Blends of TPU with other Thermoplastics

TPU can be blended with PVC combining the toughness and abrasion resistance of the TPU with the stiffness and high modulus of PVC together with cost reduction of TPU. Chlorinated polyethylene can also be used as a blend with TPU or with TPU plus PVC or with polyethylene in the latter case the chlorinated polyethylene acts as a carrier for the very incompatible polyethylene. Styrene-acrylonitrile copolymers (SAN) and the rubber-modified versions, ABS, have also been blended with thermoplastic polyurethanes. Again the stiffness and initial modulus are improved without much sacrifice of the low-temperature properties. 

Soft polyurethane rollers (from about 15 IRHD to about 55 IRHD) have been in use for many years, mainly in the printing industry. These polyurethanes are generally made by a one-shot technique and are usually based on polyesters chain-extended with TDI. They are one-phase amorphous elastomers with very low compression set ( 10%) and good ink and solvent resistance. Harder polyurethane rollers are also used from about 55 IRHD to about 95 IRHD for more demanding mechanicalhandling applications, for example, in the steel, textile and paper industries. 

These elastomers are the normal two-phase block copolymers made from either MDI prepolymers and diols or TDI prepolymers and MOCA. Although having a higher compression set (usually 30%), these harder elastomers have outstanding wear and abrasion resistance and have a significantly longer life than conventional steel or other rubber rollers. 

---