scholarly journals Synthesis of thermoplastic poly(ester-olefin) elastomers

2004 ◽  
Vol 58 (10) ◽  
pp. 444-449
Author(s):  
Branka Tanasijevic ◽  
Salem Elkhaseh ◽  
Marija Nikolic ◽  
Jasna Djonlagic
Keyword(s):  
Soft Segment ◽  
Weight Ratio ◽  
Soxhlet Extraction ◽  
Thermoplastic Elastomers ◽  
Molecular Structures ◽  
Degree Of Crystallinity ◽  
Molar Ratio ◽  
Mechanical Spectroscopy ◽  
Scanning Calorimetry ◽  
High Boiling Solvent

A series of thermoplastic poly(ester-olefin) elastomers, based on poly(ethylene-stat-butylene), HO-PEB-OH, as the soft segment and poly (butylene terephthalate), PBT, as the hard segment, were synthesized by a catalyzed transesterification reaction in solution. The incorporation of soft hydrogenated poly(butadiene) segments into the copolyester backbone was accomplished by the polycondensation of ?, ?-dihydroxyl telechelic HO-PEB-OH, (PEB Mn = 3092 g/mol) with 1,4-butanediol (BD) and dimethyl terephthalate (DMT) in the presence of a 50 wt-% high boiling solvent i.e., 1,2,4-trichlorobenzene. The molar ratio of the starting comonomers was selected to result in a constant hard to soft weight ratio of 60:40. The synthesis was optimized in terms of both the concentration of catalyst, tetra-n-butyl-titanate (Ti(OBu)4), and stabilizer, N,N'-diphenyl-p-phenylenediamine (DPPD), as well as the reaction time. It was found that the optimal catalyst concentration (Ti(OBu)4) for the synthesis of these thermoplastic elastomers was 1.0 mmol/mol ester and the optimal DPPD concentration was 1.0 wt-%. The extent of the reaction was followed by measuring the inherent viscosity of the reaction mixture. The effectiveness of the incorporation of the soft segments into the copolymer chains was proved by Soxhlet extraction with chloroform. The molecular structures, composition and the size of the synthesized poly(ester-butylene)s were verified by 1H NMR spectroscopy, viscometry of dilute solutions and the complex dynamic melt viscosity. The thermal properties of poly(ester-olefin)s were investigated by differential scanning calorimetry (DSC). The degree of crystallinity was also determined by DSC. The thermal and thermo-oxidative stability were investigated by thermogravimetric analysis (TGA). The rheological properties of poly(ester-olefin)s were investigated by dynamic mechanical spectroscopy in the melt and solid state.

scholarly journals Synthesis of thermoplastic poly(ester-siloxane)s in the melt and in solution

2005 ◽  
Vol 70 (12) ◽  
pp. 1469-1485 ◽  
Author(s):  
Biljana Dojcinovic ◽  
Vesna Antic ◽  
Marija Vuckovic ◽  
Jasna Djonlagic
Keyword(s):  
1H Nmr Spectroscopy ◽  
Hard Segment ◽  
Soft Segment ◽  
Weight Ratio ◽  
Thermoplastic Elastomers ◽  
Degree Of Crystallinity ◽  
Mechanical Spectroscopy ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
High Boiling Solvent

Two series of thermoplastic elastomers, based on poly(dimethylsiloxane) PDMS, as the soft segment and poly(butylene terephthalate), PBT, as the hard segment, were synthesized by catalyzed transesterification, from dimethyl terephthalate, DMT, silanol-terminated poly(dimethylsiloxane), PDMS-OH Mn=1750g/mol, and 1,4-butanediol, BD. The mole ratio of the starting comonomers was selected to result in a constant hard to soft weight ratio of 55:45. The first series was synthesized in order to determine the optimal mole ratio of BD and DMT for the synthesis of high molecular weight thermoplastic poly(ester-siloxane)s, TPESs. The second series was performed in the presence of the high-boiling solvent, 1,2,4-trichlorbenzene in order to increase the mixing between the extremely non-polar siloxane prepolymer and the polar reactants, DMT and BD, and, therefore, avoid phase separation during synthesis. The structure and composition of the synthesized poly(ester-siloxane)s were verified by 1H-NMR spectroscopy, while the melting temperatures and degree of crystallinity were determined by differential scanning calorimetry (DSC). The effectiveness of the incorporation of the silanol-terminated poly( dimethylsiloxane) into the polyester chains was verified by chloroform extraction. The rheological properties of the poly(ester-siloxane)s were investigated by dynamic mechanical spectroscopy (DMA).

Magnetic Properties of Irradiated Nickel Ferrite Thermoplastic Natural Rubber Nanocomposite

2014 ◽  
Vol 879 ◽  
pp. 206-212 ◽  
Author(s):  
Sivanesan Appadu ◽  
Sahrim Hj. Ahmad ◽  
Chantara Thevy Ratnam ◽  
Meor Yahaya Razali ◽  
Moayad Husein Flaifel ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Thermal Properties ◽  
Natural Rubber ◽  
Weight Ratio ◽  
Xrd Analysis ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Magnetic Microstructure ◽  
Sem Image ◽  
Thermoplastic Natural Rubber

The effect of electron beam (EB) irradiation at different doses on the magnetic, microstructure, morphological and thermal properties of NiFe2O4/Thermoplastic Natural Rubber (TPNR) nanocomposite was investigated. The NiFe2O4/TPNR nanocomposite samples were prepared by using a Haake mixer in weight ratio of 12:88. The TPNR matrix consists of natural rubber (NR), liquid natural rubber (LNR) and high density polyethylene (HDPE) in weight ratio of 20:10:70. The samples were irradiated using a 2 MeV EB machine in doses from 0 - 200 kGy. Magnetic properties studied by using the vibrating sample magnetometer (VSM) at room temperature showed that the values of saturation magnetization (MS), remanence magnetization (MR) and the coercivity (HC) value increased with increasing doses of irradiation. The increase in MSand MRvalues is attributed to the increase in concentration of Fe3+ions at octahedral B-site and decrease of concentration at the tetrahedral A-site in the NiFe2O4cubic structure. X-ray diffraction (XRD) analysis of the samples showed that peak intensities decreased and the width of the peaks increased with increasing doses of irradiation. Scanning electron microscope (SEM) image of the nanocomposite cross section showed the presence of defects which is more visible with increasing doses of irradiation. In the case of thermal properties, differential scanning calorimetry (DSC) analysis showed that the crystallization temperature (Tc) and the degree of crystallinity (Xc) of the nanocomposite samples decreased with increasing doses of irradiation due to crosslinking of polymeric chains which hinders the growth of crystals.

Synthesis and Characterization of IPDI Based Shape Memory Polyurethane

2020 ◽  
Vol 1010 ◽  
pp. 142-147
Author(s):  
Nur Athirah Rasli @ Rosli ◽  
Syazana Ahmad Zubir
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Soft Segment ◽  
Shape Memory Polymer ◽  
Palm Kernel ◽  
Hexamethylene Diisocyanate ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Chain Flexibility

Various polyurethane-based shape memory polymer was synthesized using polycaprolactone (PCL) as soft segment and, hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI) as the hard segments. Palm kernel oil-based polyol was used to replace part of the petroleum-based polyol due to the increasing demand on renewable resources as a result of environmental awareness. The synthesis has been carried out using two step polymerization method. The effects of varying the molar ratio of IPDI/HMDI on material properties such as crystallinity, transition temperature, morphology, shape memory effect and tensile strength were investigated by using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), shape memory test and tensile test. A high IPDI content in SMPU results in better shape memory effect, whereas increasing HMDI content leads to a better chain flexibility. In this work, the incorporation of IPDI contributes to the formation of phase separation which enhance the formation of crystalline soft segment structure while the incorporation of HMDI as isocyanate tend to promote phase mixing which enhance the chain flexibility of the SMPU backbone.

Effect of Poly(D-Lactic Acid)-co-Polyethylene Glycol on the Crystallization of Poly(L-Lactic Acid)

2017 ◽  
Vol 751 ◽  
pp. 283-289 ◽  
Author(s):  
Ployrawee Kaewlamyai ◽  
Amornrat Lertworasirikul
Keyword(s):  
Lactic Acid ◽  
Polyethylene Glycol ◽  
Weight Ratio ◽  
Crystallization Rate ◽  
Heat Stability ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Infrared Spectrometry ◽  
Scanning Calorimetry

Poly (lactic acid) (PLA) is a biopolymer derived from renewable resources and can be disposed of without creating harm to the environment. PLA can be formed by thermoplastic processes and has good mechanical properties. However, its disadvantages are a high crystallization temperature, slow crystallization rate, poor heat stability and low ductility. In the past, it was found that poly (D-lactic acid) (PDLA) can form complexes with poly (L-lactic acid) (PLLA) and the complexes could accelerate the crystallization and increase the degree of crystallinity of the PLA, but decrease the ductility. It is known that polyethylene glycol (PEG) can improve the ductility of PLLA. In this research, PDLA was copolymerized with PEG in an attempt to improve both crystallization behavior and ductility of PLLA. Poly (D-lactic acid)-co-polyethylene glycol (PDEG) was synthesized by ring opening polymerization using D-lactide and PEG at a D-lactide:PEG weight ratio of 10:3. The PDEG was blended with PLLA with a PDEG content of 0wt% to 50wt% by melt blending process. Fourier transform infrared spectrometry (FT-IR) and X-Ray diffractometry (XRD) confirmed the stereocomplex formation between PDEG and PLLA. Characterization by differential scanning calorimetry (DSC) revealed that crystallization temperatures of the blends were decreased in the presence of PDEG. Storage moduli and tan of the blends obtained from dynamic mechanical analysis (DMA) decreased as PDEG content increased. Polarized optical microscopy (POM) micrographs of blends with PDEG content of 1wt% to 5wt% obviously showed that crystallization rate was increased. PDEG has the potential to be an effective nucleating agent and efficient plasticizer for PLLA.

Preparation and Characterisation of Phase Change Material-Loaded Polyurea Microcapsules Several Hundred Micrometres in Diameter

2009 ◽  
Vol 17 (6) ◽  
pp. 365-369 ◽  
Author(s):  
Takayuki Takei ◽  
Masahiro Yoshida ◽  
Tomonori Nagayoshi ◽  
Yasuo Hatate ◽  
Kouichiro Shiomori ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Weight Ratio ◽  
Phenyl Isocyanate ◽  
Toluene Diisocyanate ◽  
Molar Ratio ◽  
Agitation Rate ◽  
Scanning Calorimetry ◽  
Water Emulsion ◽  
Change Material

In the present study, we attempted to prepare phase-change material (PCM)-loaded polyurea microcapsules several hundred micrometres in diameter via oil-in-water emulsion polymerisation. An oil phase with two types of isocyanate monomers (2,4-toluene diisocyanate (TDI) and phenyl isocyanate (PI)) and tetradecane as PCM was dispersed in an aqueous phase with hexamethylene diamine (HMD). The polyurea shell of microcapsules was formed by reaction of the isocyanate monomers with the amine groups derived from HMD and hydrolysed isocyanate monomers. A suitably adjusted agitation rate made it possible to prepare the required microcapsules. An increased molar ratio of TDI to PI in oil phase resulted in improvement of microcapsule morphology. Increased weight ratio of tetradecane to the two isocyanate monomers (TDI and PI) led to an increase in the PCM content in the microcapsules, which is preferable for practical applications. An examination using differential scanning calorimetry analyser demonstrated that the polyurea shell of the microcapsules scarcely influenced the thermal properties of encapsulated tetradecane.

scholarly journals Rheological behaviour of thermoplastic poly(ester-siloxane)s

2010 ◽  
Vol 64 (6) ◽  
pp. 537-545 ◽  
Author(s):  
Vesna Antic ◽  
Marija Pergal ◽  
Malisa Antic ◽  
Jasna Djonlagic
Keyword(s):  
Dynamic Viscosity ◽  
Microphase Separation ◽  
Soft Segment ◽  
Rheological Behaviour ◽  
Thermoplastic Elastomers ◽  
Degree Of Crystallinity ◽  
Mass Ratio ◽  
Complex Dynamic ◽  
Constant Length ◽  
Soft Segments

Two series of thermoplastic elastomers (TPES) based on poly(dimethylsiloxane), (PDMS) as the soft segment and poly(butylene terephthalate) (PBT) as the hard segment, were analyzed by dynamic mechanical spectroscopy. In the first TPES series the lengths of both hard and soft segments were varied while the mass ratio of the hard to soft segments was nearly constant (about 60 mass%). In the second series, the mass ratio of hard and soft segments was varied in the range from 60/40 to 40/60, with a constant length of soft PDMS segments. The influence of the structure and composition of TPESs on the rheological properties, such as complex dynamic viscosity, ?*, the storage, G?, and loss, G?, shear modulus as well as the microphase separation transition temperature, TMST, was examined. The obtained results showed that the storage modulus of the TPESs increased in a rubbery plateau region with increasing degree of crystallinity. The rheological measurements of TPESs also showed that a microphase reorganization occurred during the melting process. The microphase separation transition temperatures were in the range from 220 to 234 ?C. In the isotropic molten state, the complex dynamic viscosity increased with increasing both the content and lenght of hard PBT segments.

scholarly journals Enhanced Nanoencapsulation of Sepiapterin within PEG-PCL Nanoparticles by Complexation with Triacetyl-Beta Cyclodextrin

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2715 ◽  
Author(s):  
Nataliya Kuplennik ◽  
Alejandro Sosnik
Keyword(s):  
Spray Drying ◽  
Encapsulation Efficiency ◽  
Water Solubility ◽  
Hydrophobic Interactions ◽  
Drug Loading ◽  
Weight Ratio ◽  
Sem Analysis ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Dry Powders

In this work, we aimed to improve the encapsulation efficiency of sepiapterin (SP), the natural precursor of the essential cofactor tetrahydrobiopterin (BH4) that displays mild water-solubility and a short biological half-life, within methoxy-poly(ethylene-glycol)-poly(epsilon-caprolactone)(mPEG-PCL) nanoparticles (NPs) by means of its complexation and hydrophobization with 2,3,6-triacetyl-β-cyclodextrin (TAβCD). For this, SP/TAβCD complexes were produced by spray-drying of SP/TAβCD binary solutions in ethanol using the Nano Spray Dryer B-90 HP. Dry powders were characterized by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and transmission and scanning electron microscopy (TEM and SEM, respectively) and compared to the pristine components and their physical mixtures (PMs). Next, SP was encapsulated within mPEG-PCL NPs by nano-precipitation of an SP/TAβCD complex/mPEG-PCL solution. In addition to the nano-encapsulation of a preformed complex within the polymeric NPs, we assessed an alternative encapsulation approach called drying with copolymer (DWC) in which pristine SP, TAβCD, and mPEG-PCL were co-dissolved in a mixture of acetone and methanol at the desired weight ratio, dried under vacuum, re-dissolved, and nano-precipitated in water. The dissolution-drying step was aimed to promote the formation of molecular hydrophobic interactions between SP, TAβCD, and the PCL blocks in the copolymer. SP-loaded mPEG-PCL NPs were characterized by dynamic light scattering (DLS) and SEM. NPs with a size of 74–75 nm and standard deviation (S.D., a measure of the peak width) of 21–22 nm were obtained when an SP:TAβCD (1:1 molar ratio) spray-dried complex was used for the nano-encapsulation and SEM analysis revealed the absence of free SP crystals. The encapsulation efficiency (%EE) and drug loading (%DL) were 85% and 2.6%, respectively, as opposed to the much lower values (14% and 0.6%, respectively) achieved with pristine SP. Moreover, the NPs sustained the SP release with relatively low burst effect of 20%. Overall, our results confirmed that spray-drying of SP/TAβCD solutions at the appropriate molar ratio leads to the hydrophobization of the relatively hydrophilic SP molecule, enabling its encapsulation within mPEG-PCL NPs and paves the way for the use of this strategy in the development of novel drug delivery systems of this vital biological precursor.

Synthesis and Properties of Novel Multiblock Thermoplastic Elastomers - Poly(ester-imide-ether) - Based on Pyromellitic Dianhydride, Glycine, 1,4-Butanediol and Polytetramethylene Glycol

2012 ◽  
Vol 550-553 ◽  
pp. 822-826 ◽  
Author(s):  
Si Chen ◽  
Shao Jian Lin ◽  
Jian Wu Lan ◽  
Jiao Jiao Shang ◽  
Ya Ni Li ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Thermogravimetric Analysis ◽  
1H Nmr Spectroscopy ◽  
Soft Segment ◽  
Thermoplastic Elastomers ◽  
Pyromellitic Dianhydride ◽  
Scanning Calorimetry ◽  
Chemical Structures ◽  
Good Solubility

A series of multiblock thermoplastic ploy(ester imide ether)s elastomers derived from polytetramethylene glycol of molecule weight is 1000 (PTMG1000), 1,4-butanediol (BD), and a new imide diacid monomer were synthesized of Pyromellitic dianhydride (PMDA) and glycine (GLY). was synthesized by two-step melting polycondensation method. Their chemical structures were studied by 1H-NMR spectroscopy as well as their thermal properties of the copolymers were investigated from differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), respectively. Otherwise, the solubility of these polymers was characterized by various organic solvents. The effects of the hard/soft segment content on the thermal properties and soluble behavior were investigated. The result demonstrated that these copolymers had better thermal properties (Tm: 225~280°C and T5% : 350~353°C) than those of conventional thermoplastic elastomers due to the introduction of imide bond. At the same time, the polymers have good solubility.

Influence of Coupling Agent on the Morphology of Multifunctional, Degradable Shape-Memory Polymers

2013 ◽  
Vol 1569 ◽  
pp. 57-64 ◽  
Author(s):  
Liang Fang ◽  
Wan Yan ◽  
Ulrich Nöchel ◽  
Michael Zierke ◽  
Marc Behl ◽  
...  
Keyword(s):  
Coupling Agent ◽  
Hydrolytic Degradation ◽  
Weight Ratio ◽  
Hexamethylene Diisocyanate ◽  
Degree Of Crystallinity ◽  
Shape Effect ◽  
Scanning Calorimetry ◽  
Thermally Induced ◽  
Force Microscopy ◽  
Surface Morphologies

ABSTRACTMultifunctional polymer-based biomaterials, which combine degradability and shapememory capability, are promising candidate materials for biomedical implants. An example is a degradable multiblock copolymer (PDC), composed of poly(p-dioxanone) (PPDO) as hard and poly(ε-caprolactone) (PCL) as switching segments. PDC exhibits a unique linear mass loss during hydrolytic degradation, which can be tailored by the PPDO to PCL weight ratio, as well as an excellent thermally induced dual-shape effect. PDC can be synthesized by co-condensation of two oligomeric macrodiols (PCL-diol and PPDO-diol) using aliphatic diisocyanates as coupling agent. Here, we investigated whether different morphologies could be obtained for PDCs synthesized from identical oligomeric macrodiols (PCL-diol with Mn = 2000 g·mol-1 and PPDO-diol with Mn = 5300-5500 g·mol-1) with 2, 2(4), 4-trimethyl-hexamethylene diisocyanate (TMDI) and 1, 6-hexamethylene diisocyanate (HDI), respectively. More specifically, atomic force microscopy (AFM) was utilized for an investigation of the surface morphologies in solution casted PDC thin films in the temperature range from 20 °C to 60 °C. The results obtained in differential scanning calorimetry (DSC) and AFM demonstrated that different morphologies were obtained when TMDI (PDC-TMDI) or HDI (PDC-HDI) were used as linker. PCL related crystals in PDC-HDI were more heterogeneous and less ordered than those in PDCTMDI, while HDI resulted in a larger degree of crystallinity than TMDI. This research provides some new suggestions for choosing a suitable coupling agent to tailor the required morphologies and properties of SMPs with crystallizable switching segments.

A Solvent-Dependent and Electrochemically Controlled Self-Assembling/Disassembling System

2003 ◽  
Vol 68 (9) ◽  
pp. 1647-1662 ◽  
Author(s):  
Valeria Amendola ◽  
Massimo Boiocchi ◽  
Yuri Diaz Fernandez ◽  
Carlo Mangano ◽  
Piersandro Pallavicini
Keyword(s):  
Equilibrium Mixture ◽  
Bidentate Ligand ◽  
Molecular Structures ◽  
The Self ◽  
Molar Ratio ◽  
Crystal And Molecular Structures ◽  
Self Assembling ◽  
Irreversible Oxidation ◽  
Irreversible Reduction ◽  
Metal Ligand

The bis-bidentate ligand R,S-1,2-diphenyl-N,N'-bis(2-quinolinemethylidene)ethane-1,2-diamine (ligand 4), containing two (iminomethyl)quinoline moieties separated by a cis-1,2-diphenylethylene spacer, forms stable complexes with both CuI and CuII. With CuII, the monomeric 1:1 complex [CuII(4)]2+ is obtained both in CH3CN and CH2Cl2. With CuI and overall 1:1 metal/ligand molar ratio, an equilibrium mixture is obtained in CH3CN, consisting of [CuI(4)2]+, [CuI2(4)2]2+ and [CuI2(4)(CH3CN)4]2+. The preponderant species is the two-metal one-ligand "open" complex [CuI2(4)(CH3CN)4]2+, in which each Cu+ cation is coordinated in a tetrahedral fashion by one (iminomethyl)quinoline unit and by two CH3CN molecules. Precipitation from the equilibrium mixture yields only crystals of [CuI2(4)(CH3CN)4](ClO4)2·2CH3CN, whose crystal and molecular structures have been determined. On the other hand, in the poorly coordinating CH2Cl2 solvent, only the dimeric helical [CuI2(4)2]2+ complex is obtained, when the overall metal/ligand 1:1 molar ratio is chosen. Addition of large quantities of acetonitrile to solutions of [CuI2(4)2]2+ in dichlorometane results in the formation of [CuI2(4)(CH3CN)4]2+, i.e. in the solvent-driven disassembling of the CuI helicate. While electrochemistry in CH3CN is poorly defined due to the presence of more than one CuI species, cyclic voltammetry experiments carried out in CH2Cl2 revealed a well defined behavior, with irreversible oxidation of [CuI2(4)2]2+ and irreversible reduction of [CuII(4)]2+ taking place at separate potentials (∆E ≈ 700 mV). Irreversibility and separation of the redox events are due to the self-assembling and disassembling processes following the reduction and oxidation, respectively.

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