The Effect of Cooling Rate during Crystallization on the Melting Behavior of Polypropylenes of Different Chemical Structure

2016 ◽  
Vol 10 (4) ◽  
pp. 479-483
Author(s):  
Yulia Lukanina ◽  
◽  
Anatoliy Khvatov ◽  
Natalya Kolesnikova ◽  
Anatoliy Popov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Maleic Anhydride ◽  
Optical Microscopy ◽  
Cooling Rate ◽  
Chemical Structure ◽  
Chemical Nature ◽  
Main Chain ◽  
Crystallization Rate ◽  
Melting Behavior ◽  
Random Copolymers

The melting behavior of polypropylenes of different chemical structure (isotactic homopolypropylene, propylene-based block and random copolymers and maleic anhydride grafted polypropylene) was studied by differential scanning calorimeter (DSC) and optical microscopy. Melting behavior and the crystal structure of polypropylene and its copolymers were observed depending on the crystallization rate, chemical nature of co-monomer unites and regularity of co-monomer units arrangement in the polypropylene main chain.

Microstructure and Properties of a Non-Quenched Prehardened Steel at Different Cooling Rate

2012 ◽  
Vol 524-527 ◽  
pp. 1976-1979
Author(s):  
Yi Luo ◽  
Jin Ming Peng
Keyword(s):  
Mechanical Properties ◽  
Fine Structure ◽  
Optical Microscopy ◽  
Cooling Rate ◽  
Retained Austenite ◽  
Transformation Products ◽  
Electronic Microscopy ◽  
Transmission Electronic Microscopy ◽  
Microstructure And Properties ◽  
Cooling Conditions

Mechanical properties of non-quenched prehardened (NQP) steel air cooled and sand cooled after forged were tested and their microstructure was investigated by optical microscopy and transmission electronic microscopy(TEM). The results show that mechanical properties of the NQP steel are similar at both cooling conditions, and their microstructure is bainite, whose fine structure is main bainite ferrite laths, retained austenite films, retained austenite islands and their transformation products. Bainite ferrite laths of the NQP steel air cooled are narrower than that sand cooled, while more retained austenite islands exist in latter.

scholarly journals The extracellular matrix of Volvox carteri: molecular structure of the cellular compartment.

1989 ◽  
Vol 109 (6) ◽  
pp. 3493-3501 ◽  
Author(s):  
H Ertl ◽  
R Mengele ◽  
S Wenzl ◽  
J Engel ◽  
M Sumper
Keyword(s):  
Extracellular Matrix ◽  
Chemical Structure ◽  
Chemical Nature ◽  
Sulfated Polysaccharide ◽  
Surface Glycoprotein ◽  
Amino Acid Residues ◽  
Volvox Carteri ◽  
Cellular Compartment ◽  
Cross Links ◽  
Cellular Compartments

The extracellular matrix (ECM) of Volvox contains insoluble fibrous layers that surround individual cells at a distance to form contiguous cellular compartments. Using immunological techniques, we identified a sulfated surface glycoprotein (SSG 185) as the monomeric precursor of this substructure within the ECM. The primary structure of the SSG 185 poly-peptide chain has been derived from cDNA and genomic DNA. A central domain of the protein, 80 amino acid residues long, consists almost exclusively of hydroxyproline residues. The chemical structure of the highly sulfated polysaccharide covalently attached to SSG 185 has been determined by permethylation analysis. As revealed by EM, SSG 185 is a rod-shaped molecule with a 21-nm-long polysaccharide strand protruding from its central region. The chemical nature of the cross-links between SSG 185 monomers is discussed.

The crystal structure of maleic anhydride

1962 ◽  
Vol 15 (1) ◽  
pp. 35-41 ◽  
Author(s):  
R. E. Marsh ◽  
E. Ubell ◽  
H. E. Wilcox
Keyword(s):  
Crystal Structure ◽  
Maleic Anhydride

scholarly journals The Effect of WS2 Nanosheets on the Non-Isothermal Cold- and Melt-Crystallization Kinetics of Poly(l-lactic acid) Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2214
Author(s):  
Mohammed Naffakh ◽  
Pablo Rica ◽  
Carmen Moya-Lopez ◽  
José Antonio Castro-Osma ◽  
Carlos Alonso-Moreno ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Transition Metal Dichalcogenides ◽  
Crystallization Rate ◽  
Melting Behavior ◽  
Hybrid Nanocomposites ◽  
Melt Crystallization ◽  
Heating Rates ◽  
Solution Blending ◽  
New Perspective ◽  
Ws2 Nanosheets

In the present work, hybrid nanocomposite materials were obtained by a solution blending of poly(l-lactic acid) (PLLA) and layered transition-metal dichalcogenides (TMDCs) based on tungsten disulfide nanosheets (2D-WS2) as a filler, varying its content between 0 and 1 wt%. The non-isothermal cold- and melt-crystallization and melting behavior of PLLA/2D-WS2 were investigated. The overall crystallization rate, final crystallinity, and subsequent melting behavior of PLLA were controlled by both the incorporation of 2D-WS2 and variation of the cooling/heating rates. In particular, the analysis of the cold-crystallization behavior of the PLLA matrix showed that the crystallization rate of PLLA was reduced after nanosheet incorporation. Unexpectedly for polymer nanocomposites, a drastic change from retardation to promotion of crystallization was observed with increasing the nanosheet content, while the melt-crystallization mechanism of PLLA remained unchanged. On the other hand, the double-melting peaks, mainly derived from melting–recrystallization–melting processes upon heating, and their dynamic behavior were coherent with the effect of 2D-WS2 involved in the crystallization of PLLA. Therefore, the results of the present study offer a new perspective for the potential of PLLA/hybrid nanocomposites in targeted applications.

Non-Isothermal Crystallization Kinetics of Graphene Oxide-Carbon Nanotubes Hybrids / Polyamide 6 Composites

2019 ◽  
Vol 41 (3) ◽  
pp. 394-394
Author(s):  
Zhi Qiang Wang Zhi Qiang Wang ◽  
Yong Ke Zhao and Xiang Feng Wu Yong Ke Zhao and Xiang Feng Wu
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Cooling Rate ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Polyamide 6 ◽  
Degree Of Crystallinity ◽  
Isothermal Crystallization Kinetics ◽  
Kinetics Of

The hybrids combined by nano-materials with different dimensions usually possess much better enhancement effects than single one. Graphene oxide-carbon nanotubes hybrids / polyamide 6 composites has been fabricated. The non-isothermal crystallization kinetics of the as-prepared samples was discussed. Research results showed that increasing the cooling rate was in favor of increasing the crystallization rate and the degree of crystallinity for the as-prepared samples. Moreover, the crystallization rate was first decreased and then increased with increasing the hybrids loading. Furthermore, the crystallization mechanism was changed with increasing the crystallization temperature and the cooling rate. The nucleation and growth modes of the non-isothermal crystallization could be classified into three different types, according to the Ozawa’s theory. These complicated results could be attributed to the important role of crystallization rate as well as the simultaneous hindering and promoting effects of the as-prepared hybrids. This work has reference values for understanding the crystallization kinetics of the polyamide 6-based composites.

Microstructure and Melting Behavior of Rapid Solidified Au-Ag-Ge Alloy

2012 ◽  
Vol 531-532 ◽  
pp. 618-622
Author(s):  
Da Tian Cui ◽  
Wen Hui Liu ◽  
Long Fei Liu
Keyword(s):  
Grain Boundaries ◽  
Cooling Rate ◽  
Melt Spinning ◽  
Melting Behavior ◽  
Exothermic Peak ◽  
Minimum Size ◽  
Thickness Direction ◽  
Liquid Temperature ◽  
Alloy Ingot ◽  
Precipitated Phase

Rapid solidified Au-Ag-Ge alloy was prepared by the melt spinning method，microstructure and melting behavior of the rapid solidified alloy was investigated by means of SEM, TEM and DSC. DSC results show that liquid temperature of the rapid solidified alloy is about 3～4°C lower than that of the alloy ingot, melting interval is also smaller. Minimum size of 40nm nanocrystalline has formed when the cooling rate is 1.293×106K/sec. Metastable supersaturated precipitated Ge-rich phases have been found at the grain boundaries, a structure mutation was found in the thickness direction of the rapid solidified alloy. Meanwhile, due to the stabilization transition of the supersaturated precipitated phase of the rapid solidified alloy, an exothermic peak has formed in the DSC curve, temperature of the exothermic peak becomes much lower when the cooling rate increases.

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