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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Corissa K. Lee, Jericho L. Moll, Paul A. Ledwith, Steven B. MacLean, May 2015
Acrylonitrile butadiene styrene (ABS) tensile specimens produced by 3D printing in two different orientations, injection molding, and subtractive machining were fractured by tensile overload in accordance with ASTM D638. In this study, the tensile properties and fracture surfaces of the different manufacturing methods are compared and contrasted using optical microscopy, computed tomography (CT) and scanning electron microscopy (SEM). CT reconstructions of the pre-failed tensile bars and images (optical and SEM) of the fracture surfaces are provided and discussed.
Jake Behrens, David Grewell, James Schrader, May 2015
Compounds of soy flour, biochar and a polymer matrix, such as PLA, have proven to be effective fertilizers comparable to commercial products. Prototype composites achieved NPK values of 2.85, 0.20, 0.49 and 3.08, 0.21, 0.48 %, respectively for PLA- and PHA-based composites. These composites only leached a fraction of nitrogen compared to a commercially available synthetic fertilizer. Low leachate values, as compared to commercial fertilizers, may be associated to the absorption and releasing of nutrients by biochar. The nitrogen within the soy is also not readily water soluble and is released over time by microbial action.
The relationship between the degree of crystallinity and the ultrasonic velocity was analyzed in this study for injection molded poly(lactic acid) (PLA) parts undergoing an annealing process. An annealing process was first employed to produce PLA parts with different degrees of crystallinity. Next, a novel ultrasonic water immersion method was presented for calculating the ultrasonic velo?cities of these annealed PLA parts. Then, the ultrasonic velocity results were plotted with the crystallization re?sults from differential scanning calorimeter (DSC) mea?sure?ments for analysis. Experimental results show that the inverse effective ultrasonic velocity versus the degree of crystallinity over the whole crystallinity range for three different annealing temperatures show good linearity, with a correlation coefficient of around 99%. The linear rela?tionship observed in this study might provide a novel method for investigating the degree of crystallinity of semi-crystalline polymers in practical production.
In this work, we have studied the electrochemical behavior of non-porous and porous nano-graphene/polyimide composite films fabricated by the thermal degradation of grafted flexible acrylic acid on polyamic acid backbone. It is observed that pore size distribution has a significant effect on specific capacitance and bulk resistance of the composite material. BET and Electrochemical impedance spectroscopy (EIS) data reveal a complex pore distribution for the materials. As the porosity of the composite material increased, its bulk resistance decreased by up to 400% and the specific capacitance increased by up to 200%. Ionic diffusion resistance associated with the pore structure for the porous composite decreased due to easy access of electrolyte ions through the pore length of the material. Specific capacitance of up to 34,240mF/g was obtained for the composite system at a scan rate of 50mV/s which remained fairly stable through the 50 cycle runs. Potassium hexaflorophosphate (KPF6) dissolved in propylene carbonate was used as electrolyte for all the electrochemical techniques.
Miguel A. Hidalgo, Jos‚ H. Mina, Tim A. Osswald, May 2015
In order to design and manufacture natural fiber-polymer composites as structural components in existing and novel technological applications, the long term viscoelastic behavior of the materials must be understood. In order to do that, the time?temperature superposition principle (TTSP), is used to predict long-term viscoelastic behavior from short-term experimental data. Dynamic?mechanical analysis (DMA), was used to study the viscoelastic properties of composites made from fique mats and low-density polyethylene?aluminium (LDPE?Al) obtained from recycled long-life Tetra Pak packages. This paper reviews the effect in using Chemical treatments such as alkalinization with NaOH, silanization, and polyethylene impregnation treatments for composites, understanding the interaction mechanisms between natural fibers and the LDPE-Al; and presents the effects of treatments on the viscoelastic behavior. Fractographic evaluations in the scanning electron microscope (SEM) confirm the quantitative characterization obtained from DMA.
Polymer based thermoelectric materials were usually fabricated using solvent casting methods in the past. However, such processes may involve the usage of highly toxic solvents and solutions. In this paper, we present the results of thermoelectric performance of poly(vinylidene fluoride) (PVDF) based thermoelectric material with graphene nano-platelets (GNP) and multiwall carbon nanotube (MWCNT) as fillers. The samples were fabricated though melt blending method, which is a cheaper, simpler process and can be easily scaled up to industrial level for mass production. Our results indicated that melt blending process can produce either similar or superior results compare to the traditional solvent casting methods. For GNP/PVDF samples, we have found a superior Seebeck coefficient approximately 200% higher compared to the value reported from previous studies, while the electrical and thermal conductivity show similar values. In addition, our melt blended MWCNT/PVDF samples showed a similar trend comparing to solvent casted samples that were reported in literature.
Heat Treatment is defined as the controlled heating and cooling, of metals, in order to alter their physical and mechanical properties.
First, before the mold is designed, the Engineering department reviews the quote then employs proven methods of design, material selection, and heat treatment.
This understanding is the key to selecting the best material, for a particular component. Additionally, the ability to specify this, to your outside services, will provide the end result you desire.
All Engineers do not have metallurgy knowledge, therefore, the heat treatment processes defined below will include some of the language used by a Metallurgist. This will help when specifying treatments, on mold design components, and to better relate to the processes used.
When designing injection molds, many decisions are made while quoting. Parts are examined for entrapment or details that cause them. Solving entrapment issues requires creative undercut solutions. There are many undercut solutions offered today. The designer needs to know how to quickly select the correct option for the most efficient molding and tool building.
This paper addresses methods of releasing threads, snaps, hooks, holes and anything that has a mechanical action that must take place before a part can be ejected and the mold opened. Often a certain method is used for a mold that is traditional, but with a fresh look at the part and current solutions, the design can be simplified. This can result in lowering molding time, manufacturing time and ultimately cost.
This informative guide addresses the most common undercut conditions with simple and long-lasting solutions. It compares traditional methods to non-traditional methods and explains the advantages and disadvantages.
Lun Howe Mark, Guilong Wang, Chul. B. Park, Ungyeong Peter Jung, May 2015
Using gas-assist in conjunction with foam injection molding has the potential of creating a highly synergistic production technique. By combining two supplementary processing strategies, weight savings with higher quality cell morphologies can be achieved. In this study, the effects of gas-assist processing parameters were systematically examined on the cell morphology of TPU. These gas-assist parameters include the holding time, holding pressure and start delay. The cavity pressure for different gas-assist pressure profiles was also examined.
Cellulose nanofiber (CeNF) is generally provided by micronizing a plant fiber to a nanometer-size in diameter. A CeNF reinforced thermoplastic composite is recently expected to indicate integrated high performance concerning light weight, thermal resistance and mechanical strength. It is important to disperse and defibrate CeNF uniformly in a resin in the extrusion process. In this study, various compounds of microcrystalline cellulose (MCC), CeNF, PLA, and PP were made using additives by the extrusion process. The mechanical properties were also evaluated.
Modern inorganic pigments are no longer just colorants for visual appeal; rather, they are functional colored materials exhibiting a wide range of properties. This distinction is important as pigments now provide specific physical and chemical advantages in addition to bright colors. It is therefor important to understand the fundamental correlations between crystal structure and physical properties when designing new pigments. New research pushes the boundaries of traditional metal oxide pigments by utilizing unusual host lattices, new elemental combinations, and unique synthetic methods. This paper will establish the basic considerations of modern pigment design and discuss the recent advancements in blue pigments, namely in the YIn1-xMnxO3 family.
In Japan, eggs are widely used in many food products on the market, and 200,000 tons of eggshells are annually discharged and most of them get discarded. Re-use of discarded eggshells into food trays is one of the efficient ways to realize a recycling-oriented society. Many food trays consist of polypropylene or polystyrene, and sometimes recycled products. Thus, it is possible to use biomass materials such as eggshells as a bulking agent. Eggshells need to be compounded into resin when used in food trays, but the egg?s unique sulfur smell is emitted when applying heat in the manufacturing process. In order to solve this odor problem, we compounded under different conditions with polypropylene and eggshell to research ways to reduce odor. The results suggested that molding temperatures exert significant influence on odor generation. By molding at the lowest temperature that enables resin to mold, a possible countermeasure for odor reduction is created.
Fiber-reinforced composites assume a key function in lightweight design. Due to high material and manufacturing costs, the objective is the near net shape manufacture of composite components via the forming processes. Subsequent cutting processes such as deburring are, however, still necessary. This post-processing leads to a reduction in the mechanical properties, not only through the cutting of the continuous fibres but also through potential production-related damage. The excellent durability properties of fiber-reinforced composites are thus lost. In this paper it is assumed that the production-related reduction in the mechanical properties of composites with thermoplastic matrix is not only caused and influenced by the design of the machining process but also through the method of clamping the parts which is necessary during the process. The qualitative evaluation is done through microscopical determination of the surface damage and the inter-laminar damage through ultrasonic inspection. Following an accelerated ageing process under the influence of bending loads, the determination of the flexural strength is carried out.
Current lightweight composite solutions demonstrate their technological feasibility by using lightweight material. The whole lightweight potential of composite parts, however, can only be used in combination with lightweight design principles. There is a limitation in creating lightweight optimized applications. The manufacturing technology must achieve both, economic process with low cycle times and high process integration.
The article gives an overview of material lightweight and structural lightweight design of continuous fibre reinforced thermoplastic composite applications. Furthermore new process technologies for present automotive applications are shown (bumper systems, seat structures) which integrate structural and material design in a One-Shot-Process. The key benefit of the Technologies, beside the lightweight potential of the used materials and design, is a short cycle time (less a minute) that can only be realized due to using thermoplastic composites and a process integration/combination. Therefore these processes are ready for implementation in mass production.
Selective laser sintering (SLS) of polymer powder is readily used for the additive manufacturing of plastic parts. During SLS processing a laser is used to fuse powders together to form whole parts. The build direction, which corresponds to the axis on which the longest dimension of the part is oriented, can greatly influence the morphology and material performance of the final product. In this study we evaluate the microstructure and mechanical behavior of SLS processed polyamide 12 (PA-12) as a function of build direction.
LORD offers adhesive solutions that effectively bond plastics to substrates directly in an injection molding process. A specially designed injection mold was created to evaluate adhesive technologies and their effectiveness in bonding various thermoplastics, such as nylon, polycarbonate, PC/ABS, and TPU?s, to substrates such as aluminum and glass. This paper focuses on in-mold bonding of PC, PC/ABS, and nylon 66 to aluminum. Molded assemblies were tested for adhesion directly after molding and after environmental exposures (thermal cycling, heat and humidity, and anodizing). This process and product technology offers a number of design and cost benefits, such as light weighting, design freedoms, and manufacturing efficiencies.
Injection molding, a typical batch process with two-dimensional (2D) dynamics along the time direction as well as batch direction, is a widely used polymer processing technology transforming plastics into products of various shapes and types. Despite of fast development of hardware, computational load has to be considered in injection molding control system. Meanwhile parameters of control algorithm should be easy to tune and separately relative with control performance like set-point tracking and disturbance rejection. In this paper, a fast and effective 2-dimensional (2D) control algorithm combining model predictive control (MPC) and 2D error prediction is proposed based on the characteristics of injection molding processes, all parameters are normalized within 0 and 1, and separately related to control performance. The proposed control scheme is tested experimentally through the closed-loop control of a key process variable, packing pressure. The result shows the good performance and verifies the previous designs.
During the extrusion of polymers, it is generally necessary to provide heating and cooling capabilities at the extruder barrel for start-up and temperature control during operation. The most common solutions used, are electric resistance heaters in combination with air-cooling by radial blower fans. These heaters are usually grouped in zones to allow the setting of temperature profiles along the barrel. Although this well-established solution benefits from several of its properties, there is one major disadvantage. At certain operating points, it is unavoidable that cooling is applied to keep the processing temperature within the given limits. By the use of air-cooling, the extracted heat is wasted and the energy efficiency of the extrusion process decreases.
The main goal of the presented approach is to preserve this extracted energy inside the system and make it utilizable at another location in the process. This is achieved by a fluid heating system using thermal oil as heat transfer medium. The system provides two global temperature levels of thermal oil and uses bypasses for each zone along the barrel of the extruder. These bypasses allow the setting of a specific desired feed temperature for every single zone without the requirement to provide an independent fluid heating system respectively. The return flow is distributed back to the global fluid streams based on the fluid temperature after the zone. Depending on the specific operating conditions, this distribution leads to a decreasing power demand of the complete temperature control system by utilizing extracted process heat to minimize the additional global heat requirement.
Qi Li, John P. Beaumont, Alicyn Rhoades, John P. Coulter, May 2015
Runner based shear imbalance has been existed since the beginning of the related polymer injection molding development. The major phenomenon of the shear imbalance is the non-unique filling results in the molding cavities, even if the cavities are balanced in space and position. Researchers have been studying the shear imbalance problems, such as shrinkage or warpage, and the associated solutions for years. However, there is not such a solution that could be universally accepted by all industries or research academies. In some previous studies, a novel technology, Melt Rotation Technology, has been studied and developed theoretically and experimentally, providing persuasive evidence that the melt flow shear gradients developed in the runner system during traditional injection molding process is mainly responsible for the imbalance filling results, and Melt Rotation Technology was able to overcome the shear induced problem and modify the thermal, physical or mechanical properties of the molded specimens. In the current study, polymer samples molded with and without Melt Rotation Technology were tested and compared logically. Specimens from higher shear melt flow regions exhibited higher crystallinity as well as higher melting temperatures due to the localized shear rate variation. New molding trials were implemented and more experimental results have been found to support the effectiveness of Melt Rotation Technology.
In this research, direct fiber feeding injection molding (DFFIM) technique was used to produce PC/ABS/PC oligomer blends composites reinforced Glass Fiber. The continuous roving of glass fibers were fed into the vented barrel directly and mixed with matrix. The number average fiber length of 10 wt% oligomer composite is longer than that of 0 wt% oligomer composite. Oligomers reduce viscosity of matrix, fiber attrition is reduced. The tensile strength of specimen containing oligomer is limited by about 115 MPa in case that fiber volume content is over 12 %, because increasing amount of fibers is facilitated attrition of fibers. From observation of scanning electron microscope, interfacial adhesion is poor, because of gap between matrix and fiber. The effect of oligomers is nothing to tensile properties.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.