Preparation and Characterization of Talc Filled Thermoplastic Polyurethane/Polypropylene Blends

The effect of the addition of talc on the morphology and thermal properties of blends of thermoplastic polyurethane (TPU) and polypropylene (PP) was investigated. The blends of TPU and PP are incompatible because of large differences in polarities between the nonpolar crystalline PP and polar TPU and high interfacial tensions. The interaction between TPU and PP can be improved by using talc as reinforcing filler. The morphology was observed by means of scanning electron microscopy (SEM). The thermal properties of the neat polymers and unfilled and talc filled TPU/PP blends were studied by using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The addition of talc in TPU/PP blends improved miscibility in all investigated TPU/T/PP blends. The DSC results for talc filled TPU/PP blends show that the degree of crystallinity increased, which is due to the nucleating effect induced by talc particles. The reason for the increased storage modulus of blends with the incorporation of talc is due to the improved interface between polymers and filler. According to TGA results, the addition of talc enhanced thermal stability. The homogeneity of the talc filled TPU/PP blends is better than unfilled TPU/PP blends. 1. Introduction Blending has been widely and effectively used to modify or control the properties of polymer by appropriately compounding miscible polymers. Miscible polymer blends can create new materials with completely different properties, and fabricated articles may possess good mechanical properties. Thermoplastic polyurethanes (TPUs) are linear, segmented copolymers consisting of alternating hard segments (HSs) and soft segments (SSs). HSs, comprised of diisocyanate and short chain extender (CE) molecules such as diols or diamines, are rigid and highly polar. HSs have high interchain interaction due to hydrogen bonding between the urethane/urea groups. The hydrogen bonding associations within the HSs in TPUs act as a reinforcing filler for the soft matrix. On the other hand, SSs, formed from linear long-chain diols or polyols, are flexible and weakly polar [1]. Phase separation in TPUs occurs because of the thermodynamic immiscibility or incompatibility between the hard and soft phase. The degree of phase separation in Pus depends on the types of diisocyanate and polyol and polyol employed to produce the PU, type of polyfunctional compound used in the crosslinking process, NCO？:？OH ratio, size of HSs and SSs, and method of synthesis. Polypropylene (PP), a semicrystalline polyolefin