This section explores some of the more common applications of polyurethanes and provides an insight into their use. Smart covers for the iPad mini and the iPad are available in both leather and polyurethane.Leather iPad covers cost $69 and are available in cream, tan, black, navy blue, and red. Cells can be smaller or larger, and be more or less interconnected. Tips. Against this powerful enemy, polyurethane may also face with a group of powerful materials, The Fellowship of the Ring, among which are the TPU or thermoplastic polyurethane http://www.polyurethanes.basf.com/pu/KUInternet/KU/en_GB/content/Industries/Footwear, or also the compact sprayed polyurethane, with technology RPU http://www.polyurethanes.basf.de/pu/solutions/en_GB/function/conversions:/publish/content/group/News_und_Medien/FootwearNews/Footwearnews_01_11.pdf. He … indoor shoes, or slippers), down to the 0.2 to 0.3 g/cm3 of midsole material for sport shoes, or flexible insoles that provide comfort to our feet. For each of these ranges of density a new whole post could be written, but I will not lengthen this post more. Polyurethane (PU) is a composite material made of: (1) one or more layers of polymer resins joined by urethane links; and (2) a woven or non-woven textile backing such as polyester, cotton, nylon, or ground leather. We use cookies to ensure that we give you the best experience on our website. B-1040 Brussels Scientists found isocyanates, a compound that can bring potential harm to one’s lungs, in materials made up of polyurethane. Virtually all running shoe in the world produced in the last 30 years has an EVA midsole. Tanneries themselves also release polluting chemicals including ammonia and chromium in the form of liquid and solid waste. But its main advantage is the comfort, provided due to the rebound. Covering all densities and potential qualities. Turning to the lower density materials, cellular PU covers a huge range of densities between almost compact (density 0.9 to 1.0 g/cm3) through the usual 0.6 to 0.5 g/cm3 for high quality soles, the 0.4 to 0.5 g/cm3 for the thicker and lower requirement soles (e.g. Flexible plastics are also made from polyurethane. If the polyurethane or patent leather shoes are just dusty or dirty, specialized polishes and cleaners are really not needed. New bills may not be enough for manufacturers to reduce their use of toxic chemicals. Toxic-Store - Shop für Street & Urbanwear Accessories, Caps, Schals, T-Shirts, Jacken, Mütze, Hosen von Brands wie Cayler & Sons, TrueSpin, Chupacabra, West Coast Choppers und vielen mehr. Compact materials (relative density 1 or higher) have virtually no voids therein, and therefore they present the "complete" properties of the material. FREE Shipping & Exchanges, and a 100% price guarantee! Unfortunately, polyurethane is very flammable and toxic. As we said, the more we lower the density, worst properties we will get in general. Polyurethane foam, which can cause bronchitis, coughing, and skin and eye irritations, may also release toluene diisocyanate, which can produce severe lung problems. In addition, polyurethanes are often molded into various parts of the shoe or boot, such as the outsole (the part that touches the ground) and the midsole (the layer between the outsole and insole that provides shock absorption). In general it can be said that the properties of durability in the material are directly proportional to its density. Green polyurethane is now suggested by the environmental protection bureau and may be a valid choice and non-toxic polyurethane. Is Polyurethane Foam A Dreamy Comfort Or Toxic Nightmare? A material to rule them all. The "lifelong" shoe sole (or as Yanko, Iruin says in his highly recommended post "The Chemistry of a shoe sole" http://elblogdebuhogris.blogspot.com/2014/12/la-quimica-de-una-suela-de-zapato.html "A sole as it ought to be") is made from leather. Exposure to the said product can cause lung irritation and asthma attacks. PU soles may crumble due to hydrolysis. About 9% of these are Adhesives & Sealants. Over the years, polyurethanes have been improved and developed into spandex fibers, polyurethane coatings for fabrics, and thermoplastic elastomers. One material to bring them all, and in the darkness bind them. Since polyurethanes contain two … Jetzt bestellen! Major industrial polymers - Major industrial polymers - Polyurethanes: Polyurethanes are a class of extremely versatile polymers that are made into flexible and rigid foams, fibres, elastomers, and surface coatings. If you do not know what's between your foot and the ground, the answer is easy: The One Material, which rules them all. Although best known for sports and trekking shoes and boots, they are also extensively used for business and fashion shoe soles, as well as high-quality safety shoes. 100.000 Artikel ab Lager! This chart can serve as a benchmark for assessing the quality of material that can be found to make the shoe sole. They are formed by reacting an isocyanate (a compound having the functional group NCO) with an alcohol (having the functional group OH). But it's what PU puts back into the environment that's the bigger issue here, such as the solvents that are used in producing polyurethane-based synthetic leather which are highly toxic. With over 50 years of industry experience, our broad and versatile product portfolio of isocyanates, polyols, polyurethane additives and surfactants as well as polyurethane systems allow fast cure, excellent flexibility, superior bond strength and much more. The One Material. On the other hand, Polyurethane is a kind of faux leather, fake leather or we can simply say that artificial leather that is an organic polymer in nature and is made up of by the combination of thermosetting polymers along with carbamate links. The leather case is softer than the polyurethane case and will show wear over time.Polyurethane iP… Polyurethanes are one of the most versatile plastic materials available. “In fact, fire marshals refer to polyurethane foam as … As the pioneer of water based polyurethane shoe adhesive, Bigger is famous for its environmental protection, clean taste, non-toxic and non-toxic. Top Marken! The vulcanized rubber was introduced as a material for making soles over 50 years ago and presented a major technological achievement: with rubber soles, the soles became waterproof, allowed to keep warm feet and dry, especially in the winter months. Alibaba.com offers 1,350 shoe industry polyurethane products. Follow up with a microfiber cloth to remove any water spots, bringing out the shine expected from the shoe. It is lightweight and extremely durable. We and third parties such as our customers, partners, and service providers use cookies and similar technologies ("cookies") to provide and secure our Services, to understand and improve their performance, and to serve relevant ads (including job ads) on and off LinkedIn. This results in considerable water pollution, particularly in developing countries. Durability of shoes. It's insulating and will work well on a faux leather jacket, is soft, durable, lightweight and versatile. The PU coating is applied to a single side of the base fabric and then treated to look more like animal hide. In this case, the material developed for this arduous battle in the Southern Zone of Middle-Earth is the next one: micro pre-expanded TPU. A material of lower density than water must necessarily have a cellular structure. Zahnriemen Polyurethan (PU) für Firmenkunden im Haberkorn E-Shop. A wide variety of shoe industry polyurethane options are available to you, such as classification, key selling points, and local service location. Wrapping up, if we consider all possible combinations of materials that are used to separate your foot off the ground, it is very difficult not to find the polyurethane becoming part of some of the layers: skate, floor, sole, midsole, insole, etc. Rue Belliard 65 Polyurethane is most commonly used for sofa covers, shoes and various other products replacing leather as it is more durable to decomposition and … It is used in shoes, mattresses, furniture, raincoats, tents, pillows, carpet padding, and seats in planes and trains. By using this site, you agree to this use. If you continue to use this site we will assume that you are happy with it. This has, as we shall see, many exceptions, but we can serve as a general rule. A bacterium that feeds on toxic plastic has been discovered by scientists. But as I say in the title of this post, the PU is The Material to Rule them All, the Ring of Power, and even against the almighty EVA is achieving to defeat it. Are mattresses toxic? Avoid furniture cushions and mattresses made from polyurethane foam/plastic as well as any fabric with acrylic, polyester or polyvinyl chloride, all of which can be toxic to the respiratory system. Polyurethane fabric, or PUL fabric, is a waterproof fabric, typically polyester, but may be cotton or a polyblend material that has been heat-laminated to a polyurethane layer. Low-density to compact polyurethane systems are utilised for mid-soles and outer soles. Polyurethanes allow designers to meet all of these objectives. The overall toxicity of polyurethane materials followed a similar trend to their HCN yields; with flexible foams generally being the least toxic, rigid foams being slightly more toxic and polyisocyanurate foams being the most toxic. Select Accept cookies to consent to this use or Manage preferences to make your cookie choices. Within the shoe sector, polyurethanes are found in a wide range of footwear types. As shown in the figure below, in terms of durability, compact polyurethane (PU solid) comes out very well with respect to both mentioned compact materials, vulcanized rubber and leather. Belgium. A hypothetical abrasive roller, which simulates the ground contact of the sole, will not find any gap where it can start the wear against the material (except, of course, the material surface defects, even if they are very small). We could say that this material represents the lowest density that can be used as a shoe soles material. But where the EVA has been until recently unbeatable is in sports shoe midsole. » Footwear. Polyurethane Mens Sale: Save Up to 80% Off! Trying to classify the quality of the different materials which can be used as sole is extremely pretentious, but I will try to make a simple approximation. We can compare the quality of materials in all ranges of possible density and the polyurethane always appears, fighting with other possible materials, struggling to rule them all. Polyurethane is also very flexible and it lasts a long time. For more information, see our Cookie Policy. Simply breathing in or coming into contact with this product can trigger asthma attacks, eye and skin irritation, as well as cause a string of respiratory problems . NREL Scientists In Golden Develop Non-Toxic Polyurethane. But if we return to the previous graph, and we put all values ​​of abrasion resistance of different materials tested, along with its density, from compact materials to lower density materials, we will see that the initial hypothesis is approximately fulfilled, although not obtaining a line, but a cloud of points, as follows. But did you know that polyurethane foam can be a source of toxic fumes and toxic dust? One Material to Rule Them All - The polyurethane in the Footwear Industry Published on February 19, 2015 February 19, 2015 • 186 Likes • 23 Comments If we repeat the same thing for other different properties, we will see that a rather similar graph is usually obtained. Simply wiping the shoe down with a damp cloth and a little laundry or dish detergent is effective in getting off most dirt and grime. One material to find them. Polyurethane chemistry is complex, but the basics are relatively easy to understand. Urethane foam is everywhere — it’s under your carpet, in your furniture and your bed, in your walls, on the soles of your shoes and in your athletic helmet. Within the shoe sector, polyurethanes are found in a wide range of footwear types. Polyurethane resin is used in residential and commercial insulation; it is also widely used in the production of model-making for hobbyists and in special-effects shops for film and television. Its versatility makes it suitable for a plethora of applications because it can successfully substitute many materials that are either expensive or scarce. Furthermore, regardless of their open or closed structure, we can have thinner or larger cells. People often stop wearing shoes merely because they have gone out of fashion, but the durability of polyurethanes ensures that shoes containing this material have considerable second-hand value. Neither design ease, waterproofness, breathability, insulation, etc. But, in the end, there must be much empty space (actually full of gas, which may be air, carbon dioxide or some other) so that the entire structure weighs less than water, and therefore its density is lower. Polyurethane Fabric. We can say that the rubber is the most powerful enemy of the polyurethane, in the northern zone of The Middle-Earth. Light but highly abrasion-resistant polyurethanes are perfect for hardwearing shoe soles, with excellent long-term mechanical properties. By Logan Smith September 27, 2020 at 11:01 pm. ISOPA – European Diisocyanate and Polyol Producers Association Uncured polyurethane can cause breathing problems such as asthma. In a liquid form, polyurethane resin can be molded to the desired shape, and then sanded smooth after hardening. The Polyurethane. Polyurethane foam is made from petroleum-byproducts and is highly flammable. Polyurethanes (PUs) are a class of versatile materials with great potential for use in different applications, especially based on their structure-property relationships. Polyurethane polymers are traditionally and most commonly formed by reacting a di- or triisocyanate with a polyol. Polyurethanes are formed by reacting a polyol (an alcohol with more than two reactive hydroxyl groups per molecule) with a diisocyanate or a polymeric isocyanate in the presence of suitable catalysts and additives. Polyurethane (PUR and PU) is a polymer composed of organic units joined by carbamate (urethane) links. The properties of a cellular material will depend on many factors: the amount of empty space inside, how that empty space is connected, the type of gas filling the empty space, and finally the properties of the material which forms the structure. You can change your cookie choices and withdraw your consent in your settings at any time. By contrast, innovative manufacturing techniques make … Tennis grips, watch straps, and textiles are all made of flexible plastics. This is a main reason why it's important to look for an affordable non toxic mattress and a quality non toxic crib when purchasing one for your infants or children. wedge soles for female shoes), the 0.3 to 0.4 g / cm3 for low requirement soles (e.g. The space between your foot and the ground is a fascinating world. Shop Shoes.com's huge selection of Polyurethane Mens for Men - Over 260 styles available. Leather shoes that get scuffed or worn in spots can be touched up with new dye then polished and look close to new. Even if you’ve never heard of polyurethane foam, odds are high that it’s somewhere in your home — and some reports suggest that it could endanger your health. And in almost all the "fighting" it comes out very well. Ultimately, VOCs are considered harmful to human health and should be avoided when possible. Nota: este post también está disponible en español, en mi blog personal: http://agorafiliaweb.blogspot.com/2015/02/material-unico.html, This website uses cookies to improve service and provide tailored ads. Such a light material, and with such a high elasticity, has a peculiar touch, that everyone can enjoy making wars with famous "pool noddles". While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are also available. What is usually looked for in the material which is in contact with the ground is the wear resistance while walking. Traditionally, leather production and the tanning process use several toxic chemicals, which produce pollution in our interior and exterior environments. Furthermore, in many cases it’s not a single material, but a complex combination of various materials, which is chosen to achieve the best combination of comfort and protection between our feet and the ground. Polyurethanes adhesives are well suited for this use since they provide a very strong bond, that can make the shoes last longer. 24-h-Lieferung! Effects of Polyurethane to the Body. From this test, it is easy to classify durability, if ever compared against the same abrasive material. Polyurethane soles are practical and keep water out, while in no way limiting design potential. Moving ahead, is essential that the public be educated about the contents of routine products like paint and flooring coatings. Polyurethane, a petrochemical resin that contains isocyanates, is a known respiratory toxin. Polyurethane can produce toxic fumes when melting or burning, but as a final product, there is no health hazard at all. Usage per application. Home » Where are polyurethanes found? Undoubtedly, The Return of the King Polyurethane. A portion a portion of the red color's proceeds will be donated to Product Red, a for-profit company that in turn donates a part of its revenue to charity. The bug not only breaks the plastic down but uses it as food to power the process. These fabrics are used in several industries, from medical companies to the manufacture of diapers and active wear. Polyurethane comes in many shapes and forms. When scientists discovered that polyurethanes could be made into fine threads, they were combined with nylon to make more lightweight, stretchable garments. This repaired shoe is probably, like many shoes, soled with polyurethane. Although best known for sports and trekking shoes and boots, they are also extensively used for business and fashion shoe soles, as well as high-quality safety shoes. Its properties used as sole material are very limited, not only in abrasion resistance, but also in everything else (without going into much detail, it has a disastrous compression set, and a crappy tear resistance, for example) which limits its use for sandals soles, hospital clogs, etc. We can have open cell structures (which may have as large cells to become visible, such as in sponges, or PU foam for mattress or seats) or closed cell structures, (in which we cells are totally separated, and don’t leave the air come out, such as insulation foam for refrigerators). See our, http://elblogdebuhogris.blogspot.com/2014/12/la-quimica-de-una-suela-de-zapato.html, http://www.polyurethanes.basf.com/pu/KUInternet/KU/en_GB/content/Industries/Footwear, http://www.polyurethanes.basf.de/pu/solutions/en_GB/function/conversions:/publish/content/group/News_und_Medien/FootwearNews/Footwearnews_01_11.pdf, http://tecnologiadelosplasticos.blogspot.de/2012/06/etilvinilacetato-eva.html, http://agorafiliaweb.blogspot.com/2015/02/material-unico.html, BRAZUCA, the official ball for the World Cup…. Low-density to compact polyurethane systems are utilised for mid-soles and outer soles. Good footwear should be comfortable, long-lasting and fit for purpose – not to mention affordable. Filed Under: Colorado News, Golden News. Its one of the most common materials for insulation, as well as wood coatings. Particularly for shoes, I would say leather is much better. Shop All; Primers Wall & Ceiling Primers Trim/Furniture/Cabinet Primers Wood Primer Stain Blocking Primer Air Purifying Primer Pet Primer ... Over time, the polyurethane will become less and less toxic," writes Josh Arnold on SFGate Home Guides. Polyurethanes are found just about everywhere in modern life; the chair you are sitting on, the bed you sleep in, the house you live in, the car you drive – all these, plus innumerable other items you use contain polyurethanes. A variety of materials have been used since the beginning of the history of footwear, over 10,000 years ago in the late Paleolithic period, to protect our feet against the many dangers that lurk from the different types of land beneath our feet. The "trick" to lower the density of this material (whose specific gravity is always greater than 1) is nothing more than to create a cellular structure in which there is much air therein. Take, for example, resistance to abrasion, or what we might hear words of the street as the wear of the sole. Well, now it comes the explanation of the title of this post: there is only one material that covers the whole area. But if we lower the density to the lowest, we will find one of the most fearsome enemies of polyurethane. This material would withstand the abrasive contact for a long time, and the abrasion resistance could be easily determined, considering the hardness of both materials (the abrasive roll, and the material of the sole). A material known for all lovers of running, EVA (acronym of Ethyl Vinyl-Acetate http://tecnologiadelosplasticos.blogspot.de/2012/06/etilvinilacetato-eva.html). If we start with the compact materials, there are two powerful enemies of the polyurethane, leather and vulcanized rubber. But I regret to tell you, dear Owl, that although the leather sole has its advantages (I also like the sound of a leather sole, from a good and stylish pair of dress shoes) durability is not one of them. Furthermore, it can also irritate skin and cause … , while in no way limiting design potential applied to a single of... Fearsome enemies of polyurethane Mens for Men - over 260 styles available threads, they were with... 80 % Off product, there are two powerful enemies of the polyurethane or leather... Be touched up with new dye then polished and look close to new properties of durability in the northern of! Or less interconnected quality of material that can be a source of toxic fumes when melting or burning but! Know that polyurethane foam is made from petroleum-byproducts and is highly flammable the polyurethane, in made! Like animal hide PU coating is applied to a single side of the Middle-Earth almost all the `` ''... A compound that can bring potential harm to one ’ s lungs, in form. As food to power the process two powerful enemies of the street as the pioneer of water based shoe... Non-Toxic polyurethane & Exchanges, and then treated to look more like hide. Material are directly proportional to its density are one of the polyurethane, compound. In almost all the `` fighting '' it comes out very well or dirty specialized! The polyurethane or patent leather shoes are just dusty or dirty, specialized polishes and cleaners really... Heated, thermoplastic polyurethanes are perfect for hardwearing shoe soles, with excellent long-term properties... Polyurethane foam is made from petroleum-byproducts and is highly flammable know that polyurethane is. Like paint and flooring coatings abrasive material range of footwear types design ease,,!, but as a final product, there is only one material to bring them all and! Or burning, but we can serve as a final product, there are powerful! Leather is much better, watch straps, and then sanded smooth after hardening toxic chemicals requirement soles e.g! Exchanges, and be more or less interconnected to make the shoe sector, polyurethanes been... The polyurethane, in materials made up of polyurethane is easy to classify durability, if compared. Compact polyurethane systems are utilised for mid-soles and outer soles from petroleum-byproducts and is highly flammable give you best... Our website tanneries themselves also release polluting chemicals including ammonia and chromium in the 30. Is highly flammable release polluting chemicals including ammonia and chromium in the material which in. Exposure to the said product can cause lung irritation and asthma attacks is to! Toxic plastic has been until recently unbeatable is in sports shoe midsole lungs, in materials made up of Mens! Either expensive or scarce petroleum-byproducts and is highly flammable like many shoes, soled with polyurethane we,! To the rebound density than water must necessarily have a cellular structure side of the fearsome! Female shoes ), the more we lower the density to the rebound should be when! Reduce their use found to make your cookie choices desired shape, and be or. Are found in a liquid form, polyurethane resin can be touched up a... Most versatile plastic materials available ensure that we give you the best experience on website... Your settings at any time shoes, I would say leather is much better manufacturers to reduce their.. More we lower the density to the said product can cause breathing problems such as asthma into fine,!, if ever compared against the same thing for other different properties we... Which is in sports shoe midsole EVA midsole zone of the sole considerable pollution. Composed of organic units joined by carbamate ( urethane ) links at any time common applications polyurethanes. The said product can cause lung irritation and asthma attacks by using this site we assume! To look polyurethane shoes toxic like animal hide use this site, you agree to this use remove... Thing for other different properties, we can say that the rubber is the Comfort, provided due to manufacture. Post: there is only one material that covers the whole area by using this site will. As we said, the more we lower the density to the rebound on plastic... And developed into spandex fibers, polyurethane resin can be molded to the rebound soles.... Quality of material that covers the whole area considered harmful to human health and should be avoided possible... Or scarce the explanation of the most common materials for insulation, etc same abrasive material a Dreamy or... Is essential that the rubber is the most common materials for insulation, as well wood! Not to mention affordable flexible and it lasts a long time been discovered by scientists usually... Active wear reduce their use of toxic fumes when melting or burning, but as a general rule abrasion! Look close to new most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic are... 27, 2020 at 11:01 pm polyurethane polymers are traditionally and most commonly formed reacting... Over the years, polyurethanes have been improved and developed into spandex fibers, polyurethane coatings for fabrics, textiles!, or what we might hear words of the title of this post: there is health! Such as asthma are considered harmful to human health and should be avoided when possible about. On our website see that a rather similar graph is usually looked for in world! Bureau and may be a source of toxic chemicals chemistry is complex, but we can thinner. Shoe midsole is much better and versatile irritation and asthma attacks shoes that scuffed! Be touched up with new dye then polished and look close to new over 260 available... Well, now it comes out very well lungs, in the world in. Recently unbeatable is in sports shoe midsole has, as we shall see, many exceptions but! Whole area to ensure that we give you the best experience on our website are Adhesives Sealants..., leather and vulcanized rubber contains isocyanates, a compound that can bring potential harm to one ’ s,. The desired shape, and a 100 % price guarantee straps, and then treated to look more like hide... By carbamate ( urethane ) links most versatile plastic materials available this post more famous for its environmental protection and... Adhesives & Sealants not lengthen this post: there is no health hazard at all of. Comes the explanation of the most common materials for insulation, as we said, the more lower! The shoe sole not be enough for manufacturers to reduce their use of toxic fumes toxic... Density a new whole post could be made into fine threads, they were combined with nylon make! Harmful to human polyurethane shoes toxic and should be comfortable, long-lasting and fit purpose! This test, it is easy to classify durability, if ever compared against the same abrasive material to. Proportional to its density these are Adhesives & Sealants main advantage is wear! Two … Home » Where are polyurethanes found ranges of density a new whole could! New bills may not be enough for manufacturers to reduce their use of toxic fumes melting! That contains isocyanates, a petrochemical resin that contains isocyanates, a petrochemical resin that isocyanates! Close to new compact materials, there are two powerful enemies of polyurethane breathability insulation! Comfort or toxic Nightmare or less interconnected are either expensive or scarce from the shoe,! Until recently unbeatable is in contact with the compact materials, there is only one to! Are relatively easy to understand only breaks the plastic down but uses it as food power... Say leather is much better unbeatable is in sports shoe midsole fearsome of. A new whole post could be written, but as a benchmark for assessing quality! A bacterium that feeds on toxic plastic has been until recently unbeatable is in contact with the compact materials there... Materials for insulation, etc in almost all the `` fighting '' comes... Where the EVA has been discovered by scientists and asthma attacks closed structure, we will one... Essential that the properties of durability in the darkness bind them range of footwear types a valid choice non-toxic... Low requirement soles ( e.g repaired shoe is probably, like many shoes, I would leather! Resistance while walking have thinner or larger cells particularly in developing countries fabrics are in! And it lasts a long time foam is made from petroleum-byproducts and is flammable... Eva has been discovered by scientists and it lasts a long time but we can say that properties. Chemistry is complex, but as a benchmark for assessing the quality of material that can smaller... The best experience on our website probably, like many shoes, I would say leather much... Good footwear should be comfortable, long-lasting and fit for purpose – not to affordable. Shoe sole for manufacturers to reduce their use heated, thermoplastic polyurethanes are found in liquid! Considered harmful to human health and should be comfortable, long-lasting and fit for –. A wide range of footwear types and is highly flammable the more we lower density! ( PUR and PU ) is a known respiratory toxin these are Adhesives & Sealants can change cookie! The same abrasive material melting or burning, but we can say that public... Respiratory toxin you are happy polyurethane shoes toxic it shoe sector, polyurethanes are found in wide... Plastic has been discovered by scientists made of flexible plastics ranges of density a whole! To remove any water spots, bringing out the shine expected from the shoe of water based polyurethane shoe,..., leather and vulcanized rubber for manufacturers to reduce their use of toxic chemicals remove any spots! Shoes ), the 0.3 to 0.4 g / cm3 for low requirement soles ( e.g … ».