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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Effect of Feature Spacing when Injection Molding Parts with Microstructured Surfaces
The effects of microfeature spacing on the replication of thermoplastic elastomer features was investigated using micropillars with two diameters (10 and 20 ?m) and three spacing ratios (0.5:1, 1:1, and 2:1). The tooling and part features were characterized for feature depth and height as well as feature definition using scanning electron microscopy and optical profilometry. Feature spacing significantly affected the replication of micropillars using a thermoplastic elastomer. This replication was competition between cooling and pressurization of the melt. Wider spacing between smaller features allowed cooling in the tooling lands to dominate the feature filling. Higher pressures did not always produce better feature replication, suggesting that cooling effects in the tooling “holes” restricted filling. High pressures also produced surface porosity in the molded pillars.
Comparison of Microstructured Surfaces Using Injection Molding and Nanoimprint Lithography
For the first time, thicker (2.4-mm) polycarbonate and polymethylmethacrylate sheets were employed in thermal nanoimprint lithography. The replication of microfeatures using this process was influenced primarily by imprinting temperature and not by imprinting pressure and time. Imprinting of thicker sheets generally showed the same replication trends as injection molding – i.e., channel depth increased with lower viscosity materials, definition of the channel bottom improved with increased solidification time, and land formation required complete replication of the channels. The higher temperatures in injection molding increase thermal and shear-induced stresses, thus increasing shrinkage and decreasing feature definition.
Quantitative Modeling of Scratch-induced Deformation in Ductile Amorphous Polymers
Scratch-induced surface deformation in polymeric materials is a complex mechanical process due to the rate, time, temperature and pressure dependent behavior of polymers. In this study, attempts were made to quantitatively predict the development of different scratch-induced deformation features of a model ductile amorphous polymer. By including the rate and pressure dependent mechanical and frictional behavior in the FEM model, good agreement has been obtained between FEM simulation and experimental findings. Usefulness of the present numerical modeling for designing scratch resistant polymers is discussed.
Degassing of Residual Monomer during Reactive Extrusion of PA6: Experimental Analysis
Polyamide 6 (PA6) with different molecular weight is polymerized in a twin-screw extruder based on the anionic polymerization. Due to a thermal equilibrium a temperature depending content of 10% (wt/wt) residual monomer remains in the PA6. Product quality requires a monomer content < 1% (wt/wt) A two-step vacuum degassing was adapted to realize an in-line monomer removal. The influence of the main degassing parameters on the amount of residual monomer and the relative viscosity of the PA6 is investigated. It was found, that a two-step degassing and injection of water as entrainer provides a content of residual monomer of 2.1% (wt/wt) based on high molecular weight PA6 and a polymer throughput of 10 kg/h. With decreasing content of residual monomer the melt viscosity increases causing a higher shear energy dissipation and melt temperature. At elevated melt temperatures side reactions and thermal degradation of the PA6 can occur, which were detected by changes in relative viscosity.
The Effect of Openair® Atmospheric Plasma on the Adhesion of UV Curable Coatings to Plastics
Ultraviolet (UV) cured liquid and powder coatings provide plastic part manufacturers with a number of desirable benefits including enhanced appearance, improved performance and various process advantages. At the same time, the rapid film formation and densely cross-linked chemistry that characterize UV curable materials also increases the likelihood of adhesion failures. That these coatings are formulated with little or no solvents makes attaining adhesion even more challenging. This paper examines adhesion problems inherent in UV curable liquid and powder coatings, and explores the tradeoffs associated with popular methods to mitigate adhesion problems. We find that atmospheric plasma treatment provides an especially effective means of improving adhesion of UV cure coatings to a wide range of plastic substrates.
Polylactic Acid-Based Polymer Blends for Durable Applications
Elevated temperature and humidity lead to rapid degradation of polylactic acid (PLA). Consequently, PLA is not used for durable applications since properties cannot be maintained. The effects of blending PLA with polycarbonate (PC), heat treatment, and graphene inclusion were investigated in the presence of high humidity at 50°C. Samples were studied for up to 1 year of equivalent outdoor aging. While crystallization and adding graphene enhance short-term stability, it was determined that PC-rich blends in which the PC encapsulated the dispersed PLA had significantly improved hydrolytic resistance and mechanical properties as compared to both PLA and PLA-rich blends.
Thermoplastic Starch: The Prepation Method
This work presents a systematic study about thermoplastic starches. Corn starch was mixed with 2 and 4 wt.% of carboxylic acid and 20 to 30 wt.% of water. The samples were prepared in an internal mixer coupled to a torque rheometer, and the torque values were monitored during mixing. The specimens for mechanical tests were calendered and cut with a knife. The mixtures were characterized by mechanical testing (tensile strength), scanning electron microscopy, and thermal analysis. The torque curves indicated that the samples with and without adipic acid addition suffer retrogradation. When the water content is increased, the glass transition temperature values decrease because water acts as a plasticizer for starch. The mechanical test results showed that samples with 2 wt.% acid content present the highest values of elastic modulus and tensile strength, and the lowest values of elongation at rupture.
Reproducible Relaxation Spectrum of Polyethylene via Global Log-Polynomial Kernel
Discrete relaxation spectrum of an HDPE sample has been calculated using two different approaches modified from the original BSW spectrum. The spectrum with the global kernel consisting of two log-polynomial components appears to provide a good representation of the experimental data. It results in a more reasonable prediction of properties on the experimentally unreachable frequency range than a truncated 6-point spectrum does. The global kernel approach also shows the potential of predicting inflection points on VGP plots, which are useful to quantify LCB and other molecular or morphological features.
Additive-Assisted One-Step Melt Mixing Approach to Disperse MWCNT into LLDPE
Nanocomposites based on linear low density polyethylene (LLDPE) with multiwalled carbon nanotube (MWCNT) were produced by an additive-assisted one-step melt mixing approach. For this the polymer granules, nanotube powder (Nanocyl NC7000) and 1 to 10 wt.% of non-ionic polyoxyethylene cetyl ethers with different ethylene glycol repeating units were simply fed together in the hopper of a small-scale DSM Xplore 15 twin-screw microcompounder. The MWCNT/LLDPE composites showed excellent MWCNT dispersion and highly improved electrical properties as compared to samples without the additives.
Experimental Investigation on Corrosion Properties of LDS MID for Hearing Aid Applications
The trend towards miniaturization is ever going in the hearing aid industry. The Moulded Interconnect Device (MID) technology can offer the unique possibility to reduce the size of the hearing aids by combining electrical and mechanical functions in the same components. On the other hand, one of the main concerns for MIDs in hearing aids is the corrosion of metal tracks. This paper investigates the corrosion of the MID parts based on different base materials, layer thickness and mechanical wear of the MIDs. The results presented in the paper will be useful for designing MIDs in hearing aids and other electro-mechanical applications.
Optimization of Polyolefin Manufacturing Assets in Changing Economies
Dynamic changes in global and regional polyolefin supply and demand combined with varying feedstock pricing have required strategic decision making by polyolefin manufactures. Polyolefin producers are under continued pressure to evaluate plant closing, product mix, target market and asset optimization. This paper identifies several techniques by which polyolefin manufacturing companies can better manage these changes using advanced on-line Nuclear Magnetic Resonance (NMR) technology. Shared examples from commercial plants will demonstrate how the NMR technology has enabled leading suppliers to improve process operability while reducing grade change costs, site inventory levels and costly off-grade blending.
Effect of Nanoplatelets and Polymer Crystallinity on Moisture Diffusion through Polylactic Acid
Polylactic acid (PLA), a bio-derived biodegradable polymer, is being considered as substitute for conventional non-biodegradable polymers in packaging applications, among other uses. However, it has low barrier properties for gases and water vapor. In this work, the effect of nanoplatelets of nanoclay and graphene has been evaluated on the water vapor permeability through PLA films. In addition, the effect of PLA crystallinity has also been studied. It was found that while both nanoclay and graphene have a significant effect on the water vapor permeability, PLA crystallinity has only a smaller effect.
Inline Seal Failure Detection in Ultrasonic Sealing of Packaging Films
One of the main advantages of ultrasonic sealing is the potential for 100 % process control, by monitoring the process data of the generator for every single sealing cycle. This advantage was the topic of many research projects on ultrasonic welding of plastic parts. For ultrasonic sealing in packaging machines, this potential is often neglected. But especially, packaging applications are the last part of a long process and value chain with many possible influences on the package before final sealing. These influences can change the sealing behavior and may cause insufficient packaging. In this paper it is described how disturbances on the sealing process that are caused by liquids, can be simulated and detected by analysis of the process data from the ultrasonic sealing unit.
Enviromentally Friendly Poly(urea imide) Coating with Remarkable Anti-Corrosion Property and Durability
A novel class of poly(urea imide) (PUI) coatings were successfully prepared by in-situ condensation polymerization, followed by solution casting and thermal imidization. The structure and properties of PUI coatings were controlled by controlling the concentration of co-monomers. The resulting PUI coatings have shown remarkable enhancements in anti-corrosion property and coating durability, determined by direct current polarization (DCP) in 3.5 wt% NaCl solution. The evaluation of coating lifetimes was done by using information obtained from time-based polarization resistance study and the optimized PUI coating has estimated lifetime greater than seven years in sea water.
Surface Modification of Halloysite for Epoxy Nanocomposite Applications
Polymer nanocomposites have been extensively investigated over the past two decades, resulting in a wide range of applications because of their excellent performance. Halloysite, a type of naturally occurring aluminosilicate, has attracted increasing interest in polymer nanocomposite applications, especially for the enhancement of mechanical properties owing the tubular structure of halloysite. Herein, we report a facile approach to achieve a high level of dispersion of halloysite nanotubes (HNTs) in epoxy by treating HNTs with a low concentration (0.015mol/L) of sodium hydroxide (NaOH). The NaOH treatment resulted in the formation of hydroxyl groups on the surface of HNTs, leading to a better dispersion of HNTs in polar solvent and epoxy matrix, which was verified by the Zeta potential characterization. Such a higher level of dispersion and strong interface helped enhance the modulus and fracture toughness of epoxy/HNT ( 5 phr HNT) by and 18% and 43%, respectively, in comparison to the neat epoxy. The dynamic mechanical analysis (DMA) revealed a 13% increment in the storage modulus of the composite at 50 °C. The SEM images of the fractured surfaces further confirmed the better dispersion of treated HNTs in the epoxy matrix, as opposed to the large agglomeration of untreated HNTs in the epoxy nanocomposite.
Innovative Approaches to the Process Definition for the Quasisimultaneous Welding of Polymers
Through transmission laser welding (TTLW) is an established joining process in industry. It is used in the automotive industry, electrics and electronics and medical technology. One possibility to describe the laser process is the line energy. Due to time-dependent heat conduction processes in the joint zone, for quasi-simultaneous welding the line energy is only to be utilized conditionally for the determination of parameters and for the definition of a process window. The aim of this paper is to detect the influences of the individual factors by means of design of experiments (DoE), in order to define a suitable valid and robust process window for TTLW. The users of TTLW shall receive a guideline to define a process window for themselves.
Thermo-Sensitive Copolymers for the Treatment of Arterial Aneurysms
Aneurysms (blood filled bulges in the wall of a blood vessel) are among the most common of all lethal cardiovascular conditions. While open surgery and minimally invasive techniques can be used to treat the condition, treatment efficacy, follow up treatment and subsequent management of the healing process is often hindered by the occurrence of endoleaks; leakage into the aneurysm sack after endovascular repair. Furthermore, accessing specific treatment sites located in regions of complex tortuosity remains extremely challenging. The premise of this research is to determine the feasibility of deploying smart, thermo-responsive hydrogels as ‘filler’ materials which can be applied to the affected site using a novel, minimally invasive, catheter delivery technique; with a particular focus on the mechanical and thermo-responsive properties of said hydrogel materials. Different concentrations of poly(poly(ethylene oxide) and poly(propylene oxide) tri-block copolymers, with varying solution-solvent ratios, were studied using calorimetric and rheological techniques. Results show that specific solute-solvent concentrations have potential for use when coupled with a temperature controlled catheter delivery system. However, optimal temperature control remains challenging.
Why You Should Consider a Contour Printed Package
Contour Print aka distortion printing or preprint is nothing new to the thermoforming industry. We believe every innovative thermoformer has tried registering print at one time or another. What’s different about Contour Print is how it came about and why we think it will become a preferred package for brands, consumers and recyclers. Contour print was developed after attending PackEx, Sustainability/LCA, Product Design & other packaging conferences. Contour print takes into consideration the needs of all parties involved in consumer packaging: brand owners, retailers, consumers, recyclers and converters. By taking prominent recycled material like RPET, standard roll fed thermoforming equipment and adding the distorted printing you get a consumer friendly pack that’s easy to recycle. With public concerns for recycling and consumer confusion, using one material for the entire package greatly reduces this problem. Contour Print also reduces weight by replacing flat printed components with printing that is applied directly to the formed plastic package.
Development of an Absorbable Magnesium-Polymer Fusion Cage for the Cervical Spine
Conventional fusion devices (“cages”) are often used to join two vertebrae of the human spine and generally remain in the body for a lifetime and can theoretically lead to any complications. Therefore, an absorbable hybrid fusion cage consisting of a magnesium skeleton infiltrated with absorbable polymer (poly-?-caprolactone, PCL) has been developed. The primary objective of the cage is to ensure an adequate stiffness of the disc space directly after the operation and to encourage the ingrowth of new bone tissue to secure longlife stability. Once a sufficiently rigid bone connection is formed, the implant should be absorbed. Within this paper results of in vitro investigations of the mechanical properties and of in vivo investigation in blackcap sheep are presented.
Investigation of Degradation Mechanism by Copper Catalytic Activity and Mechanical Property of Polyethylene Pipes for Hot Water Supply
In recent years, polyethylene of raised temperature resistance (PE-RT) type materials have been used successfully in domestic hot and cold water piping systems. PE-RT has a unique molecular structure and crystalline microstructure, which provides excellent long- term hydrostatic strength at high temperatures due to tie molecule entanglement without cross-linking polyethylene chains. However, this is little basic research on the durability and degradation mechanism of PE-RT pipes, i.e. the oxidation mechanism of PE-RT pipes in the presence of active ion such as Cu or Fe. In this study, the oxidation and mechanical properties was evaluated by the acceleration degradation test in the presence of the copper ion. These difference and mechanism are discussed on the basis of the results of tensile test, chemiluminescence (CL) measurement, and scanning electron microscope (SEM) observation.
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