Fractionation of lignosulfonates: comparison of ultrafiltration and ethanol solubility to obtain a set of fractions with distinct properties

Holzforschung ◽  
2015 ◽  
Vol 69 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Antoine Duval ◽  
Sonia Molina-Boisseau ◽  
Christine Chirat
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermal Degradation ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Groups ◽  
Incomplete Removal ◽  
Phenolic Hydroxyl Groups

Abstract Commercial lignosulfonates (LS), recovered from bisulfite pulping processes, are known for their wide polydispersity. In this study, LS were fractionated by ultrafiltration (UF) and based on their solubility in ethanol (EtOH) solutions. The combination of both methods leads to a set of fractions of varying properties, suitable for several applications. UF gives well-separated fractions, with low polydispersity, and increasing functionality (sulfonate and phenolic hydroxyl groups) with decreasing molecular weight (MW). EtOH solubility yields more polydisperse fractions but still appears to be an easy and rapid way to obtain fractions with increasing MW. The residual sugars in LS, resulting from incomplete removal of hemicelluloses, were found to be mainly in the form of low MW oligomers, which were not bound chemically to lignin. Thermal degradation of the different fractions was also compared, giving better comprehension of the influence of the structure and composition. A glass transition temperature (Tg) could be measured for some fractions and was correlated to their MW.

Imide Oligomers Containing Pendent and Terminal Phenylethynyl Groups—II

1998 ◽  
Vol 10 (3) ◽  
pp. 273-283 ◽  
Author(s):  
J W Connell ◽  
J G Smith ◽  
P M Hergenrother
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Average Molecular Weight ◽  
Adhesive Tape ◽  
High Glass Transition Temperature ◽  
Compressive Properties ◽  
Compression Moulding ◽  
Imide Oligomers

As part of a programme to develop high-performance/high-temperature structural resins for aeronautical applications, imide oligomers containing pendent and terminal phenylethynyl groups were prepared, characterized and the cured resins evaluated as composite matrices. The oligomers were prepared at a calculated number-average molecular weight of 5000 g mol−1 and contained 15–20 mol% pendent phenylethynyl groups. In previous work, an oligomer containing pendent and terminal phenylethynyl groups exhibited a high glass transition temperature (∼313 °C), and laminates therefrom exhibited high compressive properties, but processability, fracture toughness, microcrack resistance and damage tolerance were less than desired. In an attempt to improve these deficiencies, modifications in the oligomeric backbone involving the incorporation of 1,3-bis(3-aminophenoxy)benzene were investigated as a means of improving processability and toughness without detracting from the high glass transition temperature and high compressive properties. The amide acid oligomeric solutions were prepared in N-methyl-2-pyrrolidinone and were subsequently processed into imide powder, thin films, adhesive tape and carbon fibre prepreg. Neat resin plaques were fabricated from imide powder by compression moulding. The maximum processing pressure was 1.4 MPa and the cure temperature ranged from 350 to 371 °C for 1 h for the mouldings, adhesives, films and composites. The properties of the 1,3-bis(3-aminophenoxy)benzene modified cured imide oligomers containing pendent and terminal phenylethynyl groups are compared with those of previously prepared oligomers containing pendent and terminal phenylethynyl groups of similar composition and molecular weight.

scholarly journals Triple-Shape Memory Behavior of Modified Lactide/Glycolide Copolymers

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2984
Author(s):  
Anna Smola-Dmochowska ◽  
Natalia Śmigiel-Gac ◽  
Bożena Kaczmarczyk ◽  
Michał Sobota ◽  
Henryk Janeczek ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Hydroxyl Groups ◽  
Butylene Succinate ◽  
Shape Memory Behavior ◽  
Triple Shape Memory ◽  
High Flexibility ◽  
Bioresorbable Implants

The paper presents the formation and properties of biodegradable thermoplastic blends with triple-shape memory behavior, which were obtained by the blending and extrusion of poly(l-lactide-co-glycolide) and bioresorbable aliphatic oligoesters with side hydroxyl groups: oligo (butylene succinate-co-butylene citrate) and oligo(butylene citrate). Addition of the oligoesters to poly (l-lactide-co-glycolide) reduces the glass transition temperature (Tg) and also increases the flexibility and shape memory behavior of the final blends. Among the tested blends, materials containing less than 20 wt % of oligo (butylene succinate-co-butylene citrate) seem especially promising for biomedical applications as materials for manufacturing bioresorbable implants with high flexibility and relatively good mechanical properties. These blends show compatibility, exhibiting one glass transition temperature and macroscopically uniform physical properties.

Properties of Hyperbranched Polyglycidol’s Derivatives

2020 ◽  
Vol 869 ◽  
pp. 190-195
Author(s):  
Yuri Mikhailov ◽  
Ludmila Romanova ◽  
Anna Darovskikh ◽  
Nilson Garifullin
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Functional Groups ◽  
Enthalpy Of Formation ◽  
Rheological Parameters ◽  
Weight Composition ◽  
Composition And Structure

Some properties (enthalpy of formation, glass transition temperature and rheological parameters) of hyperbranched polyglycidol derivatives containing nitrate and azide functional groups were investigated. The dependence of the found properties on the molecular weight, composition and structure of the investigated substances was determined.

Effects of moisture content, molecular weight, and crystallinity on the glass transition temperature of inulin

2011 ◽  
Vol 83 (2) ◽  
pp. 934-939 ◽  
Author(s):  
Kiyoshi Kawai ◽  
Ken Fukami ◽  
Pariya Thanatuksorn ◽  
Chotika Viriyarattanasak ◽  
Kazuhito Kajiwara
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Moisture Content
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