scholarly journals Synthesis and properties of shape memory polyurethanes generated from schiff-base chain extender containing benzoyl and pyridyl rings

2018 ◽  
Vol 21 (1) ◽  
pp. 55-63 ◽  
Author(s):  
Neng-Chiao Weng ◽  
Chih-Fu Wu ◽  
Wen-Chin Tsen ◽  
Cheng-Lung Wu ◽  
Maw-Cherng Suen
Keyword(s):  
Schiff Base ◽  
Shape Memory ◽  
Chain Extender

Highly Cross-Linked and Stable Shape-Memory Polyurethanes Containing a Planar Ring Chain Extender

2020 ◽  
Vol 2 (11) ◽  
pp. 5259-5268
Author(s):  
Qing Luo ◽  
Jing Chen ◽  
Pitchaimari Gnanasekar ◽  
Xiaozhen Ma ◽  
Dongdong Qin ◽  
...  
Keyword(s):  
Shape Memory ◽  
Chain Extender ◽  
Stable Shape

Structure–properties relationship of the polyurethanes that contain Schiff base in the main chain

2020 ◽  
Vol 32 (7) ◽  
pp. 784-792
Author(s):  
Stefan Oprea ◽  
Violeta Otilia Potolinca ◽  
Veronica Oprea ◽  
Livia Ingrid Diaconu
Keyword(s):  
Schiff Base ◽  
Main Chain ◽  
Raw Materials ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Chain Extender ◽  
Cross Linking ◽  
Practical Applications ◽  
Molar Ratios ◽  
A Chain

This article studies the diversification of useful properties of polyurethane (PU) structures by the inclusion of new components. PUs containing a Schiff base in the main chain were synthesized by using N, N′-bis(salicylidene)-1,3-propanediamine as a chain extender. Novel Schiff base PUs were synthesized via a two-step polymerization starting from a Schiff base derivative diol chain extender with different molar ratios or by cross-linking with various natural raw materials. The sought after structures was confirmed by Fourier transform infrared spectra that showed the disappearance of the signals of both the hydroxyl and isocyanate groups. The thermal properties of these PUs were investigated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The initial degradation temperatures of the obtained PUs were found to be in the range of 300–350°C. Based on the results from DMA, the rigid structure of the Schiff base from the backbone of the PUs presented a higher storage modulus, results which may be connected to the physical cross-linking process of the macromolecules. Their optical properties were determined by fluorescence spectroscopy. The incorporation of Schiff base structures into the main PU chain generates new PU structures with improved thermomechanical properties, which includes possible bioactive Schiff base moieties, widening the range of practical applications for such polymers.

The Effect of Chain Extender Type on the Physical, Mechanical, and Shape Memory Properties of Poly(ε-Caprolactone)-based Polyurethane-ureas

2017 ◽  
Vol 56 (18) ◽  
pp. 1977-1985 ◽  
Author(s):  
Alireza Eyvazzadeh Kalajahi ◽  
Mostafa Rezaei ◽  
Farhang Abbasi ◽  
Gity Mir Mohamad Sadeghi
Keyword(s):  
Shape Memory ◽  
Chain Extender ◽  
Shape Memory Properties

Biodegradable shape memory polymers functionalized with anti-biofouling interpenetrating polymer networks

2016 ◽  
Vol 4 (32) ◽  
pp. 5394-5404 ◽  
Author(s):  
I. Dueramae ◽  
M. Nishida ◽  
T. Nakaji-Hirabayashi ◽  
K. Matsumura ◽  
H. Kitano
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Polymer Networks ◽  
Shape Memory Polymers ◽  
Chain Extender ◽  
Interpenetrating Polymer Networks ◽  
Hexamethylene Diisocyanate ◽  
Cross Linker ◽  
Copolymer Poly ◽  
Shape Memory Polyurethane

A novel type of shape memory polyurethane (SMPU) with high mechanical properties and biodegradability was constructed using a lactone copolymer (poly(ε-caprolactone-co-γ-butyrolactone), PCLBL), a diol- or triol-based chain extender (1,5-pentanediol, glycerol and 2-amino-2-hydroxymethyl-1,3-propanediol) and a diisocyanate cross-linker (1,6-hexamethylene diisocyanate).

Clay Reinforced Hyperbranched Polyurethane Nanocomposites Based on Palm Oil Polyol as Shape Memory Materials

2012 ◽  
Vol 548 ◽  
pp. 115-118 ◽  
Author(s):  
Ernie Suzana Ali ◽  
Syazana Ahmad Zubir ◽  
Ahmad Sahrim
Keyword(s):  
Shape Memory ◽  
Palm Oil ◽  
Chain Extender ◽  
Diphenylmethane Diisocyanate ◽  
Mixing Process ◽  
Clay Particles ◽  
Step Process ◽  
Hyperbranched Polyurethane ◽  
Shape Memory Properties ◽  
Polyurethane Nanocomposites

Reactive nanoclay reinforced hyperbranched polyurethane (HPU) nanocomposites have been synthesized with the introduction of palm oil polyol as part of the precursor. The HPU were prepared in a two-step process using polycaprolactonediol, 4,4’-diphenylmethane diisocyanate and 1,4-butanediol as chain extender. Nanoclay was added with the purpose of improving the properties of the pristine polyurethane. The introduction of palm oil polyol is believed to enhance the mixing process between polymer matrix and filler. Thermal, mechanical and shape memory properties of produced HPU were investigated. The results showed that the crystallinity of HPU nanocomposites decreased with introduction of clay particles and that the mechanical and shape memory properties were enhanced with the addition of small amount of reactive nanoclay (up to 3 wt%).

scholarly journals Effect of Nanofiller Dispersion on Morphology, Mechanical and Conducting Properties of Electroactive Shape Memory Poly(Urethane-Urea)/Functional Nanodiamond Composite

2015 ◽  
Vol 15 (4) ◽  
pp. 14-28 ◽  
Author(s):  
A. Kausar
Keyword(s):  
Electrical Conductivity ◽  
Tensile Strength ◽  
Shape Memory ◽  
Shape Recovery ◽  
Hard Segment ◽  
Soft Segment ◽  
Chain Extender ◽  
Solution Casting ◽  
Melt Blending ◽  
Solution Route

Abstract In this attempt, segmented poly(urethane urea) was prepared from polycaprolactone triol (soft segment), 1,3- bis(isocyanatomethyl)cyclohexane (hard segment) and 4,5-diaminophthalonitrile (chain extender). Acidfunctionalized nano-diamond was used as nano-filler. The nanocomposites were processed using solution casting and melt blending. Unique morphology was observed by SEM due to generation of crosslinked polyurethane and ND network. The s-PUU/ND 10 depicted 6 % increase in tensile strength compared with m-PUU/ND 10. 10 wt. % ND loading via solution route increased conductivity to 0.089 Scm-1 relative to m-PUU/ND 10 (0.057 Scm-1). Electrical conductivity of nanocomposites was enough to show electroactive shape recovery of 95 % (40 V).

Tensile Failure of 55-Nitinol Wire

1975 ◽  
Vol 33 ◽  
pp. 46-47
Author(s):  
F. I. Grace
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Stoichiometric Composition ◽  
Tensile Failure ◽  
Initial State ◽  
Initial Shape ◽  
Nitinol Wire ◽  
Cscl Type ◽  
Shear Transformation

An interest in NiTi alloys with near stoichiometric composition (55 NiTi) has intensified since they were found to exhibit a unique mechanical shape memory effect at the Naval Ordnance Laboratory some twelve years ago (thus refered to as NITINOL alloys). Since then, the microstructural mechanisms associated with the shape memory effect have been investigated and several interesting engineering applications have appeared.The shape memory effect implies that the alloy deformed from an initial shape will spontaneously return to that initial state upon heating. This behavior is reported to be related to a diffusionless shear transformation which takes place between similar but slightly different CsCl type structures.

TEM study of order, structure and defects of β and martensite in Cu-Al-Mn shape memory alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 188-189
Author(s):  
J.M. Guilemany ◽  
F. Peregrin
Keyword(s):  
Shape Memory ◽  
Orthophosphoric Acid ◽  
Isopropyl Alcohol ◽  
Metastable Phase ◽  
Characteristic Temperature ◽  
Ethanol Solution ◽  
Order Structure ◽  
Thin Foils ◽  
Polycrystalline Alloys ◽  
Diamond Saw

The shape memory effect (SME) shown by Cu-Al-Mn alloys stems from the thermoelastic martensitic transformation occuring between a β (L2,) metastable phase and a martensitic phase. The TEM study of both phases in single and polycrystalline Cu-Al-Mn alloys give us greater knowledge of the structure, order and defects.The alloys were obtained by vacuum melting of Cu, Al and Mn and single crystals were obtained from polycrystalline alloys using a modified Bridgman method. Four different alloys were used with (e/a) ranging from 1.41 to 1.46 . Two different heat treatments were used and the alloys also underwent thermal cycling throughout their characteristic temperature range -Ms, Mf, As, Af-. The specimens were cut using a low speed diamond saw and discs were mechanically thinned to 100 μm and then ion milled to perforation at 4 kV. Some thin foils were also prepared by twin-jet electropolishing, using a (1:10:50:50) urea: isopropyl alcohol: orthophosphoric acid: ethanol solution at 20°C. The foils were examinated on a TEM operated at 200 kV.

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