Influence on the Microphase Separation Structure of PU by Low-content CNT Fillers
Influence on the Microphase Separation Structure of PU by Low-content CNT Fillers
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DOI：
10.12783/dtmse/mmme2016/10139
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发表时间：
2017-05
期刊：
影响因子：
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通讯作者：
Lei Cai;Jun Dong;Qun Yang;Zheng-wei Dai
中科院分区：
文献类型：
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作者：
Lei Cai;Jun Dong;Qun Yang;Zheng-wei Dai
微相分离是聚氨酯性能的决定性因素。采用溶液共混法制备了聚氨酯/碳纳米管共混物，研究了碳纳米管对聚氨酯微相分离行为的影响。结果表明，碳纳米管在聚氨酯/碳纳米管共混体系中起到了成核剂的作用。即使仅存在非常少量的碳纳米管，聚氨酯相的平均直径也得到改善。聚氨酯（PU）作为一种著名的热塑性弹性体材料，广泛应用于建筑材料、服装、生物医用材料等领域。近年来，碳纳米管（CNT）被频繁应用于改善PU的力学性能和热稳定性[1-9]。这些改进主要是由于聚氨酯微结构的改变。探讨了碳纳米管对聚氨酯微相分离结构的影响。实验PU的类型是Bayer 985 U。CNT的类型为TNIM 4。它是一种多壁碳纳米管，购自成都有机化工有限公司，N，N-二甲基甲酰胺（DMF）购自上海化学试剂有限公司，为了制备PU/CNT共混物，首先用DMF制备PU溶液。然后将一定量的CNT加入到溶液中，并将溶液以100 RPM的速度搅拌24小时。为了制备膜，将一定量的PU/CNT共混物溶液倾倒在干燥清洁的玻璃板（尺寸为10 × 10 cm 2）上。用可调节的制膜机（上海乐奥测试仪器有限公司，Ltd.）。然后将膜在真空烘箱中在80 ° C的温度下干燥24小时。之后，将膜从玻璃板上剥离，并用相差显微镜（AE 2000，Shanghai Yiyuan Optical Instrument Co.，Ltd.）。结果与讨论首先通过聚氨酯溶液的粘度研究了聚氨酯与碳纳米管的相互作用。结果如图1所示。从图1中我们可以看出，非常少量的CNT可以引起溶液粘度的显著增加。这是由于聚氨酯分子链与碳纳米管结构之间的缠结造成的。图2显示了具有各种CNT含量的PU/CNT共混物的微相分离结构。PU微结构的形态是指相的形状、大小和组成，相边界层的宽度和相邻两相的分子缠结程度，与PU材料的性能密切相关。从图1中可以观察到双连续相分离结构。这种结构是由PU分子链的刚性段和柔性段组成的。没有CNT的样品的相尺寸（图1-A）小，
Microphase separation are the decisive factor for the performance of polyurethane. The blends of polyurethane/carbon nanotubes were prepared by the method of solution blending, and the influence of carbon nanotubes on the microphase separation behaviors of polyurethane was studied. The results show that carbon nanotubes play as the nucleating agent in the blends of polyurethane/ carbon nanotubes. The average diameter of the polyurethane phase was improved even only a very small amount of carbon nanotubes were present. Introduction As a well-known thermoplastic elastomer material, polyurethane (PU) is widely used in the fields of building material, garments, biomedical materials, etc. Recent years, carbon nanotubes (CNT) has been frequently applied to improve the mechanical properties and thermal stability of PU[1-9]. These improvements are greatly caused by the modification of the micro structure of PU. In this paper, the influence of CNT on the micro phase separation structure of PU was discussed. Experimental The type of PU is Bayer 985U. The type of CNT is TNIM4. It’s a multi-wall CNT and was purchased from Chengdu Organic Chemical Co., Ltd. N,N-dimethyl formamide (DMF) were purchased from Shanghai Chemical Reagent Co., Ltd. To prepare the PU/CNT blend, PU solution was first prepared with DMF. Then certain amount of CNT was added into the solution and the solution was stirred for 24 h at the speed of 100 RPM. For the preparation of film, certain amount of PU/CNT blend solution was poured on the dry clean glass plate (10 10 cm2 in size). A film with the thickness of 100 μm was prepared with an adjustable film maker (Shanghai Le Ao Test Instrument Co., Ltd.). The film was then dried in the vacuum oven in the temperature of 80 oC for 24 h. After that the film was peeled off from the glass plate, and observed with the phase contrast microscope (AE2000, Shanghai Yiyuan Optical Instrument Co., Ltd.). Results and Discussions The interaction of PU and CNT was first investigate by viscosity of PU solution. The results are displayed in Figure 1. From Figure 1 we can see that very small amount of CNT could cause a significant increase of the solution viscosity. This was caused by the entanglement between PU molecular chains and the structure of CNT. Figure 2 shows the microphase separation structure of PU/CNT blends with various CNT contents. The morphology of PU microstructure refers to the shape, size and composition of the phases, the width of the phase boundary layer and the degree of molecular entanglement of the two neighboring phases, which are closely related to the properties of PU materials. From Figure 1, a bicontinuous phase separation structure can be observed. This structure was formed by the rigid segments and soft segments of PU molecular chains. The phase size of the sample without CNT (Figure 1-A) is small,