THE PROPERTIES OF REINFORCED POLYPROPYLENE COMPOSITES HAVING DIFFERENT DISTRIBUTED FIBERS

Wielkość: px

Rozpocząć pokaz od strony:

Download "THE PROPERTIES OF REINFORCED POLYPROPYLENE COMPOSITES HAVING DIFFERENT DISTRIBUTED FIBERS"

Katarzyna Zając
5 lat temu
Przeglądów:

1 KOMISJA BUDOWY MASZYN PAN ODDZIAŁ W POZNANIU Vol. 28 nr 3 Archiwum Technologii Maszyn i Automatyzacji 28 ZOLTÁN BUDAI, ZSOLT TIBA, GYÖRGY DEÁK THE PROPERTIES OF REINFORCED POLYPROPYLENE COMPOSITES HAVING DIFFERENT DISTRIBUTED FIBERS The paper deals with reinforcing of polypropylene copolymers with homopolymer fibers. There are several methods to produce reinforced polypropylene composites. One of them is to feed homopolymer fibers into the molten plastic in the mixing chamber and after that specimens can be cut away from this copolymers. An other method of producing specimens is that oriented homopolymer fibers are pressed between two semifinished polipropylene copolymer plates. Specimens produced in this ways were tested by authors with tensile-testing instrument and the influence of the different distribution of fibers on the mechanical properties of copolymer has been evaluated. Key words: polypropylene homopolymer fiber, randomly distributed fibers, oriented fibers 1. INTRODUCTION In several Eastern European countries the economy is quickly growing, plastic demand, especially that of polypropylene, is rising with very high rate. In Hungary TVK Co. Ltd. (Tiszaújváros) is the only polyethylene, polypropylene producer. They produce polypropylene homopolymer, random copolymers and block/copolymers with ethylene. The production and usage of polypropylene is dynamically growing, because of the excellent properties wide applicability and relatively low cost of PP (almost as good as PVC). Recently much attention has been paid to the modification of properties of PP by making composites [1 5]. The main aim of these blending is to improve the impact strength especially at low temperatures. Because of the easier dispose of PP compared to PVC, the medical equipment users often ask how plasticized PVC can be replaced with PP. Our aim was to investigate the possibility of the use of PP fiber to produce composites with PP matrices. We planed to make PP composites containing Coll. Prof. Dr. hab PhD University of Debrecen Centre for Agricultural Sciences and Engineering Faculty of Engineering. Dr. University of Debrecen Faculty of Science Department of Applied Chemistry.

2 126 Z. Budai, Z. Tiba, G. Deák randomly mixed short PP fibers and we also wanted to make PP composites containing oriented PP fibers. The homopolymer fibre is a trimming at the production of clingfilm getting from the manufacturer in the given size and form. 2. EXPERIMENTAL We used PP fiber (ribbon) mm H284F type. This polymer has a softening point of 15 o C. All the matrices used have a softening point of 13 o C (of course it is less than melting point), so there is a 2 o C gap in the softening range. The Table 1. shows the softening point and the MFI of the fiber and the matrices. If the temperature of R889 type polipropylene copolymer during the production is raising above 15 o C the homopolymer fiber would melt in the matrice. The kneading torque was not measured. All polymers are made by TVK Co., Hungary. The softening points and the melt flow indices of the fiber and the matrices Temperatura mięknienia oraz wskaźniki ciekłego włókna i matryc Table 1 PP type Softening point MFI (23 o C, 21.6 N) R o C 11 g/1 min R 451 F 13 o C 6.5 g/1 min R o C 2. g/1 min R o C.4 g/1 min H 284 F 15 o C 18 g/1 min 3. METHODS The preparation of mixed PP composites were made in a Brabender typemixing chamber at 14 C for 5 min. The matrix was melted and the fiber was introduced into the mixing chamber for about 1 5 minutes. The mixing chamber was stopped, sample was taken from which plates were pressed while the sample was hot. Next day the dumbbell specimen were cut out and tested. The preparation of oriented fiber containing composites were the following: Thin plates were made from the matrix and the fibers were fixed on the surface with the use of a soldering iron then plate-fiber-plate sandwiches were pressed together at 14 C for 1 minutes. The pressing temperatures of all the plates were 14 C. Specimens were cut out for testing. The Figure 1. shows the dumbbell specimen having two oriented fibers.

3 The properties of reinforced polypropylene 127 Fig. 1. Specimen with two oriented fibers (the measures are in mm) Rys. 1. Próbka z dwoma zorientowanymi włóknami (wymiary w milimetrach) 4. INSTRUMENTS A Brabender type of mixing chamber was used for mixing together the matrices and the fiber. A Fontijne type table press was used for molding plates and the mechanical testing was done by using a computer controlled Instron 42 mechanical testing instrument. 5. RESULTS AND DISCUSSION Mechanical properties of the starting materials can be seen in Table 2. Other properties of the fibre (e.g. shrinkage ability) were not tested which can significant influence the thermal stability of the composite. Mechanical Properties of the Starting Materials Właściwości mechaniczne użytych do badań materiałów Table 2 Polymer Stress at yield [MPa] Strain at yield [%] Modulus [MPa] R R 451 F R R H 284 F plate H 284 F fiber The polymers used for matrices have stress at yield lower than 3 MPa, but the fiber has a higher value. So we hoped that the fiber could improve the mechanical properties of matrices.

4 128 Z. Budai, Z. Tiba, G. Deák A typical stress-stain curve of the randomly mixed PP composite can be seen in Figure 2. The yielding point is at about 1% of strain and the composite breaks soon after yielding. Slight improvement of mechanical properties can be observed only. Fig. 2. A Typical Stress-Strain Curve for the Composite Having Randomly Distributed PP Fibers Rys. 2. Typowe krzywe rozciągania kompozytu z losowo rozłożonymi włóknami PP The Figure 3. shows the dependence of stress at yield versus fiber content. The trend-line shows none or just a slight increase with increasing fiber content Stress at Yield [MPa] Fiber Content [%] R 359 R 452 F R 654 Fig. 3. Stress at Yield vs Fiber Content (Randomly distributed fibers) Rys. 3. Naprężenia przy granicy plastyczności w zależności od składu losowo rozłożonych włókien

5 The properties of reinforced polypropylene 129 The Figure 4. shows the dependence of strain at yield on fiber content of composites. The strain at yield decreases with the increasing fiber content of the composites. 6 5 Strain at Yield [%] R 359 R 451 F R Fiber Content [%] Fig. 4. Strain at Yield vs Fiber Content (Randomly distributed fibers) Rys. 4. Odkształcenie przy granicy plastyczności w zależności od składu losowo rozłożonych włókien Figure 5. shows several typical stress-strain curves for the composites having oriented fibers. The line % shows the behavior of the native polymer. When we added 4% of oriented fiber a good increase in stress at yield can be observed. Additional 4% of oriented fiber (altogether 8%) doubles the strength of the polymer composite. We found that we can predict the stress at yield value of composite with the use of the addition rule and the stress at yield value of pure starting materials. Figure 6 and 7 show the dependence of the stress and strain at yield on the fiber content. Stress and strain at yield increase with the increasing fiber content. Fig. 5. Typical Stress-Strain Curves for the Composites Having Oriented Fibers Rys. 5. Typowe wykresy rozciągania kompozytu o zorientowanych włóknach

6 13 Z. Budai, Z. Tiba, G. Deák 7 Stress at yield [MPa] Fiber Content [%] Fig. 6. Stress at Yield vs Fiber Content (Oriented fibers) Rys. 6. Naprężenia przy granicy plastyczności w zależności od składu zorientowanych włókien 3 Strain at Yield [%] Fiber content [%] Fig. 7. Strain at Yield vs Fiber Content (Oriented fibers) Rys. 7. Odkształcenia przy granicy plastyczności w zależności od składu zorientowanych włókien 6. SUMMARY The mechanical properties of composites were investigated. The composites were made from a polypropylene homopolymer fiber and several random polypropylene co- and polyethylene homopolymers. Although very small difference exists in softening behavior of the matrix and the fiber (13 and 15ºC) we were able to ensure the temperature difference and in this way we could keep the fiber in its original form. The PP fiber and PP-copolymer composites show an increasing stress at yield by increasing the fiber content. A significant increase in stress at yield was observed by increasing the oriented fiber content.

7 The properties of reinforced polypropylene 131 REFERENCES [1] Calimberti M., Giannini U., Albizzati E. et al., J. Mol. Catal. A: Chem., 1995, 11, 1 1. [2] Chung T.C., Lu H.L., Li C.L., Polymer Int., 1995, 37, [3] Lu Yan, Zhu Meifang, Zhang Yu, Chen Yanmo, Petrochem. Techn.&Application., 1999, 17(3), s [4] Peckstadt J.-P., Chem. Fibers Int., 1997, 47(5), 342. [5] Saheb D.N., Jog J.P., Advences in Polymer Technology, 1999, 18, 351. [6] Xu G., Lin S., Macromol. Sci. Rev., Macromol. Chem. Phys., Part C, 1994, 34, Praca wpłynęła do Redakcji Recenzent: prof. dr hab. inż. Tomasz Sterzyński WŁAŚCIWOŚCI KOMPOZYTÓW POLIPROPYLENOWYCH O RÓŻNIE ROZŁOŻONYCH WŁÓKNACH S t r e s z c z e n i e Artykuł dotyczy wzmacniania kopolimerów polipropylenowych włóknami homopolimerowymi. Istnieje kilka metod wytwarzania wzmocnionych kompozytów polipropylenowych. Jedną z nich jest dodawanie homopolimerowych włókien w stanie ciekłym do komory mieszania, po czym wycina się próbki z kopolimeru. Inna metoda wytwarzania próbek polega na tym, że zorientowane włókna homopolimerowe są prasowane między dwoma półwykończonymi płytkami kopolimeru polipropylenowego. Próbki wytwarzane w ten sposób były testowane przez autorów na maszynie wytrzymałościowej, co pozwoliło na ocenę wpływu różnego rozłożenia włókien na właściwości mechaniczne kopolimeru. Słowa kluczowe: homopolimerowe włókno polipropylenowe, losowo rozłożone włókna, włókna zorientowane

Podobne dokumenty

Zakopane, plan miasta: Skala ok. 1: = City map (Polish Edition)

Zakopane, plan miasta: Skala ok. 1:15 000 = City map (Polish Edition) Click here if your download doesn"t start automatically Zakopane, plan miasta: Skala ok. 1:15 000 = City map (Polish Edition) Zakopane,