Functionalized graphene nanoplatelets (f-GNS) were modified with (3-mercaptopropyl)trimethoxysilane (MPTMS) to enhance their compatibility with the polyurethane coating matrix. The results of Fourier transform infrared spectroscopy, AFM, Raman and XRD showed that the MPTMS was successfully attached onto the surface of the graphene nanoplatelets. Functionalized graphene/waterborne polyurethane acrylate (f-GNS/WPUA) nanocomposites were fabricated by UV-curing technology. The SEM and TEM images indicated that f-GNS could be well dispersed in the polymer matrix and improved the interfacial adhesion. With the incorporation of 1 wt% f-GNS, the thermal decomposition temperature of the composites was increased by 25 ∘ C. Meanwhile, the conductivity, hydrophobicity and tensile strength were increased. When the load was further increased, the performance of the composites showed varying degrees of reduction. However, the dielectric loss tangent (tan ) could be maintained at 0.08 or less and the electromagnetic shielding factor of the composites reached from 5 to 36 dB, showing a good electromagnetic shielding effect at a high content (2.5 wt% f-GNS). It was considered that f-GNS could disperse in the waterborne polyurethane well and crosslink with the polyurethane.

The support spring of a uniaxial micro-tensile system for testing micro-scale thin films is studied in this paper. Stresses of different shape springs are analyzed with the finite element method (FEM). The simulated results show that the stress of an S-shaped spring is lower compared with a U-shaped spring with the same dimensions (100 μm thick, 100 μm wide, 250 μm inner diameter and 5 turns). The maximum stress of the S-shaped spring is about 133 MPa when the displacement of 100 μm is imposed at one end of the spring along the lateral side. The number of turns has the most important effect on stress and stiffness of the S-shaped spring. Moreover, main stress concentration is symmetric in the spring system and it is located in the arc near to the two fixed ends in all springs. The spindle-shape support spring is fabricated by UV-LIGA technology according to analyzed results and calibrated by the specific device.

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