scholarly journals High-Pressure Crystallization of iPP Nucleated with 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol

Polymers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 145
Author(s):  
Przemyslaw Sowinski ◽  
Ewa Piorkowska ◽  
Severine A. E. Boyer ◽  
Jean-Marc Haudin
Keyword(s):  
Grain Size ◽  
High Pressure ◽  
Isotactic Polypropylene ◽  
Thermal Conditions ◽  
Elevated Pressure ◽  
Lower Pressure ◽  
Effect Of Pressure ◽  
Cooling Crystallization ◽  
Polycrystalline Aggregates ◽  
Pressure Crystallization

1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol (DMDBS) is highly effective in nucleation of the α- form of isotactic polypropylene (iPP). However, its role in high-pressure crystallization of iPP, facilitating the formation of the γ- polymorph, has not been explored. The present paper focuses on the influence of DMDBS on nucleation of high-pressure crystallization of iPP. iPP with 0.2–1.0 wt.% of the DMDBS was crystallized under elevated pressure, up to 300 MPa, in various thermal conditions, and then analyzed by PLM, WAXD, SEM, and DSC. During cooling, crystallization temperatures (Tc) were determined. It was found that under high-pressure DMDBS nucleated crystallization of iPP in the orthorhombic γ- form. As a consequence, Tc and the γ- form content increased for the nucleated iPP, while the size of polycrystalline aggregates decreased, although the effects depended on DMDBS content. The significant increase of Tc and the decrease of grain size under high pressure of 200–300 MPa required higher content of DMDBS than the nucleation of the α-form under lower pressure, possibly due to the effect of pressure on crystallization of DMDBS itself, which is a prerequisite for its nucleating activity.

High-pressure induced formation of isotactic polypropylene mesophase: Synergistic effect of pressure and pressurization rate

2018 ◽  
Vol 59 (3) ◽  
pp. 439-446 ◽  
Author(s):  
Jingjing Huang ◽  
Xiaobo Fu ◽  
Chunguang Shao ◽  
Zhe Ma ◽  
Yaming Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
Synergistic Effect ◽  
Isotactic Polypropylene ◽  
Effect Of Pressure ◽  
Pressurization Rate

scholarly journals High-pressure crystallization of isotactic polypropylene droplets

2012 ◽  
Vol 290 (16) ◽  
pp. 1599-1607 ◽  
Author(s):  
Kinga Zapala ◽  
Ewa Piorkowska ◽  
Anne Hiltner ◽  
Eric Baer
Keyword(s):  
High Pressure ◽  
Isotactic Polypropylene ◽  
Pressure Crystallization

High-pressure Food Processing

2008 ◽  
Vol 14 (5) ◽  
pp. 413-418 ◽  
Author(s):  
V.M. Balasubramaniam ◽  
D. Farkas
Keyword(s):  
High Pressure ◽  
Thermal Conditions ◽  
Nutrient Content ◽  
Elevated Pressure ◽  
High Pressure Processing ◽  
Heat Processing ◽  
Bacterial Inactivation ◽  
Indicator Organisms ◽  
Heat Pasteurization ◽  
Shelf Stable

High pressure processing (HPP) of foods offers a commercially viable and practical alternative to heat processing by allowing food processors to pasteurize foods at or near room temperature. Pressure in combination with moderate temperature also seems to be a promising approach for producing shelf-stable foods. This paper outlines research needs for further advancement of high pressure processing technology. Kinetic models are needed for describing bacterial inactivation under combined pressure-thermal conditions and for microbial process evaluation. Further, identification of suitable surrogate organisms are needed for use as indicator organisms and for process validation studies. More research is needed to evaluate process uniformity at elevated pressure-thermal conditions to facilitate successful introduction of low-acid shelf-stable foods. Combinations of non-thermal technologies with high pressure could reduce the severity of the process pressure requirement. Likewise, processing equipment requires improvements in reliability and line-speed to compete with heat pasteurization lines. More studies are also needed to document the changes in animal and vegetable tissue and nutrient content during pressure processing, from types of packaging, and from storage.

scholarly journals Periodicity and its breaking in compressed ferroelectric dabco monosalts

2014 ◽  
Vol 70 (a1) ◽  
pp. C265-C265 ◽  
Author(s):  
Anna Olejniczak ◽  
Andrzej Katrusiak
Keyword(s):  
High Pressure ◽  
Phase Ii ◽  
Elevated Pressure ◽  
Phase Iii ◽  
Environment Friendly ◽  
Practical Applications ◽  
Linear Chains ◽  
Ferroelectric Relaxors ◽  
Weak Hydrogen Bonds ◽  
Pressure Crystallization

1,4-Diazabicyclo[2.2.2]octane (dabco) monosalts form a fascinating group of compounds, which exhibit exceptional dielectric properties. They can be described by a general formula: dabcoHX, where X= Br-, I-, ClO4-, BF4-and ReO4-. DabcoHI is the first material for which anisotropic relaxor properties were reported.[1] The ferroelectric relaxors are particularly desired for numerous practical applications in electronics, including miniature electronic devices and new methods of storing electricity in capacitors. Moreover, organic relaxors are environment friendly and easier to produce and to dispose off, than inorganic ceramic relaxors of mixed perovskites and doped with lead. DabcoHI undergoes a large number of transformations at elevated pressure and temperature, however analogous dabcoHBr exists only in three forms. Exceptionally rich phase diagram of ten phases was also revealed for dabcoHClO4. At normal conditions in dabco monosalts the dabcoH+cations are NH+···N bonded into linear chains, but pressure can considerably modify that pattern, and the weak hydrogen bonds are relevant for the formation of new polymorphs at high pressure.[2,3] In all dabcoHI polymorphs the NH+···N bonded chains of dabcoH+cations are retained, however the chains are linear at 0.1 MPa and high pressure induces modulation of the chain with gradually increased periodicity. In dabcoHBr only phase III is NH+···N bonded. Although phase II of dabcoHClO4isostructural with phase II of dabcoHBF4, it behaves differently on lowering temperature than it was observed in dabcoHBF4. The polymorphic structures of dabco salts differ mainly in the arrangement of the chains and iodide anions, in the dabco conformation, and in the location of protons. When crystallized from methanol, above 1.70 GPa, dabcoHI forms solvates, and the high-pressure crystallization from aqueous solution leads to hydration already at 0.50 GPa.

Properties of nanocomposites based on isotactic polypropylene and high-pressure polyethylene with metal-containing nanofillers

2020 ◽  
pp. 59-64
Author(s):  
N. I. Kurbanova ◽  
◽  
T. M. Gulieva ◽  
N. Ya. Ischenko ◽  
◽  
...  
Keyword(s):  
High Pressure ◽  
Synergistic Effect ◽  
Polymer Matrix ◽  
Isotactic Polypropylene ◽  
Rheological Parameters ◽  
Mechanochemical Method ◽  
X Ray ◽  
Effect Of Additives ◽  
High Pressure Polyethylene ◽  
Properties Of Composites

The effect of additives of nanofillers (NF) containing nanoparticles (NP) of copper oxide, stabilized by a polymer matrix of maleized polyethylene (MPE), obtained by the mechanochemical method, on the properties of composites based on isotactic polypropylene (PP) and high-pressure polyethylene (PE) was studied by X-ray phase (XRD) and thermogravimetric (TGA) analyzes. The enhancement of strength, deformation, and rheological parameters, as well as the thermo-oxidative stability of the obtained nanocomposites was revealed, which, apparently, is due to the synergistic effect of the interaction of copper-containing nanoparticles with anhydride groups of MPE. It is shown that nanocomposites based on PP/PE/NF can be processed both by pressing and injection molding and extrusion, which expands the scope of its application.

scholarly journals The effect of high pressure treatment on the quality of chicken breast meat

2020 ◽  
Vol 14 (3-4) ◽  
pp. 76-81
Author(s):  
Nives Marušić Radovčić ◽  
Damir Ježek ◽  
Ksenija Markov ◽  
Jadranka Frece ◽  
Duška Ćurić ◽  
...  
Keyword(s):  
High Pressure ◽  
Treatment Time ◽  
Elevated Pressure ◽  
Quality Parameters ◽  
High Pressure Processing ◽  
Chicken Breast ◽  
Moisture Uptake ◽  
Breast Meat ◽  
Chicken Breast Meat ◽  
Cooking Yield

In the present work, the effect of high pressure processing (HPP) (0, 100, 200 and 300 MPa) and different treatment time (5 and 10 minutes) on the moisture uptake, cooking yield, colour and texture, as well as microbial population of chicken breast fillets was investigated. The application of high hydrostatic pressure resulted in a modification of quality parameters of chicken breast meat. By increasing pressure and time of the treatment the moisture uptake was reduced: samples treated with 300 MPa for 10 min had the lowest moisture uptake values. Cooking yield was not affected by HPP treatments. Increased pressure affected the colour by increasing L*, a* and b* values (only HPP treatment of 100 MPa in duration of 5 and 10 minutes did not affect colour of chicken breast meat). Lower pressures (100 and 200 MPa) tenderized, whereas elevated pressure (300 MPa) increased hardness in chicken breast fillets. Higher level of pressure (300 MPa) reduced bacteria count by about 3.0 – 5.3 log (CFU/g), depending on the microorganism and duration of the process.

scholarly journals Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

2015 ◽  
Vol 11 ◽  
pp. 576-582 ◽  
Author(s):  
Grzegorz Mlostoń ◽  
Paulina Grzelak ◽  
Maciej Mikina ◽  
Anthony Linden ◽  
Heinz Heimgartner
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
Thermal Conditions ◽  
Alder Reaction ◽  
Diels Alder ◽  
Hydrogen Shift ◽  
Diels Alder Reaction ◽  
Shift Sequence

Selected hetaryl and aryl thioketones react with acetylenecarboxylates under thermal conditions in the presence of LiClO4 or, alternatively, under high-pressure conditions (5 kbar) at room temperature yielding thiopyran derivatives. The hetero-Diels–Alder reaction occurs in a chemo- and regioselective manner. The initially formed [4 + 2] cycloadducts rearrange via a 1,3-hydrogen shift sequence to give the final products. The latter were smoothly oxidized by treatment with mCPBA to the corresponding sulfones.

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