Design basis and hydrodynamic performance analysis of single-screw extruders. I - polymer flow behaviour

WOS: 000268149200002Purpose - The purpose of this paper is to investigate the hydrodynamic performance of a single-screw extruder with special reference to metering region. Design/methodology/approach - The hydrodynamic analysis of a single screw extruder is carried out by dimensional and non-dimensional parameters defining the polymer flow behaviour. The flow types formed in the extruder channel are defined and the relationship between the flow with the extruder geometry is examined. Findings - The theoretical model developed is capable of estimating the hydrodynamic behaviour of extruder metering region. With the model developed, extruder geometry and polymer flow rate under different operating conditions can be predicted. Originality/value - This paper offers a quick and easy opportunity to examine the hydrodynamic behaviour of extruder metering region. With the theoretical model developed, the behaviour of the flow in extruder can be modelled and estimated

Recesses along the posterior margin of the infrapatellar (Hoffa's) fat pad: prevalence and morphology on routine MR imaging of the knee

The objective is to evaluate the prevalence and morphology of recesses along the posterior margin of the infrapatellar fat pad on routine MR imaging of the knee. MR images of 213 knees in 204 consecutive individuals were evaluated with regard to the prevalence and morphology of recesses (a "suprahoffatic" recess close to the inferior border of the patella and the previously described "infrahoffatic" recess anterior to the inferior portion of the infrapatellar plica). The recesses were analyzed with regard to synovial effusion and the condition of the anterior cruciate ligament (ACL). Anatomic dissection was made in 29 knees in 16 cadavers to verify the presence of the suprahoffatic recess. The infrahoffatic recess was present in 45% of the knees and mostly linear in shape (44%). The suprahoffatic recess was detected in 71% of the knees (45% in cadavers). Very weak to moderate positive correlation was found between the synovial effusion or the condition of the ACL and the presence and dimensions of the recesses. An awareness of the recesses in the infrapatellar fat pad is important in order to distinguish between pathology and anatomic variants on routine MR imaging of the knee

Mechanical characterization of flocked fabric for automobile seat cover

In this study, the tensile and tearing properties of substrate, substrate with adhesive and flocked fabric were studied with developed regression model which explains the relationships between fabric forms and tensile and tearing strength of the flocked fabrics. Warp and weft tensile strengths of wet flocked fabric are generally higher than the warp and weft tensile strengths of dry flocked fabric due to the high wet properties of cotton yarn. Weft tensile elongation of the flocked fabric is generally higher than warp tensile elongation due to the higher crimp ratio of the flocked fabric in the weft direction. Warp and weft tearing strengths of wet form substrate with adhesive and flocked fabric are higher than those of dry forms of substrate with adhesive and flocked fabric. One of the reasons could be the decrease of inter-yarn frictional forces due to the lubrication effect of the wet form of acrylic adhesive in substrate with adhesive fabric. Generally, tearing strength of flocked fabric is low compared with substrate. It was concluded that the regression model used in this study could be viable and reliable tools and flocked fabric could be considered as an alternative seat cover material to use in automotive industry. © 2011 The Korean Fiber Society and Springer Netherlands