High Performance Polymeric Materials for Sport Equipment, Functional Clothing and Footwear: Interactions of Materials, Human Body and Environment in Terms of Mechanical, Thermal and Ergonomic Properties

The study of the influence on mechanical, thermal and ergonomic properties of advanced polymeric materials used to produce outdoors gear and footwear has been the topic of the present PhD thesis. The study has addressed several aspects of ergonomics, safety and mechanical properties of sport equipment: - The evaluation of thermo-physiological comfort of soft-shell back protectors, investigating how design and materials can affect moisture management and heat loss. Heat retention has been identified using infrared thermography. Testers have answered a questionnaire to take into account their subjective sensations. - The effect of liners used in ski boots. Three different ski boot liners have been tested to evaluate the insulating behaviour and the moisture management capability of the materials used. Tests have been conducted in climatic chamber and then repeated in real skiing conditions. Scanning Electron Microscopy has been used to evaluate the effect of cells morphology on thermal insulation. - The effect of different materials used for the production of thermo-formable ski boots have been analysed in order to determine their performance in the process used to adapt the shape of ski boots to the skier’s foot morphology. The effect of foot compression on the thermal comfort has also been evaluated. - The effect of glass fibre/rubber composites on the grip on icy surfaces. The study has been conducted analysing the friction of a ski boot sole containing an insert made of composite material and comparing the results with those obtained using rubber and a thermoplastic elastomer. Scanning Electron Microscopy has been used to perform the morphological analysis of the composite. - Thermal comfort of trekking shoes has been evaluated in climatic chamber using wireless temperature and relative humidity sensors embedded in the midsole. Evaluation of heat retention through the sole and the upper has been performed using thermal imaging

Thermal behaviour of ski-boot liners: effect of materials on thermal comfort in real and simulated skiing conditions

The choice of the appropriate material for the construction of ski-boot liners is of fundamental importance in order to achieve ergonomic comfort and high thermal insulation. In this work the effect on thermal comfort of different materials used for commercial ski-boot liners has been analysed. The thermal insulation and the moisture management of liners made of different materials have been tested both in a climatic chamber and in outdoor conditions using wireless sensors combined with infrared thermography. The results obtained show substantial differences in terms of thermal comfort between the liners in the same environmental conditions, showing that closed cell ethylene vinyl acetate foams provide the best thermal comfor

Ski Boot Soles Based on a Glass Fiber/Rubber Composite with Improved Grip on Icy Surfaces

Abstract A study on the effect of glass fibers/rubber composites on the grip on ice has been conducted in order to develop new materials for ski boot soles with increased grip in winter environments. The study has been conducted analyzing the friction of a composite material and of a ski boot sole containing an insert made of the composite material and comparing the results with those obtained using rubber and a thermoplastic elastomer. The analysis of the morphology of the composite surface, by Scanning Electron Microscopy, shows a homogenous distribution of glass fibers of approximately 10 μm of diameter in the rubber matrix. Moreover, the measure of the contact angle shows that the composite material has a higher water repellency compared to the rubber matrix. The measure of the coefficient of friction indicates a significant effect of the glass fibers on the grip on icy surfaces. The increased grip can be ascribed to the stiffness of the glass fibers that are able to have a mechanical grip on the ice surface and to the increased contact angle and water repellency of the composite that decrease the formation of a water layer below the sole

Thermal behaviour of ski-boot liners: effect of materials on thermal comfort in real and simulated skiing conditions

The choice of the appropriate material for the construction of ski-boot liners is of fundamental importance in order to achieve ergonomic comfort and high thermal insulation. In this work the effect on thermal comfort of different materials used for commercial ski-boot liners has been analysed. The thermal insulation and the moisture management of liners made of different materials have been tested both in a climatic chamber and in outdoor conditions using wireless sensors combined with infrared thermography. The results obtained show substantial differences in terms of thermal comfort between the liners in the same environmental conditions, showing that closed cell ethylene vinyl acetate foams provide the best thermal comfort

Effect of the visco-elastic properties of thermoplastic polymers on the flexural and rebound behaviours of ski boots for alpine skiing

The flexural behaviour and elastic rebound are the main parameters that determine the global performance of a ski boot during skiing. These two parameters are related to the visco-elastic properties of the polymeric materials used. For this reason, the visco-elastic properties of the materials most utilized for the production of ski boots (polyurethanes and polyolefins) have been studied using dynamic mechanical thermal analysis in a temperature range between '30 \ub0C and +50 \ub0C. Also, the flexural and rebound behaviours of the boot have also been tested using specially designed test benches. The dynamic mechanical thermal analysis results and the flexural and rebound tests results were compared, and a significant effect of the visco-elastic properties on the flexural and rebound behaviour of ski boots was seen. Therefore, dynamic mechanical thermal analysis can be used in a knowledge-based design process of new ski boots in order to improve on-snow performances

Ski boots for Alpine Skiing: Designs, Materials and Testing Procedures

The book reports the recent advances in the study, in the design, in the testing procedures and in the production of ski-boots for alpine skiing. An overview of the different designs and of the materials used in ski-boot construction is provided along with a detailed study of the literature on this subject. Particular emphasis is given to the combination of design and materials properties on the final performances and on the boot design

Thermal comfort of soft-shell back protectors for alpine skiing

Introduction In the last few years the soft-shell back protectors have widely replaced the previously used hard-shell protectors. The soft foamed materials used for soft-shell back protectors provide great impact absorption capability due to their pseudo-dilatant behaviour that permits to the protector to be soft under low speed impacts and to become hard for high speed impacts. Moreover, the soft foams provide a better fit over the body and allow manufactures to create perforated structures of the foam pad that can improve the temperature control and moisture management. The aim of this work has been to measure how back-protectors perform, in terms of heating, cooling, moisture management and therefore overall thermal comfort, under controlled environmental conditions. Three different commercial back protectors have been used in order to compare how materials and design can influence the above mentioned thermal properties. Materials/Methods Five testers have tested three types of soft shell back protectors in a climatic chamber in order to evaluate the thermal performances of each back protector. Temperature and humidity sensors, distributed in 11 different body positions, have allowed the measure of the skin mean and torso temperatures and the microclimate humidity and temperature in the zone between the skin and the back-protector. Moreover, the mechanism of heat dissipation has bee studied usingthermo-graphic imaging. The tests have been performed running on a treadmill under controlled physical activity. Both objective and subjective parameters have been analysed, in order to define an appropriate method for the comparison of back protectors with different materials and designs. The physical activity level has been evaluated using an heart rate monitor, while the sweat rate has been used as indication of the thermal stress of the tester. Results and Conclusions. The method developed in this work has allowed a detailed evaluation on how the different types of back protectors influence the thermo-physiological comfort of the final user. The results obtained show minor differences from a global point of view (Average Skin Temperature). However, looking more in detail into the thermal micro-climate locally in the torso area (Average Torso Temperature), the differences are larger still maintaining the same thermal performance hierarchy of the average skin temperature

effect of ski-boot design on flexural and rebound performances

this chapter reports the study of the effect of different designs on the flexural and rebound behavior of ski-boots. The effect of the materials used for the different parts is also analyzed in detail

Thermo-physiological comfort of soft-shell back protectors under controlled environmental conditions

The aim of the study was to investigate thermo-physiological comfort of three back protectors identifying design features affecting heat loss and moisture management. Five volunteers tested the back protectors in a climatic chamber during an intermittent physical activity. Heart rate, average skin temperature, sweat production, microclimate temperature and humidity have been monitored during the test. The sources of heat losses have been identified using infrared thermography and the participants answered a questionnaire to express their subjective sensations associated with their thermo-physiological condition. The results have shown that locally torso skin temperature and microclimate depended on the type of back protector, whose design allowed different extent of perspiration and thermal insulation. Coupling physiological measurements with the questionnaire, it was found that overall comfort was dependent more on skin wetness than skin temperature: the participants preferred the back protector with the highest level of ventilation through the shell and the lowest level of microclimate humidity

Thermo-mechanical and impact properties of polymeric foams used for snow sports protective equipment

The thermo-mechanical and impact properties of materials used for hard-shell and soft-shell back protectors have been analysed in order to understand the mechanism of action of the foams used for protective equipment. Dynamical mechanical analysis has shown that materials used for soft-shell protectors present frequency-sensitive properties that permit to have a soft response when stressed at low speed and a hard response when subjected to a high-speed impact. Furthermore, by means of drop weight impact tests, the shock absorbing characteristics of the materials have been investigated at two temperatures pointing out the differences between soft and hard-shell protectors; in addition it has been demonstrated that the materials used for soft-shell protectors maintain their protective properties after multi-impacts on the same point