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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A STUDY OF INJECTION MOLDING OF THE BARREL FOR THE OPTICAL LENSES
A study of the barrel for the optical lenses based on the design of experiments is presented. The barrel provides an installation space for lenses to assembly. Therefore the optical characteristic of the mini projector is dominated directly by the lenses and the barrel. In this study, we analyzed the effect of the part thickness on the warpage by commercial software and investigated the influences of the molding conditions on the part quality experimentally. The study provides a systematical way to predict in which area a defect lies and determine the optimal injection velocity and holding pressure through statistical experiments.
STUDY ON PREPARATION OF PP/PA6/OMMT NANOCOMPOSITES AND BATCH FOAMING PROCESS CONDITIONS WITH VIBRATION FORCE FIELD
The composites of polypropylene/polyamide-6nano-organ-montmorillonite (PP/PA6/OMMT) with superior comprehensive properties were prepared using PP-g-MAH as compatibilizer prepared by dicumyl peroxide/benzoyl peroxide. It was shown that the addition of PP-g-MAH and OMMT nanoparticles improved impact strength and tensile strength as well as melt strength. Microcellular batch foaming equipment with Supercritical CO2 was used to study the foaming conditions of composites including foaming temperature, rotor rate and vibration force. The results presented improved microstructures, uniformed distribution, and the enhanced density resulting from employing vibration force field to shear stress force field.
SIMULATION ON THE PART WARPAGE AND PHOTOELASTIC STRESS WHEN MOLDING DISCONTINUOUS-THICKNESS-VARIATION PARTS COMBINED WITH DIFFERENTIAL MOLD COOLING
Discontinuous-Thickness-Variation (DTV) is used to interrupt the continuous shrinkage locally to minimize warpage. Matching of DTV with various mold temperature differences between the mold core and cavity sides was performed. The combined effect can be quantitatively described by a design guide chart. Case studies also verify its effectiveness. Simulations were conducted to calculate the neutral axis shift and the frozen layer thickness difference due to the unbalanced cooling. The analysis indicates that variation in thickness will pull the deviated neutral axis and photo-elastic stress due to unbalanced cooling back to the center line, leading to a significant part warpage reduction.
SYNTHESIS OF THE SILICA PARTICLES GRAFTED WITH POLY(IONIC LIQUID) AND ITS APPLICATION IN FOAMING OF POLYSTYRENE
Poly[2-(methacryloyloxy)ethyl]trimethylammonium tetrafluoroborate (P[MATMA][BF4]), as a novel poly(ionic liquid) for the strong absorption of carbon dioxide (CO2), is grafted to silica particles by using a surface-initiated atom transfer radical polymerization (ATRP). Silica particles modified by P[MATMA][BF4] (SiO2-P[MATMA][BF4]) play as nucleating agents to produce polystyrene (PS) foams using supercritical CO2 as a blowing agent. Compared with amino-functionalized silica particles (SiO2-NH2), SiO2-P[MATMA][BF4] exhibits higher heterogeneous nucleation efficiency in the foaming process. The morphology characterization indicates that PS/SiO2-P[MATMA][BF4] composite foams have higher cell density and smaller cell size than those of pure PS and PS/SiO2-NH2 composite foams.
INVESTIGATION OF THE THROUGHPUT OF A SINGLE-SCREW EXTRUDER TAKING INTO ACCOUNT PRESSURE VARIATIONS DURING A STEP CHANGE IN SPEED
Extrusion is used to continuously manufacture endless plastic products such as tubes, profiles etc. An essential aspect during the manufacture of semi-finished products is the products' uniform wall-thickness, whereby the manufacturing costs are decisively influenced. The material output is fundamentally influenced by both changing the operating points and from pressure variations in the extrusion process. On changing the operating point, a steady operating point is to be obtained as rapidly as possible in order to minimise the production of rejects. Moreover, a uniform wall-thickness is to be obtained by means of reducing the pressure variations in the extrusion process.
NEW DEVELOPMENTS IN FLAME RETARDANCY OF POLYOLEFINS
Polyolefins are highly flammable and it is very difficult to flame retard them. Relatively high loadings of flame retardants are often used in order to achieve UL-94 V-0 rating in these polymers. ICL-IP has developed new flame retardant systems which allow overcoming many of these limitations. This paper presents results on flame retardant performance and physical properties of number of polyolefins flame retarded with highly efficient bromine based flame retardants, polymeric flame retardants and combination of bromine and mineral flame retardants. New data is also presented on phosphorus-based flame retardants for polyolefin films and sheets.
CONTROL OF TEXTURED IONOMER SURFACES
Textured surfaces consisting of nanometer to micrometer-sized lightly sulfonated polystyrene ionomer (SPS) particles were prepared by evaporation of the solvent from a polymer solution cast onto silica. The structure of the particles and aggregates were controlled by the rate of solvent evaporation. The surface morphologies were consistent with spinodal decomposition mechanism where the surface first existed as a percolated-like structure and then ripened into droplets. The SPS particles resisted deformation after annealing at 140C for one week. Water droplets stuck to surfaces even when tilted 90 degrees, making them candidates for applications requiring high adhesive forces, such as cleaning robots.
PHENOMENON-ORIENTED PROCESS AND PART OPTIMISATION OF COMPLEX INJECTION MOULDED PARTS WITH THIN-WALLED MOULDED-ON HOLLOW AREAS (GITBLOW), TAKING INTO ACCOUNT THE RESIDUAL WALL THICK-NESS DISTRIBUTION
In the GITBlow-process it is possible in a second stage to further inflate the hollow-area produced by gas-injection molding (GIT). In recent years, specific GITBlow-process-pheno-mena relating to the inflation of moulded-on hollow areas have been identified. On the basis of these findings, and with the help of developed methods, it is now possible to draw wide-ranging conclusions about the residual wall-thickness-distribution in the final part. Aim of this paper is to assign these process-phenomena relating to wall-thickness-distribution to their respective influencing parameters. By developing an analysis-methodology, this project sets out to derive and describe part-optimising principles concerning the result-ing wall-thickness-homogeneity.
THE POTENTIAL OF NANO-STRUCTURED FILLER MATERIALS TO IMPROVE THE STIFFNESS/TOUGHNESS BALANCE OF PA 6
While developing new polymers, a high level of stiff and simultaneously tough material behavior is an important goal. This study shows a novel approach to optimize the stiffness/toughness behavior of polyamide 6 (PA 6) by incorporating nano-structured filler materials. For stiffness enhancement of PA 6, an organic modified clay material was used. To compensate for the toughness properties, a nano-structured polyamide 6/polyether block copolymer was used. Following an analysis and optimization of the binary material systems, the knowledge was transferred to develop a ternary material system.
REVISIT YOUR EXISTING PARTS ƒ?? FLOW SIMULATION MAY OFFER SIGNIFICANT COST SAVINGS THAT ARE LURKING BENEATH THE SURFACE
The part cost is one of the most important factors when designing a plastic part. However, there have been many-many parts designed over the years that do not follow fundamental plastic design rules. Parts designed without proper knowledge about plastic design principles, eventually affects the part performance and cost. Not only does the part become costly, but the manufacturing cost also increases significantly. This paper presents an example how a flow simulation helped optimize the design of a part and resulted in significant improvement in performance and reduction in part cost.
MODELLING OF THE AGEING PROCESS ON THERMOPLASTIC SURFACES AFTER TREATMENT WITH AN ATMOSPHERIC-PRESSURE PLASMA
After treatment with an atmospheric-pressure plasma, thermoplastic surfaces exhibit marked aging phenomena. These become apparent as changes in the surface properties over time. Although these effects are adequately documented in literature, no generally functional relationship yet exists to describe them. Therefore this study was undertaken. Various thermoplastics were treated with an atmospheric-pressure plasma and subsequently kept under constant conditions. At defined intervals, the surface energy was determined with test fluids on the substrate surface. Taking mass transfer mechanisms into account, an initial approach is then described for modelling these thermoplastic surface properties vs. time following treatment with an atmospheric-pressure plasma.
PREPARATION OF A UV-CURED, UV-ABSORBING COATING
Creating UV-cured coating containing UV-absorbing materials is akin to getting a suntan while wearing sunscreen. Despite this contradiction, we did just that. Motivated by concerns over CO2 emissions and economics, we sought to replace a solvent-based, UV-absorbing coating with an equivalent UV-cured formulation. This was ultimately achieved through creative formulation efforts. Besides being solvent-free and non-flammable, the coating is processed with equipment having a significantly smaller footprint than the older equipment. An additional, unexpected benefit of the new formulation was that the viscosity was significantly lower. This allowed for a significant reduction in coat weight, further reducing the overall costs.
MANUFACTURABILITY STUDY OF NANO-ENHANCED FIBER REINFORCED POLYMERIC COMPOSITES (FRPC)
One of the most environmentally friendly energy generation methods is wind power. In order to compete favorably with the cost of traditional energy generation methods, the wingspan needs to increase from current dimensions. For this to occur, taking advantage of new material developments in nano-reinforced composites is essential. The use nanoparticles have shown improvement in mechanical properties of FRPC. Understanding the manufacturability of these processes is critical, especially during VARTM. Understanding the factors affecting the flow through porous media and the inherent material properties, such as permeability and viscosity, of these nano-enhanced FPRC was the objective herein.
THERMOFORMABLE BRIGHT FILM FOR TPO APPLICATIONS
Thermoformable Fluorex Bright Film was developed to emulate the appearance of plated chrome. However, unlike plated chrome, Bright Film is flexible and thermoformable and can be applied to TPO. The film technology is environmentally friendly and cost-effective, and it has practical applications in various manufacturing processes, such as insert injection molding, thick-sheet thermoforming and extrusion lamination processes. Backed by successful weathering and other testing results, Bright Film has been accepted by the marketplace to accommodate or replace chrome plating as a decorative material for both interior and exterior finishes in the automotive and other industries.
ANALYSIS OF MORPHOLOGY ON INJECTION MOLDED POLY (?æ-CAPROLACTONE) TISSUE ENGINEERING SCAFFOLDS
PCL/NaCl and PCL/PEO/NaCl were injection molded. The water soluble, sacrificial polymer, PEO, and NaCl particulates in the blend were leached by deionized water to produce porous and interconnected microstructure. The effect of leaching time on porous morphology and porosity was investigated. Results showed that PCL/NaCl blend composites had a relatively slow leaching rate due to a lack of connectivity between NaCl particulates. For PCL/PEO/NaCl blend composites, most of the PEO and NaCl particulates can be removed in a short time. This is because the leached PEO domains provide interconnected channels that allow water to reach and leach embedded NaCl particulates.
DEVELOPMENT OF COMPOSITE PIPES FOR RISER APPLICATION IN DEEP WATER
This work deals with the development of composite pipes for riser application in deep water. Initially, an epoxy resin system was toughened by rubber CTBN addition (10 wt%) as a way of improving the flexibility of future risers. Mechanical and thermal analyses were carried out for characterizing the polymeric systems. The influence of matrix toughening and the number of composite layers on the mechanical behavior of the tubes were studied using hydrostatic and split-disk tests. In both tests, the results indicate that the matrix plays an important role in composite fracture processes
THE USE OF PRESSURIZED WATER PELLETS AND SUPERCRITICAL NITROGEN IN INJECTION MOLDING
In injection molding, cycle time, and warpage are critical factors for process economics and product quality. This work focuses on reducing cycle time, and warpage by utilizing water containing polymer pellets. Pellets were prepared by compounding a water carrier particle via extrusion, followed by a batch pressurizing process at a controlled pressure and temperature. Water containing polymer pellets were molded with and without supercritical nitrogen to further decrease the cycle time and minimize warpage. Preliminary results showed that the cycle time and part warpage could be reduced without a major effect on the mechanical properties.
FEM PARAMETRIC STUDY ON EFFECT OF CONSTITUTIVE BEHAVIOR ON SCRATCH VISIBILITY RESISTANCE OF POLYMERS
Three-dimensional finite element method (FEM) parametric study was performed to investigate the effect of asymmetric constitutive behavior on scratch visibility resistance of polymers. The scratch depth and shoulder height of the groove formed during the scratch, which is related to the scratch visibility resistance of polymers, is simulated by considering different asymmetric constitutive behaviors. The simulation results indicate that compressive behavior dominates the scratch visibility resistance of a polymer. Implication of the present findings for designing scratch resistant polymers is discussed.
MAINTAINING A STABLE ENGINEERED NANO-COMPOSITES PROCESS THROUGH MATERIAL CHARACTERIZATION
There is excitement regarding the application of nanomaterials (NMs) in composites. The use of carbon nanotubes (CTNs), nanoparticles (NPs), or other NMs in composite epoxy materials increase strength and elasticity, and reduce the weight of the end product. Nano Composite Epoxy materials will introduce new and unique composite characteristics for industry and consumers. Characterizing NMs during their composite processing is quite different than characterizing previous bulk composite additives. There are additional concerns and characteristics to be aware of with NMs. This paper is an overview of nanomaterial characterization needed to ensure a stable nano-composite epoxy process from beginning to end.
MULTI-LAYER BLOWN FILMS FOR THERMOFORMED FOOD PACKAGING APPLICATIONS
Polyethylene and nylon are used in thermo-formable, multilayer films for food packaging. Through this study, we have developed film structures with up to 30% less nylon and equivalent or better oxygen and moisture barriers than a commercial pizza packaging film structure. These structures exhibited good thermoforming behavior at several draw ratios. We have applied three thermoform-ability indices for the assessment of a filmƒ??s thermoform-ability in this study. One of them was the dimensional thermoform-ability index reported by NOVA Chemicals Corp. The combination of all three indices provides rapid and accurate assessment of the thermoform-ability of film structures.
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