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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Simulation and Validation of Mold Filling with Velocity Controlled Valve Gates
Part surface defects can be prevented or minimized by using a cascade molding process with valve gates opening sequentially at controlled speeds. The process dynamics of cascade injection molding were investigated and simulated in the Autodesk Moldflow Insight (AMI) simulation software. Molding trials were performed with sequential valve gates opening at full speed and at variable speeds, respectively using Synventive hot runners equipped with SynFlow?. The experimental results were compared with the predicted results from the simulation software and good agreement was obtained.
Deformation Measurement, Modeling and Morphology Study for HDPE Caps and Closures
Compressive strain data of as-is closures are obtained as a function of time and stress using a modified probe in a DMA instrument at 930C. Data are modeled using a strain equation which involves stress exponent and time exponent. The model describes the data obtained from different types of closures made of high density polyethylene (HDPE) and polypropylene (PP) very well. It is also in line with what is expected for deformation resistance regarding the molecular weight and density of HDPE and type of polymers (PP vs. PE). In addition, the predicted compressive creep data agree well with field observations on two HDPE closures. The tendency of the deformation of these two HDPE closures might be related to their crystallization rates and crystalline structures. The methodology may be useful to provide a rapid and cost-effective means for closure deformation prediction, resin comparison on the same closure design and correlation with some end-use closure properties in a sealed system.
Verification of a Structural Analysis of Fiber Reinforced Thermoplastics with Weld Line
Finite element methods are a powerful tool to determine mechanical properties of injection molded parts prior to start of production. However, it is still a challenge to predict the weld line quality of a fiber reinforced thermoplastic precisely. Thus the verification of simulation results is necessary to tap the full potential of lightweight materials. In this study the verification of a structural analysis was split into three minor objectives in order to better understand what affects a weld line:
In this study the verification of a structural analysis was split into three minor objectives in order to better understand a weld line:
(1.) Influence of process parameters on the mechanical properties of weld lines
(2.) Influence of glass fibers on the mechanical properties of weld lines
(3.) Verification of a structural analysis regarding breaking stress and fiber orientation and length distribution
A design of experiments (DoE) was used to carry out injection molding dependent effects. Therefore, two gated tensile bars where molded to induce a weld line and then analyzed with a tensile testing machine. The analytical methods of fiber length scanning and æ-CT were used to verify the fiber-length distribution and the configuration of the fiber orientation in the weld line. The experimental results were then compared with the results of the simulation.
Six Sigma Methodology for Solving System Wide Issues and/or Methodical Solutions to Individual Quality Issues
The Six Sigma methodology is generally used for a Management sponsored, disciplined, team based approach to find solutions to system wide issues of vital importance to an organization such as low or no profits, chronic quality deficiencies, missing delivery schedules, etc. While an organization may or may not choose to use Six Sigma to improve a system wide issue, individual tools within the methodology can be used to systematically fix issues on specific products or processes. Some of the more common tools are Pareto Analysis, 5 Whys. Fishbone Analysis, FMEA and Design of Experiments, to name a few. This paper will use selected case studies to highlight the proper use of some of these tools.
Bio-Based Aliphatic Epoxy Clay Nanocomposites
The focus of the present research is the development of a new family of bio-epoxy nanocomposites for coatings and other high performance applications. A sorbitol glycidyl ether (SGE) epoxy resin has been cured with two different aliphatic polyetheramines: a poly(ethylene oxide) diamine (PEO) and a poly(propylene oxide) diamine (PPO). The degree of dispersion of commercial organo-montmorillonite clay (Cloisite 93A, C93A) was assessed optically in both the neat resin components and cured films. In general, the compatibility of the polyetheramines with the nanoclay was found to be good. While this would seem to imply enhanced dispersion, in practice it is well-known that poly(ethylene oxide), for instance, will intercalate but not exfoliate montmorillonite layers due to its inability to screen interactions between adjacent layers. Curing behavior of all samples was followed by Near-IR (NIR) spectroscopy. The extent of epoxy conversion is very high for SGE/PEO and SGE/PPO networks. The effect of the C93A in the systems is related to interactions between the curing agents and the clay modifier as well as the silicate layers themselves. When C93A was added to the systems, a slight enhancement in the rate of epoxy-amine conversion was observed prior to gelation in the SGE/PPO system as compared to the SGE/PEO system. Consistent with greater levels of dispersion in the neat resin, this may imply that the resin components have greater access to the clay modifiers, which are known to have catalytic properties in epoxy polymerizations, resulting in a greater degree of polymerization within vs. outside of the interlayer galleries. In order to quantify these effects, gelation times were studied by viscosity measurements. Consistent with the aforementioned arguments, shorter gel times were detected in the SGE/PEO compared to the SGE/PPO system. In addition to cure kinetics, mechanical properties were also studied. The SGE/PPO/C93A system displayed a larger increase in Young?s mod
Cellulose Acetate as a Tunable Bio-Based Engineered Material
Cellulose acetate (CA) is one of the oldest plastics, with an application history dating back over 100 years. Recent drivers towards an engineered bio-based material that can be used in demanding applications have caused revitalization in CA product development. This paper illustrates the ability to fine-tuning mechanical and thermal properties through plasticizer selection. A case study is also presented where CA can be used to enhance the bio-content of the petro-based plastics such as polypropylene (PP) while improving performance of the final blend.
Effect of Process Variables on Pigments Dispersion in a Polycarbonate Based Compounded Plastic
Three input variables to the extrusion process - temperature, screw speed, and feed rate, are investigated for their impact on colour pigments dispersion vis-…-vis plastics coloration. Pigments dispersion is quantified using scanning electron micrography and image analysis. A correlation between processing conditions and distribution graphs for pigments particle size and inter-particle distance is discussed and compared with colorimetric data. The results obtained through these investigations could help plastics compounders achieve consistency in output colour of plastics.
Comparative Evaluaiton of Commercially Available Nucleating Agents in Polyamide 66 Formulations
Nucleating agents are frequently applied to improve crystallization rates in the efforts of improving processing times and properties. This study evaluates the efficacy of various commercially available nucleating agents such as zinc compounds, mica, talc, boron nitride, and mixes of organic & inorganic compounds in polyamide 66 (PA66) formulations. Thermal analysis through DSC was performed on unfilled and glass filled formulations for various loadings of nucleating agents. The data presented in this study compares the initiation of crystallization and crystallization peak temperatures to determine the effectiveness of these processing aids. Particle size and structures of the nucleating agents are then analyzed to correlate with the observed results. Effect on impact properties as a consequence of higher nucleation rate is further explained.
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.
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