OTECH has a number of non-vinyl options for footwear applications have been developed and feature some very unique properties. The property enhancements from these OTECH compounds for shoe and boot designs, improve wear, surface appearance, weight and chemical resistance.
OTECH has several SBS and SEBS compounds being used in casual footwear applications including rainboots, utility boots and clogs. These compounds are a light-weight option that may replace some PVC applications.
OTECH has a new line of Cross-Linked, Expanded EVA compounds that are being sold into sandal, soling and boot applications. These compounded products offer the benefits of very light weights, with finished specific gravities as low as 0.3 post expansion, as well as superior wear and abrasion. OTECH also makes other cross-linked thermoplastic olefins that exhibit superior wear properties, slip resistance, and chemical resistance properties from the partial cross-linking of the finished products. Polyolefin elastomer compounds are also a growing option in other consumer goods applications.
The Durometer of a material used for midsoles and outsoles affects a shoe’s comfort, durability, and performance. Softer materials provide cushioning, flexibility, and slip resistance but wear faster and offer less responsiveness. Harder materials, on the other hand, increase durability, energy return, and abrasion resistance but reduce cushioning and traction.
Rebound measures how much energy a shoe returns after impact, expressed as a percentage of the force recovered after compression. Materials like PEBA or A-TPU offer excellent rebound, which helps propel runners forward and reduce fatigue. In walking or casual shoes, however, comfort and softness are usually prioritized over rebound.
Hysteresis describes energy lost as heat during each step. High hysteresis improves cushioning, shock absorption, and traction on slippery surfaces but causes more heat buildup and fatigue. Low hysteresis returns more energy and generates less heat, improving durability and efficiency. Thus, high-hysteresis materials suit walking or orthopedic shoes, while low-hysteresis materials are ideal for high-performance running footwear.
ASTM D4060 is the method used for Taber rotary abrasion testing. The test involves placing a 4 inch diameter circular specimen on a turntable, applying a specified load to two rotating abrasive wheels and measure how much weight is lost from the specimen after running for a specified number of cycles. OTECH has the capability to perform this testing.
DIN abrasion is performed using ASTM D5963. The test for this method involves preparing a sample of material and abrading it against a rotating drum that is covered in abrasive. The sample is abraded against the drum at a specified force for a set distance or time. The sample is weighed before and after testing and the results are expressed as a volume loss or relative abrasion resistance index. OTECH partners with an outside lab to perform this test.
ASTM F3445 footwear slip resistance testing is performed using ASTM F2913 whole shoe test method. The test uses an instrument known as a tribometer that is able to quantify the coefficient of friction of the shoe sole against wet, dry and oily surfaces. In order to be considered slip resistant a minimum of .040 must be achieved by both the sole and the fore portion of the shoe. OTECH partners with an outside lab to perform this testing.
Ross flex testing is performed using ASTM D1052 as the testing standard. A specimen is cut from the material being tested. A notch is cut into the specimen using a specialized tool. The specimen is loaded into a Ross flexing tester which repeatedly bends to sample to a 90 degree angle and back. At specified intervals, the length of the cut is measured and recorded to determine how much cut growth is taking place. The test is continued for a specified number of cycles or until the cut grows to a specified length. OTECH has the capability to perform this testing at ambient temperatures. If lower temperatures are required, we would partner with an outside lab.
PVC is inherently very resistant to sweat and salt making it an ideal choice for applications where this is a concern. TPE is generally resistant to sweat and salt which is why it is frequently selected for athletic footwear.
PVC is very resistant to water. This is why it is commonly used to manufacture water pipes and plumbing fixtures. With TPE, hydrolysis resistance is a bit more complicated. TPUs are good choices for applications where exposure to water is a concern. Styrene based TPEs typically have poor resistance to hydrolysis, though formulations can be developed with improved resistance. Choosing TPEs and TPUs with higher molecular weights and denser polymer networks will increase their resistance to hydrolysis.
PVC compounds are formulated to resist cracking in cold environments by selecting plasticizers that have linear molecular structures. Durometer also plays a key role as softer materials are more resistant to cold cracking than harder materials are. TPEs have an advantage when being used in low temperature environments as they have a good inherent resistance to low temperature. TPO, TPU and TPE-E can resist temperatures as low as -76F.
PVC offers a lot of versatility when it comes to designing footwear. It is durable and abrasion resistant in addition to being chemical resistant, especially when formulated using NBR or TPU based additives. It offers good heat and moisture insulation. Probably its most attractive feature is its cost effectiveness when compared with other polymers. It is easy to color offering many aesthetic choices when designing a shoe. Care must be taken when designing the tread pattern in order for it to be slip resistant. It is light weight when compared to leather, but not as lightweight as other polymers.
TPEs offer many characteristics that make them a preferred choice when making footwear products. TPE compounds can be as soft as a 5 Shore A Durometer for use in shock absorbent comfort insoles. TPEs are easily molded into complex shapes and are easily colorable, giving more artistic freedom to shoe designers. TPEs offer good chemical and abrasion resistance and can be formulated for superior slip resistance making them a good choice for industrial footwear applications. TPE has better thermal stability properties than PVC which makes them less difficult to manufacture.
More and more manufacturers are turning to cross linked expanded EVA for shoe production. The closed cellular structure of the material results in a light weight shoe that is durable yet comfortable and waterproof. This material offers superior shock absorption and energy return reducing strain on feet, joints, and muscles. EVA is relatively inexpensive when compared with other TPE/TPO compounds though not as economical as PVC. Many of the sandals and slides you see at major retailers are made entirely of XLEVA. It is also used for midsoles and insoles of high performance running shoes and workout recovery shoes. This material is easily colorable offering a variety of design choices.
TPEs can be formulated in a wide variety of hardnesses ranging from 20 Shore 00 (extremely soft gel like material) to 90 Shore D (rigid plastic). TPEs on the low end of this hardness scale are ideal for the production of soft shock absorbing inserts that enhance comfort and reduce fatigue. TPE is an excellent material for midsoles and outsoles. They can be customized to the desired hardness level and expansion ratio to optimize rebound and energy return. TPEs on the higher end of the scale are good candidates for structural elements like heel counters, shanks and lace eyelets.
At low temperatures TPE can lose its flexibility and become stiff and rigid. This can lead to cracking and also causes the material to lose its grip properties against a surface. This is why it is important to make sure that the material has the right amount of plasticizer or oil to ensure it will remain pliant at low temperatures. These plasticizers work by disrupting intermolecular forces that cause the material to stiffen when exposed to low temperatures. They increase the free volume by creating space between the polymer chains allowing them to move more freely in cold environments. They also reduce the glass transition temperature which is the point where the polymer transitions from a soft flexible state to a hard glassy one. By employing the proper amount and type of plasticizer, TPEs can remain flexible at temperatures as low as -70C.
All of OTECH’s TPE offerings for footwear compounds are ortho phthalate free. This means they are REACH, RoHS, and Prop 65 compliant. TPEs can easily be remelted and reformed which enables the use of regrind. For certain applications, regrind can be used at up to 30%. Use of dry pigments in TPEs can result in poor color dispersion which manifests itself as streaks of color being present in finished products. In order to achieve good color dispersion in our TPE products we partner with colorant masterbatch manufacturers to ensure uniform color dispersion in compounds and finished products.
4744 E. Oaknoll Road
Rolling Prairie, IN 46371
Phone: 219-778-8001
Fax: 219-778-8007
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