Cary N. Marzinsky

Interlamellar failure at transcrystalline interfaces in glass/polypropylene composites

Abstract Transcrystalline microstructures are normally not observed at the interface between E-glass fibers and an isotactic polypropylene matrix, unless mechanical translation is applied to the fiber while it is in the supercooled polymer melt. We demonstrate here that transcrystallinity can form at the surface of E-glass fibers if appropriate nucleating agents are used to coat the fibers. These agents can nucleate either the α (monoclinic) or β (hexagonal) crystal forms of polypropylene. Single-fiber composite experiments were performed to assess the effect of transcrystallinity on matrix deformation. The preliminary results presented here reveal the occurrence of a previously unreported damage mechanism by which interlamellar fractures form preferentially at the interface well before any bulk matrix damage occurs. The density of this damage zone is higher in transcrystallinity of the β crystal form than of the α form, although it was found that in the α form the damage can propagate into the matrix. The occurrence of this damage mechanism suggests that toughness increases may potentially be obtained by careful design of the interfacial transcrystalline region in E-glass/polypropylene composites.

Morphology and Damage Mechanisms of the Transcrystalline Interphase in Polypropylene

Abstract By coating glass fibers with the appropriate nucleating agent, transcrystallinity can be generated in polypropylene/glass composities. Transcrystallinity can consist either of the alpha (monoclinic) or beta (hexagonal) crystal structure. Through the use of directional solidification, the transcrystalline morphology can be duplicated in polypropylene films on a level large enough for mechanical and morphological study. Permanganic etching and subsequent electron microscopy reveals that lamellar orientation in alpha transcrystallinity differs significantly from the beta form. Alpha transcrystallinity consists of lamellae which are edge-on relative to the polypropylene film thickness, while beta transcrystallinity consists of lamellae which are primarily flat-on. This difference in morphology results in significant variations in mechanical properties and damage mechanisms.

Applications of optical fiber sensors in the oil refining and petrochemical industries

Optical fiber distributed sensing technologies, consisting of many sensors in one single fiber, present unique and cost-effective solutions for the oil refining and petrochemical industries to optimize process operations and improve reliability and safety. In addition, optical fiber sensors do not require electrical power at the sensing locations, reducing the need for explosion-proof electronic packaging. This paper reviews state-of-the-art commercial optical fiber distributed temperature and strain sensing technologies, and presents challenges and opportunities for these technologies in the oil refining and petrochemical industries. Attention is drawn to the fundamental understanding of optical fiber materials and development of reliable sensor protection and installation methods for harsh environments.