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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Asymmetric Conductive Heat Transfer Resulting from Air Gap Formation during Shrinkage
In injection molding processes, an air gap is formed between the cavity steel and plastic part as shrinkage occurs throughout the cooling phase. Considering the significant difference between the thermal conductivity of P-20 steel (41 W/m·?C) and air (0.0383 W/m·?C), the air gap is a potential medium for creating an asymmetric conductive heat transfer within the plastic part. This assumption of different heat transfer behavior was studied by using finite element analysis and flow simulation packages. The results were contrasted to those of the symmetric behavior. The conclusions made discuss the practical needs of considering the air gap formation in cooling designs and its probable impact on qualities of plastic parts.
At-Process Spectroscopy and Ultrasonic Monitoring of Polymer Melt Processing for Process Monitoring and Control
The use of spectroscopic techniques in the analysis of polymer production processes is becoming more prevalent. At-process methods allow for real-time information on a variety of melt characteristics to be collected. Several analytical techniques are being explored for in-line and on-line use during extrusion processing of polymer melts, with a view to characterising polymers for process monitoring and control.In-line ultrasonic velocity measurements have been made simultaneously with on-line mid- and near- infrared and in-line Raman Spectroscopy during single screw extrusion of a range of blends of an HDPE and a PP. The sensitivity of these techniques to changes in blend composition is being assessed and compared. The techniques show very close agreement in monitoring the dynamics of change from one blend composition to another.
Automated Sheet Die Design
This paper reports on a method of integrating extrusion die design with state-of-the-art computer-aided design programs. The design of a coat hanger extrusion die is automatically optimized using a parametric based three-dimensional polymer flow simulation algorithm. The optimal parameters determined by the optimization algorithm are input to a parametric-based computer-aided-design program to yield tool path for die fabrication. A prototype coat hanger die is fabricated according to the material selection and process conditions specified. Experimental flow distributions match the predicted flow distributions within acceptable experimental error. Because this approach employs three-dimensional flow analysis, it can readily be extended to profile die design.
Automotive Requirements for DuPont Engineering Polymers in Integrated Air Fuel Systems
Automobile companies are looking with increasing frequency at composites (engineering polymers based matrix) to reduce weight, cost and to improve the recyclability of their powertrains.Air Intake Manifolds (AIM's) and Integrated Air/Fuel Systems (IAFS) have emerged as prime candidates for conversion from metal to composites and market penetration in North America is above 80%.This paper will present the state of the art for materials in these applications including real life examples and analysis.Also we will share some of DuPont new offerings in these market that provide significant system cost reduction while performing better in a more demanding environment.
Ballistic Impact Resistance of Composites with Different Fabric Structures and Configurations
Ballistic performance of fiber-reinforced composites with different fabric structures and configurations was studied. Composites with Kevlar-KM2 ripstop fabric performed better against smaller size projectiles due to the effective fiber failure through constraining of the fibers, while hybrid composites constructed from ripstop fabric of Kevlar-KM2 and Spectra-1000 show an advantage with larger projectiles due to the effective strain energy absorption. Hybrid composite configuration of these two structures exhibited overall performance improvement.
Basic Mechanisms of Structural Ordering in Uniaxial Stretching of PLA Using Fully Automated On-Line Birefringence Coupled with True Stress-True Strain Measurement
Fundamental deformation-structure relationships in melt cast amorphous Poly(lactic acid) (PLA) films were investigated using a stretch birefringence apparatus that allows for direct measurement of true stress, true strain, and birefringence at realistic strain rates. The relationships between stress, strain, and birefringence are strongly affected by the processing conditions: temperature, stretch ratio, and stretching rate. The molecular mechanisms of this deformation and the effects of process variables on these are elucidated in this study.
Basic Principles in Materials Selection for Mechanical Fastening of Thermoplastics
In this current paper, we are discussing basic principles in materials selection, which focused on utilization of the light alloys for manufacturing of fasteners for thermoplastics applications.Proposed fastener(s) material replacement (from steel to aluminum) will allow to manage the stiffness considerations, short-term (strength) and long-term (life) performance of the assembled plastic parts for various automotive applications.The results from this investigation provide recommendations on materials pre-selection for the design of fastened thermoplastic components with improved mechanical performance.
Basic Screw Geometry Things Your Screw Designer Never Told You about Screws!!""
In the plastics industry today and as has been since the start of plastic extrusion, the end user has depended on the Original Equipment Manufacturer (OEM) and/or screw manufacturer to supply them with the proper screw design for their material and process. Most processors have learned over the years a few critical points pertaining to screw design, but never totally understanding the reason why their suppliers have recommended certain aspects to the screws that they have purchased. Hopefully, this paper will explain some of the basic knowledge needed in order for an end-user to make the proper decisions when using or purchasing a new single screw for a smooth bore application.
Basic Studies on Uniaxial Deformation of Nylon 6 - Clay Nanocomposite Films
The changes in the birefringence and the true stress-true strain behavior of cast nylon 6 and nylon 6-clay nanocomposite films are monitored online as they are stretched uniaxially below the peak melting temperature. The effects of draw temperature (100°-140°-180°C) and clay content (2 and 5 volume%) are investigated by means of online measurements and X-ray diffraction. The presence of nanoplatelets in the nylon matrix enhances the uniformity of stretching by suppressing the localized necking behavior at these essentially cold drawing temperatures. At a given stress, the birefringence decreases as the clay content increases. This is quite interesting and perhaps is related to reduction of structural connectivities by reducing the polymer entanglements in the presence of these very small nanoparticles. The development of birefringence correlates well with the strain rather than the clay content or the stretching temperature. The crystalline phase of the as-cast films is ?-form. Stretching promotes the formation of ?-crystals at all draw temperatures for nylon films. At low draw temperatures, the nanocomposite films also assume ?-phase, while at 180°C they display a mixture of ? and ? phases.
Biaxial Stretching and Structure of Various LLDPE Resins
The purpose of this study is to investigate the biaxial stretchability, the structure developed, molecular orientation and shrinkage of linear low-density polyethylenes (LLDPEs) biaxially stretched using a laboratory biaxial stretcher. Seven resins having different molecular characteristics were used in this study. The effect of stretching temperature and rate on stretchability is assessed. Biaxial orientation factors for the crystalline axes as well as that of the amorphous phase were determined using FTIR spectroscopy. SEM was used to reveal the details of the crystalline stacking and shrinkage of the films was determined.
Blends of Polypropylene (PP) and Polycarbonate (PC) Using Functional Polyolefin Elastomer (FPOE) as a New Compatibilizer
Polypropylene (PP) and Polycabonate (PC) is an immiscible polymer pair. When blended together, it separates into two phases. It generally yields poor practical properties. The final morphology of the blend has a controlling influence on its mechanical properties. In this study, Functional Polyolefin Elastomer (FPOE) is used in the blends of Polypropylene (PP) and Polycabonate (PC) as a compatibilizer to control the morphology and to strengthen the interfaces in this blending system. With addition of FPOE, the size of PC domains is reduced and interaction between different phases is greatly improved. The mechanical property of the blends with FPOE, such as impact strength, is significantly improved. FPOE can be applied for the blending of PP and PC as a new effective compatibilizer [1-8].
Blocking of LLDPE Films - Effect of Surface Morphology
The mechanism of LLDPE blown film blocking has been investigated. Film specimens exhibiting different levels of blocking force were fabricated using resins with various molecular characteristics. The film surface morphology and the chemical composition were studied. Atomic Force Microscopy observations allowed to link clearly blocking with the formation of a soft layer at the films interface. This layer is made of amorphous PE chains, migrated from the bulk of the film during conditioning at 60°C. No evidence of co-crystallisation at the interface was observed. The chemical nature of the soft layer has been derived from its mechanical properties. A predictive model for film blocking is proposed based on a single molecular parameter.
Blown PP Based Coextruded Films as an Alternative for the Flexible Packaging Industry
New PP resins are available in the market allowing for the production of coextruded or monolayer blown films with particular properties. Some advantages are associated with lower resin densities and higher modulus in comparison with other commodity resins. Currently, PP also has a significant price advantage in many market. High stiffness and high clarity can be achieved when PP is coextruded with PE, allowing for thickness reduction depending on the final application. This paper presents a comparison of mechanical and optical properties among structures using different polypropylene resins and different layer thickness.
Capacitive Sensing Dielectrometers for Noncontact Characterization of Adhesives and Epoxies
Recently developed capacitive sensor geometries provide new capabilities for characterization and manufacturing quality control of low conductivity dielectric materials. Novel geometries incorporating multiple sensing elements within a single footprint permit profiling of the properties with depth (such as dielectric constant, conductivity, loss tangent, complex permittivity and layer thicknesses) from one side of the material. These sensors permit absolute property measurements with minimal calibration requirements and noncontact measurements where the air-gap thickness is also being measured. This paper reviews the sensing technology and its use in cure monitoring of epoxies and adhesives in thick and thin film applications.
CAPE-VIT - A Different View of Education in Plastics Design
Education for the growing needs of the plastics industry is recognized as needing a different approach that will enable a quicker integration of the graduates in the working world. Under the auspices of the EU programme Leonardo da Vinci a group of universities and institutions developed a course programme and structure for preparing engineers with skills for plastics design and processing with a sound awareness of the environmental issues. Specific characteristics of the course are the project driven methodology and the integration of training periods in the industry as from the first year of the four-year long course.
Cartography in Flatland: An Overview of Analytical Techniques for Characterizing Nanocomposite Morphology
The performance advantages of certain commercial nanocomposites based on montmorillonite clays in thermoplastics are claimed to be great and the markets for these advantages large. Despite this commercial driving force, only a very small number of commercial nanocomposites are available because it has proven difficult to achieve the proper morphology for performance enhancement. Understanding, characterizing and manipulating nanocomposite morphology will play a crucial role in developing commercial thermoplastic nanocomposites. This technical presentation will outline the use of specific analytical techniques to characterize the morphology of polymer-clay based nanocomposites. It will begin by identifying the morphological information necessary in order to make better performing nanocomposites. The various techniques of x-ray diffraction, electron microscopy, optical microscopy, dynamic light scattering, atomic force microscopy, infrared spectroscopy, dielectric relaxation spectroscopy, and NMR will be described as they apply to nanocomposites.The talk will identify the deliverables of each technique, potential sources of analytical services for the technique, and special considerations associated with applying each technique to nanocomposites. The talk will conclude with a plea for the development of new techniques to provide information currently unavailable but necessary in the custom design of novel nanocomposites.
Cast-In-Place (CIP) for Joining and Repairing Live, PE, Gas Lines - II. Process Development
The term cast-in-place (CIP) describes a method for casting a non-leaking sleeve of polyethylene (PE) around the butted ends of PE pipes while the joint is leaking air at pressures up to 582 kPa. Mold development involved flow-through or vented molds with the latter providing better results with smaller injection charges. Sound sleeves were cast on pipe diameters ranging from 2.5- to 10-cm (1- to 4-in.) SDR. Aged pipe that had been buried for years was successfully joined to new yellow pipe material. Contaminants such as dissolved natural gas in the pipe wall or a solution of anti-static agents generate joints with inclusions or bubbles although strengths were good.
Cast-In-Place (CIP) for Joining and Repairing Live, PE, Gas Lines - III. Repair of Holes
The cast-in-place (CIP) approach was adapted to a simplified process for repair of holes in polyethylene (PE) pipes. The approach involves clamping an elastomerlined clamshell around the damage and, after the pressurized flow has been stopped, embedding the clamshell in a shell of PE. This work defines:Design aspects of a low-profile steel clamp including examination of several elastomeric gasket materialsDamage types that can be sealed including roughened and damaged surfacesInexpensive and portable methods for strapping the clamp securely around large holes to seal leaking gas under substantial pressureSuitable lengths for the clamp and the PE shell that is molded around it.The overall approach works quite well and clamp designs were found that will seal leaking gas at pressures up to 770 kPa. The clamp is capable of taking flattened pipe and rounding it as it seals holes that are up to 8-cm long in 6-cm diameter SDR-11 gas pipe. Clamp lengths should be no more than 1/3 the length of the cast PE sleeve.
Catastrophic Failure of the No-Slip Condition at the Wall during Torsional Flows and Development of Gross Surface Irregularities during Capillary Flow of Three Polymers
Wall slip behavior of three polymers was studied using flow visualization in cone-and-plate and parallel plate flows. The straight line marker technique and high speed cinematography were used to investigate the temperature-dependent wall slip behavior of a high density polyethylene, HDPE, a polydimethylsiloxane, PDMS, and an oxetane based thermoplastic elastomer, BAMO/AMMO. Capillary rheometry was also used to obtain data on the flow curves and to study the surface topology of extrudates. The straight line marker technique allowed the precise determination of the critical shear stress values for the onset of the catastrophic failure of the no-slip condition, which were determined to be 0.22 MPa for the HDPE and 0.073 MPa for PDMS, both of which were independent of temperature. In the vicinity of these critical shear stresses the extrudates of HDPE and PDMS exhibited surface distortions during capillary flow. The thermoplastic elastomer, BAMO-AMMO, on the other hand, did not exhibit any catastrophic failure of its no-slip condition and the surfaces of its extrudates remained smooth even at relatively high shear rates during capillary flow.
Cellulose Fiber Reinforced Polypropylene: Compounding and Properties Study
The physical properties and processing limitations of polypropylene copolymer compounded with hardwood and softwood cellulose fiber were investigated in this study. The use of maleic anhydride grafted polypropylene as a coupling agent between the cellulose fiber and the polypropylene copolymer was also explored. The addition of the maleic anhydride grafted polypropylene showed improvements to the tensile, flexural, izod impact, and heat deflection temperature properties of the cellulose fiber reinforced blends. The performance properties of the cellulose fiber reinforced materials are also compared to polypropylene blends utilizing more traditional thermoplastic reinforcements: glass fibers, talc, and wollastonite.
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