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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Influence of Surface Energy on Dispersion and Flexural Properties of PS/Phosphonium Organoclay Nanocomposites
Phosphonium-modified montmorillonite (PMM) organoclays were used to produce polystyrene (PS)/clay nanocomposites by melt processing. Two PS resins with different molecular weights were used, along with four different PMM organoclays. The structure of the resulting nanocomposites was characterized using wide angle X-ray and transmission electron microscopy. It was found that the quality of clay dispersion, nanocomposite thermal stability, and flexural mechanical properties depend on the combination of organoclay type and PS molecular weight. The differences are discussed in light of the interfacial tension values measured for the different PS/PMM systems.
Fast Acquisition Melt Pressure Measurements to Detect Flow Instabilities. A New Option for Capillary Rheometers
Flow instabilities cause various problems in extrusion blow- or flat film processes. Especially shark skin is affected by the molecular structure. This phenomenon is analyzed in various scientific works using apparatus that are complex or difficult in operation.A new set-up, now available is being presented as an option for new and existing capillary rheometers, consisting of a special designed die and a fast responsive transducers system. The software allows the evaluation of diverse pressure frequency regimes causing flow instabilities. Measurement examples are given for different shear rates and polymers. The measured frequency regimes are related to molecular parameters.
Casting of Zein Protein Polymers
This paper reviews an investigation of the processability and properties of commercially available corn protein polymers for cast film products. Different formulations of protein substrates were cast and characterized for their mechanical properties. In this study it was seen that zein plastic sheets could be cast with tensile strengths as high as 6 MPa with a strain to failure of 6%. In addition, ultrasonic treatment of the solution, prior to casting, reduced the tensile strengths; however, the treatment did enhance the strain to failure to as high as 200%. Lastly, the addition of nanoclays also reduced the tensile strength of the cast films.
Preparation of Gold Nanoparticles Filled Poly Dimethyl Siloxane Membrane for Gas Separations and its Reverse Selective Phenomena
A novel nanocomposite membrane, poly dimethyl siloxane (PDMS)/Au was prepared for carbon dioxide/methane separation. Synthesis of stabilized nano particles is also reported. The nanoparticles were characterized by UV-visible spectroscopy and transmission electron microscopy (TEM). The hybrid membrane was characterized morphologically by scanning electron microscope (SEM) and the change in inter-segmental distance due to filler loading by wide angle X-ray diffraction patterns (WAXD). The gas transport properties were measured at different pressures and temperatures. The effects of filler loading on permselectivity, diffusivity selectivity and solubility selectivity are reported for CO2/CH4 separation. Reverse selective phenomena of PDMS/Au nanocomposite membrane over the conventional PDMS membrane is explained based on sorption kinetics of CO2.
Viscoelastic Flow in Micro-Injection Molding
Understanding the free surface flow of viscoelastic fluids in micro-channels is important for the design and optimization of micro-injection molding processes. In this paper, flow visualization of a non-Newtonian polyacrylamide (PA) aqueous solution in a transparent polymethylmethacrylate (PMMA) channel with microfeatures was carried out to study the flow dynamics in micro-injection molding. The transient flow near the flow front and vortex formation in microfeatures were observed. Simulations based on the control volume finite element method (CVFEM) and the volume of fluid (VOF) technique were carried out to investigate the velocity field, pressure, and shear stress distributions. The mesoscopic CONNFFESSIT (Calculation of Non-Newtonian Flow: Finite Elements and Stochastic Simulation Technique) method was also used to calculate the normal stress difference, the orientation of the polymer molecules and the vortex formation at steady state.
Novel PET Nanocomposites with Enhanced Barrier Performance of Interest in Food Packaging Applications
PET is one of the polymers most widely used in the packaging industry. However, it is highly desirable to enhance its barrier properties for applications such as carbonated drinks and for other rigid and flexible packaging applications. The nanocomposites route offers unique possibilities to enhance the properties of this material, provided that adequate thermally resistant and legislation complying nanofillers are used. This paper presents novel nanocomposites of PET with enhanced barrier properties to oxygen, water and d-limonene based on a new specifically developed food contact complying montmorillonite grade. Morphology and thermal properties are also discussed as a function of filler content.
An Examination of the Relative Impact of Common Potable Water Disinfectants (Chlorine, Chloramines and Chlorine Dioxide) on Plastic Piping System Components
The three most common disinfectants in potable water are chlorine, chloramines and chlorine dioxide. While these disinfectants are all oxidants, their unique characteristics can result in a significantly different impact on the performance of plumbing system components. In this paper, the chemistry and characteristics of the oxidants are discussed in the context of oxidative degradation of plastic piping system components. Testing strategies to ensure material performance in potable water applicationsare presented and reviewed.
Effect of E-Beam Sterilization on the Physical and Optical Properties of Medical Plastics
Electron beam (E-beam) exposure is becoming increasingly popular as a lower cost alternative for the sterilization of medical devices and rigid medical packaging. The objective of this study was to determine the effect of E-beam sterilization on several plastics typically used in medical devices and packaging including: copolyesters, polycarbonate, acrylic and cellulosic polymers. Exposures of 25 and 50 kGy (2.5 to 5.0 Mrad) were found to induce significant yellowing. However, color measurements performed at various intervals subsequent to the exposures indicated that the yellowing decreased over time, each plastic to a different degree. Effects of these E-beam exposures on physical properties of these plastics were also determined.
Process Optimization of Injection Molding by Integrating Numerical Simulation with Surrogate Modeling Approaches
An integrated optimization system that can adaptively and intelligently determine the optimal process conditions for injection molding has been developed. Nonlinear statistical regression techniques and design of computer experiments are used to establish adaptive surrogate models that can substitute time-consuming numerical simulation and quickly provide predictions with adequate accuracy for system-level optimization. While the Gaussian process (GP) surrogate model is being refined, a multi-objective genetic algorithm (GA) is employed for the global optimal solutions in a concurrent fashion. The performance and capability of various surrogate modeling approaches—i.e., Gaussian process (GP), artificial neural network (ANN), and support vector regression (SVR)—are also investigated and compared in terms of accuracy, robustness, and efficiency. The examples presented in this paper show that the adaptive optimization procedure helps engineers determine optimal process conditions more efficiently and effectively.
Mathematical Model and Numerical Analysis of Polymer Melt Flow and Heat Transfer in a Cooling Extruder
This paper presents a mathematical model and numerical analysis of momentum transport and heat transfer of polymer melt flow in a standard cooling extruder. The finite element method is used to solve the three-dimensional Navier–Stokes equations based on a moving barrel formulation; a semi-Lagrangian approach based on an operator-splitting technique is used to solve the heat transfer advection–diffusion equation. A periodic boundary condition is applied to model fully developed flow. The effects of polymer properties on melt flow behavior, and the additional effects of considering heat transfer, are presented.
Compressed Viscose Sponges as Actuators
Compressed viscose sponges can be applied in devices in which a force is exerted when the compressed sponge is wetted. These sponges are used as actuator in a device to rescue keys attached to the floating device when it drops in water.Experiments have been carried out to determine the magnitude of the exerted force as a function of the mass of compressed sponges, but also as a function of the gap between the sponge and the object on which the force is exerted.From the experiments it was learned that the gap is predominant. Compressed sponges exert a force which is more than 4 times higher than the case when a gap of more than 1.5 mm exists.
Characterization of Model Urethanes and Ureas Based on Hydrogenated Methylenediphenldiisocyanate via Solution and Solid State NMR Spectroscopy
Models for hard-block segmented polyurethanes were synthesized using a pre-polymer process. Urethane linkages were synthesized using hydrogenated methylenediphenyldiisocyanate (H12MDI) reacted with dimethylol propionic acid (DMPA) and hexanol. Urea linkages were synthesized using H12MDI and hexylamine. The resulting small molecules were then subjected to solution and solid state nuclear magnetic resonance (NMR) spectroscopy to determine the reaction coordinates, to investigate possible side reactions, and to document 13C peaks and reaction times.
Failure Analysis of Polypropylene Used in a Hot Water Environment – Effect of Different Stabilizer Systems
Polypropylene has been used for many years in hot water applications with varying degrees of success. Failures in one instance were traced to a stabilizer package that inadequately protected the polymer in a hot, chlorinated water environment. This same stabilizer system performed extremely well in oven aging tests. The current study involved examination and analysis of failed samples from the field, along with laboratory aging studies designed to replicate the field failures and compare the performance of the stabilizer system in different environments.
New Materials from Polylactide Bioplastics
Renewable resource based bioplastic are the next generation of materials, which will play a major role in building of a sustainable bioeconomy. Polylactide (PLA) is a renewable resource based bioplastic. The realm of PLA bioplastic is expanding through innovative research methodology, products and processes. There is pressing want to enhance the versatility of this bioplastic, so that it can compete with conventional polymers. Inclusion of nanostructures in polymeric matrices is looked upon as unique approach to create revolutionary material combinations. Harnessing the benefits of nanotechnology in generating new biobased material is considered as a benign approach. Biodegradable polymer-clay nanocomposites have already been explored extensively. The niche application of nanotechnology to bring breakthrough research in the field of biobased polymer is still elusive. Recently, polylactide (PLA) has been modified with a new technology based on nanoscopic hyperbranched polymers (HBP) at Michigan State University. The modified PLA has shown a unique balance of stiffness and toughness. Such modified PLA bioplastic will act as ideal matrix for nano-clay, talc as well as natural fiber reinforcements leading to the development of new materials from PLA bioplastics.
Phosphate Esters as Stress Crack Agents – Case Studies in Failure Analysis
With a recent push toward non-brominated flame retardants, phosphorus-based alternatives, such as phosphate esters, are used more frequently for various applications. Their use as plasticizers is also well known. However, their function as environmental stress crack agents of various thermoplastics is less well recognized. Two case studies, one - in which a triaryl phosphate was a component of the formulation, the other – in which it was migrating from an adjacent component illustrate some of the problems with their use. Fractographic analysis and various analytical techniques were used to determine a root cause of each of the two failures.
Multilayer Films of Ethylene Co-Vinyl Alcohol Nanocomposite and Polypropylene for Food Packaging Applications
Retort is a high temperature sterilization process that is used to prolong the shelf life of military rations. Ethylene co-vinyl alcohol (EVOH) /montmorillonite layered silicate (MLS) nanocomposites were co-extruded with retort grade polypropylene (PP) into a multilayer cast film to determine if the addition of MLS to EVOH improved barrier, mechanical, thermal and retort properties. The PP/EVOH-MLS/PP structure showed an improvement in some properties such as water vapor transmission rate, Young's modulus, and seal strength before retort in comparison to the PP/EVOH/PP structure; however, the improvement in properties was lost after the retort process.
Structure and Properties of ?-Polypropylene Cast Films
The effect of ?-nucleation on structure and properties of cast films manufactured from isotactic polypropylenes has been studied. Two commercial-available polypropylenes – homopolymer and random copolymer – were modified by 0.03 wt.% of specific ?-nucleating agent NJ Star NU 100. Cast films were extruded from both starting and nucleated polypropylenes using a slit die and water-cooled chill roll. Supermolecular structure of the films was evaluated using wide-angle X-ray scattering. Tensile testing was used for the preliminary measurement of mechanical properties. A significant effect of the nucleation and solidification temperature on structure and properties of the films was found.
Advancements in Super Low Gloss ABS
The character and impression of an automobile interior is greatly influenced by the gloss and appearance of the interior components. This can have far reaching implications on the choice of polymer for molded-in-color parts. Acrylonitrile-Butadiene-Styrene (ABS) and talc filled Polypropylene (PP) resins are both widely used in such applications and each have their advantages and disadvantages, especially in respect to low gloss aesthetics and scratch resistance. Dow Automotive has recently developed a next generation of super low gloss ABS resins for interior applications, called MAGNUM* SLG ABS.Tool and part design for low gloss aesthetics using ABS resins and talc filled PP resins requires specific attention with respect to filling pattern and process conditions. Talc filled and impact modified PP resins are widely used for interior applications including instrument panels, door parts and pillars due to the versatility in part design and superior aesthetics. The impact-stiffness balance of mass-solution produced high impact ABS is very similar to talc filled impact modified PP, but ABS exhibits superior scratch resistance. Often, the Automotive Original Equipment Manufacturer (OEM) will set sixty degree gloss targets, for example between 1.8 and 2.5 for talc filled PP on specific grain types and/or textures. Achieving these gloss targets, whilst maintaining good scratch and mar behavior is heavily dependent on the texture applied on the mold surface. In an attempt to balance this demand between gloss and scratch and mar performance, additional mold surface treatments are becoming increasingly widespread in the industry. While in the first instance following seemingly opposing routes to achieve the same goal, we shall highlight the synergy achieved between super low gloss resins and secondary mold etching technologies.With this new development the aesthetical shortcomings of ABS resins have been resolved giving the part designer another material option for uncovere
Monitoring Curing Reactions of Thermosets under High Pressure by Use of Raman Spectroscopy
Reactions of many thermosetting materials may be monitored by the use of Raman Spectroscopy. It allows accurate online reaction monitoring for precise curing analysis. Curing is monitored through direct molecular changes thus reducing inaccuracies present when relating macroscopic variables to molecular level reactions. From the spectral changes in peak height or peak area, the curing behaviors were monitored. A high pressure reaction vessel has been designed with a fully automated temperature control, for monitoring the curing of unsaturated polyester and other thermosetting materials under high pressure or vacuum. Processing conditions such as heating rate and pressure will be related to the reaction conversion and material properties. The curing results for unsaturated polyester and epoxy reactions at constant pressures up to 2000psi will be presented.
Failure Mechanism of Panel Leak Formation in Solution Containers
Large-volume flexible solution containers are gaining in popularity in the medical products arena in recent years. The composition of these products often involve materials other than PVC. These products present peculiar engineering challenges, particularly in relation to the formation of panel leaks during packaging, storage, and distribution, due in large part to the volume of solution in the container. An extensive investigation of these panel leaks led to the elucidation of a multi-step failure mechanism. Understanding the failure mechanism directed efforts to enhance the robustness of the final product.
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