Physico-chemical characterization and comparison of fluorinated commercial Ski-Waxes.

Transcription

1 SKI-WAX Physico-chemical characterization and comparison of fluorinated commercial Ski-Waxes. Luca Fambri, Riccardo Ceccato, Emanuela Callone and Denis Lorenzi Department of Industrial Engineering, University of Trento, Italy

2 SUMMARY Object of this research is the physical chemical characterization and the comparison of some of the main commercial ski-waxes for alpine competitions. In particular different commercial producers have been considered (Briko-Maplus, Soldà, Rode and Toko), and for each producer, skiwaxes with different fluorine content were compared, i.e. Perfluorinated (F), High Fluorine (HF), Low Fluorine (LF) and No Fluorine (NF) products. Wax composition was studied by infrared spectroscopy (FTIR) and NMR spectroscopy (in particular 1H and 13C). Thermal analysis through differential scanning calorimetry (DSC) evidenced the melting interval and enthalpy, and the following crystallization kinetics in direct dependence on the wax composition. Rheological testing was performed at various temperature and shear conditions in order to compare the relative viscosity of the correspondent composition. Moreover it is well known that during applications various fluorinated by-products determine contamination of ski-men; and at this purpose the thermogravimetric analysis (TGA) will show the differentiated thermal stability both in dynamic heating and in prolonged isothermal treatment up to 150 C in order to simulate the application conditions.

3 Ski-Wax Selection i) Different fluorine content products have been selected, i.e. Perfluorinated (F), High Fluorine (HF), Low Fluorine (LF), No Fluorine (NF). ii) Different color in dependence on the type of snow, have been compared: Yellow, Red, Orange, Violet, Blue. iii) Different ski-waxes were purchased from commercial producers : Briko-Maplus, Soldà, Rode and Toko.

4 Ski-Wax Characterization Wax composition was studied by Infrared Spectroscopy (FTIR) and solid state Nuclear Magnetic Resonance NMR spectroscopy (in particular 1H and 13C). Thermal analysis through Differential Scanning Calorimetry (DSC) evidenced the melting interval and enthalpy, and the following crystallization kinetics in direct dependence on the wax composition. Rheological testing was performed on HF-ski waxes at various temperature and shear conditions in order to compare the relative viscosity of the correspondent composition. Thermogravimetric Analysis (TGA) showed the differentiated thermal stability both in dynamic heating and in prolonged isothermal treatment up to 150 C in order to simulate the application conditions, and to evaluate possible fluorinated by-products that could determine contamination of ski-men.

5 FTIR Spectroscopy -1 Ski-Waxes were studied through Infrared Spectroscopy (FTIR) by using an ATR-FTIR spectrometer Spectrum One (Perkin Elmer) in the range cm -1. are compared in the following.

6 FTIR Spectroscopy -2 Wax composition of high fluorine ski-wax (HF) can be easily compared by Infrared Spectroscopy (FTIR), considering the representative peaks of C-F ( cm -1 ) and those of C-H at ( cm -1 and cm -1 ).

7 NMR Spectroscopy Solid state NMR spectroscopy is a powerful technique for the acquisition of detailed information on the molecular structure and packing See Extended Abstract and Posters - E. Callone et al. Characterization of Fluorinated Ski-waxes through NMR Spectroscopy and Rheological Analysis

8 DSC Calorimetry Differential Scanning Calorimetry was performed on LF and HF ski-waxes.

9 Rheological Analysis HF ski waxes -1 Anton Paar Physica MCR 301 rheometer: rotational configuration, parallel plate geometry, with a 60 mm diameter. Wax viscosities as a function of temperature have been collected ranging from 120 to 150 C. Typical shear stress vs. shear rate measurements have been performed in Hz range (shear rate), with a 1 mm gap between the two plates Typical rheological curves of high fluorine ski-wax at C, exhibiting a Newtonian behavior. Viscosity is determined by the slope.

10 Rheological Analysis HF ski waxes -2 Viscosity data fit quite well the Arrhenius plot, that can be constructed according to Eqn 1 log Visco = A ISO + E act-vis /2.303 R T (1) where A ISO is the pre-exponential factor, E act-vis is the activation energy of viscosity, R is the gas constant, and T is the absolute temperature. Viscosity of various HF Yellow ( ), Red ( ) and Blue () skiwaxes, for hot, medium and cold snow, respectively. *HF Blue ski-wax exhibits a higher viscosity, and similarly a higher activation energy in the flow process. *The case of HF-4 Blue (very high values) is directly dependent on inorganic filler (a silicate), as revealed by infrared analysis on the residue after TGA.

11 Ski-Wax Degradation Thermogravimetric analysis was performed by using a thermobalance TG 5000IR (TA Instruments) with an air flow of 200 ml/min for both dynamical and isothermal method. Dynamical method was used for studying the full degradation of ski-wax in the range C at a heating rates of 10 C/min (Figure I). In the case of isothermal method, TGA experiments were carried out at selected temperature in the range C up to 15 minutes (Figure II). Figure I. Dynamic TGA test Figure II. Isothermal TGA test

12 Perfluorinated F-Ski-Wax TGA Degradation F-Blue Ski-Wax for cold snow

13 Perfluorinated F-Ski-Wax TGA Degradation F-Red Ski-Wax for medium snow

14 Perfluorinated F-Ski-Wax TGA Degradation F-Yellow Ski-Wax for hot snow

15 High Fluorine HF Ski-Wax -TGA Degradation HF-Yellow Ski-Wax for hot snow HF-Red Ski-Wax for medium snow HF-Blue Ski-Wax for cold snow

16 Low Fluorine LF Ski-Wax TGA Degradation LF-Yellow Ski-Wax for hot snow LF-Red Ski-Wax for medium snow LF-Blue Ski-Wax for cold snow

17 Isothermal TGA Degradation High Fluorine HF Ski-Wax HF-Yellow Ski-Wax for hot snow HF-Red Ski-Wax for medium snow HF-Blue Ski-Wax for cold snow

18 CONCLUSIONS The present work is a first step of a detailed study highlighting molecular features to be tuned in order to tailor the final properties of the wax. FTIR spectroscopy results very fast and sensitive for determination of low fluorine content skiwax. NMR is a powerful technique for the acquisition of detailed information on the molecular structure. DSC and rheological analysis performed on LF and HF ski-waxes, evidenced melting and crystallization phenomena, and the difference flow behavior in dependence on the composition, as complementary information for the skimen in the waxroom. TGA analysis revealed that perfluorinatedski-waxes (F) degrade almost completely in the range of C. It is definitively worth noting that all HF ski-waxes exhibit a significant mass loss of about 1-6 % in the range of temperature C, as shown in both dynamical and isothermal TGA experiments.

19 Acknowledgements This activity has been supported by the University of Trento (UniTN) with the project Skiwax The research group of Ski-Wax 2013 at the Department of Industrial Engineering (University of Trento) is composed by -Denis Lorenzi (graduated cooperator for thermal analysis), -Riccadro Ceccato (professor of Chemistry), -Emanuela Callone (graduated technician for NMR spectroscopy), -Luca Fambri (professor of Polymer Science and Technology)

20 EXPERIMENTAL INFRARED SPECTROSCOPY (FTIR) was performed with an ATR-FTIR spectrometer Spectrum One (Perkin Elmer) in the range cm -1. DIFFERENTIAL SCANNING CALORIMETRY (DSC) analyses were performed by using a Mettler DSC30 calorimeter. Melting temperature, crystallization temperature and crystallinity were studied with a heating-cooling-heating cycle at ±10 C/min in the range C flushing nitrogen at 100 sml/min. RHEOLOGICAL TESTS were performed by means an Anton Paar Physica MCR 301 rheometer, in rotational configuration, using parallel plate geometry, with a 60 mm diameter. Wax viscosities as a function of temperature have been collected ranging from 120 to 150 C. Typical shear stress vs. shear rate measurements have been performed in Hz range (shear rate), with a 1 mm gap between the two plates. The viscosity expressed is reported in cpoise (=10-3 Pa s) as function of temperature. THERMOGRAVIMETRIC ANALYSIS (TGA) was studied by using a thermobalance TG 5000IR (TA Instruments) in air atmosphere in dynamic heating at +10 C/min between 40 and 700 C; and isothermal condition at C. SOLID STATE NMR analyses were carried out with a Bruker 400WB spectrometer operating at a proton frequency of MHz. NMR spectra were acquired with proton decoupled sp pulse sequences under the following conditions: 13C frequency: MHz, pulse length 3.8 µs, decoupling length 6.3 µs, recycle delay: 200 s, 1k scans. Samples were packed in 4 mm zirconia rotors, which were spun at 5 khz under air flow. Glycine was used as external secondary reference.

21 Perfluorinated F-Ski-Wax TGA Degradation F-Blue Ski-Wax for cold snow

22 Perfluorinated F-Ski-Wax TGA Degradation F-Blue Ski-Wax for cold snow

23 Perfluorinated F-Ski-Wax TGA Degradation F-Blue Ski-Wax for cold snow

24 Mettler TG50 Fig. 8. Thermogravimetric analysis (TGA) data for poly(methyl methacrylate) (PMMA) and polyamideimide (PAI): (a) residual mass fraction versus temperature; (b) mass loss rate versus temperature.