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.
High impact polypropylene (hi-PP) shows consistent growth rates, with the automotive industry being a main driver behind this. The fractionation of hi-PP into the individual components is essential to establish structure«property relationships. High temperature two dimensional liquid chromatography (HT 2D-LC), which couples a separation according to composition by high-temperature high performance liquid chromatography (HT-HPLC) with a separation according to molar mass by size exclusion chromatography (SEC) opens fundamentally new perspectives to characterise the molecular heterogeneity present in hi-PP. For the first time a separation of the amorphous EP rubber fraction according to its chemical composition becomes possible. The HPLC separation uses porous graphite as stationary phase and gradients of high boiling solvents as the mobile phase. Starting from the separation of EP model copolymers it is shown how commercial hi-PP can be chromatographically separated in a comprehensive way.
The loss of stabilizing additives is a crucial elemental step in the ageing of polymers. However, the approach currently used to determine the spatial distribution of antioxidants in finished or semi-finished products of polymers is extremely limited with regard to spatial resolution and reproducibility. Infrared microscopy offers an extremely powerful alternative with regard to both these criteria: Using infrared microscopy the extraction of the phenolic long term stabilizer Irganox 1010 from the wall of polypropylene pipes can be monitored. Carrying out IR-microscopy in a quantitative manner enables to determine the temperature and pressure dependent diffusion constants of the stabilizer. The same approach also allows to monitor the loss of Irganox 1010 from the surface of polyethylene pipes as a result of weathering. A quantitative relationship between the loss rate and the radiation dose can be established.
Trends in Automotive Lighting towards increased design freedom, weight reduction and lower system costs have resulted in an increased usage of thermoplastics. SABIC Innovative Plastics recently introduced its Lexan* XHT resin portfolio, a family of new transparent high heat polycarbonate copolymers. These resins can withstand elevated temperatures existing in close proximity to the light source and, as such, are suitable for usage in both metallized bezels and transparent lens applications. This paper will demonstrate the excellent metallization characteristics, weatherability and long-term color and property retention of these resins. Finally, other potential applications of Lexan* XHT resins will also be discussed.
A fast method was develop to predict the macroscopic properties of molded resin specimens tested in the Underwriting Laboratories (UL®) Relative Thermal Index (RTI) test (tensile strength retention) with microscopic properties that can be easily measured (molecular weight). By using higher temperatures than employed in the UL RTI protocol, accelerated ageing can be achieved in pellets. Polyetherimide (PEI) resin was spiked during extrusion with common stabilizers. The analysis focused on melt stability, rheology and long-term heat ageing performance. Hindered phenol stabilizers were detrimental under accelerated thermo-oxidative ageing of PEI. The use of new stabilizers should be carefully considered.
Polypropylene impact copolymers are widely used in automotive applications. They are required to comply with many criteria. Customers demand high-performance materials which also exhibit good aesthetical properties. The challenge is to balance properties as high impact strength, good flow ability and absence of surface defects, like tiger stripes. It is known that peroxide modification whilst increasing the flow ability of polypropylene impact copolymers deteriorates the basic mechanical and aesthetical properties. Work was performed in which a PP-impact copolymer was subjected to peroxide aided chain-scission under simultaneous presence of the co-agent 1,4- butanedioldimethacrylate (1,4-BDDMA). Results show that samples made with 1,4- BDDMA exhibit superior cold impact resistance and tiger stripe performance compared to the materials made with only peroxide. In addition, morphology, molecular weight distribution, and rheological behaviour of the continuous and dispersed phases of the modified PP impact copolymer were studied.
Lexan* copolymers offer new performance attributes in comparison to conventional polycarbonates by combining building blocks from different monomeric species. In doing so the application space of polycarbonates are expanded to include e.g. weatherability and scratch performance. By improving these attributes on an intrinsic level unique value propositions can be realized which include non-hardcoat or paint-out solutions. This can lead to cost-out opportunities and environmentally friendlier solutions. To emphasize application possibilities in the automotive industry, attributes are considered with regards to scratch, chemical and UV resistance for both Lexan* DMX and SLX resins.
Novel theory and methodology were developed to increase and intensify competitiveness and business activities of companies at plastics industry type SME. As result of research work the model for R&D – Tampere Model - was created. This model is based on four main components - research, networking, university-enterpriseco- operation and technology transfer. This paper describes the Model, its main results in economical and technological terms using a Finnish SME, Vesita Ltd., as business case. The process has developed the company and its business from small local to research orientated and international. This has also led to new hightech products and increasing use of plastics components.
Many producers of large technical parts are struggling with increasing demands for short-run parts, caused by a trend toward differentiation (more SKU’s), Just In Time (JIT) delivery and multiple colors for consumer appeal. With many large technical machines requiring as much as 8-12 hours of running to switch colors or materials, this is a huge cost and profit drain on processors. This technical paper illustrates the necessary key elements in large part blow molding to tackle these supply chain requirements. It discusses current limitations, and advances in machinery design to enable fast resin and color changes in large industrial machines.
This technical paper illustrates the current state and applications for multilayer containers that package food and consumer products. The paper describes different structures utilized in making containers for varying applications, including demanding barrier requirements. We also discuss how to meet requirements for food processing systems, including hot fill, pasteurization, and retort. Several case studies of multilayer containers currently in the market are shown. The paper includes pictures and diagrams and is designed to serve as an ongoing guide for anyone tasked to determine appropriate container manufacturing processes, container designs, and material configurations to meet various barrier and post-filling requirements.
Strain softening in semi-crystalline polymers, is one of their most important viscoelastic characteristics and these materials are very sensitive to temperature and strain rate. A new phenomenological model with strain, strain rate and temperature dependence on stress was developed based on the Gsell & Jonas model with a new expression used to predict the strain softening henomena, completing the whole mechanical behavior of polymers from initial strain, strain softening and part of the strain hardening. Model verification was performed on four materials and it was developed to further study the complex deformation patterns in thermoplastic materials subjected to impact loads
In recent years, injection molding technologies have been developed which use variable mold heating and cooling to increase part quality without significantly increasing cycle time. These processes are not suited for simulation with a conventional steady-state (cycle-average) mold thermal analysis. This paper presents the development of a new 3D finite element based transient mold cooling simulation capability which includes coupling the mold thermal solution with the mold filling and packing simulation. The predicted transient mold temperatures are validated against measured mold temperatures for two instrumented injection molding trials.
Nanoclays have to intercalate and exfoliate. The extent of intercalation and exfoliation is not understood by the processing industry. Researchers have to develop and nanoclay manufacturers have to supply a product which can intercalate and exfoliate to achieve the desired performance of the final product. The nanoclay powder which is supplied has a BET surface area of 5m2/gm or less. To disperse such a powder from 5 to 750m2/gm is difficult. To salvage such a situation, there has been a relook at minerals which are platey such as talc and mica. The finest talc supplied in the world has a BET surface area of 15m2/gm. It is possible to further grind this talc (also mica) along the basal cleavage to 100m2/gm to 200m2/gm. Such talc, if added to polymers can improve properties.
The substitution of plastic for more traditional materials stems from its reliability and affordability. However, with the heightened awareness on sustainability, plastic from fossil sources are sometimes perceived to adversely impact the environment. In an effort to address this issue, a detailed life cycle assessment of heavy duty sacks made from metallocene polyethylene (mPE) has been completed. The sacks are used in packaging powdered products for the construction industry. The results show that these sacks have several positive attributes and in many instances, may be a preferred alternative from a sustainability perspective. In fact, in manufacturing, transportation and handling mPE sacks are shown to consume significantly less energy and emit less greenhouse gas than paper-based alternatives. Additional environmental benefits will be discussed.
The objective of this paper is to discuss unique part and mold design requirements for high volume, cost competitive compression molding of carbon fiber reinforced epoxy (CF/E) uni-directional prepregs (UD). The typical part and mold design for compression molding of chopped fiberglass reinforced polyester sheet molding compound (SMC) will be used for comparison. Information that can be used as a design and processing guide for composites engineers involved with the development of high stiffness and strength CF/E for application in the transportation industry will be shared.
Polymaterials has developed a new high-throughput compounding (HTC) technology which generates thermoplastic formulations and DIN-ISO compliant test specimen accepted by engineers and the plastic industry. This technology accelerates the development of new compounds and is also much more cost-effective since only a fraction of material and time is needed compared to the conventional process. HTC not only increases the output significantly but also generates more insights enabling one to push innovation and to cut time to market for new products. The presentation introduces the technology and illustrates its capabilities by demonstrating several case studies.
In this study composite materials based on highdensity polyethylene (HDPE) with fillers containing nanostructures were prepared using melt mixing. Vapour Grown Carbon Fibers (VGCF), multiwalled carbon nanotubes (MWCNT) of the types Baytubes® C150P and NanocylTM NC7000, anthracite powder, microsilica, organoclay and expanded graphite (EG) as well as mixtures of these fillers were used. The amount and mixing ratios of the hybrid filled systems have been varied to determine the effect on the achievable level of thermal conductivity as measured on pressed plates. The filler dispersion and phase adhesion were studied using scanning electron microscopy. When limiting the maximum filler content to 10 wt%, the highest enhancement in thermal conductivity by 166% was found for VGCF followed by a 1:1 filler combination of VGCF with EG (148%).
Long fiber thermoplastic (LFT) composite design studies often emphasize fiber content but are sketchy on fiber-orientation, fiber-matrix interface and mold design. In this paper we detail a comprehensive approach to designing with LFT materials. Specific examples are given. Carbon-fiber compounds were successfully substituted for die-cast magnesium parts by redesigning the metal part for injection molding. Tailored fiber architectures were achieved through strategic gate locations, as advised by Finite Element Analysis (FEA) and Mold Flow Analysis (MFA). Mechanical properties were enhanced through modified molding processes.
The use of pulsed cold water instead of tempered coolant is suggested to be a versatile and cost-efficient technique for the cooling of injection moulds. However, the advantages and limitations of such discontinuous cooling strategies are still a controversial issue. In this paper the behaviour of a discontinuous temperature control system is analysed with a particular focus on the reproducibility of the process and the realisable dimensional stability of the parts and compared to that of a continuous cooling. For the investigations both a conventional and a conformal cooling channel geometry are considered. It turns out that at high mould temperatures the warpage of the parts can be reduced by use of discontinuous cooling, but at the same time the reproducibility of the process is affected adversely. The regulation of the discontinuous cooling proved to be challenging especially in combination with conformal cooling.
Weld lines are formed during injection molding, when two flow fronts meet. They are often not avoidable in complex technical parts. Their presence reduces mechanical strength, especially in high performance short fiber reinforced materials. Evaluating the load of highly stressed parts requires accurate knowledge of the interrelationship between the type of weld line, its morphological structure and the resulting mechanical properties. This paper aims at the development of a simulation method which enables the mechanical properties of weld lines to be considered precisely in part design.
The plastic parts for a float-valve system were designed. In the design was considered the use of PET bottles as floating device instead of the regular spheres, in order to promote the reuse of this plastic container and to decrease plastics residues. Additionally, the part thickness was reduced to use less plastic on the parts, and to decrease cycle times. All molds are two-plate and two cavities. The refrigerating system proposed uses U-shape channel, and the expulsion system is composed by ejector pins. Threaded connector´s mold is more complex due to require two-step opening.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
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