No abstract available

[en] A series of radiation-curable waterborne polyurethane dispersion was synthesized with two different NCO/OH ratios of 1.5 and 2.0. The polyurethane prepolymer was synthesized by reacting polypropylene glycol (MW=2000) with isophorone diisocyanate to produce -NCO end-capped polyurethane prepolymer. The prepolymer chain was then terminated with hydroxyethyl acrylate and dispersed with deionized water to produce polyurethane acrylate (PUA) dispersion. The PUA dispersions were mixed with two types of photoinitiators, Irgacure 500 and Darocur 1173, and cured under a medium pressure mercury ultraviolet lamp with a wavelength of 365 nm to produce PUA films. The effects of NCO/OH ratios and types of photoinitiators on the properties of PUA dispersion and PUA film were studied. Both dispersions of NCO/OH ratio 1.5 and 2.0 shows similar properties with a solid content of 40%, pH at around 7, and good dispersion stability with a zeta potential of NCO/OH ratio 1.5 at -60.9 while NCO/OH ratio 2.0 at -48.78. Only the viscosity of the dispersions displayed changes as it increased with the increasing NCO/OH ratio. Meanwhile, the curing speed of PUA dispersion with Irgacure 500 is better than Darocur 1173 at a low film thickness of 50um at 5 passes, however, as the thickness of the PUA film increased to 100um, the curing speed for all the dispersions became similar, at 9 passes, regardless of NCO/OH ratio or type of photoinitiators. Pendulum hardness test revealed that the type of photoinitiators does not affect the film hardness, the PUA film hardness, however, was affected by NCO/OH ratio, as it increased with increment in the NCO/OH ratio. (author)

[en] Studies on the photoinitiating activity of polymeric photoinitiators capable of promoting the UV curing of monomers or oligomers formulations, have allowed a deeper knowledge of the properties of these derivatives, which appear to offer additional advantages with respect to the corresponding low molecular weight products presently employed in various applications

[en] Curing UV machines are used to strengthen polymer molecular structures using cross linking techniques. This machine has undergone major damage control. This caused the investigation work to be interrupted. As manufacturers could not provide technical support due to obsolete tools, efforts to upgrade and upgrade were made. (author)

[en] Published in summary form only

[en] Short communication

[en] Short communications only

[en] Jominy harden ability test data provides valuable information for heat treatment engineers and for the quality control purpose. Often handbook data of Jominy test for various steels is given either in form of a single curve or as a band. This band defines the level of uncertainty observed in the test results. No systematic study is reported in literature, which explores the statistical nature of this variability. In this paper, results of a systematic study conducted on three different types of steel are reported. Using this experimentally generated data following was explored: (a) Nature of distribution of hardness at a specified location on the Jominy bar. (b)-Nature of variation of this distribution and its parameters as function of location on the Jominy bar. (c) Probabilistic interpretation of hardness profile observed on the specimen and its implications to the heat treatment and quality control engineers. (author)

[en] The palm oil-based ultraviolet (UV)-curable films were subjected to an outdoor soil burial test to investigate the biodegradation under natural environment. The films were burial in the soil experiment plot at the Nuclear Malaysia's Dengkil complex which is near the BTS building at block 42. Biodegradation tests are more specific to burial film in soil experiments for 12 months under natural conditions. The biodegradability of palm oil resin based UV-curable films were investigated and compared with the petrochemical resin based film. The films properties were compared with respect to properties of the film morphology and the film weight loss which are analyzed using the scanning electron microscope (SEM), an optical microscope and the weight loss of film calculation. These findings suggested that the palm oil-based UV-curable films show quite satisfactory biodegradation levels. (author)

[en] Radiation vulcanization of natural rubber latex (RVNRL) can be used to make large quantities of specially stabilized latex. It is possible to obtain RVNRL films of tensile strength over 25 MPa. The films could be either coagulant dipped or cast. It is very important to determine the correct radiation dose which gives the maximum tensile strength. Cross linking density or prevulcanized relax modulus (PRM) at 100% is a reliable property to control the prevulcanization