The location of hydroxyl functionality was investigated for thermosetting acrylic latexes. Large and small latex particles
with and without hydroxyl functionality were also synthesized and characterized. Large and small latex particles with and
without hydroxyl functionality were blended together, and the latexes were crosslinked. The location of hydroxyl groups in
the small or large latex particles had an effect upon the thermomechanical properties and hence on the ultimate performance
of the crosslinked latexes. The packing of the large and small latexes was dependent on small-to-large particle ratio, and
in addition had an effect upon the speed of film formation. The higher concentration of hydroxyl groups in the small latex
particles contributed more to the tensile properties of the latexes than the functionality of the large particles.
[Show abstract][Hide abstract] ABSTRACT: The current engineering program accreditation criteria requires an effective program outcome (PO) assessment procedure along with well documented results, a complete description of the evaluation process that involves extensive participation of the faculty members. To achieve all these, an effective method to estimate students’ performance as well as the effectiveness of the program outcomes (PO) is required. As such, the direct assessment method has been identified and deemed suitable to directly assessed specific students’ knowledge during examination or through skills observation. Specifically, this work reports the effort made by the Department of Electrical, Electronics and System, (EESE), Universiti Kebangsaan Malaysia (UKM) to implement the direct assessment method to measure the PO achievement of its students. This is in line with the EESE Dept.’s continuous quality improvement (CQI) practice to improve its PO assessment method before the next visit by the Accreditation Council in 2011. To do so, the assessment results from each semester of the academic sessions 2008/2009 and 2009/2010 are analysed to produce the annual PO. Measurement of PO achievement is carried out on selected sampled courses. In selecting the courses for the assessment, at least two courses from each academic year that are offered in the two different semesters are selected. Since the academic program is a 4 year program, 8 courses need to be selected for the purpose. Accordingly, this paper is written to describe the assessment method used to measure the PO via direct assessment of the course outcomes (Cos) as an improvement to previous practice where the COs were assessed indirectly using survey and examination results. The direct assessment results showed that the average PO attainment for both academic session 2008/2009 and 2009/2010 are greater than 3.0 and fulfils the benchmark value set by the department. Nevertheless, the Dept. is still putting up an effort to improve the assessment method in order to find the best method to directly assess both COs and POs simultaneously.
Procedia - Social and Behavioral Sciences 12/2011; 18:49-55. DOI:10.1016/j.sbspro.2011.05.008
[Show abstract][Hide abstract] ABSTRACT: To develop new high performance water based acrylic coatings a core of basic knowledge is needed, covering phenomena going from penetration into wood to morphology of the coated film. An overview of the issues will be presented in the paper correlating the different problems that the development of a novel coating might present. The paper is focused in particular on one component acrylic latexes, for their ease of application, and nanolatexes, which use could contribute to new improvements. We present new preliminary results of experimental investigations where some of the main issues are addressed.
[Show abstract][Hide abstract] ABSTRACT: 2-Hydroxyethyl methacrylate (HEMA)-rich latex is synthesized via a semibatch monomer-starved emulsion polymerization process. Six emulsion polymerizations, containing 0-40 mol% HEMA in monomer composition, are synthesized and compared. Calculations of mass balances are made in order to predict final particle size and particle size development during the course of polymerization. Average particle sizes obtained by dynamic light scattering (DLS) are compared to ultrasound acoustic attenuation spectroscopy (UAAS) and transmission electron microscopy (TEM). The influence of HEMA on polymerization on the onset of secondary nucleation is evaluated using each technique. The DLS, TEM, and UAAS secondary nucleation data are compared to physical latex blends of small and large particles. The blend data are consistent with the secondary nucleation data. Additionally, conductivity and surface tension are monitored. TEM, atomic force microscope (AFM), and UAAS are found to be more appropriate methods than the widely used DLS for particle size and particle size distribution characterization in this system. Increasing HEMA content to 20 mol% results in formation of significant amount of secondary particles via proposed homogeneous nucleation of HEMA-rich oligomers.
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