No abstract

No abstract

Polyolefin-organoclay nanocomposites containing a synthetic tetrasilisic fluoromica were prepared from metallocene-catalyzed and conventional Ziegler-Natta-catalyzed linear low-density polyethylenes (LLDPE) by means of melt-compounding. The effects of maleic-anhydride grafted compatibilizer (PE-g-MA) level, clay concentration, and blending procedure were investigated and compared. Morphology and structural analysis using transmission electron microscopy (TEM) and X-ray diffraction (XRD) suggested the clay exfoliation was more intense in the metallocene LLDPE matrix, conceivably because of the controlled short-chain branching and viscosity effects. When exfoliated, these silicate sheets were shown to restrict the lamellar crystallization, as seen by the decrease in crystallinity using differential scanning calorimetry analysis (DSC). The dynamic mechanical thermal analysis (DMTA) study suggested that the three ␣, ␤, and ␥-relaxations of the LLDPE were affected by polymer chain branching and clay exfoliation level.

1. A 1H-n.m.r. method was used to measure concentrations of valine, alanine, lactate, acetate, hyaluronan and lipids in synovial fluid obtained, during the normal course of examination from the knee joints of patients attending rheumatology and orthopaedic clinics. Fluid was available from 16 patients with osteoarthritis, 18 patients with rheumatoid arthritis, four patients with meniscal tear and one patient each with systemic lupus erythematosis, mono-arthritis, synovitis and loose bodies. Four normal specimens were obtained for comparison. 2. Valine, alanine and acetate levels all showed a normal Gaussian distribution, reflecting the distributions within the serum of the sample population. 3. Lactate concentrations divided into two distinct patterns. At concentrations below 2.5 mmol/l the lactate levels showed a Gaussian distribution, reflecting the distribution in normal serum. The normal synovial fluid specimens belong to this distribution. Above 2.5-3.0 mmol/l, lactate levels were asymmetric in distribution with a long tail at higher concentrations. These high levels of lactate can be explained by the generation of lactate through anaerobic metabolism within the synovial cavity. This metabolic process is triggered by a general inflammatory condition such as in rheumatoid arthritis. 4. The distribution of n.m.r.-observable lipid concentrations in rheumatoid arthritis and osteoarthritis each shows a normal distribution and the mean concentration is significantly higher in rheumatoid arthritis. 5. An increased n.m.r.-observable hyaluronan concentration is associated with an inflammatory situation. 6. It is concluded that raised levels of lactate and n.m.r.-observable hyaluronan and lipids are useful markers to aid the clinical distinction between rheumatoid arthritis and osteoarthritis.(ABSTRACT TRUNCATED AT 250 WORDS)

A range of LLDPE films with polyisobutylene (PIB) content from 2-8% was manufactured using a Killion blown film extrusion system and a cast film extrusion system. The films were aged at 25, 35 and 45 C for up to 28 days, to enable tack (cling) development. The results show that tack, in both blown and cast films, improved significantly with ageing at increased storage temperatures and at higher film blow up ratios. DSC analysis showed only a slight decrease in film crystallinity with increasing PIB concentration. The film tensile modulus, elongation and tear properties in both MD and TD were not significantly affected by an increase in PIB concentration.