The effect of magnesium hydroxide, hydromagnesite and layered double hydroxide on the heat stability and fire performance of plasticized poly(vinyl chloride)

Emulsion grade PVC was plasticised with 100 phr diisononyl phthalate and filled with 30 phr of different hydrated filler-type flame retardant additives. Static heat stabilities were determined at 200 oC by following the time dependence of hydrogen chloride evolution. Fire retardant performance was studied with a cone calorimeter at a radiant flux of 35 kW m2. The layered double hydroxide outperformed the other fillers with regard to improving static heat stability and also with respect to most fire retardant performance indices.Grants (P2010072800070 and TP13080124921 ‘‘Beneficiation of hydrotalcite’’) from the THRIP programme of the Department of Trade and Industry and the National Research Foundation as well as Greenfield Innovation and Blue Sky Venture Partners.http://jfs.sagepub.comhb201

Piloting a mental health training programme for community health workers in South Africa: an exploration of changes in knowledge, confidence and attitudes

Background There is a shortage of trained mental health workers in spite of the significant contribution of psychiatric disorders to the global disease burden. Task shifting, through the delegation of health care tasks to less specialised health workers such as community health workers (CHWs), is a promising approach to address the human resource shortage. CHWs in the Western Cape province of South Africa provide comprehensive chronic support which includes that for mental illness, but have thus far not received standardized mental health training. It is unknown whether a structured mental health training programme would be acceptable and feasible, and result improved knowledge, confidence and attitudes amongst CHWs. Methods We developed and piloted a mental health training programme for CHWs, in line with the UNESCO guidelines; the WHO Mental Health Gap Action Programme and the South African National framework for CHW training. In our quasi-experimental (before-after) cohort intervention study we measured outcomes at the start and end of training included: 1) Mental health knowledge, measured through the use of case vignettes and the Mental Health Knowledge Schedule; 2) confidence, measured with the Mental Health Nurse Clinical Confidence Scale; and 3) attitudes, measured with the Community Attitudes towards the Mentally Ill Scale. Knowledge measures were repeated 3 months later. Acceptability data were obtained from daily evaluation questionnaires and a training evaluation questionnaire, while feasibility was measured by participant attendance at training sessions. Results Fifty-eight CHWs received the training, with most (n = 56, 97.0%) attending at least 7 of the 8 sessions. Most participants (n = 29, 63.04%) demonstrated significant improvement in knowledge, which was sustained at 3-months. There was significant improvement in confidence, along with changes in attitude, indicating improved benevolence, reduced social restrictiveness, and increased tolerance to rehabilitation of the mentally ill in the community but there was no change in authoritarian attitudes. The training was acceptable and feasible. Conclusions Mental health training was successful in improving knowledge, confidence and attitudes amongst trained CHWs. The training was acceptable and feasible. Further controlled studies are required to evaluate the impact of such training on patient health outcomes. Trial registration PACTR PACTR201610001834198 , Registered 26 October 2016

Heat stabilising flexible PVC with layered double hydroxide derivatives

Please read abstract in the article.The THRIP programme of the Department of Trade and Industry (Grant No. P2010072800070) and the National Research Foundation as well as Greenfield Innovation.http://www.elsevier.com/locate/polydegstabhj201

Magnesium hydroxide derivatives as stabilisers and flame retardants for plasticised poly (vinyl chloride)

The potential of magnesium hydroxide, hydromagnesite and layered double hydroxides (LDHs) as heat stabilisers and flame retardants for plasticised poly (vinylchloride) (PVC) was studied. These inorganic hydrated fillers feature flake-shaped particles with a strong tendency to agglomerate. Filler particles must be homogeneously distributed and individually dispersed in the polymer matrix in order to attain the best performance. For this reason the first step in the investigation was to explore the use of a stearic acid coating in order to improve the dispersability of these fillers in liquids. The platelet morphology-type flame retardants were coated with approximately a monolayer of stearic acid using a solvent technique. Compared to the uncoated powders, the BET surface area was lower, the powder packing density was improved, and the thickening effect on white oil was significantly reduced. The latter two observations were rationalised in terms of a reduction in the attractive interactions between the powder particles. The viscosity of white oil slurries containing 25 wt.% solids showed shear-thinning non-Newtonian behaviour. The coated powders showed significantly lower viscosities at low shear rates although the difference diminished at high shear rates. The lower viscosities shown by the coated powders indicate that the surface modification facilitated the break-up of agglomerates and aided the dispersion of individual particles in the fluid. The thermal decomposition of these hydrated fillers is central to their flame retardant action. At elevated temperatures they endothermically release inert gases. The latter dilute the atmosphere surrounding the burning sample while the endothermic decomposition cools the substrate. These two effects are responsible for the flame retardant action of these fillers. The detailed behaviour of the present samples was studied using thermogravimetric analysis and spectroscopic methods. The decomposition mechanisms, proposed in the literature for these flame retardants, were confirmed. This includes the mass loss, enthalpy of decomposition, and the nature of evolved gases for temperatures up to 1 000 °C. The magnesium hydroxide decomposed endothermically at temperatures well above 250 °C releasing only steam. The LDH decomposed between 225 ºC and 450 ºC and the hydromagnesite between about 220 °C and 500 °C. Both initially released water vapour followed by carbon dioxide. Next the utility of the magnesium hydroxide, hydromagnesite and LDH as combination heat stabilisers and flame retardants for plasticised PVC was studied. Emulsion grade PVC was plasticised with 100 parts per hundred parts of resin (phr) diisononyl phthalate (DINP) and filled with 30 parts per hundred parts of resin (phr) filler additive. Thermomat static heat stabilities were determined at 200 °C by following the time dependence of hydrogen chloride evolution. Fire retardancy was studied using a cone calorimeter at a radiant flux of 35 kW m-2. The layered double hydroxide outperformed the other fillers with regard to improving heat stabilisation and also with respect to most fire retardancy indices. Since the layered double hydroxide performed best it was decided to see whether slight composition variations could improve performance. Derivatives of the standard LDH compound ([Mg0.667Al0.333(OH)2](CO3)0.167·0.44H2O) were synthesised using a hydrothermal method. Again, emulsion grade PVC was plasticised with 100 phr diisononyl phthalate and stabilised with 30 phr of the LDH filler additive derivatives. The heat stability and fire resistance of these compounds were studied. Heat stabilities were determined at 200 °C. The dynamic heat stability tests were performed on the plastisols using the torque rheometer method. Static heat stability was evaluated on the fused compounds. It was evaluated from discoloration profiles of strips exposed for various lengths of time to high heat in a Metrastat oven. The time dependence of hydrogen chloride evolution was followed with a Metrohm Thermomat instrument. The conventional LDH provided the best dynamic heat stability. However, partial replacement of the magnesium with copper significantly delayed the release of volatile HCl. If instead the replacement was done using zinc, better colour retention was achieved. The fire performance was determined at a radiant flux of 35 kWm?2 in a cone calorimeter. The conventional magnesium-aluminium LDH lowered the peak heat release rate of the plasticised PVC from 623 ± 8 kW m?2 to 389 ± 9 kW m?2 and reduced the smoke release by 37 %. Partial replacement of the aluminium with iron resulted in a red pigmented additive that was more effective as a flame retardant reducing the peak heat release rate (pHRR) to as little as 253 ± 5 kW m?2. This additive also showed better smoke suppression (reduction of 44 %) but the best smoke suppression was achieved by replacing part of the magnesium with copper reduction by 49 %).Thesis (PhD)--University of Pretoria, 2015.ChemistryPhDUnrestricte

Layered double hydroxide derivatives as flame retardants for flexible PVC

Please read abstract in the article.The THRIP programme of the Department of Trade and Industry and the National Research Foundation as well as Greenfield Innovation, Engelbrecht & Mentz and Blue Sky Venture Partners.https://onlinelibrary.wiley.com/journal/15213900hj2019Chemical EngineeringChemistr

Layered Double Hydroxide Derivatives as Flame Retardants for Flexible PVC

Please read abstract in the article.The THRIP programme of the Department of Trade and Industry and the National Research Foundation as well as Greenfield Innovation, Engelbrecht & Mentz and Blue Sky Venture Partners.https://onlinelibrary.wiley.com/journal/15213900hj2019Chemical EngineeringChemistr

The influence of stearic acid coating on the properties of magnesium hydroxide, hydromagnesite and hydrotalcite powders

Hydrated filler-type flame retardants were coated with approximately a monolayer of stearic acid using a solvent technique. Compared to the uncoated powders, the BET surface area was lower, the powder packing density was improved, and the thickening effect on white oil was significantly reduced. The latter two observations are rationalized in terms of a reduction in the attractive interactions between the powder particles. The viscosity of white oil slurries containing 25 wt % solids showed shear-thinning non-Newtonian behavior. The coated powders showed significantly lower viscosities at low shear rates although the difference diminished at high shear rates. The lower viscosities shown by the coated powders indicate that the surface modification facilitated the break-up of agglomerates and the dispersion of individual particles in the fluid.Financial support for this research, from the Institutional Research Development Programme (IRDP) of the National Research Foundation of South Africa (NRF) and the THRIP program of the Department of Trade and Industry (administered by the NRF), is gratefully acknowledged