Synthesis of Organic-Inorganic Hybrid Aluminum Hypophosphite Microspheres Flame Retardant and Its Flame Retardant Research on Thermoplastic Polyurethane

Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of micro-nanospheres with cyclic cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS). A new organic-inorganic poly(phosphonitrile)-modified aluminum hypophosphite microspheres(PZS-AHP) were synthesized by encapsulation and applied to flame retardant thermoplastic polyurethane(TPU). The microstructure and chemical composition of the PZS-AHP microsphere were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray spectroscopy. The thermal stability of PZS-AHP microsphere was explored with thermogravimetric analysis. Thermogravimetric data indicate that the PZS-AHP microspheres have excellent thermal stability. The thermal and flame-retarding properties of the TPU composites were evaluated by thermogravimetric(TG), limited oxygen index tests(LOI), and cone calorimeter test(CCT). The TPU composite achieved vertical burning(UL-94) V-0 grade and LOI value reached 29.2% when 10 wt% PZS-AHP was incorporated. Compared with those of pure TPU, the peak heat release rate(pHRR) and total heat release(THR) of TPU/10%PZS-AHP decreased by 82.2% and 42.5%, respectively. The results of CCT indicated that PZS-AHP microsphere could improve the flame retardancy of TPU composites.

Improving the Compatibility of Biodegradable Poly (Lactic Acid) Toughening with Thermoplastic Polyurethane (TPU) and Compatibilized Meltblown Nonwoven

Poly (Lactic Acid) (PLA) is a biodegradable polymer which originates from natural resources such as corn and starch, offering excellent strength, biodegradability, nevertheless its inherent brittleness and low impact resistance properties have limited its application. On the other hand, Thermoplastic Polyurethane (TPU) has high toughness, durability and flexibility, which is one of the most potential alternatives for enhancing the flexibility and mechanical strength of Poly (Lactic Acid) (PLA) by blending it with a compatibilizer. With the aim to improve the mechanical and thermal properties of Poly (Lactic Acid) (PLA) meltblown nonwovens, The Thermoplastic Polyurethane (TPU) was melt blended with Poly (Lactic Acid) (PLA) at the different corresponding proportions for toughening the Poly (Lactic Acid) and the corresponding PLA/TPU MBs (meltblown nonwovens) were also manufactured. Joncryl ADR 4400 is mixed into the PLA matrix during processing. It was found that Joncryl had a much higher chain extension that substantially increased the molecular weight of the PLA matrix. SEM study revealed that Joncryl ADR 4400 is a good compatibilizer. Moreover, in this study, the crystallization, thermal and rheological behaviors of the corresponding PLA and TPU blends were also investigated. PLA/TPU MBs were also characterized by morphology and mechanical properties. The rheological property of the PLA/TPU meltblown nonwoven revealed that the viscosity is increasing as the amount of TPU is increasing in the blend, PLA/TPU meltblown nonwovens exhibited excellent mechanical properties;they are soft, elastic, and have certain tensile strength. New materials have potential applications in the medical and agricultural fields. Joncryl ADR 4400 compatibilized blends showed higher strength than simple PLA/TPU blends at the same PLA/TPU ratio.

Effect of microwave treatment on tensile properties of sugar palm fibre reinforced thermoplastic polyurethane composites

The effect of microwave treatment on the tensile properties of treated sugar palm fibre with 6% NaOH reinforced thermoplastic polyurethane composites was investigated. Firstly, the sugar palm fibres were treated by 6% alkali solution. Then, microwave treatment was used to treat the alkali treated sugar palm fibres. Three types of temperatures(i.e. 70, 80 and 90℃) were applied in microwave treatment. The extruder and hot press machines were used to mixing the sugar palm fibres and polyurethane resin, and fabricate the composites. Tensile properties(i.e. tensile strength, tensile modulus and elongation at break) were studied by following the ASTM D-638 standard. The highest tensile strength was recorded 18.42 MPa with microwave temperature at 70℃ and 6% alkali pre-treatment. Therefore, the temperature 70℃ of microwave treatment may consider the best degree cent grate.

Physical and damping properties of kenaf fibre filled natural rubber/thermoplastic polyurethane composites

The paper presents the investigation of the effect of alkaline treatment of sodium hydroxide(NaOH) on physical and dynamic mechanical analysis(DMA) viscoelastic properties of kenaf fibre filled natural rubber(NR)/thermoplastic polyurethane(TPU) composites.The treated kenaf fiber,NR and TPU were weighed and proportioned according to the required compositions and were blended using hot mixed Brabender machine.The polymer composites were then fabricated using the hot press to form a sample board.The sample was cut and prepared and water absorption,density,thickness swelling and DMA tests were performed.As far as physical properties are concerned,composites with the highest NR amount of shows the best results,which indicates good fiber bonding adhesion.The polymer composites with the highest amount of TPU shows the highest damping properties at high temperature.

Effect of Accelerated Xenon Lamp Aging on the Mechanical Properties and Structure of Thermoplastic Polyurethane for Stratospheric Airship Envelope

This study aimed to investigate the effect of artificial weathering test on the photoaging behavior of TPU films. Changes in mechanical properties, morphology and chemical structures are studied by tensile test, scanning electron microscopy, atomic force microscopy, Fourier-transformed infrared, and X-ray photoelectron spectroscopy. The results show that the photoaging negatively affects the initial modulus and stress at break values of TPU films. The surface of the specimen that is exposed to irradiation becomes rough, and some visible micro-defects such as blisters and voids can be detected. The morphology of the fracture surfaces illustrates that irradiation reduces the plasticity but increases the brittleness of the TPU films. The chemical structure analyses of the accelerated aged films prove that chemical structural changes in TPU films occur. The irradiation may break the long molecular chains on the surface of the specimens and form the lowmolecular weight oxygen-containing groups. The number of chain scissions increases with the increase in exposure time.

Synthesis and Properties of Non-isocyanate Crystallizable Aliphatic Thermoplastic Polyurethanes

A simple non-isocyanate route synthesizing thermoplastic polyurethanes（TPUs） with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited Mn ranging from 12 500 to 26 400 g/mol, Mw from 16 700 to 56 400 g/mol, Tm up to 151.4 °C, and initial decomposition temperature over 241.8 °C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route.

Mechanical and Thermal Properties of Sugar Palm Fiber Reinforced Thermoplastic Polyurethane Composites:Effect of Silane Treatment and Fiber Loading

The aim of the present study was to develop sugar palm fiber(SPF)reinforced thermoplastic polyurethane(TPU)composites and to investigate the effects of fiber surface modification by 2%silane treatment and fiber loading(0,10,20,30,40 and 50 wt%)on the mechanical and thermal properties of the obtained composites.Surface treatment was employed to improve the fiber-matrix interface,which was expected to boost the mechanical strength of the composites,in terms of tensile,flexural and impact properties.Thermal properties were also investigated by thermal gravimetric analysis(TGA)and dynamic mechanical analysis(DMA)to assess the thermal stability of the developed composites.Furthermore,scanning electron microscopy(SEM)was used to study the tensile fracture samples of composites with a view towards evaluating the effects of fiber surface treatments on the fiber/matrix interfacial bonding.The findings of this study reveal that the silane treatment has determined good bonding and linkage of the cellulose fiber to the TPU matrix,hence contributing to enhanced mechanical and thermal properties of the composites.The composite formulation with 40 wt%sugar palm fiber loading showed optimum values such as 17.22 MPa for tensile,13.96 MPa for flexural,and 15.47 kJ/m^2 for impact strength.Moreover,the formulations with higher fiber content exhibited satisfactory values of storage modulus and thermal degradation,while their good interfacial adhesion was evidenced by SEM images.

HYDROGEN BOND EFFECT IN THERMOPLASTIC POLYURETHANE ELASTOMERS

Hydrogen bond effects in thermoplastic polyurethane elastomers (TPU) with different chain extender structures and hard segment contents have been studied quantitatively by dynamic mechanical analysis. It has been found that the hydrogen bond effects in TPU decrease with the increase of temperature. The temperature dependence of hydrogen bonding in TPU’s can be described by the Arrhenius equation, and the activation energy of hydrogen bonding as well as the physical cross-link density have been calculated.

Hydrogen Bonding in Thermoplastic Polyurethane Elastomers:IR Thermal Analysis

The hydrogen bond percentage and its temperature dependence of the three TPU samples synthesized from polytetrahydrofuran, 4,4'-diphenylmethane diisocyanate, N -methyl diethanol amine or 1,4-butane diol were studied by means of IR thermal analysis. The enthalpy and the entropy of the hydrogen bond dissociation were determined by the Van't Hoff plot.

Fabrication and Characterization of Poly(Styrene-Butadiene-Styrene)/Thermoplastic Polyurethane Blends

This investigation presents thermoplastic elastomers (TPEs) based on poly (styrene-butadiene-styrene) (SBS) and thermoplastic polyurethane (TPU) materials were prepared with varying compositions. A series of works were conducted on the relationships between rheological, optical properties, morphology, mechanical properties, abrasion resistance and thermostability given. The results showed that the shear viscosity of SBS not obvious effect with TPU content. The optical properties of the SBS/TPU blend that its uniform transparency. The morphology characteristics indicating the phase diversion and the variation in the size of the SBS domains from large to small as the TPU contents increased, with heterogeneous domain dispersions. Additionally, the mechanical properties, abrasion resistance and thermal resistance are improved as the amount of added TPU is increased, suggesting that the blending of SBS with TPU is consistent with the compound rule.

Design and Multicriteria Optimization of a Two-Stage Reactive Extrusion Process for the Synthesis of Thermoplastic Polyurethanes

This paper presents the implementation of two multicriteria optimization methods based on different approaches, namely, Rough Set Method (RSM) and Net Flow Method (NFM), to the manufacture by reactive extrusion of linear thermoplastic polyurethanes (TPUs), appropriate for medical applications. A preliminary study allowed determining the process operating conditions for which the polymerization time and the average residence time of the reactants in the extruder are of the same order of magnitude. Prior to the optimization, a neural network model able to predict with acceptable accuracy the effect of the operating conditions on the output process variables, was constructed and validated. This model was then used to determine, using Pareto’s concept, a set of non-dominated solutions constituting Pareto’s domain. These solutions were then ranked according to the preferences of a decision maker using NFM and RSM. This allowed providing the 10% highest ranked solutions of Pareto’s domain and proposing a set of optimal operating conditions for the production, with the lowest energy consumption, of TPUs with targeted properties and high purity. Experimental validation runs carried out under similar operating conditions gave rise to criteria values confirming the su- perior performance of NFM, without rejecting, at the same time, the values obtained using RSM.

Mechanical, Thermal and Morphology Properties of Thermoplastic Polyurethane Copolymers Incorporating α,ω-Dihydroxy-[poly(propyleneoxide)-poly (dimethylsiloxane)-poly(propyleneoxide)] of Varying Poly(propyleneoxide) Molecular Weight

Novel segmented thermoplastic polyurethane (TPU) copolymers were synthesized using two-step solventless bulk polymerization. 4,4’-methylenediphenyl diisocyanate (MDI) and 1,4-Butanediol (BDO) were used to form hard segment of TPU and α,ω-dihydroxy-[poly(propyleneoxide)-poly (dimethylsiloxane)-poly(propyleneoxide)] (α,ω-dihydroxy-(PPO-PDMS-PPO)) was used to form soft segment of TPU, where the molar ratio of the –N=C=O/OH was 1.02 and the hard segment weight percentage was 30%. A series of TPUs were characterized by fourier transform infrared spectroscopy (FT-IR). The investigation of triblock oligomer’s PPO molecular weight impact on the derived TPU’s mechanical properties, thermal performance, surface water repellency and morphology performance was carried by Instron material tester, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), water contact angles (WCA), scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDX) and wide angle X-ray diffraction (WAXD), respectively. FT-IR confirmed α,ω-dihydroxy-(PPO-PDMS-PPO) well cooperating into urethane structure and analyzed hydrogen bonding between N-H group with hard segment C=O group and N-H group with soft segment C-O-C group. DSC and WAXD results showed α,ω-dihydroxy-(PPO-PDMS-PPO) segments crystallization. SEM-EDX results showed that the presence of a spherulitic morphology, which arose from the crystallization of the PPO segments. The thermal properties measured by TGA and DSC were slightly affected by molecular weight of PPO and microphase separation. The weight loss of TPUs started between 294°C and 300°C, and Tg was in the range of -70°C to -107°C. TPU copolymers’ surface hydrophobicity property was excellent with WCA range of 95°?to 112°. TPU-3 with 1000 molecular weight PPO has the optimized mechanical properties with tensile strength 16.4 MPa and the modulus at 100% elongation 6.2 MPa and elongation 398%.

CPE增容TPU/PVC共混弹性体及相形态

为提高热塑性聚氨酯弹性体(TPU)与聚氯乙烯(PVC)的相容性,以氯化聚乙烯(CPE)为增容剂,经双螺杆挤出机熔融共混制备TPU/PVC共混型热塑性弹性体,测试了不同CPE用量的共混弹性体的拉伸强度、断裂伸长率和硬度等力学性能,以及动态流变性能、动态力学性能和热稳定性。通过扫描电子显微镜(SEM)对共混弹性体的相态结构进行研究。结果表明,当TPU/PVC质量比为70/30时,共混弹性体综合力学性能最佳,拉伸强度为19.92 MPa,断裂伸长率为972%。随着CPE用量的增加,TPU/PVC共混弹性体的拉伸强度、断裂伸长率、硬度等均先增大后减小;CPE用量为6份时,TPU/PVC共混弹性体拉伸强度达到最大,为23.73 MPa,相较未加CPE时提高19.1%。加入CPE的共混弹性体复数黏度和储能模量均呈下降趋势。此外,CPE的加入还能有效提升弹性体高温热稳定性,TPU和PVC两种组分的损耗因子峰内移靠近,共混弹性体液氮脆断面的SEM照片显示PVC相筹明显变小且更为均匀,以上说明CPE对共混弹性体的增塑、增容作用明显,且CPE用量为6份时增容效果最佳。

聚乳酸聚氨酯嵌段预聚体增韧PLA/TPU共混物

合成聚乳酸聚氨酯嵌段共聚物预聚体(PLA-b-PUP),以其作为聚乳酸(PLA)和热塑性聚氨酯(TPU)的活性相容剂,通过原位反应增容制备PLA/TPU/PLA-b-PUP超韧共混物.通过拉伸试验、冲击试验、SEM、FTIR、DSC和TGA研究共混物的力学性能、热性能和增韧机理.结果表明,PLA-b-PUP中的异氰酸酯基团与PLA和TPU上的活性基团发生反应,显著改善了PLA/TPU共混物两相界面的相容性.随着PLA-b-PUP的加入量增加,共混物中PLA的玻璃化转变温度和相对结晶度逐渐降低,当PLA-b-PUP的质量分数为PLA/TPU共混物的4%时,共混材料的断裂伸长率和缺口冲击强度分别达到无相容剂时的8.12和2.73倍,表现出良好的增容增韧效果.添加PLA-b-PUP后,共混物的初始分解温度有所降低,但最快分解温度有所提高.

中空玻璃微球/TPU复合泡沫的制备及微孔结构的研究

目的探讨GB含量变化对中空玻璃微球/TPU复合材料相变行为、流变性能及热力学性能的影响,并研究微米尺寸填料GB对泡沫微孔形态、尺寸分布的影响。方法以中空玻璃微球和热塑性聚氨酯为原料,采用微孔注塑成型(MIM)发泡方式,制备GB/TPU复合泡沫材料。结果通过向TPU中引入微米玻璃球相改善发泡材料的微孔结构,在TPU中加入有机改性的GB,GB作为成核剂能显著提高TPU发泡材料的微孔结构。当GB质量分数为0.5%时,TPU熔体黏度得到提高,发泡性能得到改善,成功制备出具有复孔结构的GB/TPU复合泡沫。GB/TPU复合泡沫的密度被降低至0.51 g/cm^(3)。由于微米尺寸填料GB的平均直径为18μm,与TPU熔体形成较大的相界面,因此引起泡孔尺寸较大且泡孔开孔率较高的现象。结论差示扫描量热仪(DSC)测试结果表明,在冷却阶段及第二次加热熔融阶段,GB对TPU软段相和硬段相的相变行为没有明显的影响。但是在DSC第一次加热熔融阶段,GB引起了TPU熔融峰向低温区移动。旋转流变仪测试分析结果表明,在高剪切频率下,GB/TPU复合材料的复合黏度和储能模量明显高于TPU纯料的,且TPUGB0.5(含质量分数为0.5%的GB)的复合黏度和储能模量最大。TGA结果显示,热稳定性提高,利用扫描电子显微镜(SEM)观察复合材料泡沫材料泡孔结构可知,泡孔分布和尺寸均匀性显著提高。

超临界CO_(2)制备TPU/SiO_(2)复合泡沫及其性能研究

采用热塑性聚氨酯弹性体(TPU)作为基体,纳米二氧化硅(SiO_(2))充当填料,超临界二氧化碳(scCO_(2))为发泡剂,通过简单的物理共混的方式以及scCO_(2)发泡设备制备了TPU/SiO_(2)复合发泡材料;探究了不同SiO_(2)含量对复合发泡材料的影响.结果表明,纳米SiO_(2)粒子在TPU基体中有良好的分散性,所制备的TPU/SiO_(2)复合发泡材料混合均匀;纳米SiO_(2)粒子的添加调控了复合材料的发泡行为,使其泡孔尺寸稳定、分布范围从60~180μm下降至20~40μm.SiO_(2)粒子有效提高了TPU基体的结晶性,从而使得回弹从40上升至42,硬度从45.3 Shore C上升至54.38 Shore C;抗张强度从1.18 MPa上升至4.19 MPa,断裂伸长率从237.25%上升至460.03%.

Chain Extender-induced Hydrogen Bonding Organization Determines the Morphology and Properties of Thermoplastic Polycarbonate Polyurethane

Thermoplastic polycarbonate polyurethanes(PCUs) are multiblock copolymers that have been applied for medical devices for long time. Aliphatic diols are common chain extenders(CE) involved in the composition of the hard segments of PCU. However, limited knowledge was discovered about how the chemical structure of CE affects the hydrogen bonding organization within PCUs and their mechanical properties.To investigate this problem, a group of PCUs were synthesized respectively by extending the polymer chain with 1,4-butanediol(BDO),aminoethanol(MEA), ethanediol(EO) as three kinds of chain extenders. Tiny differences in the CE chemical structure results in remarkable variations in phase separation, condensed morphologies, thermal and mechanical properties, which are characterized by Fourier transform infrared spectrometer, atomic force microscopy, small-angle X-ray scattering, differential scanning calorimetry, and tensile tests. The microstructural evolution during unilateral deformation and the different mechanism induced by the different CEs was probed and unveil by in situ wide-and small-angle X-ray diffraction. Symmetry of CE can improve the organization of the hydrogen bonding. The coherence strength of the urethane/urea group also plays a key role by comparing the two PCUs with ethanediol and aminoethanol.

PVC/TPU共混材料静动态力学性能及本构模型研究

利用万能材料试验机和高速拉伸试验机对2种成型方式和6种共混比的聚氯乙烯/热塑性聚氨酯(PVC/TPU)共混材料开展静动态拉伸力学性能测试,并基于断裂伸长率和邵氏硬度进行成型方式和共混比优选。进一步获取了共混材料在较宽应变率范围(0.001~700 s-1)的应力⁃应变数据,并进行了拉伸断面的微观表征。结果表明,模压成型材料断裂伸长率更高,共混比为90/10时材料具有最高的断裂伸长率,邵氏硬度符合试验假人软组织材料的硬度范围(邵尔40~70 A)。共混比为90/10(PVC/TPU)材料在静动态载荷下均具有显著的应变率效应。选取朱⁃王⁃唐(ZWT)方程和Sherwood⁃Frost方程构建了材料的本构模型,对比发现Sherwood⁃Frost方程拟合效果更好。形貌分析发现,静动态加载下,材料均为典型的脆性断裂,未出现明显的相分离现象。随着应变率的增加,断面逐渐变粗糙,并产生空穴及微小裂纹。

环氧大豆油反应增容对PLA/TPU共混物性能的影响

以热塑性聚氨酯(TPU)为增韧剂、环氧大豆油(ESO)为反应型相容剂,采用熔融共混制备了PLA/TPU/ESO复合材料,研究了ESO的含量对复合材料性能的影响。利用傅里叶红外光谱分析(FTIR)、力学性能测试、差示扫描量热仪(DSC)、热重分析(TGA)、动态力学性能分析(DMTA)、扫描电子显微镜(SEM)进行测试,结果表明,加入ESO后,PLA/TPU共混物的力学性能显著提升,其中,84PLA/10TPU/6ESO复合材料的综合性能最佳,与纯PLA相比,其断裂伸长率和冲击强度分别提升了32倍和8倍,拉伸强度下降了20%,但是,韧性较高,这是由于,ESO与PLA/TPU发生反应,形成PLA-g-TPU共聚物,充当PLA和TPU界面之间的桥梁,提高了PLA与TPU的相容性。