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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NEW ADVANCES IN BONDING POLYOLEFIN-BASED PLASTICS
Since the first industrial production of polyethylene in the 1930’s, polyolefin based plastics have become inescapable in our daily lives and indispensable to the production of modern industrial products. Although polyolefin based plastics such as polyethylene (PE) or (HDPE), polypropylene (PP) and low density polyethylene (LDPE) have proven useful in innumerable applications they have also proven difficult to bond to with adhesives. Advances in the field of bonding to polyolefin plastics have been made by the introduction of various surface pre-treatment methods and adhesives based on polyolefins themselves. However, polyolefin based adhesives generally suffer from a lack of cohesive strength and surface pre- treatment adds significant cost and process complexity. Today we have new developments in the field of polyolefin bonding without the need for these cumbersome pre-treatment procedures. A novel two part acrylic adhesive developed by Henkel has shown to provide many desirable attributes for polyolefin bonding such as easy mixing, fast fixture time and superior bonding to untreated olefins.
HOW TO CONFIRM LIGHT CURE ADHESIVES ARE FULLY CURED
Light cure adhesives have become the assembly method of choice in high volume, automated manufacturing lines producing hand held electronics, medical devices, appliances, optical equipment, speakers, and screens/displays. Curing in seconds when exposed to light of the proper wave length and intensity, light cure adhesives offer infinite open times and allow manufacturers to reposition parts as necessary before cure begins. Available in formulations that respond to UV and/or visible light, these adhesives adhere to a wide range of plastics, as well as metals and glass. A primary concern for manufacturers using light cure adhesives is confirming that their light cure adhesive has fully cured. Incomplete cure can occur when cure lights degrade, have the incorrect wavelength or the incorrect intensity. In addition, the failure of the cure lights to illuminate the adhesive bond-line completely or for sufficient time can also result in incomplete cure, leading to device failure in the field. Until recently, no rapid, in-line method existed to provide a quantitative confirmation of the degree of cure. The Henkel Corporation recently developed a revolutionary new system designed to quantitatively confirm the complete cure of a light cure adhesive. Instantaneous, simple and In- line, the Loctite® AssureCure® System includes a unique adhesive, optical measurement equipment, and software that provides degree of cure measurements on 100% of your assembled devices.
STRUCTURAL BONDING ALTERNATIVES FOR PLASTICS
Plastics have become an integral part of everyday life. It would be difficult to identify a manufacturing process which does not use plastics in one from or another. Even products which appear to be composed exclusively of metals are usually coated, sealed, or adhesively joined using polymeric materials which improve the performance, appearance, and longevity of metal products. Plastics have achieved widespread acceptance due to the virtually limitless combinations of plastic types, fillers, and additives which can be compounded at relatively low costs and processed by a wide variety of methods. When designing assemblies made from or including plastics, it is often critical to structurally hold assemblies together with a reliable mechanism. Plastics can be reliably fastened to a wide variety of substrates using an engineered adhesive solution.
WHEN IS IT TIME TO DIGITALLY DECORATE? MAKING THE RIGHT CHOICES.
Industrial markets are ready to take advantage of direct to product decorating - printing to substrate. When is it time? Now is the time. The advantages are numerous: Inventory Reduction - on demand printing, Personalization - adding a new product level to current product line and added value to increase the bottom line, Green - very little waste and numerous recycling programs for consumable items. With advantages being clear, moving into the digial printing world requires a little preparation. Starting with how to select the appropriate printer from printhead selection to ink delivery system, ink selection, down to software. All key components in successfully moving into digitally printing. With a range of printing platforms from flatbed printers, high speed single pass systems to multipass systems - there is a solution for all decorating types. Taking the process step by step, being knowledable about the systems available and asking the right questions will put your company on the path to successful digital decoration in the production environment.
GAS PERMEABILITY OF POLY (4-METHYLPENTENE-1) IN A CONFINED NANOLAYERED FILM SYSTEM
Layer multiplying coextrusion was used to create nanolayered films of Poly (4-Methylpentene-1) (P4MP1) against syndiotactic Polystyrene (sPS). This paper investigates the crystal orientation of P4MP1 confined by sPS and examines the confinement effect on the multilayered film oxygen permeability. Demonstration of the confined P4MP1 layers can crystallize as in-plane lamellae bundles was characterized by microscopy and x-ray spectroscopy. A result of the in-plane bundle crystallization of 4MP1 was the formation of aligned open channels in P4MP1 crystals perpendicular to the film surface. This structure novel crystal structure reduces the tortuosity for gas transport through the film, which was verified by measurements of increased oxygen permeability tested by a Mocon Oxygen unit.
IMPROVING PACKAGE TRACEABILITY, MARKETABILITY, AND SUSTAINABILITY WITH DIGITAL DECORATING
The advent of piezo-based digital decorating enables marketers to deliver variable data, high impact graphics, and micro-targeted marketing with a single technology. Date coding, lot coding and traceability- back to the product’s origin- are now possible, enabling companies to satisfy increasingly stringent FDA requirements. And with no changeovers needed, marketers can economically create regional or store-level campaigns, delivering unique messages to minute market segments. Those messages are certain to pack a punch with near photographic quality images. Better yet, direct-to- package printing improves sustainability by eliminating labels, films and other consumable materials.
PHYSICAL VAPOR DEPOSITION AND UV CURABLE COATINGS
Environmental concerns with traditional chrome plating continue to expand. Parts finishers worldwide are searching for alternative that provides the visual appearance and durability of chrome plate, but without the environmental side effects and costs associated with this decades old process. “Chrome look” processes and coatings for decorative and automotive lighting PVD applications have been used in the UV curable coating industry for over twenty years. As development of UV curable coatings for PVD has progressed, so has the understanding of the PVD process and its unique capabilities and applications. This paper will address the current chrome plating process, advantages of PVD as chrome alternative, challenges associated with the various steps and layers of PVD applications, and suggestions for successful implementation of UV/PVD systems.
WIRELESS DEVICES DECORATED USING NON-CONDUCTIVE VACUUM METALLIZATION (NCVM) TECHNIQUES: CONSIDERATIONS AND COMMON FAILURE MODES
The Non-Conductive Vacuum Metallization (NCVM) process has become a mainstream metallization technology to achieve metallic like appearances on the surfaces of plastics used in wireless electronic devices while maintaining radio frequency (RF) functionality of the internal antennas. The impact on device performance and reliability of NCVM coatings has been discussed based on the most common failure modes and industrial testing standards. This paper discusses the effects of environmental conditions as well as construction variation of NCVM systems as they relate to various customer- impacting failure modes such as discoloration/corrosion, delamination and RF interference.
EMERGING FIBER LASER TECHNOLOGY FOR MARKING PLASTICS
Ytterbium Fiber Lasers are transforming laser marking of plastics. For the proper application, superior results can be achieved versus Nd:YAG and Vanadate marking lasers. However, fiber lasers are not direct replacements without thorough evaluation, and not all lasers are created equal. The metric for beam quality is M2. The smaller the M2 value, the better the beam quality, whereas M2 = 1 is the ideal laser beam. A laser with superior beam quality can be focused to a small spot size, which leads to a high energy density which is, for many applications, desirable or even required. Such is the case for many thermoplastics including POM Acetals such as Delrin. Fiber lasers are considerably less expensive to procure with zero consumables, only electricity. Further, these lasers are a “Greener” technology than YAG or Vanadate.
PREPARATION OF INTERCALATED ORGANIC/INORGANIC HYBRIDS VIA IN SITU SYNTHESIS
Nanostructured organic-inorganic hybrid materials, including polymer nanocomposites, layer-by-layer assembled thin films, have been extensively investigated over the past two decades and have found wide applications owing to their excellent performance. Either regular polymer nanocomposites or layer-by-layer assembled thin films are typically prepared using pre-synthesized nanofillers/nanoplatelets. Here, we report a new approach to prepare nanostructured hybrid materials via in situ synthesis of nanoplatelets within the polymer/monomer matrix. Alpha-zirconium phosphate (ZrP) was synthesized in a solution system containing a polymer (such as polyethylene glycol, PEG) or monomer. During the synthesis of ZrP, PEG chains were embedded into the ZrP interlayer space, leading to a larger interlayer distance, which is similar to the intercalated layered compound. Proper formulation ratio proved to be critical to avoid forming pristine ZrP, and avoid interfering the growth of the layered structure of ZrP. It has also been found that longer polymer chains are desirable for minimizing the formation of pristine ZrP, but would not affect the interlayer distance. All the PEG chains are perfectly parallel to the layer planes. Besides polymers, many other molecules have also been successfully embedded into the interlayer space to form an intercalated structure during in situ synthesis.
EXPERIMENTAL STUDY ON RUBBER-ASSISTED EMBOSSING OF MICRO FLUIDIC CHIPS
A flexible micro fluidic chip is difficult to fabricate using the standard hot embossing technology. In this study, rubber-assisted embossing of a micro fluidic chip was investigated. A thin polymer film was thermoformed into microchannels by rubber as soft counter-tool. Different processing conditions, as well as material selections, affecting the thickness uniformity and replicated depth were examined. A flexible micro fluidic chip was fabricated via sealing the microchannel with a layer of transparent adhesive film. A droplet of colored water flowing into the microchannel fast and steadily was observed. Experimental results indicated that the microchip had a uniform channel and good leak tightness. The proposed method demonstrated the ability of fabricating a flexible 3-D microchannel.
DIRECT FABRICATION ON THE POLYMER SURFACES BY USING PRECISION TOOLING MACHINE AND CHARACTERIZATION OF HYDROPHOBICITY AT VARIOUS ROUGH SURFACES
This report described the hydrophobicity of polymer surfaces, PMMA and polycarbonate. Micro-sized pillar type structures were prepared by the precision machine which could precisely fabricate the various rough surfaces on the polymer surfaces. We considered the geometric parameters, x/d and z/x, to find the factors affect of wettability. The volume of water droplet intruded in pillar spacing affected to increase the hysteresis. Furthermore, the air-pocket formed in solid-vapor contact line was attributed to reduce the hysteresis. We also demonstrated the effect of the surface defect through the ductile polymer, polycarbonate. The polycarbonate surfaces showed higher sliding angle than PMMA, which caused the surface defect pinning with water droplet.
PRECISE INJECTION MOLDING OF BIO-ABSORBABLE HAP/PLA COMPOSITES
Hydroxyapatite (HAp)/ polylactic acid (PLA) composites with different particle size distribution were fabricated using microinjection and hot compression molding. Physical properties such as mechanical and heat properties of the composites were also investigated, as were improvement mechanisms attributable to mixing particle size distribution. Flexural strength of neat PLA molded parts at room temperature was about 80 MPa, whereas that of HAp/PLA parts was 48–49 MPa, suggesting that flexural strength decreased because of dispersed HAp particles. The reduction of flexural strength apparently depended on the HAp particle size. The flexural modulus of neat PLA parts was about 3.0 GPa at room temperature, whereas that of HAp/PLA parts was 4.0–4.8 GPa, suggesting that the flexural modulus was higher because of the dispersed HAp particles. The flexural modulus of composites with bimodal particle size distribution was greater than that of composites with a monomodal particle size distribution. The height of microneedles of composites with a bimodal particle size distribution was slightly greater because of the lubricant effect of HAp.
STUDY OF THE INJECTION MOLDING TECHNOLOGY FOR THE NON-CIRCULAR LENS
Compared to symmetrical and circular lenses, non-circular lenses have more issues on controlling process parameters during injection molding process. Unbalanced filling pattern and thickness variance in lens typically result in more defects which become a critical challenge in product developments. A study of non-circular lens with an aspherical contour through computer simulation assistance and design of experiments was presented. A non-circular lens and two convex lenses were assembled into a barrel to form an optical modulus for a mini projector. The optical characteristic of mini projector was dominated directly by the accuracy of the optical modulus. In this study, a reasonable injection speed which could reduce melt viscosity in molding process was calculated by simulation software and then design of experiments was conducted to investigate the influences of the molding conditions on the part quality experimentally. This study provides a systematical way to predict in which area a defect occurs and determine the optimal molding parameters based on simulation results and statistical experiments.
DYNAMIC BEHAVIOR AND EXPERIMENTAL VALIDATION OF CELL NUCLEATION AND GROWING MECHANISM IN MICROCELLULAR INJECTION MOLDING PROCESS
We present the recent development of three-dimensional prediction of dynamic behavior of cell nucleation and growing mechanism, and the effect of nucleation-growing competition in microcellular injection molding process. Simulations of microcellular foaming process of injection molding are carried out for polyolefins with supercritical fluids (SCFs) carbon dioxide and nitrogen. In addition, we validate simulation results with experimental results to prove the capability of 3D prediction of microcellular foaming process and further compare simulations of microcellular injection molding and conventional molding to provide insights and economic guidance into design and manufacturing of injection molding products.
TEMPERATURE INVESTIGATION IN REAL HOT RUNNER SYSTEM USING A TRUE 3D NUMERICAL METHOD
Hot runner technology has been the solutions to the molding problems on many plastic injection products, such as automobile bumper, LCD/TV cover, bottle cap and so on. However, the mechanism behind the hot runner system is too complicated to be fully understood. In addition, there exist some critical issues in the current hot runner technology, such as temperture control issues, flow imbalance, and material degradation. As a result, the simulation technolgy is highly needed for hot runner designers and makers to examine their designs before the real manufacturing. Through simulation analyses, designers and manufafctuers are able to catch the potential issues on their hot runner systems and revise their designs. Hot runner simulation technology helps with the investigations into the behavior in hot runner system. In this paper, a true 3D numerical method is proposed and applied to investigate the temperature behavior in a real hot runner system for PC material. The experiment is conducted and the simulating result is compared with that from the experiment for the validation purpose.
THE SKIN/CORE MATERIAL DISTRIBUTION OF A CO-INJECTION MOLDING PROCESS: THE EFFECT OF PROCESSING CONDITIONS AND MATERIAL SELECTION
With the growing use of co-injection molding process, an understanding of skin/core material distribution in the cavity is essential. We presented numerical simulations concerning factors including filling ratio, material viscosity, and injection rate. Both core penetration behaviors and skin ratio uniformity from the material distribution profiles were compared. In addition to material distribution predictions, numerical simulation also revealed breakthrough points and cornering-effect locations. This is helpful for the part manufacturer to enhance the benefits of the co- injection process through the computer-aided simulation.
ANALYSIS OF THE PROPERTIES AS CONTENT OF END-GROUP FOR POLYCARBONATE (PC) IN MELT POLYMERIZATION PROCESS
There are two processes to polymerize polycarbonate in the petrochemical industry: One is interfacial polymerization(interfacial PC) and the other is melt polymerization(melt PC). Recently, the latter is mostly used in that it is eco-friendly process. The most difference of product produced by two systems is the content of specific end-group. It is detected to a little bit value in interfacial polymerization, while it generally has more content in melt polymerization. It is supposed that the more content of the end-group is, the bigger change of the property induce as surrounding environment. In order to analyze an effect of the end-group, polycarbonate substituted to other end-group was made from melt PC using a suitable end-capping agent. And then, several properties were examined like melt index, viscosity and color. As the result, the end-capped PC showed less change of the properties than general melt PC, and it is similar to interfacial PC. It was verified that the properties of melt PC is adversely affected by the specific end-group.
MARKET SITUATION AND POSSIBILITIES FOR INFORMATION PROCUREMENT OF BIOPOLYMERS (BIOPOLYMER DATABASE)
In the last three years the production capacities of biopolymers increased threefold. The current trend in the development of biopolymers is towards bio-based and durable materials, it veers away from biodegradable and compostable materials. As a result of this change and the significant growing market there is a bottleneck regarding the availability of information and technical data of biopolymers. The biopolymer database offers a knowledge platform about biopolymers with producer data and newly measured comparable properties. The presented comprehensive database reflects the market situation and serves as connection between manufacturers, converters and end users.
IS RTC THE LONG AWAITED PANACEA FOR INJECTION MOLDED PARTS?
In contrast to conventional injection molding, where the tool is cooled continuously, in Rapid Temperature Cycle Molding RTC™ the cavity surface is rapidly heated to around the glass transition or melting temperature of the plastic before melt injection. Benefits are summarized and quantitative results cited. These include: achieving fine surface finish and gloss, including for foamed and filled materials (Ra for foamed ABS reduces from 1500 to 30 nm and for LGF PP from 1600 to 150nm); elimination of visible weld line defects; improved transcription of surface micro- features; improved optical properties in clear moldings; reduction of injection pressure, allowing longer flow paths, lower machine tonnage, part thickness reduction with reduced cooling time, and reduced molded-in stress. Implementation of the two leading technologies for implementation of RTC™ are described: heating with steam; or use of external induction heating to rapidly raise the cavity surface temperature, both followed by water cooling. A case study for RTC™ is described, leading to series production of a metalized part for a German automotive OEM. Performance requirements dictated a thin metalized layer (0.2 -0.3?m), formed by physical vapor deposition. This being insufficient to hide weld line defects, and use of a thick primer layer (15 ?m) being unacceptable, raising the cavity surface by RTC™ induction heating was trialed and shown to be entirely successful in removing defects.
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