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Finding new means to enhance the performance of triboelectric nanogenerators (TENGs) is an ongoing pursuit. We report a novel flexible TENG made of highly porous cellulose nanofibril (CNF)/polyethylenimine (PEI) aerogel film paired with polyvinylidene fluoride (PVDF) nanofiber mats that exhibits outstanding triboelectric outputs. Modifying CNF with PEI not only enhances the mechanical properties of the CNF/PEI aerogel, but also greatly improves the power density by 14.4 times due to the enhanced tribopositivity. The triboelectric performance is further improved by employing multiple layers of PVDF mats. The TENG made of the CNF/PEI aerogel paired with four layers of PVDF mats exhibited an 18.3 times and 97.6 times improvement in output voltage and power density, respectively, compared to the TENG made of one layer of PVDF mat. The peak output power density reached 13.3 W/m2 at a load resistance of 106 Ω. Furthermore, the novel TENG displays extraordinary sensitivity when used as a self-powered sensor. It can detect not only human motion like arm bending and footsteps, but also small forces like finger tapping, water dripping, and the vibration of the substrate it is attached to. Therefore, this study not only demonstrates a high performance TENG, but also provides new insights into the design, fabrication, and application of TENGs.

The ability to topographically mimic the surface features of collagen fibrils is an important step in the preparation of tissue engineering scaffolds. It is important to know which kinds of surface topographies of electrospun fibers are more favorable for cell growth. In this study, fibers with three kinds of hierarchical-structured surfaces were fabricated by electrospinning to mimic collagen fibrils. By combining thermally induced phase separation (TIPS) and non-solvent induced phase separation (NIPS), polycaprolactone (PCL) fibers with a porous surface were electrospun from PCL in a chloroform (CF)/dimethyl sulfoxide (DMSO) mixed solution. In addition, two additional types of fibrous membranes, with PCL fibers being the shish and decorated by PCL kebabs on the surface, were created by two different controlled homoepitaxic crystallization methods—the solution incubation method and the solvent evaporation method. It was found that the solvent evaporation method was more effective in forming kebabs and the primary optimal processing parameters were identified. The presence of pores on the fiber surfaces contributed to a much larger surface area and a higher total volume of pores. To investigate the cellular response on such scaffolds, 3T3 fibroblast cell and human umbilical vein endothelial cell (HUVEC) assays were conducted and the results indicated that both of the nanotopographies on the surfaces of the scaffolds improved cell viability and proliferation. Furthermore, the porous surface was more beneficial for enhancing cellular responses, which suggests better biocompatibility and greater potential to mimic collagen fibrils for tissue engineering application, and especially as scaffolds for endothelial layers in blood vessels.

This paper presents the experimental behavior of low-energy impact and quasi-static compression test of shifted-tri-axial structural wood-fiber-based composite panels made from laminated paper. The experimental results were analyzed based on design parameters and configurations of panels for the further design and optimization. The results showed that the face stiffness and strength was a significant factor to improve both impact performance and compressive performance. The panels made with additional carbon fiber fabric composite faces had higher energy absorption compared with the same panels made without it. The core configuration also affected the impact behavior of the panels, the foam filled core integrated with the shifted-tri-axial rib structure improved the impact load and absorbed more energy than the same panels without the foam. Further, the structure and size of the element in the core influenced the impact performance and energy absorption. The location for both compression and impact at the triangular lattice element center of the ribs had higher absorbed energy than the location at the hexagonal lattice element center of the ribs. A 3D contour surface map of maximum energy absorption was made based on the experimental data, the contour shows localized energy absorption based on the impact location on the core, the small triangular lattice element of the core had highest maximum energy absorption of panels. For both the quasi-static compression tests and the low-velocity impact tests, the panels with the same core configuration had similar compressive load–displacement trends during the early contact phase. However, the peak load was higher in compression than the peak load for the low-velocity impact for panels with the same configuration.

A technique that can be used to viably create triaxially strained bilayer graphene on any desirable location by simple patterning was developed. Unlike the conventional graphene strain engineering methods, the photolithographically defined spoke patterns and compressive strained Si3N4 layer deposited by plasma-enhanced chemical vapor deposition (PECVD) system enable the creation of locally confined triaxial strained bilayer graphene at the desire location by forming a unique tristar shaped wrinkle. The tristar shaped wrinkle was investigated with high resolution micro-Raman spectroscopy and atomic force microscopy (AFM) analyses, and confirmed that 0.38% of maximum triaxial compressive strain was created. Mechanical simulation was used to verify the strain distribution and confirm the strain value which was calculated from the Raman spectroscopy and AFM profile. The technique presented here not only provides a practical route to the creation of strained graphene at desired locations but also offers the potential of the creation of multiaxial strain in the graphene for various types of graphene-based electronic and optoelectronic devices.

A novel polydimethylsiloxane (PDMS)/cellulose nanocrystal flake (CNCF) composite triboelectric nanogenerator (CTG) using CNCFs as effective dielectrics exhibited a 10-times-enhanced triboelectric performance compared with its pure PDMS counterpart. Positive charges generated on the surface of the CNCFs during cyclic compression boosted electron transfer and induced extra charges. The CTG exhibited an instantaneous output power (density) of 1.65 mW (0.76 mW cm−2) under continuous operation.

Superhydrophobic and crosslinked poly(vinyl alcohol) (PVA)/cellulose nanofibril (CNF) aerogel microspheres were prepared via a combination of the water-in-oil (W/O) emulsification process with the freeze-drying process, followed by thermal chemical vapor deposition of methyltrichlorosilane. The oil phase and the cooling agent were judiciously selected to ensure that the frozen ice microspheres can be easily separated from the emulsion system. The silanized microspheres were highly porous with a bulk density ranging from 4.66 to 16.54mg/cm(3). The effects of the solution pH, stirring rate, and emulsifier concentration on the morphology and microstructure of the aerogel microspheres were studied. The highly porous structure of the ultralight aerogel microspheres demonstrated an ultrahigh crude oil absorption capacity (up to 116 times its own weight). This study provides a novel approach for the large-scale preparation of polymeric aerogel microspheres with well-controlled particle sizes that can be used for various applications including oil and chemical spill/leak clean-up.

A novel, simple, cost-effective, and scalable technique was developed to fabricate high-performance flexible piezoelectric nanogenerators (NGs) using porous cellulose nanofibril (CNFs)/poly(dimethylsiloxane) (PDMS) aerogel film. The porous CNF/PDMS aerogel film was prepared by coating a layer of PDMS on the porous surface of a compressed CNF aerogel film produced via an environmentally friendly freeze-drying process. The porous CNF/PDMS aerogel film was then sandwiched between two thin PDMS films, followed by two aluminum foils, to form the flexible NGs. Under periodic external mechanical deformation by an oscillator, the resulting flexible porous CNF/PDMS aerogel film-based NGs exhibited very stable and high output piezoelectric signals; namely, an open-circuit voltage (Voc) of 60.2 V, a short-circuit current (Isc) of 10.1 μA, and a corresponding power density of 6.3 mW/cm3. The electric power generated by these NGs was able to directly turn on 19 blue light-emitting diodes (LEDs) and charge a capacitor up to 3.7 V. Furthermore, these NGs also demonstrated excellent stability and durability. Considering their excellent piezoelectric performance, ease of large-scale manufacturing, and environmental friendliness, this technology provides a promising solution for developing practical, flexible, and self-powered electronic devices.

Wood pulp cellulose nanofibrils (CNF) thin film is a novel recyclable and biodegradable material. We investigated the microwave dielectric properties of the epoxy coated-CNF thin film for potential broad applications in flexible high speed electronics. The characterizations of dielectric properties were carried out in a frequency range of 1–10 GHz. The dielectric constant and loss tangent were extracted by using measurements of microstrip transmission lines that were built on the epoxy coated-CNF film and combined with Agilent Advanced Design System simulations. The RF property for the epoxy coated-CNF was compared to that of commercial polyethylene terephthalate film (PET). With the comparable microwave properties of non-biodegradable PET film, our study suggests that the epoxy coated-CNF film is a suitable biodegradable and environment-friendly substrate for flexible microwave and other applications.

This paper presents static and fatigue bending behavior for a wood-based structural panel having a slot and tab (S/T) construction technique. Comparisons were made with similarly fabricated panels without the S/T construction technique. Experimental results showed that both types of panels had similar bending properties in the static tests. However, the panels with S/T construction had better fatigue results. The failure modes were different for the two fabrication techniques. The panels without S/T debonded at the core:face interface. Whereas, the panels with S/T had cracks that propagated within the rib of the core after debonding damage at the core:face interface. The fatigue deflection-life relationship indicated that the S/T construction improved the connection between the faces and core. The S/T construction decreased the deflection growth rate that delayed panel failure. The fatigue stress-life relationship or degradation was better for the panels with S/T construction than the panels without the S/T construction.

The self-healing capability is particularly desirable for multifunctional polymeric materials because it can make the materials more reliable, reduce repair costs, and extend their lifetime in many applications. Herein, a multi-stimuli responsive self-healing metallo-supramolecular polymer nanocomposite exhibiting superior mechanical properties was developed and demonstrated. Terpyridine ligand-terminated polyurethane (PU) was prepared by in situ polymerization on the surface of multi-walled carbon nanotubes (CNTs). The terpyridine ligand-terminated CNT/PU prepolymers were dynamically crosslinked with the metal ion Zn2+ to obtain a metallo-supramolecular polymer nanocomposite. The tensile strength and tensile strain-at-break of the CNT/PU polymer nanocomposite increased from 14.2 MPa and 620% to 22.8 MPa and 1076%, respectively, with the addition of Zn2+. The Zn2+-coordinated metallo-supramolecular polymer nanocomposite showed a rare combination of strong, tough, and elastic mechanical properties and was able to self-heal via multiple stimuli, including remotely controlled near infrared (NIR) light (4.2 mW mm−2, 30 min), relatively low temperatures (90 °C, 1 h), and/or solvents, all with excellent healing efficiencies (i.e., higher than 93%) and short healing times. Therefore, this unique multi-stimuli responsive self-healing metallo-supramolecular polymer nanocomposite has the potential to provide advances in structural component, microelectronic and sporting equipment applications, to name just a few.

Piezoresistive polymer nanocomposites are highly desirable for flexible mechanical sensing applications. In this study, a family of multi-walled carbon nanotube (CNT)/elastomeric triisocyanate-crosslinked polytetrahydrofuran (ETC-PTHF) nanocomposites that are highly stretchable and highly sensitive to mechanical stimuli were designed, synthesized, and characterized. The CNTs in the CNT/ETC-PTHF nanocomposites were initially dispersed in the ETC-PTHF matrix uniformly, leading to a relatively high electrical conductivity. Upon stretching, both the degree of CNT alignment along the stretching direction and the degree of PTHF crystallinity increased consistently with the tensile strain. The strain-induced microstructure change adversely affected the CNT conducting pathways, thereby reducing the electrical conductivity of the nanocomposites. For instance, the electrical conductivity of the 15 wt% CNT/ETC-PTHF nanocomposites decreased by approximately 7.3%, 29.2%, and 19.76, 169.2 and 1291 times when the tensile strain was 1%, 5%, 50%, 250%, and 500%, respectively. The nanocomposite film was able to detect a mechanical stimulus (poking) weaker than the landing force of a mosquito. Furthermore, the nanocomposite film demonstrated rapid and highly sensitive responses to continuous finger motion. These new piezoresistive CNT/ETC-PTHF nanocomposites possess a number of desirable characteristics including ease of fabrication, low cost, and high sensitivity, thereby making them very promising candidates for applications in electronic skins, electronic textiles, and biomedical detectors.

Fully biobased chemically crosslinked anisotropic carboxymethyl cellulose (CMC)/cellulose nanofibril (CNF) aerogels were prepared using an environmentally friendly directional freeze-drying method. The resulting cellulose aerogels were characterized using various techniques. It was found that the CMC/CNF aerogel exhibited a honeycomb structure, and thus possessed anisotropic properties. Moreover, the fully biobased crosslinked organic aerogel possessed excellent mechanical properties based on both compression and three-point bending tests. For instance, it exhibited a remarkable compressive modulus (up to 10 MPa) along the vertical direction (parallel to the freezing direction) as well as a high flexural modulus (up to 54 MPa) perpendicular to the freezing direction. The effects of different aerogel densities and CNF contents on the mechanical properties of CMC/CNF aerogels have been studied. With increasing aerogel density or CNF content, the modulus and strength of the CMC/CNF aerogel increased in both compression and three-point bending tests. In addition, these cellulose aerogels also exhibited relatively low thermal conductivities (

The static and fatigue bending behavior of wood-fiber-based tri-axial engineered sandwich composite panels (ESCP) has been investigated by four-point bending tests. Fatigue panels and weakened panels (wESCP) with an initial interface defect were manufactured for the fatigue tests. Stress σ vs. number of cycles curves (S-N) were recorded under the different stress levels. The primary failure mode in the fatigue tests was observed in the shear zone (epoxy debonding), which was different from face failure in the pure bending zone for the static bending test. For residual bending (RB) test, epoxy debonding failure occurred between the pure bending zone and shear zone. Macro cracks along the core/face interface developed as the number of cycles increased during the fatigue life. The crack propagation or damage for the panels submitted to fatigue test can be described as a three-stage damage process of first non-linear portion, followed by linear damage accumulation, and lastly non-linear accelerated damage. Bending stiffness degradation at the higher load level had faster degradation during fatigue life. The dissipated energy of the panels was small due to the high stiffness of the materials.

Flexible infrared (IR)-responsive materials, such as polymer nanocomposites, that exhibit high levels of IR responses and short response times are highly desirable for various IR sensing applications. However, the IR-induced photoresponses of carbon nanotube (CNT)/polymer nanocomposites are typically limited to 25%. Herein, we report on a family of unique nanocomposite films consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a form-stable phase change material (PCM) that exhibited rapid, dramatic, reversible, and cyclic IR-regulated responses in air. The 3 wt % MWCNT/PCM nanocomposite films demonstrated cyclic, IR-regulated on/off electrical conductivity ratios of 11.6 ± 0.6 and 570.0 ± 70.5 times at IR powers of 7.3 and 23.6 mW/mm(2), respectively. The excellent performances exhibited by the MWCNT/PCM nanocomposite films were largely attributed to the IR-regulated cyclic and reversible form-stable phase transitions occurring in the PCM matrix due to MWCNT's excellent photoabsorption and thermal conversion capabilities, which subsequently affected the thickness of the interfacial PCM between adjacent conductive MWCNTs and thus the electron tunneling efficiency between the MWCNTs. Our findings suggest that these unique MWCNT/PCM nanocomposites offer promising new options for high-performance and flexible optoelectronic devices, including thermal imaging, IR sensing, and optical communication.

Superhydrophobic poly(vinyl alcohol) (PVA)/cellulose nanofibril (CNF) aerogels with a unidirectionally aligned microtubular porous structure were prepared using a unidirectional freeze-drying process, followed by the thermal chemical vapor deposition of methyltrichlorosilane. The silanized aerogels were characterized using various techniques including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and contact angle measurements. The structure of the aerogels fully filled with polydimethylsiloxane (PDMS) was confirmed by SEM and optical microscopy. The mechanical properties of the resulting PDMS/aerogel composites were examined using both compressive and tensile tests. The compressive and tensile Young's moduli of the fully filled PDMS/aerogel composites were more than 2-fold and 15-fold higher than those of pure PDMS. This study provides a novel alternative approach for preparing high performance polymer nanocomposites with a bicontinuous structure.

This paper presents experimental results of both quasi-static compression and low-velocity impact behavior for tri-axial bio-composite structural panels using a spherical load head. Panels were made having different core and face configurations. The results showed that panels made having either carbon fiber fabric composite faces or a foam-filled core had significantly improved impact and compressive performance over panels without either. Different localized impact responses were observed based on the location of the compression or impact relative to the tri-axial structural core; the core with a smaller structural element had better impact performance. Furthermore, during the early contact phase for both quasi-static compression and low-velocity impact tests, the panels with the same configuration had similar load-displacement responses. The experimental results show basic compression data could be used for the future design and optimization of tri-axial bio-composite structural panels for potential impact applications.

Films of polyvinylpyrrolidone (PVP)-stabilized silver nanowire (AgNW)/thermoplastic polyurethane (TPU) elastomer nanocomposites were fabricated and characterized. With increasing loading levels of AgNW, the transparency of the nanocomposite films was reduced, but their crystallization temperatures increased, suggesting that AgNW could serve as crystallization nucleating agents. The addition of AgNW also enhanced both the Young’s moduli and storage moduli of the nanocomposite films, but caused a reduction in their strain-at-break (from 536% to 304% with 1.5 vol.% AgNW) and ultimate strength (from 12.7 to 9.8 MPa with 1.5 vol.% AgNW). The specific toughness was the highest for nanocomposites with AgNW loading levels of 0.03 vol.% and 0.05 vol.%. In addition, the dielectric constant of the nanocomposite films with 1.5 vol.% AgNW was 9 times higher than that of pure TPU at 1 kHz, while the dielectric loss of all nanocomposite films studied was less than 0.2. Thus, AgNW/TPU elastomer nanocomposites with varying mechanical, dielectric, and thermal properties can be engineered by adding a small amount of AgNW. These nanocomposites can potentially be used for a wide range of applications including dielectric materials.

Cross-linked polyvinyl alcohol (PVA)–cellulose nanofibril (CNF) hybrid organic aerogels were prepared using an environmentally friendly freeze-drying process. The resulting PVA/CNF aerogel was rendered both superhydrophobic and superoleophilic after being treated with methyltrichlorosilane via a simple thermal chemical vapor deposition process. Successful silanization on the surface of the porous aerogel was confirmed by various techniques including scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), Fourier transform infrared spectroscopy (FTIR), and contact angle measurements. The silane-treated, cross-linked PVA/CNF aerogels not only exhibited excellent absorption performance for various types of oils (e.g., crude oil) or organic solvents (with a typical weight gain ranging from 44 to 96 times of their own dry weight), but also showed a remarkable scavenging capability for several types of heavy metal ions tested (e.g., Pb2+, Hg2+), making them versatile absorbents for various potential applications including water purification. Furthermore, these PVA/CNF aerogels demonstrated excellent elasticity and mechanical durability after silane-treatment as evidenced by the cyclic compression tests.

Hybrid organic aerogels consisting of polyvinyl alcohol (PVA), cellulose nanofibrils (CNFs), and graphene oxide nanosheets (GONSs) were prepared using an environmentally friendly freeze-drying process. The material properties of these fabricated aerogels were measured and analyzed using various characterization techniques including compression testing, scanning electron microscopy, thermogravimetric (TGA) analysis, Brunauer-Emmet-Teller (BET) surface area analysis, and contact angle measurements. These environmentally friendly, biobased hybrid organic aerogels exhibited a series of desirable properties including a high specific compressive strength and compressive failure strain, ultralow density and thermal conductivity, good thermal stability, and moisture resistance, making them potentially useful for a broad range of applications including thermal insulation.

Supercritical fluid (SCF) N2 was used as a physical foaming agent to fabricate microcellular injection-molded poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)–poly(butylene adipate-co-terephthalate) (PBAT)–hyperbranched-polymer (HBP)–nanoclay (NC) bionanocomposites. The effects of incorporating HBP and NC on the morphological, mechanical, and thermal properties of both solid and microcellular PHBV–PBAT blends were studied. NC exhibited intercalated structures in solid components, but showed a mixture of exfoliated and intercalated structures in the corresponding microcellular nanocomposites. The addition of NC improved the thermal stability of the resulting nanocomposites. The addition of HBP and NC reduced the cell size and increased the cell density of microcellular components. The addition of HBP and NC enhanced the degree of crystallinity for both solid and microcellular components. Moreover, with the addition of HBP, the area under tan d curve, specific fracture toughness, and strain-at-break of the PHBV-based nanocomposite increased significantly whereas the storage modulus, specific Young’s modulus, and specific tensile strength decreased.

Graphene nanosheets (GNS) were functionalized with 3,5-di(trifluoromethyl)-aniline to achieve homogeneous dispersion and favorable interfacial interactions in the poly(vinylidenefluoride-trifluorethylene-chlorofluoroethylene) P(VDF-TrFE-CFE) terpolymer matrix. The effects of functionalized GNS (FGNS) on the dielectric, mechanical, and electromechanical actuation properties of the FGNS/P(VDF-TrFE-CFE) terpolymer nanocomposites were systematically evaluated. It was found that incorporating FGNS into the P(VDF-TrFE-CFE) terpolymer, even at low loading levels (e.g., ∼1.0 vol%), increased the dielectric constant, Young's modulus, tensile strength, and electromechanical actuation performance of the resulting FGNS/P(VDF-TrFE-CFE) terpolymer nanocomposites drastically.

The effects of incorporating hyperbranched polymers (HBPs) and different nanoclays [Cloisite® 30B and halloysite nanotubes (HNT)] on the mechanical, morphological, and thermal properties of solid and microcellular poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) were investigated. According to the X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses, Cloisite 30B exhibited a combination of exfoliation and heterogeneous intercalation structure for both solid and microcellular PHBV–12% HBP–2% Cloisite 30B nanocomposites. TEM images indicated that HNTs were uniformly dispersed throughout the PHBV matrix. The addition of 2% nanoclays improved the thermal stability of the resulting nanocomposites. The addition of HBP+poly(maleic anhydride-alt-1-octadecene) (PA), Cloisite 30B, and HNT reduced the average cell size and increased the cell density of the microcellular components. The addition of (HBP+PA), Cloisite 30B, and HNT also increased the degree of crystallinity for both solid and microcellular components in comparison with neat PHBV. Also, with the addition of 12% (HBP+PA), the area under the tan-δ curve, specific toughness, and strain-at-break of the PHBV–HBP nanocomposite increased significantly for both solid and microcellular specimens, whereas the storage modulus, specific Young's modulus, and specific tensile strength decreased. The addition of 2% nanoclays into the PHBV–HBP nanocomposites improved the storage modulus, specific Young's modulus, and specific tensile strength of the PHBV–HBP–nanoclay-based nanocomposites, but they were still lower than those of the neat PHBV. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Poly(ethylene terephthalate) (PET) resin is one of the most widely used thermoplastics, especially in packaging. Because thermal and hydrolytic degradations, recycled PET (RPET) exhibits poor mechanical properties and lacks moldability. The effects of adding elastomeric modifiers, chain extenders (CE), and poly(butylene adipate-co-terephthalate), PBAT, as a toughener to RPET on its moldability and mechanical property were investigated. Melt blending of RPET with CE, thermoplastic elastomer (TPE), and/or PBAT was performed in a thermokinetic mixer (K-mixer). The blended materials were then injection molded to produce tensile specimens. Various techniques were used to study the mechanical properties, rheological properties, compatibility, and crystallization behavior of the RPET blends. By melt blending with proper additives, recycled PET regained its moldability, thereby enabling the recycling of RPET. Furthermore, the addition of CE greatly enhanced the mechanical properties of RPET. While the RPET and TPE blends also showed improved mechanical properties, the improvement was less significant and the blends were often immiscible due to the difference in polarities between RPET and TPE. Finally, it was found that the mechanical properties of RPET blends depended on the prior thermal history of the material and could be improved with an extra annealing step that increased the degree of crystallinity. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Solid and microcellular components made of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/poly (butylene adipate-co-terephthalate) (PBAT) blend (weight ratio of PHBV:PBAT = 30:70), recycled wood fiber (RWF), and nanoclay (NC) were prepared via a conventional and microcellular-injection molding process, respectively. Morphology, thermal properties, and mechanical properties were investigated. The addition of 10% RWF (both untreated and silane-treated) reduced the cell size and increased the cell density of the microcellular components. Also, the addition of 10% RWF (both untreated and silane-treated) generally increased the specific Young’s modulus and tensile strength, but decreased the specific toughness and strain-at-break in both solid and microcellular components. Moreover, unlike the neat PHBV/PBAT blend, microcellular PHBV/PBAT/RWF (both untreated and silane-treated) composites showed higher specific toughness and strain-at-break compared to their solid counterparts. In addition, higher specific toughness and strain-at-break was observed in the PHBV/PBAT/untreated-RWF composite compared with the PHBV/PBAT/silane-treated RWF composite, particularly in the microcellular components. The degree of PHBV crystallinity increased significantly in both solid and microcellular PHBV/PBAT/RWF composites although the degree of PHBV crystallinity in the solid components was slightly higher than that of their microcellular counterparts. The effects of adding 2% nanoclay on the properties of the PHBV/PBAT/silane-treated-RWF composite were also investigated. The nanoclays exhibited an intercalated structure in the composites based on XRD analysis and did not induce significant changes in the cell morphology and mechanical properties of the PHBV/PBAT/silane-treated-RWF composite. However, it did improve its thermal stability.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/coir fiber composites were prepared via both conventional and microcellular injection-molding processes. The surface of the hydrophilic coir fiber was modified by alkali- and silane-treatment to improve its adhesion with PHBV. The morphology, thermal, and mechanical properties were investigated. The addition of coir fiber (treated and untreated) reduced cell size and increased cell density. Further decrease in cell size and increase in cell density was observed for treated fibers compared with PHBV/untreated-fiber composites. Mechanical properties such as specific toughness and strain-at-break improved for both solid and microcellular specimens with the addition of coir fibers (both treated and untreated); however, the specific modulus remained essentially the same statistically while the specific strength decreased slightly. The silane-treated coir fiber composites showed the greatest improvement in specific toughness and strain-at-break among the treated-fiber composites. In addition, adding coir fibers (treated and untreated) also increased the degree of crystallinity of the PHBV composites. PHBV with treated coir fibers showed a higher degree of crystallinity compared with untreated coir fibers.

Solid and microcellular specimens made of poly (3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)/ poly(butylene adipate-co-terephthalate) (PBAT) blends with three different weight ratios (i.e., PHBV/PBAT = 98.5/1.5 (Y1000P), 45/55 (5010P), and 30/70 (6010P), respectively) were prepared via conventional and microcellular injection molding process, respectively. Various properties such as miscibility, cell morphology, thermal, and mechanical properties were investigated. Compared with the microcellular specimens, the solid specimens showed better miscibility. Increasing the PBAT content led to higher specific toughness and strain-at-break, but lower specific modulus and specific strength for both solid and microcellular specimens. In addition, increasing the PBAT content increased the average cell size, but decreased the cell density of the microcellular samples. Finally, the crystallinity of PHBV in the PHBV/PBAT blends decreased significantly with increasing PBAT content for both solid and microcellular specimens. POLYM. ENG. SCI., 50:1440-1448, 2010. © 2010 Society of Plastics Engineers.

As the expected life of dry cask storage installations increases, it becomes increasingly desirable to monitor the state and performance of the cask internals to ensure that they continue to safely contain the radioactive materials in the fuel. One aspect of this task is the monitoring of oxidation of the cladding. With this consideration in mind, Zircaloy-4 (Zr-4) cladding samples were exposed to air at 500[Formula: see text]C for various duration times to create thin corrosion oxide layers on the surface. The surfaces of the oxidized samples were then systematically scanned by Fourier Transform Infrared (FT-IR) spectroscopy to achieve the infrared (IR) interference spectra and study the relationship between the optical interference and the various thicknesses of the oxide layers. The profiles of the oxide layers were verified througth cross-sectional examination by Scanning Electron Microscopy. The IR interference patterns varied with oxide layer thickness, enabling the determination of oxide layer thickness of values, including half micron thick. Further analysis demonstrated that the interference oscillation period and the oscillation amplitude decreased with increasing oxide layer thickness. Combined with a physical model that describes the optical interference, the interference spectra were directly correlated to the oxide layer thickness quantitatively. The study provides the basis for an accurate, nondestructive and sensitive method to monitor the degree of zirconium-based cladding corrosion due to oxidation.

The effects of addition of hyperbranched polyesters (HBPs) and nanoclay on the material properties of both solid and microcellular polylactide (PLA) produced via a conventional and microcellular injection-molding process, respectively, were investigated. The effects of two different types of HBPs (i.e., Boltorn H2004® and Boltorn H20®) at the same loading level (i.e., 12%), and the same type of HBP at different loading levels (i.e., Boltorn H2004® at 6 and 12%), as well as the simultaneous addition of 12% Boltorn H2004® and 2% Cloisite®30B nanoclay (i.e., HBP–nanoclay) on the thermal and mechanical properties (both static and dynamic), and the cell morphology of the microcellular components were noted. The addition of HBPs and/or HBP with nanoclay decreased the average cell size, and increased the cell density. The stress–strain plots of all the solid and microcellular PLA-H2004 blends showed considerable strain softening and cold drawing, indicating a ductile fracture mode. Among the two HBPs, samples with Boltorn H2004® showed higher strain-at-break and specific toughness compared to Boltorn H20®. Moreover, the sample with Boltorn H2004® and nanoclay exhibited the highest strain-at-break (626% for solid and 406% for microcellular) and specific toughness (405% for solid and 334% for microcellular). Finally, the specific toughness, strain-at-break, and specific strength of microcellular samples were found to be lower than their solid counterparts.

The effects of adding epoxy-functionalized chain-extender (CE) and processing conditions such as die temperature on the cell morphology, volume expansion ratio (VER), open cell content (OCC), and crystallization of microcellular extruded polylactide (PLA) were investigated. When compared with pure PLA, the addition of talc decreased the average cell size and increased the cell density. Moreover, the simultaneous addition of talc and CE led to denser and more uniform cell structure up until 1.0% CE content. In general, the volume expansion ratio and open cell content of all the formulations decreased with the die temperature. The addition of talc decreased both VER and OCC, whereas the addition of CE increased both. The die temperature did not affect the degree of crystallinity significantly. The addition of talc increased the crystallinity, but the addition of CE decreased it. Finally, the molecular weight of PLA increased significantly with the addition of CE. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

The effects of adding an epoxy-based chain-extender (CE) on the properties of injection-molded solid and microcellular polylactide (PLA) were studied. PLA and PLA with 8 wt.% CE (PLA-CE) were melt-compounded using a twin-screw extruder. Solid and microcellular specimens were produced via a conventional and microcellular injection-molding process, respectively. Various characterization techniques including gel permeation chromatography, tensile testing and dynamic mechanical analysis, scanning electron microscopy and differential scanning calorimetry were applied to study the molecular weight, static and dynamic mechanical properties, cell morphology, and crystallization behavior, respectively. The addition of CE enhanced the molecular weight but decreased the crystallinity of PLA. The addition of CE also reduced the cell size and increased the cell density. Furthermore, the decomposition temperatures and several tensile properties, including specific strength, specific toughness, and strain-at-break of both solid and microcellular PLA specimens, increased with the addition of CE.

Polylactide (PLA)-recycled wood fiber (RWF) composites with a small amount of silane were compounded using a kinetic-mixer and molded using an injection molding machine. The molded PLA-RWF compo- sites were characterized using gel permeation chromatog- raphy, scanning electron microscope, X-ray diffraction, differential scanning calorimeter, tensile testing machine, and a dynamic mechanical analyzer. As observed in the stress-strain plots, the amount of necking before fracture decreased with an increasing RWF content. Similarly, the strain-at-break also decreased with the RWF content. The tensile strength remained the same irrespective of the RWF content. Both the tensile modulus and the storage modulus of the PLA-RWF composites increased with the RWF content. The degree of crystallinity of the PLA increased with the addition of RWF. No reduction in the number-average molecular weight (Mn) was observed for pure PLA and PLA-10%RWF-0.5%Silane composites af- ter injection molding; however, substantial reduction in Mn was found in PLA-20%RWF-0.5%Silane composites. Finally, a theoretical model based on Halpin-Tsai empiri- cal relations is presented to compare the theoretical results with that of the experimental results. V C 2008 Wiley Periodi

Polylactide–flax fiber composites with 1, 10 and 20 wt% fiber were melt-compounded and subsequently molded via the conventional and microcellular injection-molding processes. Silane was used as a coupling agent. The effects of fiber and silane content on cell morphology, static and dynamic mechanical properties, and crystallization properties have been studied. The average cell size decreased while the cell density increased with the fiber content. The degree of crystallinity increased with the fiber content. Silane treatment of fibers affected neither the cell morphology nor the degree of crystallinity. The toughness and strain-at-break of solid samples decreased with the fiber content while silane treatment increased both properties; however, neither fiber content nor silane treatment had much influence on the toughness and strain-at-break of microcellular samples. The specific modulus of both solid and microcellular samples increased with the fiber content. The specific strength of the solid and microc...

This paper presents a thin polymer surface coating approach to facilitate dispersion of poly(styrene-maleic anhydride) (SMA) copolymer-coated alumina (Al2O3) nanoparticles in polycarbonate (PC) using a high intensity thermokinetic mixer (K-mixer) and the optical properties of the resultant nanocomposites. Electron spectroscopy for chemical analyses (ESCA), energy filtered transmission electron microscopy (EFTEM), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM) were used to investigate the covalent bonding of polymer coating on the nanoparticles and the nanoparticle dispersion. The light transmittance of the PC/alumina nanocomposites was measured and compared with that of the transparent neat resin.

Biobased and biodegradable polylactide (PLA)-pine wood flour (PWF) composites were investigated as a means to reduce the overall material cost and tailor the material properties. The composites were prepared using a kinetic-mixer and an injection molding machine. The tensile modulus of the PLA-PWF composites increased with the PWF content whereas the toughness and strain-at-break decreased. The tensile strength remained the same irrespective of the PWF content (up to 40%). The storage modulus also increased with the PWF content. Additionally, composites containing PWF treated with silane showed higher storage modulus than those without the silane treatment. The area integration underneath the tan δ peaks decreased with increasing PWF, indicating that the PLA-PWF composites exhibited more elastic behavior with increasing PWF. The degree of crystallinity of the PLA-PWF composites increased significantly with the PWF content. Furthermore, the treatment of PWF with silane had a positive effect on its nucleating ability, as treated PLA-PWF composites showed higher crystallinity compared with their untreated counterparts. The morphology of the fracture surfaces were studied using a scanning electron microscope. Finally, a Halpin-Tsai analytical model to predict Young's modulus of PLA-PWF composites was presented to compare the theoretical results with that of experimental results. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Recycled paper shopping bag fibers were melt-compounded using a batch mixer with biobased/biodegradable polylactide (PLA) at 10 and 30 wt.% using silane as a coupling agent. These PLA/fiber composites were then injection molded to produce both solid and microcellular tensile bars. The mechanical properties (specific modulus, specific tensile strength, specific toughness, and strain at break) of the neat PLA and PLA composites were tested and the cell morphology of the microcellular samples was examined using scanning electron microscopy. It was observed that the addition of the recycled paper shopping bag fibers resulted in an increase in cell density and decrease in average cell size for the microcellular components when compared with the neat PLA. The addition of the fibers increased the specific modulus of both solid and microcellular components, and high fiber contents (30 wt.%) resulted in an increase in specific tensile strength, yet yielded a decrease in the strain at break and specific toughness. The storage modulus was also improved with the addition of 10 and 30 wt.% fibers for both solid and microcellular components.

In this study, polylactide (PLA)-multi-walled carbon nanotube (MWCNT) nanocomposites were melt-compounded using a twin-screw extruder. Solid and microcellular tensile bar specimens were produced via conventional and microcellular injection molding, respectively. Various characterization techniques were applied to study the static and dynamic mechanical properties, degree of MWCNT dispersion, cell morphology, and crystallization behavior. The addition of a small amount of MWCNTs led to a decrease in the cell size and an increase in the cell density of the microcellular PLA specimens. A transmission electron microscopy analysis of the PLA-MWCNT specimens revealed a higher degree of MWCNT dispersion in the microcellular PLA-MWCNT composite compared with its solid counterpart, indicating that the microcellular injection molding process further dispersed the MWCNTs. For both solid and microcellular specimens, the addition of 1.5 wt% MWCNTs reduced the specific strength, specific toughness and strain-at-break while exerting less impact on the specific modulus. The storage modulus was not affected significantly with the addition of MWCNTs, but was found to be higher for the microcellular specimens compared with their solid counterparts. Finally, the crystallinity of PLA increased with the addition of MWCNTs.

Microcellular injection molding is capable of producing lightweight, dimensionally stable plastic components with less material and energy. This process allows the material to be processed at lower temperatures and pressures, making it suitable for temperature-sensitive biobased plastics and/or additives. This paper presents the effects of adding montmorillonite nanoclay (Cloisite®20A and Cloisite®30B) on the mechanical properties (specific modulus, specific tensile strength, specific toughness, and strain at break) of both solid and microcellular polylactide components, as well as their effects on the cell morphology of the microcellular components. In general, the addition of nanoclay into biobased polylactide improved the specific moduli of both solid and microcellular components and facilitated the formation of smaller cell sizes and higher cell densities. Adding nanoclay also reduced the strain at break and the specific toughness of solid polylactide nanocomposite components. However, the strain at break and specific toughness of microcellular polylactide nanocomposite components were largely improved in comparison with microcellular polylactide components, especially when the loading level of the nanoclay was at 3% and 5%, presumably due to the lack of large voids, as well as the smaller cell size and higher cell density.

This article presents the development and characterization of transparent poly(styrene-r-maleic anhydride) (SMA)/alumina nanocomposites for potential use in optical applications. Chemically treated spherical alumina nanoparticles were dispersed in an SMA matrix polymer via the solution and melt-compounding methods to produce 2 wt % nanocomposites. Field emission scanning electron microscopy was used to examine the nanoparticle dispersion. When the solution method was used, nanoparticle reagglomeration occurred, despite the fairly good polymer wetting. However, through the coating of the alumina nanoparticles with a thin layer (ca. 20 nm) of low-molecular-weight SMA, reagglomeration was absent in the melt-compounded samples, and this resulted in excellent nanoparticle dispersion. The resultant nanocomposites were semitransparent to visible light at a 2-mm thickness with improved UV-barrier properties. Their impact strengths, tensile strengths, and strains at break were slightly reduced compared with those of their neat resin counterpart, whereas a small enhancement in their moduli was achieved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

This article presents the study of melt compounding of polystyrene (PS) with various types of titanium dioxide (TiO2) nanoparticles and surfactants, using a corotating twin screw extruder with multiple screw element configurations. It was found that a properly designed high shear screw configuration and the copolymer of silicone, ethylene oxide, and propylene oxide-based surfactant produced the greatest degree of nanoparticle dispersion in PS/TiO2 nanocomposites, whereas a silane-based surfactant and silicon dioxide (SiO2) or aluminum oxide (Al2O3) coated TiO2 nanoparticles yielded nanocomposites with the least photocatalytic degradation effects and the best retention of tensile and impact properties. POLYM. COMPOS., 28:241–250, 2007. © 2007 Society of Plastic Engineers

A novel type of highly flexible and all-solid-state supercapacitor that uses cellulose nanofibril (CNF)/reduced graphene oxide (RGO)/carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4/poly(vinyl alcohol) (PVA) gel as the electrolyte was developed and is reported here. These flexible solid-state supercapacitors were fabricated without any binders, current collectors, or electroactive additives. Because of the porous structure of the CNF/RGO/CNT aerogel electrodes and the excellent electrolyte absorption properties of the CNFs present in the aerogel electrodes, the resulting flexible supercapacitors exhibited a high specific capacitance (i.e., 252 F g(-1) at a discharge current density of 0.5 A g(-1)) and a remarkable cycle stability (i.e., more than 99.5% of the capacitance was retained after 1000 charge-discharge cycles at a current density of 1 A g(-1)). Furthermore, the supercapacitors also showed extremely high areal capacitance, areal power density, and energy density (i.e., 216 mF cm(-2), 9.5 mW cm(-2), and 28.4 μWh cm(-2), respectively). In light of its excellent electrical performance, low cost, ease of large-scale manufacturing, and environmental friendliness, the CNF/RGO/CNT aerogel electrodes may have a promising application in the development of flexible energy-storage devices.

Three types of composites, namely, polylactide (PLA)/nanoclay, PLA/core–shell rubber, and PLA/nanoclay/core–shell rubber, were melt compounded via a corotating twin-screw extruder. The effects of two types of organically modified montmorillonite nanoclays (i.e., Cloisite®30B and 20A), two types of core (polybutylacrylate)–shell (polymethylmethacrylate) rubbers (i.e., Paraloid EXL2330 and EXL2314), and the combination of nanoclay and rubber on the mechanical and thermal properties of the composites were investigated. According to X-ray diffraction and transmission electron microscopy analyses, both types of PLA/5 wt% nanoclay composites had an intercalated morphology. In comparison with pure PLA, both types of PLA/5 wt% nanoclay composites had an increased modulus, similar impact strength, slightly reduced tensile strength, and significantly reduced strain at break. On the other hand, PLA/EXL2330 composites with a rubber loading level of 10 wt% or higher had a much higher impact strength and strain at break, but a lower modulus and strength when compared with pure PLA. The simultaneous addition of 5 wt% nanoclay (Cloisite®30B) and 20 wt% EXL2330 resulted in a PLA composite with a 134% increase in impact strength, a 6% increase in strain at break, a similar modulus, and a 28% reduction in tensile strength in comparison with pure PLA. POLYM. ENG. SCI. 46:1419–1427, 2006. © 2006 Society of Plastics Engineers

This paper reviews some of the recent developments of microcellular injection molding, which is capable of producing parts with excellent dimensional stability using lower injection pressure, shorter cycle time, and less material. Process conditions as well as nano/micro-fillers such as nanoclay and core–shell rubber have a strong influence on cell density and cell size, hence, the final material properties of the molded parts. The addition of nano/micro-fillers at optimum loading levels can generally facilitate the formation of microcellular plastics with higher cell density and smaller cell size leading to superior mechanical properties. The novel integration of a solid plastic surface with a microcellular plastic core via the co-injection molding technique has been investigated to achieve Class “A” surfaces and improved material performance. An improved mathematical model has been developed to simulate the cell growth behavior in the microcellular injection molding process.

The effects of submicron core-shell rubber (CSR) particles, nanoclay fillers, and molding parameters on the mechanical properties and cell structure of injection-molded microcellular polyamide-6 (PA6) composites were studied. The experimental results of PA6 nanocomposites with 5.0 and 7.5 wt% nanoclay loadings and of CSR-modified PA6 composites with 0.5 and 3.1 wt% CSR loadings were compared to their neat resin counterparts. This study found that nanoclay was more efficient in promoting a smaller cell size, larger cell density, and higher tensile strength for microcellular injection molding parts. A higher nanoclay loading led to more brittle behavior for microcellular parts. It was found that a proper amount of CSR particles could be added to the microcellular injection-molded PA6 to reduce the cell size, increase the cell density, and enhance the toughness of the molded part. However, CSR particles were less effective cell nucleation agents as compared to nanoclay for producing desirable cell structures, and a higher CSR loading was found to have diminishing effects on the process and on the properties of the parts. POLYM. ENG. SCI., 45:773–788, 2005. © 2005 Society of Plastics Engineers

This paper presents the effects of processing parameters and submicron core-shell rubber particle filler on the mechanical properties and cell morphology of microcellular injection molded polyamide-6 (PA-6) composites. Three types of materials are studied, namely, neat PA-6 resin, and 0.5 wt% and 3.1 wt% core-shell rubber polybutylacrylate-polymethylmethacrylate-filled PA-6 composites. This study shows that the addition of a small amount (0.5%) of core-shell rubber particles improved the ductility and impact strength of micro-cellular injection molded PA-6 samples. In comparison to the microcellular injection molded PA-6 polymer-clay nanocomposite, the samples with a small amount (0.5%) of core-shell rubber had much higher impact strength and ductility. The small addition of core-shell rubber also reduced cell size and increased cell density of the microcellular injection molded PA-6 parts, in comparison to their neat resin counterparts. On the other hand, at higher core-shell rubber loading, the cell size and density were found to be similar to that of the neat resin.

The effects of nanoclay addition into polyamide-6 (PA-6) neat resin and processing parameters on cell density and size in microcellular injection molded components are investigated. The analyses are performed on the sprue section of standard ASTM D 638-02 tensile bars molded based on a fractional four-factorial, three-level, L9 Taguchi design of experiments (DOE) with varying melt temperature, injection speed, super critical fluid (SCF) concentration, and shot size. It is found that the presence of nanoclay greatly reduced the cell size and increased the cell density when compared to neat resin processed under identical molding conditions. In addition, cell size distribution at the sprue center was, in general, the largest, gradually decreasing toward the skin for both the neat resin and the nanocomposite. Finally, in contrast to neat resin, in which shot size and injection speed were important to cell density and all molding parameters affected cell growth, the cell size and density for nanocomposite only depended strongly on shot size.

The crystallization behaviors of polyamide-6 (PA-6) and its nanocomposites undergoing the microcellular injection molding process are studied using Transmission Electron Microscopy (TEM), X-ray Diffractometer (XRD), Polarized Optical Microscopy (POM), and Differential Scanning Calorimetry (DSC). The relationships among the morphology, the mechanical property of the molded parts, and the crystallization behavior are investigated. With the addition of nanoclays in microcellular injection molded parts, the growth of the γ-form crystal is suppressed and the formation of γ-form crystals is promoted. Both nanoclay and dissolved gas have a big influence on PA-6 crystalline structures. The existence of nanoclay increases the initial crystallization rate. But with extra addition of nanoclays in the polymer matrix, the increase of crystallization rate is reduced. Microcellular injection molded nanocomposites with proper amount of nanoclays possess the maximum crystallization activation energy and produce a finer and denser microcell structure which leads to better mechanical properties.

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The microcellular nanocomposite processing was performed on an injection-molding machine equipped with a commercially available supercritical fluid (SCF) system. The molded samples produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, Dynamic Mechanical Analysis (DMA), and Scanning Electron Microscope (SEM) analyses. Molding conditions and nano-clays have been found to have profound effects on the cell structures and mechanical properties of polyamide-6 (PA-6) base resin and nanocomposite samples. The results show that microcellular nanocomposite samples exhibit smaller cell size and uniform cell distribution as well as higher tensile strength compared to the corresponding base PA-6 microcellular samples. Among the molding parameters studied, shot size has the most significant effect on cell size, cell density, and tensile strength. Fractographic study reveals evidence of different modes of failure and different regions of fractured structure depending on the molding conditions. Polym. Eng. Sci. 44:673–686, 2004. © 2004 Society of Plastics Engineers.

The effects of adding nanoclay to polyamide-6 (PA-6) neat resin, and the effects of processing parameters on cell density and size in microcellular injection-molded components were investigated. In addition, the crystal sizes, structures, and orientation were analyzed with the use of x-ray diffraction (XRD) and a polarized optical microscope. The standard ASTM D 638-02 tensile bars for the analyses were molded according to a fractional four-factor, three-level, L9 Taguchi design of experiment (DOE) with varying melt temperature, injection speed, supercritical fluid (SCF) concentration, and shot size. It was found that the presence of montmorillonite (MMT) nanoclay greatly reduced the size of the cells and crystals, but increased their density in comparison with neat resin processed under identical molding conditions. In addition, at the sprue section downstream of the machine nozzle, cell size gradually decreased from the part center toward the skin for both the neat resin and the nanocomposite. It was also found that shot size was the most important processing parameter for both the neat resin and nanocomposite in affecting cell density and size in microcellular injection molding components. Weakly preferred crystal orientations were observed on the surface of microcellular injection-molded PA-6/MMT tensile bars. Finally, the addition of nanoclay in PA-6 neat resin facilitated the formation of γ-phase crystals in the molded components. Polym. Eng. Sci. 45:52–61, 2005. © 2004 Society of Plastics Engineers.

This paper presents the effects of process conditions and nano-clay fillers on the microstructure (namely, size, density, and distribution of microcells within samples) and the resulting mechanical properties of microcellular injection molded polyamide-6 (PA-6) nanocomposite and its neat-resin counterpart. Based on the design of experiments (DOE) matrices, samples were molded at various supercritical fluid (SCF) levels, melt temperatures, shot sizes, melt plastication pressures (MPP), and injection speeds. These samples were then subjected to scanning electron microscope (SEM) analysis, tensile testing, and impact testing. For both materials, the microstructure and the mechanical properties of the molded samples were found to be dependent on the process conditions and presence of nano-clay, which could serve as microcell nucleating agent. At higher weight reductions, the nanocomposite samples exhibit much smaller microcells and higher cell densities than those obtained in the neat-resin samples. The SEM micrographs reveal noticeable differences in microcell surface roughness between the nanocomposite and the neat resin. A statistical design analysis was used to identify the optimal process conditions that would result in desirable cell size and density and, thus, better mechanical properties. For example, the highest tensile strengths have been observed at the highest levels of shot size, MPP, injection speed, and SCF level, and at the lowest level of melt temperature.