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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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.
Development of Non-Destructive Inspection Method Using Ultrasonic Wave for Degradated GFRP under Chemical Environment
This paper describes the weight change rate and mechanical properties of GFRP after the immersion test in 10% sodium hydroxide and 30% hydrochloric acid solutions and vapors at 40°C. The bending stress and the flexural modulus of the sample immerged in 10% sodium hydroxide solution for one month greatly decreased although these of the sample immerged in 30% hydrochloric acid solution for one month did not change. The generation of the acoustic emission (AE) started early at the bending test for the sample immerged in 10% sodium hydroxide solution. It was also found that there was a large difference of ultrasonic echo level between before and after immerged samples in 10% sodium hydroxide solution.
Influence of Flame-Retardant Materials on the Weld Strength of Plastic Parts
Fire-safety requirements, especially in the transportation and the electronics industries, are becoming stricter and stricter, meaning that more and more plastic materials include flame retardants (FR) among their constituent elements. This FR process is an endothermic reaction combined with intumescence or foam formation. When welding plastics, the welding process involves high temperatures above the plastication temperature of the thermoplastics, which can inadvertently activate the FR-reaction. This reaction can result in a lower welding strength. In this study the activation of FR-reactions in thermoplastic materials and the strength of the resulting joint will be considered. Joints were welded using three of the most commonly used processes in the industry: ultrasonic welding, laser transmission welding and hot plate welding. The results show the influence of the material, the process parameters, the welding process, the temperature and the ratio of FR-material to non-FR-material on the strength of the welded joint. For example, higher temperatures in the hot plate welding process or higher laser energy in the laser transmission welding result in lower-strength connections because of a higher activation rate of the FR-material. However, the FR-material is not activated during ultrasonic welding. Here, the lower-strength connection results from the FR-material as a filler material and not because of FR activation.
Microcellular Injection Molding of Polypropylene and Glass Fiber Composites with Supercritical Nitrogen
Microcellular injection molding of polypropylene and glass fiber composites (PP-1684/GF-950) was performed using supercritical nitrogen as the physical blowing agent. Based on design of experiment (DOE) matrices, the influences of GF content and operating conditions on cell structure, GF orientation and mechanical properties of molded samples were studied systematically. The results showed the cell morphology and GF orientation of foaming parts were definitely influenced by the cooling and shear effects. The mechanical properties of foamed PP/GF composites could be effectively enhanced by improving the cell morphology, dispersion state and orientation of the GF at optimal weight percentage wGF/wPP=11.8%. And the optimal conditions for injection molding were obtained by analyzing the signal-to-noise (S/N) ratio analysis of the mechanical properties of the molded samples, which were a shot size of 36 mm, a supercritical N2 weight percentage of 0.4%, an injection speed of 52 mm/s, a melt temperature of 190 °C, and a mold temperature of 70 °C. The molded specimens of PP-GF composites, produced under those optimal conditions, exhibited very uniform fiber dispersion and microcellular structures with an average cell size less than 30 ?m. And the mechanical properties normalized by weight ratio of the microcellular samples were increased significantly, especially the impact strength.
Comparative Analysis of a Novel Clear Polypropylene Impact Copolymer for Use in Thin-Walled Injection Molding
A new technology from Braskem extends the use of clear polypropylene for thin-walled injection molding applications. Typical high melt-flow rate random copolymers have very poor impact resistance at low temperatures, and commercially available impact copolymers produce opaque containers. A new developmental grade from Braskem, PRISMA 1911, was developed to have high melt flow, relatively high stiffness, high impact, and excellent transparency. The goal of this paper is to compare this new grade with conventional impact copolymers, with random copolymers, and with blends of random copolymers and polyolefin elastomers.
Creep Rupture Failure under Conditions of Static Strain
The response of polymeric materials under long-term loading will vary due to several interrelated factors including time, temperature, and the magnitude of loading experienced by the material. A common failure mode encountered in plastic parts under long-term loading is creep rupture. Creep rupture describes a slow-crack growth failure in polymeric parts that is a consequence of molecular disentanglement over time as a result of exposure to continuous stress. This time-related phenomenon can lead to unexpected failures in plastic parts after days, months, or years in service. While creep rupture is more predictable and better understood under constant stress loading, creep rupture resulting from a constant strain condition is frequently encountered in several applications and is more complex to interpret. This complexity is due to the competing mechanisms of plastic creep and stress relaxation. This paper will provide insight into several long-term material behaviors in polymeric materials, with an emphasis on a scenario involving creep rupture as a result of constant strain over time.
Minimization of Part Warpage in Injection Molding through Ideal Wall Thickness Distribution
In this study, a method to reduce the warpage of injection molded parts by optimizing the distribution of their wall thickness is proposed. The method is based on an optimization procedure consisting of mold flow analysis, a parameterization tool for geometry manipulation and an evolutionary optimization algorithm. Starting with the initial design for the mold cavity, the procedure modifies the wall thickness distribution at user-defined area-sections. The result is an STL-file of the optimized design. Application on a warpage demonstrator reveals the effectiveness and plausibility of the proposed optimization procedure.
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