The Effects of Thermoplastic Polyurethane on the Structure and Mechanical Properties of Modified Polypropylene Blends

applied sciences

Article The Effects of Thermoplastic Polyurethane on the Structure and Mechanical Properties of Modiﬁed Polypropylene Blends

Ting An Lin 1, Ching-Wen Lou 2,3,4,5 and Jia-Horng Lin 4,5,6,7,8,9,*

1 Laboratory of Fiber Application and Manufacturing, Department of Fiber and Composite Materials, Feng Chia University, Taichung 40724, Taiwan; [email protected] 2 School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China; [email protected] 3 Graduate Institute of Biotechnology and Biomedical Engineering, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan 4 Department of Chemistry and Chemical Engineering, Minjiang University, Fuzhou 350108, China 5 College of Textile and Clothing, Qingdao University, Qingdao 266071, China 6 Department of Fiber and Composite Materials, Feng Chia University, Taichung 40724, Taiwan 7 Innovation Platform of Intelligent and Energy-Saving Textiles, School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China 8 School of Chinese Medicine, China Medical University, Taichung 40402, Taiwan 9 Department of Fashion Design, Asia University, Taichung 41354, Taiwan * Correspondence: [email protected]; Tel.: +886-4-2451-0871

Received: 25 October 2017; Accepted: 29 November 2017; Published: 3 December 2017

Abstract: In this study, a melt-compounding process was used to produce ordinary polypropylene (PP)/thermoplastic polyurethane (TPU) blends and modified impact-resistant polypropylene (MPP)/TPU blends. The influences of TPU on the blending morphology, melting behavior, crystallization behavior, and mechanical properties of these blends were investigated. Differential scanning calorimetry results show that using TPU influences the crystalline and melting behavior of PP/TPU blends, but not of MPP/TPU blends. X-ray diffraction analysis indicated that the presence of TPU neither influences the crystalline structure of PP nor creates new crystalline peaks. The mechanical property test results revealed that PP/TPU blends demonstrate better tensile strength, Young’s modulus, and flexural strength, whereas MPP/TPU blends exhibit higher energy absorption and impact strength. This study is expected to produce optimal products with the preferred continuous and dispersive phases for end users, designing multiple and compatible functionalities of blends.

Keywords: polymer composites; polypropylene; modified polypropylene; thermoplastic polyurethane; impact strength; melt-blending method

1. Introduction Polypropylene (PP) is a commonly used plastic material composed of semi-crystalline polymer and exhibits easy processing, chemical resistance, high rigidity, light weight, and a reasonable, relatively low cost [1,2]. However, PP has some disadvantages, such as a large shrinkage ratio, great brittleness at low temperature, and low impact resistance, and thus its development is limited. There are two effective methods of improving the low impact resistance. One method is to modify the PP copolymer by adding ethylene polypropylene rubber (EPR) or multiple-side-chained ethylene groups to enhance the impact resistance of PP-based blends. The other method is to blend elastomer with PP, obtaining synergistic impact strength [3]. The blending of polymers has gained much attention in both industrial and academic ﬁelds. A single speciﬁc polymer, or more than one polymer, can be added to polymer blends in order to

Appl. Sci. 2017, 7, 1254; doi:10.3390/app7121254 www.mdpi.com/journal/applsci Appl. Sci. 2017, 7, 1254 2 of 8 acquire certain properties. Thermoplastic polyurethane (TPU) is a polymer composed of both a hard segment (HS) and a soft segment (SS). An HS consists of urethane groups, while a SS consists of a polyol that includes ester groups or ether groups. TPU is featured as having an elasticity of rubber as well as high mechanical properties of plastic materials [4–6]. Therefore, using TPU effectively improves the mechanical properties and impact strength [7]. Bajsic et al. indicated that TPU/PP blends with 80 wt% TPU and 20 wt% PP resulted in poor mechanical properties, and the tensile strength, elongation at break, and Young’s modulus were 17.4 MPa, 7.0%, and 645.3 MPa, respectively. These results can be attributed to the immiscibility and incompatibility between PP and TPU, which led to an inhomogeneous phase with poor interaction [8]. Qu et al. examined the mechanical properties of TPU/PP blends with various contents of TPU (10–90 wt%) and found that a U-shaped mechanical property curve formed when TPU content increased. The test results indicated that the tensile strength of blends was signiﬁcantly dependent on the blending ratios. Moreover, due to a weak phase interaction and the disruption of TPU interchange hydrogen bonding, a minimum tensile strength was revealed with respect to blends with 60 wt% TPU and thus led to the propagation of cracks at the weak phase. In addition, the impact strength was obviously improved by a higher content of TPU, indicating that stress could be effectively transferred by a strong interface [9]. Therefore, the blending ratio of TPU and PP played a key role in the mechanical properties of the blends, such as tensile strength, elongation at break, Young’s modulus, and impact strength. In this study, PP and modiﬁed impact-resistant polypropylene (MPP), the former of which is a homopolymer and the latter of which is an impact copolymer, were used as the polymer matrix. MPP was expected to reduce the amount of TPU since TPU is an expensive polymer material. In most references, the blending ratios were set at 80:20, 70:30, and 50:50 for PP and TPU, and the mechanical properties of the PP/TPU blends were further discussed. Our results indicated that the tensile properties of PP/TPU blends decreased as more TPU was added. Some problems resulted from the larger intrinsic structure of TPU and from interphase interaction and transformations [8], so the proportion of TPU was set at 10 wt%. In the meantime, the pure PP and pure MPP were used as control groups, and the effects of using TPU on the blending morphology, melting behavior, crystalline behavior, and mechanical properties of polymer blends were investigated.

2. Experimental

2.1. Materials Polypropylene (PP, YUNGSOX 1080, Formosa Plastics Corporation, Taipei, Taiwan) is a homopolymer that has a density of 0.90 g/cm3 and a melt index of 10 g/10 min (ISO1133). Modiﬁed impact-resistant polypropylene (MPP, J-750HP, Prime Polymer Co., Ltd., Tokyo, Japan) is a copolymer that has a density of 0.91 g/cm3 and a melt index of 14 g/10 min (ISO1133). Thermoplastic polyurethane (TPU, HE-3285ALE, Headway Polyurethane Co., Ltd., Hsinchu, Taiwan) is an ester-type copolymer that has a density of 1.23 g/cm3 and a melt index of 7.03 g/10 min (175 ◦C, 2.16 kg).

2.2. Preparation PP/TPU and MPP/TPU blends were made using a melt-compounding process. The blending ratios for both PP/TPU and MPP/TPU blends were 90:10 (90 wt% of PP or MPP and 10 wt% of TPU). A single-screw extruder (SEVC-45, Re-Plast Extrder Corp., Miaoli, Taiwan) was used for melt-compounding. The temperature parameters of the barrels were 200, 210, 210, and 210 ◦C, and the rotary speed was 25 rpm. The schematic diagram of the manufacturing process is shown in Figure1. The PP/TPU polymer melts were drawn and cooled in a water bath to make them uniform and evenly mixed. The resulting samples were PP90/TPU10 and MPP90/TPU10 blends. The blends were processed using an injection mold in order to form different blends. PP100 and pure MPP100 Appl. Sci. 2017, 7, 1254 3 of 8

Appl. Sci. 2017, 7, 1254 3 of 8 were used as control groups. Tensile tests, an impact test, and a ﬂexural strength test were conducted were used as control groups. Tensile tests, an impact test, and a flexural strength test were toconducted examine the to examine mechanical the mechanical properties properties of the resultant of the products.resultant products.

Figure 1. Schematic diagram of the manufacturing process. PP: polypropylene; MPP: modified Figure 1. Schematic diagram of the manufacturing process. PP: polypropylene; MPP: modified impact‐resistant polypropylene; TPU: thermoplastic polyurethane. impact-resistant polypropylene; TPU: thermoplastic polyurethane. 2.3. Tests 2.3. Tests 2.3.1. Scanning Electron Microscopy (SEM) 2.3.1. Scanning Electron Microscopy (SEM) SEM analysis (Phenom Pure+, Phenom world, Jing Teng Tech Limited Company, New Taipei City,SEM Taiwan) analysis were (Phenom used to observe Pure+, Phenomthe fractured world, samples Jing Tengcollected Tech from Limited the impact Company, strength New test. Taipei City,Moreover, Taiwan) the were distribution used to observeof TPU in the PP90/TPU10 fractured samples blends and collected MPP90/TPU10 from the blends impact were strength also test. Moreover,observed using the distribution SEM. of TPU in PP90/TPU10 blends and MPP90/TPU10 blends were also observed using SEM. 2.3.2. Differential Scanning Calorimetry (DSC) 2.3.2. DifferentialA differential Scanning scanning Calorimetry calorimeter (Q200, (DSC) TA Instruments, New Castle, DE, USA) was used to evaluateA differential the influence scanning of TPU calorimeter on the crystallization (Q200, TA Instruments,temperature, Newcrystallization Castle, DE, enthalpy, USA) wasmelting used to evaluatetemperature, the influence and melting of TPUenthalpy on the of MPP90/TPU10 crystallization and temperature, PP90/TPU10. crystallization enthalpy, melting temperature, and melting enthalpy of MPP90/TPU10 and PP90/TPU10. 2.3.3. X‐ray Diffraction (XRD) 2.3.3. X-rayAn X‐ Diffractionray diffractometer (XRD) (MXP3, Mac Science, Yokohama, Japan) was used to measure the crystallineAn X-ray structure diffractometer of the samples. (MXP3, The Mac diffraction Science, angle Yokohama, was between Japan) 10 and was 30°, used and tothe measure test rate the was 2 °/min. crystalline structure of the samples. The diffraction angle was between 10 and 30◦, and the test rate was 2◦/min. 2.3.4. Mechanical Properties 2.3.4. MechanicalTensile tests Properties were conducted as specified by ASTM D638, while the flexural strength test was conducted as specified by ASTM D790‐10. An Instron 5566 (Instron, Canton, MA, USA) was used for Tensile tests were conducted as specified by ASTM D638, while the flexural strength test was the tensile and flexural tests. A notched Izod impact strength test was performed to measure the conducted as specified by ASTM D790-10. An Instron 5566 (Instron, Canton, MA, USA) was used impact energy and impact strength of samples using an Izod impact strength tester (CPI, ATLAS, forMount the tensile Prospect, and Chicago, flexural IL, tests. USA) A notchedas specified Izod by impact ASTM D256 strength‐10. For test each was test, performed 10 samples to measure for each the impactspecification energy were and tested impact in strengthorder to determine of samples the using mean anin a Izod given impact condition. strength tester (CPI, ATLAS, Mount Prospect, Chicago, IL, USA) as specified by ASTM D256-10. For each test, 10 samples for each specification3. Results and were Discussion tested in order to determine the mean in a given condition. Appl. Sci. 2017, 7, 1254 4 of 8

3. ResultsAppl. Sci. 2017 and, 7, Discussion 1254 4 of 8

3.1.3.1. Morphology Morphology of of PP/TPU PP/TPU and and MPP/TPU MPP/TPU Blends FigureFigure2A 2A shows shows that that PP100 PP100 had had a smooth a smooth fractured fractured surface, surface, and and the the growth growth path path of of cracks cracks was short.was Theshort. majority The majority of cracks of cracks were parallelwere parallel and classiﬁed and classified as typical as typical fragility fragility [10]. PP[10]. is PP a polymer is a composedpolymer ofcomposed mono propylene of mono propylene units, and units, its molecular and its molecular chains are chains regularly are regularly arranged. arranged. Therefore, PPTherefore, exhibits lowerPP exhibits impact lower resistance impact dueresistance to its due regular to its arrangement regular arrangement of polymer of polymer chains. chains. MPP is a MPP is a copolymer with many side chains in its molecular structure, leading to a better impact copolymer with many side chains in its molecular structure, leading to a better impact resistance. resistance. Figure 2B reveals that MPP100 had cracks on the fractured surface and that the cracks Figure2B reveals that MPP100 had cracks on the fractured surface and that the cracks were aligned in were aligned in different directions. Moreover, the fractured surface of MPP100 possessed a different directions. Moreover, the fractured surface of MPP100 possessed a multilayered structure and multilayered structure and rough surface, indicating that MPP100 can effectively absorb externally roughexerted surface, impact indicating energy [10]. that Figure MPP100 2C illustrates can effectively that, for absorb PP90/TPU10, externally TPU exerted particles impact at a dispersive energy [ 10]. Figurephase2C were illustrates evenly that, distributed for PP90/TPU10, in PP at a TPU continuous particles phase. at a dispersive When an impact phase were force evenly was exerted distributed at inPP90/TPU10, PP at a continuous the stress phase. was concentrated When an impact on TPU, force and was the exertedblend started at PP90/TPU10, to deform and the absorbed stress was concentratedimpact energy. on TPU, Figure and 2D the shows blend that, started when to deformMPP90/TPU10 and absorbed is impacted, impact 10 energy. wt% TPU Figure can2D form shows that,tremendous when MPP90/TPU10 micro‐cracks is impacted,or shear bands 10 wt% that TPU are can able form to tremendous dissipate micro-cracksimpact energy, or shearthereby bands thatstrengthening are able to dissipate the toughness impact of energy,MPP90/TPU10. thereby strengthening the toughness of MPP90/TPU10.

Figure 2. Fractured surface of (A) PP100 (1000×), (B) MPP100 (500×), (C) PP90/TPU10 (1500×), and Figure 2. Fractured surface of (A) PP100 (1000×), (B) MPP100 (500×), (C) PP90/TPU10 (1500×), (D) MPP90/TPU10 (1500×). and (D) MPP90/TPU10 (1500×). 3.2. Melting and Crystalline Behaviors 3.2. Melting and Crystalline Behaviors PP is a semi‐crystal polymer, whose melting and crystallization properties depend on its structure,PP is a semi-crystalthe copolymer, polymer, and the whose fillers. melting The melting and crystallization and crystalline properties behaviors depend of all on blends its structure, are theindicated copolymer, in Table and the 1 and fillers. Figure The 3. melting Based andon the crystalline DSC results, behaviors TPU ofexhibited all blends a crystallization are indicated in Tabletemperature1 and Figure of 362.41. Based °C, ona crystallization the DSC results, enthalpy TPU exhibited of 5.82 J/g, a crystallization a melting point temperature of 145.69 °C, of 62.41and a ◦C, a crystallizationmelting enthalpy enthalpy of 8.49 of J/g, 5.82 and J/g, all aof melting these values, point compared of 145.69 ◦withC, and other a melting groups, enthalpy are much of lower. 8.49 J/g, andFigure all of 3A these shows values, that comparedPP100 and with MPP100 other possess groups, similar are much melting lower. points, Figure which3A showswere 165.29 that PP100 °C and and MPP100165.64 possess°C, respectively. similar melting Moreover, points, the melting which werepoint 165.29did not◦ Cfluctuate and 165.64 after◦ C,the respectively. addition of 10 Moreover, wt% theTPU, melting indicating point did that not TPU fluctuate did not after affect the the addition crystalline of 10 structure wt% TPU, or indicatingstability of that PP. TPUIn contrast, did not 10 affect thewt% crystalline TPU decreaseed structure the or melting stability enthalpy of PP. In of contrast, PP90/TPU10 10 wt% by 15 TPU J/g. decreaseedThis is ascribed the to melting the presence enthalpy of TPU that was an amorphous polymer. Compared with PP100, PP90/TPU required relatively little of PP90/TPU10 by 15 J/g. This is ascribed to the presence of TPU that was an amorphous polymer. energy to hamper the reaction between molecules, contributing to a greater mobility of the PP Compared with PP100, PP90/TPU required relatively little energy to hamper the reaction between molecular chain. Figure 3B reveals no significant differences in the crystallization temperature or molecules, contributing to a greater mobility of the PP molecular chain. Figure3B reveals no significant the crystallization enthalpy between MPP100 and MPP90/TPU10. MPP is a modified PP polymer differenceswith low in crystallization, the crystallization whereas temperature TPU is oran the amorphous crystallization polymer. enthalpy Their between (MPP90/TPU10) MPP100 and MPP90/TPU10.combination caused MPP is a aslight modified decrease PP polymerin the crystallization with low crystallization, temperature and whereas crystallization TPU is an enthalpy amorphous of MPP90/TPU10. In addition, the combination of PP and amorphous polymer TPU in PP90/TPU10 Appl. Sci. 2017, 7, 1254 5 of 8 polymer. Their (MPP90/TPU10) combination caused a slight decrease in the crystallization temperature Appl. Sci. 2017, 7, 1254 5 of 8 and crystallization enthalpy of MPP90/TPU10. In addition, the combination of PP and amorphous polymerresulted TPU in an in PP90/TPU10increasing crystallization resulted in temperature. an increasing Compared crystallization to PP100, temperature. the crystallization Compared of to PP100,PP90/TPU10 the crystallization took longer. of PP90/TPU10 PP has a polymorphism took longer. PP that has can a polymorphism be divided into that three can be crystalline divided into threestructures: crystalline an α structures:crystal form an αofcrystal the monoclinic form of the system, monoclinic a β crystal system, form a ofβ thecrystal hexagonal form of system, the hexagonal and system,a γ crystal and aformγ crystal of the formorthorhombic of the orthorhombic system [11]. Under system common [11]. Under processing common conditions, processing isotactic conditions, PP isotacticoften shows PP often an α showscrystalline an α form.crystalline Figure form. 3C shows Figure that,3C in shows the XRD that, test, in thewhen XRD 2θ test,was 14.1°, when 16.8°, 2 θ was 14.118.5°,◦, 16.8 21.3°,◦, 18.5 and◦, 21.3 21.8°,◦, and the 21.8 corresponding◦, the corresponding Bragg Braggdiffraction diffraction characteristic characteristic peaks peaks of PP of PPwere were accompaniedaccompanied by by crystal crystal plane plane diffraction diffraction of (110), (040), (040), (130), (130), (111), (111), and and (131) (131) [1,12–14]. [1,12–14 The]. The results results illustratedillustrated that, that, for for PP90/TPU10 PP90/TPU10 andand MPP/TPU,MPP/TPU, the the diffraction diffraction peak peak remained remained the the same, same, indicating indicating thatthat adding adding TPU TPU did did not not create create a a new new crystalline crystalline structure [15,16]. [15,16]. Moreover, Moreover, both both PP/TPU PP/TPU at (110) at (110) and MPP90/TPU10 at (040) had higher strengths. There were no significant differences in other and MPP90/TPU10 at (040) had higher strengths. There were no significant differences in other peak peak values, suggesting that TPU did not function as a nucleating agent in the PP or MPP matrix values, suggesting that TPU did not function as a nucleating agent in the PP or MPP matrix and thus and thus did not cause any significant difference in the crystalline phases of PP or MPP [11]. did not cause any significant difference in the crystalline phases of PP or MPP [11]. Table 1. Melting and crystalline behavior of PP/TPU blends and MPP/TPU blends. PP: Table 1. polypropylene;Melting and MPP: crystalline modified behavior impact‐resistant of PP/TPU polypropylene; blends and TPU: MPP/TPU thermoplastic blends. polyurethane. PP: polypropylene; MPP: modified impact-resistant polypropylene; TPU: thermoplastic polyurethane.

Crystallization Crystallization Melting Melting Crystallization Crystallization Melting Melting SampleSample Codes Codes Temperature◦ Enthalpy Temperature◦ Enthalpy Temperature(°C) ( C) Enthalpy(J/g) (J/g) Temperature(°C) ( C) Enthalpy(J/g) (J/g) TPU100TPU100 62.4162.41 5.825.82 145.69145.69 8.49 8.49 PP100PP100 115.24115.24 106.20106.20 165.29165.29 115.40 115.40 PP90/TPU10PP90/TPU10 121.62121.62 96.2396.23 165.13165.13 100.10 100.10 MPP100MPP100 129.56129.56 83.6183.61 165.77165.77 88.27 88.27 MPP90/TPU10MPP90/TPU10 130.20130.20 83.7183.71 165.64165.64 87.22 87.22

Figure 3. Melting and crystalline behavior of PP/TPU and MPP/TPU blends: (A) heating curve, (B) Figure 3. Melting and crystalline behavior of PP/TPU and MPP/TPU blends: (A) heating curve, cooling curve, and (C) X‐ray Diffraction (XRD) pattern. (B) cooling curve, and (C) X-ray Diffraction (XRD) pattern. 3.3. Mechanical Behaviors 3.3. Mechanical Behaviors Figure 4A,B show the tensile behavior and flexural strength of the experimental group and the controlFigure group.4A,B show PP100 the and tensile PP90/TPU10 behavior andhad ﬂexural a greater strength tensile of thestrength experimental than MPP100 group andand the controlMPP90/TPU10. group. PP100 PP100 and was PP90/TPU10 composed had of ahighly greater aligned tensile molecular strength than chains MPP100 and thus and MPP90/TPU10.had greater PP100crystallinity, was composed and its tensile of highly strength aligned reached molecular 37.12 MPa. chains In and addition, thus hadPP90/TPU10 greater crystallinity,possessed higher and its elongation than PP100, which was ascribed to TPU. TPU is a thermoplastic elastomer that provides Appl. Sci. 2017, 7, 1254 6 of 8 tensile strength reached 37.12 MPa. In addition, PP90/TPU10 possessed higher elongation than Appl. Sci. 2017, 7, 1254 6 of 8 PP100, which was ascribed to TPU. TPU is a thermoplastic elastomer that provides PP90/TPU10 withPP90/TPU10 greater elongation. with greater To elongation. sum up, To the sum elongation up, the elongation at break could at break be could ranked be from ranked highest from to lowesthighest as to MPP90/TPU10, lowest as MPP90/TPU10, MPP100, MPP100, and then and PP90/TPU10. then PP90/TPU10. MPP MPP with with a great a great toughness toughness and thermoplasticand thermoplastic elastomer elastomer TPU TPU had ahad synergistic a synergistic effect, effect, demonstrated demonstrated by by the the highest highest elongationelongation at breakat break of MPP90/TPU10. of MPP90/TPU10.

FigureFigure 4. Tensile4. Tensile and ﬂexuraland flexural behavior behavior of PP/TPU of PP/TPU blends blends and MPP/TPU and MPP/TPU blends: blends: (A) tensile (A) propertiestensile andproperties (B) ﬂexural and properties. (B) flexural properties.

Table 2 shows that MPP100 and MPP90/TPU10 exhibited higher tensile strength, Young’s modulus,Table2 showsand flexural that MPP100 strength and than MPP90/TPU10 PP100 and PP90/TPU10. exhibited higherMoreover, tensile PP100 strength, outperformed Young’s modulus,PP90/TPU10 and because flexural PP strength at the continuous than PP100 phase and had PP90/TPU10. a lower bonding Moreover, level due PP100 to the outperformedpresence of PP90/TPU10TPU, which because compromised PP at the the continuous mechanical phase properties. had a lower On bonding the other level hand, due toMPP100 the presence and of TPU,MPP90/TPU10 which compromised could bear the more mechanical impact energy properties. and possessed On the other a higher hand, impact MPP100 strength and MPP90/TPU10 than PP100 couldand bear PP90/TPU10. more impact Due energyto modification, and possessed MPP exhibited a higher impacta greater strength toughness than than PP100 PP, and PP90/TPU10.thus could Duewithstand to modification, greater impact MPP exhibitedenergy and a greatershowed toughnesshigher impact than strength. PP, and In thus particular, could withstand MPP90/TPU10 greater impactcould energy absorb and an showedimpact energy higher of impact 43.3 J, strength. and MPP100 In particular, had an impact MPP90/TPU10 strength of could 8.48 absorb kJ/m2. an impactNevertheless, energy of compared 43.3 J, and with MPP100 MPP100, had MPP90/TPU10 an impact strength still had of 8.48a lower kJ/m impact2. Nevertheless, strength. This compared was withascribed MPP100, to modified MPP90/TPU10 impact‐resistance still had apolypropylene lower impact (i.e., strength. MPP) that This contained was ascribed more to ethylene modified impact-resistancegroups that was polypropylene incompatible with (i.e., TPU. MPP) The that differences contained in more polarity ethylene between groups MPP that and was TPU incompatible is high, and the presence of PP may break the hydrogen bond of TPU, resulting in lower mechanical with TPU. The differences in polarity between MPP and TPU is high, and the presence of PP may break properties [10]. the hydrogen bond of TPU, resulting in lower mechanical properties [10].

Table 2. Mechanical properties of PP/TPU and MPP/TPU blends. Table 2. Mechanical properties of PP/TPU and MPP/TPU blends. Tensile Strength Young’s Modulus Energy Flexural Strength Impact Strength Sample Codes Tensile(MPa) Strength Young’s(MPa) Modulus (J) Flexural(MPa) Strength Impact(kJ/m Strength2) Sample Codes Energy (J) MPP100 29.19(MPa) ± 1.93 974(MPa) ± 40.32 32.82 ± 8.34 49.06(MPa) ± 1.92 8.48(kJ/m ± 0.552) MPP90/TPU10MPP100 29.1929.79± ±1.93 1.55 974977± ±40.32 26.67 43.33 32.82 ± 10.248.34 49.88 49.06 ± ±0.781.92 4.93 8.48 ± 0.25± 0.55 MPP90/TPU10PP100 29.7937.12± ±1.55 0.55 1046.79 977 ± 26.67 ± 37.47 43.3321.01± ± 10.242.68 58.60 49.88 ± ±1.390.78 2.76 4.93 ± 0.21± 0.25 PP90/TPU10PP100 37.1232.36± ±0.55 0.86 1046.791016.80± 37.47± 9.89 21.0123.15 ±± 2.562.68 57.93 58.60 ± ±0.341.39 3.49 2.76 ± 0.88± 0.21 PP90/TPU10 32.36 ± 0.86 1016.80 ± 9.89 23.15 ± 2.56 57.93 ± 0.34 3.49 ± 0.88 4. Conclusions 4. ConclusionsIn this study, TPU was added to PP or MPP to form blends, and the blending morphology, crystallizationIn this study, behavior, TPU was melting added behavior, to PP or and MPP mechanical to form blends,properties and of the blends blending were examined. morphology, crystallizationThe SEM images behavior, showed melting that MPP100 behavior, and MPP90/TPU10 and mechanical absorbed properties higher of imapct blends energy. were The examined. DSC Theand SEM XRD images results showed revealed that that MPP100 the addition and MPP90/TPU10of TPU did not affect absorbed the strucutre higher imapct of PP/TPU energy. blends The but DSC andinfluenced XRD results its melting revealed and that crystallization the addition ofenthalpy. TPU did The not mechanical affect the strucutre property oftest PP/TPU results blendsshowed but that, among the blends, PP100 and PP90/TPU10 had greater tensile strength, a greater Young’s influenced its melting and crystallization enthalpy. The mechanical property test results showed that, modulus, and a greater flexural strength, while MPP100 and MPP90/TPU10 absorbed greater among the blends, PP100 and PP90/TPU10 had greater tensile strength, a greater Young’s modulus, impact energy and had higher impact strength. It was surmised that MPP at the continuous phase and a greater flexural strength, while MPP100 and MPP90/TPU10 absorbed greater impact energy may harm the hydrogen bond of TPU at the dispersive phase, which jeopardized its intrinsic high Appl. Sci. 2017, 7, 1254 7 of 8 and had higher impact strength. It was surmised that MPP at the continuous phase may harm the hydrogen bond of TPU at the dispersive phase, which jeopardized its intrinsic high toughness. This study proposes a flexibly feasible design of polymer blends, which can be freely adjusted to suit the requirements of products and satisfy the user end.

Acknowledgments: The authors would like to thank Ministry of Science and Technology of Taiwan, for supporting this research under Contract MOST 106-2622-E-035 -013 -CC3. Author Contributions: In this study, the concepts and designs for the experiment, all required materials, as well as processing and assessment instrument were provided by Jia-Horng Lin. Data were analyzed, and the experimental results examined, by Ching-Wen Lou. The experiment was conducted, and the text composed, by Ting An Lin. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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