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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Hygrothermal Effects on Physical Aging and Structural Recovery of an Epoxy Thermoset
We have investigated the hygrothermal effects on thin epoxy films (c.a. 60 µm thick) using mass uptake, swelling and uniaxial creep compliance measurements inside a dew formation-free transparent chamber capable of arbitrary relative humidity and temperature controls. We show that the physical aging behavior in humidity down-jumps in RH are the first demonstration of an asymmetry of approach induced by moisture changes in a material. Preliminary efforts to extend the TNM-KAHR models of structural recovery to account for moisture induced aging effects are presented.
Roll Design: A Review of the Basics
Over the years many advances have been made in the production of flat sheet in the areas of die design, screw design, and polymers. However the design of a critical part, the cooling roll, is often given little consideration by the processor. The intent of this paper is to review some of the parameters that the roll designer uses to determine the design of the roll. The basic equations for calculating PLI (pounds per linear inch), and deflection of the roll, the heat removal rate required, and a method for approximating the required flow rate through the roll are explained.
Thermosetting Resins from Vegetable Oils
A range of polyols and thermosetting polyurethanes was prepared from soybean, corn, sunflower, safflower, canola, peanut, olive and castor oils. The products were rigid plastics if the polyol hydroxyl number was 160 mgKOH/g or above, or rubbers when the OH number was below that value. Tg of the resins showed linear dependence with the hydroxyl number. The exception was castor oil, which was rubbery, although the OH number was 164 mgKOH/g, which was attributed to the presence of double bonds.
Does Color Memory Exist?
While the scientific literature contains information about how the brain stores and retrieves memory, there are no references in the recent literature about the ability to remember a color. Data collected over a several year period shows that this ability is rather poor, even after short periods of time. Only thirty percent of participants at plastics coloring seminars were able to correctly identify a color observed only an hour earlier.
Performance Optimization of Transparent PS Packaging with Clear Elastomers
Clear, high styrenic elastomers (HSE) are commonly extruder blended with general purpose polystyrene (GPPS) to make sheet, which is thermoformed into articles for packaging and single service applications. The ability to adjust the blend parameters gives the processor an advantage over other clear polymers in meeting customer cost and performance demands. Transparency and impact resistance of such blends are affected by the HSE and GPPS selection, and the blend ratio. This paper discusses the influence of these parameters, with emphasis on GPPS selection.
Influence of Molecular Weight and Polydispersity on Interfacial Tension between Polystyrene and Polyethylene
The influence of temperature, molecular weight and polydispersity on interfacial tension between polyethylene and polystyrene was studied in this work. The molecular weight of monodisperse samples of polystyrene was varied from 13,000 g/mol to 400,000 g/mol. The effect of polidispersity was studied using bimodal, trimodal and multimodal polystyrene samples prepared by solvent evaporation. It was shown that the interfacial tension increases as a function of molecular weight and decreases as a function of polydispersity.
Effects of Lubricants on Processing of Metallocene LLDPE
Fatty acid ester and amide lubricants were evaluated as processing aids in a 1.0 MI film grade mLLDPE. The effect of the lubricants on extruder energy and output of laboratory extruders fitted with a capillary rheology die and with a two inch film die were determined. Additives were found that reduced the amount of extruder energy required to process the mLLDPE. These additives also increased the output of the extruders per unit of extruder energy.
Thermogravimetry (TGA) of Polymers Poster
This poster describes Thermogravimetry (TGA) as a useful analytical tool for the plastics industry. Whether a TGA is used for compositional analysis of material, identification of filler in the material, a material's carbon black content, or moisture content, this poster will be valuable to engineers, scientists, and technicians.
Studies of the Thermal and Thermooxidative Degradation of Polypropylene during the Processing and Usage
Due to the extensive use of polypropylene, the comprehension of its stability and degradation processes is essential. In particular, our interest was to distinguish the differences between thermal and thermooxidative effects on its properties. The influence of temperature and atmospheric conditions on the time dependent aging process of PP was investigated. By means of suitable analyses, it has been proved that inert conditions can significantly reduce the degradation of polypropylene both in use and while processing.
Biaxial Vibration Welding of Polypropylene
Vibration welding machines with biaxial amplitudes were designed to close the gap between traditional linear friction movement and ultrasonic welding. Several advantages are claimed, although no scientific results on this innovative joining technology have been published so far. In this work, linear/biaxial vibration welding experiments have been made on sensor-equipped machines. A considerable influence of amplitude on temperature in the welding zone and of joining pressure on short-time mechanical joint strength exists for polypropylene plates.
Investigation of a Thin-Walled Thermoplastic Metal Hybrid
Based on the researched material combinations, warpage of a T-formed thermoplastic metal composite with a large contact area depends mainly on the shrinkage of the thermoplastic and on the pre-heating temperature of metal parts. The bearing strength increases linearly with the number of the rivet holes and depends on their geometries and the pre-heating temperature. The adhesion between the zinc-plated steel and PA6-GF30 at the pre-heating temperature of 250°C is greater than the tensile resistance of the thermoplastic part.
Progressive Failure Analysis of Fiber Composite Structures
A progressive failure analysis of fiber reinforced composite laminates using finite element analysis is presented. The progressive failure model is based on the Hashin-Rotem failure criterion, which separates fiber and matrix failure modes. In the analysis, the lamina material properties are reduced depending on the failure mode until ultimate failure of the laminate is reached. The progressive failure analysis is compared to published tensile experiments on various carbon/epoxy laminated structures with good agreement.
Rheological Properties and Numerical Simulation of S-PVC Formulations in Extrusion Dies
We report effects of formulation and sample preparations on measured rheological properties relevant for constitutive modelling of die flow in PVC extrusion. Numerical simulations are performed in order to separate non-isothermal and viscoelastic effects in the extrusion experiments as well as self-consistency between constitutive models and measurements.
Design of a Novel Extrusion System for Manufacturing Microcellular Polymer
The described system for the production of microcellular hollow fiber is based on the thermic extrusion of polymers under addition of CO2 as a blowing agent by means of pressure build-up and drop-off. The design of a novel extrusion system is presented according to this concept, which involves a modular configured co-rotating twin screw extruder, a gear melt pump and a designed die. Microcellular foams have been successfully produced using this system.
Melt Extruded Open-Cell Microcellular Foams for Membrane Separation: Processing and Cell Morphology Relationship
This paper presents an experimental study on the manufacture of microcellular polycarbonate in a designed twin-screw extrusion system using CO2 as blowing agent. Open-cell microcellular polycarbonate foams in the form of hollow fiber were produced with a cell density on the order of 109-1010 cell/cm3 and an average cell size in the range of 5-10 µm. The effects of the processing conditions on the cell morphology and the cell-opening technique are described.
Superior Customer Service: A Competitive Advantage
In this period of increased competition and expected quality superior customer service remains an area for differentiation and competitive advantage. Technology has offered customer service enabling tools but does not ensure superior customer service. This paper will discuss what is superior customer service" today and in the future and how your company can gain a competitive advantage through its customer service."
Importance of Injection Molding Parameters for Mechanical Performance of Cold Flow Weld Lines
Tensile and tensile-impact test results are reported on specimens with a cold weld line and identical specimens without weld line. Pairs of specimens without and with weld line have been injection molded simultaneously. Test results indicate that the effect of flow-induced stresses on weld line strength should be taken into account, in addition to the well-known influence of material temperatures during molding.
A Unified Approach for Thermoforming Numerical Simulation
In this paper, we present a unified approach for numerical simulation of thermoforming process. In contrast with iterative methods and dynamic explicit scheme, we propose a high order explicit algorithm based on the classical 4th order Runge-Kutta scheme. The proposed procedure is used to solve the global equilibrium equations and to integrate the sheet viscoelastic constitutive model. The error and time step size control is performed at each level which increase the procedure robustness and efficiency.
Feasibility of the Use of Polystyrene/Polypropylene Blends
The purpose of this investigation is to study the feasibility of PS/PP blends. The analysis of the results shows that compatibilization of the blend with one kind of SBS copolymer improves some mechanical properties of the blend. However, the amount of copolymer to be added depends on the intended specific uses. The cost/profit relation must always be observed.
Study of Staggered Flow Fronts with Applications to Sensor-Based Control
The present study examines several issues of relevance in the understanding and development of techniques for characterizing and controlling flow fronts developed in the VARTM (Vacuum Assisted Resin Transfer Molding) process. A sensor-based control system was used to selectively and autonomously compensate for lagging flow fronts resulting from permeability variations in the constituent preform. The fundamental control objective was to thoroughly impregnate the entire fibrous preform in a minimum amount of time, subject to minimizing the flow lag" induced by dissimilar preform peremeabilities."
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