A STUDY OF RHEOLOGICAL PROPERTIES OF MOLTEN POLYETHYLENE TEREPHTHALATE Part Ⅰ:Influence of Moisture Content on Melt Rheological Properties at Low Shear Rates
The influence of non-isothermal melt crystallization on thermal behavior and morphology of poly-L-lactide (PLLA) was investigated by differential scanning calorimetry (DSC), polarizing micrograph (POM), and scanning electron microscopy (SEM).
Polytitanocarbosilanes(PTC) with different C content were synthesized by polysilane(PS), polyvinyl chloride(PVC)and Ti(OBu) 4 . Si Ti C O fibers with the specific resistance of 10 3 Ω·cm~10 0 Ω·cm were produced after melt spinning, curing in air and sintering in high temperature.
The results indicated that N (p methylphenyl) N′ (2 pyridyl)urea started to melt at 153 ℃ and the melting peak located at 173.86 ℃. The melting enthalpy is 204.45 kJ·mol-1. The decomposition peak of N (p methylphenyl) N′ (2 pyridyl)urea was found at 226.11 ℃ from DSC curve.
The compound was observed to melt at(349.38±0.04) K. The molar enthalpy Δ_(fus)H_(m),and entropy of fusion,Δ_(fus)S_(m) of the compound were determined to be(34 279±10) J/mol,(98.13±0.05) J/(mol\5K),(respectively).
The X-ray diffraction results indicate that the melt-crystallized sample of polyamide 618 transforms from the triclinic unit cell to the pseudo-hexagonal phase in the range of 120-180°C.
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AFM-tip-induced crystallization of poly(ethylene oxide) melt droplets
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The AFM-tip-induced crystallization of poly(ethylene oxide) (PEO) melt droplets was studied.
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The melt droplets with a height of 50-100 nm and a lateral size of 2-3 μm were obtained by melting the PEO ultra-thin films on a mica surface.
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In contrast, under AFM nanoindentation mode, the tip-induced crystallization occurred when a sufficiently high vertical tip force was applied to the melt droplets of PEO with Mn ? 1.0 × 104 g/mol.
A simplified volumetric method for the determination of sulfur in organic compounds is described. The results obtained by this method are in agreement with those obtained by the gravimetric method, The method is stated as following: Weigh accurately a sample containing 30—75 mg SO_4~- into a nickel crucible containing 1 g. of KNO_3 and 8 g. of KOH. Heat the crucible carefully with a small flame until the contents melt, increase the heat gradually until the decomposition is complete. Leach the melt...
The relationship between the melt index, the tensile strength and the stress-crack resistance, and that between the end-group structure and thermal stability of copo-lymer of tetrafluoroethylene and hexafluoropropylene have been studied. It was shown that: (1) Within a definite copolymer composition and molecular weight distribution, the relationship between the melt index and the tensile strength of the copolymer can be expressed by the empirical equation: F= 350-18.3 (MI); (2) The copolymer wi...
When polypropylene is compounded with 0.01%-0.1% 4-hydroxy 2,2, 6, 6-tetra-methyl-piperidine-1-oxyl, the rheological properties of the melt of polypropylene are modified, so that the temperature of spinning can be lowered from 330℃ to 280℃ and the fiber obtained has a tenacity of 5g/d.