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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Migration of Fluorinated Additives to HDPE Film Surfaces
The surface concentration of fluorinated additives has been investigated in high density polyethylene (HDPE) films. These additives have been used as processing aids and are presently being studied as surface-property modifiers to lower the surface energy for applications where hydrophobicity is important. We have used ATR-FTIR and ESCA to characterize the composition of these modified film surfaces. Results indicate the extent of surface segregation as a function of additive molecular weight and bulk loading.
Measurement of Microstructural Variation in Blown Films
A real-time study on the evolution of molecular structure in an isotactic polypropylene blown film (i-PP) is reported. The structural variation along the machine direction of the film has been observed with online Raman spectroscopy. Preliminary measurements indicate a variation in the intensity of 809 cm-1 peak relative to the 841 cm-1 peak as the state of the polymer changes from a melt to solid at the freeze line. This change is related to the development of crystallinity along the film line.
New Manufacturing Method for Light Guide of PMMA
The market share of LCD in display devices is now growing rapidly. Especially many LCD makers have had their efforts to develop the LCD module not only with thinner and wider panel but also with cost competitiveness. In this study, we propose a low-cost alternative manufacturing method for the light guide of PMMA, which is one of important components in the backlight system of the LCD module. This manufacturing method is called the direct surface forming (DSF), which may be also called the well-known hot embossing. We present the results of this manufacturing method in terms of dimensional accuracy, productivity, etc.
On the Use of Rotational Rheometry for Quality Control
The aim of this work is to evaluate if rotational rheometry provides a more useful measurement of viscosity than capillary rheometry and melt flow index measurements in production environments. To achieve this, we compared the sensitivity of these methods for quality control in the batch production of a commercial fluorinated polymer by using statistical analysis and the ease-of-implementation criterion of each method. The utility of rotational rheometry to develop flow curves to assist blending in a batch process was also investigated.
Status of Research on Design for Mechanical Reliability of Injection Molded Plastics Products
Various injection molded specimens and specimens from injection molded products have been tensile and tensile-impact tested to develop manufacturing-related design guidelines. Tensile strength of PS perpendicular to flow was affected by both filling-induced and packing-induced phenomena. For a nylon block copolymer the influence of test speed was shown. Cold weld line strength in PS was reduced by increased temperatures in the skins during molding. For polyester-amide and PHB the amorphous structure fraction contributed to reduced weld line strength.
Process Dynamics in Sequential Valve Gate Injection Molding - Processing Strategy and Process Control
The process dynamics of sequential valve gate injection molding were investigated using multiple pressure transducers in a single cavity. System response is analyzed based on the servo valve signals and the cavity pressure profiles. The optimum process control and part quality control settings of the Sequential Valve Gate system were determined. Also, the experimental results were compared with the predicted results obtained from a simulation program.
PMMA Thermal Degradation and Modeling of Weight Loss Experiments
Residual polymerization catalyst can be detrimental to the thermal stability of polymers. We used thermogravimetric analysis (TGA) to demonstrate that the thermal stability of poly (methyl methacrylate) (PMMA) decreases upon doping with a transition metal catalyst. This effect could be reversed by adding a chelating agent to the doped PMMA. In addition, we modeled the TGA weight loss experiment. The modeling verified that weight loss for the experiments was not diffusion controlled and that weight loss linear with the square root of time does not necessarily indicate diffusion control.
Fracture Toughness of Co-Continuous Polycarbonate/ABS Blends
Polycarbonate/ABS blends are industrially important however very little reported on in literature. Co-continuous PC/ABS (50/50) blends were made on a twin-screw extruder and tested in notched Izod at different temperatures and different rubber content in the ABS. Ductility improved strongly with increasing rubber content in the ABS (Tbd lowered to about -40°C) with little decrease in modulus.
Numerical Simulation of Injection Molding of Semicrystalline Thermoplasti
Injection molding process of semicrystalline plastics was simulated with a stress-induced crystallization model. Pseudo-concentration method was used to track the melt front advancement. The stress relaxation was incorporated into the model using the WFL model. Simulations were carried out under different processing condition to investigate the effect of processing parameters on the crystallinity of the final part. The simulation results reproduced most of the features reported in the literature.
Process Fingerprints for Compounding of Polymer Blends – An Industrial Prospective
A process fingerprint measurable by on-line monitoring of common process variables could aid immensely the ability of a process engineer to control the process output. The torque curve of a Brabender batch internal mixer offered many fingerprints related to the fundamental behavior the raw ingredients experienced during the mixing process. Suggestions were made how to derive fingerprints from the fundamental functions of twin screw extrusion processes.
Model Based Prediction of Permeability in Preform Materials
Knowledge of the permeability tensor in liquid composite molding is important for process modeling and optimization. However, experimental determination of the permeability is difficult and time consuming. In this work, a lattice Boltzmann simulation which has been modified for flow in porous media is used to predict permeability as a function of yarn location, orientation, and fiber fraction. Calculated permeabilities are compared with experimental measurements for a variety of systems. Good agreement is achieved as long as the mesh size is greater than the size of the smallest throats in the porous medium.
Rheological Behavior of Modified Polypropylene (PP) with Nitrile Rubber (NBR)
The rheological behavior of polypropylene (PP) modified with nitrile rubber (NBR), within the composition range of 10-30 wt% NBR content, was studied based on the blend ratio, dynamic vulcanization and additives blending effects. Results indicate all systems show a pseudoplastic behavior with an increasing melt viscosity on NBR content. Dynamically vulcanized blends present similar melt viscosity and lower die swell values than corresponding unvulcanized blends. The rheological behavior was correlated with blend morphology.
Interaction between PVA and Starch System Plasticized with Different Moisture Content
We investigated the interaction between PVA and starch blended series plasticized with different moisture content. Brabender plasticoder was applied to research the effect of gelatinization of water plasticized starch on the processability of this series. The moisture content of this series was furthermore found increasing with the increase of relative humility in different ambient condition.
Morphology Distribution of Injection Molded Polypropylene
The morphology distribution of injection-molded polypropylene (PP) was quantitatively studied using synchrotron radiation. Samples were taken from a PP plate at different positions from the gate. X-ray measurements were performed with the beam normal to the flow direction. The evaluation of x-ray data allows determination of distributions of the crystallinity, the imperfection factor, the á-phase orientation, and the â-phase concentration. Different distributions are observed at different distances from the gate.
Rheological Probing of Structure in Polypropylene / Clay Nanocomposites
Polypropylene/clay nanocomposites have been prepared with a variety of hybrid structures by melt mixing a fixed amount of organically modified clay, different levels of a maleated polypropylene and polypropylene. The structure has been investigated with X-Ray diffraction and transmission electron microscopy. An optimum level of maleated polypropylene is found to yield the greatest degree of exfoliation in polypropylene. The relative viscosity curves reveal a systematic trend with the extent of exfoliation and show promise for quantifying the hybrid structure of the nanocomposites.
Documenting Flow Segregation in Geometrically Balanced Runners
The flow distribution through a geometrically balanced runner is not evenly balanced due to the melt temperature segregation that occurs at each branch point in the runner. A test mold is built and molding trials are conducted to document the flow segregation in a four cavity mold containing a geometrically balanced runner. The extent of the flow segregation is seen to be a function of the resin type, the flow rate, and the extent of the filling.
The Effect of Blending on the Viscosity Reduction of Recycled Milk Bottle Grade HDPE
Post-consumer plastic waste in Australia contains over 50,000 tonnes p.a. of HDPE blow moulded bottles, with half still ending up in landfill. Recycled milk-bottle grade HDPE is known to be too high in molecular weight for processing by injection molding. In this study, the target was to make injection-molded compositions with a content of the recycled material of 75% or higher by blending with commodity plastics. The results of rheological, thermal and mechanical studies of the blends are presented.
Rheology and Processing of TPV's
The rheological behavior of TPV in shear and extensional is studied to help understanding the flow behavior in various processing operations. The TPV's, which are dynamically vulcanized PP/EPDM blends show in shear flow a typical rheological behavior with an apparent yield stress at low shear rates and a shear-thinning viscosity at high(er) shear rates. In extension the TPV melts appeared not to show strain-hardening. This study discusses the observed behavior in terms of composition.
Impact Modification of Poly(Ethylene Terephthalate)
Many polar thermoplastics, such as poly(ethylene terephthalate), tend to be notch sensitive and can exhibit a sharp ductile-to-brittle transition. Many studies focusing on the improvement of toughness using elastomeric particles have demonstrated that the increase in toughness is related to the ability of the rubber particles to cavitate and to morphological parameters. In this work, the mechanical properties of a poly(ethylene terephthalate) matrix containing several impact modifiers are investigated.
Processing-Structure-Properties Relationships in Multilayer Films
LDPE/PET multilayer films with and without a reactive tie layer were prepared by extrusion blowing process. PET layer showed a negligible orientation and an almost zero crystallinity. For PE layer, the crystalline a-axis was oriented along machine direction and the b-axis mainly tended to the transverse-normal plane, no orientation for amorphous phases was found. A morphological model for the different processing conditions was proposed. The shrinkage and tear strength correlated well with the orientation structure of the LDPE layer in the films.
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