Thermoplastic elastomers from rubber and recycled polyethylene: chemical reactions at interphases for property enhancement

Recycled low density polyethylene (R‐LDPE) has been reactively compatibilized with butadiene rubber (BR) by using small additions of reactive polyethylene copolymers and reactive BRs to produce thermoplastic elastomers (TPEs). TPEs were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), rheology measurements, wide‐angle X‐ray scattering (WAXS) and mechanical testing. WAXS results show that the presence of BR and reactive modifiers does not completely prevent the crystallization of R‐LDPE during the TPE formation. Depression of the melting point has been found in all cases. Also in all cases, compatibility is provided by formation of interfacial layers. The best mechanical characteristics are obtained for R‐LDPE + BR blends compatibilized with poly(ethylene‐co‐acrylic acid) (PE‐co‐AA) and polybutadiene terminated with isocyanate groups (PB‐NCO) for PB‐NCO = 7.5 wt% per PB and COOH/NCO ratio = 1/1. The stress at break and elongation at break are respectively improved by 31 % and 63 %. The PB‐NCO modifier participates in co‐vulcanization with BR in the rubber phase and reacts at the interface with the PE‐co‐AA dissolved in the polyolefin phase. As a result, the amorphous phase of R‐LDPE is dissolved by the rubber phase and a morphology with dual phase continuity is formed, assuring an improvement of mechanical properties of TPEs. Copyright © 2004 Society of Chemical Industry     

Biodegradable composites: Morphological,chemical, thermal,and mechanical properties of composites of poly(hydroxybutyrate‐co‐hydroxyvalerate) with curaua fibers after exposure to simulated soil

Composites produced from biodegradable polymeric matrixes reinforced with vegetable fibers have attractive mechanical properties and are environmentally friendly. This work is directed to the biodegradation of a composite made of a poly(hydroxybutyrate‐co‐hydroxyvalerate) matrix reinforced with curaua fibers (with and without alkaline treatment) in simulated soil. The composites were developed by extrusion and injection and were later buried in simulated soil according to the ASTM G160‐03 method. Scanning electron microscopy showed evidence of microbial attack on the samples surfaces. Infrared spectra showed that the composites biodegradation was mainly caused by erosion of the surface layer resulting from microorganisms activity. Thermogravimetric analysis pointed out reduced thermal stability of the samples, and results of differential scanning calorimetry showed that the degree of crystallinity increases and then decreases progressively throughout the degradation period, indicating that enzymatic degradation primarily occurs in the amorphous phase material and thereafter in the crystalline phase. For curaua composite fibers, reductions in tensile strength and elastic modulus are more significant, indicating that the presence of fibers promotes biodegradation of the curaua fiber. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40712.     

抗菌剂在抗菌涂料中的应用研究

根据国外抗菌涂料的抗菌和防霉特性,研究了商业主要抗菌剂的抗菌性能,介绍了测试抗菌性能的两种方法:抑菌圈法和JIS?Z?2801。详细研究了基材、膜厚、浸滤、罐内防腐剂等可变因素对抗菌性能的影响。     

Metal ion sorption properties of water-insoluble resins based on sodium styrene sulfonate and different comonomers

A set of water-insoluble resins based on sodium styrene sulfonate and different comonomers were synthesized. The resins poly(mono-2-(methacryloyloxy)ethyl succinate-co-sodium 4-styrene sulfonate) P(MOES-co-SSNa), poly(2-acrylamido glycolic acid-co-sodium 4-styrene sulfonate) P(AGA-co-SSNa), poly(acrylamide-co-sodium 4-styrene sulfonate) P(AAm-co-SSNa), and poly(2-(dimethylamine)ethyl acrylate-co-sodium 4-styrene sulfonate) P(DMAEA-co-SSNa) were synthesized by solution radical polymerization. The metal ion retention properties were studied by batch procedure for Cd(II), Zn(II), Pb(II), and Hg(II). Resins performance was compared with a poly(sodium 4-styrene sulfonate) (PSSNa) resin in order to evaluate the effect of comonomer on sorption properties. The effect of pH, time, temperature, and maximum retention capacity were studied. In addition, sorption experiments were carried out under competitive ion conditions to study the selectivity of resins. The resins P(AAm-co-SSNa) and P(AGA-co-SSNa), showed the most important differences compared with PSSNa resin, the former present higher sorption and the latter presented selectivity for Hg(II) at pH 2.     

Effects of biocide treatments on durability of wood and bamboo/high density polyethylene composites against algal and fungal decay

The main objective of this study was to investigate the algal and fungal resistance of biocide‐treated wood flour (WF)/high density polyethylene (HDPE) and bamboo flour (BF)/HDPE composites. The biocides included 4,5‐dichloro‐2‐octyl‐isothiazolone (DCOIT), zinc pyrithione (ZPT), and carbendazim (MBC). Resistance to algae and fungi was evaluated by artificially accelerated tests. Treated and untreated samples were exposed to algae (Chlorella vulgaris, Ulothrix sp., Scenedesmus quadricauda, and Oscillatoria sp.) and fungi (Coriolus versicolor and Poria placenta) for 21 days and 12 weeks, respectively. The volatile components of WF and BF extractives were analyzed by gas chromatography‐mass spectrometry (GC‐MS). The results indicated that incorporation of DCOIT, ZPT, and MBC effectively enhanced the durability of WF/HDPE and BF/HDPE composites against algal and fungal decay. Accordingly, DCOIT, ZPT, and MBC can be used as potential biocides for both WF/HDPE and BF/HDPE composites. GC‐MS analysis suggested that palmitic acid, oleic acid, stigmasta‐3,5‐dien‐7‐one, and vanillin in WF possibly provided some resistance to fungal attack, whereas di (2‐ethylhexyl) phthalate and linoleic acid in BF were responsible for algal resistance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45148.     

Continuous production of poly(3-hydroxybutyrate-<Emphasis Type="Italic">co</Emphasis>-3-hydroxyvalerate): Effects of C/N ratio and dilution rate on HB/HV ratio

Ralstonia eutropha was cultivated in a continuous stirred fermenter with various C/N ratios (20, 30, and 40), dilution rates, and organic salt substrates (sodium propionate or sodium valerate) to explore the microbial growth and the poly(3HB-co-3HV) accumulation. When sodium propionate was used as the secondary carbon source, the HB/HV molar ratio at various C/N ratios and dilution rates did not change appreciably (approximately 90: 10). The highest poly(3HB-co-3HV) content in biomass (41.8%) and poly(3HB-co-3HV) productivity (0.100 g/(L·h)) occurred under the condition with a C/N ratio of 20 and dilution rate of 0.06 h⁻¹. When sodium valerate was used as the secondary carbon source, the productivity of poly(3HB-co-3HV) increased with increasing dilution rate for the C/N ratio of 30 and 40. The average HB/HV molar ratio ranged from 48: 52 to 78: 32. The feeding of sodium valerate promoted the accumulation of HV better than feeding sodium propionate did. This study shows that a potential strategy of manipulating by both C/N ratio and dilution rate could be used to control the HV unit fraction in poly(3HB-co-3HV) in a continuous cultivation.     

Comparative deformational characteristics of poly(styrene-b-ethylene-co-butylene-b-styrene) thermoplastic elastomers and cross-linked natural rubber

Three poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) thermoplastic elastomers (TPEs) are studied mechanically and compared to cross-linked natural rubber. It is observed that subtle alterations in the mid-block of the TPEs affect their mechanical properties significantly. The stress relaxation at room temperature is significantly altered indicating a reduced flow in systems where the ratio of ethylene to butylene segments in the mid-block is greater than one. The cyclic behavior of these systems also shows significant hysteresis. Differential scanning calorimetry suggests that these TPEs crystallize at low temperatures, similar to the observed behavior in cross-linked natural rubber. Results of internal energy changes from deformation calorimetry provide evidence for strain-induced crystallization occurring in certain SEBS systems, similar to the internal energy changes observed for cross-linked natural rubber. Simultaneous WAXD/SAXD measurements on deformed SEBS samples highlight deformation at the nanometer and the molecular length scales. In situ WAXD at different strains further reinforces the evidence for formation of strain-induced crystallites in the selected systems. Strain-induced crystallization occurring in certain TPEs provides a mechanism for reduction of flow at high strains and accounts for the retention of their highly elastic behavior.     

Dynamic Melt Rheological Properties of Ionomers Based on Poly(Ethylene-co-Acrylic Acid) and Poly(Ethylene-co-Methacrylic Acid)

The high temperature stability, and the dynamic melt rheological properties of poly(ethylene-co-acrylic acid) (EAA), zinc salt of EAA, and sodium salt of EAA were evaluated in the molten state over broad ranges of shear rates and temperatures using ARES (Rheometrics). The master curves of G′ and G″ as a function of angular frequency (ω) were constructed for each material. The influence of ionic groups on the storage modulus (G′), loss modulus (G″), complex viscosity (η*), and flow activation energy (E_a) were analyzed. The results of EAA based ionomers are discussed with those of the ionomers based on poly(ethylene-co-methacrylic acid) (EMAA). The linear visco-elastic spectra, and flow activation energies of the two series of ionomers show differences.     

Miscibility studies of polymer blends by viscometry methods

The intrinsic viscosities of blends of poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) (PVC/EVA), poly(vinyl chloride)/poly(styrene-co-acrylonitrile) (PVC/SAN), and poly(ethylene-co-vinyl acetate)/poly(styrene-co-acrylonitrile) (EVA/SAN) have been studied in cyclohexanone as a function of blend composition. In order to predict the compatibility of polymer pairs in solution, the interaction parameter term, Δb, obtained from the modified Krigbaum and Wall theory, and the difference in the intrinsic viscosities of the polymer mixtures and the weight average intrinsic viscosities of the two polymer solutions taken separately are used. © 1994 John Wiley & Sons, Inc.     

Antimicrobial activity of organic photosensitizers embedded in electrospun nylon 6 nanofibers

Nylon 6 nanofibers containing organic photosensitizers were investigated to demonstrate the antimicrobial properties in the application of the material to protective clothing and home appliances. Benzophenone (BP), 4, 4′‐bis(dimethylamino)benzophenone (MK) and thioxanthen‐9‐one (TX) were used as photosensitizers and the nylon 6 nanofibers were prepared using electrospinning. Field emission scanning electron microscopy morphology of the nanofibers showed that even and continuous nylon 6 nanofibers were well prepared through electrospinning and that the organic photosensitizers were evenly distributed in the nanofibers. There was no significant reduction of crystallinity in the nylon 6 nanofibers through the insertion of the organic photosensitizers. After UV (365 nm) irradiation of the photosensitizers, the intensity of peak photon excitation in the electron spin resonance spectra was increased. Antimicrobial properties of the prepared nanofibers were tested against Staphylococcus aureus and Escherichia coli according to JIS Z 2801. It was found that antimicrobial properties of nylon 6 nanofibers containing MK and TX were superior to those of nylon 6 nanofibers containing conventionally used BP. The antimicrobial effects of the nanofibers for S. aureus were superior to those for E. coli. The antimicrobial activity gradually increased as the UV irradiation time increased. Copyright © 2012 Society of Chemical Industry     

Synthesis of an acrylate elastomer with UV stabilization and its application in polyoxymethylene

In this study, an acrylate elastomer with light‐stable functional groups was synthesized by methyl methacrylate (MMA), butyl acrylate (BA), and a polymerizable UV stabilizer 2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylproroxy) benzophenone (BPMA) via emulsion polymerization, and the product was poly[methyl methacrylate‐co‐butyl acrylate‐co‐2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylproroxy) benzophenone] [poly(MMA‐co‐BA‐co‐BPMA)]. The composition and characteristics of poly (MMA‐co‐BA‐co‐BPMA) were determined by using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H‐NMR), and ultraviolet–visible absorption spectroscopy (UV–vis). Further, the obtained poly(MMA‐co‐BA‐co‐BPMA) was blended with polyoxymethylene (POM) to modify its photostabilization, as well as the mechanical properties of POM composite were tested before and after UV irradiation. The result showed that poly(MMA‐co‐BA‐co‐BPMA) can be dispersed well in the POM matrix, which could play a role of improving compatibility with and toughening for POM, and its light‐stable functional groups could increase the UV resistance of POM composite. Mechanical properties of modified POM were kept well with higher impact strength and elongation at break than pure POM after UV irradiation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Blending Modification of PHBV/PBS/PEG and its Biodegradation

This study used poly(butylene succinate) and poly(ethylene glycol) to modify poly(3-hydroxybutyrate-co-3-hydroxyvalerate). The results showed that the incorporation of poly(butylene succinate) and poly(ethylene glycol) improved the mechanical properties of blends. The results showed that crystallinity of the poly(ethylene glycol)-containing blends decreased, so do the crystallization temperature and melting temperature of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) component of blends. Poly(butylene succinate)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(ethylene glycol) ratio of 50:20:30 was chosen owing to its good properties. The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) component of blends can be degraded completely by Pseudomonas mendocina DS04-T, whereas this strain cannot degrade poly(butylene succinate) and poly(ethylene glycol). Apart from poly(butylene succinate), Fusarium sp. FS1301 can also biodegrade poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(ethylene glycol).     

Synthesis and characterization of acrylamide‐based aluminum flocculant for turbidity reduction in wastewater

Polymeric flocculants of aluminum hydroxide‐poly[acrylamide‐co‐(acrylic acid)], AHAMAA, were prepared by solution polymerization using aluminum hydroxide as a coagulant in the presence of acrylamide (AM) and acrylic acid (AA) as a comonomer pair with N,N′‐methylenebisacrylamide as a crosslinking agent. The crosslinking was initiated by ammonium persulfate with N,N,N′,N′‐tetramethylethylenediamine as an initiator. The water absorbency of crosslinked poly[AM‐co‐AA] was always higher than that of AHAMAA and was found to be correlated to the storage modulus of the polymers, which was higher for AHAMAA than that of crosslinked poly[AM‐co‐AA]. The residual aluminum concentration of AHAMAA (0.09–0.2 mg L^?1) indicated the stability of the polymer flocculant which was in good agreement with the observed tan δ and the higher G′′ and G′ values. Both the crosslinked poly[AM‐co‐AA] and AHAMAA satisfactorily reduced the turbidity of kaolin suspensions, but the latter gave a better reduction performance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of biodegradable block copolymers of poly(propylene fumarate‐co‐sebacate)‐co‐poly(ethylene glycol) and poly(ethylene fumarate‐co‐sebacate)‐co‐poly(ethylene glycol)

The synthesis of two low molecular weight linear unsaturated oligoester precursors, poly(propylene fumarate‐co‐sebacate) (PPFS) and poly(ethylene fumarate‐co‐sebacate) (PEFS), are described. PPFS, PEFS, and poly(ethylene glycol) are then used to prepare poly(propylene fumarate‐co‐sebacate)‐co‐poly(ethylene glycol) (PPFS‐co‐PEG) and poly(ethylene fumarate‐co‐sebacate)‐co‐poly(ethylene glycol) (PEFS‐co‐PEG) block copolymers. The products thus obtained are investigated in terms of the molecular weight, composition, structure, thermal properties, and solubility behavior. A number of design parameters including the molecular weights of PPFS, PEFS, and PEG, the reaction time in the polymer synthesis, and the weight ratio of PEG to PPFS or to PEFS are varied to assess their effects on the product yield and properties. The hydrolytic degradation of PPFS‐co‐PEG and PEFS‐co‐PEG in an isotonic buffer (pH 7.4, 37°C) is investigated, and it is found that the fumarate ester bond cleaves faster than does the sebacate ester bond. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 295–300, 2004     

pH and thermo‐responsive poly(N‐isopropylacrylamide) copolymer grafted to poly(ethylene glycol)

pH and thermo‐responsive graft copolymers are reported where thermo‐responsive poly(N‐isopropylacrylamide) [poly(NIPAAm), poly A ], poly(N‐isopropylacrylamide‐co‐2‐(diethylamino) ethyl methacrylate) [poly(NIPAAm‐co‐DEA), poly B ], and poly(N‐isopropylacrylamide‐co‐methacrylic acid) [poly(NIPAAm‐co‐MAA), poly C ] have been installed to benzaldehyde grafted polyethylene glycol (PEG) back bone following introducing a pH responsive benzoic‐imine bond. All the prepared graft copolymers for PEG‐g‐poly(NIPAAm) [ P‐N1 ], PEG‐g‐poly(NIPAAm‐co‐DEA) [ P‐N2 ], and PEG‐g‐poly(NIPAAm‐co‐MAA) [ P‐N3 ] were characterized by ¹H‐NMR to assure the successful synthesis of the expected polymers. Molecular weight of all synthesized polymers was evaluated following gel permeation chromatography. The lower critical solution temperature of graft copolymers varied significantly when grafted to benzaldehyde containing PEG and after further functionalization of copolymer based poly(NIPAAm). The contact angle experiment showed the changes in hydrophilic/hydrophobic behavior when the polymers were exposed to different pH and temperature. Particle size measurement investigation by dynamic light scattering was performed to rectify thermo and pH responsiveness of all prepared polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of poly(divinylbenzene‐co‐N‐isopropylacrylamide) microspheres and their hydrogen‐bonding assembly behavior for raspberry‐like core‐corona polymer composite

Narrowdisperse poly(divinylbenzene‐co‐N‐isopropylacrylamide) (poly(DVB‐co‐NIPAM)) functional microspheres with the diameter in the range of 630 nm and 2.58 μm were prepared by distillation–precipitation polymerization in neat acetonitrile in the absence of any stabilizer. The effect of N‐isopropylacrylamide (NIPAM) ratio in the comonomer feed on the morphology of the resultant polymer particles was investigated in detail with divinylbenzene (DVB) as crosslinker and 2,2′‐azobisisobutyronitrile (AIBN) as initiator. The monodisperse poly(DVB‐co‐NIPAM) microspheres with NIPAM fraction of 20 wt % were selected for the preparation of raspberry‐like core‐corona polymer composite by the hydrogen‐bonding self‐assembly heterocoagulation with poly(ethyleneglycol dimethacrylate‐co‐acrylic acid) [poly(EGDMA‐co‐AA)] nanospheres. Both of the functional poly(DVB‐co‐NIPAM) microspheres and the core‐corona particles were characterized with scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and elemental analysis (EA). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1350–1357, 2007     

Preparation and biodegradation of hydroxyl terminated poly(fumaric acid‐co‐diethylene glycol) and its segmented polyurethane

Hydroxyl terminated poly(fumaric acid‐co‐diethylene glycol), poly(FA‐co‐DEG) was prepared by melt polycondensation. The resultant unsaturated aliphatic polyester was characterized by Fourier transform infrared (FTIR) spectroscopy, hydroxyl value, acid value, and intrinsic viscosity. Its enzymatic degradation and crosslinking behavior as well as the effect of crosslinking degree on enzymatic degradation were also investigated. The crosslinking degree and reduction of carbon–carbon double bonds revealed excellent self‐crosslinking nature of poly(FA‐co‐DEG) at high temperature. The results of enzymatic degradation showed that poly(FA‐co‐DEG) has excellent biodegradability and that the biodegradation can be controlled by the crosslinking degree. Polyurethane was prepared by the reaction of poly(FA‐co‐DEG), 2,4‐toluene diisocyanate (TDI), and 1,4‐butanediol (BD). It was found that the biodegradation of the obtained polyurethane was slower than that of the original unsaturated aliphatic polyester poly(FA‐co‐DEG). The peeling strength of the polyurethane was very high, supporting better adhesion property with enhanced crosslinking. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Use of short isobornyl methacrylate building blocks to improve the heat and oil resistance of thermoplastic elastomers via RAFT emulsion polymerization

Triblock copolymer (TCP)‐based thermoplastic elastomers (TPEs) were designed via reversible addition–fragmentation chain‐transfer emulsion polymerization. Short isobornyl methacrylate (IM) building blocks in the two ends of molecular chain were incorporated to guarantee the mechanical properties of the TPEs at high temperature (i.e., heat resistance) because of the high glass‐transition temperature (T_g) of poly(isobornyl methacrylate) (PIM; ～180 °C). The microphase separation, tensile properties at different temperatures, dynamic mechanical properties, oil resistance, and thermal stability of the TPEs were extensively characterized. The TPEs had distinct microphase separation with a wide inter‐T_g interval (150–185 °C). The tensile strength and elongation at break of the TPEs decreased with increasing temperature from 25 to 100 °C because of the reduced interactions in the phase domain. Even so, the TPEs had a high elongation at break beyond 200% and little change in the tensile strength even at 100 °C together with a wide quasi‐platform stage between the T_g values in dynamic mechanical analysis; this indicated good heat resistance. Meanwhile, the TPEs had an enhanced oil resistance and a thermal stability higher than 300 °C. These TCP‐based TPEs with heat and oil resistance broaden the application potential in practical fields. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45379.     

Syntheses and electric conductivities of poly (methyl vinyl ketone–co–maleic anhydride)s reacted with phosphorus oxychloride

Electric conductivity of poly (methyl vinyl ketone-co-maleic anhydride) (poly (MVK-co-MAH)) reacted with phosphorus oxychloride was investigated. It was found that conductivities were strongly dependent on the POCl₃ treatment time and concentration for poly (MVK-co-MAH), but were not appreciably affected by the mol fraction of [MAH] and copolymerization temperature when the precursor copolymer was obtained. The conductivities of the poly (MVK-co-MAH)s treated with POCl₃ were of the order of 10^-6 to 10^-9S cm^-1. The conductivity of the poly (MVK-co-MAH) increased with the treatment time and concentrations of POCl₃. © 1993 John Wiley & Sons, Inc.     

Effect of surface functionalization on the physicomechanical properties of a novel biofunctional copolymer

The physicomechanical properties of functionally active poly(hydroxyethyl methacrylate‐co‐methyl methacrylate) [poly(HEMA‐co‐MMA)] are evaluated. It has been reported that the surface phosphorylated poly(HEMA‐co‐MMA) is capable of eliciting direct bone bonding when implanted in vivo. Hence, it is important to examine the physicomechanical property of the copolymer as a function of surface modification. The properties assessed are differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), equilibrium swelling, compressive strength, and dynamic mechanical analysis. According to the DSC data, the glass transition temperature, T_g of poly(HEMA‐co‐MMA) is not significantly altered by surface phosphorylation. The TGA results demonstrated that unmodified and surface phosphorylated copolymers have similar degradation profile. The differential thermal analysis further supports the data. The equilibrium swelling of functionalized poly(HEMA‐co‐MMA) in phosphate buffer saline ascertained that surface phosphorylation significantly increased the hydrophilicity of the copolymer. The study further illustrated that the percentage of equilibrium swelling appreciably increases with increase in HEMA content in the copolymer and reached a plateau after 100 h. Both compressive strength and compressive modulus of poly (HEMA‐co‐MMA) decreased due to surface phosphorylation while dynamic storage modulus value was not altered. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011