The effects of particle size on the interface bond energy in KTa0.5Nb0.5O3/ polyimide composites were investigated using the molecular dynamics method. The composites of polyimide and the KTa0.5Nb0.5O3 nanoparticles with different size (0.4 nm, 0.5 nm, 0.6 nm, 0.8 nm, 1.2 nm, and 1.4 nm) have been established and simulated using the Forcite program package of Materials Studio software. The calc...

A simple and practical method for coating palladium/silver nanoparticles on polyimide (PI) nanotubes is developed. The key steps involved in the process are silver ion exchange/reduction and displacement reactions between silver and palladium ions. With the addition of silver, the conductivity of the PI nanotubes is greatly enhanced. Further, the polyimide nanotubes with a dense, homogeneous co...

A new thermally conductive polyimide composite film has been developed. It is based on a dispersion of different particle sizes of boron nitride (BN) in a polyimide (PI) precursor, polyamic acid (PAA). Subsequently, thermal imidization of PAA at 350 degrees C produced the corresponding polyimide composites. 3-Mercaptopropionic acid was used as the surfactant to modify the BN surface for the dis...

High temperature shape memory polymers that can withstand the harsh temperatures for durable applications are synthesized, and the aromatic polyimide chains with flexible linkages within the backbone act as reversible phase. High molecular weight (Mn) is demanded to form physical crosslinks as fixed phase of thermoplastic shape memory polyimide, and the relationship between Mn and glass transit...

As an attractive dielectric material, polyimide has been widely used in the field of electronics, aerospace, and automobiles due to its useful mechanical properties and good chemical resistance. UV irradiation was considered to be the main factor related to the damage and failure of polyimide. Here the effects of UV irradiation on the surface morphology and microscale mechanical properties of p...

FBG sensors offer many advantages, such as a lack of sensitivity to electromagnetic waves, small size, high durability, and high sensitivity. However, their maximum strain measurement range is lower than the yield strain range (about 1.0%) of steel strands when embedded in steel strands. This study proposes a new FBG sensing technique in which an FBG sensor is recoated with polyimide and protec...

Thin films of Al2O3 grown using atomic layer deposition (ALD) techniques can protect polymers from erosion by oxygen atoms. To quantify this protection, polyimide substrates with the same chemical repeat unit as Kapton were applied to quartz crystal microbalance (QCM) sensors. Al2O3 ALD films with varying thicknesses were grown on the polyimide substrates. The ALD-coated polyimide materials wer...

In this study, the effects of fluorine treatment on surface properties, surface free energies, and dielectric constants of polyimide thin films were studied using X-ray photoelectron spectroscopy, contact angles, and dielectric characteristics, respectively. The glass transition temperature of fluorinated polyimide film gradually decreases with increasing fluorine pressure. The surface free ene...

A simple theoretical model of liquid crystal ͑LC͒ alignment by exposure to linearly polarized ultraviolet ͑UV͒ light is proposed. The model predicts a universal relationship describing the change of the LC anchoring direction with exposure times, and the changes of polarization direction for the case of a double linearly polarized UV exposure process. This relationship is quantitatively confirmed b...

The effect of force field type on the predicted elastic properties of a polyimide is examined using a multiscale modeling technique. Molecular Dynamics simulations are used to predict the atomic structure and elastic properties of the polymer by subjecting a representative volume element of the material to bulk and shear finite deformations. The elastic properties of the polyimide are determine...