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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A method for rapidly characterizing the shape, size and distribution of bubbles in foam has been developed. The method is based on the extraction of bubble shapes from high resolution images of microscopy slices of the foam, using image segmentation. The foam studied is the 30 mm thick high impact polystyrene coating of a thermally insulated pipe. The coating is applied using extrusion with a chemical foaming agent and the image segmentation provides a dataset with the ellipse fit of 500.000 bubbles.
The paper presents a theoretical and, at the same time, an experimental approach to sheet bending with pads made of rubberlike materials. Numerical simulation for V bending was carried out by using the ABAQUS/Standard software package. The program takes into account the following: sheet material, pad material, punch stroke and punch radius. The theoretical results are compared with experiments in order to determine whether the numerical simulation is close to reality and whether it gives correct information about the process even in the area that can’t be reached by experiments. Some statistical tests were performed in order to validate the results. Moreover, a proposal for replacing rubber with plasticized PVC using two different recipes was made.
The American phrase ‘garbage in, garbage out’ (GIGO for short) succinctly describes a problem often faced by plastics extrusion processors worldwide: No matter how well an extruder extrudes, its output will not be on-spec if the input blend is off-spec. When formulation problems do arise, the on-line proportioning system draws initial troubleshooting focus. But the problem itself (or its underlying cause) may lie elsewhere, farther upstream. This presentation systematically addresses the major process operations prior to extrusion (and beyond to include the materials themselves) in an effort to indentify and avoid the various pitfalls that may plague reliably accurate formulation.
3-dimensional FEM simulation was performed to clarify the mechanism on surface replication in micro-injection molding and thermal nanoimprinting. Especially the filling behavior into micro- and nano-surface features was discussed in comparison with the experimental results. The simulation results and the experimental results of injection molding show possibility of the generation of air traps in the filling stage and it is considered that those air traps have a strong relation with replication shape and replication rate. The simulation results of thermal imprinting clarified penetration behavior of polymer melt into nanosurface feature and show that the aspect ratio of the cavity and imprinting pressure influenced flow behavior in thermal imprinting.
Cyclic butylene terephthalate (CBT) is a novel thermoplastic matrix material for composites. Besides its low viscosity (0,02 Pas) and superior mechanical properties CBT has some other advantages over conventional matrix materials. During its polymerization no by-product is being made and it is easy to recycle. But processing of CBT is complicated and may results in a brittle material. Polycaprolactone (PCL) as an additive for CBT will also be introduced to increase toughness. In this paper the proper amount of PCL is determined to obtain a ductile material and a method is described how to fabricate prepregs and composites.
In this study, the effect of various misalignments of the circular notched bar (CNB) specimens on the fatigue crack propagation behavior of pipe grade polyethylene is investigated by three dimensional numerical analyses. The effect of the asymmetric crack growth of the misaligned CNB specimens on the lifetime to failure is also addressed. Two types of misalignments of the CNB specimen, i.e., (a) a concentric misalignments (Case I) and (b) an angular misalignments (Case II), are considered using finite element analysis. It is observed that as the misalignments increase, the asymmetric crack growth is accelerated so that the time to reach the critical SIF decreases. Therefore, it can be understood that the lifetime to failure of CNB specimens can vary noticeably once the CNB specimen is misaligned initially. Considering results from this study, the fatigue crack growth behavior including the estimation of the lifetime of CNB specimens should addressed by considering the misalignment effects.
The present work attempts to implement reactive compatibilisation of blends of recycled engineering plastics, more particularly the case of recycled PA66 contaminated by recycled PA6. Low molecular weight, high Tg Styrene-Maleic Anhydride copolymers were tested as chain extenders / compatibilizers. It appeared that the addition of 2% by weight of SMA to an incompatible system of recycled PA6 and PA66 improved both ductility and impact performance by factors of at least 10 and 1.5 respectively. Moreover, high Tg SMA improved performances at elevated temperature, partly due to its ability to effectively crosslink but also because of its inherent heat resistance.
New Ultramid® Endure from BASF is the first of its kind PA66 based polymer which has excellent heat ageing resistance,welding strength after heat ageing and good processing properties. Ultramid® Endure can withstand continuous use over 3000 hours at 220°C and temperature peaks upto 240°C. The excellent heat ageing properties of Ultramid® Endure allows it to be used for applications such as resonator, charge air lines etc.
Poly(o-aminophenol) (POAP) films were deactivated and then reactivated, and dependences of the different charge-transport and charge-transfer parameters on the degree of deactivation (c) were obtained by employing Electrochemical Impedance Spectroscopy. These dependences were extracted when the polymer contacts an electroactive solution and a mediation reaction occurs at the polymerelectrolyte interface. While some parameters, such as interfacial metal-film and film-solution resistances (Rmf, Refs, Rifs), the high-frequency capacitance (CH) and the redox capacitance (Cp) exhibit a continuous variation without hysteresis between deactivation and reactivation processes within the whole c range, others, such as electron and ion diffusion coefficients (De, Di), show hysteresis between consecutive deactivation and reactivation processes. On the basis of these findings it was considered that while some parameters of the polymer only depend on the amount of redox active sites, others (De and Di) depend on both the quantity and distribution of redox active sites.
With the progression of technology, increasing pressure is put on engineering plastics companies to fulfill strict design criteria of equipment manufacturers. Therefore novel materials are needed to address specific needs. The most common method to manipulate material performance is by either blending or an additive approach. Although relatively cost-effective and requiring low technological input, these methods are not always desired due to the potential incompatibility of blends and/or nonpermanence of additives. In this paper a copolycarbonate approach will be discussed to address specific consumer needs. More specifically the tailoring of properties from a molecular perspective will be discussed and examples showed of how copolycarbonates can be used to capture novel markets.
Multi-walled carbon nanotube/high density polyethylene composites with varying amounts of carbon nanotubes were processed in an extruder fitted with a low-shear adaptor. This equipment allowed annealing of the melt for various amounts of time under low shear before it was passed through a slit die. The effect this treatment had on the electrical and mechanical properties of the composites was investigated. Results obtained from extruded samples were compared to the mechanical and electrical properties of samples that had been mixed in a micro-compounder and compression molded. Differences in the crystallinity and the orientation of extruded samples were also assessed.
A number of water utilities in various states of USA have reported a persistent premature failure of polybutylene (PB) tubing in water distribution system. Failure analysis of PB system and a methodology of reliability analysis of PB tubing in potable water application are presented in this paper. The reliability analysis allows predicting future failures. Thus, the proposed methodology is validated by comparison of failure prediction with actually reported field failures in selected water districts from Maryland, Georgia and Ohio. The proposed methodology also allows a rational replacement planning by considering the effect of preventive replacement program on the reduction of emergence replacements. Understanding of main PB failure mechanisms in potable water application important for proper interpretation statistics is also discussed.
A new method of evaluating the polyethylene (PE) pipe lifetime in brittle failure has been recently proposed. It consists of an extrapolation of the failure time in the Pennsylvania notch test to arbitrary PE pipes at various loads and temperatures. This paper presents a detailed review of the theoretical and experimental basis of the new lifetime prediction method and discusses its limitations. An experimental examination of the proposed method applied to a commercial high-density PE is reported. The results suggest that the proposed method overestimate the lifetime at room temperature by 30 ~ 40 times. It is inadequate for extrapolation of brittle fracture time of PE from 80°C to room temperature. Such limitation is related to the changes in failure mechanism and kinetics of crack growth taking place at some intermediate temperature. An alternative method for PE pipes lifetime prediction based on a combination of testing and modeling is discussed.
There are three major modes of polyolefin pipes failure: ductile, stress driven brittle and degradation assisted brittle fractures. The ductile failure results from material instability on macro-scale. It appears as a ballooning resulting from large-scale strain localization (stretching and thinning) similar to that observed in cold drawing in uniaxial tension (necking). The brittle fracture is manifested in cracking with no large deformation on macro-scale. However, there is a localized crazing in front of the crack, which consists of micro fibers and membranes. It also results from cold drawing, but on micro-scale. This paper presents analysis of cold drawing as time dependent phase transition referred to as “delayed necking”. The connections between ductile and brittle polyolefin pipes failure from one side and delayed necking on another are discussed.
The effect of talcs on PolyLactic Acid (PLA) performance has been studied with a focus on properties of fully crystallized PLA. The results show that talc could be used as an effective nucleation agent to improve mechanical properties of PLA including stiffness, heat deflection temperature and impact strength. It is also shown in two PLA formulations that Luzenac High Aspect Ratio talc (HAR®) in combination with plasticizers and impact modifiers could further improve crystallization speed and impact properties through modifying the amorphous phase of PolyLactic Acid.
This paper presents a new method to determine residual stress profiles in cables and other axisymmetric objects using digital image correlation and inverse modeling. 3D digital image correlation with two cameras and stereo-vision was used to determine full-field displacements resulting from cutting a slit in a disk made from cable insulation. These displacements were compared to predicted displacements in a finite element analysis of the cutting. Differences between nodal displacements and the corresponding measured displacements were used to construct a cost function which was iteratively minimized by changing the residual stress field used as initial condition in the finite element simulation.
Cyclic olefin copolymers (COC/TOPAS) are commonly employed for making microfluidic devices. Several issues need to be addressed before this can be realized. A reliable technique for micro-replicating COC is required. Good sealing and high bond strength between COC inter-layers without destroying channel integrity is necessary. The intrinsically hydrophobic surface has to be rendered hydrophilic to facilitate flow and electrophoretic separation. Here we report the production of high fidelity microdevices by hot-embossing. Thermal seals with high bond strengths for bonding below the glass transition temperature Tg, photografting using suitable hydrophilic monomers to give good surface wettability and hemocompatibility are outlined.
Design of experiments (DOE) is a systematic method based on designed experimental rums used to evaluate the effects of selected variables on the final product properties. The method is especially useful when materials are expensive and/or scarce and only small quantities are available for experimentation, such as with carbon nanotubes (CNT). The effects of injection molding on the properties of Polycarbonate and Polybutylene Terephthalate multi-wall CNT composites were studied using DOE. Results demonstrated that although only a small number of experimental runs were used, a significant effect of the injection molding parameters on the properties of the nanocomposites was detected.
The physicochemical properties of plasma polymerized films were investigated by means of X-Ray photoelectron spectroscopy (XPS), Fourier Transform infrared spectrophotometry (FTIR), ellipsometry and Water Contact Angle. Three different monomers (acrylic acid, ε-caprolactone and lactic acid) were polymerized in a Plasma Polymerization System for different times (7, 15 and 30 min) and power conditions (80 and 120 W). While plasma polymerized acrylic acid and ε-caprolactone shared a strong similarity with the conventional polymers, lactic acid did not bear any resemblance to the conventional polymer.
The papers from the most recent IOM3 conference, PVC 2011, are used as the basis for this paper. The PVC market is reviewed on the basis of Europe’s environmental challenges with management options being reshaped by global megatrends. The cost competitiveness of PVC products, energy saving from using PVC products and increasing recognition of our sustainable development progress can only serve our industry well into the future. The Voluntary Commitments of the past ten years (Vinyl 2010) and the next ten years (VinylPlus) are reviewed. Examples of educational initiatives in the UK to improve perceptions are also highlighted.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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