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.
Producing cellular wood-fiber/plastic composite (WPC) with physical blowing agents (PBA) offers unique advantages over chemical blowing agents (CBA). This paper compares the foaming behaviors of two environmentally benign PBAs, namely N2 and CO2, to help understand PBA-based foaming mechanisms in WPC. This understanding will help in making proper choices about PBAs and foam processing parameters.
A blend of two polycarbonate copolymers, high-heat poly(ester-carbonate) (PEC) and polycarbonate-polydimethylsiloxane copolymer (PC-PDMS) provided an opaque, pearlescent blend. However, when a transesterification catalyst was used, the blend becomes miscible and translucent/transparent. The high-heat, ductile (HHD) materials were analyzed for a range of properties including optics, rheology, heat performance, flame retardance, and mechanical properties. The hydrolytic stability of the HHD materials was also measured by comparing the ductility of the blends before and after autoclaving.
This paper investigates the extrusion foaming behaviors of Polyethyleneterephthalate (PET) blown with supercritical CO2. The evolution of the foam's morphology once it exited from the die was recorded using a CCD camera and also characterized by SEM. Microcellular PET foams can be prepared by optimizing the PET properties as well as the processing conditions.
The effect of shear on the temporal development of phase separation in thermotropic liquid crystalline polymer (LCP)/polycarbonate (PC) blends was examined. Experiments were performed using a polarized-light microscope, equipped with a shearing hot stage. Phase separation, with and without shear, in blends containing 50 wt % LCP were analyzed. The results showed that the speed and amount of phase separation increased when shear was applied.
To better understand the underlying mechanisms of immiscible blend polystyrene/poly (methyl methacrylate) (PS/PMMA) foaming, a simple bilayer representation is examined. Visual observation of batch foaming of this system is conducted and a quenching method is used to study foams with different bubble growth time. These help understand the effects of blend morphology on foaming in a more quantitative way.
Heterogeneous polymers represent an important class of plastics that comprise polymer blends, alloys, and fiber or mineral filled plastics. The rheology of these melts is dominated by the transient morphology that is produced during fabrication into finished products. Standard laboratory rheological tests do not take into account morphology. Combined measurements of a capillary viscometer and controlled stress rotational rheometer can provide a better understanding of the processing behavior of these complex rheological plastics
The topic of clusters has emerged as a crucial idea in competitiveness and economic development in the last years. This paper shows and discusses (basing on concrete plastic cluster in the Czech Republic) possible approaches to the cluster performance measurement. There are analyzed problems related to the performance measurement and suggested suitable performance measures. This case-study also shows the possibilities for mutual cooperation and ways in which the research results can be transferred into working practice.
The effects of degradation on the mechanical and aesthetic properties of injection-molded biodegradable polylactide (PLA) parts were studied. Standard tensile test specimens were molded from NatureWorks 3051D injection-molding grade PLA. Barrel residence time, machine nozzle temperature, and shear rate were varied during the injection-molding process. The resulting specimens were analyzed in a tensile testing machine. Tensile strength, tensile modulus and visual inspection were used to characterize the extent of degradation that occurred during each process.
Polypropylene pipe and fittings were selected for a high-purity, highly chlorinated water system in a medical research facility. In the first four years of operation, the system sustained an excessive number of leaks. This paper is an account of the investigation of the causes of those leaks.
For high doses, a DMA analysis of wood and composites revealed a change in lignin resulting in reduced Tg, and that electron scavenging from lignin's aromatic structure could hinder the cure. An investigation of purified cellulose revealed changes at higher doses in the physical response to moisture and thermal stability without a change in the degree of crystallinity as measured by wide-angle X-ray scattering (WAXS).
A preliminary account is given of issues involved in numerical simulation of water assisted injection molding (WAIM), extending techniques used previously for gas assisted molding. An industrial scale, instrumented process is used to guide and validate the simulations. Novel sensor technologies, including ultrasound, are used at process to monitor the position of the water bubble during filling, together with melt pressures and temperatures as well as the residual wall thickness.
Several processes currently exist that produce a thin-walled part with a fabric-covered surface. These processes, however, are limited by cost, low production volumes, and durability of the part. A new process is described here that produces a high-quality and durable, thin-walled part using low-cost mass production techniques.
The color and appearance of a formulation must be engineered just like any other desired thermal or mechanical property of the resin itself. The ability to achieve the desired color can be adversely affected by processing or the combination with modifiers and additives in the resin system. Even if colors can be achieved, other performance attributes such as UV stability, flammability or mechanical properties may be adversely affected as well. This paper looks at some of these color concerns.
It is widely recognized that molecular weight distribution (MWD) is an important factor affecting the rheological behavior of polymer solutions. In this contribution, the effects of MWD on the formation of electrospun polystyrene fibers in THF have been studied. The results are compared with the monodisperse system. The importance of chain entanglements attributed to high molecular weight component within the polydisperse system has been acknowledged. Concentrations for the incipient as well as stable fiber formation in a polydisperse system may be predicted.
The capability of using residual agave fibers from the tequila production process, to reinforce virgin, reprocessed or recycled polypropylene, is studied. Polypropylene composites were prepared with milled (65 mesh) agave fibers and Epolene E-43 in a twin screw extruder, varying the amount of fiber. Tensile, impact and dynamic tests, along with scanning electron microscopy observations were carried out. The importance of polymer-fiber interaction through the presence of the coupling agent is clearly shown.
The instantaneous melting rate of single screw extruders are primarily affected by the screw speed, barrel temperature and screw diameter. However, with all things being equal the overall melting capacity of the screw is controlled by the solids bed-barrel contact area. Three screws, a conventional, a barrier and a barrier-XLK design with variable melting areas are evaluated for overall melting capacity as defined by their specific output.
Selecting proper process settings is crucial in injection molding as part quality is greatly influenced by the process conditions. The locations of the injection gate need to be decided before the mold is made. Other processing variables can be adjusted during start up; however changing the gate location at a later stage involves great cost. In this work, we analyze the effect of gate location on process consistency for an automotive part, using a multivariable optimization method called Data Envelopment Analysis (DEA).
A common pigment used in many plastics application is titanium dioxide, TiO2. The pigment is a very effective light scattering inorganic oxide for the coloration and protection of plastic articles. TiO2 is also an insoluble material within a polymer matrix that has the ability to adsorb other materials within the matrix. Additionally, a TiO2 particle can catalyze the formation of chromophores from additive deactivation. This aper describes the adsorption behavior of several TiO2 materials compares the rate of chromophore formation in a polyethylene matrix compounded.
Ideal nucleating agents are expected to improve the cell morphology of plastics foams (i.e., higher cell densities, smaller cell size, and narrower cell size distribution) by providing heterogeneous nucleation sites. Surface geometry is one of the factors that govern the nucleating power of nucleating agents. Based on the computer simulation of a batch foaming process of polystyrene/carbon dioxide system, this paper indicates that nucleating agents having numerous crevices of small semi-conical angles, are most desirable for polymeric foaming processes.
The current coronary artery stent coating, styrene-bisobutylene- b-styrene copolymer,  has been researched and several problems arise when this coating is used. A alternative coating needs to be developed with several polymers forming from the main chain of the polymer. Several different bromination techniques have been researched to achieve the desired polymer to create the drug eluting coronary artery stent. This paper will describe the methods used.
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Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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