Structural Orientations of Cellulose Acetate Phthalate/Ethyl Cellulose Blends in Solution

Cellulose acetate phthalate/ethyl cellulose blends were investigated by means of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetry/differential thermal analysis (TGA-DTGA), shear viscosity and oscillatory shear tests. The studies showed a higher thermal stability, induced by the occurrence of hydrogen bonding, more predominant in ethyl cellulose and blends with higher content of ethyl cellulose. The effect of solution concentrations in N,N-dimethylacetamide, blend compositions and shear rate on the rheological functions generated regions with properties typical for liquid crystalline solutions in the shear field. These studies are suggested to be useful in identification of liquid crystal properties, required in some electrotechnical applications.     

Solution Behavior of Hydrophobic Cationic Hydroxyethyl Cellulose

The hydrophobic cationic hydroxyethyl cellulose (HEC-g-DA) was prepared by grafting HEC with various alkyl ammonium chlorides (DA) in order to improve the thickening properties of cationic hydroxyethyl cellulose. The solution behavior of HEC-g-DA was studied, and showed that the apparent viscosity of HEC-g-DA increased with polymer concentration, and there existed a critical association concentration (Cp*). The alkyl chain length of DA had a great influence on Cp*, which decreased with increasing alkyl chain length; however, too long an alkyl chain of DA reduced the water solubility of the polymer, resulting in a slight increase of Cp*. The effect of temperature and electrolyte concentration on the thickening properties of HEC-g-DA was investigated; the value of viscous flow activation energy (E_a) was minimum for the sample of HEC-g-DA16 (glycidyl-N-hexadecyl–N,N-dimethyl-ammonium chloride), indicating the weakest sensitivity of the viscosity to temperature. In the whole range of shear rate investigated, the solutions of HEC-g-DA displayed the shear thinning behavior of a pseudoplastic fluid. The values of viscous index (n) from the Ostwald model simulation decreased with polymer concentration, indicating an improvement of the shear thinning property of the solution, whereas the increase of the consistency coefficient (k) indicated the enhancement of the thickening behavior of the polymer. With increasing polymer concentration, the molecular association of HEC-g-DA16 became strong, and high-shear stress was required to remove the association, while the difference between G′ and G″ became small, indicating that the elasticity of the system was enhanced at high polymer concentration. The amphiphilic structure of the HEC-g-DA16 molecules contributed to the low surface tension of the polymer.     

Solution blends of polyacrylonitrile with segmented polyurethanes: Effect of soft segments

Solution blends of a modified polyacrylonitrile (PAN) with polyurethane (PU) obtained from 4, 4′-diphenylmethane diisocyanate (MDI) and two different types of polyols– i.e., ether-linked polytetramethylene ether glycol (PTEG) and ester-linked polytetramethylene adipate glycol (PTAG) – were prepared in N, N-dimethylformamide (DMF). The domains in the PTAG-PU blends were much finer than those in the PTEG-PU blends. Shift of the soft segment transition temperatures (T _gs) of PU toward lower temperature with increasing PAN was more significant for PTAG-PU blends. Miscibility was also examined through Fourier transform infrared spectra. These showed clear carbonyl peak shifts due to the different types of hydrogen bonding. The PTAG-PU/PAN (30/70) blend had the maximum draw ratio at failure, measured in 100°C water; it was over 2.5 times that of pure PAN.     

Investigation on Changes in the Miscibility,Morphology, Rheology and Mechanical Behavior of Melt Processed Cellulose Acetate through Adding Polyethylene Glycol as a Plasticizer

Polyethylene glycol (PEG 200) was used as an eco-friendly plasticizer for preparing thermoplastic cellulose acetate (CA) by a twin-screw extruder. The plasticization efficiency of PEG 200 was compared with that of triethyl citrate (TEC). The interaction between polyethylene glycol and CA was investigated by Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Both FT-IR and DSC proved that PEG 200 could form stable and strong hydrogen bonds with CA molecules. Scanning electron microscopy (SEM) revealed that the CA granules were completely disrupted during the extrusion and a continuous and homogeneous phase was observed. The PEG 200-plasticized cellulose acetate (PCA) showed greater viscosity reduction than TEC-plasticized cellulose acetate (TCA) at the same additive levels. Furthermore, the Izod-notched impact strength and elongation at break of PCA were higher than those of TCA. The tensile strength, Izod-notched impact strength and elongation at break of PCA containing 25 wt% PEG 200 reached 31.6 MPa, 20.9 KJ/m² and 80.5%, respectively, as compared to 39.2 MPa, 10.9 KJ/m² and 32.3% for 25 wt% TEC plasticized CA.     

Preparation,Morphology and Properties of Poly(Trimethylene Terephthalate)/Thermoplastic Polyester Elastomer Blends

Poly(trimethylene terephthalate)(PTT)/thermoplastic polyester elastomer (TPEE) blends were prepared and their miscibility, crystallization and melting behaviors, phase morphology, dynamic mechanical behavior, rheology behavior, spherulites morphology, and mechanical properties were investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), parallel-plate rotational rheometry, polarized optical microscopy (POM), wide angle X-ray diffraction (WAXD), universal tensile tester and impact tester, respectively. The results suggested that PTT and TPEE were partially miscible in the amorphous state, the TPEE rich phase was dispersed uniformly in the solid matrix with a size smaller than 2 μm, and the glass transition temperatures of the blends decreased with increasing TPEE content. The TPEE component had a good effect on toughening the PTT without depressing the tensile strength. The blends had improved melt viscosities for processing. When the blends crystallized from the melt state, the onset crystallization temperature decreased, but they had a faster crystallization rate at low temperatures. All the blends’ melts exhibited a predominantly viscous behavior rather than an elastic behavior, but the melt elasticity increased with increasing TPEE content. When the blends crystallized from the melt, the PTT component could form spherulites but their morphology was imperfect with a small size. The blends had larger storage moduli at low temperatures than that of pure PTT.     

Morphology,Rheology, and Mechanical Properties of Polylactide/Poly(Ethylene-co-octene) Blends

Polylactide (PLA)/poly(ethylene-co-octene) (POE) blends containing ethylene-glycidyl methacrylate copolymer (EGMA) as a compatibilizer were prepared by melt blending. An immiscible, two-phase structure with POE dispersed in the PLA matrix was observed by scanning electron microscopy. It was found that the POE particle size was significantly decreased by the addition of EGMA, and the POE particle size and distribution decreased with the increase of the compatibilizer content up to 2% EGMA, beyond which the POE particle size and distribution remained unchanged. The reactions between the epoxy groups of EGMA and carboxylic or hydroxyl groups of PLA were elucidated by the Fourier transform infrared spectroscopy. Rheological results showed that the G′(ω), G″(ω), and complex viscosity of PLA/POE blends significantly increased at low frequencies with the addition of EGMA. The failure mode changed from brittle fracture of the neat PLA to ductile fracture of the PLA/POE blends.     

Dynamically Vulcanized Cis-1,3-Butadiene Rubber/Ethylene-Vinyl Acetate Copolymer/High- Impact Polystyrene Blends Compatibilized by Styrene-Butadiene-Styrene Block Copolymer

Compatibilized Cis-1,3-butadiene rubber (BR)/ethylene-vinyl acetate copolymer (EVA)/high-impact polystyrene (HIPS) thermoplastic blend vulcanizates (TPVs) were prepared by dynamic vulcanization, with TPVs being compatibilized by styrene-butadiene-styrene (SBS) block copolymer. The effects of SBS compatibilizer on mechanical, dynamic mechanical, and morphological properties of TPVs were investigated systematically. Experimental results indicated that the dynamically vulcanized BR/HIPS blends did not show an elastomeric behavior when the BR/HIPS blend ratio ranged from 30:70 to 70:30. However, the dynamically vulcanized BR/EVA/HIPS blends compatibilized with SBS showed obvious elastomeric behavior; thus SBS had a good compatibilization effect on BR/EVA/HIPS TPVs. The fractured surface morphology of compatibilized BR/EVA/HIPS TPV was relatively smooth, the interface interaction was strong, and there was no obvious micro-phase separation. BR particles were dispersed evenly in the etched surfaces of BR/EVA/SBS/HIPS TPV. A rubber process analyzer revealed that the storage modulus decreased significantly with increasing strain and the incorporation of compatibilizer SBS in TPVs weakened the Payne effect; the loss modulus showed a pronounced peak and tanδ increased continuously with increasing strain.     

Polymer micro-environmental effects on the fluorescence characteristics of 5-aminoquinoline and 3-aminoquinoline

In this paper we report the spectral and decay behavior of two probes viz. 5-aminoquinoline (5AQ) and 3-aminoquinoline (3AQ) in three different polymeric systems viz. poly methyl methacrylate (PMMA), polyvinyl alcohol (PVA) and cellulose acetate (CA). Absorption spectra are nearly identical for all the polymers but the emission shows larger shift in case of CA as compared to PMMA and PVA. The behavior is explained on the basis of higher hydrogen bond donating ability in case of CA because of the presence of cellulosic hydrogens. Observed multiexponential decays are explained on the basis of free as well as hydrogen-bonded species and also trapping in various excited state geometries of the matrix.     

Tensile properties and interfacial interactions of bimodal hard/soft latex blends

In this work, the effect of composition, particle size and particle size ratio on the tensile properties of well-characterized hard/soft latex blends was investigated. Four blends of hard/soft latices, with varying particle sizes (either small or large), and volume fractions of 100/0, 80/20, 60/40, 50/50, 40/60, 20/80 and 0/100 were studied. The stress at break increased and the strain at break decreased as the amount of hard particles in the blend increased. A simple model, introduced by Pukanszky for filled polymers and polymer blends, proved to be a very useful tool for evaluating the tensile properties of the latex blends. Parameter B of the model could be related to the specific surface of the dispersed hard particles and the particle size ratio. Increasing the specific surface of the dispersed hard particles resulted in an increase in parameter B. The influence of particle size ratio on parameter B was shown to depend on the formation of aggregates.     

Polyurea-reinforced polyacrylonitrile

Polyacrylonitrile (PAN) fibers were reinforced with three different types of polyurea (PU), which were synthesized in the presence of PAN dissolved in dimethyl formamide (DMF) (referred to as an in situ blend). Solution viscosity increased with increasing PU content, with viscosity yield seen at high PU content and an extended Newtonian plateau at low PU content. The reinforcing effect was greater with linear PUs, among which PU prepared from toluene diisocyanate (TDI) and ethylene diamine (EDA) gave the greatest improvement.     

Effect of Maleated Styrene/Ethylene-co-Butylene/Styrene on the Dispersed Particles Size and Mechanical Properties of Polyamide 6/Poly(styrene-co-acrylonitrile)/Poly(styrene-b-(ethylene-co-butylene)-b-styrene) Ternary Blends

In this study, the effect of several parameters, including composition, order of mixing, viscosity, and interfacial tension, on the phase structure and size of dispersed particles of polyamide 6 (PA6)/poly(styrene-co-acrylonitrile) SAN/poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) ternary blends was investigated. Moreover, the effect of addition of different ratios of reactive SEBS (maleic anhydride grafted-SEBS) and non-reactive SEBS at a fixed order of mixing and composition of 70/15/15 (PA6/SAN/SEBS + SEBS-g-MAH) on the mechanical properties of ternary blends was examined. Scanning electron microscopy (SEM) micrographs showed that among the studied parameters, interfacial tension and viscosity of dispersed phases were the leading factors in the formation of morphology and size of dispersed droplets. Mechanical results revealed that in contrast to the expectation, formation of core/shell structure of PA6/SAN/SEBS ternary blends did not result in a significant increasing of impact strength. The highest impact strength was achieved when a 50/50 weight ratio of SEBS/SEBS-g-MAH was used.     

Molecular mechanism of gelation upon the addition of water to a solution of poly(acrylonitrile) in dimethylsulfoxide

The solidification of a solution of poly(acrylonitrile) (PAN) in dimethylsulfoxide (DMSO) upon introduction of water into the solution is studied by Raman spectroscopy. In the absence of water, DMSO molecules are found to produce dipole-dipole bonds with PAN molecules. Upon the introduction of water, DMSO molecules produce hydrogen bonds with it and bands at 1005 and 1015 cm⁻¹ appear in the Raman spectrum, which are assigned to the valence vibrations of S=O bonds involved in the hydrogen bonds. Simultaneously, water molecules produce hydrogen bonds with PAN molecules: R-C≡N...H-O-H...N≡C-R, where R is the carbon skeleton of a PAN molecule. Accordingly, a band at 2250 cm⁻¹ arises in the Raman spectrum, which is assigned to the valence vibrations of C≡N bonds producing hydrogen bonds with a water molecule. When the water content is low and the DMSO concentration is high, the length of the hydrogen bonds varies in wide limits and the band at 2250 cm⁻¹ is wide. As the water content rises, DMSO molecules come out of PAN, the variation of the hydrogen bond length in it decreases (the band at 2250 cm⁻¹ narrows), and a high-viscosity system (gel) arises that consists of PAN molecules bonded to water molecules via “equally strong” hydrogen bonds.     

Phase Morphology and Dynamic Mechanical Properties of Nylon 6 Based Blends Prepared via Successive In Situ Ring Opening Polymerization

Acrylonitrile butadiene styrene (ABS)/nylon 6 blends were prepared via in-situ polymerization and a compatibilization method with various blend compositions. The monomer of nylon 6 (?-caprolactam) was polymerized using activated anionic ring opening polymerization in the presence of ABS. Hexamethylene diisocyanate (HDI) and styrene maleic anhydride (SMA) were used as microactivator and macroactivator at different concentrations. Phase morphology and dynamic mechanical properties were evaluated; and the blending method was compared with ordinary reactive extruding (melt blending). In samples with dispersed structure, the dispersed particle size decreased with increasing SMA. Also, the effects of SMA at lower levels of HDI were more significant, probably due to competition between the activators in the reaction. In some of the in-situ prepared blends, even in the co-continuous structure, particles with sizes under 500 nm were observed. A noteworthy observation in micrographs was that the sizes of the dispersed particle prepared by the in situ method were less than those prepared by the compounding method. Even the uncompatibilized in situ samples had a finer particle size in comparison with the ordinary compatibilized samples. The phase inversion point was also investigated; it was affected by both micro and macro activator concentrations. At higher HDI or SMA content, a lower phase inversion concentration (φ_Nylon6) was observed. In samples with an ABS dispersed phase, after in situ compatibilization using SMA, extraction of the ABS phase did not happen easily in the given time because of the surrounding copolymer at the particles surfaces. These blends had ultra-small particles (under 200 nm). Comparison of changes in the Tg_ABS and Tg_Nylon6 showed another interesting result. While the Tgs of samples prepared by the compounding method shifted about 3°C, the Tgs of samples prepared by the in situ method shifted more obviously (around 4–30°C). This indicated the powerful compatibilization caused by the in situ polymerization and compatibilization method. All results confirmed that the in situ polymerization and compatibilization method should be considered to be useful for production of ABS/nylon 6 blends.     

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.     

Tuning the hydrophobicity of ZSM-5 zeolites by surface silanization using alkyltrichlorosilane

ZSM-5 zeolites were modified with alkyltrichlorosilanes of various chain lengths (octyltrichlorosilane, decyltrichlorosilane, dodecyltrichlorosilane and hexadecyltrichlorosilane) and characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Thermal gravimetric analysis (TGA) and contact angle measurements (CA). The results showed that a closely packed and hydrophobic layer was presented at the particles surface and the surface wetting property varied from hydrophilic to hydrophobic, even to superhydrophobic. It was interesting to notice that the hydrophobic properties of modified ZSM-5 particles could be tuned by varying the chain length of chlorosilane and changing the pretreatment temperature before silanization. With increasing the alkyl chain length of trichlorosilane, the hydrophobicity increased. However, with an increase in the pretreatment temperature, the hydrophobicity decreased. Moreover, the relationship between the wetting properties and thermal stability was also investigated, the results showed that the modified ZSM-5 particles possessed good hydrophobicity at a temperature below 250 °C in air. These modified ZSM-5 particles may be utilized for many potential applications, such as membrane fillers, selective adsorbents, catalysts, chromatographic supports and so on.     

Dynamically Vulcanized Styrene-Butadiene Rubber/Ethylene-Vinyl Acetate Copolymer/High Impact Polystyrene Blends Compatibilized by Styrene-Butadiene-Styrene Block Copolymer

Thermoplastic vulcanizates (TPVs) based on styrene-butadiene rubber (SBR)/ethylene-vinyl acetate copolymer (EVA)/high-impact polystyrene (HIPS) blends were prepared by dynamic vulcanization, and the TPVs was compatibilized by styrene-butadiene-styrene block copolymer (SBS). The effects of SBS compatibilizer on mechanical, dynamic mechanical, and morphological properties of the TPVs were investigated systemically. Experimental results indicate that SBS had a good compatibilization effect on the SBR/EVA/HIPS TPVs. The tensile strength went through a maximum value at a compatibilizer resin content of 6 phr, and the elongation at break and tear strength increased with increasing SBS content. Morphology study shows that the vulcanized SBR particles were dispersed in the HIPS matrices. A rubber process analyzer reveals that the elastic modulus increased with increasing frequency and the incorporation of EVA in the TPVs led to the obvious decrease of elastic modulus; however, the further addition of compatibilizer SBS affected the elastic modulus less. The tan δ decreased continuously with increasing frequency. The addition of SBS in the TPVs led to enhanced hysteresis behavior and relatively high tan δ.     

Morphology and Mechanical Properties of Acrylonitrile-Butadiene-Styrene (ABS)/Polyamide 6 (PA6) Nanocomposites Prepared via Melt Mixing

Acrylonitrile-butadiene-styrene (ABS)/polyamide 6 (PA6) blends containing various amounts of organomontmorillonite (OMMT) were prepared using a twin-screw extruder followed by injection molding. The effect of OMMT on the microstructure and properties of the ternary nanocomposites is investigated by wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and mechanical properties testing. The results showed the OMMT platelets were preferentially located and exfoliated in the PA6 phase, but some were located at the interface of the ABS and PA6 phase. The effect of the addition of the OMMT on the morphology and mechanical properties was also evaluated. SEM revealed that the dimensions of the dispersed PA6 droplets were greatly reduced when the concentration of the OMMT was less than 4 phr. The domain size was less than the neat ABS/PA6 blends with the increasing of the OMMT content. It was suggested that the OMMT can compatibilize the ABS/PA6 blend. In addition, the flexural strength and modulus increased with increasing OMMT content, but the tensile strength became maximal at 3 phr OMMT. The OMMT had a negligible effect on the impact strength of the ABS/PA6 blend nanocomposite.     

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.     

Diamine-linked array of metal (Au,Ag) nanoparticles on glass substrates for reliable surface-enhanced Raman scattering (SERS) measurements

Metal (Au, Ag) nanoparticles (M NPs) (ca. 30–40 nm) prepared by citrate reduction method were arrayed on amine-terminated glass substrates using diamine linkers with different chain lengths. 1,4-diaminobutane (C-4 diamine) produced the uniform and densely-packed array of M NPs on glass substrates at appropriate concentration ranges, whereas diamine linkers with longer chain lengths (C-8 and C-12 diamines) produced more heterogeneous and aggregated array of M NPs. When compared to Ag NPs, Au NPs demonstrated more controllable and higher packing density due to their mono-dispersed size and higher affinity to diamine linkers. Uniformly arrayed M NPs (Au, Ag) on glass substrates exhibited high enhancement factors in SERS measurements of o-chlorothiophenol probes. Au NPs arrayed substrates exhibited an approximate power-law linearity of Raman intensity with probe concentrations (from 10⁻⁷ M to 10⁻⁴ M), demonstrating more reliable SERS substrates than Ag arrayed substrates with higher SERS activity.     

THERMAL CHARACTERIZATIONS OF WOOD FLOUR/STARCH CELLULOSE ACETATE COMPOUNDS

Thermogravity analysis (TGA) and differential scanning calorimetric (DSC) analysis, as well as dynamic thermal analysis (DMA), were carried out to study the interfacial interaction between wood flour (WF) and starch/cellulose acetate (SCA) blend. It was found that the main components in the compounds, namely, starch, cellulose, and cellulose acetate, started to decompose at around 330°C, a characteristic temperature for breaking glycoside-linked glucose units. Complexation of lignin in WF with amylose in SCA occurred during compounding, which gave rise to new crystallites that have a melting point of around 160°C. Hydrogen bonding is believed to play a key role in the crystallization. With increasing WF content, both the glass transition temperature and softening temperature increase as a result of the restricted molecular chain mobility imposed by rigid cellulose filaments. In addition, the DMA data revealed that amylose can occur as linkages in the crystallites. All these observations indicated that the interfacial adhesion between SCA and WF is relatively strong, even in absence of a coupling agent.