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.
In cable industry, the ease with which a piece of jacket can be removed (stripped) from insulated multiwires is called strippability. A low stripe force is not only requested by customers and installers but it also makes the cable more flexible. The purpose of this paper is to present a method based on numerical approach to reduce the stripe force for a cable during extrusion. A correlation between the numerical parameter (pressure applied around the wires) and the stripe force measured on samples has been demonstrated afterwards it is used to design future extrusion pressure tooling.
Recent statistics on building fires show that smoke and toxic gases emitted due to burning of materials are much more harmful than the fire itself posing serious health hazard and sometimes fatal to the occupants1. It is for this reason, that many governing and regulatory bodies have laid Fire, Smoke and Toxicity (FST) standards for the use of plastics in public buildings and transportation in Europe, as well as the rest of the world. High-end engineering plastics like polysulphones are well known2 for their low smoke and flame retardance performance according to various standards, but their high cost could limit their use in certain areas of application. This work is an attempt to overcome these cost limitations by using an innovative technology and presents the development of a new poly(arylene ether) resin (PPE) based low smoke, flame retardant, halogen free, Noryl® NI-160 I OB resin (from here-on refe1Ted to as PPE+PS blend) that meets many of the FST requirements applicable to building codes and mass transit bodies in Europe and America. PPE resin is usually modified with polystyrene (PS) [ either crystal polystyrene (CCPS) and/or High Impact Polystyrene (HIPS)]. The PPE+PS blend utilizes a proprietary eco-friendly smoke suppressant technology that helps build robust char during its combustion. The robust char is believed to play a role in reducing smoke while maintaining outstanding flame retardancy and low toxicity. In addition, the PPE+PS blend offers advantages in terms of good proccessability, good mechanical and them1al properties, and low specific gravity.
The occurrence of two brittle ductile transitions is explained in terms of craze propagation and craze-crack transition models. The first and most familiar transition occurs at low temperatures and high strain rates and it is linked to chain scission. The other less well known transition occurs at elevated temperatures and low strain rates and is linked to molecular disentanglement. The importance of the entanglement network for these transitions is highlighted. The relation between these transitions and the molecular mobility transitions such as the glass transition and the -relaxation are discussed. Strategies for increasing the crack propagation resistance are reviewed. The present paper is taken from the authors’ feature article that appeared recently.
Aluminum has a high thermal conductivity which make them less suitable for window frames unless the inner and outer skin are separated by a thermal break. Currently glass reinforced Polyamide66 is used for this application. Noryl GTX* however has a thermal conductivity, measured on a extruded sample which is clearly below the thermal conductivity of Polyamide. Noryl GTX is also capable to withstand the high powder coating curing temperatures and meets the mechanical requirements for thermal breaks. By the upcoming, more stringent regulations on energy saving using Noryl GTX will help to meet these requirements.
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 phenomena, 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%).
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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