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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High Performance High Density Polyethylene (HDPE) for Hot Fill Closure Applications
High performance bimodal high density polyethylene (HDPE) was developed for the hot fill closure applications. Performance of the bimodal HDPE was benchmarked versus incumbent unimodal HDPE resins. The bimodal HDPE resin delivered better environmental stress cracking resistance (ESCR) than a conventional HDPE homopolymer while maintaining a good heat deflection temperature (HDT) and a good Vicat softening point. The high performance HDPE also exhibited greater shear thinning behavior, indicative of good processability under the high shear rates typically encountered in the injection molding process. In addition, the closures made from the new HDPE resin are advantaged with respect to the removal torque.
Comparative Testing of Pre-Pigmented and Natural Compound plus Black Coloring Master Batch HDPE Pipes for Potable Water Applications
A study was initiated to demonstrate that the use of HDPE natural compound plus coloring master batch can be used to meet the requirements of ISO 4427:2007 potable water pipe standard. A test matrix was developed to evaluate a pre-pigmented black HDPE compound and two versions of blended natural compound plus black coloring master batch for conformance to the requirements in three different parts of ISO 4427:2007. One blend version used a typical North American black coloring master batch with a nominal carbon black particle diameter of 58 nm. The other blend version evaluated a black coloring master batch that met the ISO 4427:2007 carbon black average particle diameter requirement (10 – 25 nm). 110 mm PN16 pipe (standard dimension ratio of 11) was produced from all three materials using the same extrusion equipment, temperature profile and extrusion rate. The results of the conformance testing are discussed as well as recommended steps for the use of natural compound and coloring master batch in regions of the world with experience in pre-pigmented HDPE pipe compounds.
Enhancement of Paint Adhesion with Polyolefin Blends
Adhesion of coatings to molded polyolefin articles is a well-known challenge due to the low surface energy of polyolefin materials. This study examines the influence of substrate composition and morphology on adhesion. It has been observed that the composition of the substrate plays a role in the adhesion performance of paint systems due to changes in the surface morphology and chemistry. By engineering the surface morphology of the molded polyolefin, adhesion of paint can be significantly improved and may ultimately lead to a path for low cost, facile decoration of materials in markets where they are currently not in use today.
Influence of Elastomer on Morphology and Mechanical Properties of Nylon 6/OMNT/Elastomer Composite
Nylon 6/OMMT/elastomer composite was first prepared by molten compound method and then how its rheological properties, mechanical properties, micro morphology and the shape of fracture surface vary with elastomer content was investigated. The results indicate: With the increase of elastomer content, impact strength increases significantly, tensile strength, flexural strength and modulus decline and elongation at break declines first but then increases?the SEM images of fracture surface go well along with the results of impact tests, and critical matrix thickness for the composite materials of brittle ductile transition layer is 0.14?m. With the increase of elastomer content, the apparent viscosity increases first but then declines, non-Newtonian index declines and the activation energy declines first but then increases. So adding elastomer makes it possible for Nylon 6/OMMT/elastomer composite to flow steadily in a wide temperature range under a constant shear stresses and makes the composite easy to fabricate.
Microscopy of Intentionally Oxidized Polypropylene-Based Mesh Material
Surgical mesh and sutures made from polymer materials have long been utilized as medical devices. Several polymeric materials have been employed to manufacture these devices, including polypropylene. PROLENE® fibers, comprised of polypropylene-based material with added antioxidants, pigment, and processing aids are fiber spun and used in medical sutures and pelvic mesh implants. Claims of in vivo degradation of mesh devices, including PROLENE®, have been investigated by others [1-7]. Surgical mesh is typically surrounded by tissue during and after implantation. Histological dyes such as Hematoxylin and Eosin (H&E) can be used to stain surrounding tissue on explanted devices. Using optical microscopy, we demonstrate that non-implanted, intentionally oxidized, PROLENE® fibers do not stain with H&E. The inability of PROLENE® to become stained is an important finding as it provides histologists and others a means of delineating between biological material surrounding mesh and the fibers that are used to construct the mesh.
Modern Fabrication of Poly(Lactic Acid) Nanofibers by Cotton Candy Method
Poly(lactic acid) (PLA) nanofiber was prepared using cotton candy method. The nozzle temperatures were varied from 210-260 °C. PLA was fed to extruder then melted PLA was accelerated through small nozzles by hot air pressure. The effect of nozzle temperatures and air pressures on morphology, an average diameter and thermal properties of PLA nanofiber was determined. SEM results suggested that PLA fibers were straight and smooth at low nozzle temperatures. The diameter of fibers decreased with increasing the nozzle temperatures with regardless on the air pressures. MFR and thermal properties informed that PLA degraded at the nozzle temperature higher than 230 °C. The optimized condition was fallen at the nozzle temperature of 250 C with air pressure of 0.2 MPa. The average diameter was around 500 nm at the productivity of 140g/h.
Bridging the Gap: Liquid Solutions for Joint Sealing
Adhesive sealants are used to seal a surface and prevent the passage of a liquid or gas. Henkel’s innovative industrial sealants are the result of consultations with industry experts and the company’s analysis of realworld production environments. Maintaining or improving efficiency is Henkel’s primary focus; making sure our industrial sealants work right the first time and every time. There is a multitude of sealing applications that arise in practice. The most common sealing applications suited for adhesives are gasketing and seam sealing. Henkel also provides solutions for more niche applications such as weld porosity sealing or casting porosity sealing.
Time Is Money: High Speed Adhesive Solutions for Instant Bonding
Over the last century, cutting down manufacturing costs and time using faster assembly methods has been a high priority for many companies. Bonding methods that are reliable, as well as easy to use and automate cut down on these added expenses associated with assembling and manufacturing products. Advancements in adhesive technologies, included improved performance cyanoacrylates, the development of hybrid structural instant adhesives, low pressure molding adhesives as well as polyurethane reactive hot melts have allowed instant bonding to outperform mechanical and thermal joining methods by providing reliable, repeatable bonds for virtually all substrates on a fully automated production line.
Fabrication, Morphological Evaluation, and Characterization of Semiconducting Oxide Nanofibers from Gas Jet Fiber Spinning Process
In this paper, we report that Gas Jet Fiber (GJF) spinning is an efficient process to fabricate sub-micrometer and nanometer sized single or bi-component semiconducting metal oxides (SMO) fibers with different morphological forms like mesoporous or solid cylindrical, core-shell (CS) and side-by-side (SBS). SMO fibers with tailored morphology are fabricated via GJF spinning from polymer template in conjugation with conventional precursor solgel chemistry. The GJF-spun fibers are systematically characterized using SEM, TEM, EDX, N2-BET surface analyzer, and XRD for their morphological and crystallographic studies.
Characterization of Polypropylene/Bamboo Fiber Composites Modified with Polyethylene Grafted Maleic Anhydride
Bamboo fiber (BF) was compounded with polypropylene (PP) in twin screw extruder at bamboo fiber contents of 0-30 wt% with linear low density polyethylene grafted maleic anhydride (LLDPE-g-MA) as modified agent. PP/BF composites were fabricated to dumbbell specimens by injection molding. The effect of bamboo fiber contents on mechanical properties, fracture toughness, morphology and thermal properties of PP/BF composites was investigated. Tensile and storage modulus of the composites increased when increasing bamboo fiber contents. It can be noted that bamboo fiber promoted crystallization and enhanced crystallinity of PP in the composites, which improved the composites mechanical performance. On the contrary, tensile strength of the PP/BF composites was almost unchanged. It can be noted that fracture toughness of the PP/BF composites was maintained at the BF contents of 10 wt%, which was attributed to the good interaction between bamboo fiber and PP matrix with the addition of LLDPE-g-MA.
Effect of Anhydride Type on Structure and Thermal Properties of Poly(Propylene Carbonate) Composites Produced by Reactive Extrusion
Poly(propylene carbonate) (PPC) is an environmental friendly thermoplastic aliphatic polycarbonate. To broaden the application of this material, three types of anhydride (maleic anhydride (MA), phthalic anhydride (PA) and pyromellitic dianhydride (PMDA)) were melt blending to end-cap PPC by reactive extrusion. FTIR, Raman spectroscopy, TGA, and intrinsic viscosity test were used to characterize structure and properties of anhydride end-capped PPC. Results indicate that the reaction mechanism between PPC with MA was different from PPC with PA and PMDA. Intrinsic viscosity test demonstrates that molecular weight of PPC-PMDA was higher than that of pure PPC. In addition, TGA results show that the thermal degradation temperature of PPC could be improved by adding three types of anhydride, and the T-5% of PPC-PMDA was the highest and increased by 26.3 ºC.
The Surface Resistance Value and Physical Properties of Conductivity Fiber Filler-Compounded PES
Although the high-strength resin has been developed as a metal substitute, many resins are mostly to be an insulator that does not conduct electricity. There is a tendency for hoarding the static electricity. Therefore, highly conductive metal is used as jig and parts that related to precision parts of vehicle mounted.
PES (polyether sulfone) is an amorphous plastic, which is high heat resistance. In order to impart conductivity, the conductive filler and PES were compounded and measured the surface resistivity and physical properties.
Effect of Minerals on Rheological and Thermal Behavior of PLA/PMMA Blends
This study presents the rheological and thermal behavior of mineral reinforced Poly(lactic acid)/Poly(methyl methacrylate) (PLA/PMMA) blends prepared by melt processing. In particular, combinations of amorphous or semi-crystalline PLA with high or low viscosity PMMA were used to prepare the blends. The effect of the addition of three commercial minerals, clay, calcium carbonate and quartz, was investigated. The glass transition, crystallization and melting of these blends were examined by differential scanning calorimetry. The blend rheology was investigated by small amplitude oscillatory shear rheology. Miscibility was inferred from the shift in glass transition temperature. A single glass transition temperature was observed for all blends indicating initial miscibility of the PMMA/ PLA blends over the entire composition range. This observation was reinforced by the fact that the mixtures remained transparent. It was however possible to induce a phase separation when placing the blends in conditions that favored PLA crystallization. The ability of PLA to crystallize was strongly restricted by the presence of the amorphous PMMA fraction but remained possible in selected conditions. All binary blends showed a typical viscoelastic behavior with a Newtonian plateau at low frequency range. However, the filled blends showed an increase in viscosity at low frequency typical of materials exhibiting a yield stress.
Simulation of Co-Rotating Fully Intermeshing Twin-Screw Compounding Extruders: Alternatives for Process Design
The co-rotating fully intermeshing twin-screw extruder is the primary production unit for compounding polymer based materials. It also has had a long term presence in processing material in the chemical and food industry and more recently in pharmaceuticals. The layout of a co-rotating twin-screw compounder for a specific processing task is primarily based on 1) the experience of the process development engineer and 2) tests run on a lab-scale unit. Additionally, scale-up to a much larger extruder is very often required as part of the development process. Traditionally this scale up has been based on experience and classical scale-up rules.
In addition to experience and lab tests, good simulation software can help guide the development engineer in the design of initial compounding extruder configuration as well as scale-up to a commercial unit. The overall objective being to minimize risk (cost). Know-how based on experience, trials in the laboratory, production and simulation software are the preferred combination for the layout of an extrusion process.
A New Evolution Equation for Polymer Coils with Non-Affine Rotation
When applied to shear flow, Maxwell-type constitutive models typically over-predict shear thinning. For many known models such as the Leonov model, the slope of the viscosity vs. shear rate plot in log-log scales converges to -1 at high shear rate. This is not realistic for polymer melts and concentrated solutions. In this work, rotational retardation is introduced to the evolution equation so that rotational ‘softening’ can be better controlled in rotational flow such as shear flow. The new evolution equation involves a new parameter n to control the affine advection of rotation so as to adjust the degree of shear thinning or thickening. In combination with finite stretch, a five-parameter nonlinear viscoelastic fluid model is proposed. The resulting constitutive model is suitable to describe the deformation of polymer coils and demonstrates excellent data fitting capability to realistic rheological data for both shear and extension.
Solid-State Foaming of Polylactic Acid-Hexagonal Boron Nitride Composites to Fabricate Thermally Conductive Foams
Micro-and-nano-electronic devices are prompting for new demands in light-weight and flexible multifunctional materials, including those for thermal management applications. In this context, this study presents a new industrial viable processing strategy to develop and fabricate light-weight thermally conductive polymer composites, through physical foaming, with reduced filler loadings. While foams are known for their good thermal insulating properties, experimental results revealed that foaming-induced filler reorientation would help to partially compensate the negative impact made by the voids on the composite’s effective thermal conductivity (keff). As a case example, thermally conductive PLA-hBN composite foams were fabricated by solid-state carbon dioxide foaming. With a filler loading of as little as 10 vol.%, the PLA-hBN composite foam’s keff was about 3.5 times higher than that of neat PLA.
Electrical Conductivity and Humidity Sensing Properties of PVA/CNT Nanocomposites
In this study, multi-walled carbon nanotubes (MWCNT)/polyvinyl alcohol (PVA) nanocomposite films were fabricated and characterized. The effect of MWCNT loadings in the insulating PVA matrix and the influence of relative humidity on the electrical conductivity of the nanocomposite were investigated. The results of different measuring techniques were also characterized and compared together. Experimental results of this research revealed that the electrical conductivity of 1 wt.% MWCNT/PVA nanocomposites increases up to six orders of magnitude by increasing the relative humidity from 0 to 80 percent. This characteristic demonstrates the potential of using MWCNT/PVA nanocomposite thin films in moisture sensing applications.
Accounting for Pressure Dependent and Elongational Viscosities to Improve Injection Pressure Predictions in Mold Filling Analysis
The increasing demand for shorter product development timelines and more robust plastic part designs has made injection-molding simulation a critical tool for plastic part and mold designers. One of the most common objectives of injection-molding simulation is determining the pressure requirement to manufacture the part for a given resin and set of process parameters. The reliability of injection-pressure prediction is dependent on many factors including accurately modeling the part and mold geometries, and predicting the material behavior during this dynamic process. While advancements have been made with regards to improving the ability to properly represent the mold and plastic part geometries, the ability to adequately model the molten polymer behavior remains a difficult task. Of particular importance is the ability to properly characterize the material viscosity during the injection molding process. The ability to account for the effects of pressure and elongation deformation on the material viscosity is critical for providing reliable injection pressure predictions. This paper will present the results of an experimental validation study in which the effect of accounting for the pressure dependence and elongation deformation on the material viscosity influences the injection pressure predictions.
Fast Prediction of Crystallinity in Injection Molding during the Packing Stage
Being able to predict products’ degrees of crystallinity, and thereby optimize their crystallization processes, is of great significance for producing high quality polymeric products in injection molding. Injection molding simulation software can simulate polymers’ density results during the packing stage, and these predicted density results can be used to calculate polymers’ crystallinity results. Based on this idea, a novel method was proposed to predict the degree of crystallinity for polymers during the packing stage. For this method, pressure and temperature results were first simulated using injection molding simulation software, and then the density results were calculated based on a pressure–volume–temperature (PVT) model. Next, the crystallinity results were solved according to the densities of the fully crystalline part and the purely amorphous part. Finally, a real part in production was conducted as a case study to verify the proposed crystallinity prediction method. Experimental results showed that the proposed method was both correct and effective.
Automotive Glazing – Polymeric Systems Providing Enhanced Design Freedom and Functionality
Automotive glazing using engineering thermoplastics (ETP) is an area of immense interest for the automotive industry as it provides unique opportunity to redefine the overall appearance and styling of the vehicle in addition to light weighting. Typical transparent parts seen on a car such as the side moving windows, rear windshield, rear quarter windows (RQWs), panoramic sunroof and the lift-gate (or tailgate) are traditionally made of tempered or laminated glass. Use of ETP materials that are transparent like polycarbonate (PC) can offer comparable functional performances at reduced system cost in addition to significant weight reduction. Such parts made of PC are virtually unbreakable, have good weatherability and scratch resistance imparted through proprietary surface coating technology. The advanced molding process used to manufacture such large transparent part is termed as 2-shot injection-compression colding (2K-ICM). This paper focuses on identifying the critical molding process variables and capturing their effect on the final part quality. The emphasis is on minimizing the combined part warpage and maintaining lower levels of residual stress in the part. By performing a simulation-based design-of-experiments (DOE) study, the relationship between the process parameters on the part warpage is elucidated. Finally, through a regression analysis, an estimate of the warpage is made using the mathematical model.
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