Yasushi Oyanagi

Viscous properties of calcium carbonate filled polymer melts

SummaryThe viscous properties of calcium carbonate filled polyethylene and polystyrene melts were examined. The relative vircosityηr defined in the previous paper gave an asymtptotic value(ηr)l in the range of the shear stress below 105 dyne/cm2.(ηr)l of the calcium carbonate filled system was higher than that of the glass beads or glass balloons filled system at the same volume fraction of the fillerφ. Maron-Pierce equation withφ0 = 0.44 was able to approximate the(ηr)l — φ relationship. However, it was deduced here that the high value of(ηr)l of calcium carbonyl filled system was due to the apparent increase ofφ and this increase was attributed to the fixed polymer layer formed on the powder particle. By assuming the particle as a sphere with a diameter of 2 µm, the thickness of the fixed polymer layer was estimated as about 0.17 µm. The yield stress estimated from the Cassons plots increased exponentially withφ.ZusammenfassungEs wurden die viskosen Eigenschaften von Polyäthylen-und Polystyrol-Schmelzen untersucht, die mit Kalziumkarbonat-Teilchen gefüllt waren. Für die relative Viskositätηr, wie sie in einer vorangegangenen Veröffentlichung definiert worden war, ergab sich bei Schubspannungen unterhalb 105 dyn/cm2 ein asymptotischer Wert(ηr)l. Dieser war bei den mit Kalziumkarbonat gefüllten Schmelzen höher als bei Schmelzen, die bis zur gleichen Volumenkonzentrationφ mit Glaskugeln oder Glasballons gefüllt waren. Die (ηr)l —φ-Abhängigkeit ließ sich durch eine Gleichung nachMaron und Pierce mitφ0 = 0,44 beschreiben. Es wurde jedoch geschlossen, daß der hohe(ηr)l-Wert der mit Kalziumkarbonat gefüllten Schmelzen auf eine scheinbare Zunahme vonφ zurückzuführen ist, verursacht durch eine feste Polymerschicht auf der Teilchenoberfläche. Unter Annahme kugelförmiger Teilchen mit einem Durchmesser von 2 µm ließ sich die zugeordnete Schichtdicke zu 0,17 µm abschätzen. Die mittels der Casson-Beziehung geschätzte Fließspannung ergab eine exponentielleφ-Abhängigkeit.

Tribological properties of COPNA resin

Abstract In this study, the effects of the addition of several solid lubricants on the hardness, bending strength, impact strength and tribological properties of COPNA (SK) resin were evaluated. The solid lubricants were polytetrafluoroethylene (PTFE), molybdenum disulphide (MoS 2 ) and graphite (GP). The results are summarized as follows. 1. (1) The bending strengths for PTFE (20%), MoS 2 (20 and 30%) and GP-filled SK composites fall between 53 and 82 MPa, which is 1.8–2.9 times as much as that of pure SK resin. The impact strength for PTFE-, MoS 2 and GP-filled SK composites fall between 0.12 and 0.49 J cm −2 , which is two to eight times that of SK itself. 2. (2) The limiting pv values for PTFE or GP-filled SK composites are 2.8–4.8 MPa m s −1 , which is 1.4–2.2 times that of SK resin itself. 3. (3) The wear rates of PTFE-, MoS 2- , or GP-filled SK composites are 0.2–3.4 × 10 −4 mm 3 N −1 m −1 . GP is the most effective filler for reducing the wear rate of these three solid lubricants. 4. (4) The frictional coefficients of these SK composites fall between 0.135 and 0.237, which is 0.35–0.8 times that of SK resin itself.

Pressure Effects on Rheological Behavior of Melt Polymers – A Discussion in Relation to Polymer Processing

Abstract Polymers have large bulk compressibility in the molten state /1/ and their rheological properties are largely affected by pressure applied in polymer processing. The volumetric strain induced by pressure consists of instantaneous and retarded elastic strains, both of which are proportional to pressure, and recover reversibly when pressure is removed. In many crystalline polymers, as observed by B. Maxwell for polyethylene, retarded elastic strain is large, and due mostly to pressure crystallization. This paper describes results of experimental studies relating pressure effects on rheological properties of melt polymers with polymer processing and bulk properties of products. The following items are discussed: pressure induced shear stress, analysis of local deformation pattern, critical shear stress for melt flow fracture, relationship between power law index and bulk compressibility, effects of hydrostatic pressure on melt flow behavior, pressure efficiency of injection molding, jetting phenomena, shrinkage in injection moldings, residual strain, and super-high-pressure injection molding process.

On some properties of COPNA resin

In this study, the effects of the addition of several solid lubricants on the hardness, bending stength, impact strength and tribological properties of COPNA SK resin were evaluated. The solid lubricants were polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS2) and graphite (GP).The results are summarized as follows;1) The bending strengths for PTFE (20%), MoS2 (20, 30%) and GP-filled SK composites fall between 53-82MPa, which is 1.8-2.9 times as much as that of neat SK resin.The impact strengths for PTFE, MoS2 and GP filled SK composites fall between 0.12-0.49J/cm2, which is 2-8 times as much as that of SK itself.2) The limiting pv values for PTFE or GP filled SK composites are 2.8-4.8MPa·m/s, which is 1.4-2.2 times as much as that of SK resin itself.3) The wear rates of PTFE, MoS2 or GP filled SK composites are 0.2-3.4×10-4mm3/N·m. GP is the most effective filler to reduce the wear rate among these three solid lubricants.4) The frictional coefficients of these SK composites fall between 0.135-0.237. which is 0.35-0.8 times as much as that of SK resin itself.