Synthesis and characterization of novel poly(dimethylsiloxane)/polyindole composites

A series of composites of polyindole (PIN) and poly(dimethylsiloxane) (PDMS) were synthesized chemically using FeCl₃ as an oxidant agent in anhydrous media. The composites were characterized by FTIR and UV‐visible spectroscopies, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X‐ray diffraction (XRD), elemental analysis, inductively coupled plasma‐optic emission spectroscopy (ICP‐OES), magnetic susceptibility, stress–strain experiments, and conductivity measurements. The conductivities of PIN at different temperatures were also measured and it was revealed that their conductivities were slightly increased with increasing temperature. Moreover, the freestanding films of PDMS/PIN composites were prepared by casting on glass Petri dishes to examine their stress–strain properties. From thermogravimetric analysis results it was found that PDMS/PIN composites were thermally more stable than PIN. Thermal stabilities of PDMS/PIN composites increased with increasing PIN content. It was found that the conductivities of PDMS/PIN composites depend on the indole content in the composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal behavior and surface morphology studies on polystyrene grafted sago starch

Polystyrene grafting onto sago starch was carried out by using ceric ammonium nitrate as a redox initiator. The grafted copolymers were characterized by FTIR, thermogravimetry (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). FTIR spectra analysis of the grafted chain and commercial polystyrene was identical, indicating that styrene was successfully grafted onto sago starch. TGA thermograms and analysis of DSC curves showed that the thermal stability of starch increases as a result of grafting. SEM micrographs showed the deformed prolate ellipsoidal shape of sago starch particles and this shape disappeared in polystyrene grafted sago starch being replaced with a spongy surface with pores. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2053–2058, 2003     

Density‐based phase‐separation asymmetric polyethylene–poly(dimethyl siloxane) blend membranes: Preparation and properties

A new concept of density‐based phase separation for the preparation of asymmetric membranes from polyethylene (PE) blended with liquid poly(dimethyl siloxane) (PDMS) has been tried. The PE/PDMS membranes were prepared via high‐temperature solution casting. The purpose of incorporating PDMS was to utilize its flexibility, relatively high density in comparison with PE, and dissolution in common solvent for the formation of asymmetric PE/PDMS membranes. The study has been carried out with 1.25, 2.5, 5, and 10% (v/w) loading of PDMS. A host of techniques were used to study morphology of PE/PDMS blend membranes. The membranes show nodular structure on surfaces in contact with solvent vapor environment, whereas the opposite surfaces have smoother texture devoid of nodules. Although differential scanning calorimetric (DSC) melting endotherms indicate enhancement of crystallinity with PDMS addition, chemical etching and subsequent scanning electron microscopic (SEM) observations show increasingly ordered spherulitic pattern on individual nodules with the incorporation of PDMS up to 2.5%. The density of the films also increases with the addition of PDMS as compared to the control. ATR‐FTIR data revealed asymmetric distribution of PDMS in membranes with more PDMS retention toward lower surface of membranes. Membrane cross sections were indicative of graded porosity with increasing pore size toward the bottom surface of membranes. The results were explained in terms of density‐based phase separation.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91:2278–2287, 2004     

Synthesis and characterization of semi‐interpenetrating networks based on poly(dimethylsiloxane) and poly(vinyl alcohol)

Semi‐interpenetrating networks (Semi‐IPNs) with different compositions were prepared from poly(dimethylsiloxane) (PDMS), tetraethylorthosilicate (TEOS), and poly(vinyl alcohol) (PVA) by the sol‐gel process in this study. The characterization of the PDMS/PVA semi‐IPN was carried out using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and swelling measurements. The presence of PVA domains dispersed in the PDMS network disrupted the network and allowed PDMS to crystallize, as observed by the crystallization and melting peaks in the DSC analyses. Because of the presence of hydrophilic (? OH) and hydrophobic (Si? (CH₃)₂) domains, there was an appropriate hydrophylic/hydrophobic balance in the semi‐IPNs prepared, which led to a maximum equilibrium water content of ～ 14 wt % without a loss in the ability to swell less polar solvents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

In vitro blood compatibility of modified PDMS surfaces as superhydrophobic and superhydrophilic materials

The surface of polydimethylsiloxane rubber (PDMS) was irradiated by a CO₂‐pulsed laser. The irradiated surfaces were grafted by hydroxyethylmethacrylate phosphatidylcholine (HEMAPC) by using the preirradiation method. The laser‐treated surfaces and HEMAPC‐grafted PDMS surfaces were characterized by using a variety of techniques including ATR‐FTIR spectroscopy, scanning electron microscopy (SEM), and wettability, which was measured by a water‐drop contact angle. Different surfaces with different wettability were prepared. These surfaces, including untreated PDMS (hydrophobic), laser‐treated PDMS (superhydrophobic), and HEMAPC‐grafted surfaces (superhydrophilic), were used for a platelet adhesion study. Results from in vitro testing indicated that chemical structures, such as negative‐charge polar groups and wettability, are important factors in blood compatibility of these surfaces and the superhydrophilic (the most wettable) and the superhydrophobic (the most unwettable) of modified PDMS surfaces have excellent blood compatibility compared to the unmodified PDMS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91:2042–2047, 2004     

Influence of titanium dioxide on crystallization behavior of an ethylene–propylene copolymer

Crystallization of an ethylene–propylene copolymer (E/P) filled with diverse weight percentages of titanium dioxide (TiO₂) was performed under isothermal and nonisothermal conditions to investigate the influence of the inorganic substance on the nucleation and growth mechanisms of the matrix. The overall and radial crystallization rates of the composite materials were measured using, respectively, differential scanning calorimetry (DSC) and optical microscopy. The nucleation density of E/P spherulites as a function of composition was investigated by scanning electron microscopy (SEM), revealing a nucleating effect of TiO₂. A comparison between the spherulitic texture of specimens showed a higher fineness of the composites relative to the neat matrix, whereas no changes of surface nucleation density were appreciable among composites within the explored compositional range. The thermal behavior is discussed in the light of the enhanced thermal conductivity of polymer composites, which conciliates the crystallization kinetics of the matrix, analyzed using the Avrami equation, to optical and SEM observations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3409–3416, 2003     

PF/PDMS-OH流变性能对其泡沫材料泡孔结构的影响

分别将质量分数为10%,15%和20%的端羟基聚硅氧烷(PDMS–OH)通过机械共混的方法改性酚醛树脂(PF),进而采用化学发泡的方法制备PF/PDMS–OH泡沫复合材料。采用旋转式流变仪表征共混体系的稳态及动态流变性能,研究黏弹性对树脂发泡过程的影响。傅立叶变换红外光谱表征PDMS–OH与树脂在固化过程中的化学反应。扫描电镜表征不同共混体系下泡孔的结构与形态。结果表明,加入15%PDMS–OH的共混体系具有最利于发泡成型的黏弹性,且可与PF形成化学交联作用,对PF泡沫的泡孔形态影响显著。同时红外表征显示,PDMS–OH与PF在固化过程中发生化学交联,这种互穿交联网状结构为PF及泡沫提供了更多稳定的柔性链段。     

玻璃纤维增强聚甲醛复合材料性能与结构的研究

制备了一系列玻璃纤维增强聚甲醛(POM/GF)复合材料,采用傅立叶变换红外光谱仪、差示扫描量热仪、扫描电子显微镜及万能材料试验机等对POM/GF复合材料的结构与力学性能进行了研究,并详细考察了增容剂二苯基亚甲基二异氰酸酯(MDI)的不同添加量对复合材料性能的影响.结果表明,MDI的加入使得POM/GF复合材料的性能显著提高,并在其添加量为POM质量的0.7%时具有最佳性能.     

Blends of poly(propylene) and polyacetal compatibilized by ethylene vinyl alcohol copolymers

Polymer blends of poly(propylene) (PP) and polyacetal (polyoxymethylene, POM) with ethylene vinyl alcohol (EVOH) copolymers were investigated by differential scanning calorimetry (DSC), rheological, tensile, and impact measurements, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The PP–POM–EVOH blends were extruded with a co‐rotating twin‐screw extruder. The ethylene group in the EVOH is partially miscible with PP, whereas the hydroxyl group in the EVOH can form hydrogen bonding with POM. The EVOH tends to reside along the interface, acting as a surfactant to reduce the interfacial tension and to increase the interfacial adhesion between the blends. Results from SEM and mechanical tests indicate that a small quantity of the EVOH copolymer or a smaller vinyl alcohol content in the EVOH copolymer results in a better compatibilized blend in terms of finer phase domains and better mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1471–1477, 2003     

Effect of the type of plasma on the polydimethylsiloxane/collagen composites adhesive properties

Polydimethylsiloxane (PDMS) films were treated with either oxygen (O₂), nitrogen (N₂) or argon (Ar) plasma between 40 W and 120 W for 5–15 min and their surface properties studied by contact angle measurements, infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Lower contact angles and increases in surface roughness, assessed by SEM and AFM, were observed for all used gases when plasma power and time increased, with argon treatment being the one that showed the most significant change in roughness.PDMS/collagen type I composites obtained after treating PDMS with oxygen at 80 W for 13 min or nitrogen and argon at 80 W for 14 min showed a peel strength of 0.1N/mm (oxygen plasma), 0.08 N/mm (nitrogen plasma) and 0.09 N/mm (argon plasma). In all cases, peel strength was higher than that measured for the untreated bilayer composite. An increase in adhesion strength, after oxygen and nitrogen plasma, was mostly attributed to chemical interaction between functional groups introduced on the PDMS surface and the functional groups on collagen as detected by FTIR. In contrast, the high peel strength observed on PDMS treated with argon plasma was attributed to its increased roughness which in turn increased mechanical interlocking. The properties of these composites render them suitable for adhesive free skin substitutes.     

Poly(vinylidene fluoride) with zinc oxide and carbon nanotubes applied to pressure sheath layers in oil and gas pipelines

In this work, PVDF composites containing 0.2% (m/m) of carbon nanotubes (MWCNTs), PVDF with 5.0% (m/m) of zinc oxide (ZnO), and composites containing both particles in the same contents in the matrix were melt processed in a mini-extruder machine with double screws, using the counter-rotation mode. Composites were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), dynamic-mechanical analysis (DMA), and contact angle tests (CA). The samples presented the predominance of the α phase, with an increased degree of crystallinity as well as an increase in dimensional stability by incorporating both fillers, showing a synergistic effect between these particles, as shown on FTIR, DSC, and XRD results. SEM images showed a good dispersion of high aspect ratio particles. In general, DMA and TGA analysis showed that composites had not decreased their thermal and mechanical performance when compared to neat PVDF. Results of CA analysis showed an increase in the hydrophobicity of the sample containing MWCNTs. Permeability tests were also performed using a differential pressure system, combining high temperature and pressure, obtaining permeability measures and time lag. This work presents an alternative of composite materials, suggesting its application in the internal pressure sheath layers of oil and gas flexible pipes.     

Effect of kenaf fiber age on PLLA composite properties

A challenge facing engineering with natural fibers is the high standard deviation of mechanical properties of natural fiber compared with synthetic fiber. Plants have a chemical and physical architecture reflective of their age. The region near the apex is more flexible than that near the base. In this paper we investigate the impact of increasing age of plant fiber on the corresponding composite. Bast fibers stems of kenaf (Hibiscus cannabinus, L.), a warm season tropical herbaceous annual plant extracted corresponding to different age, were dispersed into Poly‐l ‐lactide (PLLA) matrix by melt blending followed by compression molding. The resulting bio‐based hybrid composites were characterized by X‐ray diffraction (XRD), attenuated total reflectance‐Fourier transfer infrared spectroscopy (ATR‐FTIR), differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were conducted. DSC and XRD indicated that the kenaf was effective in promoting crystallization. TGA indicated that the thermal stability of composites is reduced compared with PLLA, but the older fiber sample based on 120–150 cm from the plant apex improved thermal stability compared with the rest. SEM and OM inferred good fiber dispersion while dynamic mechanical tests revealed increased modulus. POLYM. COMPOS., 35:915–924, 2014. © 2013 Society of Plastics Engineers     

Tire rubber–sisal composites: Effect of mercerization and acetylation on reinforcement

Tire rubber particles were mixed randomly with short sisal fibers and hot pressed. Sisal fibers were used as received, mercerized, and mercerized/acetylated. The fibers were characterized by scanning electron microscopy (SEM), thermal gravimetry analysis (TGA), infrared spectroscopy (FTIR), water sorption, and mechanical properties. Thermal stability of the mercerized/acetylated fibers improves (from 200 to 300°C) with respect to the raw fibers, and water sorption is ～ 20% smaller than for the raw and the mercerized fibers. Tensile strength is unchanged after the chemical treatments. Water sorption, mechanical properties, and SEM evaluated the performance of the tire rubber composites. All composites showed enhanced elastic modulus; increase is dependent on fiber load. Smallest water sorption was obtained in composites with the mercerized/acetylated fibers. With these fibers at 10% load, the best results were obtained with the smaller tire rubber particles (320 μm) and at 5% load with the bigger (740 μm) tire rubber particles. Both composites showed ～ 50% increase in tensile strength when compared to similar composites with raw fibers. SEM of the surface of fracture showed that the adhesion between fiber and rubber was enhanced after both chemical treatments. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2507–2515, 2003     

The Effect of the Ionizing Radiation on Hydroxyapatite–Polydimethylsiloxane Layers

The bio hydroxyapatite (HAp) was used from a long time in different medical and environmental applications. The HAp layers with a uniform surface were used for various medical applications such as orthopedic and dental metal implants. In this work, we reported on the influence of X‐ray radiation on the structural and morphological properties of composite layers based on HAp and polydimethylsiloxane (PDMS) deposited on titanium substrates. The HAp:PDMS layers were investigated by different complementary methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and glow discharge optical emission spectrometry (GDOES). FTIR spectral analysis showed that the molecular structure of the coatings was not changed after their irradiation even though, the depth profile analysis performed by GDOES indicated a depletion of Ca and P elements from the HAp:PDMS irradiated samples. By SEM, we showed that the morphological features of the coatings were also changed, as the irradiated layers are delaminated. The biological assays confirmed that the antibacterial activity of HAp:PDMS composite layers increased after irradiation. The results obtained in this study highlighted that the biological properties of HAp:PDMS layers could be influenced by irradiation. POLYM. ENG. SCI., 59:2406–2412, 2019. © 2019 Society of Plastics Engineers     

Synthesis and characterization of novel organosilicon-modified polyurethane

Organosilicon-modified polyurethane have been synthesized using the prepolymer method and characterized by Fourier infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), solvent resistance analysis, and stress–strain tests. The FTIR spectra show that the polyurethane is fully reacted and polydimethylsiloxane (PDMS) is chemically incorporated into the copolymer. SEM reveals a multiphase structure with surface cracking and thermal analysis indicates that the heat resistance properties are better when the PDMS concentration is low. According to the solvent resistance, water and acetone uptake decreases when the PDMS content is less than 4 wt % while the ethanol uptake changes indistinctively. The mechanical properties of the films are also discussed. A tensile strength up to 6 wt % has the largest effect while the elongation at break decreases. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125:1486–1492, 2012     

Preparation and characterization of poly (vinyl butyral)‐leather fiber composites

This study reports the preparation and characterization of composites with recycled poly (vinyl butyral) (PVB) and wet blue leather fiber with leather contents of 30, 50, and 70 wt%, using an extruder equipped with a Maillefer single screw operated with a flat extrusion die. The components of the composites were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and Fourier transform infrared spectroscopy (FTIR). After extrusion, the PVB/leather composite plates were compression‐molded to obtain specimens for testing the tensile properties, hardness, abrasion resistance, and tear strength. The morphologies of the composites were analyzed by scanning electron microscopy (SEM). The DMA and FTIR analyses showed that the recycled PVB contained plasticizer remained in the polymer matrix after extrusion. The SEM analysis revealed good interfacial adhesion between the PVB matrix and the leather fibers. Increasing the leather content in the composites led to a significant increase in the tensile modulus and a reduction in the tensile strain at breaks. The Shore hardness of the composites increased with the wt% of leather, whereas the abrasion resistance decreased. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers.     

Preparation of thermoplastic polyurethane/graphene oxide composite scaffolds by thermally induced phase separation

In this study, biomedical thermoplastic polyurethane/graphene oxide (TPU/GO) composite scaffolds were successfully prepared using the thermally induced phase separation (TIPS) technique. The microstructure, morphology, and thermal and mechanical properties of the scaffolds were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and compression tests. Furthermore, NIH 3T3 fibroblast cell viability on the porous scaffolds was investigated via live/dead fluorescent staining and SEM observation. FTIR and Raman results verified the presence of GO in the composites. SEM images showed that the average pore diameter of the composite scaffolds decreased as the amount of GO increased. Additionally, the surface of the specimens became rougher due to the embedded GO. The compressive modulus of composite specimens was increased by nearly 200% and 300% with the addition of 5% and 10% GO, respectively, as compared with pristine TPU. 3T3 fibroblast culture results showed that GO had no apparent cytotoxicity. However, high loading levels of GO may delay cell proliferation on the specimens. POLYM. COMPOS., 35:1408–1417, 2014. © 2013 Society of Plastics Engineers     

Influences of Ternary Graft Copolymers on the Morphology and Properties of Polypropylene/Calcium Carbonate Composites

The ternary graft copolymers were synthesized by solid-phase grafting maleic anhydride (MAH), methyl methacrylate (MMA), and butyl acrylate (BA) onto polypropylene (PP), and applied in the interfacial modification of the PP/Calcium carbonate (CaCO₃) composites. Fourier transform infrared (FTIR) spectroscopy was used to analyze the structure of the ternary graft copolymers. Scanning electron microscopy (SEM), thermogravimetry (TG), differential scanning calorimetry (DSC), and dynamic rheological testing were used to investigate the morphology and the properties of the composites. FTIR results confirmed the occurrence of the solid-phase graft copolymerization, and SEM exhibited the improvement of the compatibility between PP and CaCO₃ by PPTM. The properties testing showed that PPTM significantly contributed to the reinforcement of the composites in terms of mechanical properties, thermal properties, and rheological properties by acting as interfacial modifiers and plasticizers. The preferable loadings of PPTM for the properties improvement of the PP/CaCO₃ composites were between 7 and 9 phr.     

PLA/MCC复合材料的制备及其性能

以水稻秸秆经碱解、酸解得到的微晶纤维素(MCC)作为聚乳酸(PLA)的改性材料,通过溶液共混、流延成膜制备了PLA/MCC复合膜,采用傅里叶变换红外光谱仪、差示扫描量热仪、扫描电子显微镜等对其性能进行了表征。结果表明:水稻秸秆中木质素、半纤维素等杂质大部分被有效除去,当NaOH质量分数为5%时,去除率最大,MCC成功制备;当MCC质量分数为8.3%时,可以最大程度改善PLA/MCC复合膜的拉伸性能,MCC与PLA结合最好,而MCC的加入会使复合膜的热稳定性有所降低。     

High‐density polyethylene modified by polydimethylsiloxane

High‐density polyethylene (HDPE) was modified by the grafting of polydimethylsiloxane (PDMS) through a free‐radical process, in a melt‐mixer chamber, using dicumyl peroxide (DCP) as an initiator. The influence of PDMS (0.2–0.8 mol %) and peroxide (0.03–0.08 mol %) concentrations on the grafting, final torque, and melt flow rate (MFR) of copolymers were investigated using factorial planning. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), MFR, and rheometry were used to characterize the copolymers obtained. Surface plots showed that higher degrees of grafted PDMS and higher final torques were obtained with increase in the PDMS amount at low DCP levels and with increase in the DCP amount at low PDMS levels. The peaks of fusion and crystallization of the copolymers showed no significant changes with respect to HDPE. Data of MFR and GPC suggested that crosslinking reactions and/or chain extension occurred concomitant with the grafting reactions. Copolymers with high grafting degrees showed high MFR and low dynamic shear viscosities in comparison with low grafting degree copolymers, which is probably due to the migration of the PDMS‐containing copolymers on the surface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3460–3467, 2001