Influence of soft segment molecular weight on the mechanical hysteresis and set behavior of silicone-urea copolymers with low hard segment contents

Jonáš, Alexandr; Eynur, Tugba; Bilgin, Sevilay; Wilkes, Garth L.

doi:10.1016/j.polymer.2010.11.040

Cited by 75 publications

(61 citation statements)

References 22 publications

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“…5,19 It is also higher than the crystallinity (~32%) reported for CNC obtained after prolonged dry milling (1-6 days) and dilute acid hydrolysis. 42 Nevertheless, the maximum milling time was only 60 minutes via the wet milling conditions used in this study lead to less destruction of the crystal structure than seen with extensive dry milling. …”

Section: Crystallinity Of Cncmentioning

confidence: 75%

“…Cellulose can be found in the cell walls of plants, particularly in the stalks, stems, trunks and all woody portions. 42 In 1838, cellulose was first discovered and extracted by Anselme Payen. 43 Since then, extensive studies of its physical and chemical properties have been undertaken.…”

Section: Cellulose Nanocrystals -A Sustainable Nanomaterialsmentioning

confidence: 99%

“…41 For thermoplastic polyurethane, this is an important property to be determined as it is usually affected by the hard segments content. 42 In this work 2 MPa of stress have been applied for 6 hours to observe the deformation of TPU control and nanocomposites. In Figure 7.13 shows the tensile-creep curves where an initial tensile strain obtained was slightly varied immediately after 2MPa of stress was applied.…”

Section: Creep Behaviourmentioning

confidence: 99%

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Cellulose nanocrystals reinforced thermoplastic polyurethane nanocomposites

Amin¹,

Najwa²

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Thermoplastic polyurethane (TPU) is one of the most widely used thermoplastic elastomers (TPE) due to its high strength and tear resistance, good elasticity, flexibility and damping properties.Enhancement of TPU properties can be achieved by either varying the hard-soft segment composition ratio or by the reinforcement with micro or nanoscale fillers. In the last decade, cellulose nanocrystals (CNC) have gained an increasing degree of interest from both academics and industries as 'sustainable nanomaterials', as they have high-axial mechanical properties and reinforcing capability, abundance, low density, renewability and biodegradability. Contemporary research activities centred on the reinforcement of TPU with CNC have typically employed solventbased fabrication methods (solution/wet casting). For the successful translation of this new class of nanocomposite materials from laboratory research to widespread applications, processing via scalable approaches has to be demonstrated. The utility of CNC as TPU reinforcers has also been limited by the poor thermal stability of CNC, which are typically isolated via acid hydrolysis, as well as the poor quality of dispersion achieved when more scalable methodologies are used (eg. melt compounding). Thus, this study firstly aims to explore, optimise and develop CNC with enhanced thermal stability, and secondly, to incorporate these more thermostable CNC into high performance TPU nanocomposites via scalable melt-compounding and reactive extrusion methods.The research thesis is presented in three main parts. The first part is focused on the production/isolation of CNC with enhanced thermal stability and at a high production yield. CNC has been isolated via two methods, acid hydrolysis using mild acid and a scalable high energy bead milling process. Both processes have been optimised to isolate CNC with requisite thermal stability and dispersibility for TPU host polymers. The second part is focused on the processability of CNC into the TPU matrix via an intermediate-scale traditional twin screw extrusion melt compounding method. The third and final part is focused on the processing TPU/CNC nanocomposites via a large-scale reactive extrusion method, by pre-dispersing CNC in polyol and then performing in-situ polymerisation in a twin-screw extruder (i.e. reactive extrusion). The main outcomes or observations from this study are:• Isolation of CNC with enhanced thermal stability and dispersibility via mild acid hydrolysis, and with a higher production yield than the previously reported methods• Acid-free isolation of CNC with enhanced thermal stability at high production yields• Organic solvent-free processing of TPU/CNC nanocomposites • The performance of the host TPU matrix, a "workhorse" aromatic polyether grade, is remarkably enhanced by the incorporation strategies reported, without negatively affecting the important elastic properties and compliance of the TPU iii

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Section: Crystallinity Of Cncmentioning

confidence: 75%

Section: Cellulose Nanocrystals -A Sustainable Nanomaterialsmentioning

confidence: 99%

Section: Creep Behaviourmentioning

confidence: 99%

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Cellulose nanocrystals reinforced thermoplastic polyurethane nanocomposites

Amin¹,

Najwa²

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“…In this also industrially used approach, polar hydrogen bonding urea structures are formed during the polymerization reaction . As already mentioned, urea segments and PDMS segments tend to undergo phase separation, which gives rise to typical properties of a TPE …”

Section: Introductionmentioning

confidence: 87%

PDMS‐Containing Alternating Copolymers Obtained by Click Polymerization

Bretzler

Grübel

Meister

et al. 2014

Macro Chemistry & Physics

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The copper(I)‐catalyzed alkine–azide cycloaddition (CuAAC) click polymerization is used for the synthesis of novel poly(dimethylsiloxane) (PDMS)‐containing alternating copolymers in a straightforward AA/BB polyaddition approach. The versatility of the CuAAC reaction allows incorporation of a series of different monomers varying in geometry, size, and functionality. A structure–property relation is revealed that shows that the polymer properties are dependent not only on the type of functionality incorporated but also on the size and geometry of the comonomer. The spectrum of properties that can be covered is highly interesting, ranging from viscous oils to brittle solids. Targeted application of monomers even gives access to properties that are typical for thermoplastic elastomers. Additional studies concerning the acceleration of the polymerization reaction support mechanistic considerations about a binuclear active species.

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“…The synthesis of hybrid materials combining the properties of both polymers seems to be justified, which is additionally reflected by the latest research reports [4][5][6][7][8][9][10][11][12] confirming that polyurethanes modified with siloxanes are characterized with lower glass transition temperature and enhanced thermal stability with simultaneously increased hydrophobicity. Because of this they have been used as protective coatings, selective membranes, medical implants and surface modifiers for various polymers and fibers [7,8,13].…”

Section: Introductionmentioning

confidence: 90%

Thermal and surface properties of hybrid materials obtained from epoxy-functional urethane and siloxane

2015

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In this work, a series of high-solids crosslinked hybrid networks based on the epoxy-terminated urethane oligomer and the comb-like structure epoxyfunctional siloxane cured with diethylenetriamine, were obtained. The structure of the obtained poly(urethane-siloxane) thermosets was confirmed by FTIR spectroscopy. The samples were submitted to detailed thermal degradation investigations at non-isothermal conditions in nitrogen and air. The contact angles of the coatings and free surface energy calculated by Owens-Wend as well as van OssGood method, were studied. Some coating properties of the obtained hybrid materials were also investigated. The synthesized poly(urethane-siloxane) networks are hydrophobic materials, with free surface energy of 26-29 mJ/m 2 . The thermal stability and hardness of these increases with increasing siloxane content.

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Influence of soft segment molecular weight on the mechanical hysteresis and set behavior of silicone-urea copolymers with low hard segment contents

Cited by 75 publications

References 22 publications

Cellulose nanocrystals reinforced thermoplastic polyurethane nanocomposites

Cellulose nanocrystals reinforced thermoplastic polyurethane nanocomposites

PDMS‐Containing Alternating Copolymers Obtained by Click Polymerization

Thermal and surface properties of hybrid materials obtained from epoxy-functional urethane and siloxane

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