SPE Library

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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Conference Proceedings

The Glass Transition Temperature Versus the Fictive Temperature

Prashanth Badrinarayanan, Wei Zheng, Sindee L. Simon, May 2006

It is well known that both the glass transition temperature (Tg) and the limiting fictive temperature (Tf') depend on the cooling rate. However, a comparison of the values of Tg and Tf' as a function of cooling rate has not previously been performed. In this work we have performed this comparison for a polystyrene sample using both capillary dilatometry and differential scanning calorimetry. The results from both techniques indicate that both Tg and Tf' have almost the same dependence on the cooling rate. However, Tf' is systematically lower than Tg presumably due to relaxation that occurs on heating.

Enthalpy Recovery: Do Materials Reach the Equilibrium Line?

Qingxiu Li, Sindee L. Simon, May 2006

Glasses are inherently non-equilibrium materials, and consequently, their properties evolve toward equilibrium in a process known as structural recovery or physical aging. Recently, several authors have suggested that the equilibrium liquid line is not reached even when properties have ceased to evolve. In this work, we present measurements of the enthalpy recovery of polystyrene at temperatures ranging from the vicinity of glass transition temperature to 10°C below Tg (90°C), for aging times up to 200 days. The results are analyzed in the context of the TNM model of structural recovery. In addition, we analyze data in the literature to determine whether enthalpy recovery ceases prior to the material reaching the equilibrium liquid line obtained by extrapolation of the liquid line above Tg. The results suggest that, in fact, the liquid enthalpy line is reached at temperatures below Tg when equilibrium is reached, i.e., when properties cease to evolve.

The Challenge of Teaching Blow Molding in a University Setting

Jonathan Meckley, May 2006

Teaching blow molding at the university level can be quite a challenge. Most universities with a plastics program focus on injection molding, as it represents the vast majority of the plastics industry. When blow molding is taught, it is usually buried within a course on other non-injection molding processes. The challenge is to bring together trained faculty, modern equipment (machines), challenging blow molding courses, a variety of training supplies (resin, molds, auxiliary equipment, …), and industrial support. Only then will there will be highly skilled students with blow molding knowledge and internship experience that are ready to make a positive impact in their field.

Morphology and Thermal Properties of In-Situ Composites

K. Jayanarayanan, A. Venkateshwar, Kuruvilla Joseph, Sabu Thomas, May 2006

Melt blending of polypropylene (PP) and poly (ethylene terephthalate) (PET) was carried out in a single screw extruder. The extruded blend was continuously drawn using an on line stretching equipment at different stretch ratios .The stretched blend was injection moulded to obtain an in-situ composite where PET microfibrils are randomly distributed in an isotropic PP matrix. The morphology of the blend was studied at the different stages of the composite preparation at different stretch ratios. It was found that the fibril diameter decreased as the stretch ratio increases. The thermal characterization of the stretched blend indicated that the PET phase act as nucleating agent for the crystallization of PP.

Unique Material Properties and Potential Applications of Novel High Performance Olefin Elastomers

Seema V. Karande, Y. Wilson Cheung, Charles F. Diehl, Michael J. Levinson, May 2006

Polyolefin elastomers are one of the fastest growing product families within elastomers markets. One of the largest usages of polyolefin elastomers is thermoplastic elastomer (TPE) compounds replacing styrenic based TPEs, flexible PVC, TPVs and thermoset rubbers. Recent advancements in polyolefin synthesis have given rise to novel high performance olefin elastomers. Structure-property relationships and markets/applications of these novel high performance olefin elastomers will be discussed in this paper.

The Development of a New Generation of Novel High Performance Olefin Elastomers: From Molecular Design to Market Development

Kurt W. Swogger, Edmund M. Carnahan, Wendy D. Hoenig, Anthony R. Frencham, May 2006

The polyolefins industry has had a long history of new product introductions brought about through technological developments, and the pace of these developments has accelerated in the last 20 years. This has been a period of breakthrough discoveries, from advanced Ziegler-Natta catalyst technology, through metallocene catalysis in the 1990’s, and more recently with the development of post-metallocene technology. With each of these new technology developments, more control of the polymer structures were achieved by the product designers allowing new, high value products to be produced. For example, in the 1990’s, metallocene technology allowed the control of polymer composition distributions and long chain branching.Today, at The Dow Chemical Company, a new generation of post-metallocene technology has been developed. This technology has allowed a more precise control of the polymer microstructure and has resulted in the making of novel, high performance olefin elastomers. This new capability allows the product designer to use molecular architecture approaches to further refine new products for its customers to rapidly capture market development needs. In this paper, the authors will discuss an on-going research effort at The Dow Chemical Company in using molecular architecture approaches to advance polyolefins product development and the use of the Speed Based1 market development approaches to provide new products for Dow’s customers to capture new markets.

The Physical Property Advantages Gained when Alloying/Blending of Polycarbonate with Polymethyl Methacrylate

J.P. Ibar, T. Hicks, S. Morneau, May 2006

Blends of Polymethyl Methacrylate and Polycarbonate (20/80 & 50/50) were made. This was accomplished using a Dual TekFlow Processor which has already demonstrated its ability not only to blend and intimately alloy polymers, but also offers the advantage to reduce the viscosity of the new blend by disentanglement. The result is usually a new blend, with properties closer to a theoretical mix, i.e. with a more predictable performance level than what has been possible by more conventional methods of blend preparation. Rheological and thermal testing shows that the blends have very little degradation and about 40% disentanglement, meaning an improved fluidity by 40% when compared to the compounded contribution of the individual components. The 20/80 PC/PMMA blends look white, extremely well dispersed, and could be mistaken, at first glance, with Polypropylene. Injection molded specimens were made for the blends and both virgin resins, which allowed for investigation of their comparative tensile, flexural, impact and thermal properties. Mechanical test results indicate that the properties of the 20/80 PC/PMMA blend are slightly better than the Virgin PMMA, whereas the 50/50 PC/PMMA blend has intermediary properties compared to both resins.

α- and β-Polypropylenes: The Effects of Processing on Final Properties

Roman Cermák, Martin Obadal, Veronika Habrová, Lubomír Benícek, May 2006

The study directs attention towards different effects of mould temperature and holding pressure on the tensile properties of injection-moulded neat and ?-nucleated polypropylenes. A commercial-grade of polypropylene was modified with a ?-nucleator. From both the original and ?- nucleated materials, tensile test specimens were injection-moulded. Stress-strain measurements performed at room temperature revealed that the effects on the tensile characteristics of both materials are more pronounced within mould temperature changes, compared with those of holding pressure.