The influence of filler treatment on the properties of TPU/PP blends: I. Thermal properties and stability

Commercially available organosilane (3‐glycidoxypropyltrimethoxysilane (GPTMS)) coupling agent was used to treat talc in order to improve the affinity relative between the filler and the polymer in composites as well as filler and polymer in the thermoplastic polyurethane/polypropylene (TPU/PP) blends (talc content was 5 wt%). The talc particles were first modified with GPTMS and then introduced into TPU, PP as well as TPU/PP blends with different weight ratios of polymers using blending method and subsequently injection molded in a hydraulic press. The aim was to report the effect of silane coupling agent on the thermal and morphological properties of talc filled composites and blends. The results showed that the thermal properties of the TPU, PP composites and TPU/PP blends were improved with the addition of silane treated talc (higher melting (T_m), crystallization (T_c) temperatures and degree of crystallinity (χ_c)). The glass transition temperature (T_g) obtained by dynamic mechanical analysis (DMA) of the TPU soft segments in TPU/PP blends increased with the addition of untreated and silane treated talc due to lower mobility of the soft segments in TPU and better miscibility of TPU and PP. TPU/PP blends with the silane treated talc show better thermal stability than the TPU/PP blends with untreated talc. POLYM. ENG. SCI., 55:1920–1930, 2015. © 2014 Society of Plastics Engineers     

Different approaches for creating nanocellular TPU foams by supercritical CO<Subscript>2</Subscript> foaming

In this study, three different approaches were applied to obtain thermoplastic polyurethane (TPU) nanocellular foams. The TPU was synthesized with a 4, 4′-methylenebis (phenyl isocyanate) and 1, 4-butanediol (MDI/BD) hard segment system using a pre-polymer method. The three approaches included increasing the hard segment content, adding a graphene nucleation agent, and replacing the soft segments. Although the synthesized TPUs had a different hardness, it was possible to obtain nanocellular structures with all of the methods. The cell structure is not a function of hardness only. Crystallinity affects the cell structure as well. The addition of graphene and replacement of the soft segments were more effective at yielding nanocellular foams. Our best results showed that after adding 0.1 wt% of graphene, the average cell size of the TPU foam decreased to 715 nm, and the cell density was improved to 4.94 × 10¹¹ cells/cm³. The relative density of the foam could be as low as 0.77. This study first reported elastomer-based nanocellular structures with such low relative density.     

TPU对ABS熔融沉积成型性能的影响

采用熔融共混制备丙烯腈-丁二烯-苯乙烯共聚物/热塑性聚氨酯（ABS/TPU）3D打印耗材,通过熔融沉积成型（FDM）制备标准测试样条,并对ABS/TPU体系的成型性能、力学性能、微观结构、流变性能进行研究。结果表明,TPU改性ABS的成型性能均优于未改性ABS,当TPU质量分数大于20 %时,成型过程不发生翘曲收缩现象;同时有较好的力学性能,缺口冲击强度为18.81 kJ/m2比纯ABS提高了95.94 %,拉伸强度为32.92 MPa,下降了8.5 %;TPU质量分数大于20 %时,材料发生韧性断裂,并随TPU的增加,断面粗糙程度增加,有空洞现象;ABS/TPU具有较好的相容性,且随TPU含量增加,ABS/TPU分子链扩散能力增加。     

Effect of TPU hard segment content on the rheological and mechanical properties of PLA/TPU blends

Blends of an amorphous polylactide (PLA) with three different thermoplastic polyurethane (TPU) grades having various hard segment (HS) contents are prepared at the blending ratio of 85/15 wt% through a twin-screw extruder (TSE) at processing temperatures of 150 and 190°C. Blends of a semicrystalline PLA with 15 wt% of the noted TPU grades are also processed in the TSE at 190°C to investigate the matrix crystallization effect on the morphology and property enhancements. The rheological experiments reveal that the increase in TPU HS content significantly increases the phase compatibility between PLA and TPU as also suggested by the finer morphology of the TPU phase, although the use of lower HS TPUs is more favorable to enhance the ductility and impact properties of the blends.     

The effect of nanoclay on the crystallization behavior,microcellular structure,and mechanical properties of thermoplastic polyurethane nanocomposite foams

The effects of nanoclay on the crystallization behavior, microcellular structure, and mechanical properties of thermoplastic polyurethane (TPU)/clay nanocomposite (TPUCN) foams were investigated using differential scanning calorimetry, rheometry, scanning electron microscope, transmission electron microscopy, and X‐ray diffraction. It was found that the nanoclay acted as an effective nucleating agent for both crystal nucleation and cell nucleation. As a result, it significantly enhanced the crystallization behavior of the hard segment (HS) domains in TPU while refining the foamed structure of the microcellular injection molded parts. In particular, the average cell diameter of TPUCN foams decreased from 45 µm for neat TPU to 27 µm for TPUCN5 (5 wt% clay) and 18 µm for TPUCN10 (10 wt% clay). Furthermore, the cell density increased from 0.7 × 10⁷ cell/cm³ for neat TPU to 1.4 × 10⁷ cell/cm³ and 3.1 × 10⁷ cell/cm³ for TPUCN5 and TPUCN10, respectively. In addition, the tensile strength also increased by 56.3% and 89.2% with 5 and 10 wt% clay content, respectively. By controlling the cell nucleation behavior through uniformly dispersed nanoclay, this study demonstrates that it is feasible to produce TPUCN foams via microcellular injection molding with desirable microcellular structures and improved mechanical properties. POLYM. ENG. SCI., 56:319–327, 2016. © 2015 Society of Plastics Engineers     

热塑性聚氨酯对膨胀型阻燃聚丙烯的增容作用

热塑性聚氨酯（TPU）含有氨基甲酸酯链段,该结构有利于受热成炭,提高阻燃性能,又可以通过超分子间力与膨胀型阻燃剂（IFR）作用,而TPU的软段与聚丙烯（PP）结构相似,因此可作为PP/IFR体系的增容剂.力学性能和阻燃性能测试表明,3%TPU的加入,使材料的拉伸和冲击性能分别提高了9.8%和16.6%,离火自熄时间由45s降低到25 s;在TPU添加量为4%时,材料的冲击性能提高显著,已经达到纯PP的水平.流变性能测试结果表明,在测试温度下,由于TPU软化点较低,而IFR中季戊四醇（PT）又处于熔化状态,加入TPU和IFR使粘度降低,但加入量增加到5%时,体系粘度增大,说明TPU对体系起到了增容作用.SEM微观形态分析表明,随TPU含量增大,IFR与PP界面作用力增强,断裂由发生在IFR与PP的界面,变为发生在底材内部,说明TPU对体系起到了增容的作用.事实证明TPU是PP/IFR共混体系有效的增容剂.     

Study on thermoplastic polyurethane/polypropylene (TPU/PP) blend as a blood bag material

Blends with different ratios of thermoplastic polyurethane/polypropylene (TPU/PP) were prepared by melt mixing using an internal Haake mixer. Properties of the blends were investigated using SEM micrographs of cryofractures and measurement of the mechanical strength, water absorption, cell culture, and platelet adhesion in vitro tests, which were compared with those of PVC blood bags. The effect of the addition of the ethylene–vinyl acetate (EVA) copolymer on the TPU/PP blend properties was investigated. The results indicated that a TPU/PP/EVA = 80/20/5 blend can be used as a new blood bag material. It was observed that the blend is homogeneous with higher mechanical strength than that of the commercial PVC blood bag. This blend also showed a compatible cell response in contact with L929 fibroblast cells and fewer tendencies to interaction with platelets compared to the PVC blood bag. Although the blends were immissible and no chemical reaction at the interface could be found, the blood compatibility of the blends were improved. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2496–2501, 2003     

Studies on polymer blends with moderate specific interactions. 2. phase structure of blends SAN/TPU and SAN/TPU/EVA

This paper deals with morphological studies of binary and ternary blends composed of poly(styrene-co-acrylonitrile) (SAN), polyurethane elastomer (TPU) and poly(ethylene-co-vinyl acetate) (EVA). Selective etching was found necessary to expose the morphologies of the blends. Chloroform or hot acetone, hexane/toluene (2/1v/v) and NaOH/CH₃OH (1wt%) were found to be selective etching agents for SAN, EVA and TPU, respectively. SAN and TPU form blends with fine dispersion structure, while SAN and EVA lead to rough phase structure with poor phase adhesion. These results are in accordance with the difference in the mechanical properties of SAN/TPU and SAN/EVA. In addition, for SAN/TPU/EVA blends, if TPU is only a minor component, it is preferentially located at the interphase, playing the role of a compatibilizer. As the amount of TPU increases, the compatibility is gradually improved. ©1997 SCI     

TPU/PLA blend foams: Enhanced foamability,structural stability,and implications for shape memory foams

A series of thermoplastic polyurethane (TPU)/poly(lactic acid) (PLA) blends are studied in terms of morphological, thermal, and rheological properties by scanning electron microscopy, differential scanning calorimetry, and rheometry. Using supercritical CO₂ batch foaming, the foamability of the blends is systematically investigated. It is found that the 80/20 (wt %/wt %) TPU/PLA blend (TPU80%) shows vastly enhanced foamability over a wide range of foaming conditions to produce foams with a myriad of cellular morphology. The foamability enhancement results from the improved cell nucleation and growth, and the changes in the polymer microstructure. Compared to elastic TPU foams, the TPU80% retain their shapes 3.4 times better. Mechanism for the enhanced stability is proposed and verified using Kohlrausch–Williams–Watts model. The materials developed in the study and the mechanistic understanding of the shape fixation process may facilitate the advancement of elastomeric foams in conventional use as well as in novel shape memory applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47416.     

Compatibilization and properties of ethylene vinyl acetate copolymer (EVA) and thermoplastic polyurethane (TPU) blend based foam

Ethylene vinyl acetate copolymer/thermoplastic polyurethane (EVA/TPU) blending foams are rarely reported so far because of their poor compatibility, and addition of a compatibilizer to the blend system was our major interest, which can improve interfacial adhesion between the two phases. In this paper, TPU-grafted EVA (EVA-g-TPU), as a compatibilizer, was simply prepared using maleic anhydride-grafted EVA (EVA-g-MAH) and 4,4′ diamino diphenyl methane in the mixing process of TPU and EVA matrix. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to investigate the structures of EVA-g-TPU and the interfacial reaction in the mixing process, and the effect of EVA-g-TPU on compatibilization between the two phases of EVA/TPU blends was investigated using scanning electron microscopy. Finally, EVA/EVA-g-TPU/TPU foams based on the good compatibility of the resin blends were prepared, and the physical properties directly related to the compatibility were investigated as a function of the theoretical quantity (molar mass) of EVA-g-TPU (n _EVA-g-TPU) in the foams. Moreover, the tensile strength, elongation at break, tear strength and compression set were improved by 19.0, 9.3, 43.6 and 7.5 %, respectively. Overall, EVA/EVA-g-TPU/TPU foams with excellent mechanical properties were obtained without sacrificing other important physical properties (lower density etc.) through popular and friendly means in this research.     

微胶囊红磷在TPU阻燃系统中的应用

采用国产TPU、CPE,在TPU/CPE二元共混改性体系中添加阻燃合金HT 951,对所构成的TPU阻燃体系进行研究。实验表明:TPU/CPE/HT 951阻燃体系可达到FV 0级(HT 951=10phr),具有很好的阻燃性能;同时拉伸强度保持了纯TPU的71%,断裂伸长率保持了纯TPU断裂伸长率的87%,具有较好的力学性能;加工性能也随着阻燃剂份数的增加有一定的改善。     

Comparing the compatibility of various functionalized polypropylenes with thermoplastic polyurethane (TPU)

Three functionalized polypropylenes (PP), a maleated PP (PP-g-MA), primary amine functionalized PP (PP-g-NH₂), and secondary amine functionalized PP (PP-g-NHR), were melt blended with a thermoplastic polyurethane (TPU) at different compositions. Compatibility of each functionalized PP with TPU was compared by investigating the binary blends using rheological (mixer torques, dynamic shear rheometry), thermal (dynamic mechanical analysis), mechanical (tensile test), and morphological (scanning electron microscopy with image analysis, particle size analysis) measurements. Compatibility of the three functionalized PP's with TPU is ranked in a decreasing order as follows: PP-g-NHR≥PP-g-NH₂?PP-g-MA, which is attributed to higher reactivity of amine (primary and secondary) with urethane linkages. Accordingly, the TPU blends with the two types of amine functionalized PP's exhibited much better synergy, as reflected by much improved mechanical properties including higher tensile strength and ultimate elongation, and finer and more stable morphologies.     

Thermoplastic polyurethane/polypropylene blends based on novel vane extruder: A study of morphology and mechanical properties

Thermoplastic polyurethane (TPU) polypropylene (PP) blends of different weight ratios were prepared with a self‐made vane extruder (VE), which generates global dynamic elongational flow, and a traditional twin‐screw extruder (TSE), which generates shear flow. The mechanical properties, phase morphology, thermal behavior, and spherulite size of the blends were investigated to compare the different processing techniques. Samples prepared with a VE had superior mechanical properties than the samples prepared with a TSE. Scanning emission micrographs show that the fiber morphology of the TPU/PP blends (<60 wt% TPU) was improved by elongational flow in VE. Differential scanning calorimetry curves indicate that a dynamical elongational flow could improve the miscibility of the TPU/PP blends. The U‐shaped spherulite size curve indicates the changes in the spherulite size, as observed from a polarization microscope. Interlocked spherulites also reveal the apparent partial miscibility of the TPU/PP blends under elongational flow. POLYM. ENG. SCI., 54:716–724, 2014. © 2013 Society of Plastics Engineers     

Dynamic mechanical properties of nanoclay filled TPU/PP blends with compatibiliser

Abstract

Blends of thermoplastic polyurethane (TPU) and polypropylene (PP) are highly incompatible because of large differences in polarities and high interfacial tensions. On one hand, PP is added to TPU to improve TPU's thermal stability, chemical properties, mechanical properties (modulus, strength and hardness) and processing performance and to reduce TPU's cost. On the other hand, TPU is blended with PP to improve PP's properties (e.g. abrasion, flexibility, tear strength, shock absorbing capabilities, impact strength, adhesion and paintability/printability). Earlier works in polyurethane/organoclay nanocomposites, PP/organoclay nanocomposites and TPU/PP blends were studied. In our experimental work, both ester and ether based TPU nanocomposites were prepared by melt blending using 3?wt-% Cloisite 10A (organically modified montmorillonite clay) as the nanoscale reinforcement and blended with PP with/without PP-graft-maleic anhydride as the compatibiliser. Blends of nanoclay filled TPU/PP were evaluated for dynamic mechanical properties such as storage modulus E′, loss modulus E″ and dissipation factor tanδ.     

含异氰酸酯基的低聚物和聚醚增容改性POM/TPU共混物

利用双螺杆挤出机制备了聚甲醛(POM)/热塑性聚氨酯弹性体(TPU)、POM/TPU/含异氰酸酯基的低聚物(Z)以及POM/TPU/Z/聚醚3种共混物。采用力学性能测试、差示扫描量热分析(DSC)、偏光显微镜(PLM)、傅里叶转换红外线光谱 (FTIR)、扫描电子显微镜(SEM)、动态力学性能分析(DMA)等,研究了3种共混物的力学性能、结晶行为及形态结构。结果表明：共混物的缺口冲击强度和断裂伸长率随TPU含量的增加而提高;异氰酸酯基低聚物（Z）和聚醚在促进分散相分散、增强两相间的相容性方面发挥重要作用,降低了聚甲醛的结晶度,能够有效地提高共混物的缺口冲击强度和断裂伸长率。     

TPU增韧改性PBT的研究

分别采用醚型和酯型热塑性聚氨酯(TPU)对聚对苯二甲酸丁二醇酯(PBT)进行增韧改性，并对共混物的性能、形态结构及流变性能进行了研究。结果表明：醚型TPU对PBT有较好的增韧效果，共混物有明显的两相，PBT为连续相，TPU为分散相，当m(PBT)／m(TPU)=100／75时，拉伸屈服强度可达41．7MPa，缺口冲击强度326 J／m，是纯PBT的两倍，断裂伸长率330％；醚型TPU对PBT共混物的表观粘度有较大的影响，当m(PBT)／m(TPU)=100／50时．共混物表观粘度只有纯PBT的20％。     

Open‐cell polypropylene/polyolefin elastomer blend foams fabricated for reusable oil‐sorption materials

The fabrication of high‐performance oil sorbents is of great significance for oil spill cleanup. The main objective of this study was to prepare open‐cell polypropylene/polyolefin elastomer (PP/POE) blend foams for fabrication of reusable sorbents for oil sorption. Open‐cell PP/POE blend foams were prepared via continuous‐extrusion foaming using supercritical carbon dioxide as the blowing agent. The interconnected open‐cell structure was characterized by scanning electron microscopy. The hydrophobicity and lipophilicity of PP/POE open‐cell foams were revealed by tests of contact‐angle measurement, water and cyclohexane sorption on the foam surface, CCl₄ and cyclohexane sorption in water, and oil/water separation. Further, the sorption tests indicated that PP/POE blend foams showed larger oil‐uptake capacities than pure PP foams. In addition, cyclic compression tests showed that PP/POE open‐cell foams had excellent ductility and significantly improved recoverability compared to pure PP foams. In cyclic sorption–desorption tests, the sorption kinetics was studied in terms of capacity and saturation time, showing that PP/POE foams kept larger sorption capacities for 10 cycles, with larger sorption rates and good reusability. Based on the high open‐cell content, the good hydrophobic and oleophilic properties, the high oil‐sorption capacity, the improved recoverability, the large sorption rate, and the good reusability in cyclic oil‐sorption performance, the PP/POE open‐cell foams have shown promise as potential oil sorbents in applications for oil spill cleanup. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43812.     

PP/EPDM-g-MAH/TPU共混物流变行为的研究

以EPDM g MAH为增容剂 ,采用熔融共混技术制备了热塑性聚氨酯弹性体 (TPU)增韧聚丙烯 (PP)材料 ,研究了PP/EPDM g MAH/TPU共混物的流变行为 ,重点讨论了增容剂EPDM g MAH对共混物流变行为的影响。结果表明 :共混物熔体的非牛顿指数n <1,且随EPDM g MAH用量的增加而减小 ,表观粘度随剪切速率和剪切应力的增大而降低 ,熔体符合假塑性流体的流动规律 ;温度升高 ,表观粘度降低 ;随着EPDM g MAH用量的增加 ,共混物的表观粘度升高 ,粘流活化能有所减小     

Brittle‐Ductile Transition and Toughening Mechanism in POM/TPU/CaCO3 Ternary Composites

Summary: Polyoxymethylene (POM)/elastomer/filler ternary composites were prepared, in which thermoplastic polyurethane(TPU) and an inorganic filler, CaCO₃, were used to achieve balanced mechanical properties of POM. A two‐step processing method, in which the elastomer and the filler were mixed to a masterbatch first and then the masterbatch was melt‐blended with pure POM, was used to obtain a core‐shell microstructure with CaCO₃ covered by TPU. A brittle‐ductile transition phenomenon was observed with increasing TPU content for this ternary system. To better understand the toughening mechanism, we investigated the fractured surface, interparticle distance, and the spherulite size of POM as function of the TPU and CaCO₃ content. The critical TPU content depended on not only the content of CaCO₃, but also the size of CaCO₃ particles. The observed brittle‐ductile transition was discussed based on the crystallinity and spherulite size of POM as well as Wu's critical interparticle distance theory. The results showed that the impact strength of POM/TPU/CaCO₃ ternary system depends on a critical, interparticle distance, which varies from one system to another. The dependence of the impact strength on the spherulite size was considered for the first time, and a single curve was constructed. A critical spherulite size of 40 micron was found, at which brittle‐ductile transition occurs, regardless of the TPU and CaCO₃ content or the size of CaCO₃ particles. Our results indicate that the spherulite size of POM indeed plays a role in determining the toughness, and must be considered when discussing the toughening mechanism.

Izod impact strength vs. the crystal size for POM/TPU blends and POM/TPU/CaCO₃ ternary composites.     

Fire performance and mechanical properties of phenolic foams modified by phosphorus-containing polyethers

Two kinds of novel phosphorus-containing polyether toughening agents were synthesized and characterized by ¹H nuclear magnetic resonance (¹H NMR) and Fourier transform infrared spectra (FTIR). Afterwards, a series of phenolic foams with different loadings of phosphorus-containing toughening agents were prepared. The apparent density and scanning electron microscopy (SEM) results showed that the addition of 5 wt% toughening agents increased the expansion ratio and promoted the formation of uniform cells. The limiting oxygen index (LOI) values of modified phenolic foams decreased with the increase of modifier content, but it still remained at 40% even if the amount of modifier loadings was 10 wt%. UL-94 results showed all samples can pass V0 rating, indicating the modified foams still have great flame retardance. Microscale combustion calorimetry (MCC) results indicated that the peak heat release rate (PHRR) and total heat release (THR) of the modified foams were reduced by 42% and 35%, respectively, compared to the pure phenolic foams. Moreover, the thermal stability of samples was investigated by thermogravimetric analysis (TGA). The mechanical properties were evaluated and correlated with composition and structural features.