and the average values are reported.2.4. Microscopy and image analysisThe state of disp

31、ersion of the filler was assessed by TEM imaging, using an FEI Tecnai 20 instrument. Ultra-thin sections were cryomicrotomed using a Leica ultra microtome and stained in RuO4 vapor to enhance the phase contrast between t

32、he PP and elastomer phases. For SEM observations, samples were first hot pressed at 190 ?C, 2 tons for 1 min, then immersed in liquid nitrogen for 5 min before brittle fracture. The elastomer phase was etched in n-heptan

33、e for 2.5 h at 80 ?C. The etched surfaces were observed on a JEOL JSM-840 scanning electron microscope. The SEM images were analyzed by using the Sigma Scan Pro image analysis software to estimate the average diameters o

34、f the dispersed elastomer phase on the basis of the Ferret diameter, which is calculated based on the estimated area, A, of the particles, according to:D ¼ffiffiffiffiffiffi 4A pr(1)00.10.20.30.40.50.60.70.80.910 10

35、 20 30 40 50POE content (wt.%)Average domain size, µmFig. 3. Average POE domain size as a function of POE content. Error bars represent thestandard deviation.Fig. 4. Percentage of continuity of the POE phase as a fu

36、nction of POE content.0204060801001201400 10 20 30 40 50 60 70 80' G e c a f r e t n i ) a P (POE content (wt%)Fig. 5. G’interface as a function of POE content at 0.04 rad/s and 190 ?C.1010010001000010 100 1000 10000

37、 Shear rate (s -1)Shear viscosity (Pa.s)Fig. 6. Shear viscosities of blend components as a function of shear rate at 200 ?C. (A)PP; (,) POE; (B) PP/PP-g-MAn; (6) PP/PP-g-MAn/SiO2 2 wt%; (þ) PP/PP-g-MAn/SiO2 10.5 wt%