Flame retardant properties of polymer composites of urea complex of magnesium and vermiculite

Polymeric materials are increasingly used in several applications. However, their relatively high flammability presents a danger to people and property. Their use therefore requires that they are made more resistant to both the initiation and propagation of fires. In the present work we evaluate, by cone calorimeter tests, the efficiency of urea complex of magnesium and vermiculite (urea- vermiculite) as a stand-alone flame retardant in polyurethane (PU) resin and flexible polyvinyl chloride (PVC). Flexible PVC cone calorimeter tests proceeded without a visible flame following an initial short-lived ignition which degenerated into a bulk pyrolysis, in combination with a surface glowing-combustion event. Urea-vermiculite formed an exfoliated protective barrier layer which allowed thermal stabilisation of the condensed phase. The simultaneous release of halogen species by the PVC and the action of the exfoliated barrier layer prevented the formation of a flammable air–fuel mixture. The addition of urea-vermiculite lowered the peak heat release rate (pHRR) and the total heat released (tHR) significantly. In PU composites the urea-vermiculite was unable to form a cohesive protective barrier layer. The poor compatibility between the molten PU and the exfoliated flakes also led to the consumption of the underlying PU. Nevertheless, the addition of urea-vermiculite lowered significantly the pHRR of PU composites. In general, cone calorimetry results revealed that urea-vermiculite allowed thermal stabilization of the condensed phase at high temperatures but had little influence in the vapour phase behaviour. The amount of released urea’s degradation products (non-flammable vapours) was not enough to dilute the flammable vapours’ mixture. Thereby when used with PVC, which releases halogen flame poison, it showed great fire performance.http://scitation.aip.org/content/aip/proceeding/aipcp2020-01-22am2019Chemical Engineerin

Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017

A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4 (62.3 (55.1�70.8) million) to 6.4 (58.3 (47.6�70.7) million), but is predicted to remain above the World Health Organization�s Global Nutrition Target of <5 in over half of LMICs by 2025. Prevalence of overweight increased from 5.2 (30 (22.8�38.5) million) in 2000 to 6.0 (55.5 (44.8�67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic. © 2020, The Author(s)

Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017 (Nature Medicine, (2020), 26, 5, (750-759), 10.1038/s41591-020-0807-6)

An amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2020, The Author(s)

Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017 (Nature Medicine, (2020), 26, 5, (750-759), 10.1038/s41591-020-0807-6)

An amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2020, The Author(s)

Rotomolded antistatic and flame-retarded graphite nanocomposites

Graphite nanoplatelets with an average particle size of 13 μm and an estimated flake thickness of about 76 nm were prepared by microwave exfoliation, followed by ultrasonication-assisted liquid-phase delamination, of an expandable graphite. This nanoadditive was used to fabricate linear low-density polyethylene (LLDPE) and poly(ethylene-co-vinyl acetate) (EVA)-based nanocomposite sheets using rotational molding. The dry blending approach yielded surface resistivities within the static dissipation range at filler loadings as low as 0.25 wt.% (0.1 vol.%). However, even at this low graphite content, impact properties were significantly reduced compared to the neat polymers. Bilayer moldings via the double dumping method proved to be a feasible approach to achieve both acceptable mechanical properties and antistatic properties. This was achieved by rotomolding nanocomposite sheets with a 1-mm outer layer containing the filler and a 2-mm inner layer of neat LLDPE. Excellent fire resistance, in terms of cone calorimeter testing, was achieved when the outer layer also contained 10 wt.% expandable graphite.http://journals.sagepub.com/home/jtchj2018Chemical Engineerin

Flame retardant properties of polymer composites of urea complex of magnesium and vermiculite

Polymeric materials are increasingly used in several applications. However, their relatively high flammability presents a danger to people and property. Their use therefore requires that they are made more resistant to both the initiation and propagation of fires. In the present work we evaluate, by cone calorimeter tests, the efficiency of urea complex of magnesium and vermiculite (urea- vermiculite) as a stand-alone flame retardant in polyurethane (PU) resin and flexible polyvinyl chloride (PVC). Flexible PVC cone calorimeter tests proceeded without a visible flame following an initial short-lived ignition which degenerated into a bulk pyrolysis, in combination with a surface glowing-combustion event. Urea-vermiculite formed an exfoliated protective barrier layer which allowed thermal stabilisation of the condensed phase. The simultaneous release of halogen species by the PVC and the action of the exfoliated barrier layer prevented the formation of a flammable air–fuel mixture. The addition of urea-vermiculite lowered the peak heat release rate (pHRR) and the total heat released (tHR) significantly. In PU composites the urea-vermiculite was unable to form a cohesive protective barrier layer. The poor compatibility between the molten PU and the exfoliated flakes also led to the consumption of the underlying PU. Nevertheless, the addition of urea-vermiculite lowered significantly the pHRR of PU composites. In general, cone calorimetry results revealed that urea-vermiculite allowed thermal stabilization of the condensed phase at high temperatures but had little influence in the vapour phase behaviour. The amount of released urea’s degradation products (non-flammable vapours) was not enough to dilute the flammable vapours’ mixture. Thereby when used with PVC, which releases halogen flame poison, it showed great fire performance.http://scitation.aip.org/content/aip/proceeding/aipcp2020-01-22am2019Chemical Engineerin

Global injury morbidity and mortality from 1990 to 2017: Results from the global burden of disease study 2017

Background Past research in population health trends has shown that injuries form a substantial burden of population health loss. Regular updates to injury burden assessments are critical. We report Global Burden of Disease (GBD) 2017 Study estimates on morbidity and mortality for all injuries. methods We reviewed results for injuries from the GBD 2017 study. GBD 2017 measured injury-specific mortality and years of life lost (YLLs) using the Cause of Death Ensemble model. To measure non-fatal injuries, GBD 2017 modelled injury-specific incidence and converted this to prevalence and years lived with disability (YLDs). YLLs and YLDs were summed to calculate disability-adjusted life years (DALYs). Findings In 1990, there were 4 260 493 (4 085 700 to 4 396 138) injury deaths, which increased to 4 484 722 (4 332 010 to 4 585 554) deaths in 2017, while age-standardised mortality decreased from 1079 (1073 to 1086) to 738 (730 to 745) per 100 000. In 1990, there were 354 064 302 (95% uncertainty interval: 338 174 876 to 371 610 802) new cases of injury globally, which increased to 520 710 288 (493 430 247 to 547 988 635) new cases in 2017. During this time, age-standardised incidence decreased non-significantly from 6824 (6534 to 7147) to 6763 (6412 to 7118) per 100 000. Between 1990 and 2017, age-standardised DALYs decreased from 4947 (4655 to 5233) per 100 000 to 3267 (3058 to 3505). Interpretation Injuries are an important cause of health loss globally, though mortality has declined between 1990 and 2017. Future research in injury burden should focus on prevention in high-burden populations, improving data collection and ensuring access to medical care. © Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ

Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017 (Nature Medicine, (2020), 26, 5, (750-759), 10.1038/s41591-020-0807-6)

An amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2020, The Author(s)