X-ray Diffraction Study of iPP/clay and iPP/TiO2 Composites Relating to Micromechanical Properties

Composites of isotactic polypropylene with various contents of white clay or titanium dioxide TiO2 were prepared by extrusion molding. The extruded composites were melt-pressed at two different temperatures, and,thereafter, either slowly cooled, or quenched to room temperatures. It is shown that the structure of all the samples, as revealed by wide-angle X-ray scattering and small-angle X-ray scattering (SAXS), depends on the processing conditions. The lack of SAXS maxima in the composites suggests that the presence of the microadditives hinders the stacking of iPP lamellae. Furthermore, the microindentation hardness H in the slowly cooled composites is influenced by the type and amount of the filler used. However, in the quenched samples H depends only on the amount of the filler used, and not on its type. In case of the quenched iPP/clay composites, the relationship between H and the Young’s modulus E is found to be H/E approx. equal to 0.12, in good agreement with Struik’s theoretical predictions of sigma e approx. equal to E/30, in consonance with results previously obtained for a series of polyethylene samples with different morphology.Peer reviewe

MaxFlow-MinCut Duality for a Paint Shop Problem

Motivated by an application in car manufacturing we consider the following problem: How can we synthesize a given word from restricted reservoirs of colored letters with a minimal number of color changes between adjacent letters? We focus on instances in which each letter occurs exactly twice, once in each of two given colors. In this case the problem turns out to be the dual of a MinCut problem for one point extensions of a certain class of regular matroids

Crystalline plasticity in isotactic polypropylene below and above the glass transition temperature

In-situ X-ray diffraction was applied to isotactic polypropylene with a high volume fraction of α-phase (α-iPP) while it has been compressed at temperatures below and above its glass transition temperature Tg. The diffraction patterns were evaluated by the Multi-reflection X-ray Profile Analysis (MXPA) method, revealing microstructural parameters such as the density of dislocations and the size of coherently scattering domains (CSD-size). A significant difference in the development of the dislocation density was found compared to compression at temperatures above Tg, pointing at a different plastic deformation mechanism at these temperatures. Based on the individual evolutions of the dislocation density and CSD-size observed as a function of compressive strain, suggestions for the deformation mechanisms occurring below and above Tg are made

Towards the Generation of Setup Matrices from Route Sheets and Feedback Data with Data Analytics

Part 8: Knowledge Based EngineeringInternational audienceThe function or department of production control in manufacturing companies deals with short-term scheduling of orders and the management of deviations during order execution. Depending on the equipment and characteristics of orders, sequence dependent setup times might occur. In these cases for companies that focus on high utilization of their assets due to long phases of ramp up and high energy costs, it might be optimal to choose sequences with minimal setup time times between orders. Identifying such sequences requires detailed and correct information regarding the specific setup times. With increasing product variety and shorter lot sizes, it becomes more difficult and rather time intense to determine these values manually. One approach is to analyse the relevant features of the orders described in the route sheets or recipes to find similarities in materials and required tools. This paper presents a methodology, which supports setup optimized sequencing for sequence dependent setup times through constructing the setup matrix from such route sheets with the use of data analytics