Bio-based Thermoplastic Polyurethane Research Articles

Elektro Çekim Yöntemi ile Haloysit Katkılı Biyo-Bazlı Termoplastik Poliüretan Nanolif Üretimi ve Karakterizasyonu

In this study, it was aimed to produce biocomposite nanofibers by using electrospinning technique and to form biocomposite structure, bio-based thermoplastic polyurethane (BioTPU) and halloysite (HST) mineral obtained from natural sources were used. Electrospinning parameters have been optimized for the production of nanofibers with smooth morphology and the polymer solution with the most suitable parameter was determined. Different concentrations of HST filled BioTPU nanofibers were produced and the rheological behavior of the solutions was investigated with a rotational rheometer before electrospinning to observe the effects of halloysite on fiber morphology. Fourier transform infrared spectroscopy (FTIR) analysis was carried out to determine the chemical composition of acquired nanofibers, and scanning electron microscopy (SEM) was used to monitor surface morphologies. Contact angle measurements were carried out to observe the effects of halloysite on the hydrophilicity of nanofiber. According to rheology results, it has been found out that the solution viscosity, storage modulus (G') and loss modulus (G'') of halloysite increased up to a certain concentration (0.3 % HST), but later caused falls on viscosity. According to the results of FTIR analysis, there is no chemical bond between halloysite and BioTPU, but SEM images show that halloysite was added to the structure of nanofibers. It was also found that the halloysite added to the structure increased the fiber diameters and that the fiber cross-section was not uniformly distributed along the fiber axis. The results of contact angle analysis indicated that acquired nanofibers have hydrophobic surface and the added halloysite decreases contact angles of nanofibers.

Melt processing of nanocomposites of cellulose nanocrystals with biobased thermoplastic polyurethane

AbstractNanocomposites of thermoplastic polyurethane (TPU) with cellulose nanocrystals (CNC) without and with surface treatment are obtained by melt processing. Nanocomposites are obtained with nanofiller weight content near of the theoretical percolation threshold (3.9 wt%). Visual observation of CNC agglomerates is sufficient to prove the inefficiency of the mixing in systems with untreated CNC. The crystallization kinetics of the TPU changes with the addition of CNC and this is confirmed by differential scanning calorimetry analysis. Thermogravimetric analysis prove that the addition of CNC increases the thermal stability of the TPU. From the rheological analysis it is possible to verify the absence of percolation and an intermediate state of sol–gel transition in the nanocomposites. CNC/TPU nanocomposites with 5 wt% of treated CNC present better mechanical performance than de neat TPU and the other processed nanocomposites and display around 130% increase in Young's modulus while retaining significant values of toughness, tensile strength and elongation at break.

Bio-based thermoplastic polyurethane derived from polylactic acid with high-damping performance

The gradual exhaustion of conventional fossil fuels makes it significant to develop renewable materials. Thermoplastic polyurethane (TPU), offering the advantages of processability and recyclability of thermoplastics, is gaining increasing attention for economic and environmental concerns. Despite the broad range of applications, the production of TPU is still highly dependent on fossil-based polyols and isocyanates. The development of sustainable polyols and isocyanates that derived from non-petrochemical sources is highly desirable. Notably, polylactic acid (PLA) is acknowledged as the most promising material in the bio-based polymer sector. In this research, we attempt to use the PLA-derived polyol as a renewable raw material to synthesize PLA-based TPUs. The properties of the PLA-based TPUs are comprehensively characterized by Fourier Transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), and tensile testing. The results showed that the TPUs based on PLA derivative exhibit a balanced mechanical property. Notably, the TPUs exhibit pronounced damping property around room temperature, enabling it as a promising damping material. And its mechanical performances were well maintained while damping performance was markedly enhanced after multiple reprocessing cycles. The value of this work lies in the fact that well-balanced properties of bio-based TPUs have been achieved by the use of renewable poly (lactic acid) derived component, which might be fruitful for increasing the renewable content of TPUs for a sustainable world.

Exploring the role of lignin structure in molecular dynamics of lignin/bio-derived thermoplastic elastomer polyurethane blends

The relaxation behavior of two lignins (Alcell organosolv, OSL, and hydroxypropyl modified Kraft, ML) and bio-based thermoplastic polyurethane (TPU) blends have been studied by Differential scanning calorimetry (DSC), Dynamic-mechanical analysis (DMA) and Dielectric relaxation spectroscopy (DRS). The effect of blending on the glass and local relaxation processes as a function of composition, frequency, and temperature has been assessed. The dielectric spectra were resolved into dipolar relaxations as well as conductive processes for differing blend compositions. Characteristic relaxation times, activation energies and dielectric relaxation strengths of lignin/xTPU blends were also investigated. It was found that blending suppresses the α-relaxation process of the blends compared to virgin TPU. On the other hand, while the position of the β-relaxation was not influenced by blending, a reduction of the activation energies, Ea, of this process was observed in the lignin/xTPU blends. Finally, changes are observed in the conductivity behavior of both blends, with conductivity processes more favorable for the OSL/xTPU blends.

사슬연장제의 종류에 따른 바이오 열가소성 폴리우레탄의 물성변화 연구

Adipic acid와 isosorbide를 사용하여 바이오 폴리에스터 폴리올을 합성하였다. 합성된 바이오 폴리에스터 폴리올을 4,4"-methylene bis(phenyl isocyanate)(MDI), isosorbide, 1,3-propandiol, 1,4-butanediol 3가지 사슬증량제와 1:2.1:1의 비율로 혼합하여 바이오 폴리우레탄을 합성하였다. 바이오 폴리우레탄의 구조를 분석하기 위해서 FTIR, TGA 및 DSC를 사용하였다. 고분자 가공분석기(RPA)의 변형 스윕(strain sweep) 및 온도 스윕(temperature sweep)기능을 사용하여 바이오 폴리우레탄의 점탄성 및 내열성을 조사하였다. UTM, shore A 기기를 사용하여 바이오 폴리우레탄의 인장강도, 경도를 측정하였다. Oven을 사용하여 바이오 폴리우레탄의 내수성을 조사하였다. 바이오 폴리에스터 폴리올, MDI와 isosorbide에 의한 바이오 폴리우레탄이 가장 좋은 기계적 물성과 점탄성을 보여주었다. 1,3-PD에 의한 바이오 폴리우레탄이 더 좋은 내열성을 보여 주었다.

Nanocomposite foams based on flexible biobased thermoplastic polyurethane and ZnO nanoparticles as potential wound dressing materials

In the present study biobased and soft thermoplastic polyurethane (TPU), obtained by polymerization from fatty acids, was used to produce TPU/ZnO nanocomposite foams by thermally induced phase separation method (TIPS). The produced foams were characterized and evaluated regarding their potential uses as wound dressing materials. The structure and morphology of the prepared flexible polymer foams with different content of ZnO nanofiller (1, 2, 5 and 10 wt% related to the polymer) were studied by Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). Highly porous nanocomposite structure made of interconnected pores with dimensions between 10 and 60 μm was created allowing water vapor transmission rate (WVTR) up to 8.9 mg/cm2·h. The TPU/ZnO foams, tested for their ability to support cells and their growth, showed highest cell proliferation for TPU nanocomposite foams with 2 and 5 wt% ZnO. Overall, the nanocomposite foams displayed a low cytotoxic potential (varied proportionally to the ZnO content) and good biocompatibility. All tested nanocomposite foams were found to be significantly active against biofilms formed by different Gram-positive (Enterococcus faecalis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Based on their behaviors, flexible TPU/ZnO nanocomposite foams can be considered for biomedical applications such as potential active wound dressing.

Organophilic graphene nanosheets as a promising nanofiller for bio-based polyurethane nanocomposites: investigation of the thermal, barrier and mechanical properties

The present study focuses on the design of new nanocomposite films using bio-based thermoplastic polyurethane (TPU) as a polymer matrix and long chain amine functionalized reduced graphene oxide (G-ODA) as a nanofiller.

Mechanical, thermo-mechanical and water uptake performance of wood flour filled polyurethane elastomer eco-composites: influence of surface treatment of wood flour

Abstract Alkaline and silane treatments were applied to wood flour (WF) to enrich its adhesion to bio-based thermoplastic polyurethane (TPU) matrix. TPU/WF eco-composites were prepared at a constant ratio of 30% by the melt blending process. The mechanical, thermo-mechanical, melt-flow, water uptake and morphological properties of the materials were investigated. Silane-treated WF filled composite exhibited better mechanical performance with respect to untreated WF due to enhancement of adhesion between WF and TPU matrix after surface treatments. This sample also gave the lowest water absorption value among composites. The results confirmed that silane treatment of WF led to significant improvement on the mechanical and physical properties of TPU-based composites in addition to an improved water resistance for outdoor applications.

Nanocomposites based on renewable thermoplastic polyurethane and chemically modified cellulose nanocrystals with improved mechanical properties

ABSTRACTIn this study, freeze‐dried cellulose nanocrystals (CNC) from eucalyptus, redispersed in dimethylformamide, is grafted with a polyurethane‐based dimer to improve the interaction with the matrix, a biobased thermoplastic polyurethane (TPU). Dimer grafting onto CNC is confirmed by Fourier transform infrared spectroscopy. Wide‐angle X‐rays diffraction and thermogravimetry indicate that neither the CNC crystal structure nor its thermal stability are altered, but its crystalline fraction decreased due to the presence of the dimer on the CNC surface. TPU/CNC nanocomposite films are obtained by solvent casting. Nanocomposites with nanofiller content below the theoretical percolation threshold (3.9 wt %) do not present significant changes in the mechanical properties. However, nanocomposites with 5.0 wt % of treated CNC shown good elongation and a Young modulus increase of 55 and 30% when compared with the neat TPU and untreated nanocomposites of same composition, respectively. In addition to that, the CNC addition increases the film opacity. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46736.

New bio-based thermoplastic polyurethane elastomers from isosorbide and rapeseed oil derivatives

Thermoplastic polyurethanes (TPUs) from fatty acids dimer-based polyester polyols, 4,4′-methylene bis(phenyl isocyanate) (MDI) and isosorbide (ISO) as chain extender were successfully synthesized by a two-stage synthesis. TPUs obtained from isosorbide were compared to the model 1,4-butanediol (BDO) −based materials. Differential scanning calorimetry revealed the phase-separated structure of these materials that displayed a typical thermoplastic elastomer behavior by dynamic mechanical analysis. Samples were further analyzed by transmission electronic microscopy, atomic force microscopy and compression set; hardness and water uptake were also monitored. Isosorbide was found to slightly increase the glass transition and melting temperatures of MDI-based hard segments, and to slightly decrease the stability and quality of phase segregation. This resulted in an increase in rubber modulus and hardness, shape retention, in a slight increase in the temperature of the α relaxation of the soft segment domains and in a characteristic microphase morphology. Moreover the use of the rather hydrophobic fatty acid-based soft segment allowed to keep the water uptake at a rather low level, in spite of the presence of isosorbide in the formulation.

Rennovia enters piloting stage of bio-based 1,6-HDO process

The application of thermoplastic polyurethanes (TPU) is becoming more and more extensive, and the decreasing of used petrochemical monomers and reduction of energy for the polymerization and processing processes is getting increasingly important. In this paper, we confirmed the positive influence of high bio-based monomers contents (by replacing petrochemical polyol and glycol by bio-based counterparts) on processing and properties of obtained materials. A series of partially bio-based thermoplastic poly(ether-urethane)s (bio-based TPU) were obtained from bio- and petrochemical-based polyols, bio-based 1,4-butanediol, and 4,4′-diphenylmethane diisocyanate by the two-step method without using any solvents. Both the monomers’ origin and polyurethane prepolymer processing parameters were taken into account in characterization of the obtained materials. The TPUs' chemical structure was analyzed by FTIR spectroscopy and 1H NMR and the number average molecular weight was examined by 1H NMR and GPC. The measurements of dynamic mechanical thermal analysis, tensile test, hardness, density method, and rheological behavior provided useful information about the properties of prepolymers and TPUs. The processing properties and an activation energy of prepared materials was examined using the melt-flow index. It has been confirmed that despite the origin of polyols obtained thermoplastic poly(ether-urethanes) exhibited comparably good mechanical and thermo-mechanical properties, and an appropriate melt flow index facilitates their processing. Nevertheless, the use of high amount of bio-based monomers resulted in obtaining more eco-friendly materials.

Synthesis and characterization of advanced biobased thermoplastic nonisocyanate polyurethanes, with controlled aromatic-aliphatic architectures

The aim of this study was the elaboration of thermoplastic and biobased nonisocyanate polyurethanes (TNIPUs) based on different aromatic-aliphatic architectures. A rigid aromatic bis(cyclic carbonate) was synthesized from terephthalic acid, and subsequently used with various diamines for the preparation of TNIPUs. A two-step method was investigated to design advanced macromolecular architectures. All TNIPUs and corresponding intermediates were fully characterized. The influence of various parameters such as the ratio between the constituting building blocks and the chemical structure on NIPU properties was studied. Thermal and mechanical results show that the TNIPUs presenting the highest molar masses and the highest properties were synthesized from dimer diamine prepolymers. A high content of terephthalic acid and short-chain diamine increases the glass transition temperature and leads to good performances, with a balance between elongation and tensile strength properties. The final TNIPUs present biobased content up to 76%.

Influence of Surface Modifications of Flax Fiber on Mechanical and Flow Properties of Thermoplastic Polyurethane Based Eco-Composites

ABSTRACTIn this study, several treatments including alkali, permanganate, peroxide and silanization were applied to flax fiber (FF) to improve its adhesion to bio-based thermoplastic polyurethane (TPU) matrix. TPU/FF composites were prepared at a constant ratio of 30 wt% by using extrusion process. Their mechanical properties, modulus of elasticity, water uptake behaviors, melt-flow properties and morphologies of composites were investigated. All treatments resulted in better mechanical properties with respect to untreated FF. Silane treated FF containing composite exhibited the highest tensile strength and lowest water absorption. Results confirmed that surface modifications improve the adhesion between FF and TPU matrix.

Synthesis of bio-based thermoplastic polyurethane elastomers containing isosorbide and polycarbonate diol and their biocompatible properties.

A new family of highly elastic polyurethanes (PUs) partially based on renewable isosorbide were prepared by reacting hexamethylene diisocyanate with a various ratios of isosorbide and polycarbonate diol 2000 (PCD) via a one-step bulk condensation polymerization without catalyst. The influence of the isorsorbide/PCD ratio on the properties of the PU was evaluated. The successful synthesis of the PUs was confirmed by Fourier transform-infrared spectroscopy and (1)H nuclear magnetic resonance. The resulting PUs showed high number-average molecular weights ranging from 56,320 to 126,000 g mol(-1) and tunable Tg values from -34 to -38℃. The thermal properties were determined by differential scanning calorimetry and thermogravimetric analysis. The PU films were flexible with breaking strains from 955% to 1795% at from 13.5 to 54.2 MPa tensile stress. All the PUs had 0.9-2.8% weight lost over 4 weeks and continual slow weight loss of 1.1-3.6% was observed within 8 weeks. Although the cells showed a slight lower rate of proliferation than that of the tissue culture polystyrene as a control, the PU films were considered to be cytocompatible and nontoxic. These thermoplastic PUs were soft, flexible and biocompatible polymers, which open up a range of opportunities for soft tissue augmentation and regeneration.

Elaboration and properties of novel biobased nanocomposites with halloysite nanotubes and thermoplastic polyurethane from dimerized fatty acids

Nanocomposites of biobased thermoplastic polyurethane (TPU) from dimer fatty acids and halloysite nanotubes (HNT) were elaborated by different melt processing routes such as direct mixing (1 step process) and masterbatch/dilution (2 steps process), at different temperatures (150 and 180 °C). Rheological and transmission electron microscopy (TEM) analyses indicated that the HNT distribution and dispersion were dependent on the processing conditions: the 2 steps process produced well dispersed nanocomposites and the masterbatch dilution at 180 °C improved the HNT distribution through the TPU. Consequently, a high reinforcement was achieved, with a 40% increase in the elastic modulus and 8 °C increase in the relaxation temperature related to the glass transition of the TPU soft segments. Furthermore, a percolated network was attained, even if a large extent of HNT breaking was observed during processing, suggesting that a synergistic effect between the HNT particles and the TPU's hard segments in the molten state occurred. Thus, HNT nanotubes can be seen as highly reinforcing nanofillers when good dispersion and distribution are achieved through the polymeric matrix.

Development of bio-based thermoplastic polyurethanes formulations using corn-derived chain extender for reactive rotational molding

Partly bio-based segmented thermoplastic polyurethane (TPU) formulations were developed to fulfill the requirements of the reactive rotational molding process. They were obtained by one-shot bulk polymerization between an aliphatic diisocyanate (1,6-hexamethylene diisocyanate), a polyether polyol as macrodiol (polyethylene glycol) and a bio- based corn-derived 1,3-propanediol as chain extender (CE), in presence of a catalyst, at an initial temperature of 45°C. Equivalent TPU formulations with classical petroleum-based 1,3-propanediol were also prepared for a purpose of compar- ison. TPU with different soft to hard segment (SS/HS) ratios were synthesized by varying the macrodiol and CE concentra- tions in the formulations. For each formulation, the evolution of the reaction temperature as a function of time was monitored and the kinetics of polymerization was studied by Fourier Transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR). The morphology, thermal properties, solubility in different solvents and tensile properties of the final products were analyzed. All synthesized polyurethanes are 100% linear polymers and the extent of microphase separation, as well as the thermal and mechanical properties highly depends on the HS content, and glass transition temper- ature and Young modulus can be tuned by adjustment of the SS/HS ratio. All results indicate that petrochemical CE can be replaced by its recently available corn-derived homologue, without sacrificing any use properties of the final polyurethanes.

Development of Water Blown Bio-Based Thermoplastic Polyurethane Foams

Water blown biobased thermoplastic polyurethane (TPU) foams were prepared using synthetic and biobased chain extender. The concentration of chain extender, blowing agent (BA) and surfactant were varied and their effects on physical, mechanical and morphological properties of foams were investigated. Density, compressive strength and modulus of foams decreases with an increase in BA content and increased with chain extender concentration, but do not change significantly with change in surfactant concentration. The glass-transition temperatures of the foam samples increases with an increase in BA and chain extender concentration. The cell size of the foam sample increases slightly with an increase in BA whereas chain extender concentration has no effect on cell size.

Relationship between morphology, properties and degradation parameters of novative biobased thermoplastic polyurethanes obtained from dimer fatty acids

Biobased thermoplastic polyurethanes (TPUs) obtained from dimer acid-based polyols, 4,4′-diphenylmethane diisocyanate and 1,4-butanediol were synthesised by using a two-step prepolymer process. The effect of dimer acid-based polyols on the processing parameters was investigated. A full thermal, mechanical and thermo-mechanical characterisation of TPUs synthesised with different hard segment (HS) contents was also carried out. Thermogravimetric analysis showed the presence of three degradation steps which varied between the different TPU structures depending on the HS content. Colour tests showed substantial differences between TPU samples which were related to degradation parameters. Initial degradation temperatures were lower than the polyol's one and decreased with increasing HS contents. Tensile tests showed high deformation at break for these elastomeric TPU samples, except for the sample with 40 wt% of HS. Finally, rheology studies revealed that the melting temperature generally decreased with higher HS contents.

Enhancement of thermal stability, strength and extensibility of lipid-based polyurethanes with cellulose-based nanofibers

Cellulose was extracted from lignocellulosic fibers and nanocrystalline cellulose (NC) prepared by alkali treatment of the fiber, steam explosion of the mercerized fiber, bleaching of the steam exploded fiber and finally acid treatment by 5% oxalic acid followed again by steam explosion. The average length and diameter of the NC were between 200-250 nm and 4–5 nm, respectively, in a monodisperse distribution. Different concentrations of the NC (0.1, 0.5, 1.0, 1.5, 2.0 and 2.5% by weight) were dispersed non-covalently into a completely bio-based thermoplastic polyurethane (TPU) derived entirely from oleic acid. The physical properties of the TPU nanocomposites were assessed by Fourier Transform Infra-Red spectroscopy (FTIR), Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), Dynamic Mechanical Analysis (DMA) and Mechanical Properties Analysis. The nanocomposites demonstrated enhanced stress and elongation at break and improved thermal stability compared to the neat TPU. The best results were obtained with 0.5% of NC in the TPU. The elongation at break of this sample was improved from 178% to 269% and its stress at break from 29.3 to 40.5 MPa. In this and all other samples the glass transition temperature, melting temperature and crystallization behavior were essentially unaffected. This finding suggests a potential method of increasing the strength and the elongation at break of typically brittle and weak lipid-based TPUs without alteration of the other physico-chemical properties of the polymer.

Synthesis and properties of bio‐based thermoplastic polyurethane based on poly (L‐lactic acid) copolymer polydiol

AbstractThe goal of this work is the synthesis of a new kind of bio‐based thermoplastic polyurethane (BTPU) based on poly(L‐lactic acid) (PLA) and poly(tetramethylene) glycol (PTMEG) segments via chain‐extension reaction of dihydroxyl terminated (HO‐PLA‐PTMEG‐PLA‐OH) copolymer using hexamethylene diisocyanate (HDI) as a chain extender. Polydiols were synthesized through polycondensation of lactic acid and PTMEG in bulk. The chemical structures and molecular weights of polydiols and BTPUs containing different segment lengths and weight fractions of PLA, were characterized by 1H‐NMR and FTIR. The effects of the structures on the physical properties of BTPUs were studied by means of DSC, SEM, and tensile test; crystallization behavior was characterized by POM. The DSC and SEM results indicate that PLA segment is perfectly compatible with PTMEG segment and the crystallization of BTPU is predominantly caused by PLA segment. Polydiol with lower PLA content shows lower Tg and lower crystallinity. Tensile test shows that the elongation at break of BTPU is above 340% at the composition of PLA/PTMEG = 80/20 (w/w). © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012