Amir Ameli

Amir Ameli
University of Massachusetts Lowell | UML · Department of Plastics Engineering

PhD - Mechanical Engineering

About

175
Publications
45,304
Reads
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4,350
Citations
Citations since 2017
50 Research Items
3631 Citations
20172018201920202021202220230200400600800
20172018201920202021202220230200400600800
20172018201920202021202220230200400600800
20172018201920202021202220230200400600800
Additional affiliations
August 2019 - present
University of Massachusetts Lowell
Position
  • Professor (Assistant)
January 2015 - August 2019
Washington State University
Position
  • Professor (Assistant)
March 2011 - December 2014
University of Toronto
Position
  • PDF

Publications

Publications (175)
Article
A method is presented to characterize the fracture resistance and interlayer adhesion of fused deposition modeling (FDM) 3D printed materials. Double cantilever beam (DCB) specimens of acrylonitrile butadiene styrene (ABS) were designed and printed with a precrack at the layers' interface. The DCBs were loaded in an opening mode and the load-displa...
Article
A class of microcellular polymer nanocomposites of multi-walled carbon nanotubes (MWCNT) is reported that exhibits a stable and significantly high dielectric permittivity coupled with a stable and low dielectric loss in a wide range of frequency. Polypropylene (PP)-MWCNT nanocomposites with a cellular structure were prepared by melt mixing followed...
Article
Foamed and solid polypropylene/carbon fiber (PP–CF) composites containing various CF contents (0–10 vol.%) were injection-molded. Foamed composites were achieved using dissolved pressurized nitrogen gas. The effects of foaming on the fibers inter-connectivity and orientation, electrical percolation threshold, through-plane electrical conductivity,...
Conference Paper
Multifunctional composites are in high demand where a material needs to simultaneously satisfy several functional requirements. Bipolar plates of polymer electrolyte membrane fuel cells are great examples of this kind, requiring very high electrical and thermal conductivities together with good mechanical properties and environmental durability. Co...
Conference Paper
Full-text available
The purpose of this study was to determine the suitability of recycled high-density polyethylene /polypropylene (rHDPE/PP) blend for in-situ foam 3D printing process. Semi-crystalline polymers such as HDPE and PP undergo high shrinkage and warpage during cooling, which makes their 3D printing a challenging task. Thus, another objective of this work...
Conference Paper
Full-text available
The purpose of this study was to investigate the feasibility of in-situ foaming in fused filament fabrication (FFF) process. Development of unexpanded filaments loaded with thermally expandable microspheres, TEM is reported as a feedstock for in-situ foam printing. Four different material compositions, i.e., two grades of polylactic acid, PLA, and...
Conference Paper
Full-text available
The purpose of this study was to investigate the effect of flow rate and print speed on the density and microcellular structure of polylactic acid (PLA) foams printed via fused filament fabrication (FFF) process. Unexpanded filaments loaded with thermally expandable microspheres (TEMs), at 2.5 wt.%, were prepared as a feedstock for in-situ foam pri...
Article
This work reports the fabrication and characterization of entirely biobased composites made with polylactic acid (PLA) and deep eutectic solvent (DES)-extracted lignin. White fir sawdust and corn stover were used as feedstocks to extract sawdust lignin (SDL) and corn stover lignin (CSL). Commercial alkali lignin (CAL) was also used as a baseline. P...
Article
A facile manufacturing method to enable the in situ foam 3D printing of thermoplastic materials is reported. An expandable feedstock filament was first made by incorporation of thermally expandable microspheres (TEMs) in the filament during the extrusion process. The material formulation and extrusion process were designed such that TEM expansion w...
Conference Paper
Traditional conductive polymer nanocomposite (CPN) liquid sensors have been studied for many years. However, they suffer from low sensitivity due to insufficient surface area and access points to the solvent. With increasing demand for highperformance smart sensors, the traditionally fabricated liquid sensors need major improvements in their perfor...
Article
Additive manufacturing technologies such as fused filament fabrication (FFF) allow the production of metastructures with global properties that can be tailored to their specific application. This study simulated and optimized an auxetic re-entrant structure with a stiffness gradient for enhanced energy absorption with low acceleration peaks under d...
Conference Paper
Full-text available
This study reports the effect of carbon fiber (CF) on the fracture toughness of 3D printed carbon fiber/ acrylonitrile butadiene styrene (CF/ABS) composites. Chopped carbon fiber was compounded with ABS to prepare CF/ABS filaments containing 0-25 wt.% CF. Compact tension specimens were designed, 3D printed, and tested to measure the composites' mod...
Conference Paper
Full-text available
There is an ever increasing need for sustainable and biobased materials. Plant-based feedstock such as cellulose and lignin can potentially become competitive resources as alternatives to fossil-based materials. Lignin as an inexpensive feedstock has been examined toward preparing polymer composites. It however faces some challenges including its d...
Article
Materials that are low cost and lightweight are essential for future automotive and aerospace industries. While carbon fibers have been shown to achieve high mechanical properties for high-end applications, their high cost has generated interest to find cost-effective alternatives. The recent advances in recycling carbon fibers has created an oppor...
Article
Research on lightweight products for transportation industry, to address fuel efficiency and lower carbon footprint, has attracted great attention due to public environmental awareness. Polymer composites containing carbon fiber are boosted by automotive original equipment manufacturers (OEMs) as a replacement for steel. However, their high cost ha...
Article
Conductive filler/polymer composite foams (CPC) with micro-/nano-scale bubbles have attracted much attention due to their various advantages. Understanding the evolution of electrical behavior in CPC foams is important for their functional application. There have been many experimental investigations of the electrical behavior of CPC foams, but how...
Article
In this work, the structural evolution of conductive polymer composites (CPCs) in response to mechanical deformation (uniaxial and biaxial compressive and tensile strains) is theoretically modeled and experimentally verified. The structural responses in mechanically deformed CPCs were simulated by incorporating the corresponding topological changes...
Article
Full-text available
A novel polyvinyl alcohol (PVA)/calcium carbonate-based double-layer cationic dye adsorbent was developed. Polyvinyl alcohol (50 wt %) and calcium carbonate (50 wt %) were used together with borax as a cross-linking agent. The nanocomposite was prepared using only water, without the need for any toxic solvent or hazardous chemical. The final sample...
Article
Full-text available
Ternary composites of flexible thermoplastic polyurethane (TPU), lead zirconate titanate (PZT), and multiwalled carbon nanotubes (MWCNTs) with very high dielectric permittivity (εr) and low dielectric loss (tan δ) are reported. To assess the evolution of dielectric properties with the interactions between conductive and dielectric fillers, composit...
Conference Paper
Full-text available
Layered multi-materials of dissimilar polymers and their nanocomposites offer new opportunities as smart materials and structures. A critical aspect of such structures is the quality of interlayer adhesion between dissimilar polymer matrices. This work reports the development of asymmetric double cantilever beam (ADCB) specimens of dissimilar polym...
Article
Foaming is a potential method to prepare high-performance, lightweight, composite materials with enhanced electrical properties. Here, a theoretical model and its experimental verification are presented to assess the evolution of electrical percolation threshold and conductivity as a bubble grows during the foaming of conductive filler/polymer comp...
Article
Environmentally friendly, sustainable, and high-performance thermal insulators are in high demand. Petroleum-based insulator foams usually have high thermal conductivity and pose health hazards. Here, we report ultralight composite foams that are highly strong, elastic, and super-insulating. The foams are composed of nanocrystalline cellulose (NCC)...
Article
Full-text available
The sensitivity enhancement of piezocomposites can realize new applications. Introducing a cellular structure into these materials decreases the permittivity and thus increases their sensitivity. However, foaming of piezocomposites is challenging because of the high piezoceramic loading required. In this work, heat-expandable microspheres were used...
Article
Conductive polymer composites (CPCs) with high electrical and thermal conductivities are demanded for bipolar plates of fuel cells. In this work, CPCs of polycarbonate (PC) filled with carbon nanotube (CNT), carbon fiber (CF), graphite (G), and their double and triple hybrids were prepared using solution casting method followed by compression moldi...
Article
Full-text available
Fabricating complex sensor platforms is still a challenge because conventional sensors are discrete, directional, and often not integrated within the system at the material level. Here, we report a facile method to fabricate bidirectional strain sensors through the integration of multiwalled carbon nanotubes (MWCNT) and multimaterial additive manuf...
Conference Paper
Additive manufacturing is an emerging method to produce customized parts with functional materials without big investments. As one of the common additive manufacturing methods, fused deposition modeling (FDM) uses thermoplastic-based feedstock. It has been recently adapted to fabricate composite materials too. Acrylonitrile butadiene styrene (ABS)...
Conference Paper
Full-text available
The demand for clean and sustainable energy sources continuously increases. One of the promising ways to provide electrical power is using fuel cells. Polymer electrolyte membrane fuel cell (PEMFC) represents the most common type of fuel cells. However, PEMFCs have not yet been fully commercialized because of the high cost and low performance. A ma...
Conference Paper
Full-text available
Fused deposition modeling (FDM) is highly commercialized Rapid Prototyping (RP) technology for its ability to build complex parts with low cost in a short period of time. The process parameters in the FDM play a vital role in the mechanical properties of the polymeric parts. Most of the research studies show that the variable parameters such as ori...
Article
Full-text available
This study aims to establish the relationships between the process parameters, mesostructural features (interlayer neck and void sizes), and the fracture resistance of 3D printed parts. The proposed method enables the decoupling of bond quality and mesostructure effects on the overall fracture behavior. Double cantilever beam specimens of acrylonit...
Article
Three-dimensional printing (3DP) has attracted a considerable amount of attention during the past years, being globally recognized as one of the most promising and revolutionary manufacturing technologies. Although the field is rapidly evolving with significant technological advancements, materials research remains a spotlight of interest, essentia...
Article
Full-text available
We developed a simple analytical model to describe the instantaneous location and angle of rod-like conductive fillers as a function of cell growth during the foaming of conductive polymer composites (CPCs). First, we modelled the motion of the fillers that resulted from the growth of one cell. Then, by taking into account the fillers located at th...
Article
We investigated electrically conductive nanocomposites made of thermoplastic vulcanizate (TPV) and multiwalled carbon nanotubes (CNT) that exhibit highly enhanced stretchability, low electrical percolation threshold, and improved electromechanical durability after cyclic loading. The TPV/CNT nanocomposites were fabricated by compounding the pre-vul...
Conference Paper
Full-text available
As the soft robotics industry continues to grow, the need for new materials and simplified manufacturing techniques are essential. Of interest is the development of highly flexible strain sensors that are easily integrated into these robotic components. Current strain sensing solutions using piezoresistive materials often involve complex fabricatio...
Conference Paper
Additive manufacturing (AM) offers a new and unique method for the fabrication of functional and smart material and structures. In this method, parts are fabricated directly from a 3D computer model layer by layer. Fused deposition modeling (FDM) is the most widely adapted AM method. In this method, the feedstock is usually a thermoplastic-based ma...
Conference Paper
The sensitivity of piezoelectric/polymer composite materials is inversely proportional to their dielectric permittivity. Introducing a cellular structure into these composites can decrease the permittivity while enhancing their mechanical flexibility. Foaming of highly filled polymer composites is however challenging. Polymers filled with high cont...
Article
This study reports on the effects of the matrix's crystal type (α or γ crystal) and chain mobility on the electrical properties of polypropylene (PP)/carbon nanotube (CNT) composites. Isothermal crystallization of the composites was performed at various temperatures and under atmospheric and elevated pressures with supercritical carbon dioxide (scC...
Article
Full-text available
3D-printable, flexible, and conductive thermoplastic-based material was successfully developed for strain sensing applications. Thermoplastic polyurethane/multiwalled carbon nanotube (TPU/MWCNT) were compounded, their filaments were extruded, and the sensors 3D printed using fused deposition modeling. Mechanical, electrical, and piezoresistivity be...
Article
A framework was developed to predict the fracture toughness of degraded adhesive joints by incorporating a cohesive zone finite element (FE) model with fracture data of accelerated aging tests. The developed framework addresses two major issues in the fracture toughness prediction of degraded joints by significant reduction of exposure time using o...
Article
The effects of glycerol monosterate (GMS) and high-pressure butane on the phase-separation and crystallization of the hard segment (HS) of thermoplastic polyurethane (TPU) were investigated. Small and wide angle x-ray diffraction, polarized optical microscopy and atomic force microscopy were used to characterize the crystalline morphology of TPU un...
Article
Foam injection molding experiments were conducted to establish the relationships between process, microstructure and electrical conductivity in polypropylene-multiwalled carbon nanotube nanocomposites. The effects of injection flow rate, gas content, melt temperature, void fraction, and cavity location on the microstructure and conductivity were in...
Conference Paper
This Talk will address innovative future products for energy storage and electromagnetic interference (EMI) shielding applications through the integration of conductive filer/polymer composite (CPC) and physical foaming technologies. To achieve a desired level of performance for charge storage and/or EMI shielding, complicated and difficult-to-scal...
Conference Paper
Fused deposition modelling (FDM) is a 3D printing technique which has a thermoplastic polymer filament heated above glass transition temperature and is extruded through a nozzle to print layer by layer of a part. While stress and strain based experiments were performed on these components, fracture toughness data which is an important property of t...
Article
Incorporation of foaming technology into the injection moulding process of polypropylene/ carbon nanotube composites increases the electrical conductivity by more than six orders of magnitude while decreasing the density up to 30 %.
Conference Paper
In this research, an analytical model was developed to describe the instantaneous location and angle of short fibers as a function of cell growth during foaming of fiber-filled polymer composites. The fibers located at the center line between two cells were considered at first. The final fiber angle as a function of the corresponding cell size and...
Conference Paper
Over the last decades, carbon nanotube (CNT)-filled conductive polymer composites (CPCs) have demonstrated great potential as a highly desired class of advanced functional materials. The CNT content required for achieving the percolation threshold in the CPCs depends on several factors including the type and intrinsic electrical conductivity of the...
Conference Paper
Polylactic acid is one of the most promising bio-based candidates for the substitution of the traditional petroleum-based polymers. However, PLA has numerous drawbacks (e.g. brittleness and low melt strength) which limit its use in different applications such as packaging. In this work, we propose the concept of in situ microfibrillation as a means...
Conference Paper
We used an in-situ visualization technique to study the re-orientation and displacement of dispersed fibers in conductive polymer composites, fabricated by foam injection molding method. Composites of polystyrene/carbon-fiber were foamed using carbon dioxide. We observed that the carbon fibers, in the vicinity of cell nuclei, exhibited both rotatio...
Article
Blended powders semisolid forming was adapted to fabricate Al7075/Al2O3 composites. The process included powders uniform distribution, mechanical alloying, and semisolid compaction. Al7075 elemental powders (20 and 63μm) were incrementally added to ethanol solution under ultrasonic mixing. Al2O3 particles with different sizes (5 and 120μm) and weig...
Conference Paper
With increasing structural and functional applications of 3D printed materials, their mechanical performance is highly demanded. So far, stress- and strain-based experiments have been used to characterize the mechanical properties of fused deposition modeled (FDM) samples. In this work, a fracture-mechanics-based methodology was developed to charac...
Conference Paper
The electrical conductivity of conductive fiber/polymer composites is highly affected by the alignment of the fibers, as well as the fiber-to-fiber distance and contacts. While the formation and growth of gaseous cells result in the translational and rotational displacement of the fibers in foamed conductive polymer composites, the mechanism of the...
Conference Paper
Full-text available
In this research, a systematic analysis was conducted to clarify the foaming effects on the electrical percolation threshold of rod-like conductive fillers in polymer composites. In order to decouple the volume exclusion and the cell growth effects, instead of using the “final” volume content of filler in foamed samples the “initial” volume concent...
Conference Paper
Polypropylene-multiwalled carbon nanotube (PP-MWCNT) nanocomposite foams with various void fractions ranging from 0 to 40% were prepared using injection molding. Their microstructure, cellular morphology and dielectric properties were studied. The results indicated that overall the real permittivity increases with void fraction. However, the void f...
Conference Paper
Lightweight polypropylene/stainless-steel fiber (PP-SSF) composites with 15-35% density reduction were fabricated using foam injection molding and supercritical carbon dioxide (CO2). The electrical percolation threshold, electrical conductivity, and electromagnetic interference (EMI) shielding effectiveness (SE) of the PP-SSF composite foams were c...
Article
This cover image shows how manipulating the crystalline structure of carbon nanotubes (CNTs) can be employed to store electrical energy. It is observable that nitrogen heteroatoms and their sequent defects play the role of polarization centers and improve the charge storage capacity of CNT/polymer nanocomposites.
Article
We investigated the interactions between dispersed carbon fibers and growing cells in high-pressure foam injection molding experiments using a polystyrene/carbon-fiber/carbon-dioxide system with an in-situ visualization technique. We found that the fibers exhibited both translational and rotational displacements in close proximity to the growing ce...
Article
Undoped CNTs and N-CNTs were synthesized by chemical vapor deposition using Fe catalyst, and then melt-mixed in an APAM mixer with polyvinylidene fluoride (PVDF) to prepare the nanocomposites. The morphology, crystallinity, aspect ratio, nitrogen content, and nitrogen bonding type of CNTs, and the broadband dielectric properties of Undoped CNT/PVDF...
Conference Paper
The alignment and rearrangement of carbon fibers in high-pressure foam injection molding was explored by means of an in-situ visualization technique. The experiments were performed using polystyrene/carbon fiber composite as a model material system, and carbon dioxide as the blowing agent. It was demonstrated that the fibers exhibit both rotational...
Article
Full-text available
Melt blending is one of the most promising techniques for eliminating poly(lactic acid)'s (PLA) numerous drawbacks. However, success in a typical melt blending process is usually achieved through the inclusion of high concentrations of a second polymeric phase which can compromise PLA's green nature. In a pioneering research, we introduce the produ...
Conference Paper
A Monte Carlo simulation was built to estimate the percolation threshold of fibers in a system under different fiber orientations. A 3-D model was built. The orientation effect was modeled by introducing a degree of alignment in the randomly generated fibers via appropriate mathematical relationships and various degrees of uniaxial strain were appl...
Conference Paper
Full-text available
This study aims to improve the understanding of cell structure effects on electrical conductivity of conductive polymer composite (CPC) foams by identifying the fundamental mechanisms of conductivity. CPC foams of polystyrene/carbon nanotube with controlled cell morphologies were fabricated through varying processing conditions. Different cellular...
Article
In this study, we report the development of polylactide (PLA) bead foams with a double crystal melting peak structure. PLA bead foams with 3- to 30-fold expansion ratios and average cell sizes ranged from 350 nm to 15 μm were prepared. We found that the PLA's foam structure was significantly affected by the amount of perfected crystals (that is, cr...
Conference Paper
Conductive polymer composite (CPCs) usually exhibit a percolative behavior, i.e., a sudden rise in the conductivity upon the formation of 3-D interconnected networks of fillers at a critical filler concentration. The critical concentration plays a major role in the processability and cost-effectiveness of CPCs and it is affected by several paramete...
Conference Paper
Conductive polymer composites (CPCs) offer superior resistance to chemicals and corrosion, higher specific toughness and ductility, inexpensive processing, and lighter weight. Thus, they have many promising applications in energy storage, energy conversion, electromagnetic interference shielding, electrostatic discharge, thermal management, etc. Th...
Conference Paper
Foaming of thermoplastic composites has been traditionally regarded as an effective technique for the production of light-weight, eco-friendly, and economically viable products. In addition, our earlier attempts have proven that foaming of conductive polymer composites (CPCs) also resulted in enhancements in their electrical conductivity (via the d...