Flame-retarded Polystyrene: Investigating Chemical Interactions between Ammonium Polyphosphate and MgAl Layered Double Hydroxide

Potential flame retardants, MgAl-LDH and ammonium polyphosphate (APP), were added to neat polystyrene (PS) individually or in combinations at weight fractions no greater than 10%. Structural morphologies of MgAl-LDH and the corresponding PS nanocomposites were established via X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) and cone calorimetry were used to study the thermal stability and fire performance of the composites. Time to ignition is greatly reduced for PS composites when compared to the virgin polymer. Synergistic effects were observed in both TGA and cone calorimetry for formulations containing both MgAl-LDH and APP. Physical and chemical interactions between MgAl-LDH and APP are responsible for the observed synergy in thermal stability and fire performance

Nanostructured Layered Copper Hydroxy Dodecyl Sulfate: A Potential Fire Retardant for Poly(vinyl Ester) (PVE)

Composites of poly(vinyl ester) (PVE) with copper hydroxy dodecyl sulfate (CHDS) were prepared by thermal curing. The efficiency of the additive, CHDS, in reducing flammability is demonstrated via cone calorimetry and thermogravimetric analysis (TGA). The addition of 1-10% by mass of the CHDS additive resulted in significant increments in char formation (~4-11%) from thermogravimetric analysis (TGA). Incorporation of the CHDS into the polymer matrix at these low concentrations leads to substantial reductions in the total heat release (~20-30%) but no significant change in the peak heat release rate. The composite materials generally ignite more quickly, however, the flame extinguishes faster for the composites relative to the virgin polymer. X-ray diffraction (XRD) and infrared spectroscopic analyses of the residues collected at various stages during thermal decomposition of the composities, suggest the participation of copper-containing species in promoting enhanced thermal stability of PVE

Delineation of individual tree crowns from ALS and hyperspectral data: A comparison among four methods

In this paper four different delineation methods based on airborne laser scanning (ALS) and hyperspectral data are compared over a forest area in the Italian Alps. The comparison was carried out in terms of detected trees, while the ALS based methods are compared also in terms of attributes estimated (e.g. height). From the experimental results emerged that ALS methods outperformed hyperspectral one in terms of tree detection rate in two of three cases. The best results were achieved with a method based on region growing on an ALS image, and by one based on clustering of raw ALS point cloud. Regarding the estimates of the tree attributes all the ALS methods provided good results with very high accuracies when considering only big trees

Extraction of tree trunk shape from a terrestrial laser scanning point cloud using the ransac algorithm

This BA thesis deals with a procedure for the extraction of a trunk shape and the calculation of the trunk parameters from a terrestrial laser point cloud of a tree. The tree trunk geometry has been simplified, so that it was modelled with a single and multiple cylinders. Two algorithms were employed for solving the problem: we used the RANSAC algorithm for the determination of the approximate values of the parameters and the extraction of the trunk shape, and the least squares method for the estimation of the parameters of the cylinder/cylinders with associated accuracies and for the calculation of the deviation between the model and the extracted point cloud. The process was carried out in different situations. The trunk was cut into partitions of different lengths, and for each partition, the parameters of the cylinder were calculated and the points which best fit the cylinder were extracted. Experimentally, we analysed one, seven, and fourteen slices. The results were different 3D models of the trunk, composed of a different number of smaller cylinders. The resulting 3D models of the trunk were visually and graphically compared with the corresponding extracted point cloud. We have proved that by increasing the number of slices, we improve the description of the trunk shape and determine the parameters of the trunk more accurately. \ud \ud \ud \u

Psihološki odgovor sportaša na ozljedu

The aim of this research was to investigate the causes of the emergence of sports injuries and to explain the differences in psychological response with regard to the severity of the injury. We examined 68 competing Slovene athletes with surgically treated knee injury. The estimated time of rehabilitation of the more severely injured athletes was six months, while those who sustained less severe injuries faced a monthlong rehabilitation. We measured the athletes’ personality traits, their athletic identity, coping with pain, rehabilitation beliefs, motivation and social support provided by their family and their coach as well as their colleagues. The results showed that the group of more severely injured athletes demonstrated behaviour that is less inhibited in response than the group of athletes with less severe injuries. The psychological response proved to be almost the same in both groups, except for the higher levels of catastrophizing, and a higher individual coping response found in the group of more severely injured athletes. Furthermore, masculinity was found to predict self-efficacy and the individual coping response, the strength of athletic identity predicted motivation and rehabilitation value, while emotional lability predicted catastrophizing and self-efficacy. Athletes with lower athletic identity, lower masculinity and higher emotional lability are more exposed to adjustment difficulties after sustaining an athletic injury. In our opinion, the strategies for successful rehabilitation after a sports injury should be aimed at the identification of athletes with personality traits that pose a higher risk of experiencing adjustment difficulties, at promoting adequate motivation, increasing coach support and at the application of cognitive-behavioural strategies.Cilj je ovog istraživanja bio utvrditi uzroke nastajanja sportskih ozljeda te objasniti razlike u psihološkom odgovoru na ozljede različite težine. Istražili smo 68 slovenskih natjecatelja koji su bili podvrgnuti kirurškoj operaciji koljena. Procijenjeno vrijeme rehabilitacije za teže ozlijeđene sportaše iznosilo je šest mjeseci, dok je za one ispitanike s manje teškim ozljedama ono iznosilo jedan mjesec. Mjerili smo sportaševe osobine ličnosti, njihov sportski identitet, sposobnost suočavanja s boli, povjerenje u rehabilitacijski proces te motivacijsku i sociološku potporu koju su sportaši dobivali od svoje obitelji, trenera i kolega. Rezultati su pokazali da je grupa ispitanika koja je bila teže ozlijeđena pokazala oblik ponašanja koji je manje inhibirao reakciju na ozljedu no što je to slučaj s grupom ispitanika koji su bili lakše ozlijeđeni. Psihološki odgovor bio je gotovo isti u obje grupe, s iznimkom veće razine katastrofiziranja i individualnog suočavanja u grupi ispitanika koji su bili teže ozlijeđeni. Nadalje, pokazalo se da razina muškosti objašnjava samoučinkovitost i razinu individualnog suočavanja, snaga sportskog identiteta predviđa motivaciju i rehabilitacijsku vrijednost, dok je emocionalna nestabilnost predviđala razinu katastrofiziranja i samoučinkovitosti. Sportaši s nižom razinom sportskog identiteta, muškosti i većom razinom emotivne nestabilnosti bili su više izloženi poteškoćama u prilagodbi nakon ozljeđivanja. Prema našem mišljenju, strategije za uspješnu rehabilitaciju nakon sportske ozljede trebale bi biti usmjerene na identifikaciju sportaša s osobinama ličnosti koje predstavljaju veći rizik za doživljavanje poteškoća u prilagodbi na trenutačno stanje, zatim na poticanje odgovarajuće motivacije, povećavanje potpore trenera te primjenu kognitivno-bihevioralnih strategija

Compression load failure of aluminum plates due to fire

An experimental study was performed to quantify the response and failure of 5083-H116 and 6082-T6 aluminum plates under compression load while being subjected to a constant heat flux representing a fire exposure. Using an intermediate scale loading frame with integrated heating, the study evaluated the effects of geometry, aluminum type, fire exposure, load, and fire protection. Intermediate scale aluminum panels which were more than 0.7 m high and 0.2 m wide were used to gain insights into the structural behavior of large structural sections exposed to fire. Failure temperatures were measured to range from 100 to 480 C and were dependent on applied stress and aluminum type. This indicates that the use of a single temperature criterion in fire resistance without load as typically done is not sufficient for evaluating structural response during fire. An empirical failure model was developed to account for fire exposure conditions, aluminum type, and geometr

One step synthesis of Cu2ZnSnS4 nanoflakes by microwave irradiation technique and effect of Cu concentration

The influence of cyclic microwave irradiation and effect of Cu concentration has been investigated for synthesis of pure phase Cu2ZnSnS4 powder. It has been observed that Cu concentration plays a vital role to get pure phase Cu2ZnSnS4. The optical properties, phase purity, crystallographic structure and morphology have been investigated by spectroscopic and microscopic techniques. The results reveal that single phase kesterite Cu2ZnSnS4 with no other secondary phase can be obtained by precisely controlling the cyclic microwave irradiation time and the precursor concentrations. The optical band gap of prepared Cu2ZnSnS4 powder, estimated from UV-Visible spectroscopy has been found to be ~ 1.45 eV which is superlative for photovoltaic application. Systematic Raman study confirms the formation of Cu2ZnSnS4 phase and suppression of CuS peak with proper control in copper concentration. TEM image shows nanoflakes kind of morphology having thickness of flakes between 25 nm to 45 nm. Further the crystal inter-planer spacing is found to be 0.32 nm, which is consistent with the XRD data and ascribed to (112) plane

Micromechanical finite element analyses of fire retardant woven fabric composites at elevated temperatures using unit cells at multiple length scales

This paper presents a micromechanical Finite Element (FE) model developed to predict the effective mechanical properties of glass fibre-reinforced (woven fabric) polymer composites with/without fire retardant particulate additives at elevated temperatures. The elevated mechanical properties of glass fibre-reinforced epoxy composites with/without fire retardants were predicted using three unit cells of varying length scales in micromechanical FE analysis. Theoretically predictions of flexural behaviour of these fibre-reinforced polymer composites at elevated temperatures were satisfactorily validated against experimentally measured data. The numerical model developed herein was then used for the prediction of other mechanical properties of fibre-reinforced polymer composites that would have been difficult to collect at elevated temperatures. Micromechanical FE models such as the one contained in this paper are useful to architectural engineers as they can be used to guide the design and qualification of new engineering composites that satisfy stringent Building codes in fire prone engineering applications

Preparation and characterization of core/shell-like intumescent flame retardant and its application in Polypropylene

With a shell of starch-melamine-formaldehyde (SMF) resin, core/shell-like ammonium polyphosphate (SMFAPP) is prepared by in situ polymerization, and is characterized by SEM, FTIR and XPS. The shell leads SMFAPP a high water resistance and flame retardance compared with APP in polypropylene (PP). The flame retardant action of SMFAPP and APP in PP are studied using LOI, UL 94 test and cone calorimeter, and their thermal stability is evaluated by TG. The flame retardancy and water resistance of the PP/SMFAPP composite at the same loading is better than that of the PP/APP composite. UL 94 ratings of PP/SMFAPP can reach V-0 at 30 wt% loading. The flame retardant mechanism of SMFAPP was studied by dynamic FTIR, TG and cone calorimeter, etc