Brunel University London

About: Brunel University London is a education organization based out in London, United Kingdom. It is known for research contribution in the topics: Large Hadron Collider & Population. The organization has 10918 authors who have published 29515 publications receiving 893330 citations. The organization is also known as: Brunel & University of Brunel.

Processing and Physical Property Relationships in Injection-Molded Isotactic Polypropylene .2. Morphology and Crystallinity

Abstract: A preceding article referred to the processing of various grades of isotactic polypropylene (iPP) and propylene/ethylene copolymers by conventional and shear-controlled orientation injection molding (SCORIM), and considered the mechanical properties of the molded polymers in relation to the processing conditions applied. This article is principally concerned with the morphology and phase relationships that apply in injection-molded iPP. The γ-phase of isotactic polypropylene is reported to occur in moldings with pronounced molecular orientation. The presence of γ-phase in injection moldings is indicative of enhanced Young's modulus, and tensile strength provided that the melt has not been subjected to excessive deformation during processing. The common view that isotactic polypropylene exhibits only α- and β-phases in commercially produced moldings is challenged. SCORIM moldings contain less β-phase than conventional moldings, and exhibit greater overall crystallinity than moldings produced by conventional methods. The difference in the relative proportions of α-, β-, and γ-phases is marked and depends on processing conditions and the molding method. Shear-controlled orientation injection molding (SCORIM) results in more pronounced molecular orientation than conventional injection molding, which is consistent with the substantial increase in Young's modulus of moldings produced by SCORIM. The improved mechanical properties of iPP moldings is attributed to shish-kebab morphology developed by the action of shear to the solidifying melt. A new model is proposed for the oriented region morphology in iPP injection moldings based on the results presented in this article. © 1997 John Wiley & Sons, Inc.

Psychophysical and ergogenic effects of synchronous music during treadmill walking

Abstract: The present study examined the impact of motivational music and oudeterous (neutral in terms of motivational qualities) music on endurance and a range of psychophysical indices during a treadmill walking task. Experimental participants (N=30; mean age=20.5 years, SD=1.0 years) selected a program of either pop or rock tracks from artists identified in an earlier survey. They walked to exhaustion, starting at 75% maximal heart rate reserve, under conditions of motivational synchronous music, oudeterous synchronous music, and a no-music control. Dependent measures included time to exhaustion, ratings of perceived exertion (RPE), and in-task affect (both recorded at 2-min intervals), and exercise-induced feeling states. A one-way repeated measures ANOVA was used to analyze time to exhaustion data. Two-way repeated measures (Music Condition ? Trial Point) ANOVAs were used to analyze in-task measures, whereas a one-way repeated measures MANOVA was used to analyze the exercise-induced feeling states data. Results indicated that endurance was increased in both music conditions and that motivational music had a greater ergogenic effect than did oudeterous music (p .05) upon RPE or exercise-induced feeling states, although a moderate effect size was recorded for the latter (etap2=.09). The present results indicate that motivational synchronous music can elicit an ergogenic effect and enhance in-task affect during an exhaustive endurance task.