The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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Contour Laser Transmission Welding - How Fast is Fast Enough
During contour laser transmission welding (LTW), energy is absorbed by the laser-absorbing (ie black) material and immediately begins to redistribute itself by conduction inside the thermoplastic material. If the time over which this energy is deposited is quite long (corresponding to either a low scan speed or very long laser beam length), significant heat flow by conduction can occur before all of the laser energy has been deposited at a given point. For this reason, one cannot perform contour LTW with a classroom laser-pointer – the low power would require a low scan speed to deposit the requisite energy and, during that long time, most of the energy would be lost to the surroundings by conduction and melting would not occur. Conversely, if the time over which this energy is deposited is quite short (corresponding to either a high scan speed or very short laser beam length), very little conduction occurs during the heating period. This allows some simplification to the modeling process such as that proposed by Chen . The question addressed by this paper is, for a given set of material and laser parameters, at what laser scan speed can the effect of thermal conduction during heating be largely ignored. The paper shows that the critical speed is related to the material’s thermal diffusivity, absorption coefficient and the scattered laser beam length.
Characterization of Rice Husks for Potential Development of Biopolymers
Rice husk is a major biomass that is abundant, renewable and thus is promising material for the development of biodegradable polymers. The physical structure of rice husks between two different varieties of long grain rice has been evaluated in this study. The results show that the wall of the rice husk consists of 3 different layers with full and hollow fibers with different orientations. The fibers consist predominantly of cellulose and hemicellulose. Rice husk also contains about 10% moisture and about 20- 25% silica. The different varieties of rice husk have a similar structure, but different thicknesses of various layer and different diameters for the fibers. Silica is concentrated mostly in the outer layer and is the main reason why rice husks need to be modified before they can be used to develop biodegradable polymers or employed as reinforcing agents in other polymers.
Ecofriendly Plastic with Incoporation of Lignin
The University of Wisconsin Platteville, gave a research grant to test and experiment with organic lignin from American Science and Technology (AST) in plastic. The goal is to incorporate a true bond of lignin with plastic, in particular polypropylene, to create a desired set of properties for the customer. A series of tests will be used to examine the compound for these properties, and fine tune the processing parameters. Lignin is known to be found in the second cell wall of most plant life, some algae, as well as trees. It is one of the most common organic polymers found on earth. There is approximately 1.1 million metric tons of lignin used today in various applications. It will be laser cut for tensile testing, notched izod, spectroscopy, weather testing, heat deformation testing, and others. The test data will be analyzed and submitted to the company. This will be a new product that will be used to cut down the cost of production, become the new ecofriendly alternative, and change the way the plastic foot print is viewed in the world today.
Effect of Rice Flour Filler on Heat Seal Strength for Sustainable Designed Sealant Film
The packaging materials are spoiled in a short cycle. An environment packaging materials are demanded. The economic cost is one of problems to substitute general plastics for bio-resource sustainable plastics. In this study the potential of rice flour as compounding filler for sealant polymer was examined. Poly(butylene succinate)(PBS) / rice flour composite biodegradable film was processed directly by twin-screw extruder equipped with T-die. Heat seal property of the biodegradable film was investigated. As compounding filler material, the potential of rice flour on heat seal property was studied. At 100 ºC of heat seal temperature, the PBS / rice flour composite film showed high heat seal strength comparing with neat PBS film. By scanning electron microscopy observation, bled out rice flour grains at film surface affected heat seal property. The PBS / rice flour composite film could keep more than 80% tensile strength comparing with neat PBS. However heat seal strength for HDPE / rice flour composite film dropped. To attain high seal strength it needed longer dwell time. The compounded rice flour prevented heat seal property for HDPE. The exposed rice flour particles worked effectively for PBS / rice flour composite film.
A New Method for Synthesis of Micron-Sized Polyamide 12 Microspheres via Phase Inversion Mechanism
Micron-sized polyamide 12 (PA12) microspheres were firstly synthesized through phase-inversion PA12/PS blends via phase inversion mechanism. The resulting PA12 microspheres are regular sphericity, with volume-average diameter about 19.7 microns and narrow size distribution (2.5), as confirmed by scanning electron microscopy (SEM) and Laser diffraction size Analyzer. Furthermore, the study on the PA12/PS blends confirmed that the morphology of PA12 microspheres are closely related to the content of PS in the blends, which indicated that the formation of the PA12 microspheres in the PA12/PS blends can be elucidated via a phase inversion mechanism.
The Fracture Mechanism of Polyamide 6/EPDM-M/Nano-Caco3 Ternary Composites with 'Sandbag' Structure
The fracture behavior of Polyamide 6 (PA6)/maleated mixed with unmaleated ethylene–propylene–diene rubber (EPDM-M)/ nano-calcium carbonate (nano-CaCO3) prepared by two step was studied. The fracture energy was studied by a single-edge notch (SEN) tensile test as function of test speed. The morphologies of impact fracture and tensile deformation processes were investigated by scanning electron microscope (SEM). The result shows that ternary composites with “sandbag” structure has higher fracture energy at high test speed, compared to pure PA6. The research of morphologies during different tensile deformation processes illuminates that the sandbag" structure is more effective for resisting the crack propagation compared to the crack initiation which exhibits high crack propagation energy (CPE) but low crack initiation energy (CIE)."
Deterioration Mechanistic Evaluation of PET Film
In recent years, the solar photovoltaic system has been attracted rising attention as an important power source in the viewpoint of environmental problems and other global issues. However, there are some problems in terms of durability of the each part. The back-sheet consisted of PET multi-layer films plays an important role to prevent moisture from outside into the main-board of the solar photovoltaic system. It is very important to investigate the durability of the back-sheet in order to maintain the usage of this system. In this research, we tried to evaluate the mechanical properties of PET films by applying the accelerated deterioration test. The durability was discussed on the basis of the results of the tensile test, the FT-IR measurement, and the SEM observation.
Reforming useful plastics products into solid-shape energy fuels
Diversion of waste streams, such as plastics, woods, and papers, from municipal landfill and extraction of useful products is an area of increasing interest across the country, especially in densely populated areas. One promising technology for recycling rubbish is to burn the high energy content components in standard coal boilers. This research seeks to reform wastes into block shapes that are compatible with typical coal combustion processes. In order to comply with the standards of coal-fired power plants, the feedstock must be mechanically robust, moisture resistant, and retain high fuel value. Two different type of waste stream, one based on household waste with high papers content, and the other based on construction waste with a significant wood fraction, were processed using a compression molding technique. The resulting mechanical properties, moisture absorption, and generation of energy from burning were investigated. The effects of solid waste particle size, compression pressure and temperature were studied to identify the optimal processing conditions. The feed-stream was augmented with recyclable plastics such as polystyrene and poly (ethylene terephthalate) to enhance the binding attraction for easy transport with improved mechanical properties, and the hardness of the composites was probed for the stability of solid fuels. Water uptake tests were also carried out for prepared samples to examine the durability of samples under humid conditions. Lastly, burning tests were performed to calculate the calorific value of the different samples resulting from the increased plastic contents. This research will contribute to alleviate the environmental problems related to landfill space, while producing an alternative fuel.
The Crystallization behavior of saolid and microcellular injection molded polypropylene and its calcium carbonate composites using carbon dioxide as a physical blowing agent
This work aimed to investigate the crystallization behavior of microcellular injection molded polypropylene (PP)/nano calcium carbonate (nano-CaCO3) composites. The effects of processing conditions, such as injection speed, mold temperature, and CO2 concentration as well as the filler concentration, on the crystal form, crystal orientation, and crystallinity were studied using 2D-wide-angle X-ray diffractometer (2D-WXRD) and differential scanning calorimeter (DSC). The ?-form crystal was found in the surface layer of injection molded samples under high injection and mold temperature, due to the high shear stress. The addition of nano-CaCO3 filler promoted the formation of ?-form crystal while the foaming process inhabited its formation. The orientation degree calculated from XRD images by Hermans function showed a high value in the surface layer and it decreased as the distance from the surface increases. Meanwhile, the orientation degree reduced with foaming and the addition of filler, as both the bubbles and fillers disturbed the orientation of molecular chains. The degree of crystallinity of samples was higher in the surface layer and increased with foaming. However, the degree of crystallinity reduced with the addition of fillers and showed no dependence on injection speed and mold temperature.
The Crystalline Behaviors and Thermal Properties Study of Polyamide 46/Graphene Oxide Nanocomposites
Polyamide 46 (PA 46)/graphene oxide (GO) nanocomposites were successfully prepared using a solution mixing technique. Differential scanning calorimetry results illustrated that adding a small amount GO facilitated the nucleation of PA 46. Avrami analysis showed a decrease in the dimension of PA 46 crystal growth in the composites because of a constrained environment formation. The equilibrium melting temperature (Tm) of PA 46 increased in the composites,. Laser flash analysis exhibited that thermal conductivity of nanocomposites increased 50 % compared with neat PA 46. The thermal stability of nanocomposites was also improved.
Reparation and Properties of Polyurea/Graphene Oxide Composites
Two surface modifiers, phenyl isocyanate, and poly(ethylene glycol) (PEG800), which have different affinities to the hard and soft segments in polyurea, were used to synthesize functionalized graphene oxides (GO). After the modification, the PEG800-modified (PEG800-GO) and phenyl isocyanate-modified (i-GO) GOs were highly exfoliated and dispersed in DMF. Using the suspension of the functionalized GO,. Polyurea/GO composites were prepared using a solution-blending method.It was shown that PEG800- GO and i-GO are uniformly dispersed throughout the polymer matrix on a nanoscale. The well-dispersed GO platelets improved the thermal stability and mechanical properties of polyurea. PEG800-GO, which has a strong affinity for the soft segments, shows a more significant reinforcing effect. At 2.0 wt% GO, the tensile strength of polyurea was enhanced by ~75%.
The Effect of a Vibration Force Field on the Crystallization and Barrier Properties of Polymer Nanocomposites
High-density polyethylene (HDPE)/nano-SiO2 and polypropylene (PP)/nano-SiO2 films have been prepared by two different processing conditions; i.e., under traditional steady state (TSS) conditions and with a vibration force field (VFF). The aim of this research is to study the crystallization and barrier properties of films manufactured under different processing conditions. The results showed that the barrier and mechanical properties of the nanocomposites processed under the VFF condition were superior to those processed under the TSS condition. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were used to characterize the crystalline structure and morphology of the films, which provided evidence for explaining the distinct barrier and mechanical properties under the two processing conditions. DSC and SEM results clearly showed that an increase in the degree of crystallinity and orientation of the lamella were found in the nanocomposites prepared under the VFF condition.
Conductive Polymer Nanocomposites Made by Selective Laser Sintering
This research focuses on manufacturing multifunctional polymer nanocomposites (PNCs) using selective laser sintering (SLS). Carbon-based nanofillers such as carbon fibers, carbon nanotubes, carbon black, and graphene can be used to induce thermal and electrical conductivity in polymers, enabling them for a wide range of applications that require lightweight multifunctional materials. In this study, the SLS processing of PNCs of polyamide-12 (PA) with graphene nanoplatelets (GNP) at 3 and 5 wt% is optimized to achieve PNCs that are nearly fully dense and exhibit homogeneous dispersion and distribution of the platelets. Observation of the filler-coated polymer’s microstructure after compounding and SLS processing shows the most homogeneous dispersion of nanofiller with GNP at 3 wt%. At 3 wt% the highest tensile modulus (2.1GPa) is also achieved. The part density of the optimally SLS-processed neat PA and PNCs are all nearly fully dense (>96%) and the highest density (99.5%) is again found at 3 wt% GNP.
A Moldflow 2012 Validation Study: Material Properties Versus Simulation Accuracy
The usefulness of thermoplastic injection-molding simulation is influenced by many simulation inputs – such as the modeling of part geometry, mesh type and density, mathematical solution, process settings, and plastic material properties both as melt and as solid. Since 2008, much progress has been made with regards to meshing capability and to having robust solution algorithms, but the material properties data file still remains as a weak link in the simulation process. This paper reviews the results of a validation study that focused on the influence of the material properties data file on the precision and accuracy of Moldflow 2012.
Hydrogen Bonding Mediated Microphase-Separated Structures in SBM Triblock Copolymer Blends
The self-assembly of ABC triblock copolymer/homopolymer blends where the homopolymer is miscible with one of the blocks (C) and immiscible with the other two blocks (A and B) of the block copolymer were investigated. The well-known proton donating polymers, -namely, phenoxy and poly (4-vinyl phenol) (PVPh) were used to prepare the self-assembled SBM triblock copolymer blends. In these blends, microphase separation takes place due to the disparity in intermolecular interactions; specifically, the homopolymer interacts with PMMA blocks through hydrogen bonding interactions. In both PVPh/SBM and phenoxy/SBM blends, order to disorder morphology transitions were observed with increase in homopolymer content. The TEM and SAXS results of phenoxy/SBM show lamellar, bicontinuous and other disordered nanostructures; whereas in PVPh/SBM, lamellae, hexagonal close packed cylinders, and other complex disordered nanostructures were observed. Here we examined how intermolecular hydrogen bonding interaction between the homopolymer and block copolymer can alter the morphologies of the blends.
Thermally Conductive and Electrically Insulating Hexagonal Boron Nitride-Filled Polyphenylene Sulfide Composites
This paper examines polyphenylene sulfide (PPS)-based composite materials filled with different types of hexagonal boron nitride (hBN) particulates. It aims to investigate the effect of filler geometry on the multifunctional properties of the polymer-matrix composites (PMCs). Experimental results revealed that the PPS-hBN composite filled with hBN platelets of varying particulate sizes and shapes led to the largest improvement in the PMC’s effective thermal conductivity. It also led to the greatest reduction in the PMC’s coefficient of thermal expansion. In addition, the electrical of the PPS-hBN composites were studied. It was found that the addition of hBN did not compromise the electrical resistivity of neat PPS. In terms of PPS-hBN mechanical properties, the PMCs’ compressive moduli were promoted while their compressive strengths were suppressed. In short, the size and shape of hBN particulates would influence the thermal, electrical, and mechanical properties of the PPS-hBN composites.
Characterization of Acrylonitrile Butadiene Styrene (ABS) Containing Foreign Polymers Using Fracture Mechanism Maps
For the commercial production of consumer products using engineering polymers, it is very important to control physical properties of the material. However, due to many reasons, e.g. cost reduction, cleaning issues, using scraps etc., the quality control of the material is not easy. In many cases, the effect of a small amount of foreign polymers on product failures is well known, but it is difficult to analyze them by conventional analytical techniques. So, in this paper, the methodology of evaluating the durability of Acrylonitrile Butadiene Styrene (ABS) copolymer containing foreign polymers using fracture mechanism maps is introduced. In addition, as a quantitative tool, the importance of the ductile-to-brittle transition temperature (DBTT) is discussed.
Evaluation of Heat Transfer Conditions to the Mold Temperature Stabilization in the Injection Molding Process
In order to keep the part quality under a stable mold temperature, a number of parts should be discarded until the mold temperature reaches to a stable condition. Depending upon process and environmental conditions, the time to a stable condition varies. In this work, influencing factors to the stabilized mold temperature condition are examined. The results show that ambient temperature significantly affects the stabilization time. To predict the stabilization time with consideration of heat transfer to the molding machine, heat sink attached model in the CAE analysis was suggested. It shows a good agreement with experimental result.
Buckling Prediction in 3D Warpage Simulation of Injection Molded Plastics
Buckling analysis is useful for identifying if thin-walled polymer injection molded parts buckle due to in- mold residual stresses after ejection. However, traditional direct-solver-based eigen-solvers become prohibitively expensive for large-scale three-dimensional (3D) finite element models for injection molding simulation. A new fast parallel eigen-solver has been developed, which combines an algebraic multigrid preconditioned conjugate gradient (AMG-CG) equation solver with a subspace eigenvalue iteration algorithm, making the large-scale 3D buckling analysis feasible for industrial applications. The buckling analysis has been extended to the injection over-molding process. Buckling analysis results for a simple tray model and an insert over-molded part are presented.
Using Iterative Fluid-Structure Interaction Solution to Simulate Core Deflection Problems in Injection Molding
In injection molding process, the fluid-structure interaction (FSI) issue has been widely discussed, especially for core shift deflection problem recently. During the filling stage, a non-uniform pressure distribution within the cavity leads to common structural deformation defects. At the same time, the deformed structure affects filling behaviors. These dynamic deformations and fluid mechanics result in the difficulties of maintaining numerical simulation accuracy and huge computational memory. In this paper, a new iterative FSI coupling method has been developed. The new method not only provides more accurate melt front and pressure result but also predict precisely core deflection simultaneously. Furthermore, a new solid mesh deformation technique is used to rebuild cavity solid mesh automatically in accordance with continually deformed cavity geometry. Moreover, a real case is applied for both numerical simulation and experimental study to validate the iterative FSI coupling method. The results in this paper demonstrate that the high quality deformed meshes are reliable and help to get a good agreement with experiment.
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