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Epoxy matrix nanocomposites were prepared by diglycidyl ether of bisphenol A (DGEBA) modified with epoxide polyurethane (EPU) containing oxazonegroup and reinforced by low concentrations of octaaminophenyl polyhedral oligomeric silsesquioxane (OAPOSS). The thermal, mechanical, and thermomechanical properties of as-prepared hybrid nanocomposites were studied. The results demonstrate that the thermal stability, tensile strength, glass transition temperature, and storage modulus of epoxy polymer/EPU blends are all significantly improved with OAPOSS as an reinforcement. The inclusion of EPU in the epoxy polymer helps improve the toughness of the matrix, providing higher impact strength, and higher elongation at break. Tribological testing shows that the wear rate of the hybrid nanocomposite is reduced by more than 80% at 0.1 wt% OAPOSS compared with pure epoxyEPU, while the friction coefficient is nearly unchanged. SEM-EDS analysis of worn scar indicates that the wear mechanism of OAPOSS incorporated hybrid composites is the coexistence of abrasive wear and adhesive wear. The improved properties are due to the uniform dispersion of OAPOSS in the epoxy-EPU matrix and network formation by cross-linking and chemical bonds from OAPOSS reacted with epoxy-EPU matrix. KEYWORDS epoxide-polyurethane, epoxy polymer nanocomposites, polyhedral oligomeric silsesquioxane, SEM-EDS, thermal behaviors, tribological properties, 1 | INTRODUCTION Polymer nanocomposites are well known for high strength to weight ratios and flexibility in material designing. Epoxy polymers (EPs) are widely used as adhesives, coatings, and advanced [...]

Supercontraction fiber with shrinkage ratio as high as eight times is processed from simple polymer blending and melt spinning. Specifically, polycaprolactone and ethyleneoctene block copolymer blends are made and then processed into fibers with a two-step sequence of melt extrusion and room-temperature drawing. The morphological properties, mechanical properties, rheological behavior, thermal properties, and shrinking ability of the blend fiber are characterized. The scanning electron microscope images of the blends indicate two types of structure: Cocontinuous structure and matrix-droplet structure. Fiber made from the Cocontinuous blend has the supercontraction ability, while fiber from the matrix-droplet blend does not. Additional hot drawing of the fiber at 50[degrees] C is found to be helpful for improving the mechanical properties, shrinking ratio, and shrinking stress. Cyclic tensile testing was also conducted and the results show that the supercontraction fiber may be used repeatedly for multiple times., INTRODUCTION Supercontraction is well known in some natural fibers. It describes the phenomenon of a much larger shrinkage in the longitudinal dimension of the fiber than that occurs in the [...]

A critical issue facing mankind is how to effectively recycle plastic grocery bags. Currently, the most proven practice for bag recycling is to create numerous returning sites throughout the nation. However, the success is compromised by the voluntary nature of such activities. In this work, we investigate an alternative approach to bag returning, by diverting recycling activities directly to consumers or end users at home. Specifically, a simple process for converting waste bags into high-strength fibers and yarns is designed and tested in an experimental feasibility study. The results from tensile testing and thermal analysis demonstrate that by a combined process sequence of cutting, knotting, twisting, hot drawing, and heat setting, high-strength polyethylene yarns with mechanical properties comparable to those of melt-spun polyethylene fibers can be produced. Without the involvement of melt processing, yarns made of a waste high-density polyethylene grocery bag material were hot drawn and heat set to achieve a tensile strength of 330 MPa. Yarns with such ternacity are expected to find numerous applications in textile, flooring, and leisure products. This may open up a new paradigm in plastic bags recycling and allow part of the recycling burden to be shifted to local residential communities., INTRODUCTION It is estimated that about a trillion plastic bags are consumed every year worldwide [1, 2]. In United States alone, about 100 billion plastic bags are consumed yearly [2]. [...]

A unique methodology employing a 'nearly co-continuous morphology' for processing immiscible polymers into strong fiber is presented, and an immiscible polypropylene/polystyrene (PP/PS) blend is used as a model system to demonstrate the effectiveness of this methodology. The 'nearly co-continuous morphology' is easier to obtain than the fully co-continuous structure, and yet, it provides an engineering solution to the production of strong fiber from an immiscible polymer blend. In addition, a process different from traditional melt spinning is used to prepare fiber with good mechanical properties. Traditional melt spinning involves large jet stretch and therefore introduces large interfacial orientation but little molecular orientation in polymer blends. To address this issue, the PP/PS blend is spun with nearly zero jet stretch and after solidification undergoes hot drawing at temperature close to the glass transition temperature of PS. This process sequence imparts a large degree of molecular orientation to the PP phase and produces a strong fiber. The proposed methodology can be extended to other blend systems and provides a potential route for directly recycling commingled polymer waste without preseparation or compatibilization., INTRODUCTION Millions of tons of plastics are produced and consumed every year but only a small part of them are recycled. Many plastics end up in landfills or become pollutants [...]

Gel spinning of UHMWPE fibers using low molecular weight polybutene (PB) as a new spin solvent was investigated. A 98/2 wt% PB/UHMWPE gel exhibits a melting temperature around 115°C and shows large-scale phase separation upon cooling the solution to room temperature. The resulting precursor fiber from this gel was hot-drawn to a ratio of 120, yielding a fiber with tensile strength of 4 GPa and Young's modulus of over 150 GPa. Wide-angle X-ray diffraction indicates good molecular orientation along the fiber axis. The results also demonstrate the potential to further improve the mechanical properties. With respect to the gel spinning industry, this new solvent has a number of advantages over paraffin oil and decahydronaphthalene, and holds a promise of greatly improving the process efficiency., INTRODUCTION High performance polyethylene (PE) fibers continue to replace conventional materials in many military and civilian applications such as composites, ropes, and textiles. The success of these fibers owes largely [...]

Polypropylene (PP) with high melt flow index (MFI) or low molecular weight, although desired in melt spinning for enhanced productivity, is difficult to be spun into high-strength fiber using the standard process where extensive jet stretching is applied. In this work, a processing route involving minimal jet stretch has been explored. A two-stage hot drawing procedure in the solid state was found to be suitable for producing high-strength fiber from low-molecular-weight PP with an ultrahigh MFI of 115 g/10 min. Fibers produced achieve a maximum tensile strength and Young's modulus of approximately 600 MPa and 12 GPa, respectively. The melt temperature of the fiber reached 170.8°C, approximately 5°C higher than that of the original resin. Wide-angle X-ray diffraction (WAXD) study shows that the stable α-monoclinic crystalline structure is developed during the drawing process. A well-oriented crystalline structure along the fiber axis is generated, having a crystalline orientation factor as high as 0.84. POLYM. ENG. SCI., 56:233-239, 2016. [C] 2015 Society of Plastics Engineers, INTRODUCTION Melt spinning is a common process to produce high-tenacity polypropylene (PP) fiber, one of the leading commercial fibers in the field of industrial textiles. Efforts to make strong PP [...]

In this work, a microwave expansion process to produce thermoset-matrix syntactic foam containing thermoplastic foam beads was designed and developed. Expandable polystyrene (EPS) microspheres and epoxy resin were chosen as a model material system. This process is featured with a capability to effectively expand EPS microspheres in syntactic foam with high EPS loading. The resin viscosity and specific microwave energy are found to be the two primary control parameters determining the process window. Mechanical characterization showed that the specific flexural strength and modulus of the syntactic foam are similar to those of the neat epoxy. By comparison, the flexural moduli over density squared or cubed of the foam are much higher, especially at high EPS loadings, than those of the neat resin. The foamed EPS microspheres can also effectively toughen the syntactic foam, preventing propagation of cracks. Furthermore, the microwave expansion process was found to be capable of molding syntactic foam parts of relatively sophisticated geometry with smooth surfaces., INTRODUCTION Syntactic foam is a special kind of gas-filled polymeric materials in which microballoons or foamed microspheres are embedded uniformly in a polymer matrix designated as a binder [1]. Different [...]

Composite polystyrene foam with a honeycomb-like barrier structure was processed from an expandable aqueous suspension. Optical observations confirmed the formation of such a unique structure that encapsulates each expanded polystyrene microsphere in the resulting foam. The suspension viscosity was found to highly influence the foam morphology. Results from mechanical tests showed that the existence of the barrier structure can considerably improve the mechanical performance of the composite foam. Fire retardation tests demonstrated that the barrier structure can effectively stop the fire path into the foam, suppress toxic smoke generation, and maintain structural integrity, leading to improved fire resistance in comparison with the neat polystyrene foam., INTRODUCTION Expandable polystyrene (EPS) is the raw material used for molding foamed polystyrene products. It is manufactured into small-diameter polystyrene microspheres containing physical blowing agents, usually pentane or butane. When [...]

A new twist-gel spinning process for ultrahigh molecular weight polyethylene fibers is demonstrated which significantly increases the extraction rate of nonvolatile spin solvent while simultaneously reducing the consumption of extraction solvent by more than 75%. Applying twist to the gel fiber enables it to be directly hot-drawn, allowing conventional solvent extraction to proceed significantly faster. While solvent extraction effectiveness is largely enhanced, the new process does not show reduced fiber properties. The tensile strength, Young's modulus, surface morphology, and geometry are relatively unaffected when compared to fibers produced using the conventional gel-spinning process. The new twist-gel spinning process is expected to improve the processing efficiency of gel-spun high-strength fibers, promoting broad expansion of these high performance fibers into applications that were previously prohibitive due to extremely slow production., INTRODUCTION Gel-spun UHMWPE (ultrahigh molecular weight polyethylene) fiber exhibits remarkable tensile properties [1, 2]; however, the relatively complex processing involved in its production leads to costs almost ten times more [...]

A new method for fast solvent removal in gel spinning was investigated. Instead of solvent evaporation or coagulation as conventionally used, the new method involves mechanically twisting the gel-fiber along the fiber axis. By removing the majority of solvent in the gel-fiber by mechanical twisting not only the emission of solvent vapor and the production of waste solvent mixture or coagulation byproducts are minimized but also the fiber production rate is significantly increased. The new solvent removal method was demonstrated through gel spinning of high-strength ultrahigh-molecular-weight polyethylene fibers using both volatile and nonvolatile spin solvents. Approximately 90% of the spin solvent was removed by a single-step twisting process and the resulting fiber retained the high mechanical properties conventionally obtained. A mechanistic model was developed for estimating the solvent removal as a function of twisting. With respect to the gel spinning industry, the new solvent removal method holds a promise of simplifying the solvent removal and recovery steps and improving the production rate, leading to more efficient and effective gel spinning processes., INTRODUCTION The gel spinning process for ultrahigh-molecular-weight polyethylene (UHMWPE) fiber, beginning in the late 1970s through the work of Smith et al. [1, 2], has grown into several commercial processes [...]

This article describes a new gel-spinning process for making high-strength polyethylene oxide) (PEO) fibers. The PEO gel-spinning process was enabled through an oligomer/polymer blend in place of conventional organic solvents, and the gelation and solvent-like properties were investigated. A 92/8 wt% polyethylene glycol)/PEO gel exhibited a melting temperature around 45°C and was highly stretchable at room temperature. Some salient features of a gel-spun PEO fiber with a draw ratio of 60 are tensile strength at break = 0.66 ± 0.04 GPa, Young's modulus =4.3 ± 0.1 GPa, and a toughness corresponding to 117 MJ/[m.sup.3]. These numbers are significantly higher than those previously reported. Wide-angle x-ray diffraction of the high-strength fibers showed good molecular orientation along the fiber direction. The results also demonstrate the potential of further improvement of mechanical properties. POLYM. ENG. SCI., 54:2839-2847, 2014. © 2014 Society of Plastics Engineers, INTRODUCTION Gel-fiber spinning has been successfully applied to several polymers including polyethylene (PE), polypropylene (PP), and poly(vinyl alcohol) (PVA), typically generating fibers significantly stronger and stiffer than their melt or [...]

A microsphere templating process was recently developed for fabrication of open-cell porous elastomer. The material contained a unique cocontinuous structure having micropores interconnected by microchannels. In this work, a follow-up study was conducted to investigate the mechanical behavior of such porous materials. Polysiloxane was chosen as a model material. The deformation characteristics and mechanical properties of the porous elastomer under tension and compression were then studied. For both tensile and compressive tests, the mechanical properties measured were found to largely deviate from those calculated by the additive rule assuming affine deformation. This nonaffine mechanics was further verified by microscopic observations. Cyclic loading and unloading tests were also performed to study the hysteresis of the material. In comparison with the solid elastomer, the hysteresis of the porous elastomer was considerably higher and more sensitive to the strain rate. An attempt was further made to fit the stress-strain curve using existing hyperelastic models, and the results showed that the Arruda-Boyce model, in general, fit both the solid and porous polysiloxane very well., INTRODUCTION There has been a growing interest in developing interconnected porous elastomers, primarily driven by many emerging applications in the biomedical field [1-7]. Currently, salt leaching is the most widely [...]

In conventional hot embossing, a thermoplastic polymer undergoes phase transitions in liquid, semi-solid, and solid states through cyclic heating and cooling. This paper, in contrast, describes the development of a constant-temperature embossing process and compares its characteristics against standard hot embossing. The new process utilizes the crystallizing nature of supercooled polymer films to obtain the necessary phase transitions. By softening and crystallizing the supercooled polymer at the same temperature, the embossing and solidification stages can be carried out isothermally without a cooling step. PET, due to its relatively slow crystallizing kinetics, was chosen as a model material for this study. The embossed films with microgroove patterns of different sizes and aspect ratios were characterized for their replication fidelity and accuracy. For supercooled PET films, constant-temperature embossing with high replication quality and acceptable demolding characteristics was achieved in a large processing temperature window between [T.sub.g] and [T.sub.m] of PET. A parametric process study involving changes of the embossing temperature and embossing time was conducted, and the results indicated that the optimal process parameters for constant-temperature embossing can be derived from the crystallization kinetics of the polymer. The removal of thermal cycling is a major advantage of constant-temperature embossing over conventional hot embossing and represents an important process characteristic desired in industrial production. POLYM. ENG. SCI., 54:1100-1112, 2014. © 2013 Society of Plastics Engineers, INTRODUCTION Significant developments in the field of microreplication have facilitated production of miniaturized products with finer details and superior accuracy. Hot embossing and injection molding are two different types of [...]

This two-article sequence on rubber-assisted embossing was aimed to understand the basic mechanisms affecting the pattern uniformity and replicability and to determine a process window for achieving uniform patterning and faithful replication. In Part I, the effects of major process and material parameters were identified and studied, and strategies for successful hot embossing with rubber as a pressure medium were proposed. In Part II, the rubber-assisted embossing process was analyzed considering the unique rheological behavior of the materials involved to develop useful predictive capabilities for this new process. Specifically, a finite-strain hyperelastic formulation was used for simulating the isothermal embossing stage, and a generalized Maxwell model was used to study the stress relaxation during the holding stage and to predict the elastic recovery after demolding. The rheological properties obtained in Part I were fitted to the constitutive models and implemented in the simulation procedures. The simulation results agreed with the major findings in the experimental work and provided a more quantitative insight into the process. POLYM. ENG. SCI., 51:601-608, 2011. [C]2011 Society of Plastics Engineers, INTRODUCTION In rubber-assisted embossing, a thin polymer film is bent and stretched to form a microshell pattern. This deformation process is similar to that experienced in conventional thermoforming where a [...]

In rubber-assisted hot embossing, a softened thin thermoplastic film is pressurized between a hard mold surface and a rubber pad. The rubber pad, as a soft counter-tool, deforms conformably to the hard mold surface, allowing feature transfer from the hard surface and formation of shell-type structures on the polymer film. This two-article sequence was aimed to understand the basic mechanisms affecting the pattern uniformity and replication in rubber-assisted hot embossing. In Part I, a series of rubber-assisted embossing experiments involving parametric studies of the effects of different processing conditions, as well as material selections, on the pattern thickness uniformity and replicated pattern height were conducted. The difference in film thickness uniformity in different experiments was explained using the mechanical and rheological behavior of the polymer film and the rubber counter-tool under different processing conditions. Based on the experimental results, strategies for determining a feasible process window for achieving uniform shell patterning by rubber-assisted embossing were proposed. POLYM. ENG. SCI., 51:592-600, 2011. [C]2011 Society of Plastics Engineers, INTRODUCTION One of the most widely used techniques for conversion of polymeric materials into useful microdevices is hot embossing (1-3). It is a process variant of compression molding, particularly designed [...]

Processing-related properties of a polypropylene (PP)/silicone oil blend were investigated. It was found that an addition of a small amount (~2 wt%) of silicone oil, a low molecular weight linear poly(dimethyl siloxane) (PDMS), drastically changed the rheological properties of PP. The PDMS seemed to work both as an internal lubricant and an external lubricant in the blend system. In particular, the apparent viscosity of the blend in capillary rheometry was approximately 10 times lower than that of virgin PP. The local minima in the viscosity versus shear rate curve in capillary rheometry and the gap-dependency of viscosity in parallel-plate rheometry implied the existence of a slip wall condition, caused by the formation of a thin lubricant layer at die walls. Thermal analyses and mechanical tests showed that the thermal and mechanical properties of the blend were nearly unaffected by the minor addition of silicone oil. The blend was tested in a profile extrusion process, and a significant reduction in die swell and profile distortion was achieved. The jet stretchability or spinnability in fiber spinning was also greatly improved with the minor addition of silicone oil. POLYM. ENG. SCI., 50:1340-1349, 2010. [C] 2010 Society of Plastics Engineers, INTRODUCTION Polymers used in melt processing typically have a high molecular weight. For example, the molecular weight of commercially used polyolefins, such as polyethylene and polypropylene (PP), often exceeds 100,000 [...]

The hot embossing process has so far been developed mainly for replication of surface structures on thermoplastic substrates. Because of the lack of a through-thickness action, fabrication of discrete microparts such as microgears is considered difficult. In this study, embossing molds having multiple microcavities were used in a through-thickness embossing process with a rubber-assisted ejection mechanism. Microparts made of HDPE and ABS with each part weighing approximately 1 and 1.4 mg, respectively, were produced. When in the mold, embossed microparts were intermittently connected to each other through thin residual films of a thickness approximately 20 µm. The residual films were detached from the microparts during a rubber-assisted ejection stage. Because no resin delivery paths, e.g., runners and gates, are needed for microcavities on the multicavity embossing mold, this micropart fabrication process could replace micro injection molding in many applications. POLYM. ENG. SCI., 49:1894-1901, 2009. [C] 2009 Society of Plastics Engineers, INTRODUCTION The standard hot embossing process is designed for fabricating surface features on polymer substrates (1), (2), The substrate is relatively thick as compared with the feature size. During the [...]

The standard embossing process is limited to the fabrication of surface structures on relatively large polymer substrates. To overcome this limitation, a hybrid punching and embossing process was investigated for through-thickness embossing of three-dimensional parts. The embossing tool included a punching head and to-be-replicated features in the socket behind the punching head. The built-in punching head facilitated a through-thickness action and provided a closed-die environment for embossing pressure buildup. The method was used to emboss multichannel millimeter waveguides which requires uniform edges and accurate dimensions. With a tool temperature of 140°C, an embossing time of 3 min and a total cycle time of 7 min, discrete 4-channel waveguides were successfully embossed from a room-temperature ABS substrate. A computer model was established to study the flow behavior during through-thickness embossing. It was found that nonisothermal embossing conditions help confine the polymer in the cavity and reduce the outflow into the surrounding region, thus achieving complete fill of the cavity. POLYM. ENG. SCI., 47:2075-2084, 2007. © 2007 Society of Plastics Engineers, INTRODUCTION The standard hot embossing process is designed for imprinting surface features onto polymer substrates [1, 2]. The substrate is relatively thick as compared with the feature size. During the [...]

An embossing strategy involving a hot station and a cold station for sequentially heating and cooling the embossing tool was investigated to reduce cycle times in hot embossing polymer microstructures. Experimental studies showed that aluminum stamps with a thickness of 1.4 mm can be rapidly heated from room temperature to 200°C in 3 s using contact heating against a hot station at 250°C. Microchannels and microlenses were successfully embossed onto high-density polyethylene and acrylonitrile-butadiene-styrene substrates using a heating time less than 3 s and a total cycle time around 10 s. The two-station embossing process for the microlens was also numerically studied. The simulated filling behavior agreed with the experimental observation and the predicted thermal and deformation history of the polymer offered a good explanation on the experimentally observed process characteristics. POLYM. ENG. SCI., 47:530-539, 2007. © 2007 Society of Plastics Engineers, INTRODUCTION The hot embossing process involves several sequential stages. First, a preheated thermoplastic film is placed between two heated mold platens heated above the polymer softening temperature (glass transition temperature [...]

Thermal cycling of molds is frequently desired in thermoplastic processing. Thermal cycling of the entire mold with a large mass, however, requires an exceedingly long cycle time. A processing strategy for mold rapid heating and cooling, involving a thin-shell mold and two thermal stations (one hot and one cold), was investigated. Because of its low thermal mass, the shell mold can be rapidly heated and cooled through heat conduction by selectively contacting with the two stations. Numerical simulations were performed to study the effect of different design parameters, including thermal contact resistance, shell material, and shell thickness, on the thermal response at the mold surface. Experimental studies showed aluminum shell molds with a thickness of 1.4 mm can be rapidly heated from room temperature to 200[degrees]C in about 3 s using a hot station at 250[degrees]C. The method was used for thermal cycling of embossing tools. Surface micro-features can be rapidly transferred from thin metallic stamps to polymer substrates with cycle times less than 10 s. [DOI: 10.1115/1.2335855] Keywords: thermoplastic processing, rapid heating, embossing, welding, contact heating

An approach of using slowly crystallizing polymers to form single-polymer composites (SPCs) was investigated. The method was demonstrated using poly(ethylene terephthalate) (PET) as a model system, with which two distinct physical forms, namely, amorphous PET films and highly crystalline PET fibers can be readily obtained. Because of the large difference between the rubbery softening temperature of the amorphous phase and the melting temperature of the crystalline phase, the new process is characterized by its wide process window and enhanced manufacturability. The heating temperature and holding time were found to play a profound role in influencing the properties of the SPC. Excellent fiber-matrix interfacial adhesion was obtained at heating temperature 180°C and holding time 10 s. The results also indicated that the heating rate plays a significant role in affecting the fusion and adhesion of the composite. With reduced heating rates, the fusion and adhesion properties are rapidly deteriorated. POLYM. ENG. SCI., 46: 1223-1230, 2006. © 2006 Society of Plastics Engineers, INTRODUCTION The original concept of a single-polymer composite (SPC), a composite with matrix and reinforcement from the same polymer, was presented by Capiati and Porter [1] three decades ago. The [...]

High-frequency proximity heating was used to rapidly heat injection molds. The principle is based on the proximity effect between a pair of mold inserts facing each other with a small gap and forming a high-frequency electric loop. Because of the proximity effect, the high-frequency current will flow at the inner surfaces of the facing pair, thus selectively heating the mold surface. With this method, the electrical insulation layer beneath the mold surface can be eliminated, resulting in a mold insert made of a single metal. A mold with a cavity of 25 x 50 [mm.sup.2] was constructed with careful design on its electrical, structural, and thermal performance. Air pockets with reinforcing ribs were embedded right beneath the mold surface for enhancing the heating performance. The resulting mold cavity can be rapidly heated from room temperature to about 240°C in 5 s with an apparent heating power of 93 W/[cm.sup.2]. The new mold heating method was applied to thin-wall molding and micromolding, and in all testing cases, short cycle times less than a minute were achieved. POLYM. ENG. SCI., 46:938-945, 2006. © 2006 Society of Plastics Engineers, INTRODUCTION It is a common practice in thermoplastic injection molding that the mold temperature stays at a preset constant temperature well below the softening temperature of the thermoplastic polymer. Auxiliary [...]

A numerical simulation of the hot embossing process with nonisothermal embossing conditions was carried out to observe the flow pattern of poly(methyl methacrylate) into microcavities. The microcavity was isomorphically downsized. The ratio of the cavity width over the cavity thickness was maintained constant at 8:1 throughout the analysis, while the cavity thickness varied from 200 µm to 0.5 µm. It was found that as the microcavity was downsized, the filling mechanism varied. For larger cavity thicknesses (e.g., 100 µm), the polymer flow climbed along the wall of the heated die and was then compressed downward and squeezed outward. In contrast, for a smaller cavity thickness (e.g., 5 µm), the flow was uniform and the wall-climbing flow was absent. This size effect was correlated with the uniformity (UNF) of the temperature distribution of the polymer substrate during the embossing process. For larger cavity thicknesses, the high temperature zone was localized in the vicinity of the die wall, and consequently localized wall-climbing flow occurred. The size effect in nonisothermal embossing was also studied experimentally, and localized flow was observed for larger cavities but not for smaller cavities. POLYM. ENG. SCI., 45:652-660, 2005. © 2005 Society of Plastics Engineers, INTRODUCTION Polymer microfabrication methods are becoming increasingly important as low-cost alternatives to silicon- or glass-based microfabrication technologies. The hot embossing technique [1] is a flexible, cost-effective microfabrication method for polymer [...]

Miniaturization of injection molded parts causes changes in the relative contribution of relevant design and process parameters. As a result, scaling-related size effects occur Size effects can be either of the first order or of the second order. First-order size effects can be predicted using standard modeling, while second order ones cannot. This paper deals' with first-order size effects encountered in injection molding miniaturized parts. Through the scaling analysis of the heat transfer and flow process in injection molding, the size effects on the change of molding characteristics including viscous heating, freezing time, capillary force effect, and moldability were identified. Strategies were consequently proposed to alleviate or eliminate the scaling-related molding difficulties in molding ultrathin-wall parts and microparts. Particularly, a scalable filling process was presented, with experimental verification. Keywords: Miniaturization, Injection Molding, Scaling Analysis, Size Effect