Isamu Sekiguchi

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.

Dynamic viscoelastic properties of long organic fibre reinforced polypropylene in molten state

This paper deals with the dynamic viscoelastic properties of long organic fibre (aramid fibre (KF), polyvinyl alcohol fibre (VF) and polyamide fibre (PA6)) reinforced polypropylene in the molten state. Long organic fibres mixed with polypropylene fibres by an apparatus called a “fibre separating and flying machine″ were compression moulded into 3mm thick composites. Dynamic viscoelastic properties of these composites were measured in the molten state using a rotational parallel plate rheometer. It was found that the dependence of angular frequency on storage modulus, G′, for long organic fibre reinforced polypropylene is different from that of volume fraction of fibre, Vf and the relationships depend on the characteristics of the reinforcing organic fibres. The slope of the dynamic viscosity, η′ vs. angular frequency, ω curves increases gradually up to 45 degrees with increasing Vf. Influence of fibre content on dynamic viscoelastic properties depends on the organic fibre used. For low fibre content, G′ increases with increasing Vf in the same way as η′. However, the opposite trend is observed for high fibre content composites. It can be deduced that there is an apparent yield from the relations between complex viscosity, η* and complex modulus, G*. The yield value, G*y increases gradually with increasing fibre content and approaches a fixed value. All of the long organic fibre reinforced polypropylenes studied here are more sensitive to temperature than inorganic fibre reinforced composites.

Rheological properties of aminosilane surface treated short glass fibre reinforced polypropylenes. Part 1: Steady shear and oscillatory flow properties in molten state

The effect of surface treatment on the rheological properties of 20 and 40 wt.% short glass fibre reinforced polypropylenes (GF/PP) and of the same composites containing maleic anhydride modified polypropylene (GF/mPP/PP) were investigated. Glass fibres were surface-treated by aminosilane coupling agent (ASC, γ-aminopropyltriethoxysilane). Steady state shear and dynamic properties in the molten state were measured using a cone and plate type rotational viscometer. Surface treatment increased the rheological properties of the molten composites. This trend was more pronounced for composites containing modified PP. In the case of the GF/PP materials the increase was monotonous for all measured functions, while in the case of the GF/mPP/PP ones, the parameters representing elasticity showed peaks at 0.5 wt.% ASC. The Cox-Merz empirical law was found to be applicable to untreated GF/PP and GF/mPP/PP composites at low shear rates (angular frequencies), where the materials showed Newtonian plateaux. As for ASC surface treated materials, GF/mPP/PP followed the same trend. On the other hand, GF/PP exhibited a higher complex viscosity than the steady state shear one over the whole range of angular frequencies (shear rate) covered by the experiments. Surface treatment enhanced apparent yield stress, as did increasing the glass fibre content. The effect of the latter was more pronounced in the case of the GF/mPP/PP series. The viscosities of the re-mixed composites became lower than those of the original ones, and the difference between untreated and ASC treated systems was detectable only in the case of the complex viscosity of the GF/mPP/PP sample.

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.

The Effects of Carbon Fibre and PTFE Powder upon the Friction, the Wear and the Value of Limiting pv of Polyacetal

Two kinds of fillers, such as carbon fibre and PTFE powder, were used for the present study of their effects on the friction etc. of polyacetal.The contents of those fillers are 5, 10 and 25%, and length of carbon fibre are 1, 3 and 5mm, respectively.The friction and wear tests were carried out by using the Suzuki type friction tester and Itos sliding wear tester.The results obtained are as follows;(1) The kinetic frictional coefficient of polyacetal decreases with content of fillers, such as PTFE powder and carbon fibre.(2) The sliding wear amount of polyacetal containing PTFE powder is about 0.5∼0.7 times as much as that of unfilled polyacetal.(3) The value of limiting pv of polyacetal containing the fillers increases with the increase of the contents of both fillers, PTFE powder and carbon fibre, and with that of length of carbon fibre.The pv value of polyacetal containing PTFE powder is about 1.2∼2.2 times as much as that of unfilled polyacetal, and that containing carbon fibre is about 1.1∼1.6 times as much as that of unfilled polyacetal.