Effect of Poly(butyl acrylate)-g-poly(styrene-co-acrylonitrile)’s Core/shell Ratio on Mechanical and Thermal Properties of Poly(butyl acrylate)-g-poly(styrene-co-acrylonitrile)/α-methylstyrene-acrylonitrile Binary Blends

Poly(butyl acrylate)-g-poly(styrene-co-acrylonitrile) terpolymer (PBA-g-SAN) with different core/shell ratios and α-methylstyrene-acrylonitrile (α-MSAN) were mixed via melt blending (25/75, W/W). It was found that the core/shell ratio of PBA-g-SAN played an important role in the toughening of rigid α-MSAN. According to an analysis of the impact strength and the morphologies of the impact fractured surfaces, the optimum core/shell ratio with the highest toughening efficiency was 60/40. Considering the results of dynamic mechanical thermal analysis (DMTA), the blends retained the high glass transition temperature (T_g) of α-MSAN because of the immiscibility between the two components. Moreover, increasing the core/shell ratio did not result in sacrificing the heat distortion temperature of the blends, which was attributed to the almost unchanged high temperature T_g of α-MSAN. The tensile strength, flexural strength, and modulus declined slightly with the increasing core content of PBA-g-SAN, which suggested that the stiffness of the blends decreased with the increasing core/shell ratio. This study showed that 60/40 was the optimum core/shell ratio used for toughening modification; it achieved a good balance between mechanical and heat resistance performance.     

Shear Effect on Morphology of Poly(Butylene Terephthalate)/Poly(Styrene‐co‐Acrylonitrile) Blends

Abstract

The shear flow effect on the morphology of poly(butylene terephthalate)(PBT)/poly(styrene‐co‐acrylonitrile)(SAN) was studied by a parallel plate type shear apparatus. In PBT/SAN = 20/80 blend, particle size of dispersed domains was governed by both break‐up and coalescence processes, and it was much affected by shear rate. The minimum particle size was observed at a certain shear rate. This phenomenon can be explained by the shear matching effect of PBT and SAN; that is, the viscosity ratio of PBT to SAN changed with shear rate and the finest morphology was obtained at the appropriate viscosity ratio. Similar behavior was also observed for PBT/SAN = 70/30 (PBT was the matrix), even though the particle size was larger than that of PBT/SAN = 20/80. For PBT/SAN = 10/90 blend, the sample showed a complicated appearance during shearing. A translucent region correlated to the fine morphology was observed more than twice with increasing shear rate. This phenomenon could not be explained by the viscosity matching effect only. It was affected by small changes in the balance of breaking‐up and coalescence effects.     

Poly(acrylamide‐co‐acrylic acid)/Poly(vinyl pyrrolidone) Polymer Blends Prepared by Dispersion Polymerization

The structure and properties of a three‐component system, a poly(acrylamide‐co‐acrylic acid)/poly(vinyl pyrrolidone) [P(AM‐co‐AA)/PVP] polymer blend prepared by dispersion polymerization, were studied. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the resulting P(AM‐co‐AA) microspheres with diameters between 200–300 nm were well‐dispersed in the PVP matrix. Fourier transform infrared spectra (FTIR) showed that intermolecular hydrogen bonding interaction occurred between the dispersed phase and the continuous phase. The mechanical properties of P(AM‐co‐AA)/PVP polymer blends were also determined. With different mass ratios of acrylamide to acrylic acid, it was found that the blends had better mechanical properties with increased AA content.     

Preparation and Evaluation of the Morphology,Flammability, and Mechanical Properties of the Acrylonitrile‐Butadiene‐Styrene/Poly (vinyl chloride) Blends

Blends of two grades of acrylonitrile‐butadiene‐styrene (ABS) with three different compounds of poly (vinyl chloride) (PVC) were prepared via melt processing and their morphology, flammability, and physical and mechanical properties were investigated. SEM results showed that the ABS/PVC blend is a compatible system. Also, it can be inferred from fracture surface images that ABS/PVC blends are tough, even at low temperatures. It was found that properties of these blends significantly depend on blend composition and PVC compound type; however, the ABS types have only a small effect on blend properties. On blending of ABS with a soft PVC compound, impact strength, and melt flow index (MFI) increased, but tensile and flexural strength decreased. In contrast, blending of ABS with a rigid PVC compound improved fire retardancy and some mechanical properties and decreased MFI and impact strength.     

Hydrogen Bonding Interactions in Miscible Blends of Poly(hydroxyether ester)s with Poly(N‐vinyl pyrrolidone)

Studies on the miscibility and intermolecular specific interactions in the blends of two structurally similar poly(hydroxyether ester)s, poly(hydroxyether terephthalate ester) (PHETE), and poly(hydroxyether benzoate) (PHEB) with poly(4‐vinyl pyrrolidone) (PVPy) are reported. In the miscible blends there are intermolecular specific interactions between PHEEs and PVPy. It was found that intercomponent hydrogen‐bonding interactions in PHETE/PVPy blends are much stronger than those in PHEB/PVPy blends. It seems that the higher ratio of hydroxyl to carbonyl groups results in the stronger intermolecular hydrogen bonding interactions. The difference in intermolecular specific interactions between the two miscible systems is interpreted on the basis of the impact of macromolecular structures on intermolecular specific interactions. The structural characteristics of macromolecular chains, such as chain connectivity, accessibility (or screening effect), and rigidity of the macromolecular chains have a profound effect on the intermolecular interactions. These factors constitute steric hindrance and reduce the specific interactions among functional groups. These factors can become dominant in the blends of polymers.     

Properties of Poly(butylene terephthalate)/Bisphenol A Polycarbonate Blends Toughening with Epoxy-Functionalized Acrylonitrile–Butadiene–Styrene Particles

Glycidyl methacylate functionalized acrylonitrile–butadiene–styrene particles (ABS-g-GMA) prepared via an emulsion polymerization method were used to toughen poly(butylene terephthalate) (PBT)/bisphenol A polycarbonate (PC) blends. DMA results showed PBT was partially miscible with PC and the addition of ABS-g-GMA improved the miscibility between PBT and PC. DSC tests further testified that the introduction of ABS-g-GMA improved the miscibility of PBT and PC according to the T_m depression criterion. SEM displayed a very good dispersion of ABS-g-GMA particles in the PBT/PC blends and the dispersed phase size of PC decreased due to the compatibilization effect of ABS-g-GMA. The mechanical properties showed that the addition of 10 wt% ABS-g-GMA was sufficient to induce a super-tough fracture behavior to the PBT/PC blends and a notched impact strength of more than 1000J/m was achieved. The Vu-Khanh test showed that stable crack propagation took place for PBT/PC blends with the addition of ABS-g-GMA and led to ductile failure.     

Study of Miscibility in Polymer Blends Obtained from Binary Inclusion Complexes of γ-Cyclodextrin and Polycarbonate/Poly(Ethylene Terephthalate)

In this work the synthesis and characterization of the nanostructure of polymer blends of polycarbonate (PC) and poly(ethylene terephthalate) (PET) obtained from their inclusion complexes with γ-cyclodextrin are reported. The blends prepared by this method present differences in their miscibility compared with those blends obtained by conventional methods like solution casting, coprecipitation, or melt blending. In order to understand the influence of molecular weight in the inclusion complex process, PCs of M_w = 64,000 and 28,000 g/mol were used. The analysis of the nanostructured blend by Fourier transform infrared (FTIR), ¹H-nuclear magnetic resonance (¹H-NMR), wide-angle X-ray diffraction (WAXD), differential scanning colorimetry (DSC), and thermogravimetric analysis (TGA) suggests the existence of specific intermolecular interactions between PC and PET that promote miscibility in this normally immiscible polymer blend. Studies by FTIR confirm that the miscibility found was not due to a transesterification reaction during DSC analysis. There were also differences in the morphology of the blends, observed by optical microscopy, obtaining a more homogeneous phase for blends formed in inclusion complexes. The results obtained strongly suggest an improvement in miscibility of the PC/PET blends.     

Study on Phase Formation and Evolution of High Impact Polystyrene with Poly(Cis‐Butadiene) Rubber Blends

Phase formation and evolution of high‐impact polystyrene with poly(cis‐butadiene) rubber blends was studied. The characteristic length, L, was defined to describe the size of particles, and the graph‐estimation method was introduced to determine the width of the distribution of L. Based on the method, the distribution of L proved to be a log‐normal distribution and the distribution width of L was calculated. The phase structure was also discussed in the wave‐number space. The correlation distance, a _c , was defined and computed, applying light‐scattering theory to power spectrum images obtained by 2‐dimensional Fourier transformation (2DFT). The change of a _c was in accord with that of L, which meant 2DFT was valid to study the phase structure. A fractal dimension, D _c , was introduced to describe the uniformity of the spatial distribution. The result showed that D _c was an effective parameter to study the distribution of particles of the dispersed phase.     

Designing and Characterization of Poly(L-Lactide)/Poly(ϵ-Caprolactone) Multiblock Copolymers

A series of poly(L-lactide)/poly(?-caprolactone) (PLA/PCL) biodegradable multiblock copolymers was synthesized by a two-step process and characterized. Ring-opening polymerization was used to prepare a series of HO-PLA-PCL-PLA-OH copolymers initiated by hydroxyl-terminated PCL. Then the triblock copolymers and 1,6-hexamethylene diisocyanate (HDI) were reacted with different copolymer/HDI weight ratios. Consequently, a series of PLA/PCL multiblock copolymers with designed molecular chain structure was obtained. Gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, and ¹H NMR were used to characterize these copolymers and the results showed that the designed PLA/PCL copolymers had been synthesized. Dynamic mechanical analysis (DMA) was applied to characterize their thermal properties. Stress–strain curves showed that a PLA/PCL copolymer with adjustable mechanical properties had been achieved.     

First-Principles Study on Elastic Properties and Electronic Structures of Ti-Based Binary and Ternary Shape Memory Alloys

The elastic properties and electronic structure of B2 phase binary TiM （M =Fe, Co, Ni, Pd, Pt and Au） and ternary TisoNi43.75Pd6.25, TisoNi43.75Cu6.25 shape memory alloys are studied by the plane-wave psedudopotential method within the local density approximation. The elastic constants and density of states are calculated. Our calculations show that the martensitic transformation behaviour of these alloys is closely related to their elastic properties. The Ti d DOS at the Fermi level is mainly responsible for the B2 phase stability of these alloys.     

Effect of Substituents and Dopants on the Structure–Property Relationship of Poly(Aniline)—A Comparative Study

Effects of substituents and dopants on the structure–property relationships of poly(aniline) (PANI)-type homopolymers are analyzed. The gravimetric method was used for the estimation of rate of polymerization (R_p). FTIR spectroscopy was used for the calculation of relative intensities (RI) of benzenoid (RI_[B/CH]), quinonoid (RI_[Q/CH]), and their internal conversion (RI_[B/Q]). Thermogravimetric analysis (TGA) characterized the thermal stability of PANIs. A standard four probe method was employed for the conductivity measurements. The results are analyzed and critically compared.     

Apatite formation on Poly (vinyl alcohol)-coated Poly (?-caprolactone) films by incubation in simulated body fluids

In this study, biodegradable poly (?-caprolactone) (PCL) films were coated with poly (vinyl alcohol) (PVA) and then incubated in a simulated body fluid 1.5SBF to prepare an apatite (HA)/PCL composite. It was found that the bone-like apatite formability of PCL was enhanced by PVA coating. The changes of surface properties induced by PVA coating were effective for apatite formation. The apatite formability increased with increasing coating amount. After 24 h incubation, apatite was formed on PVA-coated PCL film but hardly any apatite was found on uncoated PCL plate. The surface chemistry of the specimens was examined using XPS, FT-IR-ATR. The apatite formed was characterized by using SEM, TF-XRD, FT-IR, EDS. The apatite formed was similar in morphology and composition to that of natural bone. This indicated that simple PVA coating on PCL substrate could serve as a novel way to accelerated apatite formation via biomimetic method.     

Study of Properties of Urea and L-α-Alanine Didoped Triglycine Sulfate (UrLATGS) Crystals

In this report, the properties of triglycine sulfate (TGS) crystals doped with urea and L--alanine were studied. Urea and L--alanine have successfully entered into TGS crystal, demonstrated by infrared transmission spectrum and pyroelectric study. Figures of merit and Curie temperature are increased due to these two additions. UrLATGS is more suitable for infrared detectors than pure TGS crystals.     

Effects of Molecular Weight on Thermal Degradation of Poly(α-methyl styrene) in Nitrogen

The effects of molecular weight on the thermal degradation behavior of poly(α-methyl styrene) (PAMS) was investigated by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and thermogravimetric analysis (TGA). The Py-GC/MS analysis results showed that the degradation of PAMS with different molecular weights in nitrogen produced only the monomer, alpha-methylstyrene. The TGA results showed a pronounced reduction in the decomposition temperature with increasing molecular weight. The degradation kinetic parameters, calculated by the Kissinger and the Coats–Redfern methods, further revealed that the activation energy and the pre-exponential factor decreased with increasing molecular weight. Most importantly, the degradation order of the PAMS in nitrogen remained around 1, independent of the molecular weight, suggesting the maintenance of the depolymerization mechanism. All the above results provided an insight into the effects of molecular weight on the thermal degradation behavior of PAMS.     

Mechanical and Morphological Properties and Deformation Mechanisms of Acrylonitrile-Butadiene-Styrene/Poly(ϵ-Caprolactone) Blends with Varied Matrix Composition

Acrylonitrile-butadiene-styrene and poly(?-caprolactone) blends (ABS/PCL) were prepared by mixing styrene-co-acrylonitrile (SAN), polybutadiene-g-SAN (PB-g-SAN), and PCL with varied SAN and PCL composition. PCL is miscible with SAN and can improve the matrix toughness. The impact strength and elongation at break of the ABS/PCL blends increased with the PCL content. When the PCL content was lower than 20 wt%, the improvement of impact strength for the blends was not obvious. A significant increase of impact strength took place when the PCL content was between 20 and 25 wt%. When PCL content was more than 20 wt%, the impact strength was higher than 800 J/m which shows the super toughness. The addition of PCL improved the dispersed phase morphology of PB-g-SAN in the matrix and the interfacial adhesion increased. Deformation observations showed that, when the PCL content was lower than 20 wt%, crazing was the major deformation mode. When the PCL content was 20 wt%, crazing and slight shear yielding could be found. When the PCL content was more than 20 wt%, cavitation of rubber particles and shear yielding of the matrix were the major deformation modes. The cause of the change of the deformation mode lies in the varied matrix composition which modifies the crazing and yielding stresses of the matrix and the final fracture mode and impact toughness.     

Micromechanical Behavior and Glass Transition Temperature of Poly(Methyl Methacrylate)–Rubber Blends

Abstract

The microhardness of transparent rubber‐toughened poly(methyl methacrylate) (RTPMMA) was investigated by means of the microindentation technique. Core‐shell particles (CSP) with a rubbery shell were used as reinforcing material for the production of RTPMMA. The increasing volume fraction of CSP within the poly(methyl methacrylate) (PMMA) matrix is shown to soften the material, diminishing the hardness (H) value of RTPMMA of about 40% of the initial value at 35 vol% CSP content. Creep experiments under the indenter are reported. The creep constant is found to increase by adding CSP up to a leveling‐off value. On the other hand, the thermal variation of the creep constant for the blends shows a maximum. Results reveal a good correlation of the glass transition temperature (T _g) value deduced from microindentation, and the values obtained from differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) techniques. Contrary to expectation H is shown to decrease with increasing glass transition temperature. In the case of the drawn materials, the indentation anisotropy is shown to gradually increase with draw ratio and CSP content. This finding is explained on the basis of the higher orientation of the PMMA molecules near the periphery of CSP.     

Luminescence Properties of Poly(3-Methoxythiophene)—Bithiophene Composite Oligomers

The electronic absorption and fluorescence spectra of electrosynthesized poly(3-methoxythiophene)— bithiophene (PMOT-BT) composite oligomers were studied in organic solution (DMSO) and/or in the solid state on ITO plates. Different spectral properties (absorption and fluorescence maximum wavelengths, fluorescence quantum yields, etc.) were found to depend on the bithiophene initial concentration used during electrosynthesis and, subsequently, on the film composition and oligomer chain length.     

Effects of Poly(Propylene Oxide)–Poly(Ethylene Oxide)–Poly(Propylene Oxide) Triblock Copolymer on the Gelation of Poly(Ethylene Oxide)–Poly(Propylene Oxide)–Poly(Ethylene Oxide) Aqueous Solutions

Poly(ethylene oxide)-poly(propylene oxide)–poly(ethylene oxide) ((EO)_n–(PO)_m–(EO)_n) block copolymers, commercially available as Pluronics (BASF Corp.) and Poloxamers (ICI Corp.), have been widely applied in medicine, biochemistry, and other fields because of their ability to form reversible micelles and physical gels in aqueous solution. Generally, for PEO–PPO–PEO block copolymers with higher ethylene oxide concentration, the micellization and gelation in aqueous solution are easier. However, if we introduce the reverse block copolymer PPO–PEO–PPO into PEO–PPO–PEO aqueous solutions, the micellization and gelation of the system will be more complex. In this work, the reverse block copolymer PO₁₄–EO₂₄–PO₁₄ (17R4) was added to the Pluronics EO₂₀–PO₇₀–EO₂₀ (P123), EO₁₀₀–PO₆₅–EO₁₀₀ (F127), and EO₁₃₃–PO₅₀–EO₁₃₃ (F108) aqueous solutions with different molar ratios. The rheological properties of different mixtures were measured to study the additive effect on the gelation behavior. The sol–gel transition temperature of the P123, F127, and F108 solutions shifted to a higher temperature when 17R4 was added to the solutions. In addition, the existence of 17R4 greatly affected the stability of gels. These results help to better understand the gelation of Pluronic aqueous solutions.     

Nonisothermal Crystallization Nucleation of In‐Situ Fibrillar and Spherical Inclusions in Poly (Phenylene Sulfide)/Isotactic Polypropylene Blends

Nonisothermal crystallization nucleation and its kinetics of in‐situ fibrillar and spherical dispersed phases in poly (phenylene sulfide) (PPS)/isotactic polypropylene (iPP) blends are discussed. The PPS/iPP in‐situ microfibrillar reinforced blend (MRB) was obtained via a slit‐die extrusion, hot stretching, and quenching process, while PPS/iPP common blend with spherical PPS particles was prepared by extrusion without hot stretching. Morphological observation indicated that the well‐defined PPS microfibrils were in situ generated. The diameter of most microfibrils was surprisingly larger than or equal to the spherical particles in the common blend (15/85 PPS/iPP by weight). The nonisothermal crystallization kinetics of three samples (microfibrillar, common blends, and neat iPP) were investigated with differential scanning calorimetry (DSC). The PPS microfibrils and spherical particles could both act as heterogeneous nucleating agents during the nonisothermal crystallization, thus increasing the onset and maximum crystallization temperature of iPP, but the effect of PPS spherical particles was more evident. For the same material, crystallization peaks became wider and shifted to lower temperature when the cooling rate increased. Applying the theories proposed by Ozawa and Jeziorny to analyze the crystallization kinetics of neat iPP, and microfibrillar and common PPS/iPP blends, both of them could agree with the experimental results.