SPE Library
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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Conference Proceedings
A Study on the Relationship between the Size of the Company and It?s Sustainability Spending in the Plastics Industry
Business corporations? emphasis on sustainability is ever increasing which is evident by the increase in sustainability spending. Each year, companies are spending more on sustainability. This research is an attempt to understand if the sustainability spending depends upon the size of the company as measured by its revenue. Moreover, the paper focuses on the relationship between sustainability spending and size of the company in plastic industry. The study is the second survey of its kind and is based on the global inquiry with the members of the Society of Plastics Engineers (SPE). Based on the results of Chi-square test for independence, we found that there is no relationship between sustainability spending and the size of the company.
Effect of Brightness, Color and Transparency on Scratch and Mar Visibility in Polymers
Scratch and mar damages can critically impact the aesthetics of polymeric surfaces. Improving scratch and mar visibility resistance of polymers is of big interest for academic and especially industrial arenas. In this paper, we investigate the influence of surface brightness, color and transparency on scratch and mar visibility resistance in polymers. A new psychophysical test based on Multidimensional Scaling (MDS) statistical method was utilized to determine mar visibility resistance onset. It has been found that scratch visibility resistance decreases with greener, lower brightness and higher transparency samples. Preliminary results show that MDS is a powerful tool to disseminate the psychophysical evaluation of mar damage. This research paves the way for a standardized methodology to reliably quantify scratch and mar visibility resistance in polymers.
CAE Verification on Gas-Counter Pressure Mechanism in Gas-Assisted Injection Molding
The tradition packing way is that the injection unit holds the high pressure in a few seconds, which is highly energy-consuming. Gas Assisted Injection Molding (GAIM) refers to injecting gas into the short shot melt in the packing stage, the compressed gas is used as the medium to push melt and maintain pressure, which can save the material and energy. Therefore, the hollow area and penetration length are mostly required in end product quality. This study visualizes molding flow, and uses gas counter pressure mechanism in the gas assisted molding process, the melt flow behavior is influenced by controlling the counter pressure, so as to discuss the effect of counter pressure mechanism on the hollow area and the penetration of gas assisted molded articles. This study designs in-mold visible mold, and uses clip-shape cavity for experiment on gas assisted injection molding with counter pressure mechanism. The flow field of two phase fluid and fountain effect in different counter pressure conditions are observed by high-speed photography and adding particles, the relationships among the penetration length of finished product, hollowed evenness and molding parameters are analyzed by mold flow analysis software, and the database of gas assisted injection molding under counter pressure mechanism is created. The experimental results show that the gas counter pressure is applied to gas assisted molding, the hollow area is reduced and the penetration length of finished product can be increased, so as to uniform the hollow quality. And the result of mold flow analysis software will verify the experiment.
Non-Destructive Monitoring of Damage in CFRP using Ultrasonic Birefringence
A non-destructive testing method ? ultrasonic birefringence ? employing ultrasonic transverse waves and their polarization dependent velocity and attenuation is proposed to monitor fatigue damage in laminated CFRP and damage induced by tensile loading of braided CFRP. A calculation approach is presented to predict the measurement results in laminated CFRP. The method exploits the inherent elastic anisotropy of fiber reinforced plastics to characterize damage. The increase in attenuation and decrease in velocity which is induced by the transverse matrix cracks in fatigued laminated CFRP is matched with simulated results to estimate the shear moduli of each fiber direction in the laminated CFRP and hence characterize the fatigue state in each fiber direction. In the braided CFRP case the method is used in a preliminary attempt to demonstrate the anisotropy of damage induced during tensile testing.
Comprehensive Sterilization Study of Multiple Polystyrene Grades and Other Polymers
There are no ?all encompassing? sterilization studies which combine all available sterilization methods at varying intensities comparing polystyrene to other polymers commonly used in medical packaging and devices. This paper will show physical property data over a two year time span using multiple general purpose polystyrene (GPPS) and high impact polystyrene (HIPS) grades, comparing them to seven other polymers, including high density polyethylene (HDPE), polypropylene (PP), polyethylene terephthalate (PET), copolyester (PETG), acrylonitrile butadiene styrene (ABS), impact acrylic (PMMA), and styrene butadiene copolymer (SBC). The sterilization methods used include two intensities each of Gamma, E-Beam, and Ethylene Oxide (EO or EtO).
Color Transfer from Point a to Point B: A Review and Examination of, Crocking, Rub-Off, Bleeding, Blooming, Blushing, Transfer, Migration, Extraction, Sublimation, Exudation, Plate Out, Diffusion and
Virtually any industry that makes use of colored thermoplastic compounds whether made from master batch or compound has the potential to be negatively impacted by the movement of color from the manufactured item to the surrounding environment, eg; hands, clothing, or other objects. Industries where this may be of critical importance include but are not limited to fiber (clothing, upholstery and carpet), food packaging, toys, automotive, and household appliances. No one appreciates the color of their new clothing transferring to their couch, or the color of a child?s new favorite toy transferring to their face because they fell asleep laying on it. This paper attempts to review the above phenomenon, many of which have similar definitions, but may indeed have different mechanisms. In some of the above instances mechanisms for their occurrence are proposed and methods hypothesized as to how to predict and therefore how to mitigate their presence.
The Effect of Matrix Viscosity and Compounding Parameters on the Morphology and Electrical Conductivity of PP-CNTs/PS Blends
Co-continuous polypropylene (PP)/polystyrene (PS)=53/47 vol% blends containing 0.7 vol% multi-walled carbon nanotubes (CNTs) were obtained by melt-mixing in a conical twin-screw micro-compounder. To study the influence of melt viscosity ratio, PS with different viscosities were selected. With decreasing viscosity ratio, the better uniform co-continuous structure and higher electrical conductivity could be obtained. The compounding parameters, including the mixing time and the sequence of incorporation have been investigated. The results indicated that high melt viscosity ratio could not hinder the migration of CNTs from PP into PS phase. Higher rotation speed, mixing simultaneously and shorter mixing time lead to the better uniform co-continuous morphology and higher electrical conductivity
Foaming Behavior and Control of Polypropylene/Nitrogen System in Microcellular Foam Injection Molding
Foaming behavior of polypropylene/nitrogen system in microcellular foam injection molding was investigated by using a 50-ton injection molding machine equipped with Mucell? gas injection unit. The evolution process of cell morphology was obtained by regulating the filling ratio. Both the filling ratio and the injection velocity have significant effects on cell morphology. To maximize the cell density, lower injection velocity should be used and the filling ratio should be controlled in the reasonable level of about 80%. With an extremely large filling ratio, cells formed in filling stage can be dissolved back into polymer melt and the special cell morphology with longitudinal cells can be obtained.
Solid-State Thermoplastic Nanofoams via a Novel Low-Temperature Saturation Pathway
A low-temperature saturation pathway to create thermoplastic nanofoams is presented. We conducted saturation by CO2 to a temperature as low as -30 øC and successfully fabricated PC nanofoams (cell size 20-30 nm, void fraction up to 60%), PMMA nanofoams (cell size 30-40 nm, void fraction up to 86%), and PSU nanofoams (cell size 20-30 nm, void fraction up to 48%). Cell nucleation densities exceeding 1015 cells/cm3 were achieved.
Lowering the saturation temperature results in a significant increase in solubility, which is essential for creating nanofoams. Cell nucleation density increases with CO2 concentration and average cell size decreases with CO2 concentration. All three polymers exhibit very similar behaviors. At sufficiently high CO2 concentrations, cell nucleation densities reach the range of 1012 - 1015 cells/cm3, and corresponding cell sizes fall below 1 æm into the nanometer range. The CO2 concentration for generating nanofoams is above 18.9%, 32.6%, and 12.3% for PC, PMMA, and PSU, respectively. Representative processing conditions for creating nanofoams with cells below 100 nm are presented. The method of lowering saturation temperature can be applied to create nanofoams in other polymers, polymer blends, copolymers, and polymer nanocomposites.
Effects of Processing Parameters on Experimental Fiber Orientation of Glass Fiber-Reinforced Injection Molded Composites
Effects of injection speed on the experimental orientation of long, semi-flexible glass fiber-reinforced polypropylene composites using an end-gated plaque geometry exhibiting a complex 3-dimentional flow field were quantified. Three injection speeds were considered with constant mold and screw temperatures. Samples were subsequently used to obtain experimental orientation and fiber length distribution data. Orientation data was obtained using a slightly modified version of the Method of Ellipses, which is used for rigid fibers. Injection speeds of 1, 2, and 4 seconds were used with a mold temperature of 79oC. Orientation data along the center plane and also images along the composite width were obtained and compared. Preliminary data suggests that the orientation at these injection speeds does not change considerably along the center plane from one mold fill time to another. More data is needed to conclude whether orientation is changing significantly along the width of the part.
A New Evaluation Method of O-Ring Rubber Seals by Compressive Load Test
O-ring Rubber seals are widely used for hot water pipes and various parts of residential gas appliances for water heating. Although there is much know-how on design, there are few researches on the durability of O-ring rubber products. Hence, it is very important to understand the mechanical properties and durability of O-ring for long-term usage in safety. In this study, we had immersed several kinds of commercial O-rings with the same size and different components into hot water with and without aqueous chlorine solution for up to 18,000 h. And we tried to apply a compressive load test for the O-ring rubber in order to evaluate the mechanical properties after the accelerated degradation test. From the result, it was found that the compressive load for the displacement of O-ring immersed into chlorine-containing hot water indicated severely degradation as compared with that of O-ring immersed into hot water. In addition, it was also found that the measurement result of compressive load sensitively indicated the same tendency with the result of compression set test.
Effect of Screw Geometry on Long Glass Fiber Breakage during Injection Molding
The aim of this work is to compare the effects of two different 40 mm screws on fiber breakage during plastication. A polypropylene, reinforced with 30% long glass fibers, was tested. A standard three zone screw and a special profile screw were compared. The special screw has low compression ratio, a dynamic mixer and it is tapered over the whole length. The pitch is variable, increasing from the feeding zone to the screw front; the combination of these features gives higher productivity with better melt homogeneity and a very consistent dosing time end cushion. The plastication was performed at two different process conditions and the screw pull-out technique was used. The fibers length was measured at different distances from the hopper after the matrix pyrolysis. The experiments show that the different geometry of the screws, within the selected conditions, did not affect the fiber breakage. Residence time and aspect ratio of pellet length to channel width and length were also considered. A procedure was developed and validated in order to allow an accurate comparative analysis of the fiber breakage progression during plastication.
Grain Development & Grain Repair on a 7,Xxx-Series Aluminum
Engineers at GM have been developing an injection mold tooling strategy based on the use of aluminum to meet low, medium, and high volume production part requirements. This scalable tooling strategy marries the appropriate aluminum with the appropriate tool construction to satisfy production demands while minimizing tooling capital investment and piece price. Implementation has required engineers to overcome both cultural prejudices against the use of aluminum and technical roadblocks like the ability to grain a part?s surface. This paper reviews the work accomplished by GM and Alcoa in regards to grain development and repair on a 7,XXX-series aluminum, QC-10.
Direct Fiber Feeding Injection Molding of Glass Fiber Reinforced Polyoxymethylene/Poly (Lactic Acid) Blend Composites
In this study, the short glass fiber reinforced POM, PLA and POM/PLA blend composites were fabricated by a direct fiber feeding injection molding. The glass fiber contents were controlled by the matrix feeding speed. The mechanical properties were investigated by tensile testing method. It was found that the tensile modulus of all composition increased with increasing glass fiber content by the results of POM/PLA blend composites indicated the intermediate value between PLA and POM composites. Tensile strength of POM/PLA blend increased nearly the same with POM composite at low glass fiber content. The critical fiber length that was calculated by modified Kelly and Tyson`s equation was used to calculate interfacial shear strength. The critical fiber length of them did not change significantly. However, PLA composite has a high interfacial shear strength even all of them revealed a fair interfacial adhesion between glass fiber and matrix that were observed by scanning electron microscope.
Nylon in Automotive ? Four Case Studies
Nylon is a Polyamide (PA) that has been used for many years in automotive components due to its good balance of cost and performance. One drawback with nylon is its moisture absorption. After an introductory discussion, several case studies are presented where the moisture affinity of nylon was an issue in the development and testing of automotive components. One case involves a toughened nylon, a second involves a 50% glass filled nylon, a third involves a plasticized, toughened nylon and the fourth and final case reviews an issue with a decoratively coated nylon part. The focus in all cases is on one or the other of the two most common nylon materials, nylon 6 (PA6) and nylon 66 (PA66). Engineers need to be aware of potential moisture issues very early when designing parts and test programs with nylon materials.
Percolative Multilayered Dielectrics with Confined Alignment of Conductive Particles
Percolative dielectric composites are currently high-profiled due to the ultrahigh permittivity. However, the undesired giant loss and ultralow breakdown strength greatly inhibit the applications in energy field. By replacing the surfacial modification methods by a convenient route, conductive particles were alternately aligned in separate layers in this work. Polyvinylidene fluoride (PVDF)-based multilayered dielectrics containing confined carbon black (CB) were fabricated using a layer-multiplying extrusion. For a given thickness, the dielectric permittivity significantly enhanced with the layers. At the layer number of 256, the permittivity at 103 Hz became 6 times higher than neat PVDF. Furthermore, the presence of barrier PVDF layers distinctly improved the breakdown strength by hundreds times compared with PVDF/CB conventional composite at same loading. The present approach significantly broaden the choices of dielectric materials for new generation clean energy applications.
The Effect of Hydroxyapatite Surface on Osteo-differentiation of Human Mesenchymal Stem Cells using Serum Free Media
The manner by which human mesenchymal stem cells (hMSCs) are influenced to differentiate is an area that has been intensely studied. In this study we have observed that the in vitro biochemical differentiation of hMSCs was inhibited on a lamellar hydroxyapatite surface. hMSCs were differentiated on standard tissue culture treated 24 well plates and also on
hydroxyapatite coated plates using osteogenic serum free media. It was found that hMSCs did not differentiate into osteocytes under any conditions using serum free media on the hydroxyapatite coated plates, while differentiation of the cells did occur when tissue culture plates were used. Some mechanistic investigations were conducted to determine the cause of this inhibition. As of this writing it is difficult to assign a single root cause for this result, but depletion of calcium and phosphorous levels over the hydroxy apatite surface may play a role.
Fracture Behavior of PA6 Rubber Blends Influenced by Water Absorption
It is well known that the properties of polyamide 6 (PA6) can be strongly influenced e. g. by either blending with a rubber phase, by water absorption or by a combination of both. The fracture behavior of PA6 and PA6 blends can be evaluated more thoroughly, when using the method of essential work of fracture (EWF) and the ductility level as evaluation criteria. In this investigation, differences in the blend morphology between a dispersedly dissolved rubber phase and a co-continuous morphology were detected by means of the method of EWF. An initial raise in the specific essential work of fracture in comparison to the dry-as-molded state caused by low moisture absorption, is followed by a drop with further increasing moisture. In contrast, the specific non-essential work of fracture is only influenced by a higher moisture uptake.
Effect of Varaible Fiber Orientation on Material Properties in Extruded Polymer Composties with Multi-Scale Additives
In this experiment, carbon microfibers and multi-walled carbon nanotubes were compounded into a poly-butylene terephthalate polymer matrix. PBT-based composites were compounded in a co-rotating non-intermeshing twin-screw extruder with various fractions of carbon microfiber and multi walled carbon nanotubes additives. In addition, two dies ? straight and divergent ? were used to explore differences in physical properties.
Mechanical and thermal properties were tested and the results compared for straight and divergent dies. Optical images were analyzed to study the behavior of microfibers in flows through straight and divergent channels. A correlation was shown between the die type, the structure in the optical images and the physical properties.
Degradation Analysis for Polyethylene of Raised Temperature Resistance after Long-Term Hot Water Immerssion and Hot Air Exposure Tests
Polyethylene is widely used as a lifeline pipe for water and hot water supply plumbing in domestics. Recently, plastic pipes are required the performance of not only long service life but also recyclability. Non cross-linked polyethylene with durability and recyclability are beginning to use for heating pipes, for instance the polyethylene of raised temperature resistance (PE-RT).It is meaningful that the degradation of the PE-RT mechanism at high temperature is revealed for developing higher durability pipes and diagnosing used pipe?s deteriorations
In this study, as non-cross-linked polyethylene acceleration testing of PE-RT test piece was performed for long term under hot water and air condition to clarify the degradation state chemically compared with mechanical and anti-oxidation properties. FT-IR and Raman mapping method was used to examine the distribution of oxidation state, anti-oxidant additives quantity and crystallinity. The oxidations of polyethylene were not found, but anti-oxidant additives were remarkably reduced, which coincided with oxidation induction time (OIT) decrease. It was found particularly in about 80 ?m from the surface of only hot water test samples, the reduction was accelerated because of the elution to hot water. The tensile strengths were increased compared with initial and almost the same regardless of test times. The heat of fusion varied similarly with the tensile strength, which means thermal crystallization. On the other hand, tensile elongations at break were slightly reduced at long time. It was found the dispersion degree of crystallinity was bigger over test time from the analysis of Raman peak intensity ratio (crystal to amorphous) and the dispersion in hot air are remarkable. This inhomogeneous crystallinity is assumed to decrease the elongation by deformation or defects in micro region. |
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