Degradation of PBS Introducing Crosslink by Glycerol

2014 ◽  
Vol 934 ◽  
pp. 104-109
Author(s):  
Er Juan Zhi ◽  
Li Gao ◽  
Ping Li Wang ◽  
Jun Hui Ji
Keyword(s):  
Crystal Structure ◽  
Polymer Chain ◽  
Amorphous Region ◽  
Aliphatic Chain ◽  
Sequence Distribution ◽  
Crystal Region

A series of poly (butylenes succinate) with low Glycerol (GL) fraction ranging from 0 to 6‰ were synthesized by two step melting condensation. By this method, some three-dimentional branch or crosslink structure was introduced to the linear aliphatic chain of PBS. The sequence distribution, GL fraction, crystal structure and degradability were investigated. The degrability of PBS enhanced when GL was led into polymer chain as the crystalline (χc) decreased with GL increasing. And the degradation first happened in amorphous region and then crystal region.

scholarly journals Changes in Crystal Structure and Accelerated Hydrolytic Degradation of Polylactic Acid in High Humidity

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4324
Author(s):  
Yutaka Kobayashi ◽  
Tsubasa Ueda ◽  
Akira Ishigami ◽  
Hiroshi Ito
Keyword(s):  
Crystal Structure ◽  
Polylactic Acid ◽  
Hydrolytic Degradation ◽  
Gel Permeation Chromatography ◽  
Amorphous Region ◽  
Industrial Applications ◽  
Reduced Pressure ◽  
Specific Temperature ◽  
Time Changes ◽  
Random Scission

Highly crystallized polylactic acid (PLA) is suitable for industrial applications due to its stiffness, heat resistance, and dimensional stability. However, crystal lamellae in PLA products might delay PLA decomposition in the environment. This study clarifies how the initial crystal structure influences the hydrolytic degradation of PLA under accelerated conditions. Crystallized PLA was prepared by annealing amorphous PLA at a specific temperature under reduced pressure. Specimens with varied crystal structure were kept at 70 °C and in a relative humidity (RH) of 95% for a specific time. Changes in crystal structure were analyzed using differential calorimetry and wide-angle X-lay diffraction. The molecular weight (MW) was measured with gel permeation chromatography. The crystallinity of the amorphous PLA became the same as that of the initially annealed PLA within one hour at 70 °C and 95% RH. The MW of the amorphous PLA decreased faster even though the crystallinity was similar during the accelerated degradation. The low MW chains of the amorphous PLA tended to decrease faster, although changes in the MW distribution suggested random scission of the molecular chains for initially crystallized PLA. The concentrations of chain ends and impurities, which catalyze hydrolysis, in the amorphous region were considered to be different in the initial crystallization. The crystallinity alone does not determine the speed of hydrolysis.

N-(2-Pyridylcarbonyl)benzamide

2007 ◽  
Vol 63 (3) ◽  
pp. o1455-o1456 ◽  
Author(s):  
Gilles Gasser ◽  
Helen Stoeckli-Evans
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Polymer Chain ◽  
Title Compound ◽  
Phenyl Ring ◽  
Pyridine Ring ◽  
Axis Direction ◽  
Compound C ◽  
Phenyl Rings

The title compound, C13H10N2O2, has a Z,Z (trans–trans) arrangement of the central CONHCO group and an intramolecular N—H...N hydrogen bond. The molecule has a twisted conformation; the pyridine ring, which is almost parallel to the plane of the amide function at position 2, is inclined to the phenyl ring by 50.05 (6)°. In the crystal structure, symmetry-related molecules are linked by C—H...O hydrogen bonds, forming a zigzag polymer chain extending in the a-axis direction. The chains are linked by a C—H...π interaction involving phenyl rings of adjacent chains. There is also a π–π interaction involving pyridine rings related by a center of symmetry.

The Crystal Structure of catena-{μ-[2-Methyl-2-(phenylthio)propanoato-O,O′]-{tris-μ-[2-methyl-2 -(phenylthio)propanoato-O,O′]-dizinc(II)}}

1987 ◽  
Vol 40 (5) ◽  
pp. 981 ◽  
Author(s):  
WH Chan ◽  
TCW Mak ◽  
WH Yip ◽  
CHL Kennard ◽  
G Smith ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Polymer Chain ◽  
Carboxy Group ◽  
Polymer Structure ◽  
Carboxylate Ligand ◽  
Propanoic Acid ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Linear Polymer Chain

.The crystal structure of the anhydrous zinc(11) complex of 2-methyl-2-(phenylthio) propanoic acid, with formula [Zn2(C10H12O2)4]n, has been determined by X-ray diffraction at 20�C and refined to a residual R 0.041 for 2885 observed reflections. Crystals are monoclinic, space group P 21, with two diper units of the polymer in a unit cell with dimensions a 12.710(4), b 13.760(2), c 12.699(6) �, β 95.44(5)�. The polymer structure is based on a repeating tris -carboxylate-bridged dimer unit with each zinc centre tetrahedral [Zn-O (mean) 1.958(5) �, Zn-Zn 3.393(2) �]. The dimer is extended into a linear polymer chain by an O,O' bridge through the carboxy group of the fourth carboxylate ligand.

TEM Observation of Defect Structure of Low-Energy Ion Implanted SiC

2014 ◽  
Vol 778-780 ◽  
pp. 350-353 ◽  
Author(s):  
Toshimasa Kameda ◽  
Atsuo Tomita ◽  
Takaaki Matsui ◽  
Toshiyuki Isshiki
Keyword(s):  
Crystal Structure ◽  
Defect Structure ◽  
Amorphous Region ◽  
Low Energy ◽  
Ion Concentration ◽  
Poly Type ◽  
Ion Implanted

The aim of this review is to present the observation of low-energy ion implanted SiC and annealing them by using TEM. By detail analyses of the TEM images and results of SRIM, ion implanted SiC was classification four structure depending on the ion concentration in a few ten nm shallow region. This results suggest that crystal structure in a few nm shallow region can be controled by concentration of the ion implant. And SiC was re-crystallized single poly-type after annealed at 1500°C. But, defects in end of amorphous region affect to recover the damaged structure .

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