Tuning High and Low Temperature Foaming Behavior of Linear and Long-Chain Branched Polypropylene via Partial and Complete Melting

While existing foam studies have identified processing parameters, such as high-pressure drop rate, and engineering measures, such as high melt strength, as key factors for improving foamability, there is a conspicuous absence of studies that directly relate foamability to material properties obtained from fundamental characterization. To bridge this gap, this work presents batch foaming studies on one linear and two long-chain branched polypropylene (PP) resins to investigate how foamability is affected by partial melting (Method 1) and complete melting followed by undercooling (Method 2). At temperatures above the melting point, similar expansion was obtained using both foaming procedures within each resin, while the PP with the highest strain hardening ratio (13) exhibited the highest expansion ratio (45 ± 3). At low temperatures, the foamability of all resins was dramatically improved using Method 2 compared to Method 1, due to access to lower foaming temperatures (<150 °C) near the crystallization onset. Furthermore, Method 2 resulted in a more uniform cellular structure over a wider temperature range (120–170 °C compared to 155–175 °C). Overall, strong extensional hardening and low onset of crystallization were shown to give rise to foamability at high and low temperatures, respectively, suggesting that both characteristics can be appropriately used to tune the foamability of PP in industrial foaming applications.

Experimental Study on Solar Heat Battery using Phase Change Materials for Parabolic Dish Collectors

Energy consumption has increased withthe population increase, and fossil fuel dependency has risen and causing pollutions. Solar energy is suitableto provide society's thermo-electric needs. Thermal energy storage-based concentrated solar receivers are aimed at store heat energy and transportable to the applications. Acavity receiver with two-phase change materials (PCM) is experimentally investigated using a parabolic dish collector to act as the solar heat battery. The selected PCMs are MgCl2.6H2O and KNO3-NaNO3. PCMs are chosen and placed as perthe temperature zones of the receiver. The outdoor test wasconductedto determine the conical receiver's storage performance using cascaded PCMs. The complete melting of PCM attainsat an average receiver surface temperature of 230°C. The complete melting of the PCM in the receiver took around 30 minutes at average radiation around 700 W/m2, and heat stored is approximately 5000 kJ. The estimated number of cavity receivers to be charged on a sunny day is about 10-15 according to the present design and selected PCMs, for later use

Degradation kinetics of oligo(ε-caprolactone) ultrathin films: Influence of crystallinity

The potential of using crystallinity as morphological parameter to control polyester degradation in acidic environments is explored in ultrathin films by Langmuir technique. Films of hydroxy or methacrylate end-capped oligo(ε-caprolactone) (OCL) are prepared at the air–water interface as a function of mean molecular area (MMA). The obtained amorphous, partially crystalline or highly crystalline ultrathin films of OCL are hydrolytically degraded at pH ~ 1.2 on water surface or on silicon surface as-transferred films. A high crystallinity reduces the hydrolytic degradation rate of the films on both water and solid surfaces. Different acceleration rates of hydrolytic degradation of semi-crystalline films are achieved either by crystals complete melting, partially melting, or by heating them below their melting temperatures. Semi-crystalline OCL films transferred via water onto a solid surface retain their crystalline morphology, degrade in a controlled manner, and are of interest as thermoswitchable coatings for cell substrates and medical devices. Graphic abstract

Structural transformations of a gas-atomized Al62.5Cu25Fe12.5 alloy during detonation spraying, spark plasma sintering and hot pressing

In this work, we traced structural transformations of an Al62.5Cu25Fe12.5 alloy, in which a quasicrystalline icosahedral phase (i-phase) can be formed, upon spraying onto a substrate and consolidation from the powder into the bulk state. The Al62.5Cu25Fe12.5 powder was obtained by gas atomization and consisted of i-phase and ?-phase AlCu(Fe). The powder was detonation sprayed (DS) and consolidated by spark plasma sintering (SPS)/hot pressing (HP). During DS, the particles experienced partial or complete melting and rapid solidification, which resulted in the formation of coatings of a complex structure. The composite regions containing i-phase were inherited from the powder alloy. The fraction of the material that experienced melting solidified as ?-phase AlFe(Cu) in the coating. It was suggested that the difficulty of obtaining i-phase upon post-spray annealing is related to aluminum depletion of the alloy during DS. During SPS and HP, the elemental composition of the alloy was preserved, while the exposure to an elevated temperature led to phase homogenization. SPS and HP conducted at 700?C resulted in full densification and the formation of a single-phase quasicrystalline alloy. The sintered single-phase alloy showed a higher microhardness in comparison with the DS coatings.

A mushy Earth's mantle for more than 500 Myr after the magma ocean solidification

SUMMARY In its early evolution, the Earth mantle likely experienced several episodes of complete melting enhanced by giant impact heating, short-lived radionuclides heating and viscous dissipation during the metal/silicate separation. After a first stage of rapid and significant crystallization (Magma Ocean stage), the mantle cooling is slowed down due to the rheological transition, which occurs at a critical melt fraction of 40–50%. This transition first occurs in the lowermost mantle, before the mushy zone migrates toward the Earth's surface with further mantle cooling. Thick thermal boundary layers form above and below this reservoir. We have developed numerical models to monitor the thermal evolution of a cooling and crystallizing deep mushy mantle. For this purpose, we use a 1-D approach in spherical geometry accounting for turbulent convective heat transfer and integrating recent and solid experimental constraints from mineral physics. Our results show that the last stages of the mushy mantle solidification occur in two separate mantle layers. The lifetime and depth of each layer are strongly dependent on the considered viscosity model and in particular on the viscosity contrast between the solid upper and lower mantle. In any case, the full solidification should occur at the Hadean–Eoarchean boundary 500–800 Myr after Earth's formation. The persistence of molten reservoirs during the Hadean may favor the absence of early reliefs at that time and maintain isolation of the early crust from the underlying mantle dynamics.

Melting ranges of heterophase systems Zr – Si – ZrB2 – ZrSi2-MoSi2 and Zr – Si – HfB2 – HfSi2 – MoSi2

The work is devoted to studying the melting ranges of the base Zr – Si eutectic composition depending on the content of the heterophasic powder component in the ZrB2 – ZrSi2 – MoSi2 and HfB2 – HfSi2 – MoSi2 systems in an amount of 30 – 90 % obtained by the method of self-propagating high-temperature synthesis (SHS). The melting range of the mixture Zr – Si was 1420 – 1440 °C, while the addition of SHS-powders ZrB2 – ZrSi2 – MoSi2 led to an increase in the melting onset temperature Тmelt.onset to 1460 – 1560 °С and the complete melting temperature Tmelt.complete to 1480 – 1670 °C. The addition of HfB2 – HfSi2 – MoSi2 powders had a weak effect on the values of Тmelt.onset (1390 – 1430 °С), but led to an increase in the values of Tmelt.complete to 1510 – 1550 °С. X-ray phase analysis showed that the remelted samples contained ZrB2/HfB2, ZrSi2/HfSi2, MoSi2 phases and Si, with the number of phases being directly proportional to the content of SHS powders in the composition of the Zr – Si mixture. The ingots were characterized by a homogeneous structure consisting of a silicon matrix, ZrSi2/HfSi2, MoSi2 disilicide grains, with ZrB2/HfB2 diboride inclusions.

Antioxidant Activity, Physiochemical and Sensory Characteristics of Ice Cream Incorporated with Sloe Berry (Prunus spinosa L.)

The aim of this study was to determine the influence of sloe berry (SB) addition at different ratios on the physical, chemical, antioxidant, colour and sensory properties and mineral contents of ice creams. The increment of SB led to the an increase of titratable acidity, overrun, viscosity and ash values, first dripping and complete melting times; in contrast, it decreased the total solid, pH and fat values. Mn and Zn values were affected significantly (P < 0.05) by the addition of SB but other element levels were not affected. L* and b* values decreased significantly in all samples as compared with control sample, while a*, H°, C* and ∆E* increased significantly with addition of SB. Antioxidant activity was the highest in the sample containing 15 % SB (w/w) among ice cream samples. The ice cream samples containing 15 % SB had higher score than the control sample in terms of colour and appearance, gumming structure and general acceptability.

A Preliminary Study of the Effects of Micro-Encapsulated Phase Change Materials Intermixed With Grout in Vertical Borehole Heat Exchangers

A thermal analysis of a GCHP system is performed to investigate the effect of adding micro-encapsulated PCM into the borehole grout to improve the thermal performance of GCHP systems. The apparent heat capacity method is used in the numerical model, simulated in COMSOL. The PCM’s thermal properties were varied to study the effect of each property, such as PCM melting temperature, transition temperature range, PCM thermal conductivity, and the amount of PCM within the grout. Even though the low thermal conductivity of PCM compared to ordinary grout adversely affects the GCHP system performance, a potential reduction (∼2%) in borehole length is achieved. The best melting temperature is that which results in a complete melting of PCM around the peak load, instead of around the average load. The melting temperature must be chosen properly for each GCHP scenario, otherwise the benefit from using PCM may not be achieved. There is an insignificant change in the heat pump consumption because EFT is more favorable in PCM cases around the melting temperature, but less favorable after melting completely.

Hydrate Remediation Philosophy for a New Flowline Intervention System Based on Active Heating

The Electrically Trace Heated Blanket (ETH-Blanket) is a new offshore intervention system currently in development by TechnipFMC for the efficient remediation of plugs due to hydrates or wax deposit in subsea production and injection flowlines. The ETH-Blanket consists of a network of heating cables placed underneath an insulation layer which is laid onto the seabed above the plugged flowline. By applying electrical power to the cables, heat is generated by Joule effect which warms up the flowline content until hydrate dissociation or wax plug remediation through softening or complete melting. The ETH-Blanket is currently developed within a Joint Industry project (JIP) between TechnipFMC and Total. The dissociation of hydrate plugs using active heating incurs a number of risks for the integrity of the flowline and for the restoration of production to nominal conditions. As the flowline content is warmed up from ambient to hydrate dissociation temperature and during the dissociation of the hydrate plug, the pressure inside the flowline may potentially increase above design limits due to hydrate degassing and fluid volume expansion. Also, plug run-away scenarios may occur if a large pressure difference exists between both sides of the plug. The remediation operation may fail because of insufficient power or misplacement of the ETH-Blanket. Lastly, even following successful operation of the ETH Blanket, new flowline blockage may occur during subsequent operations such as cold re-start. To mitigate those risks, a hydrate remediation philosophy has been developed specifically for the ETH-Blanket Service. It is based on the development of in-house tools and procedures and builds upon experimental and modelling work performed as part of a previous JIP focusing on the dissociation of hydrate plugs using an ETH-Pipe-in-Pipe [1]. This paper introduces the different elements of the hydrate remediation philosophy, including the development and experimental validation of the dedicated tools used to define the appropriate heating sequence for the safe and efficient dissociation of hydrate plugs.