Results and discussion - Part B
CONDITIONS - PART B
JANA ĎURFINOVÁa, PAVEL KOŠTIALb, IVAN RUŽIAKb, ZORA JANČÍKOVÁb, MARTINA FARKAŠOVÁb, LUBOŠ KRIŠŤÁKc, JANKA
JURČIOVÁd, SOŇA RUSNÁKOVÁe, and IVAN LETKOe
a Slovak University of Ttechnology in Bratislava, The Faculty of Chemical and Food Technology,Radlinskeho 9, Bratisava 912 37, b VŠB-Technical University of Ostrava, Faculty of Metallurgy and Material Engineering, 17. listopadu 15/2172, 70833 Ostrava-Poruba, Czech Republic, Department of Mate-rials Engineering, c Technical University in Zvolen, Faculty of Wood Science and Technology, T.G.Masaryka 24, 960 53 Zvolen, Slovak Republic, d Saar Gummi Slovakia spol. s r.o., Gumárenska 397/21, Dolné Vestenice 972 23, Slovak Repub-lic, e Tomas Bata University in Zlín, Faculty of Technology, T.
G. Masaryka 275, 762 72 Zlín, Czech Republic pavel.kostial@vsb.cz
Abstract
In this contribution we present measurements of external and internal tire temperature as well as the internal tire
pres-sure by complex system for the simultaneous contact less measurement of these values (CTPA). The measurement is fully automatic, controlled by a personal computer and in-stalled “in situ” on the car. The global position system, which is connected to a PC, further allows us to measure also the car speed in synchronized regime with other measured parame-ters. All external temperatures under investigation were inde-pendently tested by other contact thermometers.
Results and discussion - Part B
The same kind of dependence for the left wheel (sample A) is in the Fig. 5, to demonstrate decrease of measured out-door temperature in this case caused by left tire release. In the Fig. 6 (B) and 7(C) are right wheel temperature-speed pendences for tires of other producers. On the Fig. 8 is a de-pendence of internal tire temperature versus time. Due to relatively small pressure changes we don’t present the pres-sure/speed changes which are also registered by the CTPA system.
The results of “peak” outdoor (Text.Max) right wheel temperature as well as the onset time of internal temperature (tonset) increase are in Table I (see also the Fig. 9). This Table also contains fitted value of experimental relaxation time τexp.
Values of τexp are mean values of fitted data.
From experimental outdoor temperature decay curves we can determine the experimental “relaxation time”. In every case it depends on the heat capacity and sample density as material constants (for convective heat transport characterized by constant h relaxation time is possible to express in the form τ=ρ.cp.V/h.S). The slowest tire temperature decay is observed for sample A (τexp=76,2), which is accompanied by tire overheating (Text.Max=338,8 ° C). The onset time (tonset=60s) signals quick energy transfer (also through tire sidewall) from rubber composite to the air inside a tire. As we said this fact is probably caused by improper breaker angle.
Different situation is for samples B and C .The smallest value of relaxation time (τexp=53,8) was observed for the sam-ple B and a τexp=65,6 for the sample C. In both cases the tire overheating is sufficiently smaller than in the case A which is seen on values of Text.Max =236,4 for the sample B and 236,3 for the sample C.
Fig. 5. Left wheel time-temperature-speed curves for sample A Left wheel temperature versus speed
0
13:48:00 13:55:12 14:02:24 14:09:36 14:16:48
Temperature, speed
Sensor4 Sensor5 Sensor6 Speed
Table I
The data of maximum external tire temperatures, as well as the onset time of internal temperature increase tonset and ex-perimental relaxation time
Conclusion
CTPA is useful, fully automatic instrument for “in situ“
monitoring of both internal and external tire temperatures and tire pressure. The CTPA system allowes the easy data match-ing and offer constructors interestmatch-ing information about tire temperature trends in real driving conditions.
REFERENCES
1. Smartire 2010. SmarTire for Commercial Vehicles, http://
www.smartire.com/cv.
2. SPEED-WIZ 2010. Chassis Calculations, http://
www.speed-wiz.com/calculations/ chassis/index.htm.
3. TireChek 1999. TireChek Tire Pressure Monitor, http://
mb-soft.com/tirechek/.
4. Autoware Inc. 2009. Tire Temperature Analyzer, http://
www.auto-ware.com/ software/ tta/tta.htm.
5. BorgWarner BERU Systems GmbH 2010. Tire Safety Systems TSS – The Tire Pressure Control System, http://
www.beru.com/english/produkte/tss.php.
6. Koštial P., Hutyra J., Kopal I., Mokryšová M.: 10th Inter-national Conference: Progress in materials engineering.
2005, 29.
7. Koštial P., Hutyra J., Kopal I., Mokryšová M., Klabník M., Žiačik P.: Chem. Listy 23, 99 (2005).
8. Koštial P., Mokryšová M., Šišáková J., Mošková Z., Rusnáková S.: Int. J. Thermophysics 30, 334 (2009).
9. Mokryšová M., Koštial P., Kučerová J., Mošková Z.:
Exp. Tech. 33, 33 (2009).
Fig. 9. The internal temperature-time curve
Fig. 8. Internal temperature-speed curves for sample A Internal temperature versus speed - sample A
0 10 20 30 40 50 60 70
13:48:00 13:55:12 14:02:24 14:09:36 14:16:48
Temperature, speed
Left front wheel Right front wheel Right back wheel Left back wheel Speed Fig. 7. Right wheel time-temperature-speed curves for sample C
Right wheel temperature versus speed - sample C
0 50 100 150 200 250
11:38:24 11:45:36 11:52:48 12:00:00 12:07:12
Temperature, Speed
Sensor1 Sensor2 Sensor3 Speed
Fig. 6. Right wheel time-temperature-speed curves for sample B Right wheel temperature versus speed - sample B
0 50 100 150 200 250
10:48:00 10:55:12 11:02:24 11:09:36 11:16:48 11:24:00
Temperature, speed
Sensor1 Sensor2 Sensor3 Speed
Sample A B C
Text(MAX)[°C] 338,8 236,4 236,3
tonset[s] 60 289 1281
τexp [s] 76,2 53,8 65,6
P-42
INFLUENCE OF CROSS-SECTION MODIFICATION OF PP FIBRES ON THE END-USED PROPERTIES JOZEF RYBAa, ANNA UJHELYIOVÁa, ĽUBA HORBANOVÁ, and PETER MICHLÍKb
a Department of Fibres and Textile Chemistry, Institute of Polymer Materials, Faculty of Chemical and Food Technol-ogy, Slovak University of Technology in Bratislava, Radlin-ského 9, 812 37 Bratislava, Slovakia, b Research Institute for Man-Made Fibres, a.s., Štúrova 2, 059 21 Svit, Slovakia jozef.ryba@stuba.sk
Abstract
Shape of cross-section of the fibres has significant influ-ence on end-used properties of fibres which are used for textile or technical applications. This work is focused on an evaluation of the influence of this varied fibre geometry on different proper-ties and characteristics of polypropylene (PP) fibres.
Introduction
Ones of the main end-used properties of textile materials are mechanical and transfer properties (heat, humidity and air).
The transfer properties of fibres correspond mainly with their surface properties. The transfer properties of fibres are mainly re-lated to their geometry. The cross-section and longitudinal fibre geometry is defined by the following characteristics such as shape and size of fibre surface, volume of fibre, measuring surface of fibres and capillary system between the fibres and yarns. A great variety of fibre profiles with different surfaces and sur-face prop-erties can be reached during the technological conditions of syn-thetic fibre spinning and drawing by profiling in cross-section and longitudinal direction1-3.
Shaped fibres with special or strongly irregular profiles are very promising. They are manufactured with spinnerets with the appropriate profile of holes4. The shaped fibres can be used to develop new kinds of textiles and low-melting knits, since the irregular profile sharply increases the frictional forces between filaments. In addition, the high covering power of the shaped fibres reduces materials consumption for the articles.
For evaluation of shaped fibre characteristics are used following relations:
PN circumference of cross-section, SN surface of cross-section, SY surface of circumscribed circle, PY circumfer-ence of circumscribed circle, R radius of circumscribed circle, r radius of inscribed circle, AD surface of hollows, AV surface of fibre
Triangular and three-pronged — “trilobal” — are the most frequently encountered shape. Triangular fibres with a flat surface can be used to manufacture articles with a “luster effect” due to high light reflection by their individual seg-ments. Fibres with a flat (more precisely, oval) section also have a luster effect. In addition, high flexibility is characteris-tic of these fibres due to the lower moment of inertia of the flat section in flexure in comparison to round sections4.
This article deals about influence of the cross-section shape of the polypropylene fibres onto above mentioned end-used properties.
Experimental
Materials used
For the preparation of non-modified (nPP) and modified PP (mPP) fibres was used polypropylene Tatren HT 1810 with MFI = 20.9 g/10 min from Slovnaft a.s., Slovakia and micronized inorganic filler (6.4 wt.%). From these materials were prepared undrawn fibres with circle and five pointed star shape cross-section and modified by inorganic filler on the laboratory spinnig machine. Next, the undrawn PP fibres have been to drawn to the drawing ratios λ = 3 and 4.
Method used
Mechanical properties were measured on INSTRON 1122 and evaluated according to STN EN ISO 1973, 5079, 2062 standard methods for evaluation of mechanical pa-rameters.
For evaluation of shaped PP fibre characteristics was used optical microscope Olympus BX51 equipped with CCD camera and software analySIS FIVE version 5.0 (build 1120).
For evaluation of water vapour sorption of PP fibres was used gravimetric analysis. Samples were dryed at 80 °C for 1 hour in drying chamber. After that samples were puted into glass vessel with saturate solution of NH4NO3 (relative hu-midity over this solution is 65 % at 20 °C) for 96 hours. After this period the samples were weighing. In the next step sam-ples were dryed in drying chamber at 105 °C for 3 hours and weigh again.
Content of water vapour (CWV) sorption was calculated on the backround of this formula:
were m weight of the fibre with water vapour sorption in equilibrium state (after 96 hours), mo weight of the fibre after drying.
Degree of branching: R=PN2/SN
Filling degree: Z=SN/SY
Degree of
segmenta-tion: Se=PN/PY
Degree of deformation: D=R/r
Coefficient of fullness
(for hollow fibres): FP=(1-AD)/AV
(1)
% 100
0 0
m
m CWV m
Results
Mechanical properties of non-modified and modified PP fibres are shown in Table I and Table II. Tenacity at the break of PP fibres modified by micronized inorganic filler is lower in comparison with non-modified PP fibres at both drawing ratios λ=3 and 4. This is caused by particle size of micronized inorganic filler, which decrease the sufficiency of drawing of polymer matrix. This type of inorganic filler has no reinforce-ment effect on PP fibre matrix. However tenacity at the break of non-modified and modified PP fibres with cross-section shape of five pointed star is higher than tenacity at the break of non-modified and modified PP fibres with circle shape cross-section. The micronized inorganic filler due to decrease of tenacity at the break of PP fibres with cross-section shape of five pointer star in comparison with the non-modified PP fibres with the same cross-section shape. This confirms the theoretical knowledge, that the addition of micronized filler to the oriented polymer matrix decreases their mechanical prop-erties. These all statements are analogical for Young’s modulus as well as elongation at the break.
Next part of end-used properties of non-modified and modified PP fibres is shown in Tables III and IV. Cross-section area (A) of circle shape cross-Cross-section of modified PP fibres is higher in comparison with cross-section area of non-modified PP fibres. This is caused by present of micronized inorganic filler (lower filament diameter homogenity). Cross-section area of the PP fibres with five pointed star cross-section shape is higher than cross-cross-section area of the PP fibres with circle cross-section shape. This can cause the different cooling and crystallization of PP melt flow from various pro-files of hole at the same conditions of preparation.
Degree of branching (R) and degree of segmentation (Se) of the non-modified and modified PP fibres with five pointed star cross-section shape decrease with increasing drawing ratio. Filling degree (Z) of the non-modified and modified PP fibres with five pointed star cross-section shape slightly encrease with higher drawing ratio.
All calculated parameters (R, Z, Se) obtained by optical microscopy for fibres with circle cross-section shape are equal 1.
Content of water vapour sorption of modified PP fibres is higher than sorption of non-modified PP fibres. This is also caused by present of micronized inorganic filler which can invade surface homogenity of each filament of the fibre.
These all statements are analogical for both types of cross-section shape of the fibres and drawing ratios.
The PP fibres with the circle shape cross-section as well as with five pointed star cross-section shape at the lower drawing ratio (λ=3) have higher segmentation of their profile and it provide the higher water vapour sorption of these fi-bres.
Conclusion
On the backround of experimentally obtained results it can be concluded that:
change of cross-section geometry from circle to five pointed star have positive influence onto tenacity and Young’s modulus of the non-modified and modified PP fibres,
Table II
Fineness (Td), tenacity (σ) and elongation (ε) at the break, Young‘s modulus (E) of the non-modified and modified PP fibres with drawing ratio λ=4
Sample Td
[dtex] σ
[cN/dtex] ε
[%] E
[cN/dtex]
nPP-circle 6,1 3,4 117 35,3
mPP-circle 6,2 3,0 95 32,5
nPP-star 5,9 4,2 140 35,0
mPP-star 6,4 3,6 122 27,0
Table I
Fineness (Td), tenacity (σ) and elongation (ε) at the break, Young‘s modulus (E) of the non-modified and modified PP fibres with drawing ratio λ=3
Sample Td
[dtex] σ
[cN/dtex] ε
[%] E
[cN/dtex]
nPP-circle 6,0 2,8 155 24,8
mPP-circle 6,3 2,6 139 23,4
nPP-star 6,0 3,4 158 26,2
mPP-star 6,2 3,0 185 21,8
Table III
Cross-section area (A), degree of branching (R), filling degree (Z), degree of segmentation (Se), content of water vapour (CWV) of the non-modified and modified PP fibres with draw-ing ratio λ=3
Sample A [m2] R Z Se CWV
(wt.%)
nPP-circle 535 1,05
mPP-circle 670 1,15
nPP-star 604 24,8 0,63 1,09 1,21
mPP-star 940 20,9 0,67 1,05 1,30
Table IV
Cross-section area (A), degree of branching (R), filling degree (Z), degree of segmentation (Se), content of water vapour (CWV) of the non-modified and modified PP fibres with draw-ing ratio λ=4
Sample A [m2] R Z Se CWV
(wt.%)
nPP-circle 560 0,61
mPP-circle 705 0,70
nPP-star 630 23,9 0,64 1,11 0,83
mPP-star 811 20,7 0,69 1,06 0,99
cross-section area of the fibres with five pointed stars cross-section shape is higher than cross-section area of circle cross-section shape fibres and have positive influ-ence on content of water vapour sorption.
Modificated fibres like these are applicable for technical fabric and for improving of the other types of materials like concrete for example.
This work was supported by the VMSP-P-0007-09 and VEGA 1/0444/09.
REFERENCES
1. Jambrich M.: Fibres Text. East. Eur. 6, 33 (1998).
2. Murárová A.: Chemical Papers. 47, 356 (1993).
3. Murárová A.: Chimvolokno 3, 56 (1993).
4. Perepelkin K. E.: Fibre Chem. 37, 123 (2005).
P-43
COMPARISON OF INJECTION MOLD