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CRYSTALLIZATION CHARACTERISTICS OF β-PHASE CRYSTALS IN COPOLYMERS OF POLYPROPYLENE WITH LOW ETHYLENE CONTENT

Chinese Journal of Polymer Science 2001年第3期19卷 317-322页

作者： Wen-tao Hao Yi-yong He xiao-lie Luo De-zhu Ma Department of Polymer Science and Engineering University of Science and Technology of China Hefei 230026 China 中国科学技术大学安徽合肥

Polypropylene copolymers (CPP) containing β-nucleating agent were investigated by differential scanningcalorimetry (DSC), wide-angle x-ray diffraction (WAxD) and polarizing light microscopy (PLM). The results show thathigh content of β-phase crystals can also be formed for CPPs. Like PP homopolymers, the CPPs also have a most favorabletemperature near 132℃ for β-phase crystal growth. The crystallization rate of CPPs containing β-nucleating agent (β-CPP) ismuch greater than that of PP homopolymer containing β-nucleating agent (β-PP homopolymer). The observation ofspherulite morphology of β-CPP and β-PP homopolymer shows that the spherulites of β-CPP are more imperfect than thoseof β-PP homopolymer.

关键词： Copolymer polypropylene β-Nucleating agent Differential scanning calorimetry wide angle x-ray diffraction Spherulite

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Role of humidity on the structures and properties of regenerated silk fibers

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Progress in Natural Science:Materials International 2015年第5期25卷 430-436页

作者： Qingfa Peng Huili Shao xuechao Hu Yaopeng Zhang State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and Engineering Donghua University

Silk fiber was processed from highly concentrated spinning dope to solid fibers along with water removal. To understand the mechanism of water removal during silk fiber spinning process, a microfluidic chip was designed and applied to investigate the structures and mechanical properties of two kinds of regenerated silk fibroin fibers dry-spun at different relative humidity. The experimental results showed that the diameters of the fibers spun at 40% RH are always larger than the fibers spun at 50% RH due to different removal rates of water. The fibers spun at low humidity contain more β-sheet structure and lower degree of chain orientation and crystalline orientation. These results indicate that the fast phase transition of silk fibroin from sol–gel to silk fiber undergoes with rapid water removal and higher fiber orientation relates to more residue water and drawing force.

关键词： Dry spinning Relative humidity Biomimetic Regenerated silk fibroin wide angle x-ray diffraction

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The Influence of Additives on Crystallization of Polyvinyl Chloride

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Journal of Wuhan University of Technology(Materials Science) 2007年第2期22卷 271-275页

作者：刘亚群张超灿 Institute of Materials Science and Engineering Wuhan University of Technology

Acetanilide, adipic acid and potassium hydrogen phthalate were chosen as nucleating agents of polyvinyl chloride（PVC）, and their effects on PVC crystallization were studied by differential scanning calorimetry, wide angle x-ray diffraction and fourier transform infrared spectroscopy. The experimental results indicate that all of the three additives are compatible with PVC to some extent, but adipic acid＇s compatibility with PVC is less satisfactory. The three additives can improve PVC crystallinity, and acetanilide can decrease PVC glass transition temperature（T）and narrow PVC melting range, while adipic acid and potassium hydrogen phthalate rise T of PVC and widen its melting range. All additives do not affect PVC crystal system and all g samples are in orthorhombic system. All additives can improve （200）, （110）, （210） and （201, 111） planes growing. Moreover, acetanilide and adipic acid can shrink PVC spacings and improve the crystal perfection of PVC, but potassium hydrogen phthalate swells spacings and reduces the perfection of PVC crystal.

关键词： polyvinyl chloride crystalline structure differential scanning calorimetry wide angle x-ray diffraction

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A Constitutive Modeling and Experimental Effect of Shock Wave on the Microstructural Sub-strengthening of Granular Copper

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Journal of Metallic Material Research 2021年第1期4卷 19-25页

作者： A.D.Sharma A.K.Sharma N.Thakur Department of Physics Government College ChowariChamba176302India Om Sterling Global University-Hisar Haryana125001India Department of Physics Himachal Pradesh UniversityShimla171005India

Micro-sized copper powder(99.95%;O≤0.3)has been shock-processed with explosives of high detonation velocities of the order of 7.5 km/s to observe the structural and microstructural *** shock-consolidation technique has been used to obtain conglomerates of granular *** technique involves the cylindrical compaction system wherein the explosive-charge is in direct proximity with the powder whereas the other uses indirect shock pressure with die-plunger *** simulations have been performed on with Eulerian code *** simulated results show a good agreement with the experimental observation of detonation parameters like detonation velocity,pressure,particle velocity and shock pressure in the reactive media.A pin contactor method has been utilized to calculate the detonation pressure *** angled x-ray diffraction studies reveal that the crystalline structure(FCC)of the shocked specimen matches with the un-shocked *** emissive scanning electron microscopic examination of the compacted specimens show a good sub-structural strengthening and complement the theoretical *** diffraction based particle size analyzer also points towards the reduced particle size of the shock-processed specimen under high detonation ***-hardness tests conducted under variable loads of 0.1 kg,0.05 kg and 0.025 kg force with diamond indenter optical micrographs indicate a high order of micro-hardness of the order of 159 *** pycnometry used for the density measurement of the compacts shows that a compacted density of the order of 99.3%theoretical mean density has been achieved.

关键词： Shock waves wide angle x-ray diffraction Microstructure FE-SEM Laser diffraction Microhardness

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