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.
There are many challenges to on-line thickness measurement for blown films, some of which are:Getting data fast enough to make timely thickness profile corrections. This can be a problem with down stream stationary gauges.Measuring soft, tacky films or high optic films with gauges that ride in contact with the filmMeasuring films containing polyamide (nylon) with an “on-the-bubble” capacitance gauge. The capacitance of nylon changes rapidly in the temperature range of the cooling bubble just above the frost line (60 – 100°C / 140 – 210°F) causing inaccurate thickness readings. This precludes the use of capacitance gauges until the film is cooled below 40°C (100°F). (Fig. 1)To address these issues, a relatively new on-line technology utilizes a non-contact scanning gauge mounted downstream of the primary hauloff to measure the layflat web (double sheet). A novel software algorithm separates the double sheet measurements into full circumference profile scans. The data can then be used to take corrective action on average thickness or thickness profile variation. European patent EP 1 207 368 A2 provides a description of one of several possible methods used to implement this technology.1By measuring the layflat with a scanning gauge head, data collection rate becomes nearly independent of the process oscillation time. This addresses the first challenge. NOTE: the oscillating die or hauloff must be moving for the technology to work. Also, the oscillator must traverse far enough to generate sufficient variation in the data to perform the separation function (this distance varies according to each supplier’s experience).Using a non-contact transmission gauge (e.g. nuclear, X-Ray, IR, or capacitance) handles the second challenge -- problems associated with contacting the film.Measuring nylon films downstream of the hauloff, where the web is cooler, allows the use of a capacitance gauge in addition to nuclear, X-Ray or IR gauges. This addresses the third issue.
Four different polypropylene resins were extruded using the tubular and the cast film processes. The morphology of the films was observed by SEM and the effect of extrusion processing variables on the morphology was investigated. Melt rheological experiments were carried out to characterize the behavior of the polymers. It was found that the molecular weight distribution and the chain structure as well as the processing conditions had important effects on the morphology. Efforts focused on obtaining a lamellar crystalline morphology by controlling the processing conditions. The possibility of generating a porous membrane from the initial morphology using a stretching technique was evaluated. The initial lamellae arrangement of the precursor film is shown to play a significant role in obtaining a porous structure.
The Gear noise was studied in an individual gear mesh for a two shot molded gear. The two layers comprised of a hard core and softer tooth of the gear. PBT, PA 66 and POM were used as the hard core and TPE for the softer skin. This experiment was limited only to the noise of the gear mesh using a sound meter and not the wear of the gear teeth. The “softer” teeth demonstrated smoother and quieter gear meshes with straight PA 66 and POM parts. It was found that the noise levels reduced as much as 25% when one of the driver/driven gear had softer teeth. The sound of the driving motor was isolated from the test gears using the acoustical fiberglass shield.
Electrical conductivity needed to dissipate electrostatic charge (ESC) build-up that occurs on polymeric surfaces in the space environment can be achieved through the use of single-walled carbon nanotubes (SWNTs). This study presents two samples of SWNTs prepared by two different processes and their effect upon macroscopic polyimide properties. The neat SWNTs were characterized by ultraviolet/visible (UV/Vis) and fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), and thermogravimetric analysis (TGA) prior to addition to the polymer through a surface coating process and bulk inclusion. The nanocomposites were evaluated for nanotube dispersion, electrical conductivity, mechanical, and optical properties.
The trend toward increased usage of renewable resources has led to the growing popularity of wood-filled materials. These emerging materials require extensive testing – beginning with formulation and ending with the final manufactured product. In the early stages of development, it is possible to acquire data comparing differences between recipes utilizing a Mixer/Measuring Head. The given blend can be compounded with a customized twin screw extruder and torque rheometer. Finally, a single screw extruder can quantify the rheology of the compound using a capillary die. The objective of this work is to investigate the behavior of a polyolefin based wood-filled compound using a torque rheometer.
The pilot “REACH-RS” program was implemented in the summer of 2004. The PSU “REACH-RS” program is the culmination and result of the interactions between the director of the PSU/NSFREU/ RET program and high school science teachers, counselors and administrators. This interaction identified the need for an academically-oriented summer program for talented high school juniors and seniors. Selected high school students are invited to participate in a series of seven-day, hands on-oriented workshop with in-lab activities in such subject areas as “SMET of Materials Identification,” “Computerized Materials Selection Techniques,” “Toy Manufacturing Via Rotational Molding,” “Foam Production Technology,” “Ultra-sonic Bonding Techniques,” “Injection Molded Electrically Conductive Plastics In EMI Applications,” etc. Each experiment is designed to inculcate and reinforce in the student the practical applications of scientific, mathematical, engineering and technological concepts. Program sponsorship was accomplished via funding provided by 3M Foundation. Program outcome include but not limited to: preview and introduction to college life, improvement of communication and inter-personal skills, acquisition of technical proficiency in the areas of materials, nanomaterials and processing for the participants, and the development of academia-industry partnerships.
Natural crystalline graphite based graphite intercalated compounds [GICs] were exfoliated into sub-micron graphite flakes. Graphite nanocomposites were fabricated by combining the exfoliated graphite flakes with nylon66 resin. The mechanical properties of these composites showed considerably higher modulus than those of composites made with commercially available carbon reinforcing materials (i.e. CF VGCF and Carbon Black). Also the electrical property was improved by adopting appropriate fabrication conditions.
A joint effort between Delphi Corporation Hendrickson International and Oak Ridge National Laboratory has led to the development of carbon fiber reinforced polymeric tie rod for use in heavy-duty truck suspension systems. The composite tie rod tube assembly is 65% lighter than current metal tubes with equivalent or improved performance. This paper will summarize the design and test methodology which have led to successful implementation of this product for heavy truck applications.
SmartTrac impedance sensing technology provides an important new method for thermoset molders to improve cure process productivity and quality. Similar to dielectric cure monitoring impedance technology uses the changing electrical properties of the thermoset as it cures to determine the optimum time to end the cure. This paper reviews the implementation of impedance sensing technology in SMC and phenolic and presents results from several production and lab applications.
PowerPoint Presentation at ACCE 2004.
General Motors’ next generation full-size truck frames are currently 80 pounds over their targeted weight. By replacing the current steel transmission cross-member on General Motors’ full-size trucks through the application of a composite material transmission cross-member a substantial weight reduction will be achieved. Reducing the weight of General Motors’ full-size trucks will consequently increase the fleet-wide fuel economy for the company’s truck line allowing CAFE requirements to be met more easily.
PowerPoint Presentation at ACCE 2004.
Long fiber-reinforced thermoplastics have excellent mechanical properties and stiffness / weight ratio which is of particular interest to the automotive industry. The new in-line compounding processes for long-fiber materials offers users more flexibility as they are able to both compound and process such materials in accordance with their own formulation and also use ready-made compounds.
Recent developments in the area of UV cured fiberglass resins and gel coats may provide significant advantages to composite parts manufacturers. These advantages lie in the area of greater speed better efficiency and the significant reduction in styrene. Interest in this later advantage has spurred commercialization of UV cured composites where regulatory pressure has required a different approach that traditional peroxide cure mechanisms.
Most people are aware of what natural fibers are but few know of the diverse capability of this natural resource and unfortunately industry pressures over the past several years to reduce costs focused on trying to refine well established technologies using glass or wood fibers or to a certain extent injected molded polymers. It has only been through recent pressure by some of the larger OEM’s that natural fibers have been gaining broader interest for both their performance and environmental benefits as compared to older more comfortable based technologies. Cost versus performance is a delicate balancing act. Fortunately natural fibers go a long way on striking a balance between both of these most common demands. When considering performance natural fibers offer an unlimited range of lighter weight possibilities for interior and exterior applications. Most common today natural fibers are commingled into a nonwoven mat with fiberized thermo plastic polymers such as polypropylene and polyester for use in common interior applications that include door panels center consoles pillars and inserts. However advancements in the range of available natural fibers and specialty polymers along with a continuous improvement of the nonwoven process are now providing for greater heat stability to meet the elevated requirements for over head systems package trays and topper pads. Increased demands for occupant safety give further reason to consider natural fibers as few other materials provide the same impact characteristics with the base material. For exterior applications natural fiber mats used as the base material in sheet molding compounds will find their way into bumper reinforcements wheel well liners and under hood applications. The industry historically focused on direct material cost. In this simplified approach natural fibers seldom will come out to be the low cost alternative but when considering the benefits derived from one-step processing the end cost of the finis
Recent advances in thermoplastic resin chemistry have enabled the development of a thermoplastic polyester foam core material with excellent thermoformability elevated temperature and chemical resistance and superior fatigue endurance. Possessing high strength and rigidity this foam product fulfills the demanding requirements for structural core materials used in sandwich composites though it can be successfully used without facings for many applications. Presented will be the physical properties including at elevated temperatures in comparison with rigid polyurethane foams and other core materials. The results of an extensive sandwich flexural fatigue study will also be reviewed and discussed. Finally examples of complex thermoformed shapes will be shown both of the foam alone and in combination with GMT facings to form contoured structural sandwiches all at once.
Sustainable nanocomposites have been successfully fabricated from renewable cellulose acetate (CA) environmentally benign triethyl citrate (TEC) plasticizer and organically modified clay. The effects of processing conditions such as mixing methods pre-plasticizing times retention times (RT) and addition of compatibilizer maleic anhydride grafted cellulose acetate butyrate (CAB-g-MA) on the performance of these nanocomposites have been evaluated. The cellulosic plastic with CA/TEC (80/20 or 75/25 wt. %) was used as the polymer matrix for nanocomposite fabrication. The morphologies of these nanocomposites were evaluated through X-ray diffraction (XRD) Atomic force microscope (AFM) and transmission electron microscopy (TEM) studies. From all the sequential mixing methods used powder-powder mixing leads to the most transparent nanocomposites. Cellulosic plastic-based nanocomposites obtained using increased pre-plasticizing times and RT showed better-exfoliated structures. Cellulosic plastic-based nanocomposites with 5 wt.% compatibilizer contents showed better-exfoliated structure than the counterpart having 0 or 7.5 wt.% compatibilizer contents. Polygonal shape of exfoliated clay platelets was observed with 500 nm width and 800 nm length by AFM and TEM imaging. The mechanical properties of the nanocomposites have been correlated with the XRD and TEM observations.
Bayer MaterialScience has focused on developing new composite technologies combining a lightweight low-density core together with fiber-reinforced polyurethane skins. A Bayer MaterialScience polyurethane chemistry designated Baypreg®F is ideally suited for constructing composites that require a high stiffness to weight ratio. The components of a composite made using these chemicals can be easily manipulated to allow part producers extensive freedom in manufacturing a wide variety of part designs and configurations. This paper presents the development of a mathematical model for the prediction of composite properties. It specifically focuses on composites constructed with paper honeycomb as the core material and with glass fiber mat as the facing material. For typical composite applications load-deflection behavior is the most significant indicator of performance. Subsequently data accumulated from the testing of the core and facing materials individually is used to predict the load-deflection behavior of a composite constructed utilizing the polyurethane chemistry. The theoretical predictions are compared directly to test data obtained from composites with specific constructions. A discussion of the model’s predictive ability focusing on part design to meet customer requirements quickly and efficiently will be presented. Work targeted towards refining the model will serve as a conclusion to the discussion.
New automotive applications of sandwich composites require the development and characterization of reliable attachment techniques needed for the creation of functional structures. Baypreg®F is Bayer’s proprietary name for the two-component polyurethane material that bonds and holds the composite structure together which is normally made of a honeycomb-type paper core sandwiched between glass fiber mats. In this paper we present testing results to compare different attachment strategies applicable to this type of sandwich composites. As joints are a potential source of stress concentration and weight increase their performance should be as good as if not better than the underlying composite. We compare the performance of adhesive bonds embedded inserts and mechanical fasteners and discuss their advantages and disadvantages. Furthermore we discuss characterization of attachment techniques for computer simulations and outline plans for further development and testing.
In May 2003 Oak Ridge National Laboratory (ORNL) and Pacific Northwest National Laboratory (PNNL) began collaboration on a four year research effort focused on developing technically robust and economically attractive joining techniques to overcome the technical issues associated with joining lightweight materials in heavy vehicles. This work is being performed concurrently with an industry program led by Delphi to develop and commercialize composite chassis components which is a “focal project” that will utilize the improved joining methods. The initial joint design for a composite component to steel member will likely include mechanical fasteners requiring holes in the composite member. Several hole fabrication methods have been evaluated including drilling with tapered and Forstner bits laser cutting water jet cutting and punching. Several methods have been used to determine the damage associated with hole fabrication. One non-destructive method flash thermography has good correlation with x-ray dye penetrant results and in some cases shows finer detail and can indicate the location of damage through the thickness of the composite. A testing methodology has been developed to study the effects of bolt torque level on a pultruded fiberglass composite material. Informati on derived from this will ultimately support the characterization of bolted composite assemblies and provide insight for the design and manufacture of the composite chassis components. Loss of pre-load data can be used to predict the creep response in the through-the-thickness direction of the composite materials.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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