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Coatings of biomedical implant surfaces by a bioactive calcium phosphate film render bioactivity to the implant surface and shorten the healing time. In this present study, calcium metaphosphate (CMP) sol was synthesized by sol–gel method and coated onto the titanium alloys (Ti-6Al-4V). CMP sol was first synthesized by reacting Ca(NO3)24H2O (Sigma–Aldrich 99%, USA) with (OC2H5)3P (Fluka 97%, Japan) in methyl alcohol. A stoichiometric Ca/P ratio of 0.5 was obtained by varying the amounts of the reactants. Sol was then coated on Ti-6Al-4V substrates by spin coating. The coated-specimens were then dried at 70 °C for 24 h, followed by a heat treatment at 650 °C for 1 h. Structural and chemical properties of the coatings were evaluated using XRD, SEM, and EPMA. The dissolution property of the coated-CMP layer was investigated by immersing the samples in the simulated body fluid (SBF) for 1, 3, 7 and 21 days. The concentration of Ca2+ released was measured using ICP. After heat treatment, SEM indicated a smooth and uniform CMP layer, with CMP grains of approximately 100 nm. The CMP phase was identified with δ-CMP (JCPDS #9-363). After immersion in SBF, coatings were observed to be roughened and porous. The concentration of Ca2+ in SBF was observed to increase over time, indicating continuous dissolution. The presence of titanium oxide phosphate compounds were also observed on CMP surfaces after immersion. It was thus concluded that the ability to control coating properties as well as the need for low heat treatment temperature offers advance for the use of CMP coating by sol–gel process on Ti-6Al-4V implant surfaces.

Crack growth characteristics of rubbery materials are an important factor determining the strength and durability of the materials. It is necessary to define the means of measuring the fatigue crack growth rate of rubbery materials. In this paper, a test method is introduced using a newly designed test machine. Measurements were made in order to characterize the fatigue crack growth behavior under repeated load expressed as a crack growth rate, i.e. crack length per cycle, as a function of the tearing energy, determined by a broad range of the strain energy density in a test piece of pure shear geometry. Measurements were also made to observe the effects of test temperature and loading frequency. A high speed CCD camera is utilized to allow in situ measurements following the path of the crack growth simultaneously. The power law dependency between crack growth rate and tearing energy was confirmed by the new test methodology. Comparison of the fatigue crack growth behavior between NR and SBR rubber compounds was made, and the exponent α values of the NR compound were found to be, in general, lower than those of the SBR compound, indicating that the NR compound is more resistant to fatigue crack growth than the SBR compound.

In this study, the geometry of the tyre cord adhesion test (TCAT) was used to evaluate the adhesion strength between rubber and fibre. The activation energy (ΔE) of rubber compound used in this study was 72.43 kJ mol−1 and the difference of cure state between the inside and outside regions of the TCAT specimen with curing time was elucidated using the value of ΔE. The difference in cure state between the inside and outside regions of the TCAT specimen corresponded to the effect of 5.06 min of curing time. The cure state of the inside region of the TCAT specimen greatly affected the final adhesion strength and the results were confirmed by additional experiments. It was concluded that optimum adhesion between rubber and cord could not be obtained in a TCAT specimen unless the additional curing time to reach the optimum cure state of the inside region of the TCAT specimen was taken into account. Copyright © 2004 Society of Chemical Industry

Preparation and characterization of weather resistant silicone/acrylic resin coatings were investigated. In order to prepare the weather resistant resin coatings, a silicone/acrylic resin (KLD) was first prepared by an addition polymerization reaction of monomers, including n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and 3-methacryloxypropyl-trimethoxysilane (MPTS). In the preparation of the silicone/acrylic resin, T g of the acrylic copolymer was fixed at 40°C and the contents of MPTS were varied to be 10, 20, and 30 wt%. The weather resistant silicone/acrylic resin coatings were then prepared by blending the synthesized silicone/acrylic resin and TiO 2 . The viscosity of the synthesized resin decreased with the content of MPTS, whereas the thermal stability at high temperature increased. The prepared coatings exhibited excellent adhesion to various substrates, and various physical properties of the coatings were satisfactory. The weatherability of the coatings was tested by three ways: outdoor exposure test, Sunshine Weather-Ometer (WOM), and Q-ultraviolet (QUV) accelerated weatherability tester. The gloss retention, yellowness index difference, color difference, and lightness index difference were improved at high MPTS concentration. The coatings containing 30 wt% MPTS have especially good weather resistant properties.

Pyrophosphoric lactone-modified polyester containing two phosphorous functional groups in one structural unit of base resin was synthesized to prepare a nontoxic, reactive flame-retardant coatings. Then, the pyrophosphoric lactone-modified polyester was cured at room temperature with isocyanate and isophorone diisocyanate (IPDI)–isocyanurate to get a two-component polyurethane flame-retardant coatings (TAPPU). Comparing the physical properties of the films of TAPPU with the film of nonflame-retardant coatings, no deterioration of physical properties was observed with the incorporation of a flame-retarding component into the resin. Three kinds of flame retarding tests were conducted, including the 45° Meckel burner method, limiting oxygen index method (LOI method), and oxygen combustion method with Cone calorimeter. It was observed that the char lengths were 3.1∼4.5 cm and LOI values were 27∼30%. These results indicate that the prepared coatings are good flame-retardant ones. It was also found that the flame retardancy of those coatings was increased with the contents of phosphorous. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2316–2327, 2001

Long fiber molding materials are expected to play an important role in the near future. This paper describes a series of experiments performed to examine properties of ternary blends containing glass fiber (GF), polyamide (PA), and polypropylene (PP). The continuous glass fiber was impregnated with one of the blend constituent polymers by our specially designed impregnation apparatus and cut into chips of 6 mm length. These chips and the other polymer were used to produce various testing specimens in a twin screw extruder or in injection molding machine. The results indicated that the effect of fiber addition on the mechanical and rheological properties is clearly dependent on the order of impregnation process. In the blends containing the GF/PA + PP, the GFs are preferentially encapsulated with PA, and therefore the mechanical properties are superior to the blends with the GF/PP + PA in which the PP phase is located surrounding the GFs. This improved wetting of fibers by sequential impregnation not only resulted in better properties but also protected the fibers from shear action of the screw, thereby allowing significant increase in average fiber length to be achieved in the injection molding process.

Two-component polyurethane flame retardant coatings were prepared using phosphorus-containing lactone modified polyesters (PLMPs) and polyisocyanate. PLMPs were synthesized by poly-condensation of dimethyl phenylphosphonate, a flame retardant component with polycaprolactone, adipic acid, and trimethylolpropane. PLMPs were prepared with dimethyl phenylphosphonate content from 10 to 20 wt%. It was found that various physical properties of these new flame retardant coatings were comparable to non-flame retardant coatings. The flammability of coatings depends strongly on the dimethyl phenylphosphonate content in PLMP. Coatings with 20 wt% dimethyl phenylphosphonate content did not burn in the vertical burning test.