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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Effect of Length on the Alignment of Cellulose Microfibrils: A Small Angle Neutron Scattering Study
Cellulose microfibrils obtained by the acid hydrolysis of cellulose fibers were aligned in magnetic and shear fields. Small angle neutron scattering, SANS, was used to describe the effect of particle size on alignment. In a 2 Telsa magnetic field, aqueous suspensions of microfibrils exhibit enhanced cholesteric ordering; i.e. the entire sample becomes aligned in a helicoidal, chiral nematic arrangement with the chiral nematic axis aligned in the field direction. In a shear field, cellulose microfibrils align in a simple nematic arrangement, with no evidence of the chiral nematic (cholesteric) packing. The SANS interference peaks indicative of microfibril alignment sharpen with increasing shear rate regardless of the size of microfibrils. Length has a significant effect on the relaxation of enhanced ordering, with longer particles (280 nm in length) remaining remarkably ordered for many hours after cessation of shear, while shorter particles (<180 nm) lose their order within minutes.
Ultra High Molecular Weight Siloxane Additives in Polymers - Effects on Processing and Properties
Two new types of solid siloxane additives for plastics are described which give improved benefits compared to previous silicone additives. Ultra high molecular weight siloxanes are used in the new additives; traditional silicone plastic additives have used much lower molecular weight silicones. The siloxane is converted into solid forms, either masterbatch pellets or powders, that are easy to feed, or mix, into plastics during compounding, extrusion, or injection molding. Ultra high molecular weight siloxanes can be compounded into masterbatch pellets at higher siloxane concentrations (50%) than previously possible. They impart improved processing, release, lower coefficient of friction, and broader performance latitude compared to conventional lower molecular weight silicones. A new functionalized UHMW siloxane has been developed which has been found to provide unique surface segregation characteristics. Ultra high molecular weight siloxanes have been formulated into powders that can also act as processing aids and mechanical property modifiers. This paper will use polyolefins as a model. However, many of the effects shown in polyolefins have also been seen in other resin systems.
Dyes in PET: A Look at FDA Compliance Issues
The use of articles in food-contact applications involves both regulatory and scientific considerations where establishing the status of the individual product ingredients or components under the laws and regulations administered by the Food and Drug Administration (FDA) is required. This paper will focus on these considerations by discussing the definition of food additive, FDA's regulatory framework for substances used in food contact articles, and general requirements for testing the materials to establish their appropriate FDA status. This paper will also present a general overview of the data necessary for supporting a Food Additive Petition submitted to FDA to clear a new food-contact material or product such as dyes in PET.
Trends in Automotive Plastics
This briefing on trends in automotive plastics will delineate the differences in plastics application areas between North American and overseas markets. The key themes addressed include: • Although mass savings are widely thought to be a key driver in metal replacement by plastics, increasingly automakers are more interested in the contribution of plastics to styling, occupant safety and comfort, and functionality. • Plastics are increasingly specified for their design freedom. They make possible the consolidation of parts and consolidation of functions, minimizing manufacturing costs while maximizing function and value. • Competition among automotive plastics is relentless and intensifying, resulting in improved forecasted growth for some plastics at the expense of others. • Plastics application trends will be compared between North America and overseas in four sectors: Interiors, Exteriors, Under the Hood, and Chassis and Powertrain. • Greater attention is being given to polymer composites in the U. S. for exterior body panels and some structural applications, with minimal interest in other countries. • Finally, more progress is being made in the recycling of plastic manufacturing scrap than in the recycling of plastic parts/materials from scrap vehicles. This is so because manufacturers have control over process scrap, which improves recyclability and the value of recycled materials. The use of plastics in vehicles is steadily increasing. This trend is expected to continue. On average, current vehicles use about 113 Kg (250 Lbs) of plastics and that amount is estimated to grow to 137 kg (300 Lbs) per vehicle in the next ten years. Historically, vehicle weight savings has been a primary driver in replacing metals with plastics on vehicles. However, today styling, end-use functionality, and better manufacturing economics through parts consolidation are the key factors in choosing plastics to replace other materials in vehicle applications. In addition, fut
Investigation of the Crystallinity of a Hindered Phenolic Antioxidant by Differential Scanning Calorimetry
The effectiveness of polymer stabilizers has allowed polymers of all types to be used in increasingly critical applications. The performance of these additives is not only determined by the chemical efficacy of the molecule, but also by the ease with which it can be incorporated into the polymeric material in need of stabilization. Compounds which exist in several discrete crystalline or amorphous physical forms may behave in a profoundly different manner in terms of melting points and rates of dissolution.. Octadecyl 3-(3',5'-di-t-butyl-4'-hydroxy-phenyl) propionate (AO1) behaves in just this manner. Our investigation of the various crystal forms as well as an amorphous state demonstrate the care which needs to be taken to ensure that the optimum physical form is obtained.
Filled and Reinforced Aliphatic Polyketone Compounds
A major portion of engineering thermoplastic materials is utilized in the form of compounds containing a high loading of inorganic materials. The inorganic components may perform a variety of useful functions such as the reduction of compounds cost or the increase in stiffness, strength, dimensional stability, or heat resistance of the finished part. Aliphatic polyketones can be compounded with inorganic fillers and reinforcing agents resulting in benefits similar to those found in other thermoplastics. A discussion of the mechanical properties of compounds containing several types of fillers, classified according to chemical type and particle shape, will be presented.
Determining Apparent Melt Viscosity by Cavity Pressure
The online measurement of the viscosity of the polymer melt may contribute to the production of excellent products. The supervisory system of injection molding machines can only provide limited feedback on the processes in the cavity, therefore measuring the pressure in the mold contributes to the supervision of quality. The goal of our research is to gain more knowledge about the filling process and to determine the apparent viscosity of the material in the filling phase. For the research eight pressure sensors per cavity were built into an experimental specimen mold. Varying the wall thickness, the apparent viscosity was determined at different melt speeds. In the filling phase, non-isothermal and non-adiabatic flow were examined, they were considerably different from the environment of standard measuring equipment. The results were validated with a Göttfert capillary rheometer. They showed good agreement in a certain speed range and wall thickness when PP was used.
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