Highly compatible wood thermoplastic composites from lignocellulosic material modified in ionic liquids: Preparation and thermal properties

A study of converting chemically modified wood into thermoplastic materials was undertaken to develop a new technology platform for the effective utilization of wood‐based lignocellulosic materials. Highly substituted benzoylated spruce thermomechanical pulp (TMP) and lauroylated spruce TMP were used as components for thermoplastic composites of poly(styrene) and poly(propylene). Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) were used to characterize the interfacial morphology and thermal properties of the resultant composite filaments. The coupling of the interfacial morphology effort and that of torque analysis applied during processing indicated that the thorough modification of wood fibers by benzoylation and/or lauroylation reactions can improve the compatibility between the wood‐based lignocellulosic materials and poly(styrene) and poly(propylene). Thermal analysis showed that, with the addition of wood derivatives into poly(styrene) and poly(propylene) matrices, a slight decrease in their T_gs was observed. Furthermore, all of the prepared composites showed improved thermal stability, as revealed by TGA. The resultant thermoplastic wood composites exhibited good melting properties and were readily extruded into filaments or sheets. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Morphology of latex particles formed by poly(methyl methacrylate)-seeded emulsion polymerization of styrene

Poly(methyl methacrylate)–polystyrene composite particle latexes were prepared by poly(methyl methacrylate)-seeded emulsion polymerization of styrene employing batch, swelling-batch, and semibatch methods. The changes in particle morphology taking place during the polymerization reaction were followed by electron microscopy. Anchoring effect exerted by ionic terminal groups introduced by ionic initiator was found to be the main factor in controlling the particle morphology. The polymer particles obtained by oil-soluble hydrophobic initiators such as azobisisobutyronitrile and 4,4′-azobis-(4-cyanovaleric acid) gave the inverted core-shell morphology. Water-soluble hydrophilic initiator, K₂S₂O₈, also gave the inverted core-shell morphology. However, in this case the occurrence of the halfmoonlike, the sandwichlike, and the core-shell morphologies were also observed depending upon the polymerization conditions. The distribution of terminal ? SO groups on the surface area of polystyrene particles could be controlled by initiator concentration and polymerization temperature. Viscosity of polymerization loci dictated the movement of polymer molecules, thus causing the unevenness of particle shape and phase separation at high viscosity state. Viscosity was controlled by the styrene/poly(methyl methacrylate) ratio, the addition of a chain transfer agent or a solvent which is common to polystyrene and poly(methyl methacrylate).     

Radical copolymerization of sulphur dioxide and styrene: 4. Intramolecular excimer formation in poly(styrene sulphone)s

Intramolecular excimer formation in poly(styrene sulphone)s with various compositions has been investigated based on the characteristic monomer sequence distributions which were determined experimentally. The fluorescence spectra of the poly(styrene sulphone)s show two emission bands at 285 nm and 330 nm as for polystyrene, corresponding to the monomer and the excimer bands, respectively. The ratio of the excimer to the monomer emission intensities (I_e/I_m) is linearly correlated with the mole fraction of styrene. This observation is a consequence of the characteristic sequence distributions in poly(styrene sulphone)s. containing a very small fraction of SMS units (S = SO₂; M = styrene). The efficiency of excimer formation in poly(styrene sulphone)s with regular styrene sequences, e.g. dyad sequence only, was calculated from the sequence distribution and empirical I_e/I_m. It is concluded that the excimer formation in poly(styrene sulphone)s is very efficient. Energy migration along the copolymer chain was also demonstrated by measuring the degree of polarization as a function of copolymer composition. The efficient excimer formation and the depolarization in poly(styrene sulphone)s suggest that the SO₂ unit in poly(styrene sulphone)s does not act as a barrier or trap to energy migration unlike the methyl methacrylate unit.     

Synthesis and characterization of novel type poly (4-chloromethyl styrene-grft-4-vinylpyridine)/TiO2 nanocomposite via nitroxide-mediated radical polymerization

This paper describes the synthesis and characterization of novel type poly (4-chloromethyl styrene-graft-4-vinylpyridine)/TiO₂ nanocomposite. Firstly, poly (4-chloromethyl styrene)/TiO₂ nanocomposite was synthesized by in situ free radical polymerizing of 4-chloromethyl styrene monomers in the presence of 3-(trimethoxysilyl) propylmethacrylate (MPS) modified nano-TiO₂. Thereafter, 1-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO-OH) was synthesized by the reduction of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). This functional nitroxyl compound was covalently attached to the poly (4-chloromethyl styrene)/TiO₂ with replacement of chlorine atoms in the poly (4-chloromethyl styrene) chains. The controlled graft copolymerization of 4-vinylpyridine was initiated by poly (4-chloromethyl styrene)/TiO₂ nanocomposite carrying TEMPO groups as a macroinitiators. The coupling of TEMPO with poly (4-chloromethyl styrene)/TiO₂ was verified using ¹H nuclear magnetic resonance (NMR) spectroscopy. The obtained nanocomposites were studied using transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and the optical properties of the nanocomposites were studied using ultraviolet-visible (UV-Vis) spectroscopy.     

Copolymerization of aniline and styrene using various surfactants in aqueous media

Polyaniline/polystyrene (PAn/PS) copolymer was prepared in the aqueous solution by copolymerization of styrene and aniline using potassium iodate (KIO₃) and ammonium persulfate ((NH₄)₂S₂O₈) as an oxidant in the presence of various surfactants such as poly(ethylene glycol), hydroxypropylcellulose, and surfactive dopant sodium dodecylbenzenesulfonate. The PAn/PS copolymer was characterized in terms of conductivity, morphology, chemical structure, and glass transition temperature. The results indicate that the morphology, conductivity, and glass transition temperature of products are dependent on the type of surfactant. Furthermore, it was found that addition of styrene monomer into stirred aqueous solution influences the surface morphology. The chemical structure and glass transition temperature of product were studied by Fourier transform infrared spectroscopy and differential scanning calorimetry respectively. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Pyrolysis–molecular weight chromatography–vapor-phase infrared spectrophotometry: An on-line system for analysis of polymers. III. Thermal decomposition of polysulfones and polystyrene

The thermal decomposition of poly(butene-1 sulfone), poly(pentene-1 sulfone), poly(hexene-1 sulfone), poly(styrene sulfone), and polystyrene was investigated in helium at a heating rate of 20°C/min using an experimental system which consists of a programmable pyrolyzer, a thermal conductivity detector, a mass chromatograph, and a vapor-phase infrared spectrophotometer. Poly(butene-1 sulfone), poly(penetene-1 sulfone), and poly(hexene-1 sulfone) displayed two-step decomposition; the primary products of decomposition at both steps were the comonomers (olefin and SO₂). For poly(styrene sulfone), in addition to styrene and SO₂, products with molecular weights corresponding to dimers of styrene were observed. Decomposition of this polymer was compared with that of polystyrene, which formed mostly monomer.     

Effect of block composition on the morphology and transport properties of sulfonated fluoroblock copolymer blend membranes

This study focuses on the relationship between the transport properties and the morphological changes of ionic block copolymer blend membranes, as a function of the fluoroblock chemical composition and loading. Poly(styrene‐b‐isobutylene‐b‐styrene) was sulfonated and blended with three different fluoropolymers: Poly(styrene)‐b‐poly(2,3,4,5,6‐pentafluorostyrene)‐b‐poly(2,2,3,4,4,4‐hexafluorobutyl methacrylate) [PS‐b‐PFS‐b‐PHFBMA], a difluoroblock copolymer composed of PS‐b‐PHFBMA and a homopolymer composed of PHFBMA. Equilibrium and transport properties (e.g., ion exchange capacity, water uptake, water content, proton conductivity, and methanol permeability), were shown to be significantly influenced by the chemical nature of the fluoroblock copolymer, the fluoropolymer content, and their resulting morphology. Proton conductivity and methanol permeability were very sensitive to the incorporation of PHFBMA. Polymer blends composed of sulfonated poly(styrene‐b‐isobutylene‐b‐styrene) (SIBS SO₃H) and PHFBMA above 9 wt% showed interconnected ionic domains that have a shorter correlation length and high water content, which results in improved transport properties for direct methanol fuel cell (DMFC) applications. POLYM. ENG. SCI., 57:1262–1272, 2017. © 2017 Society of Plastics Engineers     

On the thermal degradation of poly(styrene sulfones). VII. Evaluations of poly(styrene sulfone) thermal stability using invariant kinetic parameters

The thermal degradation behavior of poly(styrene sulfone) was investigated by thermogravimetric analysis (TGA) measurement. This study described its thermal stability by applying the invariant kinetic parameter (IKP) method. The thermogravimetric and differential thermogravimetric analyses of different compositions of poly(styrene sulfones) were carried out over the temperature range 100–500°C under nitrogen. The kinetic parameters (preexponential factor and activation energy) of thermal decomposition of poly(styrene sulfone) can be obtained by dynamic measurement of TGA. The IKP method assumes that the kinetic parameters are independent of the experimental conditions. These parameters are computed without any hypothesis on the form of the kinetic degradation function. Invariant activation energies of the degradation of poly(styrene sulfone) show that the thermal stability decreases as the SO₂ content of poly(styrene sulfone) increases due to the thermal instability of the C? S bond. The relation equation, Ea_inv = 237.0 ? 290.5X_SO2, where X_SO2 is the molecular fraction of SO₂, was obtained to describe the effect of sulfur dioxide on the thermal stability of poly(styrene sulfone). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1698–1705, 2002     

Toughening and Compatibilization of Acrylonitrile–Butadiene–Styrene/Poly (Ethylene Terephthalate) Blends Using an Oxazoline-Functionalized Impact Modifier

An oxazoline-functionalized core–shell impact modifier was synthesized between aminoethanol and acrylonitrile/butadiene/styrene high rubber powder. According to the Fourier transform infrared spectroscopy test, the nitrile groups were partially converted into oxazoline groups successfully. The oxazoline-functionalized acrylonitrile/butadiene/styrene high rubber powder was used as an impact modifier for acrylonitrile–butadiene–styrene/poly(ethylene terephthalate) blends. The differential scanning calorimeter and rheological tests demonstrated that poly(ethylene terephthalate) was partially miscible with acrylonitrile–butadiene–styrene, because the oxazoline groups of oxazoline-functionalized acrylonitrile/butadiene/styrene high rubber powder reacted with the end groups of poly(ethylene terephthalate). The results of scanning electron microscopy indicated that the morphology of acrylonitrile–butadiene–styrene/poly(ethylene terephthalate) blends with proper oxazoline-functionalized acrylonitrile/butadiene/styrene high rubber powder content was improved significantly. The best mechanical properties were achieved, When 6 wt% oxazoline-functionalized acrylonitrile/butadiene/styrene high rubber powder was added into acrylonitrile–butadiene–styrene/poly(ethylene terephthalate) blends.     

Compatibilization effects of styrenic/rubber block copolymers in polypropylene/polystyrene blends

Compatibilizing effects of styrene/rubber block copolymers poly(styrene‐b‐butadiene‐b‐styrene) (SBS), poly(styrene‐b‐ethylene‐co‐propylene) (SEP), and two types of poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS), which differ in their molecular weights on morphology and selected mechanical properties of immiscible polypropylene/polystyrene (PP/PS) 70/30 blend were investigated. Three different concentrations of styrene/rubber block copolymers were used (2.5, 5, and 10 wt %). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the phase morphology of blends. The SEM analysis revealed that the size of the dispersed particles decreases as the content of the compatibilizer increases. Reduction of the dispersed particles sizes of blends compatibilized with SEP, SBS, and low‐molecular weight SEBS agrees well with the theoretical predictions based on interaction energy densities determined by the binary interaction model of Paul and Barlow. The SEM analysis confirmed improved interfacial adhesion between matrix and dispersed phase. The TEM micrographs showed that SBS, SEP, and low‐molecular weight SEBS enveloped and joined pure PS particles into complex dispersed aggregates. Bimodal particle size distribution was observed in the case of SEP and low‐molecular weight SEBS addition. Notched impact strength (a_k), elongation at yield (ε_y), and Young's modulus (E) were measured as a function of weight percent of different types of styrene/rubber block copolymers. The a_k and ε_y were improved whereas E gradually decreased with increasing amount of the compatibilizer. The a_k was improved significantly by the addition of SEP. It was found that the compatibilizing efficiency of block copolymer used is strongly dependent on the chemical structure of rubber block, molecular weight of block copolymer molecule, and its concentration. The SEP diblock copolymer proved to be a superior compatibilizer over SBS and SEBS triblock copolymers. Low‐molecular weight SEBS appeared to be a more efficient compatibilizer in PP/PS blend than high‐molecular weight SEBS. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 291–307, 1999     

Phase rearrangement in two-stage emulsion polymers of butyl acrylate and styrene: Mechanical properties

The mechanical and thermal properties of films from a series of two-stage emulsion polymers were investigated. The emulsion polymers were made by polymerizng styrene in the presence of a preformed poly(butyl acrylate-co-divinyl benzene) seed latex. The effects of seed particle size, seed particle crosslinking via the amount of divinyl benzene, styrene/butyl acrylate ratio, and thermal history on the film properties were studied. Latex particles were characterized by light scattering and film formation behavior. Dried films were characterized by differential scanning calorimetry, dynamic mechanical analysis, and stress-strain behavior. Although evidence was obtained for nearly complete phase separation between the polystyrene (PS) and poly(butyl acrylate) (PBA) phases, the site of styrene polymerization and thus the PS phase morphology is influenced by seed particle size, seed crosslinking, and S/BA ratio. The morphology of as-dried films consists of finely dispersed PS domains in a continuous PBA matrix. Thermal annealing above the PS T_g causes coalescence of the PS domains, resulting in significantly improved mechanical properties. The extent of PS phase coalescence is also influenced by the level of seed crosslinking.     

Microencapsulation of disperse dye particles with nano film coating through layer by layer technique

Throughout the past ten years, comprehensive understanding of fundamental and applied research has focused on functional coating and specifically on microencapsulaion. In this study, weak polycation poly(allylamine hydrochloride) and strong polyanion poly(sodium styrene sulfonate) were used for fabrication of nano film through layer by layer technique on the surface of disperse dye particles. Then micron‐sized particles were surrounded by poly(urea formaldehyde) using in‐situ polymerization. Chemical structure, surface morphology, and size distribution of these novel microcapsules were characterized by Fourier transform infrared spectrometry, differential scanning calorimetry, optical microscopy, and scanning electronic microscopy. Size and surface morphology of the microcapsules can be optimized by selecting proper weight ratio of urea to formaldehyde and core to shell material type, and amount of surfactant and agitation rate. This technology demonstrated good capability in several applications in textile industry, such as dying fabrics because of saving huge amount of water and showing slow‐release property of dye without using dye assistant agents. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and application of sulfonated poly(1‐octene‐co‐styrene)

In this article, 1‐octene and styrene was copolymerized by the supported catalyst (TiCl₄/ID/MgCl₂). Subsequently, by sulfonation reaction, sulfonated poly(1‐octene‐co‐styrene)s which were amphiphilic copolymers were prepared. The copolymerization behavior between 1‐octene and styrene is moderate ideal behavior. Copolymers prepared by this catalyst contain appreciable amounts of both 1‐octene and styrene. Increase in the feed ratio of styrene/1‐octene leads to increase in styrene content in copolymer and decrease in molecular weight. As the polymerization temperature increases, the styrene content in the copolymers increases, however, the molecular weight decreases. Hydrogen is an efficient regulator to lower the molecular weights of poly(1‐octene‐co‐styrene)s. The sulfonation degree of the sulfonated poly(1‐octene‐co‐styrene)s increased as the styrene content in copolymer increased or the molecular weight decreased. Thirty‐six hour is long enough for sulfonation reaction. The sulfonated poly(1‐octene‐co‐styrene)s can be used as effective and durable modifying agent to improve the wettability of polyethylene film and have potential application in emulsified fuels and for the stabilization of dispersions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Rheological behavior and morphology of blends of copolymers of α-methylstyrene-co-acrylate with PVC

The copolymers of poly(α-methyl styrene–methyl acrylate) (PMSMA) and poly(α-methyl styrene–ethyl acrylate) (PMSEA) were synthesized by emulsion polymerization. The compatibility of these copolymers with poly(vinyl chloride) (PVC) was estimated by the solubility parameter method and scanning electron microscopy (SEM). The rheological behavior was investigated by a flow tester. The mechanical properties, rheological behavior, and morphology of these blends show that these copolymers can be used as a processing aid for PVC. © 1996 John Wiley & Sons, Inc.     

Physical and mechanical properties of nanocomposite barrier film containing encapsulated nanoclay

Waterborne poly(styrene‐co‐butyl acrylate) was prepared via miniemulsion polymerization in which nanoclay (Cloisite® 30B, modified natural MMT) in different concentrations was encapsulated. Scanning electron microscopy, X‐ray diffraction, and transmission electron microscopy confirmed the encapsulation and intercalated‐exfoliated structure of Cloisite® 30B within poly(styrene‐co‐butyl acrylate). The effect of nanoclay content on water vapor permeability, water uptake, oxygen permeability, thermal, and mechanical properties of thin films containing 1.5, 2.56, 3.5, and 5.3 wt % encapsulated Cloisite® 30B in poly(styrene‐co‐butyl acrylate) was investigated. The presence of encapsulated Cloisite® 30B within the polymer matrix improved tensile strength, Young's modulus, and toughness of the nanocomposites depending on the nanoclay content. Water vapor transmission rate, oxygen barrier properties, and thermal stability were also improved. The results indicated that the incorporation of Cloisite® 30B in the form of encapsulated platelets improved physicomechanical properties of the nanoclay‐polymer composite barrier films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Dispersion copolymerization of acrylonitrile‐vinyl acetate in supercritical carbon dioxide

Dispersion copolymerization of acrylonitrile‐vinyl acetate (AN‐VAc) had been successfully performed in supercritical carbon dioxide (ScCO₂) with 2,2‐azobisisobutyronitrile (AIBN) as a initiator and a series of lipophilic/CO₂‐philic diblock copolymers, such as poly(styrene‐r‐acrylonitrile)‐b‐poly(1,1,2,2‐tetrahydroperfluorooctyl methacrylate) (PSAN‐b‐PFOMA), as steric stabilizers. In dispersion copolymerization, poly(acrylonitrile‐r‐vinyl acetate) (PAVAc) was emulsified in ScCO₂ effectively using PSAN‐b‐PFOMA as a stabilizer. Compared with the precipitation polymerization (absence of stabilizer), the products prepared by dispersion polymerization possessed of higher yield and higher molecular weight. In addition, the particle morphology of precipitation polymerization was irregular, but the particle morphology of dispersion polymerization was uniform spherical particles. In this study, the effects of the initial concentrations of monomer and the stabilizer and the initiator, and the reaction pressure on the yield and the molecular weight and the resulting size and particle morphology of the colloidal particles were investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5640–5648, 2006     

Phase Morphology,Thermal, Thermomechanical and Interfacial Properties of PP/SAN/SBS Blend Systems

The effect of styrene–butadiene–styrene content on morphology, melting, crystallinity, dynamic mechanical properties and relaxation processes of polypropylene/poly(styrene-co-acrylonitrile)/styrene–butadiene–styrene blends was investigated. Styrene–butadiene–styrene reduced the average size of dispersed particles and generated complex aggregates in the matrix. Morphology development examined by dynamic mechanical thermal analysis showed increased damping of poly(styrene-co-acrylonitrile) domains at high styrene–butadiene–styrene contents. All blends showed reduced crystallinity and melting point compared with neat polypropylene. Poorer nucleation effect of dispersed particles at high styrene–butadiene–styrene loadings was observed. Compatibilization accelerated the form relaxation of dispersed particles. Additional relaxation process probably due to styrene–butadiene–styrene chains was observed in blends containing 10% and higher styrene–butadiene–styrene content.     

Reactive blending of poly (dimethylsiloxane) with nylon 6 and poly (styrene):Effect of reactivity on morphology

Reactive compatibilization was used to control and stabilize 20–30wt% poly(dimethylsioxane) (PDMS) dispersions in nylon 6 (PA) and poly(styrene) (PS), respectively. The effect of the type of reation (amine (NH₂)/anhydride (An), NH₂/ epoxy(E) and carboxylic acid (COOH)/E) on the morphology was studied with electron microscopy. PS and PDMS have mutual solvents thus it was possible to use gel permeation chromatography (GPC) to determine the concentration of block copolymer in PS/PDMS blends. Reactive blending of PA6 with difunctional PDMS‐(AN)₂ did not decrease the PDMS particle size compared to the non‐reactive blend (～10μm). Particle size decreaeased significantly to about 0.5 μm when PA6 was blended with a PDMS containing about 4 random An groups along the chain. For the PS/PDMS blends, GPC revealed that the NH₂/An reaction formed about 3% block copolymer and produced stable PDMS particles ～ 0.4 μm. No reaction was detected for the PS‐NH₂/PDMS‐E blend and the morphology was coarse and unstable. Also, PS‐NH₂/PDMS‐An reactivity was lower compared to other systems such as PS/ poly (isoprene) and PS/poly(methaacrylte) using the same reaction. This was attributed to the relatively thinner PS/PDMS interface dueto the high PS/PDMs immiscibility.     

Dispersion polymerization of styrene in supercritical CO2 stabilized by random copolymers of 1H,1H-perfluorooctyl methacrylate and 2-dimethylaminoethyl methacrylate

The dispersion polymerizations of styrene in supercritical CO₂ employing random copolymers composed of 1,1-dihydroperfluorooctyl methacrylate (FOMA) and 2-dimethylaminoethyl methacrylate (DMAEMA) (poly(FOMA-co-DMAEMA)) as stabilizers were investigated with two different compositions. It was demonstrated that micron-sized, free-flowing, spherical polystyrene (PS) particles could be obtained in high yields by poly(FOMA-co-DMAEMA) containing as low as 50% (w/w) FOMA. Results indicate that DMAEMA units in the stabilizer, as an anchor group with its special characteristics, can be adsorbed on PS particles to provide an enough colloidal stability. The initial concentration of styrene and the stabilizer affected the molecular mass, polymerization yield, and the morphology of PS particles. The PS particles could be redispersed in buffered water (pH 2.1) by an ionic stabilization mechanism provided by DMAEMA units on the surface. Dynamic light scattering (DLS) measurements of aqueous latexes gave similar particle sizes as those from SEM analysis.     

Mechanical properties of SBS block copolymers. II. Effect of structure and selective solvent casting on stress–strain properties and mechanical hysteresis

Near-equilibrium stress–strain properties were obtained for poly(styrene–b–butadiene) copolymer films cast from different solvents at 35°C. The solvents used were methyl ethyl ketone and cyclohexane, selective for PS and PB, respectively, and toluene, a common solvent for both copolymer components. Tensile properties were studied at two successive loading cycles up to a maximum elongation ratio of λ_max = 7.0. At constant composition, the results were interpreted on the basis of the available morphology for these systems. The effect of hard block content (35% to 45% styrene) and at constant composition (39% styrene) of block length was also examined on such properties as elasticity and mechanical hysteresis. The results indicate that at constant composition the PB block length influences elasticity and mechanical hysteresis, also that films cast from a common solvent have higher tensile strength and increased mechanical hysteresis presumably because of a more effective load transfer between phases.