Analysis of rubber vulcanisates

A study has been made, using High Pressure Liquid Chromatography, of the migration of TMQ (a quinoline type) and 6PPD (a paraphenylenediamine type) antidegradants from a tyre sidewall compound into adjacent casing and liner compounds containing no antidegradant. Migration takes place at a rapid rate, even during the vulcanisation of the composite. After 4000 hours ageing in nitrogen at 100oC, there is a higher level of antidegradants in the casing than in the sidewall. An equilibrium distribution is not obtained. After 114 days at 50oC in 95% relative humidity, the level of solvent extractable 6PPD fell to zero, but subsequent ageing for 2 years in 50 pphm ozone showed no evidence of sidewall cracking. It is suggested that the antidegradant is still active but linked to the polymer chain. An analytical method, for the type and amount of sulphenamide accelerators in vulcanised rubber compounds, has been developed. During the vulcanisation process, the accelerators decay, liberating specific amines which have been solvent extracted, derivatised with 1-chloro-2,4-dinitrobenzene and the yellow coloured zwitter ion analysed using High Pressure Liquid Chromatography. The decay of the accelerator and sulphur during the vulcanisation process, has been studied. It has been demonstrated that the sulphur crosslinking with a styrenebutadiene polymer is a first order reaction, after an initial period during which the accelerator content falls to zero. Variations in sulphur to accelerator ratios gave consistent rate constants for the crosslinking, except for a sulphur level of less than 1% by weight and a ratiio of accelerator to sulphur of 1:1.3. The retention time of the reaction product between sulphur and accelerator from an HPLC column changes with cure time, showing that the precurser to crosslinking is an ever changing material. One of these reaction products has been analysed.

Individual differences in work behaviour of blue-collar workers : a study of rubber tappers in Malaysia

This thesis examines individual differences in work behaviour of rubber tappers. The study examined sex, age, experience and race differences and their interactions with terrain on job performance, absenteeism, and job satisfaction of 1053 rubber tappers. Rubber tappers are unskilled blue-collar workers who essentially do the same type of work and are paid the same rates of pay. There are very few studies that have compared male and female blue-collar workers doing similar jobs in organisational settings. This study is one of the few investigations that examine sex differences in job performance of blue-collar workers doing same job using production data. Studies on age differences in work behaviour encounter numerous methodological difficulties such as high turnover, internal transfers and problems associated with age differences in educational levels. The participation of rubber tappers in this study is envisaged to overcome these difficulties because attrition rates of rubber tappers are low, and internal transfers are non existent. Further, the educational levels of rubber tappers are relatively similar across different age cohorts, as most rubber tappers have little or no education. Two measures of both job performance and absenteeism were derived from payroll records. The two job performance measures were total crop production and attendance. The two absenteeism measures were avoidable and unavoidable absence rates. Overall job satisfaction was determined using a 4-item scale. Significant sex, age, experience and race differences were obtained for job performance, absenteeism and job satisfaction. Significant interactive effects were also obtained for sex, age , experience, race and terrain for job performance and absenteeism. The results are discussed in relation to the abilities and motivation of rubber tappers. The implication of these findings for employee selection and human resource management in rubber estates is discussed.

Branded lives:the production and consumption of meaning at work

'Branded Lives explodes the myth that a brand must, or even can stand for one unified, easily communicated message. While warning of the dangers of managing to preserve this myth, the book also celebrates the plurality of brand meanings generated by those employed to serve both the brand and the customer. I recommend reading this book in its entirety. If you are like me, your reading will bring a refreshing fullness to the experience of brands and branding and many new insights.' - Mary Jo Hatch, University of Virginia, US. © Matthew J. Brannan, Elizabeth Parsons and Vincenza Priola 2011. All rights reserved.

The synthesis and mechanism of action of organic accelerators of the sulphur vilcanisation of rubber

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An analysis of factors influencing the consumption of aluminum in the UK

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'Why don't you try it again?' A comparison of parent led, home based interventions aimed at increasing children's consumption of a disliked vegetable

Previous research suggests that the use of modelling and non-food rewards may be effective at increasing tasting, and consequential liking and acceptance, of a previously disliked food. Although successful school-based interventions have been developed, there is a lack of research into home-based interventions using these methods. This study aimed to develop and investigate the efficacy of a parent led home-based intervention for increasing children's acceptance of a disliked vegetable. A total of 115 children aged 2-4 years were allocated to one of four intervention groups or to a no-treatment control. The four intervention conditions were: repeated exposure; modelling and repeated exposure; rewards and repeated exposure; or modelling, rewards and repeated exposure. Children in all of the intervention conditions were exposed by a parent to daily offerings of a disliked vegetable for 14 days. Liking and consumption of the vegetable were measured pre and post-intervention. Significant increases in post-intervention consumption were seen in the modelling, rewards and repeated exposure condition and the rewards and repeated exposure condition, compared to the control group. Significant post-intervention differences in liking were also found between the experimental groups. Liking was highest (>60%) in the modelling, rewards and repeated exposure group and the rewards and repeated exposure group, intermediate (>26%) in the modelling and repeated exposure and repeated exposure groups, and lowest in the control group (10%). Parent led interventions based around modelling and offering incentives may present cost efficient ways to increase children's vegetable consumption.

Consumption of bilberries controls gingival inflammation

Bioactive molecules in berries may be helpful in reducing the risk of oral diseases. The aim of this study was to determine the effect of bilberry consumption on the outcome of a routine dental clinical parameter of inflammation, bleeding on probing (BOP), as well as the impact on selected biomarkers of inflammation, such as cytokines, in gingival crevicular fluid (GCF) in individuals with gingivitis. Study individuals who did not receive standard of care treatment were allocated to either a placebo group or to groups that consumed either 250 or 500 g bilberries daily over seven days. The placebo group consumed an inactive product (starch). A study group, receiving standard of care (debridement only) was also included to provide a reference to standard of care treatment outcome. Cytokine levels were assayed using the Luminex MagPix system. The mean reduction in BOP before and after consumption of test product over 1 week was 41% and 59% in the groups that consumed either 250 or 500 g of bilberries/day respectively, and was 31% in the placebo group, and 58% in the standard of care reference group. The analysis only showed a significantreduction in cytokine levels in the group that consumed 500 g of bilberries/day. A statistically significant reduction was observed for IL-1β (p = 0.025), IL-6 (p = 0.012) and VEGF (p = 0.017) in GCF samples in the group that consumed 500 g of bilberries daily. It appears that berry intake has an ameliorating effect on some markers of gingival inflammation reducing gingivitis to a similar extent compared to standard of care.

Influencing water consumption at South Staffordshire Water PLC : a disaggregated behavioural analysis of contributory factors

This research identifies factors which influence the consumption of potable water supplied to customers' property. A complete spectrum of the customer base is examined including household, commercial and industrial properties. The research considers information from around the world, particularly demand management and tariff related projects from North America. A device termed the Flow Moderator was developed and proven, with extensive trials, to conserve water at a rate equivalent to 40 litres/property/day whilst maintaining standards-of-service considerably in excess of Regulatory requirements. A detailed appraisal of the Moderator underlines the costs and benefits available to the industry through deliberate application of even mild demand management. More radically the concept of a charging policy utilising the Moderator is developed and appraised. Advantages include the lower costs of conventional fixed-price charging systems coupled with the conservation and equitability aspects associated with metering. Explanatory models were developed linking consumption to a range of variables demonstrated that households served by a communal water service-pipe (known in the UK as a shared supply) are subject to associated restrictions equivalent to -180 litres/property/day. The research confirmed that occupancy levels were a significant predictive element for household, commercial and industrial customers. The occurrence of on-property leakage was also demonstrated to be a significant factor recorded as an event which offers considerable scope for demand management in its own right.

Effect of the base station antenna beam tilting on energy consumption in cellular networks

The objective of this paper is to combine the antenna downtilt selection with the cell size selection in order to reduce the overall radio frequency (RF) transmission power in the homogeneous High-Speed Packet Downlink (HSDPA) cellular radio access network (RAN). The analysis is based on the concept of small cells deployment. The energy consumption ratio (ECR) and the energy reduction gain (ERG) of the cellular RAN are calculated for different antenna tilts when the cell size is being reduced for a given user density and service area. The results have shown that a suitable antenna tilt and the RF power setting can achieve an overall energy reduction of up to 82.56%. Equally, our results demonstrate that a small cell deployment can considerably reduce the overall energy consumption of a cellular network.

Efficient functionalisation of ethylene-propylene rubber in the presence of comonomer

The main aim of this work was to investigate the effect of a highly reactive comonomer, divinylbenzene (DVB), on the extent of melt grafting of glycidyl methacrylate (GMA) on ethylene-propylene rubber (EPR) using 2,5-dimethyl-2,5-bis-(tert-butyl peroxy) hexane (Trigonox 101, T101) as a free radical initiator, and to compare the results with a conventional grafting of the same monomer on EPR. To achieve this, the effect of processing conditions and chemical composition including the concentration of peroxide, GMA and DVB on the extent of grafting was investigated. The presence of the comonomer (DVB) in the grafting process resulted in a significant increase in the extent of the grafting using only a small concentration of peroxide. It was also found that the extent of grafting increased drastically with the increasing DVB concentration. Interestingly, in the comonomer system, the extent of the undesired side reaction, normally the homopolymerisation of GMA (polyGMA) was shown to have reduced tremendously and in most cases the level of polyGMA was immeasurable in the samples. In contrast, the extent of grafting in conventional system increased with increasing the peroxide concentration but the level of grafting was much lower than in the case of DVB. Homopolymerisation of GMA and excessive crosslinking of EPR became dominant at high peroxide concentration and this reflects that the side reactions were favourable in the conventional grafting system.