SPE Library

The actuator arms in some hard drives were found to distort after being subjected to an 80°C environmental test. This distortion was believed to be due to a relaxation of thermal residual stresses in the glass filled polyphenylene sulfide component of the arm due to the molding process. Changes were made in the molding process and this diminished the problem but did not eliminate it. Differential scanning calorimetry test on the plastic revealed that physical aging of the PPS was occurring during the 80°C environmental test and the changes in the molding process would have little impact on the motion which resulted in this process.

The gelling of soy protein-based PRF wood adhesives is studied. Soy protein isolate, in combination with phenol resorcinol formaldehyde (PRF) resins is useful in the finger joining of lumber. This unique technology has several advantages including an ability to bond green lumber, very rapid set at room temperature, excellent water resistance, and reduced formaldehyde emissions. The goal of this study is to quantify the effect of soy protein hydrolysis conditions and amine functionality on the gelling and ultimate modulus of soy-derived wood adhesives.

With the rising usage of plastic PET bottles and the rising need to recycle them, there is an increasing demand to refine the recycling process. It is very important to have the recycling process be cost and time efficient. The focus of this study is on the drying aspect of the recycling of PET. In this experiment, different parameters of the drying process were varied, specifically the time and the temperature. The strength was not significantly affected by time or temperature of drying. The melt index data showed that drying the PET at 177°C gave the best results. The overall best results seemed to be at 177°C, and a time around six hours. Longer or shorter drying times appear to degrade the material.

The selection of an automatic sortation system for separation of post-consumer bottles is of high importance for today’s recycler. The configuration of a modern recycling plant also needs to be carefully assessed, as different configurations in plant equipment have their own advantages and disadvantages and this can make the difference between a successful operation and a failure. This article examines the performance of spectroscopic sorting equipment in a recycling environment, which has to be viable at high speeds, problems associated with this technique as well as possible solutions to improve performance.

Environmental stress cracking (ESC) of acrylonitrile-butadiene- styrene (ABS) co-polymer caused by two kinds of non-ionic surfactants was studied by edge crack tension (ECT) tests. The dependence of the ESC on temperature and on the kind of surfactant was investigated. The fracture surfaces were investigated by a scanning electron microscope (SEM). It was found that the rise of temperature had a different effect on each surfactant. The crack propagation behavior of each surfactant at different temperatures was understood from the change of morphology at the crack tip.

One of the most common environmental exposures that nylon undergoes when used for automotive applications is that of salt splash, which commonly occurs during winter driving. This study looks at the effect of various salts (NaCl, KCl, CaCl2) on the mechanical and thermal properties of nylon when exposed to one and four molar aqueous salt solutions. Also, the partition of the salt/water solutions was studied, as well as the preferential absorption of one salt over another.

Besides other facets of product development, it is imperative for medical device manufacturers to take great efforts through proper evaluation and consideration of material properties under practical conditions to prevent product failure at the end-uses. The environmental stress crack (ESCR) induced by chemical agents plays a significant role on material performances. In this contribution, in-depth studies have been carried out on different medical plastic materials, such as polycarbonate, copolyesters, ABS, acrylics, rigid thermoplastic polyurethane and their blends. More attention will be focused on a copolyester material for its unique ESCR behavior. Variation of chemical agents (such as different types of hospital disinfection solutions) have great impacts on physical and functional properties. Various plastics shows distinct environmental stress cracking phenomena under different conditions. Mechanisms of ESCR phenomenon under different environments have been explored. Fibril reinforcement by cold crystallization and chain session by hydrolysis of the copolyester may have contributed to its excellent chemical resistance against a wide range of chemicals and its catastrophic failure in acidic or basic environment. In addition, appropriate definition of product failures is also critical in making materials decisions.

Polylactic acid, PLA, is a relatively new biodegradable polymer primarily used for biomedical as well as mass-market packaging applications. PLLA is a polyester comprising repeating units of the lactide residue with an asymmetric carbon atom. Because of its biodegradability to nontoxic products and good plastic properties of that polymer makes it suitable for use in film studies. De Santis and Kovacs showed that the unit cell of PLLA is pseudo-orthorhombic with dimensions of a=10.7 Å, b=6.45 Å, c= 27.8 Å and ?=?=?=90°, where the molecules assume a 10/3 helical conformation. (1).Eling et al reported the existence of another modification, which they called ?-crystal modification (2) Hoogsteen et al. studied the influence of the preparation conditions on the presence of the crystal modification (3). Fischer et al investigated solution grown crystals of lactide polymers (4). Also Kalb and Pennings estimated the crystallization of PLLA from bulk state and solution (5). Tadakazu and Masuko investigated the relationship between the fine structure of PLLA and its physical properties (6). The need for polymeric biodegradable films is well established. The use of films occurs in the packaging and disposable article industries. In light of depleting landfill space and adequate disposal sites, there is a need for biodegradable films. Currently films from nylon, polypropylene, polyethylene, polystyrene, PVC, are noncompostable, which is undesirable from an enviromental point of view (7). In this paper, we present our results on the development of structure in uniaxial and biaxial stretching of PLA and subsequent heat setting process as followed by the new spectral birefringence technique we adapted for rapid acquisition of birefringence during the course of heat setting.

This research seeks to determine the effect of chlorinated hot water on slow crack growth resistance in polyethylene using a test methodology that is quick and inexpensive. This will be done through the use of three point bend tests on specimens completely immersed in a bath of chlorinated hot water. The results will then be compared with results from the same test run without chlorinated hot water. Comparative data will be used to determine chlorine's effect.

Fish oil or conjugated fish oil was copolymerized with divinylbenzene and norbornadiene or dicyclopentadiene using BF3·OEt2 as an initiator in an effort to develop useful biodegradable polymers with rationally designed structures from natural renewable resources. Dynamic mechanical analysis, DSC, TGA and nuclear magnetic resonance spectroscopy have been used to characterize the resulting fish oil polymers. The results show that viable fish oil products ranging from rubbers to hard plastics may be synthesized by changing the type and amount of the comonomers used. The fish oil products are thermosetting polymers having highly crosslinked structures, glass transition temperatures ranging from 50 to 130°C, room temperature modulus of about 109 Pa, and excellent thermal stability, making the products useful for applications where current biodegradable plastics are not useable.

Recycling of polyethylene films [1] is carried out by their disintegration into regular flakes - the process is difficult because of dimensional (large surface, small thickness) and property (flexibility and rebound) characteristics of the films. The disintegration is typically carried out with the knife mills [2] which constitute the first units of the recycling line. Traditional mills operate on the principle of pressurized knife cutting [3] since it allows to carry on the disintegration at a narrow slit between cutting edges of the fixed (stationary) and the mobile (rotary) knives of the mill. Because of parallel arrangement of the edges and large surfaces of the films which call for high cutting forces the process induces strong vibrations [3, 4]. The latter are eliminated in the hyperboloidal - rotary cutting mill developed recently and evaluated in our lab [4].

In-line granulation, the size reducing of plastic trim as it comes off an extruder, tenter, frame, slitter or other production machine has many advantages over conventional trim handling methods. Small granulator size is an inherent requirement because of the limited installation space around these production machines and sound pressure levels must be low because of the proximity of the granulator to the machine operator. Precision Cutters, Inc. (PCI), has developed a unique line of small, very efficient, high productivity in-line granulators that meet all size and operating requirements for use in this advanced, closed, one-step trim to granulate process. The engineering principles of film granulation and throughput rates in kgs/kw-hr (lbs/hp-hr) are covered.

A complex carpet residue is obtained as a byproduct in the tertiary recycling of nylon-6 fibers from used carpets. It consists of mainly polypropylene, styrene-butadiene rubber and calcium carbonate, and is potentially a low cost, high volume waste stream with consistent properties. In this study, composites of carpet residue with polyethylene were evaluated for building and construction applications. As received carpet residue was first compounded with low density polyethylene, homogenized and devolatilized in a twin screw extruder. Later, blocks were prepared by the intrusion process and tested for their mechanical and thermal properties as well as the leaching characteristics of heavy metals and organic carbon. It was demonstrated that the prototypes of these blocks can be potential candidates for use in a novel thermal spacer application.

Inflatable structures are gaining wide support in planetary scientific missions as well as commercial applications. For such applications a new class of materials made of laminating thin homogenous films to lightweight fabrics are being considered as structural gas envelops. The emerging composite materials are a result of recent advances in the manufacturing of lightweight, high strength fibers, fabrics and scrims. The lamination of these load-carrying members with the proper gas barrier film results in a wide range of materials suitable for various loading and environmental conditions. Polyesterbased woven fabrics laminated to thin homogenous film of polyester (Mylar) are an example of this class. This fabric/film laminate is being considered for the development of a material suitable for building large gas envelopes for use in the NASA Ultra Long Duration Balloon Program (ULDB). Compared to commercial homogenous films, the material provides relatively high strength to weight ratio as well as better resistance to crack and tear propagation. The purpose of this paper is to introduce the mechanical behavior of this class of multi-layers composite and to highlight some of the concerns observed during the characterization of these laminate composites.

On-going research focuses on understanding the mechanochemistry during Solid-State Shear Pulverization (S3P) of recycled polypropylene (PP) and its blends. Free radicals formed during this process act as compatibilizing agents for ordinarily incompatible polyolefin blends. It was observed earlier with Nuclear Magnetic Resonance spectroscopy that each S3P cycle converts a small portion of polypropylene chains from isotactic to atactic stereoregularity. Small amounts of such atactic chain segments impart additional levels of toughness, which offset, in part, the damage associated with the inevitable chain scission. We determined how many processing cycles S3P-made recycled PP can endure without significant loss of mechanical properties.

Polymer latex modification of cement has increased the ductility of the resultant concrete. However, practical application of the concrete is limited since latex is used in a liquid form. In contrast, we have examined use of post industrial Recycled Acrylonitrile Butadiene Styrene powder (r-ABS). Pullout tests indicate an increase in adhesive bond strength between the polymer-modified mortar and steel re-bar. Thermogravimetric analysis is carried out to examine the influence of the latex on the kinetics of degradation. The results indicate a novel approach of using r-ABS in cement modification.

This paper describes electroless nickel and the scope for its many applications in mold making, maintenance and repair. While most mold builders are familiar with


 nickel solution for rust prevention in cooling water lines, many have remained unaware of the different formulations of electroless nickel plate and its capabilities as an engineering or functional coating applied by techniques firmly established in the electronics, fire-arms, automotive and other industries. Case histories of in-mold performance illustrate correct usage, proving that electroless nickel can offer properties equivalent to hard chrome plate, yet without the problems of thickness variation, anode deployment or the ever-rising environmental penalties and costs associated with chrome plating.

There are many advantages to air intake manifolds molded from Nylon 6,6 Glass reinforced composite material versus a pressure-cast aluminum manifold. Weight is significantly lowered and production costs generally are reduced. Performance improves with the precise control of the interior surface finish and reduced air induction temperatures. The Nylon 6,6 Glass reinforced composite material can be molded into intricate shapes by injection molding or lost-core process with reduced machining operations as well as Nylon 6,6 material is easily recycled. Production costs will continue to decrease as optimization of material, process and part integration increases. This study evaluates Nylon 6,6 Glass reinforced composite material in terms of the intake manifolds material key requirements such as thermal, heat aging, fatigue, impact, creep, stress and chemical resistance including multi fuels. This study would assist engineers in designing intake manifolds using Nylon 6,6 Glass reinforced composite material.

Solid Freeform Fabrication (SFF) of parts and components is an area of active development and tremendous potential. SFF is a layered manufacturing technique in which the required component/part is built from a CAD model. This model is mathematically sectioned into a number of layers and a material deposition or tool path is generated for each layer. A fabricator uses this tool path information to build the part, layer by layer. This family of manufacturing techniques offers several advantages over traditional routes, such as: no part specific tooling, fabrication of complex geometries to net shape, and greater design flexibility. There is also a significant potential for lowering cost of prototyping as well as small-scale manufacturing. Many of the SFF routes that are currently available are for fabrication of plastic, ceramic and metal parts. Some of these SFF techniques are, Stereolithography (SLA) Laminated Object Manufacturing (LOM) or Computer-Aided Manufacturing of Laminated Engineering Materials (CAM-LEM), 3D Printing (3DP)/Sander Prototyping (SP)/Droplet Deposition, and Selective Laser Sintering (SLS). Most of the SFF routes are similar in concept, i.e., model generation, followed by mathematical sectioning and layerwise building, and differ only in the method of layer fabrication. In order to manufacture ceramics and metals, the polymer based SFF methods have been adapted using powders as a second phase in a base polymer or fluid. Parts can then be made directly or indirectly. In the direct route, a green ceramic part is directly manufactured to shape. Alternately, in the indirect process, parts are made by infiltrating a ceramic or metal slurry into a polymer or metal mold made by SFF. Subsequent processing of these green parts (i.e., debinding/drying and sintering) is similar to that of traditionally manufactured components and results in a near net shape sintered part.

Clay-polymer nanocomposites have recently received significant attention from the industrial community because of their wide range of novel physical properties. The dispersion of clay particles in a polymer matrix can result in the formation of three general types of composite structure: (1) Conventional composites that contain clay layers unintercalated in a face-to-face aggregation with macroscopic segregation of the clay and the polymeric phases. (2) Intercalated clay composites that are formed by the insertion of one or more molecular layers of polymer into the clay host galleries. (3) Exfoliated clay composites where singular clay platelets are dispersed in a continuous polymer matrix. It is the presence of clay as described in (2) and (3) that is of interest in coatings for practical applications. Intercalation and exfoliation of clay can be conveniently monitored by measuring the (001) basal plane spacing of the clay platelets using X-ray diffraction (XRD). In this work, XRD revealed significant information about the morphology of the clay-polymer nanocomposites which, in turn, determined the physical performance of the coatings. Commercially available synthetic smectite clay, identified as a transparent, environmentally benign nanoparticulate material, has been studied in various polymeric matrices. Depending on the polymeric species, the basal plane spacing of the clay platelets ranged from 13.5 to 40 Angstroms. Details about the XRD results and the corresponding changes in the physical performance of the clay-polymer nanocomposite coatings will be presented.