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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Modification of High Flow Polypropylene by Ethylene/a-Olefin Elastomers Produced by Single Site Constrained Geometry Catalyst
The recent advent and commercialization of technology using single site, constrained geometry catalyst has made possible the introduction of unique ethylene/a-olefin elastomers with novel molecular architecture. These advances in elastomer technology have resulted in differentiated materials capable of impact modifying polypropylene polymers thereby offering new TPO blends with enhanced properties. This paper will explore high flow polypropylene blends modified with this distinct class of elastomers and will discuss the influence of elastomer comonomer choice, molecular weight and crystallinity along with discussions on the effect of dispersion, morphology and rheology.
Modification of Nylon-6,6 through Solid-State Polymerization in Supercritical CO2
The solid-state polymerization of nylon-6,6 has been studied in the presence of supercritical (SC) carbon dioxide (CO2 ) in a small autoclave. Experiments have been carried out under varying pressure and temperature conditions at several reaction times. In addition, experiments have been performed in the presence of nitrogen (N2) which is commonly used in commercial solid-state polymerization processes. The results indicate that the samples produced in the presence of CO2 have higher molecular weight and viscosity compared to those produced in the presence of N2 under the same reaction conditions. Furthermore, the polyamides produced in SC-CO2 have higher end group differences.
Modification of the PP/HDPE Blend and the PP/HDPE/Woodflour Composite Using Peroxide
The mechanical, thermal and rheological behavior and the morphology of a Polypropylene (PP)/high density polyethylene (HDPE) blend and of the PP/HDPE/Woodflour composite, both modified with peroxide, were evaluated. A decrease in the apparent viscosity of the blends with the increase in the content of peroxide was found. None of the peroxide modified samples showed significant variations in the melt and crystallization temperatures. The blend modified with 0.04 phr of peroxide showed the highest Young's modulus of all. The woodflour produced a significant increase in the viscosity and the Young's modulus of the composite.
Moisture as a Foaming Agent in the Manufacture of Rigid PVC/Wood-Flour Composite Foams
Relationships between the density of foamed rigid PVC/wood-flour composites and the moisture content of the wood flour, the chemical foaming agent (CFA) content, the content of all-acrylic foam modifier, and the extruder die temperature were determined using a response surface model (RSM) based on a four factor central composite design (CCD). The experimental results indicated that there is no synergistic effect between the CFA content and the moisture content of the wood flour. Wood flour moisture could be used effectively as foaming agent in the production of rigid PVC/wood-flour composite foams. Foam density as low as 0.4 g/cm3 was produced without the use of chemical foaming agents. However, successful foaming of rigid PVC/wood-flour composite with moisture contained in wood flour strongly depends upon the presence of all-acrylic foam modifier in the formulation and the extrusion die temperature. The lowest densities were achieved when the all-acrylic foam modifier concentration was between 7-phr and 10-phr and extruder die temperature was as low as 170°C.
Mold Design and Manufacture an Approach to Innovation and Sustained Development
The Portuguese mouldmaking industry has a driving force for competency and innovation. This attitude relies on the embodiment of the latest developments in science and technology. In 1999 the University of Minho was challenged to design a course to materialize that purpose.This idea sprung from one of the regular meetings of the Advisory Council to the Department of Polymer Engineering involving representatives of the Plastics and Moldmaking Industries and the University of Minho. As a result an MSc course is now running in cooperation with the industry.This initiative deserved the interest of the Agency for Innovation within the Ministry for Science and Technology, who meant it to be a stimulus and commitment to the joint initiatives towards the improvement of the know-how in the fields of molds and plastics, involving the government, the industry and the university.The course includes core subjects as Injection Molding or Manufacturing, and options as Communications Networks or Rapid Tooling Prototyping.The globalization of science and technology suggests this experience being open to other countries, for example developing an English version of the course with international cooperation of specialists.
Monitoring the Changing State of a Polymer Using Insitu Frequency Dependent Dielectric Sensors during Polymerization, Fabrication and Use
Essential to 'intelligent manufacturing' and 'smart materials' is the ability to monitor the state of a polymer resin as it is synthesized in a reactor, as it cures during fabrication and as it ages during uses in the field. Important aspects of this sensor monitoring capability are: in situ, on-line measurement; that the signal output be related to the relevant processing and use properties; sensitivity with long-term reliability in a manufacturing and field environment. This paper addresses how to successfully use in situ dielectric sensor measurements to monitor the changing state of a polymer resin during fabrication and/or use both in the laboratory, in an industrial plant, and during use in the field. The talk will address thermoset and thermoplastic materials as neat resins, composites and coatings.
Morphogloy Evolution of Binary Polymer Systems Using Microfabricated Samples
Binary polymer blends with well-defined initial structure were prepared by Computer Numerical Controlling (CNC) machining, photolithography and micro-embossing. Using the methods, we designed the size and distribution of the dispersed phase and the composition of the blends. Compatibilizer can also be easily placed at the interface of the two components during sample preparation. With the micro-fabricated samples, the dynamics of phase inversion and the morphology evolution of binary polymer blends were studied in simple shear flow under isothermal conditions. The effects of interfacial tension, viscosity rate, blend composition, and shear rate on rheology and morphology evolution were investigated.
Morphological Development and Mechanical Performance of Injection Molded Starch Based Composites
Conventional injection molding and Multiple live Feed Molding (MLFM) has been used to process starch based biodegradable composites aimed for load bearing bone replacement/fixation applications. Blends of starch with : (i) poly(ethylene vinyl alcohol) and (ii) cellulose acetate were studied. Both polymers were reinforced with bone-like ceramics (hydroxylapatite) in amounts up to 50 % wt.. The use of MLFM allowed for the inducement of molecular anisotropy into the moldings. However it was necessary to prevent material degradation associated to shear dissipation effects and to the longer residence times.
Morphological Studies on Poly (Trimethylene Terephthalate) (PTT) / Clay Nanocomposites
A series of intercalated Poly (trimethylene terephthalate)/ montmorillonite (PTT/MMT) nanocomposites were produced by a melt intercalation process. The PTT/MMT nanocomposites were shown to have similar d-spacing, about 3.1nm. More coherent stackings of silicate layers were observed at higher clay concentrations and shorter blending time. Compared to conventional PTT filled with MMT, the nanoscale dispersed MMTs are more effective nucleating agents and enhance the crystallization of PTT. The influence of nano montmorillonites on the crystallization and melting behavior becomes distinct when the concentration of MMT is greater than 1%.
Morphological Study of Polyamide-6/Polysyrene/Polyethylene Ternary Blends
The morphology of Polyamide-6 / Polystyrene / Polyethylene blends was predicted based on spreading coefficient of three components, and the predicted morphology was compared with the actual blending morphology. Without any treatment such as compatibilizers and changes in mixing sequence during the melt blending, it has been observed that PE domains are exclusively located in the PS phase in PA6 matrix, as expected by the spreading coefficient. In this study, trials to control the locus of the PE domains were also performed. It should be noted that the locus of the PE domains is successfully controlled. Thus, the PE domains can be dispersed in PS phase exclusively, in PA6 matrix exclusively or both in PA6 matrix and in PS phase. Effects of SMA and PS on the PA6/PE blending morphology were also investigated. It was found that SMA reduce the size of the disperse PE domains dramatically, in spite of no specific interaction expected between SMA and PE. This phenomenon was successfully explained by the spreading behavior of PS on PE in PA6 matrix. A small amount of PS added also affects the co-continuity of PA6/PE blend.
Morphology and Properties of Oriented mLLDPE Films
Cast films of a metallocene Linear Low Density Polyethylene (mLLDPE) have been cold-drawn along MD in two sequential steps to form ultra-oriented films. The initial films are cast under low shear conditions to form essentially isotropic films. The first draw yields oriented films, which display block-shear type morphology. Under controlled conditions, void formation occurs during the second draw and the ultradrawn films whiten and display a fine crystalline morphology. In their ultra-oriented state, the water vapor transmission of the films is equivalent to that of poly(vinylidenedichloride) (PVDC). Independent experiments show that this ~13x decrease in the WVTR is due to an increase in the degree of crystallinity and increase in tortuosity due to the blocky crystalline morphology. Additionally, it is hypothesized that an increase in the amorphous phase density also contributes to the decrease in permeability.
Morphology and Stress-Relaxation of Biaxially Oriented Crosslinked Polyethylene Films
In the present work the morphology and stress-relaxation of crosslinked polyethylene films were investigated. The stress-relaxation of crosslinked films was studied as a function of temperature and as a function of the irradiation dose applied. The relaxation time spectra of crosslinked films were observed to display additinal relaxation times. Irradiation dose and temperature were shown to influence the relaxation time spectrum of crosslinked and non-crosslinked films. The crystallization of crosslinked and non-crosslinked polyethylene was compared. It was shown that the lower mobility of the crosslinked molecules affects the final crystal size.
Morphology Development in I-PP Articles Moulded via Cryogenic Gas-Assisted Injection Moulding
The current experimental study investigates the development of the micro-morphology across the residual wall thickness and along the gas channel of specimens moulded via a recently developed cryogenic gas-assisted injection moulding process. This novel method was developed as an alternative to conventional gas-assisted injection process (GAIM), targeting cycle time reduction by improving the internal heat transfer from the polymer melt to the gas. The cryogenic GAIM process employs the injection of nitrogen gas at cryogenic temperature into the polymer melt stream and its controlled manipulation throughout the gas holding phase. The effects on the morphology induced by the injection of gas at cryogenic temperature are investigated using polarised light microscopy and the results compared with the structure produced at conventional GAIM temperatures. Differential interference contrast (DIC) is used to characterise the morphology of the internal surface.
Multi-Component Laminate Moulding (MLM)
A new injection moulding technology is described in which a laminate structure of two or more polymers moulded in combination can be controlled. The new technology is referred to as 'Multi -Component Laminate Moulding (MLM) Technology'. The principle of the process is demonstrated with reference to a two component application. The material combinations chosen were a general-purpose polystyrene with a high-density polyethylene (GPPS/HDPE) and a general-purpose polystyrene with a high-impact polystyrene (GPPS/HIPS). The processing conditions, physical property and micromorphology relationships of conventional injection mouldings of the individual component materials were compared with multi-layer mouldings produced from them. Bright Surface Moulding (BSM) was also used to influence the layer structure of the multi-layer mouldings. The results of this study showed that the multi-layer mouldings composed of both combinations produced by MLM possessed desirable characteristics of both resins. The impact strengths of the multi-layer mouldings were, however, found to be in the range of 1.5 to 10 times greater than that of the individual components. It was also shown that the MLM process could be applied to component resins that have a large difference between their viscosities.
Multlayered Monocomposite Polypropylene
Multilayered monocomposite polypropylene is a new composite material. It captures the exceptional mechanical properties of oriented polypropylene tapes in a polypropylene matrix.Low density, high stiffness, high tensile strenght and outstanding impact and abrasion resistance provide the opportunity to make parts with an extraordinary performance. Due to missing reinforcement fibers like glass or carbon fibers this material is a 100% thermoplastic and totally recyclable.This paper describes the influence of manufacturing parameters (pressure, temperature, time) on semi-finished material. Afterwards an exemplary vehicle application is discussed with attention to the specific advantages of this material.
Nanocomposite Modeling and Simulation
Nanocomposite polymer films are known to exhibit increased barrier properties at low additive loadings. These films, particularly at low loadings, are of interest to the food packaging industry. Current 2D models do not fully account for the characteristics of typical polymer-clay systems. The results of a new permeation simulation using Monte Carlo techniques will be presented.Efficient Monte Carlo simulations were run in three dimensions to determine the effective diffusion coefficients for typical polymer-clay systems. Systems with loadings between 0.5 and 50 vol% were simulated. The results were compared to existing models to examine the effects the added dimension had on the diffusion coefficient. The results were also viewed using Java3D to examine the diffusion path.
Nanocomposites Study of Ethylene Co-Vinyl Alcohol and Montmorillonite Clay
Nanocomposite films consisting of an ethylene co-vinyl alcohol (EVOH)/clay system were investigated to determine the effect of the nanoclay on the film properties. EVOH and montmorillonite clay at 5% loadings were compounded using a twin-screw extruder. Subsequently, these formulations were further processed into blown films using a twin-screw extruder. The morphological, mechanical, thermal and barrier properties of the films were examined. The delamination and dispersion of the clay improved in the blown films compared to the compounded material. Young's modulus and tensile strength increased significantly for the nanocomposite compared to the pure EVOH. Dramatic reduction of oxygen transmission rates occurred as a result of incorporation of the nanoclays. With improved barrier properties, these films could be used in military ration packaging systems in order to meet shelf life and survivability requirements.
Nanocomposites: A Single Screw Mixing Study of Nanoclay-Filled Polypropylene
Polypropylene (PP) nanocomposites were prepared by two steps: a predispersed organoclay masterbatch was first prepared by using a twin screw extruder; the masterbatch was then letdown into base PP by using a single screw extruder. The effect of single screw mixing type on organoclay dispersion and nanocomposite properties was evaluated. The results indicated that the composites obtained from the masterbatch letdown with a single screw extruder showed better dispersion and better mechanical properties than the composite obtained from the direct compounding with twin screw extruder. Furthermore, the mechanical properties of these composites from masterbatch single screw letdown process is as good as the composite obtained from masterbatch letdown with a twin screw extruder. A rheological study also shows PP nanocomposite has the same flow characteristics as neat PP, indicating the new technology can drop in the current machine set up, without adding additional cost to end users.
Natural-Fiber Composites of High Performance Thermoplastic Polymers
A new method was investigated for development of natural fiber composites of high performance thermoplastic polymers considering polyphenyleneether (PPE) and wood flour as example system. The large gap between high processing temperature of PPE, typically between 280-320°C, and low decomposition temperature of wood flour, about 200°C, was reduced by using a reactive solvent, a low molecular weight epoxy. The epoxy component reduced viscosity of the blends and accumulated around polar wood flour particles upon polymerization during the fabrication step. These composites offered lower density and better mechanical and physical properties than commercial engineering polymer blends filled with short glass fibers.
A New Approach of Parts Design for FMVSS201U Using Simple Deformation Model and CAO Technique
To reduce head injury of occupants in automobiles, The National Highway Traffic Safety Administration published FMVSS201U that ruled required parts performance of impact energy absorption using HIC(d) calculated from time-acceleration curve of Free Motion Head Form (FMH) . From the complexity of the calculation, it is difficult to design time-acceleration curve which minimizes HIC(d). In this paper, we propose a method of minimizing HIC(d), using CAO (Computer Aided Optimization) technique and deformation model which is constructed with energy balance between interior parts and FMH. As the results, we get time-acceleration curves which make HIC(d) smaller than rectangular wave.
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