Professor: CHANG-NING HUANG Student: CHIH-HAO WANG Date: 2015/12/30

Introduction Polyurethane (PU) is a resilient elastomer that has a wide range of application as coatings, sealants, transdermal patches, and catheters. In this paper, SWNTs modified PU composite ultrathin fibers with various contents of SWTNs have been prepared by use of electrospinning. The highest content of SWNTs in the PU ultrathin fibers is 10 wt%. Morphology, thermal properties, DC and AC conductivity of the obtained composite fibers have been studied and discussed simultaneously.

Materials TPU: Tetrahydrofuran (THF): N-N dimethyl formamide(DHF): Single-walled Carbon nanotubes (SWNTs):

Experimental Termoplastic PU was dissolved in tetrahydrofuran (THF) and N-N dimethyl formamide(DMF) (THF:DMF = 6:4, weight ratio), and the content of the PU in the solution was 10 wt ％. The functionalized SWNTs were added into the PU solution, and the weight ratio of SWNTs-to-PU is set as 0:100 (0 ％ ), 1:100 (1 ％ ), 3:100 (3 ％ ), 5:100 (5 ％ ), and 10:100 (10 ％ ). The mixtures were sonicated in a bath sonicator. Using electrospinning preparation nonwovens was in the range of 80–100 µm.

Results and discussion-SEM Figure 1. SEM images of SWNTs/PU nonwoven fibers with SWNTs loading (A) 0 wt ％, (B) 1 wt ％,(C) 5 wt ％, and (D) 10 wt ％.

Results and discussion-TGA Figure 2. TGA curves of the studied samples with various contents of SWNTs.

Results and discussion- DMA Figure 3. DMA curves of SWNTs/PU ultrathin fibrous nonwovens as a function of SWNTs.

Results and discussion-Conductivity(1) Table 1 The content of SWNTs in the nonwovens and the obtained properties of SWNTs/PU nanofibrous nonwovens.

Results and discussion- Conductivity(2) Figure 4. DC Conductivity of electrospinning nonwovens and casting films versus SWNTs content.

Results and discussion-Conductivity(3) Figure 5. Conductivity of electrospinning nonwovens (a), and casting films (b) versus the frequency.

Results and discussion-Conductivity(4) Figure 6. Comparisons of the AC conductivities at 50 Hz.

Conclusions Electrospinning technique was used to produce SWNTs/PU nonwovens. With the SWNTs loading increasing from 0 to 10 wt ％,the diameter of the ultrathin fibers decreases continuously, and the decomposition temperature, Tg, DC and AC conductivity increase significantly. We expect that the SWNTs/PU nonwovens can be useful for various applications such as electrostatic discharge and electromagnetic shielding.