Performance of asphalt mixtures depends on the properties of its constituent materials, mixture volumetrics, and external factors such as load and environment. An important material property that influences the performance of an asphalt mixture is the surface free energy of the asphalt binder and the aggregate. Surface free energy, which is a thermodynamic material property, is directly related to the adhesive bond energy between the asphalt binder and the aggregate as well as the cohesive bond energy of the asphalt binder. This thermodynamic material property has been successfully used to select asphalt binders and aggregates that have the necessary compatibility to form strong bonds and resist fracture. Surface free energy, being based on thermodynamics, assumes the asphalt binder is a brittle elastic material. In reality, the asphalt binder is not brittle and dissipates energy during loading and unloading. The total work of fracture is the culmination of all energy inputted into the sample to create two new surfaces of unit area and is dependent on the test geometry and testing conditions (e.g., temperature, loading rate, specimen size, etc.). The magnitude of the bond energy (either adhesive or cohesive) can be much smaller in magnitude when compared to the total work of fracture measured using mechanical tests (i.e., peel test, pull-off test, etc.). Despite the large difference in magnitude, there exists evidence in the literature supporting the use of the bond energy to characterize the resistance of composite systems to cohesive and/or adhesive failures. If the bond energy is to be recognized as a useful screening tool by the paving industry, the relationship between the bond energy and total work of fracture needs to be understood and verified. The effect of different types of modifications (addition of polymers, addition of anti-strip agents, and aging) on the surface free energy components of various asphalt binders was explored in order to understand how changes in the surface free energy components are related to the performance of the asphalt mixtures. After the asphalt binder-aggregate combination was explored, the next step was to study how the surface free energy of water was affected by contact with the asphalt binder-aggregate interface. Aggregates, which have a pH of greater than seven, will cause the pH of water that contacts them to increase. A change in the pH of the contacting water could indicate a change in its overall surface free energy, which might subsequently increase or decrease the water's moisture damage potential. With surface free energy fully explored, the total work of fracture was measured using pull-off tests for asphalt binder-aggregate combinations with known surface free energy components. In order to fully explore the relationship between bond energy and total work of fracture, temperature, loading rate, specimen geometry, and moisture content were varied in the experiments. The results of this work found that modifications made to the asphalt binder can have significant positive or negative effects on its surface free energy components and bond energy. Moreover, the results from the pull-off tests demonstrated that a relationship exists between bond energy (from surface free energy) and total work of fracture (from pull-off tests), and that surface free energy can be used to estimate the performance of asphalt binder-aggregate combinations.

In this study, we want to realize the influence of temperature and mechanical rubbing on the surface free energy and wettability of liquid crystal(LC) of polyimide(PI) thin films. In different surface conditions, we use the LC that was dropped on to the surface of the sample and become stable to explore the wettability of the surface. We also observe the phenomenon and influence of the LC on the PI with increasing surface temperature. We utilize hot stage and contact angle measuring system to obtain the surface free energy to realize the surface of the PI and measure the contact angle of LC in different temperature to realize the wettability of the PI. We found that the increase of the surface temperature leads to the decrease in the surface free energy of the PI and the contact angle of the FLC on the PI. The increase of the surface temperature causes the stabilization in the surface polar energy and the LC contact angle of the unrubbed PI. But the increase of the surface temperature causes the increase in the surface polar energy and the decrease of the LC contact angle of the rubbed PI. In the anti-parallel-direction to the rubbing direction the rubbed PI exhibits better wettability.

In this study, we want to realize the influence of temperature on the ferroelectric liquid crystal flow and rubbing strength on the surface free energy of the polyimide thin film. The rubbing strength is determined by pile impress and the number of rubbing. The surface energy of the samples is measured. On the other hand the ferroelectric liquid crystal flow on the polyimide thin film was observed using a polarizing microscope. We found that the polyimide film treated by rubbing the surface properties will become non-uniformity. When the number of rubbing increased to a certain extent, polar energy is not changed, white disperse energy is continued to show fluctuations. In liquid crystal flow observation, we found that when the polyimide thin film temperature is low, the flow of ferroelectric liquid crystal is relatively slow, and its flow direction is in rubbing direction. When the polyimide thin film temperature is high, ferroelectric liquid crystal has two-dimensional flow. In addition to the direction of the original rubbing direction, but also increased the flow in the direction of the vertical rubbing.

Reflectance anisotropy spectroscopy is a non-contact technique for surface detection. which means through the optical reflection from surface of the substrate measured. Because of its high sensitivity, RAS is used for in real-time control of semiconductor epitaxy. On our study, RAS is used to study the surface characteristics of liquid crystal alignment layer. We used rubbing for polyimide film to achieve alignment purposes. The rubbing strength is determined by adjusting the pile impress and the number of rubbed. We found that the anisotropy spectroscopy will appear after rubbing. And the strength of RA signals changes with photon energy of the probe beam. The pretile angle of the liquid crystal sandwiched in between rubbed PI show certain degree correlation with RA strength. In addition, using surface free energy measurement to explore the relationship with pretilt angle and try to connect three of them. We also tried to measure the reflection signal from the sample back. We found the signal of sample back would decay in UV region and it may be a result of UV absorption in the substrate.

In this study we use PDMS thin films to fabricate of multi-domain surface. PDMS gets the characteristic of good physical properties and chemical, not only low surface free energy, flexible, also has low toxicity, low cost and can protect our environment. We used the DI water that was dropped on the PDMS thin film surface and became stable to explore the wettability of the surface, and we had a discussion about when liquid crystal dropped on the PDMS thin film surface. Then we also observe the phenomenon that was liquid crystal will shift a little distance and we used the optical image to analyze our device.

Rubbing on polyimide thin film surface is an important procedure of alignment in the commercial display industry. Present on the surface of friction anisotropy, there will be corresponding to the pre-tiltangle. Monitoring and quality controlling of rubbing procedure will be the major issue. Reflection Anisotropy Spectroscopy is a powerful monitoring technology. Reflection Anisotropy Spectroscopy is a non-destructive detective system. Through optical method we could get property of our samples without damaging. After our process of survey, samples could be used in next manufactured step. In this thesis, we detected that monomers would occur some changes in a small amount in room temperature. We could find those changes effect the peak region of RA spectra and the feature in pretilt angle.

Mechanical Rubbing still is an useful alignment method in this time. In this study, we investigated the surface wettability of rubbed polyimide(PI) thin film. By using contact angle measurements, we found the surface free energy have strong connection with surface roughness in different rubbing times. We also discussed the wettability of rubbed PI thin film in parallel and anti-parallel of rubbing direction. We found that if we rubbed PI thin film 3 times in 0.3mm depth then the structure of SSFLC is more uniform than the alignment effect of other rubbing times and we found that the values of polar energy in parallel and anti-parallel of rubbing direction are very close. In the other part of study, we degenerated the polyimide before coating. We found that the reflection anisotropic spectrum(RAS) have a blueshift and the rubbing strength will be more influential in the wettability of PI thin film than the film with no degenerate process.

In the present studies we investigated the effects of mechanical rubbing on the surface characteristics of polymer liquid crystal alignment layers. Contact angles of water droplets in contacted with the rubbed polyimide were measured using a surface tension meter, and the surface free energy of the polymer thin films were evaluated. We found that the contact angle of water and surface free energy on rubbed polyimide is anisotropic, and rubbing caused decrease in surface free energy and wettability of the polyimide surface. It was also seen that the contact angle hysteresis and the surface free energy measured in the direction parallel to the rubbing direction is smaller than that in the direction anti-parallel to the rubbing direction. We found that when the pile impression of the velvet fibers is 0.3 mm and the cumulative number of rub is 3 times, the contact angle hysteresis in direction parallel or anti-parallel to the rubbing direction will to be close. Be suitable choosing rubbing conditions, the SSFLCs without zigzag defects was produced. The pretilt angle and the response time of liquid crystal increased with the cumulative number.

The liquid-crystal display because matches to the method is different , common has the TN monitor , the STN monitor , and the MVA monitor . Because these match to the method difference , therefore liquid crystal molecule pretilt angle is also different . Present liquid crystal molecule pretilt angle choice way includes : (1) Chooses the different polyimide material , after specific rubded intensity , but produces specific pretilt angle. (2) Uses low pretilt angle the polyimide material , mixes high pretilt angle according to the different proportion the polyimide material , but achieved accent of the pretilt angle changes . But in this research proposed double alignment layers , takes the first floor by homotropic layers , uses homogenous layers does for the upper formation , the surface free energy of the alignment layer can be easily controlled by adjusting the thickness of the top polyimide layer, similarly may achieve the accent to change liquid crystal molecule pretilt angle the effect . And may compensate the liquid crystal display to be insufficient because of rubbed polyimide , but has the question which dark condition is exposed , has a higher contrast gradient . Because this experiment scope accent changes the effect in liquid crystal molecule higher pretilt angle good , also kneading board various regions liquid crystal molecule pretilt the angle uniformity is higher , therefore may effectively apply on various types homotropic liquid crystal display component , for example: MVA , VA-STN , DSTN liquid-crystal display .

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