TPU blends

The effects of added DOP on the properties of PVC/ TPU blending material are shown in Table 2. 

Table 2 The Effect of Added DOP on the Mechanical Properties of PVC/TPU Blends...

Zhong et al. [12] also studied the plasticizing properties of the PVC/TPU blending system by measuring the torque (TQ) during plasticating. 

Several commercial products of PVC/TPU blends are available. The BF Goodrich Chemical Group has a PVC/ TPU blend based on their Estane series TPUs. For example, their Estane 54620, a polyester-based TPU with a °ShA 85 hardness, shows excellent compatibility with flexible PVC. The blends are produced by mixing PVC, TPU, plasticizer, stabilizer, and lubricant in a twin-screw extruder. These polymeric blends show intermediate mechanical properties between PVC and TPU. 

The method of filler incorporation also determines its distribution between the phases. When PE/TPU blend was in the molten state when mixed with carbon black, the island morphology was obtained with carbon black mostly resident in one phase. Mixing at room temperature followed by cold molding (50°C) resulted in the mixture with uniformly distributed carbon black. ... 

Table 6. Effect of Dissimilar Chain Extenders In TPU Blends.

Initially, two-component, PVC/TPU blends were proposed [B. F. Goodrich Co., 1960], but soon, PVC/TPU blends with a modifier, e.g., ABS [Waugaman et al., 1963] NBR or PA [Kepes, 1959] were disclosed. Blending was also carried out by mixing PVC with polyols and isocyanates then polymerizing these two [Dainichiseika Color Chemicals, 1983]. Commercial PVC/TPU (with NBR) are represented by Duralex . The materials are usually formulated for extrusion, e.g., for wire and cable insulation, hoses and packaging. 

The oldest and most common method of POM toughening is by incorporation of TPU. Delrin POM/TPU blends were commercialized in 1960. The others followed, e.g., Celcon , Duraloy , Formaldafil , Fulton KL, Hostaform , RTP 800, TC, or Ultraform . These alloys have high impact strength and elastic recovery that depend on composition, morphology, as well as on the compounding and processing methods. Examples of these blends are listed in Table 1.66. 

PA/TPU blends have been compatibilized by addition of a bis-isocyanate coupling agent that is capable of reacting with nucleophilic end-groups on both polymers to form a block copolymer. Franke et al. [1993] have extruded PA-6 (20-0 parts) with polyester-urethane (78-100 parts) using a TSE at 230°C in the presence of 0.5-2 parts diphenylmethane dusocyanate. The coupling agent was added downstream of the extmder feed-throat. The blends were characterized by TEM, SEC, DSC, DMA, and FTIR. 

ABS/TPU blends are used mostly for automotive parts, e.g., paintable, soft bumper fascias. They are mosfly formed by injection molding or extrusion. 

A recent commercial blend of ABS contains thermoplastic polyurethane elastomer as the main blend component. The blend was introduced in 1990 by Dow Chemical Co., under the trade name Prevail . These blends characteristically exhibit low modulus (340 to 1000 MPa) and high impact strength at low temperamres, e.g. notched Izod values of 370 to 1500 J/m at -29°C. The TPU component of the blend imparts high toughness and also allows paintabihty without a primer. ABS component imparts heat resistance (for paint ovens) and good tensile strength in the blend. The blend is projected to find applications in the automotive markets, particularly as paintable, soft bumper fascias. Typical properties of commercial ABS/TPU blends are shown in Table 15.6. 

Poomalai, P, and Siddaramaiah. 2005. Studies on p>oly (methyl methacrylate) (PMMA) and thermoplastic polyurethane (TPU) blends. Journal of Macromolecular Science, Part A—Pure and Applied Chemistry 42 1399-1407. 

Ma et al. (2012b) reported compatibilized PVDF-TPU blends comprising PVDF-g-acrylic acid. Farah and Lerma (2010) prepared hydroxy-functionalized PP by reaction of PP-g-M A with 2-aminoethanol and used this fimctionalized PP in blends with TPU and unfunctionalized PP. Ethylene-octene copolymer was also used in place of PP. 

Qureshi (2009) prepared PP/TPU blends compatibilized using an amine-functionalized PP, which functionalized PP had been prepared in a separate step by extrusion of PP-g-MA with either hexamethylenediamine or dodecamethyl-enediamine. Blends characterization techniques included SEM, rheology, and mechanical properties. 

Lu and Macosko (2004) and Lu et al. (2003) have prepared compatibilized blends of polyurethane with functionalized PP characterizing the blends by rheology, DMA, tensile properties, and morphology. Primary and secondary amine-functionalized PP were more efficient compatibilizers than was PP-g-MA. A degradative mechanism for copolymer formation involving polyurethane chain cleavage was postulated. See also Kobayashi et al. (2011) for related PE/TPU blends. 

With regard to reactively compatibilized TPU blends, Lu et al. (2002) determined the relative reactivity of various functionalities toward TPU using model compounds. The ranking of relative reactivity was found to be primary amine (most reactive) > seccmdaiy amine >> hydroxyl carboxylic acid anhydride >> epoxide (least reactive). 

---