Comparison of a New Estolide Oxidative Stability Package

The rotating pressurized vessel oxidation test (RPVOT) was used in the analysis and determination of a new oxidative stability package (OSP) for a series of estolide based materials. Three antioxidants (BHT, two different alkylated diphenyl amines) were used in either 0.5 or 1.0 wt/wt%, in different ratios, and in conjunction with one another (hindered phenol/alkylated diphenyl amines or hindered phenol/mixed alkylated diphenyl amines). The estolide-based samples analyzed for their resistance to oxidation were two pure (distilled) estolides (oleic estolide 2-EH esters and coco-oleic estolide 2-EH esters), an estolide mixture that was analyzed straight from the reaction (coco-oleic estolide 2-EH esters with coco 2-EH esters) and finally the ester fraction from the estolide mixture (coco 2-EH esters). The coco estolide mixture and coco 2-EH esters had the best overall RPVOT times with 1.0% of the alkylated diphenyl amine, coco estolide mixture, 326 min, and coco 2-EH esters, 310 min. Coco estolides were expected to have an advantage over the simple oleic estolides due to the increase in saturation in the estolide. Unexpectedly, the two distilled estolides (oleic and coco) had very similar RPVOT max times with all the antioxidants, and were much higher than the other oxidative packages tested to date. In general, the alkylated diphenyl amine outperformed mixed alkylated diphenyl amines in the majority of the individual samples tested specially the coco 2-EH esters and distilled coco-oleic estolide 2-EH esters material at 1% OSP. Overall, a series of new antioxidants were tested and compared to other commercial products. A variety of physical properties of the four estolide based material were collected and compared to commercially acceptable material. Coco-oleic estolide 2-EH esters were formulated to have excellent pour points (−36 °C), were both oxidatively and hydrolytically stable (RPVOT, 310 min), with expected good biodegradability which should help commercialization. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Online video traffic modelling with wavelet transform

An online video traffic model based on the wavelet transform is proposed and evaluated. The key to the online model support is the removal of least significant wavelet components, within a coarse time resolution, as necessitated by a priori model parameter estimation. This, in turn is achieved through knowledge gained from the autocorrelation function of the base video traffic trace     

Investigation of the surface properties of polymeric soaps obtained by ring‐opening polymerization of epoxidized soybean oil

Epoxidized soybean oil (ESO) was converted to a polysoap (PESO) via a two‐step synthetic procedure of catalytic ring‐opening polymerization, followed by hydrolysis (HPESO) with a base. Various molecular weights of PESO and HPESO were prepared by varying the reaction temperature and/or catalyst concentration. In addition, the counter ion chemistry was varied by changing the base used for saponification. The PESO and HPESO products were carefully characterized and identified using a combination of FTIR, ¹H‐NMR, solid state ¹³C‐NMR, and GPC. The effect of HPESO polysoaps on the surface tension of water and the interfacial tension of water‐hexadecane was investigated as a function of HPESO concentration, molecular weight, and counter ion chemistry. HPESO polysoaps were effective at lowering the surface tension of water and the interfacial tension of water‐hexadecane and displayed minimum values in the range of 20–24 and 12–17 dyn/cm, respectively, at concentration of 200–250 μM. Water‐hexadecane interfacial tension was also calculated from measured surface tension data using the Antonoff, harmonic mean (HM), and geometric mean (GM) methods. Measured values agreed well with those calculated using the HM and GM methods, but not the Antonoff method. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Film-forming properties of estolides

Estolides are biobased materials obtained from the synthesis of ingredients derived from agricultural products. They are oligoesters obtained by the reaction of fatty acids and/or methyl esters with a double bond. By varying the chemistries of the starting materials and the reaction conditions, estolides of varying chemical structures (e.g., branching), and physical properties (e.g., mol wt, viscosity, pour point, cloud point) are obtained. Estolides have been found to have suitable properties for some lubrication applications. In this work, the effect of estolide physical/chemical variability on film thickness and pressure–viscosity coefficient (pvc) were examined. The results showed that estolides have lower pvc than the non-polar hydrocarbon PAO, but much higher than seed oils (e.g., soybean, jojoba, canola), which are used as feedstock in estolide synthesis. The film thickness and pvc properties of estolides were also found to be dependent on the structure (e.g., homo- versus co-oligomer) and purity of the estolide oils. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

CT-scanning and modelling of the capillary water uptake in aspen, oak and pine

This study utilises Computer Tomography (CT-scanning) to characterize the capillary water uptake in wood specimens. CT-scanning makes it possible to study the capillary rise of water as a function of height in wood specimens after a specific exposure time. The study has also included the development of a theoretical model, which determines the capillary characteristics of wood in relation to its structure. The model developed was tested using experimental results, considering the capillary suction height and the water content change after a specific time as boundary values. A comparison between the theoretical model and the experimental results shows that not all the cells in the wood samples take part in the capillary water transport. It also appears that there is a structural resistance to capillary flow.     

Application of a full-scale testing facility for assessing wind-driven-rain intrusion

A new full-scale testing apparatus generically named the Wall of Wind (WoW) has been built by the researchers at the International Hurricane Research Center. The paper discusses the development of a full-scale testing methodology that can be adopted for assessing wind-driven-rain intrusion through the building envelope. The current phase of FIU's WoW is capable of testing full-scale single story building models subjected up to 56 m/s (125 mph) wind speeds and 762 mm/h (30 in./h) of rain. Emphasis has been placed on generating a wind field with a proper boundary-layer profile and turbulence characteristics. Artificial rain has been generated by continuously pumping water through a plumbing system with regularly placed spray nozzles. A large wind and wind-driven-rain field 6.7 m wide by 4.8 m high (22 ft wide by 16 ft high) has been produced, which can engulf the test specimen completely. For example, an assessment of roof secondary water barrier effectiveness in preventing water intrusion is presented. Six different roof secondary water barriers have been investigated. The amount of water intruded through the secondary water barrier and the visual observation of failure have been used as performance indexes. In addition, external and internal pressure measurements, required to explain rain intrusion mechanisms were carried out. Roof slope effects on water intrusion have been investigated by testing three different slopes (2:12, 4:12 and 6:12). Results indicated the following (i) as the slope increases the intrusion decreases, (ii) self-adhered secondary water barrier performed better than nailed secondary water barriers, and (iii) heavy secondary water barriers performed better than light secondary water barriers.     

Models relating traffic safety with road environment and traffic flows on arterial roads in Addis Ababa

This paper presents the study carried out to develop accident predictive models based on the data collected on arterial roads in Addis Ababa. Poisson and negative binomial regression methods were used to relate the discrete accident data with the road and traffic flow explanatory variables. Significant accident predictive models were found with a number of significant explanatory variables. The results show that the existing inadequate road infrastructure and poor road traffic operations are the potential contributors of this ever-growing challenge of the road transport in Addis Ababa. The results also indicate that improvements in roadway width, pedestrian facilities, and access management are effective in reducing road traffic accidents.     

Effect of heat treatment and pH on the thermal,surface, and rheological properties of <Emphasis Type="Italic">Lupinus albus</Emphasis> protein

Endosperm from hand-dissected and- dehulled Lupinus albus seeds was milled into meal, sieved through a 40-mesh screen, and suspended in phosphate buffers (pH 4, 6.8, and 8) at 20% (wt/vol). The suspensions were treated at 75, 90, or 100°C for 1 h. The heat-treated protein was characterized by SDS-PAGE, free zone capillary electrophoresis (FZCE), and DSC; and its surface hydrophobicity, surface tension, and rheological properties were examined. The presence of high M.W. aggregates was apparent from SDS-PAGE and FZCE results. Solubility was lowest at pH 4 and 100°C. DSC analysis was performed on low moisture content samples (3.1%) and 20% (wt/vol) suspensions. DSC analysis at 3.1% moisture content showed a glass transition around 85°C and an exothermic transition at 160°C, whereas the protein suspension showed a more thermally stable protein as indicated by the higher ΔH values. Lupin protein was surface active as demonstrated by its effectiveness in reducing the surface tension of the aqueous phosphate buffer. Surface hydrophobicity of the heat-treated protein decreased as the treatment temperature increased, which supports the SDS-PAGE results. The highest level of aggregation was noted at 90°C and pH 6.8 as indicated by low surface hydrophobicity values. Rheological studies showed direct relationships between the shear storage modulus (G′) of the lupin meal suspension and both pH and temperature treatment, although this effect is minimal at the highest temperature (100°C) and pH 6.8.     

Interfacial adhesion in model bioblends

Model bioblends were investigated for interfacial adhesion using the asymmetric double cantilever beam (ADCB) fracture method. The model bioblends comprised two synthetic polymer components, one of which was the nonbiodegradable polymer polystyrene (PS). The second component was a synthetic biodegradable polyester, which was either polycaprolactone (PCL) or Eastar Bio Copolyester® (EBU). The critical strain energy release rate (G_Ic) data from the ADCB fracture experiments on the model bioblends decreased in the order: PCL/PS > EBU/PS. This was opposite to the reported order in the interfacial tension of these bioblends. It is concluded that the relative interfacial adhesion of the model bioblends was due to better compatibility in PCL/PS blends over that in EBU/PS blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 65–73, 2004