Comparison of properties of thermoplastic polyurethane elastomers with two different soft segments

Two series of thermoplastic polyurethane elastomers [poly(propylene glycol) (PPG) based PP samples and poly(oxytetramethylene)glycol (PTMG) based PT samples] were synthesized from isophorone diisocyanate (IPDI)/1,4-butanediol (BD)/PPG and IPDI/BD/PTMG. The IPDI/BD based hard segments contents of polyurethane prepared in this study were 40–73 wt %. These polyurethane elastomers had a constant soft segment molecular weight (average M_n, 2000) but a variable hard segment block length (n, 3.5–17.5; average M_n, 1318–5544). Studies were made on the effects of the hard segment content on the dynamic mechanical thermal properties and elastic behaviors of polyurethane elastomers. These properties of PPG based PP and PTMG based PT samples were compared. As the hard segment contents of PP and PT samples increased, dynamic tensile modulus and α-type glass transition temperature (T_g) increased; however, the β-type T_g decreased. The permanent set (%) increased with increasing hard segment content and successive maximum elongation. The permanent set of the PT sample was lower than that of the PP sample at the same hard segment content. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1349–1355, 1998     

Structure and properties of thermoplastic poly(glycerol sebacate) elastomers originating from prepolymers with different molecular weights

Thermoplastic poly(glycerol sebacate) (TMPGS) elastomers originating from three prepolymers with different molecular weights were prepared first, and then the structure and properties were studied. Specifically, by swelling tests, gel permeation chromatography, X‐ray diffraction, and differential scanning calorimetry, the crosslinking densities, sol contents and compositions, crystallization, and thermal performances of three TMPGSs were examined. Finally, the degradability in a 37°C phosphate‐buffered saline solution (pH = 7.4) was also illuminated. The three TMPGSs had similar chemical structures, but the different molecular weights of the prepolymers influenced their final compositions and properties to a great extent. Furthermore, both hydrogen bonding and plasticization action in the elastomers played important roles in balancing the overall properties of the TMPGS elastomers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1131–1137, 2007     

Dynamically vulcanized nitrile rubber/polypropylene thermoplastic elastomers

A new compatibilized method was used to prepare thermoplastic elastomer (TPE) of nitrile rubber (NBR) and polypropylene (PP) with excellent mechanical properties by dynamic vulcanization. Glycidyl methacrylate (GMA) grafted PP/amino‐compound was used as a compatibilizer. The effects of the curing systems, compatibilizer, PP type, and reprocessing on the mechanical properties of NBR/PP thermoplastic elastomers were investigated in detail. Experimental results showed that the addition of amino‐compound in the compatibilzer can significantly increase the mechanical properties of the NBR/PP thermoplastic elastomer. Compared with other amino‐compounds, diethylenetriamine (DETA) has the best effect. PP with higher molecular weight is more suitable for preparing NBR/PP thermoplastic elastomer with high tensile strength and high elongation at break. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2862–2866, 2002     

Compositional trend analysis on poly(phenylene ether) based thermoplastic elastomers

Detailed statistical trend analysis of thermoplastic elastomers based on poly (phenylene ether) (PPE), polystyrene (PS), ethylene vinyl acetate (EVA) and styrene‐ethylene‐butylene‐styrene (SEBS) was done through Design Expert software by Stat‐Ease. D optimal crossed design was followed to capture the interaction with the parameters. Effect of blend ratio, vinyl acetate (VA) content of EVA, molecular weight (MW) of SEBS and intrinsic viscosity (IV) of PPE on the blend performance (response) was studied in detail. Design of Experiment (DOE) analysis showed the “optimized formulation” of the blend. Increase in PPE‐polystyrene (PS) content increased tensile strength and modulus of the blend, followed by a decrease in strain at break. However, EVA had a reverse effect on tensile strength and modulus. Strain at break increased significantly with increasing SEBS content in the blend. Graphical and numerical optimization showed that superior mechanical properties (tensile strength, strain at break and modulus) could be achieved at VA content ～ 50% at a particular loading of EVA. Low MW SEBS was found to be more compatible with the other components of the blend. Mechanical properties of the quaternary blend were marginally affected with change in IV of PPE in the range of 0.33 to 0.46. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of co‐hard segments on the microstructure and properties thermoplastic poly(ether ester) elastomers

A thermoplastic poly(ether ester) elastomer (TPEE) is composed of polyester hard segments and polyether soft segments. Polyester and polyether segments are often homopolymer segments. This work aims at incorporating poly(butylene phthalate (PBP) as co‐hard segments in the hard segments of poly(butylene terephthalate) (PBT)‐b‐poly(tetramethylene oxide) (PTMO) thermoplastic elastomer, and investigating structures and properties of the resulting materials, denoted as (PBT‐co‐PBP)‐b‐PTMO. (PBT‐co‐PBP)‐b‐PTMO was synthesized from dimethyl terephthalate (DMT), dimethyl phthalate (DMP), PTMO (M_n = 1000 g/mol), and 1,4‐butanediol (BDO). The crystallinity of (PBT‐co‐PBP)‐b‐PTMO first decreased and then increased with increasing PBP content from 5% to 10% due to a decrease in the average sequence length of the PBT hard segments. Its elongation at break was increased by 200–350%. When the mass fractions of PBT and PBP were 42% and 8%, respectively, the (PBT‐co‐PBP)‐b‐PTMO showed the best performance in terms of permanent deformation, strength, and hardness whose values were 30%, 25 MPa, and 37 D, respectively. All the synthesized copolymers had good thermal stability with a decomposition temperature of 400°C or so. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43337.     

Stress-strain curves for polyurethane elastomers: A statistical assessment of constitutive models

Polyurethane elastomers (PUEs) are broadening applications attributed to their highly tunable mechanical properties, and the stress–strain curve is one of the most important characters. Theoretically, dozens of constitutive models have been developed to interpret the stress–strain curve for rubber-like materials but their applicability on PUEs is still suspicious, which results in the selection of models and the initialization of model parameters need expertise experience. We performed a statistical assessment of 25 constitutive models (10 physical and 15 phenomenological) based on a comprehensive dataset with 529 stress–strain curves for PUEs. The average coefficients of determination for the whole curve can be improved from 0.676 for the phantom model (1 parameter) to 0.990 for the Bechir model (6 parameters), and the percentage of well-fitted curves increases from 6% to 92%. Constitutive models with both the first- and the second-invariant, in logarithmic or exponential expression for strain perform better.     

Synthesis and material properties of elastomeric high molecular weight polycycloacetals derived from diglycerol and meso-erythritol

Copolymerizing glutaraldehyde with tetraols such as diglycerol, meso-erythritol, and pentaerythritol is particularly effective for forming very high molecular weight polycycloacetals (M_n up to 65,000 g/mol) with elastomeric properties and up to 70% biorenewable content by weight. Altering the tetraol monomer feed ratio provides control over the polycycloacetal's tensile properties. The polymerizations are high-yielding, readily scalable, and employ commercially available starting materials that are used without further purification. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48780.     

Waste ground rubber tire powder/thermoplastic vulcanizate blends: Preparation,characterization, and compatibility

In this article, waste ground rubber tire (WGRT) powder was introduced into thermoplastic vulcanizate (TPV) to prepare the blends of WGRT powder/TPV. The mechanical, rheological, thermal aging, and dynamic properties of the blends were investigated with respect to the particle size and dosage of WGRT powder. The results showed that tensile strength, tear strength, elongation at break, and tensile permanent deformation of the blends increased with the decrease in WGRT particle size and decreased with the dosage of WGRT. The effects of different types and dosages of compatibilizers on mechanical and rheological properties of the blends were studied. The results showed that the compatibilizer PP‐g‐MAH could effectively improve the interfacial compatibility between WGRT and the TPV matrix to enhance the comprehensive properties of blends. The TPV/WGRT/PP‐g‐MAH blends obtained the best overall properties when prepared at the weight ratio 100/30/5. Rheological studies demonstrated that the WGRT/TPV blends represented lower apparent viscosity after PP‐g‐MAH were added, which means that processing performance of the blends was improved by PP‐g‐MAH. Scanning electron microscopy was used to study the morphologies of the blends. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39868.     

Morphology and mechanical properties of ethylene‐vinyl acetate rubber/polyamide thermoplastic elastomers

High performance thermoplastic elastomers based on ethylene‐vinyl acetate rubber (EVM) and ternary polyamide copolymer (tPA) were prepared through a dynamic vulcanization process in the presence of dicumyl peroxide (DCP). The morphology, crystallization, and mechanical properties of the EVM/tPA blends were studied. A phase transition of EVM/tPA blend was observed at a weight ratio of 60/40. The presence of EVM increased the melting enthalpy at the high temperature of tPA, ascribing to the heterogeneous nucleating effect of EVM. The tensile strength of EVM/tPA (70/30) blends was increased up to 20.5 MPa as the DCP concentration increased to 3.5 phr, whereas the elongation at break of the blends kept decreasing as the DCP concentration increased. The addition of ethylene‐acrylic acid copolymer (EAA) or maleic anhydride‐grafted EVM (EVM‐g‐MAH) to the EVM/tPA blends both induced finer dispersion of the EVM particles in the tPA phase and improvement in the tensile strength and elongation at break of the blends, which were ascribed to the compatibilization of EAA or EVM‐g‐MAH. Finally, a high performance EVM/tPA (70/30) thermoplastic elastomer with Shore A hardness of 75, tensile strength of 24 MPa, elongation at break of 361%, and set at break of 20% was obtained by adding 5 wt % of EVM‐g‐MAH and 3.5 phr DCP. It has great potential in automotive and oil pipeline applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Property reinforcement of silicone dielectric elastomers filled with self‐prepared calcium copper titanate particles

In this article, submicron and micron calcium copper titanate (CCTO) crystallites with different morphologies were successfully designed and prepared by directly thermal treatment method and molten salt method, respectively. Then, the silicone elastomer filled with self‐prepared CCTO particles had high dieletric constant, low dielectric loss, and actuated strain which was greatly improved at low electric field. The dieletric constant at 50 Hz obviously increased from 2.15 for pure silicone elastomer to 4.37 and 4.18 for the submicron and micron CCTO/poly (dimethyl siloxane) (PDMS) composites. The dielectric loss of the composites retained at a low value (less than 0.06). Meanwhile, the elastic modulus of CCTO/PDMS composites was increased slightly only with a good flexibility. Compared to pure silicone elastomer (2.25%), the submicron and micron CCTO/PDMS composites with 2 wt % content exhibited a greater strain of 7.69% and 9.83% at a low electric field of 5 V/μm. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42613.     

Effect of the compatibilizer,on the engineering properties of TPV based on Hypalon® and PP prepared by dynamic vulcanization

Elastomeric Chlorosulfonated polyethylene (Hypalon^®) and thermoplastic Polypropylene (PP) based thermoplastic vulcanizates (TPVs) were prepared in presence of different doses of compatibilizer, maleic anhydride grafted PP (PP‐g‐MA) by employing dynamic vulcanization technique. The effect of incorporation in different proportions of compatibilizer on mechanical, spectral, morphological, thermal, and rheological properties of such TPVs was studied and the same were compared to that of virgin PP and amongst themselves. The mechanical analysis of the prepared TPVs exhibited significant improvements in stress at 25% modulus, ultimate tensile strength (UTS), and hardness values. FTIR studies revealed that a chemical interaction had taken place between Hypalon^® and functionalized compatibilizer during the process of dynamic vulcanization which led to an enhancement of interfacial adhesion between them. The two‐phase morphologies were clearly observed by scanning electron microscopic studies. The T_g values of Hypalon^® was modified in the TPVs as exhibited by differential scanning calorimetric studies. TGA studies indicated the increase in thermal stability of all TPVs with respect to the elastomeric Hypalon^®. Rheological properties showed that the compatibilizer reduces the melt viscosity of TPVs and thus facilitates the processibility of such TPVs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40312.     

Mechanical and thermal properties of polyurethane elastomers based on hydroxyl‐terminated polybutadienes and biopitch

Biopitch is a renewable source of polyol obtained from Eucalyptus tar distillation, which was studied as an active component of polyurethane (PU). The polymerization occurred in one step, with a mixture of biopitch and hydroxyl‐terminated polybutadiene polyols reacted with 4‐4′‐diphenyl methane diisocyanate in the presence of dibutyltin dilaurate. Solid‐state ¹³C‐NMR, IR spectroscopy, elemental analysis, and thermal analysis [thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)] were used to characterize the biopitch. The biopitch sample showed an aromatic and oxygenated structure with great thermal stability at high temperatures. Multiphasic PUs were synthesized and characterized by IR spectroscopy (attenuated total reflectance), elemental analysis, thermal analysis (TGA and DSC), mechanical assays (tensile strength, elongation at break, toughness, hardness, and resilience), and water absorption resistance (ASTM D 570‐81). In a comparative study of the synthesized elastomers, biopitch content increased tensile strength and hardness and decreased thermal stability, elongation at break, and water absorption. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 759–766, 2003     

The preparation and thermomechanical properties of high-temperature foams based on thermoplastic poly(phthalazinone ether ketone)

Poly(phthalazinone ether ketone) (PPEK) is an amorphous thermoplastic polymer with a high glass transition temperature (T_g) exceeding 250°C. We describe the preparation of foams from PPEK and characterize their properties. PPEK foams were prepared using dichloromethane as a foaming agent. The foaming agent was swollen into discs of the PPEK, which were then foamed by heating. Foams could be prepared at temperatures far below the T_g of the PPEK due to plasticization of the polymer by the foaming agent. Foams with densities ranging from 0.1 to 0.65 g/cm³ were prepared. Their thermal conductivity and modulus (measured approximately by indentation tests) were found to decrease with density, and the trends were similar to those expected from existing models. The foams could be annealed at 200°C without collapse suggesting that they may be useful in structural or insulation applications where stability at high temperature is essential.     

Efficiency of silver‐based antibacterial additives and its influence in thermoplastic elastomers

Styrene‐butylene/ethylene‐styrene‐based thermoplastic elastomers (TPE) are polymers with soft touch properties that are widely used for manufacturing devices that involve hand contact. However, when contaminated with microorganisms these products can contribute to spreading diseases. The incorporation of antibacterial additives can help maintain low bacteria counts. This work evaluated the antibacterial action of TPE loaded with silver ions and silver nanoparticles. The additives nanosilver on fumed silica (NpAg_silica), silver phosphate glass (Ag⁺_phosphate), and bentonite organomodified with silver (Ag⁺_bentonite) were added to the TPE formulation. The compounds were evaluated for tensile and thermal properties and antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). All the additives eliminated over 90% of E. coli, but only NpAg_silica killed more than 80% of S. aureus population. The better effect of NpAg_silica was attributed to the additive's high specific surface area, which promoted greater contact with bacteria cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43956.     

Preparation and properties of segmented thermoplastic polyurethane elastomers with two different soft segments

Thermoplastic polyurethane elastomers were prepared from 4,4‐diphenylmethane diisocyanate (MDI)/1,4‐butanediol (BD)/poly(propylene glycol) (PPG) and MDI/BD/poly(oxytetramethylene glycol) (PTMG). The MDI/BD‐based hard‐segment content of polyurethane prepared in this study was of 39–65 wt %. These polyurethane elastomers had a constant soft‐segment molecular weight (M_n , 2000), but a variable hard‐segment block length (n, 3.0–10.1; M_n , 1020–3434). The effects of the hard‐segment content on the thermal properties and elastic behavior were investigated. These properties of the PPG‐based MPP samples and the PTMG‐based MPT samples were compared. The polyurethane prepared in this study had a hard‐segment crystalline melting temperature in the range of 185.5–236.5°C. With increasing hard‐segment content, the dynamic storage modulus and glass transition temperature increased in both the MPP and MPT samples. The permanent set (%) increased with increasing hard‐segment content and successive maximum elongation. The permanent set (%) of the MPP samples was higher than that of MPT samples at the same hard‐segment content. The value of K (area of the hydrogen‐bonded carbonyl group/area of the free carbonyl group) increased with increasing hard‐segment content in both the MPP and MPT samples, and the K value of the MPT samples was higher than that of the MPP samples at the same hard‐segment content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 345–352, 1999     

Mechanical properties of thermoplastic elastomers based on silicone rubber and an ethylene–octene copolymer by dynamic vulcanization

Thermoplastic vulcanizates (TPVs) are a special class of thermoplastic elastomers that are generally produced by the simultaneous mixing and crosslinking of a rubber with a thermoplastic polymer at an elevated temperature. Novel peroxide‐cured TPVs based on blends of silicone rubber and the thermoplastic Engage (an ethylene–octene copolymer) have been developed. These TPVs exhibit very good overall mechanical and electrical properties. With an increasing concentration of dicumyl peroxide, the tensile strength, modulus, and hardness of the TPVs increase, whereas the elongation at break decreases. Significant correlations have been obtained from oscillating disc rheometer torque values with various physical properties, such as the modulus and tension set of the TPVs. The aging characteristics and recyclability of the silicone‐based TPVs are also excellent. Scanning electron microscopy photomicrographs of the TPVs have confirmed a dispersed phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

PAMMO基热塑性弹性体的合成及表征

以聚3–叠氮甲基–3–甲基氧杂环丁烷(PAMMO)为软段,2,4–甲苯二异氰酸酯和1,4–丁二醇为硬段,1,2–二氯乙烷为溶剂,采用溶液聚合一步法合成了含叠氮基热塑性弹性体(ATPE)。通过IR、GPC、DSC、力学性能测试等手段对ATPE的结构和性能进行了表征。结果表明:所合成的ATPE具有典型的叠氮聚醚聚氨酯特征;当R值为0.98,硬段质量分数为40%~45%时,聚合物的力学性能较优;ATPE的数均相对分子质量为50 000左右,玻璃化转变温度为–21.26℃,分解峰温为260.2℃。     

Influence of thermoplastic elastomers on adhesion in polyethylene–wood flour composites

The mechanical properties of recycled low-density polyethylene/wood flour (LDPE/WF) composites are improved when a maleated triblock copolymer styrene–ethylene/butylene–styrene (SEBS–MA) is added as a compatibilizer. The composites' tensile strength reached a maximum level with 4 wt % SEBS–MA content. The compatibilizer had a positive effect on the impact strength and elongation at break but decreased the composites' stiffness. Dynamic mechanical thermal analysis (DMTA), a lap shear adhesion test, and a scanning electron microscope (SEM) were used to investigate the nature of the interfacial adhesion between the WF/SEBS and between the WF/SEBS–MA. Tan δ peak temperatures for the various combinations showed interaction between the ethylene/butylene (EB) part of the copolymer and the wood flour in the maleated system. The shear lap test showed that adhesion between the wood and SEBS–MA is better than between the wood and SEBS. The electron microscopy study of the fracture surfaces confirmed good adhesion between the wood particles and the LDPE/SEBS–MA matrix. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1845–1855, 1998     

Synthesis and thermomechanical characterization of polyurethane elastomers extended with α,ω‐alkane diols

A series of polyurethane (PU) elastomers was prepared by the reaction of poly(?‐caprolactone) and 4,4′‐diphenylmethane diisocyanate, which was extended with a series of chain extenders (CEs) having 2–10 methylene units in their structure. The completion of the reaction was confirmed by Fourier transform infrared spectroscopy. The chemical structures of the synthesized PU samples were characterized with Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR spectroscopy, and the thermal properties were determined by thermogravimetric analysis, DSC, and dynamic mechanical thermal analysis techniques. The mechanical properties were also studied and are discussed. The thermogravimetric analysis and DSC analysis showed that CE length had a considerable effect on the thermal properties of the prepared samples. The dynamic mechanical thermal analysis and damping peaks were also affected by the number of methylene units in the CE length. The elastomer extended with 1,2‐ethane diol exhibited optimum thermal properties, whereas the elastomer based on 1,10‐decane diol displayed the worst thermal properties. Tensile strength and elongation at break decreased with increasing CE length, whereas hardness showed the opposite trend. The glass‐transition temperature moved toward lower temperatures with increasing CE length. The decrease in the glass‐transition temperature and tensile properties were interpreted in terms of decreasing hard segments and increasing chain flexibility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Control of coefficient of thermal expansion in elastomers using boron nitride

The thermal expansion properties of three commercial elastomers; Pebax®, Estane® and Hytrel® modified with 2.5–10 wt % boron nitride were investigated. The glass transition temperatures of the filled materials were relatively unaffected; however boron nitride did effectively reinforce all the three elastomers as seen by dynamic mechanical analysis and tensile tests. The coefficients of thermal expansion of the composite materials do not obey the rule of mixtures and show a large decrease without the loss of ductility typically associated with filled elastomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5153–5161, 2006