Properties and Application of a Novel Type of Glycidyl Azide Polymer (GAP)‐Modified Nitrocellulose Powders

GAP‐modified nitrocellulose powders were prepared by an internal solution method and applied in cross‐linked modified double base (XLDB) propellants. It was found that GAP‐modified nitrocellulose powders exhibit high round, no bonding between the particles and excellent fluidity. When the amount of GAP increased from 10.0 % to 30.0 %, the median diameter (d₅₀) of powders decreased from 134.53 μm to 94.54 μm. The thermal decomposition process of GAP appeared also in the GAP‐modified nitrocellulose powders, but the thermal decomposition peak temperatures of  N₃ and the GAP main chain were found to be lower for the 10.0 % and 20.0 % GAP‐modified samples than the corresponding peak temperatures for pure GAP, respectively. The plasticizing properties of GAP‐modified nitrocellulose powders are better than that of pure nitrocellulose powders, and the drop weight impact sensitivity of the modified powders is reduced as the mass ratio of GAP increases. It was experimentally shown that GAP‐modified nitrocellulose powders can improve the mechanical characteristics of the propellant with a maximum tensile strength (σ_m) between 0.36 MPa<σ_m< 1.10 MPa and an elongation at maximum tensile strength (ε_m) between 28.8 %<ε_m<51.8 % at temperatures of −40, +20 and +50 °C.     

Study on the Synthesis and Interfacial Interaction Performance of Novel Dodecylamine‐Based Bonding Agents Used for Composite Solid Propellants

An effective pathway was explored to design and select proper bonding agents that could effectively improve the interfacial interactions between bonding agents and solid particles, with three novel synthesized alkyl bonding agents, dodecylamine‐N,N‐di‐2‐hydroxypropyl‐acetate (DIHPA), dodecylamine‐N,N‐di‐2‐hydroxypropyl‐hydroxy‐acetate (DIHPHA) and dodecylamine‐N,N‐di‐2‐hydroxypropyl‐cyano‐acetate (DIHPCA), as examples. Molecular dynamics simulation was applied to compare unit bond energies of these bonding agents with the [110] crystal face of ammonium perchlorate (AP) and the [120] crystal face of hexogen (RDX). The infrared test was used to characterize the interfacial interactions of these bonding agents with AP or RDX. XPS test was applied to calculate the adhesion percentage of the bonding agents on the surface of precoated AP or RDX particles. All of the above results indicated that these three bonding agents have strong interfacial interactions with AP or RDX in the order of DIHPCA>DIHPHA>DIHPA. The prepared three bonding agents were used in HTPB/AP/RDX/Al propellants, and their effects on tensile strength (σ), elongation under maximum tensile strength (ε_m), elongation at breaking point of the propellant (ε_b) and adhesion index (Φ) of the propellant were studied. The results show that the bonding agents improve the mechanical properties of the propellant in the order of DIHPCA>DIHPHA>DIHPA. The methods found from theoretical design, materials synthesis, and mechanistics studies up to practical application show effective guiding significance for choosing the proper bonding agent and improving the interfacial interactions between the solid particles and binder matrix.     

Synthesis of Three Novel Laurylamine‐Derived Long‐Chain Alkyl Bonding Agents and Their Interactions with RDX

Three novel long‐chain alkyl bonding agents including 1,1′‐dodecylimino‐bis[3‐[bis(2‐hydroxyethyl)amino]‐2‐propanol (DHAP), 1‐acetyl‐5‐dodecyl‐octahydro‐1,5‐diazocine‐3,7‐diol (ADODD) and 1,3‐bis(dodecylimino)‐5,5‐dimethyl‐2,4‐imidazolidinedione (DDID) were synthesized by modification of laurylamine. Interaction energies between bonding agents and RDX were calculated and compared using the molecular dynamics method. Effects of coating by different bonding agents on characteristic absorption peaks of RDX were analyzed by micro‐infrared spectroscopy. The adhesion degrees of different bonding agents on the surface of RDX solid particles were calculated by XPS methods. The three prepared bonding agents were added to the HTPB/RDX/Al propellant and their effects on σ, ε_m, ε_b and Φ (the adhesion index between filling particles and binder matrix) value of propellant were studied. Simulation and experimental results showed that those three types of long‐chain alkyl bonding agents exhibit a strong interaction with RDX, with highest interaction potencial observed for DHAP, followed by DDID and ADODD. In addition, the current study demonstrated that results obtained by molecular dynamics simulation were in very good agreement with the experimental data.     

Preparation and Properties of a nRDX‐based Propellant

The incorporation of nano‐scaled cyclotrimethylene trinitramine (nRDX) in nitrocellulose (NC)‐based propellants poses processing problems when following conventional methods. Hence, a new preparation method containing a pre‐dispersion process was developed, by which 30 mass % RDX (290 nm) was incorporated in the propellant. Meanwhile, the corresponding 290 nm, 12.85 μm and 97.76 μm RDX‐based propellants were prepared for comparison using a conventional method. The morphology, structure, ballistic and mechanical properties of the prepared propellants were characterized by scanning electron microscopy (SEM), density analyzer, closed vessel (CV), uniaxial tensile tester and impact tester. The results indicate that the nRDX particles were uniformly dispersed in the NC/NG/TEGDN matrix using the novel method, while agglomerated and recrystallized into large particles with the conventional method. The propellant density increased with decreasing RDX particle size. In particular, the 290 nm RDX‐based propellant exhibited a higher burning rate and lower average pressure exponent (α =0.958) compared to the 12.85 μm RDX‐based propellant (α =1.043). The tensile strength, elongation at break and impact strength of the RDX‐based propellant at −40 °C, 20 °C and 50 °C were dramatically improved by using 290 nm RDX with the novel method.     

Combustion Effects of Nitrofulleropyrrolidine on RDX‐CMDB Propellants

The effect of N‐methyl‐2‐(3‐nitrophenyl)pyrrolidino[3′,4′:1,2]fullerene (mNPF) on the decomposition characteristics of hexogen (RDX) was investigated using differential scanning calorimetry (DSC). The results show that mNPF can accelerate the decomposition of RDX, the peak temperature (T_p) of the exothermal decomposition is reduced by 6.4 K, and the corresponding apparent activation energy (E_a) is decreased by 8.7 kJ mol⁻¹. N‐methyl‐2‐(3‐nitrophenyl)pyrrolidino[3′,4′:1,2]fullerene (mNPF), carbon black (CB), and C₆₀ were used as combustion catalysts to improve the combustion performance of a composite modified double‐base propellant containing RDX (RDX‐CMDB). The burning rate experimental results show that mNPF has a stronger catalytic effect than C₆₀ and CB. The magnitude of the effect of the three carbon substances on the enhancement of the burning rate is as follows: mNPF>C₆₀>CB. The catalytic effects of different contents of mNPF on the burning rates of RDX‐CMDB propellants were also studied, and the results show that the burning rates of RDX‐CMDB propellants are improved with increasing mNPF content. The plateau burning rate of a RDX‐CMDB propellant can be increased to 19.6 mm s⁻¹ when 1.0 % mNPF is added, and the corresponding plateau combustion region occurs at 8–22 MPa.     

Atomistic insight into ideal strength,fracture toughness,deformation, and failure mechanisms of magnetocaloric Fe2AlB2

The thermal and magnetic cycling of a magnetocaloric material degrades its mechanical properties and device performance. We used ab initio tensile and shear simulations to investigate the mechanical properties such as ideal strength, fracture toughness and deformation and failure mechanisms of Fe₂AlB₂ at finite strain. The weakest direction of Fe₂AlB₂ is [010], and the weakest slip system is (010)[100]. The ideal tensile strength (σ_m = 12.51 GPa) of Fe₂AlB₂ is less than its ideal shear strength (τ_m = 13.32 GPa). The strain energy difference (ΔE = −13 eV/f.u.) of Fe₂AlB₂ confirms cleavage fracture as its most plausible failure mode. The concomitant changes in the c-lattice parameter and Al–Al bond along the c-axis determine the ideal tensile strength of Fe₂AlB₂. Likewise, the subtle changes in the a-lattice parameter and Al–Al bond along the a-axis specify its ideal shear strength. The tensile strain induces a magnetic to nonmagnetic transition in Fe₂AlB₂ at the critical tensile strain (ε_c = 0.08). A similar transition occurs at the critical fracture strain (ε_cf = 0.48) due to shear deformation. The brittle nature of Fe₂AlB₂ is predicted by its anisotropic Poisson's ratios, strength ratio, and failure mode. The fracture toughness of Fe₂AlB₂ for mode I fracture is (K_Ic = 2.17 MPa m^1/2), mode II fracture is (K_IIc = 1.33 MPa m^1/2), and mode III fracture is (K_IIIc = 1.16 MPa m^1/2). The failure mechanism of Fe₂AlB₂ due to the tensile deformation is marked by the sharp and appreciable changes in the lattice parameters, bonding characteristics, and magnetic moment of Fe at the critical fracture strain (ε_cf = 0.44). This study provides a fundamental understanding of the mechanical behavior of Fe₂AlB₂ at the finite strain relevant to the cycling stability of the magnetocaloric Fe₂AlB₂.     

Frequency and voltage dependence of dielectric properties,complex electric modulus,and electrical conductivity in Au/7% graphene doped‐PVA/n‐Si (MPS) structures

In order to increase the capacitance of Au/n‐Si (MS) structure, 7% graphene doped PVA was coated on n‐Si as an interfacial layer. The measured data of capacitance (C) and conductance (G/ω) of Au/7% graphene doped‐PVA/n‐Si (MPS) structure was utilized for the calculation of real and imaginary parts of complex permittivity (ε^* = ε′ − jε″), loss tangent (tanδ), complex electric modulus (M^* = M′ + jM″), and electrical conductivity (σ). The admittance measurements (C and G/ω) were carried out in the frequency range of 0.5 kHz to 1 MHz at room temperature. Frequency dependence of the dielectric constant (ε′), dielectric loss (ε″) and tanδ shows a dispersive behavior at low frequencies. This behavior was explained by Maxwell–Wagner relaxation. Due to the dipolar and the interfacial polarizations, as well as the surface states (N_ss) and the interfacial PVA layer, the parameters exhibited a strong dependence on frequency and applied bias voltage. The σ versus log(f) plot exhibited both low and high frequency dispersion phenomena such that at low frequencies σ value corresponding to the dc conductivity (σ_dc), but at high frequencies it corresponds to the ac conductivity (σ_ac). M′ and M″, both, have low values in the low frequency region. However, an increase is observed with the increasing frequency due to the short‐range mobility of charge carriers. As a result, the change in dielectric parameters and electric modulus with frequency is the result of relaxation phenomena and surface states. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43827.     

Synthesis,Characterization, and Combustion Catalytic Activities of Copper(II) and Lead(II) Salts of p‐Nitrocalix[n]arenes (n=4, 6, 8)

Six copper(II) and lead(II) salts of p‐nitrocalix[n]arene (n=4, 6, 8) were synthsized and characterized. The DSC curves of all salts showed exothermic decomposition. Sensitivity studies revealed that all the salts with the exception of the lead salt of p‐nitrocalix[6]arene (NCPb6) are relatively insensitive materials. Investigations of the catalytic activities showed that most of the salts displayed high activities in thermal decomposition of NC‐NG and RDX. As evaluated in this work, the salts enhanced the burning rates of both double base (DB) and RDX‐component modified double base propellants. The best catalytic effect was obtained with NCPb6, which increased the burning rate of the DB propellant to the order of about 200 % (2–6 MPa) and 103–198 % (8–20 MPa) while decreasing the pressure index (n) to 0.22 (20–22 MPa).     

Multiwalled carbon nanotube‐filled ethylene acrylic elastomer nanocomposites: Influence of ionic liquids on the mechanical,dynamic mechanical,and dielectric properties

Electrically conductive nanocomposites based on ethylene acrylic elastomer (AEM) and multiwalled carbon nanotube (MWNT) have been successfully prepared. Before mixing the MWNT is dispersed in ethanol in presence of ionic liquids such as 1‐methyl‐3‐octylimidazolium chloride (MOIC) and 1‐allyl‐3‐methyl imidazolium chloride (AMIC). Uniform dispersion of MWNT in the nanocomposites is achieved in presence of ionic liquid, which is confirmed by the high‐resolution transmission electron microscopic (HRTEM) microphotographs. The tensile strength increases up to 6 phr of MWNT loading and above that it decreases. However, the tensile strength increases due to the incorporation of ionic liquid assisted dispersed MWNT. It is observed from the dynamic mechanical analysis (DMA) that the storage modulus (E′) and glass transition temperature (T_g) of AEM matrix increase by incorporation of MWNT. The E′ also increases and the tan δ_max marginally decreases due to the incorporation of dispersed MWNT in presence of ionic liquids. The dielectric relaxation characteristic properties of AEM/MWNT nanocomposites such as dielectric permittivity (ε′), AC conductivity (σ_ac), impedance (Z^*) have been studied as a function of frequency (10¹−10⁶ Hz) in presence of ionic liquids. The ε′ and σ_ac increase with increasing the MWNT loading due to the easy orientation of dipoles and formation of interconnected conductive networks in the nanocomposites. The electromagnetic interference shielding effectiveness (EMISE) is studied in the X‐band frequency range of 8 to 12 GHz, which significantly improved with increase in MWNT loading. POLYM. COMPOS., 37:2568–2580, 2016. © 2015 Society of Plastics Engineers     

Application of the BAMO‐AMMO Alternative Block Energetic Thermoplastic Elastomer in Composite Propellant

A BAMO‐AMMO alternative block (BAAB)‐based thermoplastic composite propellant with 80 % solid content was prepared using BAAB energetic thermoplastic elastomer (ETPE) as the binder, and the formulation was optimized through energy calculation. The densities, heats of explosion, glass‐transition temperatures, and mechanical properties of the samples were determined by surface tension measurements, oxygen bomb calorimetry, differential scanning calorimetry and static tensile tests, respectively. The results showed that this composite propellant can reach a standard theoretical specific impulse of 275.45 s (10 MPa), a density of 1.8102 g cm⁻³, a heat of explosion of 6256 kJ kg⁻¹, a T_g of −50.46 °C, a tensile strength of 1.56 MPa and an elongation at break of 20 %, thus presenting a superior comprehensive property to BAMO‐AMMO random block (BARB)‐based thermoplastic composite propellant.     

Multiscale Simulation on the Influence of Dimethyl Hydantoin on Mechanical Properties of GAP/RDX Propellants

The influence of dimethyl hydantoin (DMH) on the mechanical properties of GAP/RDX propellant was studied by molecular dynamics (MD) and dissipative particle dynamics (DPD) simulation. The results showed that the binding energies (E_binding) between GAP and different surfaces of RDX were in the order of (010)>(001)>(100). Compared to GAP/RDX, GAP grafted with DMH (GAP‐DMH) exhibits higher binding energies with RDX, and the sequence of E_binding turns to (001)>(010)>(100). Radial distribution simulations demonstrated that GAP‐DMH is more close to the surfaces of RDX, increasing the van der Waals energies between GAP‐DMH and RDX. The stress and strain of GAP‐DMH/RDX excel those of GAP/RDX. DPD simulations showed that GAP‐DMH was able to restrain the agglomeration of RDX, to improve the dispersibility and to enlarge the contact surface with RDX, which also increased the mechanical properties of GAP/RDX propellant.     

Maxwell Fluid Model for Generation of Stress–Strain Curves of Viscoelastic Solid Rocket Propellants

Solid rocket propellants are modeled as Maxwell Fluid with single spring and single dashpot in series. Complete stress–strain curve is generated for case‐bonded composite propellant formulations by taking suitable values of spring constant and damping coefficient. Propellants from same lot are tested at different strain rate. It is observed that change in spring constant, representing elastic part is very small with strain rate but damping constant varies significantly with variation in strain rate. For a typical propellant formulation, when strain rate is varied from 0.00037 to 0.185 per second, spring constant (K) changed from 5.5 to 7.9 MPa, but damping coefficient (D) varied from 1400 to 4 MPas. For all strain rates, stress–strain curve is generated using developed Maxwell model and close matching with actual test curve is observed. This indicates validity of Maxwell fluid model for case‐bonded solid propellant formulations. It is observed that with increases in strain rate, spring constant increases but damping coefficient decreases representing solid rocket propellant as a true viscoelastic material. It is also established that at higher strain rate, damping coefficient becomes negligible as compared to spring constant. It is also observed that variation of spring constant is logarithmic with strain rate and that of damping coefficient follows a power law. The correlation coefficients are introduced to ascertain spring constants and damping coefficients at any strain rate from that at a reference strain rate. Correlation for spring constant needs a coefficient “H,” which is function of propellant formulation alone and not of test conditions and the equation developed is K₂=(K₁‐H)×{ln(dε₂/dt)/ln(dε₁/dt)}+H. Similarly for damping coefficient (D) also another constant “S” is introduced and prediction formula is given by D₂=D₁×{(dε₂/dt)/(dε₁/dt)}^S. Evaluating constants “H” and “S” at different strain rates validate this mathematical formulation for different propellant formulations. Close matching of test and predicted stress–strain curve indicates propellant behavior as viscoelastic Maxwell Fluid. Uniqueness of approach is to predict complete stress–strain curves, which are not attempted by any other researchers.     

Analysis for Decomposition Characteristics and Piecewise Thermokinetics of Nitramine Modified Double‐base Propellant with High Solid Content

The thermal stability and decomposition characteristic of nitramine modified double‐base propellant (RDX‐CMDB propellant) with high solid content and its components were investigated under dynamic and isothermal conditions by differential scanning calorimetry (DSC). It was found that the mixture of nitrocellulose (NC) and nitroglycerin (NG) had a promote effect on the decomposition of RDX. The activation energy (E ) and the pre‐exponential factor (A ) of two obviously exothermic processes were obtained by Friedman iso‐conversional method. The screening method suggested by ICTAC was used to determine the most probable mechanism functions and kinetic parameters of the two processes which are corresponding to the deceleration model and the autocatalytic model. The theoretical value was consistent with the experiment result.     

Structural evaluation and mechanical property of boron nitride fibers during melt‐drawn fabrication process

Boron nitride (BN) fibers were fabricated on a large scale through the melt‐drawn technique from low‐cost boric acid, NH₃, and N₂. Evolution of structure and properties of BN fibers during the fabrication process was studied by Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), scanning electron microscope (SEM), and X‐ray photoelectron spectroscopy (XPS). The mechanical properties of BN fibers were tested and analyzed. The results shown that both the mechanical properties and the crystallinity of BN fibers slightly increased with the temperature from 450 to 850°C, due to the combination of the fused‐B₃N₃. For BN fibers heat‐treated at 850 or 1000°C, the tensile strength (σ^R) and elastic modulus (E) were strongly increased because of the increase in crystallization of the BN phase. The meso‐hexagonal BN fibers with a diameter of 5.0 μm were fabricated at 1750°C, of which the tensile strength (σ^R) and elastic modulus (E) are 1200 MPa and 85 GPa, respectively. BN fibers with excellent mechanical properties and proper diameters were obtained by nitriding of green fibers during their conversion into ceramic.     

Properties and structural characterization of oxidized starch/PVA/α‐zirconium phosphate composites

Two series of composites, i.e., polyvinyl alcohol (PVA)/oxidized starch (OST)/exfoliated α‐zirconium phosphate (POST‐ZrPn) and PVA/starch (ST)/exfoliated α‐zirconium phosphate (PST‐ZrPn), were fabricated using a casting and solvent evaporation method. The composites were characterized by Fourier transform infrared spectroscopy (FT‐IR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (XRD), scanning electron microscopy (SEM), tensile testing, and moisture uptake. Compared with PST‐ZrPn, POST‐ZrPn films with the same component ratio showed higher tensile strength (σ_b), lower elongation at break (ε_b) and improved water resistance. Additionally, in the POST‐ZrPn series, σ_b and ε_b increased with an increase in α‐zirconium phosphate (α‐ZrP) loading; however, higher α‐ZrP loads resulted in the aggregation of α‐ZrP particles. Compared with POST‐ZrP0, the values for σ_b, ε_b, and water resistance of POST‐ZrP3, containing 1.5 wt % α‐ZrP, were increased by 128.8%, 51.4%, and 30.2%, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of molecular weight and arm number on properties of star‐shape styrene–butadiene–styrene triblock copolymer

A star‐shape styrene–butadiene–styrene triblock copolymer SBS (802) was synthesized and fractionated into four fractions coded as 802‐F1 (four arms), 802‐F2 (two arms), 802‐F3 (one arm), and 802‐F4 by repeating fractional precipitation. Their weight‐average molecular weight (M_w) was measured by size‐exclusion chromatography combined with laser light scattering to be 16.0 × 10⁴, 8.2 × 10⁴, 4.3 × 10⁴, and 1.19 × 10⁴, respectively. The samples were, respectively, compression‐molded and solution‐cast to obtain the sheets coded as 802C, 802‐F1C, 802‐F2C, and 802S, 802‐F1S, 802‐F2S. The structures and mechanical properties of the sheets were characterized by ¹H‐NMR, scanning electron microscope, wide‐angle X‐ray diffractometer, tensile testing, and dynamic mechanical thermal analysis. The results indicated that the compression‐molded 802‐F1C exhibited the higher tensile strength (σ_b, 28.4 MPa) and elongation at break (ε_b, 1610%), and its optical transmittance is much higher than those of 802C and 802‐F2C. This work revealed that the star‐shape SBS with four arms could be helpful in the enhancement of the properties as a result of good miscibility of the compression‐molded SBS sheets. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 832–840, 2005     

Optical Properties of Energetic Materials: RDX,HMX, AP,NC/NG,and HTPB

Optical properties of RDX, HMX, AP, HTPB/IPDI and a catalyzed NC/NG propellant (N5) were obtained from 2.5 μm to 18 μm using FTIR transmission spectrometry. Scattering-corrected KBr pellet methodology was used for the crystalline materials. Absorption index (k) was measured directly and refractive index (n) was deduced using dispersion theory. At 10.600 μm the absorption coefficients were AP, 190 cm⁻¹ (240 cm⁻¹ at 10.6036 μm); HTPB/IPDI, 360 cm⁻¹; N5, 510 cm⁻¹; RDX, 2800 cm⁻¹; and HMX, 5670 cm⁻¹.     

Low‐Temperature Spark Plasma Sintering of Pure Nano WC Powder

For the first time we have demonstrated the densification of high‐purity nanostructured (d_avg ≈ 60 nm) tungsten carbide by High Pressure Spark Plasma Sintering (HPSPS) in the unusually low temperature range of 1200°C–1400°C. The high‐pressure sintering (i.e., 300 MPa) produced dense material at a temperature as low as 1400°C. In comparison with more conventional sintering techniques, such as SPS (80 MPa) or hot isostatic pressing, HPSPS lowered the temperature required for full densification by 400°C–500°C. High Pressure Spark Plasma Sintering, even in absence of any sintering aid or grain growth inhibitor, retained a very fine microstructure resulting in a significant improvement in both hardness (2721 HV₁₀) and fracture toughness (7.2 MPa m^1/2).     

Effect of polyphenylene sulfide containing amino unit on thermal and mechanical properties of polyphenylene sulfide/glass fiber composites

Three kinds of high‐molecular‐weight compatibilizers [copoly(1,4‐phenylene sulfide)‐poly(2,5‐phenylene sulfide amine)] (PPS‐NH₂) containing different proportions of amino units in the side chain) were synthesized by the reaction of dihalogenated monomer and sodium sulfide via nucleophilic substitution polymerization under high pressure. The intrinsic viscosity of the obtained copolymers was 0.354–0.489 dL/g and they were found to have good thermal performance with melting point (T_m) of 271.3–281.0 °C and initial degradation temperature (T_d) of 490.0–495.7 °C. There was an excellent physical compatibility between PPS‐NH₂ and the pure industrial PPS. The results of dynamic mechanical analysis and macro‐ and micromechanical test showed that the selective compatibilizer PPS‐NH₂ (1.0) (1.0% mol aminated ratio) can improve the mechanical and interfacial properties of polyphenylene sulfide/glass fiber (PPS/GF) composite. The macro‐optimal tensile strength, Young's modulus, bending strength, and notched impact strength of 5%PPS‐NH₂ (1.0)/PPS/GF composite raised up to 141 MPa, 1.98 GPa, 203 MPa, and 6.15 kJ/m², which increased 12.8%, 9.4%, 4.1%, and 13.8%, respectively, comparing with the pure PPS/GF composite (125 MPa, 1.81 GPa, 195 MPa, and 5.40 kJ/m², respectively). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45804.     

Preparation and characterization of soy protein plastics plasticized with waterborne polyurethane

Utilizing anionic waterborne polyurethane (WPU) as a plasticizer, for the first time, we prepared new soy protein isolate (SPI) plastics. The WPU was prepared by using the emulsion‐extending‐chain method, and mixed with soy protein in aqueous dispersion. The mixture was cast, cured, pickled and hot‐pressed to form SPI plastics plasticized with WPU. The plastics sheets were characterized by infrared spectroscopy, scanning electron microscopy, ultraviolet spectrophotometry and wide‐angle X‐ray diffraction, and their properties were measured by using dynamic mechanical analysis, differential scanning calorimetry and tensile testing. The results revealed that SPI plastics plasticized with WPU possess good mechanical properties, such as a tensile strength (σ_b) of 7–19 MPa, water resistance (σ_b(wet)/σ_b(dry) = 0.4–0.5), optical transmittance and thermal stability, because of the good miscibility and strong interaction between WPU and SPI. With an increase of WPU content from 20 to 50 wt%, the elongation at break (ε_b) value of the sheets increased from 50 up to 150 %, and is much higher than that of the pure SPI sheet. WPU as a plasticizer can play an important role in improving the properties of SPI plastics. Copyright © 2004 Society of Chemical Industry