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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Advances in Supercritical Fluid Processing of Carbon Nanotubes for Applications in Melt Compounded Polymer Nanocomposites
Supercritical carbon dioxide (scCO2) was used as a processing aid to disintegrate multi-walled carbon nanotube (MWCNT) bundles followed by melt compounding the MWCNTs with polycarbonate to generate nanocomposites with improved surface conductivity. The process incorporates the rapid expansion of a scCO2/MWCNT mixture to separate large primary carbon nanotube agglomerates followed by single screw melt compounding. High levels of deagglomeration of Baytubes? C 150 P and NanocylTM NC-7000 MWCNT bundles were observed on the macro- and nano-scale with scCO2 treatment, resulting in 30 fold and 50 fold decreases in bulk density, respectively, with median agglomerate sizes < 8 ?m in diameter. It was found that a temperature and pressure of 40oC and 7.86 MP resulted in maximum deagglomeration without damage to the MWCNTs. Following pretreatment with scCO2, PC/MWCNT nanocomposites were generated using melt compounding, yielding nanocomposites with enhanced electrical properties and improved dispersion.
Novel Effect Pigments for Cool Plastics
ENERGYSAFE pigments are designed to substantially increase the solar reflectance properties of plastics across a very wide color space. This pigment class reflects incident sun rays, i.e. near infrared radiation (NIR), visible light (VIS) as well as ultraviolet radiation (UV) - independently of the substrate. ENERGYSAFE functions inherently and thus does not need a reflective substrate.
Surfaces of plastic articles with high solar reflectivity will stay cooler under the sun's powerful radiation. ENERYGSAFE pigments will contribute to decreasing the rate of absorption of sunlight. This effect can lower the overall heat build-up, thus leading to plastics with reduced surface temperature. ?Cool Plastics? are consequently less prone to warping and torsion. Diverse colors from black to brown, from yellow to red, from white to silver can be achieved. Colorful plastics that are inherently solar reflective can extend the use of plastic materials, particularly for outdoor applications.
Processing of Conductive Polymer Composite Shielding Materials
The application of conductive filled polymers to Electromagnetic Interference mitigation has been shown to be an effective means of shielding with attenuation levels of up to 60 dB possible. These composites can be both injection molded and coextruded to form the desired geometry, though accommodation of sensitivities to technique is required to retain filler-dependent loading efficiencies. The variables associated with intrinsic conductive particle characteristics, their interaction with processing method, and achievable loading levels are described, as well as their impact on both electromagnetic and mechanical properties.
3D Thickness Mapping by Micro-Computed Tomography Aiding Design
Polyethylene Terephthalate (PET) is the most used packaging material for water and carbonated soft drinks. Raw materials used in making PET are typically based on non-renewable resources and does not biodegrade at the end of their service life. Designing PET bottles to use less PET significantly reduces carbon emissions. This involves optimizing the part design and manufacture process which requires advancing accurate techniques for thickness and physical property measurements. The bottle base section is one of the locations that can often be modified in a mold. Due to the complex shape and curved surfaces, thickness measurement on the base section is difficult. Here, a micro X-ray tomography method was used for thickness measurement and visualization. Knowledge of the final thickness distribution at different locations of the bottle base is beneficial for both design and process optimization.
High Performance PP/PE Multilayer Films Enabled by PP Based OBC
Dow has developed a new family of polypropylene (PP) based olefin block copolymers (OBCs). This novel family of block copolymers offers break-through system performance when used as a component in multilayer structures for combining polyethylene (PE), and PP. These multilayer systems offer unique combinations of properties such as high stiffness/toughness for a 5 layer blown film structure and high seal strength and low seal initiation temperature for a biaxially oriented 3 layer structure. The high performing multilayers allow for downgauging for heavy duty shipping sacks and standup pouches or cost saving for dry food packages. They also enable PE to participate in traditionally PP applications.
Innovative Supply Chain Management: How Big Data Advances Molders? Use of Resources and Promotes Competitiveness
Typically injection molding is a commodity service by which molders differentiate themselves with customer service, reliability and cost. While these aspects are still important, today it becomes necessary to also factor innovation and technology into one?s portfolio of services in order to remain competitive. This paper will look at technologies enabling supply chain monitoring, and how companies can utilize this to help bridge the gaps in communication that so often exist within the supply chain.
-In today?s business environment there is more transparency between molders and their customers.
-It used to be that relationships were the foundation for bringing in new business.
-Today it?s more about RFQ?s emailed to many potential suppliers to fill in cells on a spreadsheet
-OEM?s know every aspect of costs: Resin, packaging and hourly rates
-In some cases they dictate the vendors and have their own contracts in place
-RFQ?s are all about conversion cost and margin since everything else is known
-Need to create a way to differentiate / gain competitive edge between oneself and other molders
What is Big Data?
Something we should be embracing, not fearing.
Big data is as powerful and when used effectively, it provides businesses insights and value
When analyzing big data, you learn what you don?t know, and you?ll gain knowledge on what to focus efforts on
Why do we need Big Data?
What is it
How is it used
Continuous Improvement activities
OEM?s use to compare similar molds across supplier base
Automakers looking for cycle time savings
What is production monitoring?
Why is it important with molds?
Identifies tools that are degrading in performance allowing you to identify and address problems
Allows a mo
Viscoelastic Models with Rotational Recovery
Classical models for viscoelastic fluids typically assume that relaxation only occurs along the axial direction of the conformation tensor. A unsatisfactory consequence is that such models over-predict the strain softening effect in rotational flow such as simple shear. In this work, a new paradigm is proposed to formulate relaxation models with consideration of rotational recovery. Particularly, the relaxation models in the form of F=LF-1/?*(lnV+V^n*lnR*V^(-n)), where F is the deformation gradient, V is the left stretch tensor, R is the orthogonal tensor from polar decomposition, ? is a relaxation time and n is a material parameter, are particularly useful, with a flexibility embedded to adjust the straining and softening effect in 3-D flows. With this model, realistic shear thinning and elongational thickening can be simultaneously modeled and general agreements with experimental results are demonstrated.
Gel Spinning of UHMWPE Fibers with Low Molecular Weight Polybutene As a New Spin Solvent
Gel spinning of UHMWPE fibers using a low molecular weight polybutene (PB) as a new spin solvent was investigated. A 98/2 wt% PB/UHMWPE gel exhibits a melting temperature around 115øC and show a large-scale phase separation at room temperature. Experimental results show that the resulting precursor fiber from this gel is highly drawable and at a draw ratio of 120, tensile strength of 3 GPa and Young's modulus of 120 GPa can be obtained. Wide-angle x-ray diffraction indicates good molecular orientation along the fiber axis. The results also demonstrate the potential of further improvement of the mechanical properties. With respect to the gel spinning industry, this new solvent has a number of advantages and holds a promise of greatly improving the process efficiency.
Innovations in Hybrid Structural Instant Adhesive Technologies
Over the last century, adhesive use has become increasingly popular over other assembly methods for structural design. To meet the demands of the latest product designs and manufacturing processes, new adhesives are continually being formulated. Current cyanoacrylate and epoxy technologies have proved to be valuable in today?s largest manufacturing companies. Despite the many advantages, each technology still has its disadvantages that limit the materials and situations in which they are used. The recent advancement in hybrid adhesive technologies has allowed manufacturers to overcome limitations by increasing manufacturing speeds and assembly durability. Henkel has developed a structural instant adhesive, a hybrid epoxy and cyanoacrylate technology, whose benefits can be used to meet the demands of present and future production requirements.
The Effect of Microstructure on the Mechanical Properties of Thermoplastic Polyurethane/Clay Nanocomposite Foams
The microstructure and mechanical properties of thermoplastic polyurethane (TPU)/organoclay nano?composite foams were studied by scanning electron microscopy (SEM) and mechanical tests. The cell diameters of the TPU/clay foams became smaller, and the cell numbers significantly increased as the clay content increased. The relationship between clay content and the mechanical properties of TPU/clay foams was also investigated. The results showed that the mass density of nanocomposite foams was lowered by 12.5% when the clay loading level was 5% in the nanocomposite foams. Meanwhile, the tensile strength at 300% strain of the nanocomposite foams with 5% clay increased by 56.3%. Thus, this study shows that light weight, high strength TPU/clay nanocomposite foams can be produced by loading a moderate amount of clay into the TPU matrix.
Study on the Heat Transfer Behavior and Warpage Result in Small Quantity of Diverse Molded Part Designs with Varying Thermal Property Mold Insert Control
The cooling designs always play the most important role in the injection molding process; it is a major part of the total time during injection molding cycle. Therefore, the cooling system will directly affect the molding qualities, but different products shape, ejector pins and other complex mechanism usually restricted the effect of cooling efficiency, which may cause the uneven temperature distribution between core and cavity and leading the warpage issues.
In this study, a flash-drive cover mold which has an asymmetric cooling design between cavity and core was used to investigate the wapage under different mold temperature, melt temperature; packing pressure; cooling time and different mold insert material. The two kinds of mold-insert which has different thermal conductivity are implemented for evaluating cooling performance in experiment and numerical approach. The method in profile history variation of mold temperature and maximum temperature differential are established for predicting deflection level. The both experimental and simulated results show that using the high conductivity mold insert (QC-10) can effectively achieve the better uniform temperature between core and cavity that reduce the deformation of 56%. The increasing of mold temperature, packing pressure and cooling time, and the decreasing of the melt temperature can reduce the warpage.
Investigation of Applying Gas Counter Pressure (GCP) Technology in Improving Metal Injection Molding Flow Characteristics and Molded Part?s Quality
Metal Injection Molding (MIM) is a combination between injection molding and powder metallurgy process. The process bolsters a mass-production manufacturing of small, complex, precise parts as a molded part undergoes de-binding and sintering stages right after the molding one. Most of the MIM studies focus on how to treat the feedstock while to control the distribution of powder concentration and density through the process settings, for example, melt temperature, mold temperature, and injection speed is still less discovered. Therefore, this study investigates the effects of those settings on flow characteristics and molded part?s quality which focuses on the green part. Moreover, Gas Counter Pressure (GCP) technology is carried out to improve the process. Numerical approach along with SEM analysis is also conducted for verification, and the results exhibit that an anisotropic behavior occurs in experiment with different temperature and speed settings. In addition, both experiment and simulation have demonstrated that GCP implementation can improve both process and part?s quality; the shear stress is reduced up to 98.49%, and the density can be increased up to 1.43% in experiment and 0.01% in simulation.
Development of Sealants for Flexible Packaging Using Light Microscopy
Polyolefins used in flexible food packaging play a key role in enhancing our everyday lives. Food packaging extends shelf life, protects products from physical damage and keeps bacteria out. The development and design of food packaging require that scientists and engineers understand material properties, structure and performance. Analytical tools such as optical, scanning and transmission electron microscopies play key roles in material analysis and development at Dow Chemical. This paper provides an overview of how light microscopy (LM) techniques were used to evaluate heat seal performance such as hermeticity and hot tack in vertical form fill and seal (VFFS) packages. Having the ability to correlate heat seal temperature with performance is helping accelerate development of differentiated resins for flexible VFFS packaging.
Effect of Ultrasonic Treatment on Electrical and Rheological Percolation Threshold of Polycarbonate-Carbon Nanotubes Composites
A twin-screw extruder having an ultrasonic treatment zone was used to prepare polycarbonate (PC)/multi-walled carbon nanotubes (CNT) composites. The effect of ultrasonic amplitude and CNT concentration on processing characteristics, rheological properties, electrical conductivity and mechanical properties of both high (HPC) and low (LPC) PC filled with 0.2-1.5 wt% CNT was studied. Ultrasound showed significant effect on improving the dispersion of CNT in both HPC and LPC composites, as indicated by the increase of storage modulus at low frequencies, decrease of the rheological and electrical percolation threshold. Specifically, the rheological percolation of LPC composites decreased from 0.10 vol% for untreated samples to 0.055 vol% for treated samples at an ultrasonic amplitude of 13 æm. Meanwhile, the electrical percolation threshold of LPC composites decreased from 0.176 vol% for untreated samples to 0.088 vol% for treated samples at an amplitude of 13 æm. Additionally, obvious improvement in mechanical properties (including elongation, tensile strength, yield strength and Young?s modulus) of HPC composites after ultrasound treatment at 13 æm was observed. Finally, a possible mechanism of the decrease of both rheological and electrical percolation threshold by ultrasonic treatment was proposed.
Prediction of Failure in Foams Using Finite Element Method
Foams are widely used materials for light-weighting in various applications especially for the transportation industry. The mechanical properties of the foams depend on the cell morphology (i.e., shape and size) and volume fraction. Obtaining an experimental correlation between mechanical properties and morphology can be tedious and challenging. Developing a numerical methodology for predicting the mechanical properties especially the stress-strain curve of foams, can enable optimization of structures/morphologies for the required performance with lower resources.
In this paper, finite element method has been used to determine the stress-strain curve of foam including the ultimate stress and elongation to failure. Two cases, one without failure and the other with failure in the material model for simulation are presented. For both cases, a good correlation between the experimental and simulation was obtained in the initial elastic response and the plastic strain hardening regions of the stress-strain curve. Using the case with failure, the ultimate stress and the elongation at failure was predicted. It is found that the simulation over estimates the failure strain, mainly due to the way the failure model removes elements in Abaqus?. By making suitable changes to the code or to the failure threshold (calibration), prediction of failure in foam can be improved. The latter is illustrated in the paper.
Numerical Investigation and Experimental Validation for Wax Pattern Formation through Injection in Investment Casting
Lost wax process is widely used in metal casting to manufacture high precision products. However it covers lots of procedures, high precision quality is very difficult to obtain via conventional trial-and-error method. In this study, numerical method to simulate the wax pattern formation through injection molding in investment casting was proposed. To get better understanding, one hardware model is used to examine its shrinkage behavior numerically and experimentally. Through natural shrinkage and fixture constraint shrinkage study, the shrunk wax pattern dimensions and shrinkage percentage at various circular edges and location were measured. Simulation and experimental results are in good agreement. Specifically, the shrinkage difference between experiment and simulation is less than 1%. As the good control for the first step of wax pattern formation, it can further assist the shell formation and metal casting.
Numerical Simulation for Screw Geometry Design and Performance Effects on Fiber Breakage Study
Due to the high demand of smart green, the lightweight technologies become the driving force for people in automotives and others development in recent years. Among those technologies, using short and long fiber-reinforced thermoplastics (FRT) to replace some metal components can reduce the weight of an automotive significantly. However, the microstructures of fiber inside plastic matrix are too complicated to manage and control during the injection molding from screw, to runner, to gate, and to cavity. In this study, we have integrated the screw plastification, to injection molding for fiber microstructures investigation. More specifically, paid most of our attention on fiber breakage prediction during screw plastification. Results show that fiber breakage is strongly dependent on screw design and operation. When the screw geometry changed, even the compression ratio is lower, the fiber breakage could be higher.
Post Shrinkage Effect on Thick Optical Lens Development
This study investigates the geometric accuracy of thick fisheyes lens under injection molding. The effects on the geometric accuracy resulting from processing parameters in conventional injection molding (melt temperature, packing pressure, and filling time) and in injection compression molding (compression speed and compression distance) are studied in detail. First through simulations of Moldex3D, the relations between geometric accuracy and processing parameters are predicted. Then, the predicted results are compared with experiments. The comparisons show the trends in simulations and experiments are consistent. Nevertheless, there are discrepancies in quantities. To find the cause of the discrepancies, the re-heat phenomena after demolding are investigated.
Meeting Global Challenges with Micro Solutions: The Role of Plasma Surface Treatment in the Future of Plastics
The industrial landscape is ever changing. Some changes come from new discoveries and improvements; others are responses to problems and failures with existing methods. Still others are triggered by competitive market forces and demands such as lower cost. This paper examines seven global trends in plastic part manufacturing:
1. Greater use of regrind and recycled plastic resins
2. Increased interest in thin walled plastic parts
3. Continuous weight reduction in automotive
4. Growth of plastics with bright metal appearance
5. Further reduction in solvent use
6. More UV coating applications for plastics
7. Continued growth of medical plastics
Each of these represents new business opportunities as well as new implementation challenges. In particular we study the role that plastics? surface are expected to play in the success or failure of these new opportunities. We propose that plasma surface treatment provides a workplace safe, environmentally friendly, and cost effective means for meeting these new challenges.
3D Volume Shrinkage Compensation Method in Injection Mold Design Optimization
Injection molding is used widely in plastic production at present. However, how to optimize the manufacturing process will be the key to the product quality. To make the product development more successful and economical, CAE is essential to integrate instead of trial and error. Furthermore, warpage defect will cause more problems on the product accuracy or assembly directly. How to solve the warpage problem effectively is still in great demand. In this study, we have proposed ?3D Volume Shrinkage Compensation Method (3DVSCM)? to optimize the warpage quality. Specifically, we have investigated a mobile phone case systematically through trial-and-error method, industrial global compensation method, and 3DVSCM. Due to assemble purpose, there are twelve specifications needed to be satisfied at the same time. Results showed that using the trial-and error method, it is too difficult to keep all twelve specifications into the target. Meanwhile, using the industrial global compensation method with 0.48% compensation, it is still about 25% of specifications which are still not fit the target. However, using 3DVSCM, all twelve specifications can be fitted into the target easily. It will reduce the time and cost in product manufacturing process effectively.
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