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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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.
Effect of Polyurethane Surface Treatment on the Thermal and Mechanical Properties of Glass Fiber Woven Composite
In this paper, the effects of fiber surface treatment on the mechanical and thermal properties of glass woven fabric reinforced thermosetting epoxy resin matrix composites are examined experimentally. Four kinds of deposit (pick-up) ratios of polyurethane dispersion (PUD) treatments on the heat-cleaning glass cloth woven fabric were carried out, including 0wt% (without treatment), 0.76wt%, 1.51wt% and 6.49wt%. It is found that the interfacial adhesion and property were affected by the treatment significantly. The correlation among varied PUD surface treatment pick-up ratio of glass fiber, modified interface, improved mechanical property and related thermal property were discussed and clarified based on tensile test, dynamic mechanical analysis (DMA), scanning electronic microscope (SEM) observation.
Blend of Polypropylene and Polyphenylene Ether
The effect of the blending sequence and the viscosity ratio on the phase morphology and mechanical properties of blends of polypropylene and polyphenylene ether was investigated in present study. It is found that that the Izod impact strength of PPE/PP alloy compounded via two step extrusion method can be improved significantly. A preblending SEBS with PPE can make the compatibilizer SEBS move easily to the PPE/PP interface and the blends had finer dispersion and better properties. Also, the experimental results have showed a clear dependence of the blend phase morphology and properties on the viscosity ratio. The Izod impact strength of PPE/PP blend can be improved by decreaseing the viscosity ratio ?PPE/?PP. In addition, the screw configuration containing an elongational flow field has proved to be more effective in deforming particles than a shear flow field, leading to finer dispersion and better properties.
Preparation and Characterization of Poly(N-Isopropylacrylamide)/Graphene Nanocomposites Hydrogel
Graphene oxide/PNIPA ?GO/PNIPA ?composite were successfully prepared through in-situ polymerization. And then using chemical reducing agent, GO/PNIPA was reduction tographene/PNIPA composite. Resulting hydrogels were characterized by FTIR, scanning electron microscopyto investigate the structural, morphologicalproperties. The swelling ratio and response kinetics on heating or cooling were also investigated to understand the smart properties. The result indicated that graphene/PNIPA hydrogel showed good smart property with a higher swelling ratio and more complicated deswelling behavior.
Effect of Small Perturbations in Colour Formulation on Output Colour of a Plastic Grade Compounded with Two Polycabonate Resins
Historical colour data of a compounded plastic grade manufactured at Sabic IP Cobourg Plant has been analysed through statistical means. Objective was to investigate response of output colour to small adjustments in pigments standard formulation recommended to impart desired colour to a plastic grade. The Plastic grade studied was a blend of two polycarbonate resins, five additives and four colour pigments including one organic – the black pigment, and three inorganic - white, red and yellow pigments. Color mismatch caused by these adjustments is presented in terms of dL*, da* and db*. Analysis of colour deviation caused by such adjustments reveals that output colour values are more sensitive to perturbations in white and yellow pigments amount compared with black and red. Results of optimization carried out to minimize colour deviation, are also presented for the plastic grade.
Experimental Study to Investigate Effect of Process Variables on Output Colour of a Compounded Plastic Grade
For plastic compounders it is imperative to acquire a profound understanding of relationship between extrusion process variables and compounded plastics colour for achieving consistency in output colour. Compounders also need to take educated and precise decisions while incorporating any changes in process variables to minimize deviation of output response from target colour for a compounded plastic. Such a relationship has been investigated using an efficient and economic design of experiments (DOE) for a polycarbonate resin-based compounded plastic. Present study has discussed the results of designed experiments and shed an insight on individual as well as combined influence that process parameters impose on output colour. Three process parameters under study are temperature, feed rate and screw speed. Results of confirmation DOE has also been discussed, which have verified fitness of statistical model used for analysis. The study further suggests a set of optimal process conditions that could be implemented ensuring consistency in compounded plastic colour with minimum deviation from target.
Towards a High-Performance Epoxy Resin Free of Bisphenol A (BPA)
Bisphenol A is a key component of many epoxy resins, but is under pressure especially in food contact applications, necessitating the identification of high performance alternatives. In this work we report on the preparation, properties and performance of one such alternative, the bis(epoxide) of 2,2,4,4-tetramethyl-1,3-cyclobutanediol. This resin has been crosslinked with a typical amine hardener to produce a stiff, hard thermoset with a high Tg. Curing behavior and cured resin properties are improved vs. the bis(epoxide) of cyclohexanedimethanol, a structural isomer of CBDO. Compared to a BPAbased equivalent, resin viscosity and UV cutoff are lower and lap shear adhesion to mild steel is superior, the latter on par with a commercial heavy duty epoxy adhesive. These results indicate promise from this material as a high-performance BPA-free epoxy resin.
Foaming of Cellulose Fiber Reinforced Polylactic Acid Composites: The Effect of Cellulose Fiber Type
This paper investigates the effect of fiber type and fiber content on the foaming behaviors of cellulose fiber reinforced polylactic acid composites. Two types of cellulosic fibers with different sizes were used: micro- and nano-sized fibers. The composites were prepared by a film casting and hot pressing method and then foamed via a batch foaming process with CO2. The morphology and volume expansion ratio of the samples with different cellulose fiber contents were compared. The results suggested that micro-sized fibers had negative effects on the foam morphology and nano-sized fiber positively influenced the foam morphology. It is speculated that the crystals generated around the fibers affected the cell morphology significantly.
Challenges in Qualification of Open Loop Post Consumer Recycle Polystyrene for its use in Engineering Thermoplastics
Polyphenylene Ether (PPE) is an engineering thermoplastic resin usually blended with polystyrene (PS) [crystal polystyrene (CCPS) and or High Impact Polystyrene (HIPS)] to improve properties including the processability. The overall performance of the resulting Noryl™ resin is highly dependent on the quality of the PS. This study presents some of the challenges involved in qualifying open loop PCR PS and key factors that could have affected their performance due to the recycle history and contaminations of the raw material compared to the virgin PS. PCR HIPS properties were simulated by recycling & spiking virgin HIPS with the contaminations.
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