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.
Infrared temperature sensors were used to study the effect of mold rotation technology on the plastic melt temperature and shear-burning that commonly occurs with PVC. Inserts were designed and built so that areas of high shear could be introduced during flow through a runner, as well as provide for the incorporation of melt rotation technology. A DOE was used to investigate how factors such as melt temperature, residence time, injection rate, and packing rate affected the temperature at various points along the flow path. It was found that the use of melt rotation technology could allow more uniform temperatures after the point of rotation without causing a larger problem with shear-burning.
In this paper we present the potential of applying buckypapers (BP) films for the improvement of the interlaminar fracture toughness of laminated composites. We experimentally investigated the effect of interposing BP between plies on the interlaminar fracture behavior of glass fiber / epoxy woven fabric composite laminates. Crack propagation was examined during mode I - fracture testing using double cantilever beam (DCB) specimens prepared with different types of BP placed at the midplane.
While lower fracture toughness values were determined when using BP prepared with untreated carbon nanotubes (CNT) and graphene nanoplatelets (GNP) - CNT/GNP – (hybrid filler at a weight ratio CNT/GNP=80/20), a slight increase in toughness was observed employing BP prepared with oxidized CNT (CNT-ox). Morphological analysis of the fracture surfaces indicated that this increase in toughness was related to fracture phenomena that were enabled by the presence of BP film. Cohesive failure of the BP film and fiber bridging positively contributed to the increase in toughness observed in the case of composites reinforced with BP-CNT-ox.
The adhesive failure mode of BP-CNT/GNP was different from the cohesive mode characteristic of BPCNT- ox, indicating the importance of promoting cohesive failure of the BP, as it enables a more effective energy dissipation mechanism.
This research is concerned with creating an antibacterial wound dressing material by introducing naturally-derived chitosan into thermoplastic polyurethane (TPU) matrix. Chitosan is a promising filler to improve the antibacterial properties of wound dressing materials including TPU. A combination of chitosan with cellulose nano-crystals (CNCs) can help meeting the mechanical design requirements of wound dressing applications. TPU nanocomposites modified with CNCs were prepared by using an optimized solution casting method. Morphological analysis carried out through scanning electron microscopy (SEM) showed that CNCs are well distributed within the matrix up to a filler amount of 2wt%. Thermal analyses indicated that the incorporation of nanofillers leads to significant changes in the glass transition temperature and melting behavior characteristic of the hard segments. Rheological analyses performed on molten TPU incorporating CNCs indicated that the presence of the filler favors shear-thinning behavior.
TPU films containing a combination of CNCs and chitosan were made through a solvent exchange method and solution casting. Current investigations are focused on the characterization of the mechanical properties, water absorption behavior and water-responsive mechanically adaptive properties of the hybrid TPU-CNC-chitosan composites.
Since the downturn of 2009, there have been a number of developments that have caused us to question the value of a Liberal Arts education in our country. The events of the last year including free speech on college campuses and the high level of debt of college graduates plus the personal experience of seeing college again through the eyes of our children has inspired this paper.
Manufacturing has an opportunity to grow again in this country but the level of skilled personnel is diminishing. This gap in talent threatens the revival of manufacturing in the USA. What can be done in our education system to meet this gap or need?
Injection molded glass fiber reinforced polypropylene (GFPP) was immerged into hot water and its bending test was carried out to study about degradation of GFPP caused by water absorption. Although the water absorption of GFPP is low (about 0.2 wt%), it shows obvious decrease both in flexural modulus and flexural strength. Flexural strength decreases with the immersion time continuously, while flexural modulus shows rapid decrease during early period of immersion and then become constant. Another experiment in which the specimens were dried after immersion shows the flexural modulus after the early drop correlates with amount of water absorption and recovers by drying to the same level of immersed samples having the same amount of water absorption. That indicates there are different mechanisms while flexural strength decreases as a result of some irreversible degradation during water immersion, flexural modulus is just due to a reversible swelling by water absorption. And the rapid drop of modulus seems to be not caused by water absorption but by heat.
A method has been developed to study the performance and suitability of thermoplastic polymeric material for Additive Manufacturing (3D-printing) based on Fused Deposition Modeling (FDM). The method has been used to study the benefits of minerals for PLA-based material (filaments) that are commonly used in FDM 3D-printing. An optimized formulation has been presented that enhances the printing performance and print quality, reduces warpage and curling of the edges, and allows 3D-printed PLA objects to be annealed while maintaining their original shape and dimensions. The annealed PLA objects show significantly improved heat/temperature resistance and can withstand temperatures as high as 120ºC.
Poly(ethylene terephthalate) (PET), with its high dielectric breakdown strength, is widely used in multilayer PV module backsheets as a core layer. However, it degrades due to ultraviolet light and humidity. Failures such as cracking and delamination in backsheets caused by weather-induced degradation may result not only in performance loss of the modules, but also loss of electrical insulation, which is a safety concern. Degradation of different grades of PET and two types of backsheets were studied and modeled under multi-factor accelerated weathering exposures. The formation of light absorbing chromophores, changes in the fundamental absorption edge of the polymers, and UV stabilizer bleaching were confirmed through UV-Vis optical spectroscopy. FTIR-ATR analysis showed that chain scission is the common mechanism under all exposure conditions. The degradation mechanisms determined from optical and chemical evaluations were then used to construct a set of degradation-pathway network models using semi-gSEM (semi-supervised generalized structural equation modeling) methodology using a
Glycerol-plasticized soy protein isolate (SPI) films with dialdehyde carboxymethyl cellulose (DCMC) as crosslinking agent were solvent casted and tested for their mechanical properties. Results indicate that the addition of DCMC increased tensile strength (TS) up to 218%, suggesting effective crosslinking between SPI and DCMC. The significant improvements in the TS compared to other dialdehyde polysaccharide crosslinking agents such as the dialdehyde starch is due to higher compatibility of DCMC with SPI, which was confirmed by SEM imaging. Furthermore, based on stress-strain features, a hypothetical mechanism was proposed to illustrate the effect of the polymeric cross-linking agent.
Two of the most common industry methods for evaluating the pressure drop through an injection mold during mold filling are investigated against an instrumented mold. The first is injection molding simulation and the second is the shop floor applied “Pressure Drop (Loss)” study method that is widely accepted as part of modern injection molding practices. The study finds that the shop floor method can significantly misrepresent the relative pressure developed through progressive regions of a mold. Injection molding simulation was found to provide a better agreement with the actual measured mold filling pressures.
An intravascular catheter system requires design specifications that needs to provide sufficient flexibility, to follow desired path required by the surgeon and adequate stiffness to travel along the curving path of vasculature. This paper presents the effects of sub-supercritical, near-supercritical and beyond supercritical carbon dioxide assisted extrusion process and their characterization to evaluate their thermal and dynamic mechanical properties using Pebax. A twin-screw-extruder using scCO2 can effectively generate foams, while providing excellent control over mechanical and thermal properties. The crystallization and melting behaviour of scCO2 assisted extrudates were investigated using differential scanning calorimeter technique (DSC) for various isothermal conditions. The mechanical performance was evaluated by using dynamic mechanical thermal analysis (DMA) and tensile test. A significant increase in dynamic modulus was observed for Pebax extruded at 800 psi and 1000psi, however, decreased resilience and toughness was noted for Pebax extruded at 1200psi.
Conventional polyamides with high relative viscosity called “high RV polyamides” or “high RV nylons” are prepared typically by a few large nylon-6 producers with solid state polymerization (SSP) process, which is time consuming and energy intensive and hence expensive. Such polyamides are linear molecules as are high RV polyamides produced by compounding with chain extenders with ?-? functional groups. However ZeMac® alternating copolymers of ethylene and maleic anhydride, which are unique with hundreds of pendant functional groups, can be compounded with low RV polyamides to form high RV polyamides which have a branched structure, confirmed by shear thinning rheology. The paper will cover this and performance and cost advantages of such branched polyamides over conventional SSP and linear polyamides for several high performance applications.
Emergence of bovine spongiform encephalopathy (BSE) has inhibited the use of proteinaceous materials from rendering industry with regard to animal feed, pet food, and fertilizers. In recent times, extensive research has been done towards finding suitable, alternative, non-feed and non-fertilizer applications for these materials. In this regard, plastics from proteins, especially thermoplastics and derived composites, have emerged as a potentially suitable choice. However, poor mechanical properties, high moisture absorbing ability as well as inherit odor have limited their widespread application. In this study, we developed high-strength, and toughened thermoset polymers from proteinaceous material obtained from the rendering industry, such that they can be employed in high performance applications, such as automotive sector.
Multifunctional fiber reinforced epoxy composites with improved sand erosion resistance; mechanical properties and electromagnetic interference (EMI) shielding resistance have been fabricated and tested in this work. Preformed carbon nanofiber (CNF) thin film or nanopaper, made of dense and entangled nanofiber networks, was laminated on the surface of glass fiber reinforced epoxy composites (GFPRC) as a surface protection layer. Five times improvement in sand erosion resistance in terms of sand erosion rate, and up to 24% improvement in flexural strength was achieved after the incorporation of CNF nanopaper onto thin glass fiber/epoxy composite. The CNF nanopaper composite showed an EMI shielding resistance of 30–40 dB within a frequency range of 30 MHz to 1.5 GHz. This multifunctional composite material shows good potential for use in commercial electronics, housing, and the automotive industry.
This report describes the results of a project focused on obtaining the yield stress at the weld bead of a vibration welded pressure vessel. The burst pressure of 0.508 bar was obtained from the hydrostatic pressure test data performed experimentally. The aim of this project is to verify the amount of stress generated at the weld bead as it is observed in the hydrostatic pressure test that the rupture occurs in this region and formulate a failure criterion. Additionally, the project investigates the best methodology of mesh by playing with the various parameters like geometric modelling, order of elements and type of contact in Hyper mesh 13.0 in order to obtain maximum correlation with experimental data. The material used for the vessel is Thermylene (a polypropylene composite material which is proprietary to Asahi Kasei Plastics NA) and a bonding resin compound for the bead. The analysis consists of Non-Linear Geometric Static simulation of applying 0.075 MPa of pressure (to get more data points in yield condition and observe geometric behavior) to the vessel using Finite Element Analysis. Both the full and quarter model was Meshed using Hypermesh and analyzed in ABAQUS. The results obtained from the analysis were displayed using stress plots.
Growing year by year in use as a general purpose plasticizer phthalate replacement, 1,2 cyclohexanedicarboxylic acid diisononylphthalate (referred to generically as DIDC) has limitations in both processing and final product performance. A project was undertaken recently to demonstrate how DIDC’s performance can be improved through the utilization of propylene glycol dibenzoate (PG) in vinyl floor tiles. To demonstrate the effectiveness of adding PG to DIDC for increased compatibility, formulations were prepared containing diisononylphthalate (DINP), DIDC, PG, and blends containing DIDC and PG. The results indicate a marked improvement using DIDC/PG blends in fusion temperature and dry point over standalone DIDC formulations, as well as tensile strength and elongation properties that are comparable to DINP.
The color of a polymeric compound must be engineered just like any other desired resin property such as mechanical or thermal. Reaching the desired color can be adversely affected by processing or the combination with modifiers and additives in the resin system. Even if colors can be achieved by increasing the amount of pigment used in the formulation, other performance attributes such as mechanical properties may be adversely affected as well. This paper discusses these color matching concerns.
Improper rebuilding of screws for injection molding plasticators can lead to screws with high wear rates and the formation of resin degradation products. Resin degradation can cause black specks and color streaks in injection molded parts, reducing the yield and profitability of an injection molding process. This paper presents two problems that occur when injection molding screws are not rebuilt properly.
A novel alternating film/foam multilayer sheet was prepared through multilayer co-extrusion. The film layer was a blend of LLDPE with poly(ethylene-octene) elastomer (POE) and the foam layer was cross-linked and foamed POE. The multilayer film/foam sheet exhibited advantaged acoustical properties. In select wavelength regions, the sound absorption coefficient of the multilayer film/foam structure improved 2-3 times compared with conventional single-layer materials.
This paper deals with the effects of barrel and screw heating in rubber extrusion particularly with regard to the throughput and the melt temperature. To determine exactly the impact of heating on throughput behavior during extrusion, experimental investigations were conducted on two rubber extruders of different sizes. In addition, numerical flow simulations were carried out for non-isothermal shear thinning melt flows, under consideration of dissipative heating in the screw channel.
Chemical modification of poly(lactic acid) (PLA) through a reactive extrusion process was performed in the presence of a free-radical initiator and multi-functional chain extenders. Batch foaming, using nitrogen as the blowing agent, was done at various temperatures to differentiate the effect of chain branching and nucleation on the cell size of reactively modified foams. Depending on the conditions very fine, sub-micron size foams were obtained in reactively modified PLA.
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