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 fundamental study of the microcellular foamed structure in rotational molding was conducted by using polymer microspheres as a blowing agent. The influence of the viscosity, temperature dependence of viscosity and first normal difference of different resins on the cell morphology and the tensile properties of the foamed parts was investigated.
It is known industry wide that polypropylene (PP) resins plasticate in single-screw extruders at rates that are less than those for linear low density polyethylene (LLDPE) resins. The goal of this research is to show the magnitude of this rate reduction, and the physical properties related to processing that are causing the rate reduction.
The measurement of titanium dioxide color is one which has historically had a large degree of error associated with it, typically quantified as the measurement standard deviation error. The determination of this measurement error is typically obtained by performing the 6 Sigma designed experiment known as a Gage Repeatability and Reproducibility (GR& R) Study.
Shrinkage and warpage prediction of injection molded components relies on the calculation of residual stresses developed during the molding process. We present a method for increasing the accuracy of residual stress calculation. The method is applicable to amorphous and semi-crystalline materials and is effective for both filled and unfilled materials. Results obtained using the method on 3D geometry models will be presented and compared to experimental results.
From simple step experiments, it was observed that the rate at which heat is added to a polymer extrusion process through friction forces and the system heating elements is different to the rate of natural or forced cooling. This indicates that a single model that attempts to describe both heating and cooling is inadequate for control system design. A method for finding heating and cooling models using system identification techniques is demonstrated.
The material database CAMPUS is increasingly used as data supplier for structure simulations (FEA) in plastics product development departments. The calibration of material models with mechanical data of the database means a large expenditure, especially if different materials have to be compared. Thus, a concept is developed, which characterizes the material behavior in a large strain rate, strain and temperature range with a high automation degree. So the expenditure is considerably reduced and an improved plastics-oriented simulation is realized.
The use of color additives in the injection molding process is one of the most effective ways to add value to molded parts. Considerations must be made, however, on how additives are measured, handled, and processed, as well as attention paid to any cross-functional features the final part may require.This paper will examine basic design considerations for adding color at the press vs. using precolored resins in terms of final costs, handling, and processing.
The scanning particle monitor (SPM) provides in-line imaging of low concentrations of dispersed phases (e.g. particles, droplets, microgel) at different points across a translucent polymer melt flowing in an extruder. Quantitative measures of size, velocity, and concentration are currently being obtained in polyethylene-based systems. The monitor's ability to scan across a flow channel provides three-dimensional information on the dispersed phase properties. Customization of the system for manufacturing environments is in progress.
A first step towards fundamental optimization of extrusion processes is the determination of the effects of screw elements on flow and mixing. We present a measurement method to study local residence time distribution (RTD) inside a co-rotating twin screw extruder. Using a transfer function, we are able to characterize the effects of different types of elements on the local RTD with a 2-parameter fit. The new approach can be a major step towards determining the correct screw configuration from the desired mixing rate.
This paper describes past and recent innovations in extrusion technology. Issues related to implementation of innovation will be discussed with examples of successful as well as unsuccessful implementations. In the end, we will try to look into the future and speculate on possible new developments in extrusion and their effect on the plastics industry.
Driver and passenger safety continues to grow in importance in the automotive industry due to regulatory and market drivers. The increasing demands in airbag technology have challenged the material requirements to extreme levels.This paper describes the development of a new series of Thermoplastic Vulcanizates (TPVs), specially designed for airbag covers. The new materials have proven to be very competitive with other materials in this segment due to its reliable performance in a broad temperature range.
Supercritical Carbon Dioxide (SC CO2) is used as a reaction/processing medium in the fabrication of fiber reinforced composite materials. SC CO2 allows resin to wet out fiber reinforcement and penetrate inside the fibers themselves. This process produces a composite that exhibits ultra-long range order from the nano-scale to the macro-scale. This paper will discuss the fabrication technique in detail including process parameters and the structure of resulting composites and morphology of modified fibers.
Extruders are generally long pipes, which, although an excellent choice for many of its functions, is not ideal for mixing.With a rotor larger in diameter than the extruder to which it is attached our system can deliver excellent distributive and dispersive mixing and the use of mixing inserts allows process conditions to be easily changed.In particular the geometry allows for very high rates of cutting despite very short distances between inlet and outlet.
Crosslinked polyethylene is commonly used for hot water applications. The objective of this investigation is to find the optimal loading of an ethanol based silane coupling agent. This will be tested by performing a heated tensile test. This will indicate the polymers crosslink density and modulus. The goal is to find the optimal balance of crosslink density that will yield a pliable final material that can withstand the necessary temperature ranges for hot water applications.
Three types of specimens of a polyester-amide and a poly-hydroxybutyrate have been tensile and tensile-impact tested. These specimens represent different geometric characteristics; one specimen has a cold weld line. The influence of injection molding settings on tensile behavior was in agreement with tensile-impact results. Embrittlement was found for all specimen types and both materials after 20 months of storage. The beneficial effect of annealing on toughness was shown for poly-hydroxybutyrate specimens without weld line.
Several different methods are used throughout the industry to set up the injection phase of the injection molding process. This study is intended to look at the long-term robustness of several methods. Investigating the peak pressure and cycle integral consistency when regrind and check ring wear are introduced will do this.
An effective technique for characterizing long-chain branching (LCB) in polyethylene resins has been being developed. Triple detectors (concentration, RI or IR; viscosity, DP; and light scattering, LS) are added to the GPC system to render a powerful capability of studying polyolefin structures. As a result, low levels of LCB in HDPE can be clearly detected. In this work, three model HDPE resins were studied and the level of LCB is found to have a profound effect on the morphology formation in film blowing.
The purpose of the research was to discover the contributing factors of unexplained cavity cracking in a two-shot molding process. This project used Finite Element Analysis to study the effects of pressure and fatigue stress on the given cavity insert.
For compounding experiments, Surlyn types of ionomer extrusion materials were used. Comparison was made between two zinc types of ionomer copolymers with respect to the degree of exfoliation of clay nanofiller characterized by XRD and electron microscopy. Thermomechanical properties were characterized by the temperature dependence of complex modulus on DMA. Abrasion resistance was evaluated as well.
Raman spectroscopy of PMMA was obtained to find out the effect of dissolved CO2 on the phase change of the plastic. It has been demonstrated that the measuring method is useful to evaluate the amount of dissolved CO2 and to recognize the phase change in the polymer induced by the retrograde vitrification.
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Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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