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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Ultrasonic Upsetting ? A New Method of Ultrasonic Staking to Join Hybrid Material Combinations
Mixed material joints become more and more important with reference to functional integration as well as weight and cost optimization. Furthermore, the requirements regarding the strength and the surface quality of the joint are also currently increasing. Concerning both criteria, heat staking processes provide the best results. But especially in contrast to ultrasonic staking, heat staking needs long cycle times to create the joint. The present article aims to define a suitable process strategy of ultrasonic staking, named ultrasonic upsetting, combining a high joint-strength with short process times. Additionally, other disadvantages of the conventional ultrasonic staking (e.g. contact of the horn with the mating part, staking of materials with low viscosity) are solved with this process solution.
Optimize the Mechanical Properties of Blow Molded Thermotropic Liquid Crystalline Polymers for Hydrogen Storage Applications
Thermotropic liquid crystalline polymers (TLCPs) are attractive candidates for manufacturing hydrogen fuel storage vessels because of the combination of their outstanding mechanical, barrier, and thermal properties. This paper represents the successful extrusion blow molding of TLCP materials. Significant improvement in the mechanical properties in the machine or hoop direction is observed if a higher amount of strain is applied in that direction. To stretch the parisons biaxially, a new mold with twice the cavity diameter and a parison stretching device have been designed and manufactured.
Effect of Miniaturisation and Process Induced Crystallisation on Mechanical Properties of Microinjection Mouldings
Miniaturized parts weighing few and tens of milligrams represent a large category of microinjection moulded products. Both miniaturization and extreme processing under microinjection moulding make material experience high shear rates and high cooling rates, and have differing morphology and final properties from conventional injection moulding. This paper studied the variation of cavity thickness (from 500æm to 100æm) and process (injection velocity and mould temperature) on morphology and short-term/long-term mechanical properties of miniaturised dumbbell specimens. It was found that oriented skin layer determined molecular orientation and broadly influenced Young?s modulus, elongation and yield stress. It accounted for over 60% of the cross-section when part thickness was below 200æm. Mechanical properties measured from the standard 4mm thick specimen cannot represent the properties manufactured under microinjection mouldings.
Effect of Retort on the Peel Strength of Rigid Plastic Containers
The effect of retorting on the peel strength of Polypropylene (PP) lids sealed to cups was studied. The peel strength increased as the sealing temperature and time increased. However, the peel strength decreased as the samples were retorted or autoclaved at 121øC for 60 minutes. Sealing and the subsequent cooling processes result in an interface that is in a metastable state. During retort the molecules at the interface could rearrange themselves into a more stable state, which could decrease the molecular interaction at the interface. This would decrease the peel strength after retort as seen in this research.
PVC Property Modification Using Styrenics Based Modifier Systems
PVC demand is likely to keep increasing over the next years. It?s competitive price, chemical resistance and processability has resulted in it being used for a wide variety of applications. With the addition of impact and heat distortion modifiers among others, it has become a very popular material for many industries. This paper discusses advancements in the areas of property modification based on styrenics to meet demanding customer requirements across a wide range of PVC applications.
Styrolution as the Nr. 1 styrenics supplier intends to futher contribute to the area of PVC modification through material innovation and technologies.
Computed Tomography X-Ray Imaging - A Novel Technique for Non-Destructive Examination of Plastic Products
The use of traditional X-ray imaging, one in which a 2 dimensional radiograph x-ray image is obtained has had limited use in examination of plastic products. The advance of digital, computing, and processing technology has lead to development of laboratory scale Computed Tomography (CT) X-ray imaging equipment for the use of non-destructive examination plastic products. CT is the process of imaging an object in all directions using X-rays and reconstructing image data to produce a duplicate, three-dimensional digital model of the scanned object. The internal and external structure of the object can then be viewed at any cross-section, point, or angle. CT allows the documentation and memorialization of an object, in its entirety, without destructive analysis and allows movement through the object to view areas of interest.
This feature of CT X-ray imaging makes it a valuable tool for use in plastic product failure analysis. The locations of cracks, voids, and presence of contaminants can be determined very precisely. This paper discusses this technology and its uses in performing plastic product failure analysis.
Basic Study of Thermosetting Injection Composites
Injection molding of thermosetting resin needs more delicate know-how than injection molding of thermoplastic resin. This becomes one of the entry barriers to thermosetting resin industry.
In this research, as a basic research of the thermosetting resin injection molding, IZOD impact test, bending test and tensile test were carried out to clarify the mechanical properties and analyze molding results of Glass Fiber Reinforced Thermosetting Plastics (GFRTP) which assumed phenolic resin as a matrix.
As a result, tensile, bending and IZOD impact properties of GF (Glass Fiber)/PF (Phenolic Formaldehyde) composites were higher than only PF.
In tensile test, the dumbbell specimens of GF / PF composites often broke in the dumbbell bottom. By SEM photographs observation, fiber in the skin side orients it at an angle of 0øfor the resin flowed direction and fiber in the core side orients it at an angle of 90øfor the resin flowed direction. And the specimens which broke in the dumbbell bottom have many ratios of the core side.
In bending test, by SEM photographs observation, fiber orients it at an angle of 0øand 90øfor the facture surface regardless of the skin side, the core side. Fiber orientation angle is unevenness.
It is thought that the difference in hardening speed of the skin and core side, an injection port position and many factors including the resin convection are related to these differences of fiber orientation and occur.
The technique to control these conditions is an important factor to mold thermosetting resin composites.
Effects of Wood and Cellulose Flours on Crystallization Behaviors of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)
This paper investigates the effects of natural flours on the crystallization behavior of poly(3-hydroxy-butyrate-co-3-hydroxyhexanoate) (PHBH). Two types of PHBH (3-hydroxyhexanoate (3HH) contents of 5.6 and 11.1 mol%) were used as a polymer matrix, and two types of natural flours (wood and cellulose) of 1 wt% were added to the PHBHs in order to improve the crystallization rate of the PHBH. Crystallization behaviours under non-isothermal and isothermal conditions were characterized using differential scanning calorimetery (DSC). Also, isothermal crystallization kinetics were analyzed using the Avrami model. The results suggested that both wood and cellulose flours enhanced the crystallization of PHBH with 3HH contents of 5.6 mol%. However, wood flours were found to have greater effects.
Experiments with Hot Tool Joining of Thermoplastics to Perforated Mild Steel
Lightening of structures to improve fuel efficiency of automobiles requires joining of dissimilar materials like metals to plastics. In this work, four thermoplastics, HDPE, polypropylene, acrylic and polycarbonate, were joined to mild steel sheets in a lap shear configuration using a heated tool. The steel sheets were perforated with a fine hole pattern and heated for a preset time by pressing it against a hot tool that was kept at a high temperature. Then the steel sheet and the hot tool were retracted, and the cool thermoplastic sheet was pressed against the hot metal surface for a preset time. The hot metal would then melt the thermoplastic surface resulting in flow of thermoplastic into the holes as well as wetting of the steel surface resulting in joining of the parts. For all the thermoplastics increasing the heating time increased the joint strength until an optimum was reached. Increasing the open area in the perforated steel generally resulted in the stronger joints. The strongest average lap shear strength was 4.6 MPa for HDPE, 6.7 MPa for polypropylene, 8.3 MPa for acrylic and 7.3 MPa for polycarbonate.
Understanding Spiral Mandrel Dies: Layering Effect and Gauge Uniformity
In this paper, the effect of the number of spiral overlap on the gauge uniformity of a blown film die was investigated. A typical center-fed spiral mandrel die and a special feed block were used for the tests. Every other spiral was fed with black and white master batches respectively. The layering effect was examined by monitoring the cross section of the thick sample at the outlet of the die. The film was also produced at two different thicknesses and the gauge uniformity along the circumference of the die was checked. The results showed that with increasing the number of overlap, gauge uniformity was improved. For better understanding the complex flow in spiral mandrel die, the flow on the die was also analyzed using a commercial available software package.
Force Controlled Friction Riveting of Glass Fiber Reinforced Polyamide 6 and Aluminum Alloy 6056 Hybrid Joints
The use of metal-composite hybrid structures is an efficient solution to reduce weight and fuel consumption in the transportation industry. Some conventional joining techniques for hybrid structures, such as traditional mechanical fastening and adhesive bonding are being used but have shown limitations. The present work intends to demonstrate the feasibility of the FricRiveting process to aluminum alloy 6056-T6 and glass reinforced polyamide 6 as well as to investigate the influence of the process parameter Forging Force on the joint formation (changes in the depth and width of the metallic rivet anchoring zone) and tensile strength. For that a new joining equipment and approach were used. The process was divided in three controlled steps: the first step was controlled by spindle displacement; the second step was controlled by rotational speed while the third step was time-controlled. The correlation between the rivet deformation (volumetric ratio) and the tensile strength was studied, as well as presumptive physical-chemical changes in the polymer (thermo-mechanical degradation) due to the high temperatures achieved in the process. The maximum average ultimate tensile strength for the selected conditions was 5041ñ 170 N (95% ñ 3% of the ultimate tensile force of the metallic rivet) and the polymer did not show any significant level of thermo-mechanical degradation.
Studies on the Blending of Abs/Pla for Creation of a New Green Engineering Polymer
Studies on the development of high performing ABS/PLA polymer blends have been done. The mechanisms of individual polymers have been investigated, showing the crystallization of PLA can highly influence its toughness. This can be controlled through process engineering during the molding of the polymer. In addition, ABS has been shown to undergo a crosslinking reaction during the timeframe of melt processing. Understanding these mechanisms has been crucial in the development of high performing ABS/PLA blends that have similar properties to the original ABS. These blends and their properties are discussed.
The Testing Program at NIST on Fibers Used in Soft Body Armor Applications
A first responder?s soft body armor failed to stop a threat for which it had been designed. Subsequent work at the National Institute of Standards and Technology (NIST) through the development of a suite of tests pointed to a possible synergistic combination of hydrolytic degradation and mechanical degradation due to folding on the fiber that comprised the soft body armor. The goal of this paper and presentation is to give an update of the research effort to date being conducted at NIST on polymeric fibers used in soft body armor with a special emphasis on new fibers under consideration. The overview covers mechanical fiber testing, microscopy, and spectroscopic techniques used to understand potential mechanisms of degradation in these materials. An update of our high strain rate effort will also be given.
Linear Vibration Welding under Industrial Conditions
Due to the increasing demands for weight reduction and integration of function, especially in the automotive field, components made of metallic materials are increasingly being substituted by components made of thermoplastic materials. In contrast to this, despite the high process understanding of vibration welding and the knowledge of the process-structure-property relationships, with theoretically achievable weld strengths of 90 % to 100 % of the unreinforced base material strength are far higher than can achieved in industrial series production. The complexity of an industrially manufactured component is simulated by using plate test specimens. The results of the welding experiments show that different wall thicknesses in the weld area, component warpage and different friction angle within the weld leads to nonuniform local process conditions during linear vibration welding process. This results in local weak spots, which reduce the total component strength. These local weak spots can be reduced by using alternative process strategies, such as in-process pressure variation and IR preheating. So not only the local strengths but also the total component strength can be increased. This is shown with the example of component warpage.
Effect of Added Plasticizer on Moisture Diffusion through Polylactic Acid/Clay Nanocomposites
Polylactic acid (PLA), a bio-derived, biodegradable polymer, is being used as a substitute for conventional, non-biodegradable polymers in packaging applications. However, it has poor barrier properties for gases and water vapor, and these can be improved by dispersing nanoclay platelets in the polymer. In this work, the effects of adding nanoclay and a plasticizer, namely acetyl tributyl citrate (ATBC), on the water vapor permeability of PLA films have been evaluated; a variety of mixing methods were employed. It was found that while nanoclay addition can help in lowering the permeability through both the plasticized and unplasticized PLA, the effect was less than anticipated in the presence of the plasticizer. However, if the nanoclay dispersion was assisted by ultrasonication, the results in the two cases were comparable. In addition, it was found that the method of mixing during nanocomposite preparation also had significant effect on the permeability properties of the plasticized samples.
Coextrusion Processing of Multilayered Dielectric Polymeric Films
Current state-of-the-art biaxially oriented polypropylene (BOPP) film capacitors occupy large volume fraction in many electronics applications such as pulsed power and power conditioning technologies. Other disadvantages of BOPP films include increased losses, reduced energy density and lower breakdown strength at high temperature. Development of multilayered polymeric films with higher energy density and high temperature performance is, therefore, necessary in a wide range of applications. As demonstrated in this work, coextruded films of poly(vinylidene fluoride) (PVDF) and polycarbonate (PC) have been successfully developed for the use up to 140 øC. For further dielectric properties improvement, interfacial properties of the PC and PVDF layers were manipulated using a tie layer. Poly(methyl methacrylate) (PMMA) was used as tie layer to investigate its impact on the dielectric performance of PC/PVDF films. In previous work, PMMA was successfully used to improve the breakdown strength of the multilayered films of PVDF-copolymer and PC. This paper will demonstrate development of multilayered capacitor films and effect of PMMA tie layer on dielectric properties for high temperature applications using coextrusion technology.
Study the Effect of hBN Fibre Content and Aspect Ratio on PLA Based Composite Thermal Conductivity
As electronic devices become smaller and more powerful, heat concentration and as a result heat dissipation would highly affect their efficiency. Also with rising awareness about environmental protection, using bio-based (green) materials as electronic packaging is more important than before. In this context in this research liquid crystal polymer (LCP), hexagonal boron nitride (hBN) high thermally conductive composite fibers were produced and effects of LCP-hBN fiber content and aspect ratio in composite with Poly-lactic acid (PLA) on effective thermal conductivity of the composite were studied. Based on previous studies the largest thermal barrier effect against increasing thermal conductivity of composite is filler particles percolation and phonon scattering at filler particles boundaries. In this study it is observed that the same thermal conductivity as pure fiber can be achieved in composite with lower fiber loading, as long as suitable fibers interaction exist at optimized fibers aspect ratio. This suggest that at right filler content and aspect ratio it is possible to eliminate filler percolation thermal barrier effect and transfer all of the received phonons through the composite thermal pathways rather than scattering them.
Low-Permeation Toughened Polyoxymethylene (Pom) for Injection-Molded and Blow-Molded Tanks in Small Off-Road Engine (Sore) Applications
Polyoxymethylene (POM) polymers exhibit excellent chemical resistance against various chemical substances, such as hydrocarbons. However, due to POM?s relatively low impact strength, its use in containment of chemicals, such as chemical bottles and tanks, has been limited. The development of both injection-moldable and blow moldable low-permeable, toughened POM will be discussed. Impact-modified POM, using a coupling technology, has been molded into gasoline tanks for small off-road engine (SORE) applications. The tanks passed the impact requirement, while maintaining the fuel permeation performance below the regulation limits by US Environmental Protection Agency (EPA) and California Air Resources Board (CARB).
A Study of PEEK/hBN Composites as a Commercial Material Option
This study analyzes the bulk material properties of a PEEK/BN composite and provides a comparison to the commercial PEEK resins including unfilled, carbon fiber filled, and glass fiber filled materials. It was found that the BN filled PEEK had a similar storage modulus, measuring lower than the carbon fiber filled and higher than the glass fiber filled materials, at temperatures both above and below the glass transition temperature. The thermal conductivity of the BN filled PEEK was higher than all of the commercial grades when measured in the in-plane direction. The BN composites also possessed a similar toughness of the commercial grades, but the weld point of the BN filled matrix was more fragile than the commercial systems.
Isothermal Crystallization of Isotactic Polypropylenes: Experiments and Simulation
The isothermal crystallization of isotactic poly?propylenes (iPP) was investigated by polarization micro?scopy (PLM). The crystal radius evolution and the transformed volume fraction were obtained by PLM experiments. In this paper, a general differential system for 2D quiescent conditions was adopted to describe the crystallization evolution of iPP. Matlab was used for the simula?tion of the crystallization evolution. There was good agreement between the experimental and simulation results of the transformed volume fraction and the radii of crystals for the 2D condition.
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