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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Morphological Development of Latex Particles in a Solvent-Free Extrusion Process
This paper reports on the influence of factors involved in the preparation of polyester latex in an aqueous medium using a twin screw extruder. In this work, screw speed was found to have no influence on the residence time (or axial mixing) in the process while the resin-to-water ratio in the early dispersion zone appeared to significantly affect both residence time and particle size. In an attempt to visualize the melt in the dispersion zone, conditions inside the extruder were used to hamper phase inversion. A morphological study of samples under such conditions by scanning electron microscopy showed a bi-continuous matrix formed stratified fibrils and nodular-extended clusters as mechanical action worked to increase the interfacial area between the water and resin leading up to the phase inversion point. Increasing the water content in the dispersion zone had the qualitative effect of increasing the presence of the bicontinuous morphology.
New Polycarbonate-Polysiloxane Copolymer Blend Resins for Consumer Electronic Applications
Developments in mobile phone housings place more and more demanding requirements on thermoplastic materials with respect to impact, flow and chemical resistance. Polycarbonate-polysiloxane copolymer resins offer significant improvements in low temperature impact and chemical resistance compared to polycarbonate resins. This improvement is most significant at high polysiloxane contents, but such copolymer resins can suffer from aesthetic issues, like pearlescence and gate blush, due to the presence of relatively large siloxane domains within the polycarbonate matrix. This paper discusses new polycarbonate-polysiloxane copolymer blends that offer good chemical resistance and excellent flow and low temperature impact, with aesthetics very similar to polycarbonate resins.
Improved Nanocomposite Dispersions Produced by a Melt-Mastication Process
Described is a new processing technique termed Melt-Mastication (MM), for improved nanocomposite dispersion. Compared to a conventional melt processing technique, MM improves the dispersion of fumed silica, halloysite nanotubes, and expanded graphite in isotactic polypropylene (iPP) and linear low density polyethylene (LLDPE). Transmission optical microscopy shows MM fragments nanoparticle clusters above a critical size (~8-10 ?m). Differential Scanning Calorimetry indicates the crystallization temperature increases for composites processed by MM. Modest improvements in storage modulus (5-7%) are also observed after MM. Melt-Mastication employs conventional processing equipment, and therefore presents a promising opportunity to improve commercial processing of polyolefin nanocomposites.
High Flow SF Ultem™ Resin Materials for High Heat Thin Wall Consumer Electronics Application
Trends in consumer electronics towards design freedom, miniaturization, high modulus, weight reduction and lower system costs have resulted in an increased usage of high flow high heat thermoplastics. SABIC recently introduced its Ultem™ SF resin portfolio, a family of high flow glass filled polyetherimide polymers. The resin has outstanding mechanical properties and dimensional stability at elevated temperature and increased flow ability compared with that of the traditional GF filled Ultem™ resin grades. This paper will compare properties of Ultem™ SF resins with the GF PES materials. Some potential application of Ultem™ SF resin grades will also be discussed.
Reactive Extrusion of Cross Linked Block Copolymers - Structure and Potential as Impact Modifier for Pa 6
Recent studies show that blending PA 6 with a novel polyether block copolymer results in blends with high impact strength and high stiffness compared to conventional rubber blends. The block copolymers used as impact modifiers were prepared by continuous anionic polymerization in a reactive extrusion process (REX) using a twin screw extruder. They are semi crystalline and partially cross linked in contrast to commonly used amorphous and uncured rubbers. The structure of the blends was analyzed using different analysis methods like atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Due to the cross linked structure of the block copolymers, the particles in the blends are not spherical like the particles of conventional rubbers. The differences in molecular structure, miscibility and grafting of the impact modifiers result in different mechanical properties and very different blend morphologies.
Coatable Wood Plastic Foams for Automotive Applications
The automotive Industry is searching for lightweight materials to decrease the energy that is needed to move a car. Especially materials that can be used for mass production are requested. Assisted injection molding methods like the water injection process are capable to fulfill these requirements. Another possibility to make thermoplastics even more light is to foam them, this causes a loss of mechanical strength. To improve the strength of the foamed material, natural fibers (NF) can be embedded. Both, the foaming and the use of NF, lead to an unsightly surface. So the surface on the exposed side has to be painted. State of the art is to coat plastic surfaces with polyurethane (PUR) . In this study an acrylonitrile butadiene styrene (ABS), reinforced with wood fibers (WF), was foamed. One aspect of the material choice was that it can be coated with PUR in a one-shot-process. The mechanical properties of NF and foam modified ABS compounds were investigated. The adhesion between ABS and PUR was also verified.
Material Concept for Large-Scale Production of Finished Colored External Body Panels in Automobile
Lightweight construction is the elementary key of the Volkswagen CO2 reduction strategy. The goal is to design a car which is efficient as possible. The reduction of energy usage during production of the car as well during moving the car leads to research of new materials and new applications in the automotive Industry. The Volkswagen CO2 reduction strategy has three Main topics: • The right material at the right place • Reach the best Customer satisfaction • Use of new Technology including multi material design for Steel, Alumina, Plastics In the case of Plastics is the use of foamed polymers in combination with In-Mold coating is one focus of Volkswagen research. The following paper shows general lightweight aspects as well the topic “class A” surface for foamed body panels with the goal to use this process in a large scale.
The Effect of Reprocessing on Mechanical Properties of Polypropylene
Polypropylene (PP) was injection molded up to 20 runs to study the effect of recycling procedures. The influence of the recycling was studied by observing changes in melt viscosity, tensile and impact resistance properties. The main effect of recycling was decrease in melt viscosity, which is attributed to molecular weight reduction. The observed degradation processes only slightly affected the small strain properties of the materials studied. However, break properties were affected apparently. All the tensile properties related to breaking as well as impact resistance of recycled polypropylene decreased with recycling.
Formation of Part Defects in Water-Assisted Injection Molding (WAIM): Influence of Process and Material Parameters
Water-assisted injection molding (WAIM) enables the production of hollow or partially hollow products, having a higher quality and lower process cost when compared to products produced with other and earlier developed plastic processing techniques. However, the occurrence of (unwanted) defects in the final product is one of the current limitations of the WAIM process, for which in available research until now no clear explanations exists. In this study, the influence of process and material parameters on the occurrence of part defects was examined in a pre-defined reference experiment. With a qualitative defect analysis, it was found that within the reference setting a high water temperature, a low melt temperature and water holding pressure as well as the addition of nucleating agents are more favorable. The experimentally observed changes in defect occurrence, under influence of the applied parameter variation, can herewith be explained with the proposed definitions of the different defect types and their responsible formation mechanisms. In this way, the principle mechanisms behind the formation of part defects are enclosed in these definitions and mechanisms, which hence contribute to a more fundamental understanding of the WAIM process.
Binary Blends of Cycloolefin Copolymers
Binary blends of different grades of cycloolefin copolymers (COC) were prepared at different compositions via compounding in a twin-screw extruder. Thermal, mechanical and rheological properties of the COC blends were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and rotational rheometry. Results revealed the differences in the miscibility of different grades of COCs. This could be attributed to differences in the microstructures of the COCs determined by their synthesis method (catalyst type) and norbornene content of each component. Blends of Topas 8007 and Topas 5013 were immiscible but they were compatible to a certain degree. Two distinct Tg’s were observed at DSC and DMA, with a slight shift upon changing the composition of the blends. DSC data was used to model this behavior using two parameter Kwei model for the prediction of the Tg for the immiscible COC blends (8007/5013). Rheology data of the blends revealed that the phase inversion occurs at 45%-55% for the blends of two different Tg COCs. On the other hand Topas 8007 and Topas 6013 blends were miscible and single Tg was observed at DSC. Fox equation was used to model the Tg behavior of the miscible blends and the experimental results were in close agreement with the model.
Physics-Based Film Blowing Modeling to Enhance Empirical Film Property Predictions from Polymer and Processing Parameters
In this paper physics-based modeling of the film blowing process is combined with empirical film property relations. A hybrid approach for polymer processing-property prediction is provided. A continuum mechanics model is implemented to enhance the nominal fabrication input with calculated stresses, strains, and related parameters. Nominal and calculated parameters are candidate inputs for empirical property prediction. Data is used from various (linear low-density polyethylene) LLDPE resins, run under different conditions at laboratory and commercial-scale film blowing lines. The results based on temperature-dependent Newtonian constitutive relation indicate that the strategy lead to significant improvement of a quality of prediction of certain film properties.
Curing Study of a Green" Thermosetting Resin"
A series of green" thermosetting resins oligomers of bis(hydroxyalkylene)-2-mercaptosuccinate has been reported recently . Curing in these thermosetting resins results from crosslinking via pendant thiol groups. As part of an effort to realize and assess the potential of these resins as sustainable materialsthe curing process was investigated using differential scanning calorimetry (DSC) and rheology. The progression of physical and mechanical properties such as the glass transition temperature (Tg) and the shear moduluswas monitored as a function of time and temperature. Tg of the resin was found to increase with curing and the averaged Tg of the fully cured resin was found to be 72.6 K ± 1.2 K higher than uncured resin. The increase in Tg corresponded with the change in rheological properties. The shear modulus obtained for fully cured samples reached a high modulus of 6.5 × 106 Pa at 200 °C. Additionallythe gel point was measured from the crossover of the storage and loss moduli. Based on the gel points the apparent activation energy of curing also was determined."
Unexpected Dependence of Hydrolytic Performance of PC/ABS Blends: Specificity of Buffer Cation Type
Compromised performance of hydrolytic stability has previously been shown in emulsion-ABS impact modified PC blends, resulting from acidic residual surfactants and coagulants in the impact modifiers. To neutralize the residual emulsifiers and coagulants in emulsion-ABS, buffers were added to the blends during the compounding step. A comparison of PC molecular weight retention upon hydroaging between blends with added buffers in different cation forms revealed enhanced hydrostability in blends added with a cation specific buffer. The addition of buffer containing the specific cation presented here holds promise as an effective strategy for improving hydrostability in PC/emulsion-ABS blends during compounding.
Thermal and Rheological Behavior of Plasticized Polyacrylonitrile and Melt Spinning of Precursor Fibers
While there is tremendous interest in the melt spinning of polyacrylonitrile (PAN) with presence of plasticizers, the behavior of plasticized PAN melt and the spinning process have not been adequately investigated so far. In this paper the melting and rheological behavior was studied for PAN plasticized with water or water and a second plasticizer. A lab scale pressurized fiber spinning system was developed and used to generate melt-spun fibers as carbon fiber precursors. The morphological and mechanical properties of the fibers were evaluated and compared with commercial wet-spun fibers. The meltspun PAN fibers have surface and mechanical properties similar to those of commercial fibers.
Morphological and Rheological Properties of PBS/Silica Nanocomposite Manufactured Using a High-Speed Twin-Screw Compounder
The effects of silica chemistry and high-speed compounding on the morphology and rheology of poly(butylene succinate) (PBS)/fumed silica nanocomposites were investigated in this work. The filler content of the nanocomposites was determined by thermogravimetric analysis and matched estimated values well. Depending on the distribution and surface chemistry of fillers, distinct surface texture could be identified in the PBS/silica nanocomposites. Using high-speed mixing and compatibilizing surface functionalizations can result in enhanced polymer-particle interactions and influence the composite rheology dramatically. The relaxation hierarchy can be identified from the linear viscoelastic response of PBS compounded with mixture of modified and pure fumed silica particles.
Composition Dependence on the Mechanical Behavior of Hydrophobic Lignocellulose-Reinforced Poly (Trimethylene) Terephthalate Composites
Lignocellulosic fiber-reinforced thermoplastic composites offer many property and environmental benefits. The major issue to overcome is moisture absorption due to the hydrophilic nature of the lignocellulosic component. The aim of this work is to combine hydrophobic natural fibers (NF) and a thermoplastic to produce a novel wood polymer composite that offers moisture resistance, dimensional stability, and resistance to microbial attack. Hydrophobic NFs are combined with polytrimethylene terephthalate using a novel, injection molding method and the flexural, tensile, and impact resistance mechanical properties presented.
Property Development of Semi-Crystalline Polymers in Sintering Processes
In additive manufacturing processes such as Selective Laser Sintering (SLS) and Selective Mask Sintering (SMS), shrinkage and warpage effects tend to be some of the major sources of error that affect dimensional stability and part quality. Most of these inaccuracies are due to thermal processes that take place over time. The present work includes an experimental and analytical approach to study the relationship between crystallization and development of mechanical properties over time during the sintering process. These properties are necessary when predicting shrinkage and residual stress build up during the crystallization process.
Post-Consumer Recycle (PCR) Solution for PC/ABS Blends
To meet the continued commitment on environmental sustainability, SABICTM has developed and commercialized PCR PC/ABS blends portfolio, which provide more options for customer to choose Cycoloy product. PCR Cycoloy grades are all PC/ABS blends containing 30~35% recycled polycarbonate from post-consumer CD and/or water bottle. RCM6123 and RCM6134 are filled grades, while RCY6214, RCY6113, RCY6013 and RCY6713 are non-filled. These grades were developed for various applications with additional value on environmental sustainability. At the same time, in most applications they showed comparable properties to corresponding virgin grade.
Vapor-Foamed Injection Molding of Polycarbonate Using Sodium Chloride and Active Carbon as Nucleating Agents
This paper presents a new process for producing vapor-foamed polycarbonate (PC) parts using water vapor as the physical blowing agent and two kinds of nucleating agents, namely, sodium chloride (NaCl) particles and active carbon (AC) powder. The effects of these two nucleating agents on the surface roughness, mechanical properties, and microstructure of solid and foamed parts were characterized. The results were compared with microcellular injection molded parts using supercritical fluid (SCF) nitrogen as the physical blowing agent without a nucleating agent. The water vapor-foamed PC parts with NaCl as the nucleating agent had a smooth surface comparable to that of solid injection molded parts. Foamed PC parts with AC had desirable specific mechanical properties as well as an advantageous average weight reduction of 16.4 wt%. AC powder, serving as nucleating agents, water carrier, and reinforcing fillers, positively improved the microcellular structure and mechanical properties of vapor-foamed PC parts. Based on infrared spectrometry (IR) and gel permeation chromatography (GPC) results, the melt compounding processing to incorporate the nucleating agent and the vapor-foaming process caused minor thermal degradation and hydrolytic degradation, respectively. Without the nucleating agent, vapor-foamed PC parts exhibited much larger and fewer bubbles within the molded parts.
Enhancing Cell Nucleation for a Novel Microcellular Injection Molding Process Using Gas-Laden-Pellets
A novel and cost-effective method of microcellular injection molding using gas-laden pellets has been developed. In this study, several methods, as well as their combinations to enhance the gas-laden pellets’ foamability, have been attempted including (a) enhancing homogeneous nucleation by blending N2- and CO2-laden pellets to create an N2/CO2 synergetic effect, (b) enhancing heterogeneous nucleation by incorporating talc as a nucleating agent, and (c) enhancing heterogeneous nucleation by compounding PP/HDPE immiscible blends. The results show that these methods effectively improved the cell nucleation rate and cell morphology. Moreover, it was found that these methods could also be superimposed on one another without conflict, thus leading to further improvements.
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