2005年--外文翻譯--無規(guī)共聚聚丙烯在不同試驗參數(shù)下對其機械性能的影響（節(jié)選）

1、<p>　　中文3100字,2000單詞，10500英文字符</p><p>　　出處：Sahin S, Yayla P. Effects of processing parameters on the mechanical properties of polypropylene random copolymer[J]. Polymer Testing, 2005, 24(8):1012-1021.&l

2、t;/p><p>　　本科生畢業(yè)設計（論文）外文譯文</p><p>　　學 院 </p><p>　　專 業(yè) </p><p>　　導 師 </p><p>　　學 生

3、 </p><p>　　學 號 </p><p>　　Effect of testing parameters on the mechanical propertiesof polypropylene random copolymer</p><p>　　Senol Sahin, Pasa Yayla*</p&g

4、t;<p>　　Mechanical Engineering Department, Engineering Faculty, Kocaeli University, 41040 Kocaeli, Turkey Received 24 January 2005; accepted 2 March 2005</p><p><b>　　Abstract:</b></p&

5、gt;<p>　　The effects of temperature on the impact resistance and hardness of polypropylene random copolymer are studied for a wide range of temperatures. The variations in the mechanical properties with a wide ran

6、ge of strain rates are also evaluated. Finally, the variations in mechanical properties as a function of time after production are studied. </p><p>　　Keywords: Polypropylene random copolymer; Mechanical prop

7、erties; Storage time; Strain rate</p><p>　　1. Introduction</p><p>　　There is a vast literature on processing, morphology, testing and ultraviolet (UV) degradation of polypropylene(PP) [1–3]. How

8、ever, the literature lacks results on the effects of storage time, outdoor ageing time and the addition of different master batches at different ratios on the mechanical properties. This may be connected to the fact that

9、 those investigations are very rigorous and time-consuming. For these reasons, the aim of this paper is to study the influence of testing parameters on th</p><p>　　2. Experiments</p><p>　　2.1. M

10、aterials</p><p>　　The polymer used in this study is a natural colour PP-R, produced by Borealis s. a, trade name RA 130E, and supplied in granular form. The properties of the polymer are given in Table 1.<

11、;/p><p>　　2.2. Specimen preparation</p><p>　　A specially designed injection mould was used to produce test samples. The configuration of the moulded test samples is depicted in Fig. 1.All the test

12、samples were injection moulded on a ERATFE 130/95 injection moulding machine. Table 2 shows the specification, set parameters of the machine and the moulding conditions. Unless otherwise mentioned, before testing all the

13、 samples were conditioned at room temperature for a period of 30 days.</p><p>　　2.3. Tensile tests</p><p>　　The tensile test samples were dumbbell-shaped with dimensions of 156*1014 mm, complyin

14、g with ISO 527-1 (1993) standard. Tensile tests at various speeds were carried out on the samples. A Z wick Z10, screw-driven universal tensile/compression testing machine equipped with a data acquisition system , was ut

15、ilised to carry out the tensile tests. Unless otherwise mentioned, a 50 mm/min test speed was used. For strain rate effect investigation, a wide range of speeds from 1 to 1000 mm/min were used. </p><p><b

16、>　　Table 1 </b></p><p>　　Typical properties of polymer used in this study</p><p>　　specimens for each test series, average values for yield stress（Y）, tensile strength（Mpa）, elastic mo

17、dulus（E）, strain-to yield（Y）, and strain-to-break, 3B, were deduced using the testing program of the controlling computer</p><p>　　2.4. Charpy impact tests</p><p>　　Impact fracture energy is an

18、 important parameter characterizing toughness of materials. Impact values represent the total ability of the material to absorb impact energy, which is composed of two parts: (a) the energy required to break bonds, and (

19、b) the energy consumed in deforming a certain volume of the material. With conventional impact testing equipment (without instrumentation), it is practically impossible to measure separately these two parts. Instrumented

20、 impact testing provides valuabl</p><p>　　The geometry of the Charpy impact test samples was rectangular with dimensions of 80!10!4 mm, conforming to the ISO 179/1eA (2000) standard. A single-edge 458 V-shap

21、ed notch (tip radius 0.25 mm, depth 2 mm) was milled in the bars with a fly-cutter using a milling machine.</p><p>　　A series of Charpy impact tests were carried out for a wide range of temperatures accordin

22、g to ISO 179/1eU (2000). For setting the test temperature, a mixture of liquid nitrogen and acetone at different ratios was used. The test samples were kept in the cooling medium for at least 30 min before testing.</p

23、><p>　　The Charpy impact tests of the notched specimens were conducted at a wide range of temperatures ranging from K 75 to 85 8C, employing a creast Instrumented Charpy Impact Tester (Code 6545/000) at an impa

24、ct speed of 2.93 m/s. The Charpy impact energy evaluation was based on the linear elastic fracture mechanics (LEFM) analysis to determine impact strength of materials as proposed by Plati and Williams [6]. Charpy impact

25、energy Cv is given by</p><p>　　where U is the absorbed energy by the sample, B and D are the width and thickness of the samples, respectively, and F is the sample geometry-dependent calibration factor. Beari

26、ng in mind the advantages of instrumented Charpy impact tests, both the crack initiation energy, which is consumed up to the maximum force, and the total impact energy, which is the conventional Charpy impact energy, dis

27、sipated during whole impact process, were calculated.</p><p>　　2.5. Hardness test</p><p>　　Hardness is defined as the resistance of a material to deformation, particularly permanent deformation,

28、</p><p><b>　　Table 2</b></p><p>　　Specification and set parameters of the injection moulding machine used in this study</p><p>　　indentation or scratching. In general, t

29、he most widely used methods to measure hardness are Rockwell and Shore. The Rockwell method is usually used for harder materials , The Shore (or Durometer) method, regulated by ISO 868 (2003), has scales for both softer

30、rubbers and plastics.</p><p>　　In this work, Shore D hardness tests were performed at different temperatures using a Z wick 3100 Shore D Durometer hardness tester. All results are the average of three measur

31、ements.</p><p>　　3. Results and discussion</p><p>　　3.1. Tensile tests</p><p>　　The tensile behaviour and ultimate mechanical properties are very important characteristics of semi-c

32、rystalline polymers. These macroscopic properties are known to very closely depend on the strain rate, thus an understanding of strain rate dependence of their deformation behaviour is important for encouraging their wid

33、e use in engineering and structural applications [7]. Strain rate has a complicated and dramatic effect on materials deformation processes because the energy expended during plast</p><p>　　sample, (2) large

34、deformation in the neck, which transforms the micro-spherulitic structure to fibrillar structure, and lastly (3) post-neck deformation of the fibrillar structure. In general, in the neck, the polymeric material softens d

35、rastically for a very short period, which is associated with a decrease of plastic modulus. However, as the neck develops and exceeds a limiting zone, the morphology changes to that of a fibrillar structure with increase

36、 in plastic modulus, termed as strain-hard</p><p>　　Typical stress–strain curves of the PP-R samples tested at different crosshead speeds are given in Fig. 2. The test samples were not broken at 600% elongat

37、ion at crosshead speeds up to 25 mm/min, but for the higher test speeds, the samples were ruptured at lower % elongation and had a value of about 38% at crosshead speed of 1000 mm/min. At lower test speeds, the PP-R samp

38、les formed a very marked and stable neck with a wide stress-whitening zone; as the test proceeded, the necked zone extended t</p><p>　　The effects of cross head speeds on the variations in‘yield stress’, ‘yi

39、eld strain’ and ‘elastic modulus’ are given in Figs. 3–5, respectively. The behaviour of these properties with log(crosshead speed) was linear and suggested that, like other semi-crystalline polymers, the mechanical prop

40、erties of PP-R is also very strain rate-sensitive. It has been pointed out that the slope in these figures might vary from one semi-crystalline material to another and could be a good indication to define the</p>

41、<p>　　3.2. Impact tests</p><p>　　The effect of temperature on the variation of force–time signal obtained from instrumented Charpy impact tests were depicted in Fig. 6, showing remarkable change in natu

42、re of the force–time signal as the temperature changes. Fig. 6 shows that up to about 25℃, almost all of the energy is</p><p>　　consumed at crack initiation stage, and the energy consumed during crack propag

43、ation stage becomes visible for temperatures above 50℃. At temperatures above 75℃, the specimens were partly fractured, while below this temperature they were completely fractured.</p><p>　　The variation of

44、Charpy impact energy with temperature is given in Fig. 7, giving relatively constant impact strength between K75 and 0℃. and then the impact strength rapidly increases with increasing temperature. After 90℃, it becomes i

45、mpossible to break the sample into two. The phenomenon of characteristic brittle–ductile transition starts after 0℃, indicating the fact that the impact strength deteriorates dramatically as the temperature approaches fr

46、om higher values to 0℃. These results are p</p><p>　　attention as the pipes get rather fracture-sensitive at lower temperatures.</p><p>　　The Charpy crack initiation and crack propagation fractu

47、re resistance evaluation are given in Fig. 8. The figure shows that up to the lower transition temperature of 0℃, about 90% of impact energy is consumed to initiate fracture, but the trend changes as the test temperature

48、 increases,</p><p>　　implying that crack propagation energy is higher than the crack initiation energies for temperatures above 50℃. For higher temperatures, the crack initiation consumes only about 35% of t

49、he total impact energy.</p><p>　　4. Conclusions</p><p>　　This paper outlines experimental results from tensile tests at different crosshead speeds and instrumented Charpy impact tests on notched

50、 samples of polypropylene random copolymer over a wide range of temperatures. Special attention was focused on the changes in the tensile properties over a long period of storage after injection. Regarding the effects of

51、 on the mechanical properties of polypropylene random copolymer, the following conclusions could be drawn:</p><p>　　(1) The tensile properties of the materials are fairly rate sensitive. The properties such

52、as the yield stress, elastic modulus and yield strain of the material increase with strain rate. The variations of these properties with log (crosshead speed) were linear and it is envisaged that the slope in these figur

53、es might very from one semi-crystalline material to another and could be a good indicator to define the strain rate dependency of semi-crystalline polymeric materials.</p><p>　　(2) The Charpy impact crack in

54、itiation and propagation resistances of the material are rather sensitive to the test temperature. For lower temperatures of up to 0℃, relatively brittle behaviour has been observed. The effect of an increase in temperat

55、ure becomes visible after 0 and above 85℃ the material becomes too ductile to break. </p><p>　　(3) The Shore D hardness of the natural PP-R material is diminished with increasing temperature. The decrease in

56、 hardness becomes more remarkable after the lower transition temperature of 0℃.</p><p>　　5 References</p><p>　　[1] E.P. Moore (Ed.), Polypropylene Handbook: Polymerisation, Characterisation, Pro

57、perties, Applications, Hanser/Gardner, New York, 1996, p. 113.</p><p>　　[2] J. Karger-Kocsis (Ed.), Polypropylene—An A–Z Reference, Kluwer, Dordrecht, 1999.</p><p>　　[3] J. Karger-Kocsis, Polypr

58、opylene: Structure and Morphology, Chapman & Hall, London, 1995.</p><p>　　[4] M.P. Manahan Sr., C.A. Cruz Jr., H.E. Yohn, Instrumented impact testing of plastics in limitation of test methods for plastic

59、s, in: J.S. Peraro (Ed.), ASTM STP 1390, American Society for Testing and Materials, West Conshohocken, PA, 2000.</p><p>　　[5] P.S. Leevers, P. Yayla, M.A. Wheel, Charpy and dynamic fracture testing for rapi

60、d crack propagation in polyethylene pipe, Plast. Rubber Compos. Process. Appl. 17 (1992) 247–253.</p><p>　　[6] E. Plati, J.G. Williams, Determination of the fracture parameters of polymers in impacts, Polym.

61、 Eng. Sci. 15 (1975) 470–477.</p><p>　　[7] R. Gensler, C.J.G. Plummer, C. Grein, H.-H. Kausch, Influence of the loading rate on the fracture resistance of isotactic polypropylene and impact modified isotacti

62、c polypropylene, Polymer 41 (10) (2000) 3809–3819.</p><p>　　[8] A. Dasari, R.D.K. Misra, On the strain rate sensitivity of high density polyethylene and polypropylene, Mater. Sci. Eng. A 358 (2003) 357–371.&

63、lt;/p><p>　　[9] A.J. Peterlin, Molecular model of drawing polyethylene and polypropylene, J. Mater. Sci. 6 (6) (1971) 490.</p><p>　　[10] A. Dasari, S.J. Duncan, R.D.K. Misra, Atomic force microscop

64、y of scratch damage in polypropylene, Mater. Sci. Technol. 18 (10) (2002) 1227–1234.</p><p>　　[11] J. Fiebig, M. Gahleitner, C. Paulik, J. Wolfschwenger, Ageing of polypropylene: processes and consequences,

65、Polym. Test. 18 (1999) 257–266.</p><p>　　無規(guī)共聚聚丙烯在不同試驗參數(shù)下對其機械性能的影響</p><p>　　Senol Sahin, Pasa Yayla*</p><p>　?。瀑Z埃利大學工學系機械工程系，科賈埃利 41040 土耳其日期2005年1月24日，接受2005年3月2日）</p><p

66、>　　摘要：研究一定溫度范圍內(nèi)溫度對無規(guī)共聚聚丙烯（PP-R）的抗沖擊性能和硬度的影響；研究了材料的拉伸性能與應變率的關系，在很寬的應變率范圍內(nèi)其多項力學性能受應變率的影響較大；最后研究了PP-R成型后的儲存時間與其機械性能的關系。</p><p>　　關鍵詞：無規(guī)共聚聚丙烯，力學性能，存儲時間，應變率</p><p><b>　　1.引言 </b></p

67、><p>　　有大量關于聚丙烯（PP）處理，形態(tài)，測試和紫外線（UV）的降解的文獻[1-3]。然而，其中缺少關于存儲時間對PP的影響、戶外老化時間和填加不同比率填料對PP力學性能的影響的結論。這可能需要聯(lián)系實際，它的研究是非常嚴密和耗費時間?；谶@些原因，本文的目的是，研究成型無規(guī)共聚聚丙烯在不同貯存時間的力學性能和熱性能</p><p><b>　　2．實驗</b>&l

68、t;/p><p><b>　　2.1．材料 </b></p><p>　　在這項研究中所使用的聚合物是由Borealis s. a公司生產(chǎn)的一種天然無規(guī)共聚聚丙烯（PP-R），其商標名稱為RA 130E，它呈顆粒的形式。其性能如表1。</p><p><b>　　2.2．樣品制備</b></p><p>

69、;　　測試樣品采用特別設計的注塑模具生產(chǎn)。測試樣本性能如圖1所示。所有的測試樣本都使用ERATFE 130/95注塑機成型。表2為此款注塑機的結構圖。首先設置儀器參數(shù)和成型條件，，所有樣本在測試前均需在室溫條件下保存30天。除非特殊要求</p><p>　　表1 本研究所使用聚合物的典型特性</p><p><b>　　2.3．拉伸試驗 </b></p>

70、<p>　　拉伸試驗的測試樣本尺寸均為156*10*4mm，遵從ISO 527-1（1993）標準。設定不同速度對樣本進行拉伸試驗。拉伸儀器的名稱為A Z wick Z10，利用通用螺桿驅動的拉伸/壓縮試驗機的數(shù)據(jù)采集系統(tǒng)設備來進行拉伸試驗。我們使用50毫米/分鐘的測試速度，除非另有提及。研究應變率效應，所使用的速度范圍是從1到1000mm/min,伸長計被利用來測定其彈性模量。試驗在溫度為23℃之下進行。每組樣本至少進行三

71、次試驗，然后采用計算機測試程序推導出屈服應力、抗張強度、彈性模量、應變屈服的平均數(shù)。</p><p>　　2.4．懸臂梁式?jīng)_擊試驗 </p><p>　　沖擊斷裂能是表征材料韌性的重要參數(shù)。沖擊值可用來表現(xiàn)材料吸收沖擊能量的能力，他是由兩部分組成：(a) 斷裂所需的能量，（b）一定量的材料在一定形變之下所需消耗的能源。</p><p>　　傳統(tǒng)的沖擊試驗設備（沒有儀

72、表），實際上是無法將這兩個部分分開的。沖擊試驗儀器提供了斷裂過程中所涉及的能源的信息，對于材料的裂紋開裂和裂紋延伸所需的能力可以提供很好的評價，而傳統(tǒng)的沖擊試驗設備是不可能實現(xiàn)這點的。許多材料，裂紋缺口是發(fā)生在前夕或在最大負荷時形成。因此，這合理和近似的確定了當裂紋開裂時所需的能量是最大的[4]。同樣，峰后的能源，被定義為當材料為了抵抗裂紋擴展所需的能量。在許多工業(yè)應用中，研究溫度對沖擊強度的影響是很有意義的，而且它引起了工業(yè)與學術界高

73、度重視[5]。 </p><p>　　懸臂梁式?jīng)_擊試驗測試樣品的尺寸為80*10*4mm的矩形，符合ISO 179/1eA（2000）標準。用銑床高速切割刀切一個單獨的V形切口（尖端半徑0.25mm，深2mm），按照ISO 179/1eA（2000年）標準。在一個很寬的溫度范圍內(nèi)進行了一系列懸臂梁式?jīng)_擊試驗。設置測試溫度，使用不同比例的液態(tài)氮和丙酮的混合物，在實驗前測試樣本至少保存在冷卻介質里30分鐘。</

74、p><p>　　對處理過的缺口樣本進行了一個的沖擊速度為2.93m/s，溫度從75℃至85.8℃的懸臂梁式?jīng)_擊試驗，首先將懸臂梁式?jīng)_擊試驗機（Code 6545/000）的脈沖速率設定為2.93m/ s，沖擊能量評價是基于線彈性斷裂力學（LEFM）分析的，普拉蒂和威廉姆斯提出怎樣確定材料的沖擊強度 [6]。懸臂梁式?jīng)_擊能量Cv值由下式給出</p><p>　　其中U是指樣本被吸收能量，B和D分

75、別為樣本的寬度和厚度，F(xiàn)是樣本幾何依賴校準因子。沖擊試驗儀器是很好的儀器設備，無論是消耗最大能源的裂紋萌生，還是傳統(tǒng)的懸臂梁式?jīng)_擊能量的總沖擊能量，它整個過程都可以計算出。</p><p><b>　　2.5．硬度測試 </b></p><p>　　硬度是指材料的抗變形能力，特別是指永久變形缺口或刮痕。一般來說，測量硬度最普遍的方法為Rockwell and Shor

76、e。Rockwell方法通常用于比較硬的材料， Shore的（或硬度計）方法，符合ISO 868（2003年）的標準，它已運用于軟橡膠和塑料的測試。Shore硬度是使用Shore硬度計在不同溫度下進行測試。其結果是三個測量值的平均值。</p><p>　　表2 本研究成型注塑機的規(guī)范和設置參數(shù)</p><p><b>　　3．結果和討論</b></p>

77、<p><b>　　3.1.拉伸試驗</b></p><p>　　半結晶聚合物的拉伸能量和力學性能是非常重要的特性。這些宏觀特性非常依賴于應變率，因此研究他們的應變率影響因素對于工程和結構的應用是非常重要的[7]。材料變形過程中有著復雜及引人注目的應變率，因為變形過程中的能源消耗主要是因為熱量消散。在等溫圖中，在更高的溫度的圖與非關聯(lián)負荷率較低時，可觀察到更多的負載[8]。一般來說

78、，半結晶聚合物的拉伸試驗分為三個階段 [9,10]：（1）測試樣品的微球粒狀結構化，（2）微球粒狀結構變換為纖維狀結構，（3）最后，后頸部的纖維結構的變形。一般來說，高分子材料在短期內(nèi)徹底軟化與塑性模量的減少有關。然而，當它繼續(xù)變長和超過一個限制區(qū)時，塑性模量增強的纖維結構形態(tài)變化，稱為應變硬化。</p><p>　　無規(guī)共聚聚丙烯（PP-R）樣品在不同切速度下的應力應變曲線如圖2。在切速度為25mm/min時測

79、試樣本沒有超過600%的伸長率，但當切速度更高時，測試樣本伸長率變低，并且已破裂，當切速度為1000mm/min時，伸長率約38％。在較低的切速度下，PP-R樣本可形成非常明顯和穩(wěn)定的寬的應力致白區(qū)域；在測試的過程中，縮小的區(qū)域在整個測試測量的破裂點延長到非常大的變形值。在這個階段，應給應變硬化一個逐步增加的壓力直到樣本破裂。由于切速度的增加應力致白區(qū)域變小，在高速時，標準長度的其余部分沒有塑性變形。</p><p&

80、gt;　　切速度的變化對‘屈服應力’，‘屈服應變’和‘彈性模量’的影響分別如表3-5。這些性能的關系都是線性的，像其他半結晶聚合物，應變率對PP-R力學性能的影響是非常大的?？梢灾赋觯@些圖表的斜率會因材料的不同而不同，另外它很好的確定了應變率對材料的影響力[11]。</p><p><b>　　3.2 沖擊試驗 </b></p><p>　　懸臂梁式?jīng)_擊試驗儀器得到

81、的不同溫度下時間與力的關系如圖6所示。當溫度變化時，力-時間關系信號也顯示出顯著的變化，如圖6顯示，溫度增加至25℃時，幾乎所有的能源都消耗在裂紋萌生階段，當溫度超過50℃時，能源消耗在裂紋擴展階段變得明顯。在溫度高于75℃時，測試樣本部分斷裂，而低于此溫度，測試樣本則完全斷裂</p><p>　　懸臂梁式?jīng)_擊能量與溫度的關系如圖7所示，溫度從-75℃和0℃沖擊強度相對不變，當溫度繼續(xù)升高時其沖擊強度快速增加。當

82、溫度到達90℃以后，其沖擊強度不會在增加而測試樣本被拉斷。0℃以后材料變成脆韌的特點，它表明一個事實，當溫度非常接近于0時，沖擊強度急劇惡化。 這些結果從兩個方面來看是很有重要的現(xiàn)實意義的，首先，在實際應用中PP-R管可以運用于低于0℃的環(huán)境中，其次，運輸和在較低溫度下的管道安裝是可能的。因此，當管道在較低溫度下容易斷裂時，這兩點需要特別被重視。 </p><p>　　懸臂梁式和裂紋擴展的斷裂性如圖8。這個圖表表

83、明，當溫度接近較低溫度0℃時，有大約90％的沖擊能量消耗在裂紋萌生階段，但由于測試溫度有升高的趨勢，使得當溫度大于50℃時裂紋擴展所需能量高于裂紋萌生所需能量。在較高溫度下裂紋萌生僅消耗約35％的能量。</p><p><b>　　4 結論 </b></p><p>　　本文概述了PP-R缺口在很寬的溫度范圍內(nèi)，在不同的切速度下的懸臂梁式?jīng)_擊試驗和拉伸試驗的實驗結果。

84、特別值得注意的是成型后的PP-R放置時間長之后，其拉伸性能發(fā)生變化。關于不同試驗條件對PP-R的機械性能的影響，得出以下結論：</p><p>　?。?）材料的拉伸性能受應變率的影響。如屈服應力，彈性模量和屈服應變都隨材料的應變速率增加而遞增的特性。這些性能的變化呈線性關系，設想在這些圖表的斜率很可能從一個半結晶材料到另一個，它可能是一個良好的指標來定義半結晶聚合物材料的應變率。</p><p

85、>　?。?）PP-R的懸臂梁式?jīng)_擊裂紋萌生和裂紋擴展對溫度是相當敏感，對于趨近于較低溫度0度時其比較脆弱，當溫度大于0℃時，隨著溫度的上升其變化程度是顯著的， 當溫度大于85℃時，測試樣本變得太長以至于被拉斷。 </p><p>　?。?）隨著溫度的降低天然PP-R材料的Shore硬度在逐漸變小。當溫度低于0℃時其硬度下降得更加顯著。</p><p><b>　　5 參考文

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