MATERIALS New Polymers in the Footwear Industry
MATERIALS
New Polymers in the Footwear Industry
Ana Marija Grancaric, Anita Tarbuk
With the support of the Lifelong Learning Programme of the European Union 1 MATERIALS New Polymers in the Footwear Industry
Footwear materials
History of footwear materials
• First material evidence of the existence of shoes dates back to the Paleolithic (pre-historic era). But it is generally assumed that the usage of shoes began much earlier.
• From hemp and leather to plastics:
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Footwear materials
Wool Nylon Polypropylene Natural materials Cotton Synthetic materials Jute Polystyrene Wood Polyethylene Horn Polyvinylchloride Ivory Bakelite Leather Epoxy resins Natural caoutchouc Organic glass Polyurethane Synthetic rubber Color and varnishes: Shellac Biopolymers Resin Linseed oil EVA (…)
Adhesives: wax (paraffin, beeswax, carnauba)
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Footwear materials
Footwear materials… Today!
• Due to its properties, Leather is considered indispensable in the footwear industry.
• Skin leather is the type of leather most commonly used thanks to its low price and good visual appearance.
• It should be noted that the artificial leather industry is so technically advanced that it is often difficult to assess whether the shoe is made of real or artificial leather.
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Footwear materials
• Another important material used in footwear industry are the Textiles.
• Both natural and man-made fibers can be found in almost every shoe, used either as reinforcement, pads or linings.
Other commonly used materials are:
• Metal (used for additional reinforcement or as accessory) • Rubber and Plastics (used mainly in soles and heels, and sometimes can be found in the shoe itself) • Glue (used for joining the different parts)
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Footwear materials
Natural fibers
Vegetable fiber Animal fiber Mineral fiber
Seed From Keratin Fiber from Asbestos husks Cotton Wool other Coconut animals Kapok Hair Silk Akon Mohair Wild silk: Cashmere Tussah Angora wool Anafi Stalk From Camel coat Flax leaves Llama hair Hemp Sisal Jute Manila Ramie Raffia Kenaf
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New application of vegetable fibres – cotton, flax, jute, ramie
Cotton fibers’ usage in the footwear industry: such us fabrics for lining or for the upper part of a pair of shoes.
Flax fibers’
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New application of vegetable fibres – cotton, flax, jute, hemp, ramie
The sole is of jute or ramie, upper part is made of cotton, flax or ramie, as well as sews.
Hemp
This is an interesting design by made vegetable fibers - bamboo 8 MATERIALS New Polymers in the Footwear Industry
Footwear materials
Man-made fibers
From From From natural inorganic synthetic polymers material polymers
Cellulose Protein Carbonic CF Organic Viscose Regenerated Protein PROT Glass GF Polyester Copper Metal MF Polyamide Modal Ceramic Aramid Liocelna … Polyacrylonitrile Acetic Modacrylic Triacetate Alginate ALG Polypropylene Polyester Chloric Fluorine Vinyl Natural rubber Elastane fibres
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New application of synthetic fibres
Fibers from inorganic material Carbon fiber (CF) - It has high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion, what make them very popular in aerospace, civil engineering, military, and sports. Even highly expencive, they are usually combined with other materials to form a composite.
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Footwear materials
• In the Footwear industry, plastics Most commonly used plastics are: are used for making shoe soles, • Polyvinyl chloride (PVC) heels, miser, belt ornaments, • Polyvinyl acetate (PVAC) and as replacement of natural leather • Polyethylene (PE) • Polypropylene (PP) • Polystyrene (PS) • Polyamide (PA) • Polycarbonate (PC) • Ethylene-vinyl acetate (EVA) • Polyurethane (PUR)
Bio-plastics: • Polylactic Acid (PLA) 11
MATERIALS New Polymers in the Footwear Industry
Footwear materials
PVC Polyvinyl chloride is obtained by polymerization of the vinyl chloride
. In shoemaking industry is used soft PVC (with 20 - 50% softener), mainly for producing soles, heels and all injected shoe
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Footwear materials
PVAC Polyvinyl acetate is obtained by polymerization of vinyl acetate
• Single PVAC is unsuitable for forming, so it is mostly used as a copolymer with PVC
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Footwear materials
PE Polyethylene is obtained by polymerization of the ethylene (ethene) under various conditions (pressure, temperature, catalyst)
• In shoemaking industry it is used for producing fillings, heels and insoles
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Footwear materials
PP Polypropylene is obtained by polymerization of the propylene
• In shoemaking industry it is used for producing all height of heels, shoe molds and filling
Propylen Polypropylen
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Footwear materials
PS Polystyrene is obtained by polymerization of styrene
• In shoemaking industry it is used for producing shoe soles and low heels
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Footwear materials
PA Polyamide is usually obtained by condensation and polymerization of diamine and dicarboxylic acid
• In shoemaking industry it is used for producing shoe soles, sports shoes, high heels and thin heelpiece
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Footwear materials
PC Polycarbonate is saturated polyesters of carbonic acid of the general formula
• In shoemaking industry it is used for producing soles and heels
(-ORCO-) n
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Footwear materials
Nitributadien Rubber (NBR)
It is resistant to oil, fuel and other chemicals. It contains more nitrile within the polymer, so it has higher resistance to oils but lower flexibility as a material. NBR is used in the preparation of specialized shoes, like coating from oil and chemicals.
The shoe above has a pre-molded Rubber Nitrile Sole.
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Footwear materials
Thermoplastic Rubber (TR)
Thermoplastic rubber (TR or TPR), one of the most common materials for making footwear outsoles, has been in use in the footwear industry since the 1960s. Although it is not suited to every type of footwear, outsole material TR is widely used in a variety of different types from everyday fashion/casual shoes to slippers (as it is flexible) and sneakers (as it is slip resistant). In the latter, application it is often seen in the form of a thin outsole bonded to a lightweight EVA midsole for cushioning.
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Footwear materials
PUR Polyurethanes • Has properties similar to rubber • Excellent material for getting plastics and synthetic fibers • Can be both, thermoplastic and thermoset
Thermoplastic PUR Thermoset PUR
• Constructed of linear • Can be formed up to 8 times. macromolecules that are related • The molecules are linked by with physical connections. chemical bonds. • At high temperature physical • Grid-like structure occurs at a connections are torn and temperature higher than 100oC. polyurethane can be shaped by • Can not be reformatted. casting.
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Footwear materials
Pressing • The plastic is melted in the injection molding machine and then injected into the mold, where it cools and solidifies.
Molded Part Molten Plastic Raw Plastic
Injection Molding Machine
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Footwear materials
Processing of Plastics is simple and short…
…and the product Advantages Disadvantages immediately gets of using Plastic of using Plastic its final shape and appearance. • Resistant to: air, water, • Not resistant to high- bacteria temperature • Little density, low • Low permeability electrical and thermal to air and water vapor conductivity, watertight • Not degradable • Strength and toughness pollutant • Smooth and flat surfaces (doesn't require further processing) • Easy to maintain
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MATERIALS New Polymers in the Footwear Industry
New polymers
EVA Ethylenvinylacetat is obtained by polymerization of ethylene and vinyl acetate
• Can be used alone or in combination with other polymers. (Commonly) is produced as expanded material in plates sole cropping (soles for lightweight summer shoes, middle soles)
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New polymers
Energy BOOST™ Designed with an energy-returning boost™ midsole, these running shoes feature a techfit™ upper and the TORSION® SYSTEM for support. Energy-returning boost™ midsole keeps every step charged with an endless supply of light, fast energy; TORSION® SYSTEM for midfoot integrity techfit™ technology for lightweight and flexible upper support Flexible textile upper with welded synthetic overlays for support and stability External heel counter for maximal heel fit and running comfort; miCoach® compatible ADIWEAR™ outsole offers the ultimate in high-wear durability
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MATERIALS New Polymers in the Footwear Industry
New polymers Energy BOOST™ Boost is a combination of EVA foam and TPU (Thermoplastic Polyurethane).
Thousands of unique energy storing capsules are blown together to provide an energy return and performance comfort to the runner. We're confident runners have never before felt this level of comfort. Boost is soft, bouncy and provides the ultimate in performance; it's lightweight, durable, comfortable and springy.
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New polymers
Energy BOOST™
How does the technology work?
It's a proprietary, non-EVA foam that is made up of individual energy storing capsules that are then blown together in a unique molding process. During the development process, each capsule forms a skin on the outside which, when blown together forms the technology called Boost. There are more than 2,000 individual capsules in a size 9 Energy Boost shoe.
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New polymers
Energy BOOST™
What's the difference between regular EVA foam and Energy Boost?
Since 1981, compression molded EVA has become the standard running shoe midsole. Even it is great because of the nature of EVA expansion, it starts breaking down after the first few months. In other words, the shoe you buy today will have significantly different performance after 100, 200, 300 miles of use.
In the heat, in the cold, and after countless miles, Boost cushioning performs more consistently and doesn’t lose its cushioning properties like standard EVA.
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New Polymers
Bioplastics
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New Polymers
Why bioplastics?
• Safer & more friendly for our planet • Polymers made from renewable, biobased resources and has a considerably lower carbon footprint than other plastics. • Biodegradable, leaving behind no harmful substances. • Positive business impact • Consumers are becoming increasingly aware of their impact on our planet and are starting to appreciate and seek out more environmentally friendly alternatives. • Bioplastics also alleviate our reliance on increasingly expensive oil-based sources.
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New Polymers
BioPlastics
• Can be made from natural or synthetic polymers • Natural: cellulose, stark • Synthetic: BIO-PE, PLA-polylactic acid, PGA-polyglycol, PHB-polyhydroxybutyrate, PHA-polyhydroxyalcanoate
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MATERIALS New Polymers in the Footwear Industry
New Polymers
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New Polymers
Thermoplastic stark
glycerol Thermoplastic stark
Amilose Amilopectine
Stark (patatoe, corn) Usage: • Packing • Fiber mixture • Composites
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MATERIALS New Polymers in the Footwear Industry
New Polymers
Polylactid acid (PLA)
• Made from sugar cane, sugar beet or corn
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MATERIALS New Polymers in the Footwear Industry
New Polymers
PLA bioplastic applications Sportswear • Molded plastic parts • Fibre • Foam • Film High heat resistance Good breathability Safety helmet Soft and tactile feel High heat resistance Washable and durable Durable Weavable Fresh fruit packaging Transparent and compostable Boots 100% biobased and recyclable Low temperature impact High strength Automotive industry High heat resistance Consumer electronics Durable High heat resistance Hydrolytic stability Excellent surfaceappearance Foamed inner shell Durable High impact
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Recycling
Recycling leather
• How to recycle tanned leather is still an open question (not as evident as plastics which is simply melt and transformed into new products). • Few solutions are offered: • Repair the existing damaged product • Find a new usage for existing product • Transform leather waste into panels for various uses and products, e.g. design
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Recycling
• Repair the existing damaged products
• various preparations and methods can give leather an old glow
Suggested video: Repair Gucci Leather Sole/Busy Bee Newmarket http://www.youtube.com/watch?v=G9He6TkGOco
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Recycling
• Find a new usage for existing products
• creative minds can give a whole new meaning to the old leather item or to an useless leather waste
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Recycling
• Design from leather waste panels
• Is composed of leather waste from different usages - furniture, footwear, accesories and other factories. This leather is then ground into shreds, combined with water and then mixed with binding products, such as natural rubber and acacia wood bark. The leather is then shaped into a panel, sheet or a roll to be mechanically processed according to the customer’s requirements (specific size, color, and texture).
• Panel design can have different uses, such as reinforcements in shoemaking, floors in construction industry, among others.
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Thank you for your attention
ΠΟΛΥΤΕΧΝΕΙΟ ΚΡΗΤΗΣ Centro de Formação Virtual Campus, Lda. Technical University of Crete Profissional da (Portugal) (Greece) Indústria do Calçado (Portugal)
Sveučilište u Zagrebu, Instituto de Biomecánica Universitatea Tehnica Tekstilno-tehnološki de València Gheorghe Asachi Iasi fakul (Spain) (Romania) (Croatia)
This project has been funded with support from the European Commission. This publication reflects the views only of the author, and the Commission cannot be held responsible for any use which may be made of the information contained therein.
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