We have applied dicyclopentadiene (DCPD) resin for reinforcing pothole patch materials due to its unique properties –
low cost, low viscosity at beginning and ultra-toughness after curing, chemical compatibility with tar, tunable curing
profile through catalyst design. In this paper, we have designed a two layer structure – well compacted base layer and
DCPD reinforced 1-1.5" top layer – for pothole repair. By choosing two graded asphalt mixes, a porous top layer and
fully compacted base layer was prepared after compaction and ready for DCPD resin infiltration. The DCPD curing and
infiltration profile within this porous top layer was measured with thermocouples. The rutting resistance was tested with home-made wheel rutter. The cage effect due to the p-DCPD wrapping was characterized with wheel penetration test. The results showed that this two layer structure pothole repair has greatly improved properties and can be used for pothole repair to increase the service life.
The potholes and alligator cracks in the asphalt pavement of our country's roadways have become an annoying part of
our daily life. In order to reinstate and maintain our pavement infrastructure integrity and durability, we have identified
dicyclopentadiene (DCPD) resin for this purpose due to its unique properties - low cost, low viscosity at beginning and
ultra-toughness after curing, chemical compatibility with tar, tunable curing profile due to catalyst design. DCPD resin
can penetrate into high porous pavement area to reinforce them and block water or moisture seeping channels. It also can
strongly bond the pothole patches with original pavement, and hold them together for a whole. With the catalyst design,
DCPD could apply for all the weather, cold or hot, wet or dry. In this paper, we will investigate the DCPD reinforcement
for cold mix and hot mix for pothole repair, as well as the bonding strength improvement between repair materials and
original pavement, and show that DCPD is promising materials for application in reinforced pothole patching materials.
A cost-efficient technique for full-chip source and mask optimization is proposed in this paper. This technique has two
components: SMO source optimization for full-chip and flexible mask optimization (FMO). During the technology
development stage of source optimization, a novel pattern-selection technique was used to identify critical clips from a
full-set of design clips; SMO was then used to optimize the source based on those selected critical-clips. This pattern-selection
technique enables reasonable SMO runtime to optimize the source that covers the full range of patterns. During
the process development stage and product tapeout stage, FMO is employed. The FMO framework allows the use of
different OPC computational techniques on different chip areas that have different sensitivities to process variations.
Advanced OPC methods are applied only where they are needed, therefore achieving optimum process performance with
the least tapeout and mask cost.
Dielectric elastomer actuators have attracted a great deal of attention thanks to their remarkably large actuation strain and
energy density. Several different design concepts and configurations have been fabricated for many proposed
applications. However, high rates of failure and short lifetime caused by dielectric breakdown have prevented their use in
commercial applications. Employing single-walled carbon nanotube electrodes of tens of nanometer thickness and a
coating of dielectric oil on the electrode surface, the actuators can be operated continuously at larger than 150% area
strain for longer than 1500 minutes without terminal failure. As a comparison, under the same test conditions, actuators
with carbon grease electrodes can be driven for less than 60 minutes before terminal failure. It has been demonstrated
that the carbon nanotube electrodes endow the actuators with the ability to self-heal following localized dielectric failure,
which should make them more amenable to practical applications.
Polyaniline nanofibers (Pani nanofibers) have exhibited high performance and fault tolerant properties for dielectric
elastomer actuator devices. Electrodes comprised of uniformly sprayed Pani nanofibers in thicknesses 0.7 μm, 1.1 μm,
1.3 μm, and 1.5 μm have shown the following high strains: 65% in area for 0.7 μm electrodes at 3 kV, 97% in area for
1.1 μm thick electrodes at 3.5 kV, 84% in area for 1.1 μm thick electrodes at 3 kV, and 114.% in area for 1.5 μm thick
electrodes at 3.5 kV. Optimal performance was achieved with actuators with electrodes 1.1 μm thick, which
demonstrated self-healing properties at 3 kV. These actuators displayed a preserved strain of 91% after the clearing and
sustained a 93% area strain for 10 minutes at 3 kV. Devices with 1.1 μm thick electrodes were also able to perform 700
actuation cycles over a total duration of 75 minutes with a pulsed half-sinusoidal voltage of 3 kV. Mechanical
compliance tests performed on a film with a 1.1 μm thick Pani nanofiber electrode reveals that the electrode material
does not significantly alter the mechanical properties of the film. The estimated Young's modulus was found to be 32
MPa for the film with the electrode and 31 MPa for the film itself.
Dielectric elastomer actuators which consist of an electrode/dielectric elastomer/electrode sandwich structure show
greater than 100% electromechanical strain performance when high electrical field is applied. The strain in the dielectric
elastomer film occurs due to attraction of opposite charges across the dielectric film and repulsion of similar charges on
each compliant electrode. Structural defects present in these elastomers such as gel particles, uneven thickness, and stress
concentration may cause dielectric breakdown, leading to premature failure during continuous or repeated actuations.
Dielectric breakdown consequently reduces production yield and device lifetime. Carbon nanotubes (CNTs) have been
introduced as compliant electrodes for dielectric elastomers. Higher than 100% electromechanical strain was obtained
with ultrathin CNT electrodes due to the high aspect ratio and the high electrical conductivity of the nanotubes. These
ultrathin CNT electrodes also exhibit fault-tolerance in dielectric elastomers through the local degradation of CNTs
during dielectric breakdown. The degraded areas electrically isolate the defects, while keeping the rest of the elastomer
active. The "self-clearing" electrodes significantly increase the lifetime of the dielectric elastomers, making the dielectric
elasomer actuator much more reliable.
Dielectric elastomer actuators exert strain due to an applied electric field. With advantageous properties such as high efficiency and their light weight, these actuators are attractive for a variety of applications ranging from biomimetic robots, medical prosthetics to conventional pumps and valves. The performance and reliability however, are limited by dielectric breakdown which occurs primarily from localized defects inherently present in the polymer film during actuation. These defects lead to electric arcing, causing a short circuit that shuts down the entire actuator and can lead to actuator failure at fields significantly lower than the intrinsic strength of the material. This limitation is particularly a problem in actuators using large-area films. Our recent studies have shown that the gap between the strength of the intrinsic material and the strength of large-area actuators can be reduced by electrically isolating defects in the dielectric film. As a result, the performance and reliability of dielectric elastomers actuators can be substantially improved.
This paper describes new electroelastomer films that exhibit high actuation performance at zero to minimal mechanical prestrain. Prestrain is generally required for electroelastomers, also known as dielectric elastomers, such as the VHB 4910 acrylic elastomer, to obtain high electromechanical strain and high elastic energy density. However, the prestrain can cause several serious problems, including the use of a prestrain-supporting structure, a large performance gap between the active materials and packaged actuators, instability at interfaces between the elastomer and prestrain-supporting structure, and stress relaxation. We have introduced a polymerizable and closslinkable liquid additive into highly prestrained acrylic films and subsequently cured the additive to form the second elastomeric network. In the as-obtained Interpenetrating Polymer Networks (IPN), the additive network can effectively support the prestrain of the acrylic films and consequently eliminate the external prestrain- supporting structure. The IPN composite films without external prestrain exhibit electrically-induced strains up to 233% in area, comparable to the VHB 4910 films under high prestrain.
We present recent developments in etchless fabrication techniques for defining low-loss waveguides in polymers. Photobleached waveguides with optical propagation loss equal to the inherent loss of the core materials have been fabricated, as well as Mach-Zehnder modulators with 4.5 volt driving voltage and fiber-to-fiber insertion loss of 8 dB. In terms of new configurations, a novel linearized directional coupler modulator that has a 10 dB enhancement in the dynamic range compared to conventional Mach-Zehnder modulators is presented. We report on the design and fabrication of polymer digital optical switches with switching voltages of 7 volts and extinction ratios greater than 20 dB. Simultaneous serrodyne frequency shifting and high-frequency phase modulation in a polymer phase modulator are demonstrated in order to simplify the setup required to implement two-color heterodyne ranging. Finally, we propose implementations of optical signal processors based on polymer optical delay lines, couplers, and electrooptic modulators, and discuss their applications to optical signal processing.