Blending with TPU

PVC has been widely used in every aspect of life. Its production has been refined and its quality is relatively stable. Unlike TPU, PVCs used in blending with TPU are almost exclusively from commercial sources. Most of them are made by suspension polymerization. 

BR and/or poly(ethylene-co- vinyl or acrylic monomer), e.g., EVAc EPDM polynorbornene having carboxylic, and carboxylic ester groups PVC blends with crosslinked NBR for foamed floating devices DOIP plasticized PVC blended with TPU and EVAc... 

POM was blended with 1-5 wt% of either PE, EVAc, PEG POM was blended with 90-99 wt% of LDPE PE or PP with EVAc and either POM, PMMA, PS or SMM POM was blended with EVAc and HOPE POM was first blended with TPU, then with either PA, LLDPE, PP, PBT or PET Burg et al., 1972 Rudin and Schreiber, 1964b Yamamoto et al., 1971 Ishida and Masamoto, 1974 Flexman, 1992... 

Impact modification of POM by blending with TPU, pentaerythritol and CORl T = 210°C, residence time t = 1-2 minutes Nagai et al., 1994... 

POM was first blended with TPU and then with either PA, LLDPE, PP, PBT, or PET Flexman 1992... 

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. 

For example, 5 to 20% acetal blended with TPU improves the overall processability of the TPU in extrusion and blow-molding applications. The blends of 30 to 50% acetal with TPU improve TPU s heat and humid age properties and solvent-resistance [41-43]. It was found that the higher the content of POM in the POM/TPU blend, the higher the heat distortion temperature (HDT) of the blend [44] (Figure 3). 

POM can be effectively toughened by blending with TPU. The improvement in toughness is most significant with TPU content from 20-30% due to the elastomer phase remains dispersed up to the content [45,46]. 

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. 

Based on this information, Lu and Macosko studied the compatibility of blends composed of functionalized PPs and TPU [107]. In this work, maleated PP (PP-g-MA), primary and secondary amine-functionalized PPs (PP-g-NH2 and PP-g-NHR, respectively) were blended with TPU. The compatibility of... 

Polyurethane engineering thermoplastics are also manufactured from MDI and short-chain glycols (49). These polymers were introduced by Upjohn/Dow under the trade name Isoplast. The glycols used are 1,6-hexanediol and cyclohexanedimethanol. 1,4-Butanediol is too volatile at the high processing temperatures used in the reaction extmsion process. Blends of engineering thermoplastics with TPU are also finding uses in many appHcations... 

Differential scanning calorimetry (DSC) is fast, sensitive, simple, and only needs a small amount of a sample, therefore it is widely used to analyze the system. For example, a polyester-based TPU, 892024TPU, made in our lab, was blended with a commercial PVC resin in different ratios. The glass transition temperature (Tg) values of these systems were determined by DSC and the results are shown in Table 1. 

Not all TPU polymers are suitable for blending with PVC. Certain types of TPUs when mixed with PVC produce a hard, deep-yellow colored material that whitens when bent [7]. Only a few types of TPUs are suitable for blending with PVC. 

Both polyester- and polyether-based TPU could be used to blend with PVC, although the former constitutes the majority of the commercial products. All of the blends should meet the following requirements (I) they must have good or relatively good compatibility with PVC, (2) their processing temperature should be close to or lower than that of PVC, (3) they have to meet the specific requirements of the products, for example, TPUs used for medical purposes should be colorless (if possible), transparent, nontoxic, and able to be sterilized, and (4) they should not be expensive. 

A series of polyester-based TPU (566TPU series) were synthesized in our lab and used to blend with PVC to manufacture a modified PVC material for medical uses [14]. Morphological studies showed that 566TPU has very good compatibility with PVC. Detailed mechanical and electronic property tests were also conducted. Some of the data are provided in Tables 3 and 4. 

High modulus blends can be developed by mixing TPU with acetal copolymer (trioxane ethylene oxide copolymers) [242-244]. The highly crystalline acetal forms a second continuous phase. Kumar et al. studied behavior of such blends [245]. TPU retains none of its physical properties after immersion in water at 70°C for three weeks. The hydrolysis resistance of TPU can be improved by blending with polycarbodiimides [246]. Two parts of carbodiimide with TPU offer 87% retention of its strength, 93% of elongation, and 75% of modulus under the same... 

A route to compatibility involving ionomers has been described recently by Eisenberg and coworkers [250-252]. The use of ionic interactions between different polymer chains to produce new materials has gained tremendous importance. Choudhury et al. [60] reported compatibilization of NR-polyolefin blends with the use of ionomers (S-EPDM). Blending with thermoplastics and elastomers could enhance the properties of MPR. The compatibility of copolyester TPE, TPU, flexible PVC, with MPR in aU proportions, enables one to blend any combination of these plastics with MPR to cost performance balance. Myrick has reported on the effect of blending MPR with various combinations and proportions of these plastics and provided a general guideline for property enhancement [253]. 

Because the components must initially form miscible solutions or swollen networks a degree of affinity between the reacting components is needed. Therefore, most of the investigations into epoxy IPNs have involved the use of partially miscible components such as thermoplastic urethanes (TPU) with polystyrenes [57], acrylates [58-61] or esters which form loose hydrogen-bound mixtures during fabrication [62-71 ]. Epoxy has also been modified with polyetherketones [72],polyether sulfones [5] and even polyetherimides [66] to help improve fracture behavior. These systems, due to immiscibility, tend to be polymer blends with distinct macromolecular phase morphologies and not molecularly mixed compounds. 

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. 

More recently, foamable, recyclable PVC blends were disclosed. They comprise PVC plasticized with DOP and/or epoxidized soybean oil, blended with either TPU and/or EVAc. The formulation could be foamed either during extrusion or injection molding. The material is used to produce anti-slip shoe soles with good abrasion resistance [Shin etal., 1998]. 

These systems are not of industrial importance. However, addition of an acrylic was reported to improve processability, abrasion resistance, and weatherability of POM. For example, to improve weatherability POM was blended with polythioisocyanate, TPU, PMMA, and benzo-triazole [Endo et al., 1990]. POM/TPU with EMMA and benzotriazole shown enhanced performance [Okuda, 1990]. POM was also blended... 

The polyester-type thermoset polyurethanes were commercialized in 1942, and the linear thermoplastic ones (TPU) ten years later. Polyester-type TPU, Texin resins for extrusion and injection molding, were introduced in 1961, whereas polyether-type, Roylar , in 1971. Owing to great diversity of the ingredients, the TPU performance can be readily modihed. Por this reason, as well as because of the cost, TPU s are seldom blended. Their use can be divided into three groups (i) blends with POM, (ii) blends in which TPU is used as a com-patibilizer and impact modifier, and (iii) others. 

Blends of PC/PET/TPU with EVAc-GMA and optionally MBS or ABS, have good flexural modulus, strength, weld line strength, solvent resistance, and impact behavior [Laughner, 1994]. PC blends with a polycaprolactone-polyurethane resin, TPU Pellethane , and either MBS or MBA showed similar behavior [Henton et al., 1993]. 

These blends are immiscible, thus should be compatibilized and toughened. Addition of POM to PC improves the solvent and chemical resistance [Miller, 1972], PC blends with POM and TPU were easy to mold into articles having high impact... 

PPS and PEEK blended with a fluoro(co)-polymers and reinforced with either CF or GF were wear resistant with a short break-in period for forming a self lubricating film [Davies and Hatton, 1994]. Many commercial blends contain fluoropolymers (primarily PTFE) for the improved weatherability, wear and solvent resistance SUPEC — self-lubricating blend of crystalline PPS with PTFE and 30 wt% GF, Lubricomp blends from LNP and similar/JTP blends from RTP Co. (e.g., 15 wt% PTFE, 30 wt% GF and any of the following resins ABS, PA, PEST, PC, PE, PEI, POM, PP, PPE, PPS, PS, PSF, PVDF, SAN, TPU, PEEK, PES, etc.), Sumiploy from Sumitomo Chem. Co., etc. [Utracki, 1994]. 

PC is also blended with a polyester urethane TPU (Texin 3000 PC/TPU, Texin 4000 TPU/PC). For these systems, screw machines are preferable with L/D = 15 and compression ratio = 2-3. 

Mixtures of polar polymers, such as PVC, PC, PMMA, TPU, PA, PEST, PGI, SAN, or ABS could be compatibilized by incorporation of two copolymers, the first containing vinyl alcohol, the second an anhydride. For example, blends of TPU with Phenoxy, EVAl, COPO, modified cellulose, and/or polyalkylene oxide, had attractive physical, optical and barrier properties, and were melt-processable without degradation. They could be transformed into films, sheets, or bottles with good barrier properties. Blends containing PA were used for films, tubes, toys, gears, bearings, shafts, curtain sliders, door rollers, etc. The blends with elastomers were reported suitable for improved wiper blades [La Fleur et al., 1994]. 

Binary blends containing a multiblock copolymer as one component or both components in the blend, in which a certain block of the copolymer is miscible with the other polymer, were also reported to be an effective way to fabricate SMP with desired properties. This type of SMP blend include the segmented thermoplastic polyurethane (TPU)/phenoxy resin blend and TPU/poly vinyl chloride (PVC) blend [26,27]. In the blends, the soft segment of the TPU is miscible with the phenoxy resin or PVC, and Tg of this miscible... 

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