SPE Library

The mechanical properties and crystallization behaviors of PP/acrylonitrile-butadiene-styrene/organic montmorillonite nanocomposites (PP/ABS/OMMT) were studied. It was shown that compatilizer PP-g-MAH not only improved the compatibility of PP/ABS but also promoted the dispersity of OMMT particles in continuous phase PP and dispersed phase ABS. In addition PP was reinforced and toughened by both layered silicate OMMT nanoparticles and ABS. The blend weight ratio of PP/ABS/OMMT which was 85/15/2 wt % had a concerted effect on toughening. OMMT nanoparticles also increased crystallization temperature and crystallinity.

The mechanical properties and crystallization behaviors of PP/acrylonitrile-butadiene-styrene/organic montmorillonite nanocomposites (PP/ABS/OMMT) were studied. It was shown that, compatilizer PP-g-MAH not only improved the compatibility of PP/ABS, but also promoted the dispersity of OMMT particles in continuous phase PP and dispersed phase ABS. In addition, PP was reinforced and toughened by both layered silicate OMMT nanoparticles and ABS.The blend weight ratio of PP/ABS/OMMT, which was 85/15/2 wt %, had a concerted effect on toughening.OMMT nanoparticles also increased crystallization temperature and crystallinity.

In order to assure the part quality in the part design step, it is desirable to optimize the cooling circuit prior to the mold design step. In the environment of frequent design changes, a way to optimize automatically the cooling circuit in a short period of time is necessary. In this work, an automated optimization of the cooling circuit was examined with a commercial optimization tool, PIAnO. The optimization technique is useful largely for large parts such as instrument panels and bumpers. The objective function is the deviation of temperature difference from a target mold surface temperature.

In this paper, we will discuss several companies who have not seen recessions as a deterrent to innovation but an opportunity. Using a case study format, we will discuss four companies that have innovated in a recessionary environment. We will derive the lessons learned and offer some recommendations as to ƒ??how toƒ? look for the silver lining in an economic downturn. The objective of this paper is to present examples of companies that re-positioned for growth during an economic downturn. In two of the cases, an innovative business grew out of adversity. The third is a new company that was able to identify a technology developed earlier but eventually abandoned due to a lack of a market. The last invested while its competitors contracted. Due to the poor economy, most of us are experiencing a drop in our business and are looking for ways to reposition our businesses. Our businesses are down as much as 50% from prior years. We have cut our costs, reduced our payrollsƒ??what do we do nowƒ?? The following four companies are examples of what can be done to innovate in a recessionary environment. The following table shows the types of business segmentation opportunities.

A 100 000 g/mol polyethylene molecule has a crosssection of about 0.5 nm and a contour length of about 0.9 ?m. A typical single-walled carbon nanotube (SWCNT) has a cross-section of about 1 nm and a contour length of about 1 ?m. The critical difference from a physics perspective between these two molecules is that the persistence length of the former is about 0.6 nm and the persistence length of the latter is reported as ? 30 ?m.1 One can make a similar comparison between SWCNTs and liquid crystalline polymer molecules; in this case the key difference is that the length of the former is much larger than the length of the latter. This paper presents what is believed to be a synergistic type of behavior that is possibly related to the similarity in size of the two high aspect-ratio materials the fact that single-walled carbon nanotubes can increase the jump in heat capacity at the glass transition. Other measurements involving the behavior of fictive temperatures and activation energies measured from calorimetric studies are also given.

A 100,000 g/mol polyethylene molecule has a crosssection of about 0.5 nm and a contour length of about 0.9 ?¬m. A typical single-walled carbon nanotube (SWCNT) has a cross-section of about 1 nm and a contour length of about 1 ?¬m. The critical difference from a physics perspective between these two molecules is that the persistence length of the former is about 0.6 nm and the persistence length of the latter is reported as ƒ?? 30 ?¬m.1 One can make a similar comparison between SWCNTs and liquid crystalline polymer molecules; in this case the key difference is that the length of the former is much larger than the length of the latter. This paper presents what is believed to be a synergistic type of behavior that is possibly related to the similarity in size of the two high aspect-ratio materials, the fact that single-walled carbon nanotubes can increase the jump in heat capacity at the glass transition. Other measurements involving the behavior of fictive temperatures and activation energies measured from calorimetric studies are also given.

Conformal cooling channel could make the temperature distribution in the mold uniform, reducing cycle time and improving part quality. However, design principle for the conformal cooling channel has not been established yet. In this study, a constructal design principle was tried with hexagonal cooling channel. The size and the depth of the hexagonal cooling channel were optimized to minimize the temperature deviation of the mold surface. Constraint was pressure drop through the cooling channel limited by the pumping capability. The CAE tool for mold cooling analysis was Moldflow Cool.

A thermoplastic elastomer (TPE) blend of thermoplastic polyurethane (TPU) and polypropylene (PP) was sampled from extruded strands and injection molded plaques. Highly stretched strands of the PP phase are aligned parallel to each other along the extrusion direction in the extruded samples while in the injection-molded samples the PP phase is in ellipsoidal domains residing in the shear plane of the mold. Subjecting the samples to a tension load leads to rupture of the elongated strands, resulting in increased tensile set and reduced moduli. Annealing the extruded specimen at 150 oC for 30 min. can create cracks in the blend similar to those generated during tensile testing.

The foaming process of PMMA in specially designed rotor system with screws and previously designed rotor system without screw was studied respectively. In this study, with supercritical carbon dioxide (ScCO2) as a blowing agent, microcellular foam of PMMA was made in traditional steady process and dynamic vibration field respectively by using the isobarical feeding equipment of supercritical carbon dioxide and microcellular foaming simulator. The effects of processing parameters such as pressure, time of saturation, shear stress were investigated, in order to study and analyze the effects of processing conditions on PMMA microcellular plastics. Foamed samples with the cell density of 78.7??107 cell/cm3, average cell size of 12.6 ?¬m have been produced by using the screw system.

Wax formulations prepared using paraffin wax (PW) and hydrogenated resin (HR) were studied to identify effects of temperature and composition on phase homogeneity. A phase diagram was constructed showing regions of PW/HR miscibility and tracking changes in PW crystallisation as HR is added. Polarised optical microscopy identified changes in nucleation and crystal growth mechanisms of the PW semi-crystalline phase promoted by HR. A simplified wax injection system was used to investigate conditions for defect formation. Results, to be validated using a ProCAST model, showed defects occurred by injecting blend compositions corresponding to regions of PW/HR phase separation as shown by the phase diagram.

In the present study, the friction and wear properties of high temperature resistant polymers, Polyetherimide (PEI) and Polyetheretherketone (PEEK), have been investigated at specific combinations of high pressure, velocity and temperature against smooth steel counterparts. The effects of internal lubricant, polytetrafluoroethylene (PTFE) and PTFE with short fiber reinforcements (carbon fiber) are outlined. The tests were performed on a thrustwasher testing machine under dry sliding conditions. Different analytical techniques were employed to study the correlation between the transfer layer and friction properties. Lubricated and lubricated-reinforced compounds showed excellent wear resistance compared to pristine resins.

The mechanical properties and misconstrues of high impact polystyrene (HIPS) toughened by styrenebutadiene-styrene (SBS) were studied to find the Brittle-Ductile Transition Point. At the Brittle-Ductile Transition point, HIPS and SBS alloys were prepared using melt intercalation technique by blending HIPS and SBS while used acrylonitrile-styrene (AS) powder, gaining higher impact and tensile strength. Their microstructures near the Transition Point were characterized by scanning electron microscope (SEM) to investigate the toughening mechanism of HIPS/SBS/AS composites. The toughening mechanism is similar to the mechanism of RIF toughening rather than the cold-drawing theory which applied to ductile matrixes toughed by rigid organic filler (ROF).

Both polypropylene (PP) and polystyrene (PS) parts were molded by injection-compression molding. The Taguchi method was utilized to investigate the effects of six processing parameters including mold temperature compression speed compression time compression distance delay time and compression force on part shrinkage uniformity. Analyses of means and variance showed that the compression force is the most important parameter for part shrinkage uniformity of both parts. The compression distance is the second most significant parameter on shrinkage uniformity of PS part but not significant parameter on PP part. The optimal processing parameters for improving the shrinkage uniformity of both parts are found and verified experimentally.

Thermoplastics urethanes (TPU) offer broad property range, processing flexibility, and biocompatibility for medical applications. We have undertaken a thermal and rheological study on thermal transitions which influence physical characteristics and oxidative degradation. In addition, possible effects from hydrolytic degradation with long term exposure to alcoholic solvents are sought. Techniques used include Thermal analysis and oxidative induction time (OIT) by differential scanning calorimetry (DSC), and melt rheology. It was found, for selected but not the majority of TPUs, OIT onsets were difficult to obtain. However, melt rheology, with proper sample conditioning, was capable in quantifying the hydrolytic molecular weight degradation process.h

Clarified polypropylene (PP) continues to find increasing uses as polymer and additive improvements allow for its incorporation into applications where resins such as polystyrene or acrylics have traditionally been used [1]. Second and third generation clarifiers have improved the clarity, processing properties, and the organoleptic properties (residual odor and taste), opening the way for more extensive food contact applications [2,3]. With the expanded use of clarified polypropylene comes the need appropriate colorants which will give high clarity, low haze, deep coloration, and no migration. Polymeric colorants have shown to possess these properties, further expanding the market potential for clarified polypropylene. This paper will explore the use of various modified wax compounds and their effects on the residual haze of clarified PP molded with GemToneTM Polymeric Colorants.

This work reported the comparative study on polypropylene/clay nanocomposites. Commercial filler Dellite and modified micronized calcium were used as a nanocomposite filler for the PP-based composite. All nanocomposites were prepared by using Brabender kneader at different speeds of rotation; however, the compounding time was the same. X-ray diffraction and scanning electron microscopy (SEM) were used for evaluation of morphology. The mechanical properties were evaluated by results of tensile strength and the results were presented in graph. The model was used to predict of tensile strength.

Polymer foams prepared with supercritical carbon dioxide as a blowing agent have attracted much interest in recent years. Yet, a thorough understanding of the foaming process, especially nucleation, is absent. In this article, the influence of one characteristic property of polymer, molecular weight, on the nucleation rate and cell growth rate is investigated by an in-situ observation introduced by high speed camera. Moreover, the influence of these two properties on the solubility of carbon dioxide in the polymer is investigated by using a magnetic suspension balance while simultaneously measuring the swelling coefficient during adsorption.

This paper details the results from a large European Union rotomoulding research project on the adaptation and development of industrial microwave oven technology to the rotational moulding process. Following computer modelling, an industrial scale microwave oven was specifically designed, manufactured and attached to the drop-arm of a convention rotational moulding machine where extensive moulding trials were carried out. The design and development of the microwave oven and test mould, together with the savings in terms of energy efficiency and mould heating rate that were achieved are discussed.

Durability and performance of membranes under alternating relative humidity conditions are very important for fuel cells in automobile applications. This work proposed a wet/dry (W/D) cycle test and studied the effect of W/D cycles on the dimension and properties of polymer membranes. It was found that solution cast films shrunk stepwise in both machine and transverse directions when they underwent wet/dry cycles. The water swelling and water take-up of membranes are also a function of W/D cycles. Based on these results, one might use W/D cycling as a post-processing scheme to reduce the shrinking stress and water uptake of the membranes and thus extend the life of membranes.

The processing and mechanical properties of blown films prepared from thermoplastic corn starch (TPS) and polycaprolactone (PCL) has been studied. The aim was to determinate the influence of processing parameters on mechanical properties in order to establish the relationship between mechanical properties of the films, PCL concentration and processing. In addition, the influence of moisture content on mechanical properties during the first days of storage was also studied. The results showed that the effect of moisture absorbed during storage over the mechanical properties was not significant for blends that contained up to 60% PCL.