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Sayed Ibrahim Faculty at Technical University of Liberec, Department of Textile Technology Ph.D from Technical University of Liberec, Czech Republic Research Interest: Textile Technology and Quality Control Topic Characterization of Basalt Filaments in Longitudinal Compression

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CHARACTERIZATION OF BASALT FILAMENTS IN LONGITUDINAL COMPRESSION Jiří Militký, Vladimír Kovačič, Sayed Ibrahim Textile Faculty, Technical University of Liberec 461 17 Liberec, Czech Republic

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(approx. 8000 students) Faculty of Mechanical Engineering Textile Faculty Faculty of Education Faculty of Economics Faculty of Mechatronics Faculty of Architecture Technical University of Liberec

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Staff 120 teachers 1.MSc Studies (technology, material engineering, clothing) 800 2.BSc Studies (chemistry, marketing, design, mechanics, clothing) 600 3.Part time studies (textile technology) 60 4. Ph.D. (technology, material engineering, clothing) 60 Technical University of Liberec Textile Faculty

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Basics of textile engineering Fibers are the fundamental and the smallest elements constituting textile materials. The mechanical functional performance of garments are very much dependent on the fiber mechanical and surface properties, which are largely determined by the constituting molecules, internal structural features and surface morphological characteristics of individual fibers. Scientific understanding and knowledge of the fiber properties and modeling the mechanical behavior of fibers are essential for engineering of clothing and textile products. Molecular properties Fiber Properties Yarn Properties Fabric properties Fiber Structure Yarn Structure Fabric Structure Garment Structure Demands of using textiles in industrial application are very high and risk should be minimum i.e. precise characterization

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OUTLINE Basalt rocks Fibers formation Basic properties Compressive creep Strength statistics Tempering Textile structures Fibrous fragments

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Basaltic rocks Basalt is generic name for solidified lava which poured out the volcanoes Basalt is 1/3 of earth Crust Basaltic rocks are melted approximately in the range 1500 – 1700 C. When this melt is quickly quenched, it solidificated to glass like nearly amorphous solid. Slow cooling leads to more or less complete crystallization, to an assembly of minerals. Augite Plagioclase Olivine

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Basalt composition Chemical composition: silicon oxide SiO 2 (optimal range 43.3 – 47 %) Al 2 O 3 (optimal range 11 – 13 %) CaO (optimal range 10 – 12 %) MgO (optimal range 8 – 11 %) Other oxides are almost always below 5 % level Essential minerals plagiocene and pyroxene (augite) make up perhaps 80% of basalts

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Fiber Forming Process Similar to E-glass forming Except: Only one material, crushed rock No “flux” like boric oxide added for processing Higher melting temperature 1400 C + vs. 1200 C Harder to process, but better properties (Silane-based sizing agent is added to facilitate post processing) Basalt Furnace 1) Crushed stone Silo, 2)Loading station, 3) Transport system, 4)batch charging station, 5) Initial melt zone, 6) Secondary contrlled heat zone, 7) Filament forming, 8) Sizing applicator, 9) Strand formation, 10) Fiber tensioning, 11) Winding

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Filaments formation Classical procedure Heat transfer from walls to center High power (4 kWh/kg) Long pre heating 8 hours Spinneret materials (Platinum, rhodium) Microwave heating Heat transfer from center to walls Low power (1 kWh/kg) Short pre heating 3 hours Spinneret materials (ceramics) Melt after 5 min at 1300 o C

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Properties of Basalts Basalts are more stable in strong alkalis that glasses. Stability in strong acids is low Basalt products can be used from very low temperatures (about –200 C) up to the comparative high temperatures 700 – 800 C. At higher temperatures the structural changes occur.

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Basalt Glass Comparison PropertyBasaltE-glass Diameter[ m] 8.639 - 13 Density[kgm -3 ]27332540 Softening temp. [ C] 960840 Typical composition of basalt fiber vs. E-glass fiber Chemical components Basalt Weight % E-Glass Weight % SiO 2 (silica)5855 Al 2 O 3 (alumina)1715 Fe 2 O 3 (ferric oxide)100.3 CaO818 MgO43 Na2O2.50.8 TiO 2 1.1- K2OK2O0.80.2 B2O3B2O3 -7 F-0.3 standard E-glass fibres from non-alkali glass (to 1% alkali), manufactured at 1550 o C Manufacturing cost is between E-glass and S- glass Sio 2 Al 2 O 3 CaO MgO B 2 O 3

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Applications The basalt-reinforced PP composite meets disposal requirements without incinerator contamination issues

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Samples Preparation The marbles and filament roving are prepared. From marbles the thick rods were prepared by grinding. The roving contained 280 single filaments are used. Mean fineness of roving was 45 tex.

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Fibers Strength The cumulative probability of fracture F(V, ) depends on the tensile stress level and fiber volume V. F(V, ) = 1 - exp(- R( )) The specific risk function R( ) for Weibull distribution (conditional failure function) R( ) = [( - A)/B] C A is lower strength limit, B is scale parameter and C is shape parameter model (WEI 3) Shape parameter, location parameter, scale parameter.

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Strength distributions For brittle materials A = 0 (model WEI 2). Kies more realistic risk function (model KIES) R( ) = [( -A)/(A1- ) ] C Here A1 is upper strength limit. For brittle materials A = 0 (model KIES2). Phani (model PHA5) R( ) = [( -A)/B1] D / [(A1- )/B ] C ). Gumbell model (GUM) R( ) = exp[( -A)/(B)]

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Statistical analysis Main aim of the statistical analysis is specification of R( ) and parameter estimation based on the experimental strengths ( i ) i=1.....N. Based on the preliminary computation it has been determined that for basalt fibers strength the Weibull distribution is suitable

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Testing The individual basalt fibers removed from roving were tested. The loads at break were measured under standard conditions at sample length 10 mm. Load data were transformed to the stresses at break i [GPa] Sample of 50 stresses at break

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Maximum likelihood estimation When i i=1,...N are independent random variables with the same probability density function f( ) = F’( i, a) the logarithm of likelihood function has the form ln L = ln f(( i, a) The a are parameters of corresponding risk function. The MLE estimators a* can be obtained by the maximization of ln L(a).

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Parameter estimates ModelA [GPa]B [GPa]C [-]ln L(a*) WEI30.06410.2301.37033,50 WEI2-0.3011.82929.164 The differences between three and two parameters Weibull distribution are identified by the values of maximum likelihood function ln L(a*). The three-parameter Weibull distribution was selected as suitable for glass and tempered basalt samples as well

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Failure mode Modes of fracture - scanning electron microscopy. Untreated BasaltLongitudinal view

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Mechanism of fracture Surface is very smooth without flaws or crazes Fracture occurs due to nonhomogenities in fiber volume (probably near the small crystallites of minerals) glass basalt

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Thermal exposition I Tempering temperature 50, 100, 200, 300 o C was used. Time of exposition 60 min. Thermal exposition influence on the ultimate mechanical properties and dynamic acoustical modulus (DMA) has been evaluated. tensile strength [N.tex-1] deformation to break [%] dynamic acoustic modulus [Pa] (determined from sound wave spread velocity in the material) For 300 o C tempering only results statistically significant drop of strength and dynamic acoustical modulus. The changes of these properties are based on the changes of crystalline structure of fibers.

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Resonance frequency technique (RFT) Acoustic Pulse Method (APM) Sample

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Thermal exposition II Basalt filament roving tempered at T T = 20, 50, 100, 200, 300, 400 and 500 o C in times t T = 15 and 60 min. The dependence of the roving strength on the temperature exhibits two nearly linear regions. One at low temperature to the 180 o C with nearly constant strength and one up to the 340 o C with very fast strength drop

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Thermal exposition III 1. Tempered basalt fibers from roving were tested. 2. The apparatus based on the torsion pendulum principle was used. (fiber of length l o hanged with pendulum period P and amplitude A, successive oscillations were measured, the shear modulus of circular fiber is calculated) 3. The shear modulus G =11-21 GPa is comparatively high. The prolongation of tempering leads to high drop of G. lolo

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Thermal exposition IV Fragility - ratio of critical loop diameter Dc and fiber diameter d Fr = Dc / d critical loop diameter - by deformation of basalt loop under microscope to failure temperature 50, 150, 250, 350 o C was evaluated time of exposition 60 min In accordance with assumption are fragilities increasing function of tempering temperature the quality or state of being easily broken or destroyed

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Thermo mechanical analysis (TMA) In TMA the dimensional changes are measured under defined load and chosen time Special device TMA CX 03RA/T has been used Sample is placed on the movable holder (in oven) connected with displacement sensor, which measures dimensional changes

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Thermal expansion Dependence of basalt rod height on the temperature was measured.( heating rate 10 deg min -1, compressive load 10 mN). The coefficients of thermal expansions a for region below and above T g L = L g + a 1 *(T - T g )for T below T g L = L g + a 2 *(T - Tg)for T above T g Parameter estimates: T g = 596.3 o C, a 1 = 4.9 10 -6 deg -1, a 2 = 19.1 10 -6 deg -1. rate of material expansion as a function of temperature DMA

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Compressive creep For the basalt rods and linear composites the dependence of sample height L on the time t were measured. L = L p + L 1 exp (-k 1 * t) + L 2 exp(-k 2 * t) Parameters L p, L 1, L 2, k 1 and k 2 estimated by LS The maximum dilatation D = L 1 + L 2 Half time of dilatation t 1/2 (it is time for which is dilatation equal to L p + (L 1 + L 2 )/2.

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Compressive creep parameters T [ o C] D[mm] t 1/2 [s] D [mm] t 1/2 [s] 30 50 100 250 300 0.003 0.028 0.053 0.035 - 145.1 36.90 29.80 41.10 - 0.015 - 0.008 - 0.042 16015 - 21.30 - 51.7

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Non-isothermal compressive creep The responses of basalt to the compressive loads under non-isothermal conditions were investigated from creep type experiments. The load was 200 mN. For the basalt rod the dependence of sample height L on the temperature T (increased linearly with time t )were measured. Starting temperature was T o = 30 o C and rate of heating was 10 o C/min. For avoiding the initial The dilatation d i = L o – L has been recorded

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Data Smoothing The experimental points were smoothed by Reinsch smoothing spline (parameter s = 1) deltatation temperature

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Creep model I From isothermal experiments is deduced that the rate of creep only is markedly temperature dependent. The rate of height changes can be expressed by differential equation K is the rate constant is sample height in equilibrium. Function f(.) is creep rate model.

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Creep model II The classical reaction kinetics the creep rate can be expressed in the form where n is constant (order of reaction). For n=1 the simple exponential model of creep (rate process of first order) results. Temperature dependence of the creep rate constant K

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Creep model III In non-isothermal conditions it is assumed that temperature dependent is rate constant only By the formal integration of this eqn. for exponential type model (n = 1) the following relation results

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Creep model IV For the case of linear heating during creep is valid Symbol T o denotes initial temperature and G(x) is the integral where is rate of heating

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Approximation of integral Simple and precise approximation of temperature term has the form The relative error of approximation is for E/RT<7 under 1%.

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Parameter estimation These should be estimated from experimental data. The nonlinear regression have to be used. More simple is to use rate equation for first order model combined with Arrhenius dependence in the linearized form Application of this equation requires knowledge of L and computation of creep rate

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Creep rate The rate of creep curve can be derived from Reinsch smoothing procedure (s=1)

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Estimation of activation parameters on 1/T (in absolute temperature scale) was created. From parameters of this fit: preexponential factor K o = 0.04772 activation energy of creep E = 2.203 kJ/mol The dependence of

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Creep discussion More precisely it will be necessary to use general order of rate process and investigate n as well Thermally stimulated creep is successfully used in the area of polymers. In non-polymeric solids where compressive creep is due to rearrangements of molecular clusters and structural reordering are rate models quite useful.

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Longitudinal compressive modulus Linear composite (C) from the phase of Basalt fibers (K) and epoxy resin matrix (E). Both phases are deformed elastically The volumetric ratio of Basalt fibers is K. The simple rule of mixture E c is creep modulus of linear composite E E is creep modulus of epoxy resin,E K is creep modulus of basalt fibers

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Modulus estimation The K was estimated by the image analysis value K = 0,9 was obtained. The modulus E C at individual temperatures F = 200 mN is load, A K = 20.725 mm 2 is cross sectional area K(10) is deformation under compressive creep in time t = 10 s. By the same way the modulus E E was estimated from the compressive creep curve of pure epoxy resin

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Estimated moduli T [ o C] E K (Basalt) [GPa] E C (Composite) [GPa] E E (Resin) [GPa] 25112.27105.4140.5129 5095.25687.4917.5076 100114.084108.57558.9869 20099.7690.9511.6239

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Textile structures The basalt filament yarns were prepared with fineness 40x2x3. Knits and sewing thread were created. Utilization of basalt for preparation of knitted fabric was without problems During sewing tests the basalt yarns were frequently broken due to its brittleness. The composite basalt thread coated by PET was prepared.

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Sewing threads properties PropertyBasalt/PET fineness [tex]283.3 ± 1.6 yarn twist 1[m -1 ]208 ± 7.4 yarn twist 2[m -1 ]400 ± 9.8 yarn twist 3 [m -1 ]180 ± 5.6 break strength [N.tex -1 ]0.34 Break deformation [%]2.3 ± 0.2 abrasion resistance[cycle]180 ± 49.8 breaks at sewing test0

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Emitted particles analysis Some characteristics of the basalt fibers are similar to the asbestos. Since the mechanisms for asbestos carcinogenicity are not fully known it cannot be excluded that basalt fibers may also be hazardous to health. Thus there is a need for analysis of fibrous fragment characteristics in production and handling in order to control their emission.

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Fragmentation The weave from basalt filaments was used. The fragmentation was realized by the abrasion on the propeller type abrader. Time of abrasion was 60 second. It was proved by microscopic analysis that basalt fibers are not split and the fragments have the cylindrical shape.

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Analysis Fiber fragments were analyzed by the image analysis, system LUCIA M. The fragments shorter that 1000 m were analyzed. Results were lengths L i of fiber fragments. For comparison the diameters D i of fiber fragments were measured as well.

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Fragments length Basic statistical characteristics fiber fragments lengths are mean value L M = 230.51 m standard deviation L = 142.46 m skewness g 1 = 0.969 kurtosis g 2 = 3.97 These parameters show that the distribution of fiber fragments is unimodal and positively skewed.

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Fragments diameter Basic statistical characteristics of fragments diameters are: mean value D M = 11.08 m standard deviation L = 2.12 m skewness g 1 = 0.641 kurtosis g 2 = 2.92 Because the mean value of fiber fragment diameter is the same as diameter of fibers no splitting of fibers during fracture occurs.

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Fragmentation conclusion It is known, that from point of view of cancer hazard the length/diameter ratio R is very important. For basalt fiber fragments is ratio R = 230.51/11.08 = 20.8. Despite of fact that basalt particle are too thick to be respirable the handling of basalt fibers must be carried out with care.

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