Waste pine cones as a source of reinforcing fillers for thermoplastic composites

In this study, we evaluated some physical and mechanical properties of polypropylene (PP) composites reinforced with pine‐cone flour and wood flour. Five types of wood–plastic composites (WPCs) were prepared from mixtures of cone flour, wood flour, PP, and a coupling agent. The water resistance and flexural properties of the composites were negatively affected by an increase in cone‐flour content. Extractives in the cone flour had a significant effect on the flexural properties of the WPCs. However, the flexural properties and water resistance of the WPC samples were not significantly affected by the addition of 10 wt % of the cone flour when compared to the WPC samples made from wood flour. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A novel preparation method of polyaluminum chloride/polyacrylamide composite coagulant: Composition and characteristic

Inorganic/organic composite coagulants have drawn a wide attention through the years owing to its superior coagulation behaviors. In this study, polyaluminum chloride (PAC)/polyacrylamide (PAM) composite coagulant was synthesized by ultraviolet (UV) irradiation by using PAC and acrylamide (AM) as raw materials, urea as a solubilizer, and 2,2′‐Azobis[2‐(2‐imidazolin‐2‐yl)propane]dihydrochloride (VA‐044) as an initiator. The effect of total monomer mass fraction, solubilizer dosage and initiator dosage on the viscosity and molecular weight of PAC/PAM composite coagulant was discussed. The results suggest that the composite coagulant with high polymerization degree, intrinsic viscosity of 1483 mL/g and molecular weight of 7.38 million, could be obtained when the total monomer mass fraction of 40%, urea dosage of 1.5% and initiator dosage of 0.6% are chosen in the preparation. It is a potential preparation method of composite coagulant with short preparation time and high preparation efficiency. Fourier transform infrared spectrum and ¹H nuclear magnetic resonance spectroscopy represent that the coagulant for polyaluminum chloride and polypropylene are copolymer. Thermal gravimetric analysis describes the high thermal stability of composite coagulant. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44500.     

PP基木塑复合材料热稳定性研究进展

分析了聚丙烯(PP)基木塑复合材料中各组分的热稳定性,综述了PP基木塑复合材料热稳定性的研究进展,主要是植物纤维、偶联剂、抗氧剂、阻燃剂、弹性体等对复合材料热稳定性的影响。     

Preparation of pectin‐inorganic composite material as accumulative material of metal ions

Pectin is one of the biopolymers in the cell walls of all plant tissues, but the pectin‐containing materials have been discarded as industrial waste in food‐processing factories. We prepared a water‐insoluble pectin‐inorganic composite material by mixing pectin and a silane coupling reagent, bis(3‐trimethoxysilylpropyl)amine. The mechanical strength of the pectin‐inorganic composite material was higher than that of the pectin material without the addition of an inorganic component. In addition, the thermal stability of the composite material increased with the addition of the inorganic component. Furthermore, when the pectin‐inorganic composite materials were incubated in an aqueous solution of Cu(II), Zn(II), or In(III), these composite materials effectively accumulated not only the heavy metal ions, but also rare‐earth metal ions. Additionally, based on the infrared (IR) measurements, the metal ion accumulative mechanism into the composite material is described. As a result, the IR spectra suggested an electrostatic interaction between the metal ion and carboxy group in the pectin. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42056.     

Novel thermosets obtained by the ring‐opening metathesis polymerization of a functionalized vegetable oil and dicyclopentadiene

New polymeric thermosetting resins prepared by the ring‐opening metathesis polymerization (ROMP) of a commercially available vegetable oil derivative, Dilulin, and dicyclopentadiene (DCPD) have been prepared and characterized. A thorough characterization of the modified oil itself has been carried out to elucidate its structure. Grubbs' second‐generation catalyst has been used to effect the ROMP of the strained unsaturated norbornene‐like rings in the commercial oil. Dynamic mechanical analysis of the resulting thermosetting resins has revealed that glass‐transition temperatures ranging from 36 to ?29°C can be obtained when the proper ratio of oil to DCPD is employed. Thermogravimetric analysis has revealed that these resins have very similar temperatures of maximum degradation. Extraction analysis has indicated that all the samples had at least a 20% soluble fraction and that the soluble fraction was composed of oligomers, unreacted triglyceride oil, or both. The effect of the soluble fraction as a plasticizer has also been explored. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

PVC木塑复合材料热解动力学

将木粉按一定比例添加到PVC中得到复合材料,通过热重分析研究复合材料在空气、N2气氛下不同升温速率时的热解行为。通过Doyle和Tang method法计算了木塑材料的降解活化能。利用活化能分布函数,分析了复合材料在热解、燃烧过程中不同阶段的反应活性变化规律。研究表明,热解过程可分为3个阶段,230～360℃为第一失重阶段,360～430℃为稳定阶段,430～580℃为第二失重阶段。升温速率及反应气氛对热解过程有显著影响。由分布活化能模型计算表明,其热解动力学为一级反应,两个失重阶段的活化能分别为220kJ·mol-1和139kJ·mol-1,反应活性随失重率的增加而减少。     

Preparation and antimicrobial activity of sulfopropyl chitosan in an ionic liquid aqueous solution

To improve the solubility and antibacterial activity of chitosan and expand its applications, we synthesized sulfopropyl chitosan (SP‐CS) with various degrees of substitution (DSs) under mild and green reaction conditions in the aqueous solution of an ionic liquid by a green process. The chemical structures of the polymers were verified by Fourier transform infrared spectroscopy and ¹H‐NMR, and the thermal stability was studied by thermogravimetric analysis. After modification, the water solubility of chitosan was improved significantly, and SP‐CS showed excellent solubility in water at neutral pH. The antibacterial activities of the SP‐CSs with various DSs were systematically studied for the first time by the Oxford cup method and optical density method. The results suggest that the antimicrobial properties of SP‐CS were enhanced by the introduction of sulfopropyl and increased with increasing DS. The application of chitosan could be expanded, and SP‐CS has the potential to be used as a water‐soluble antimicrobial. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44989.     

Mechanical properties of recycled kenaf/polyethylene terephthalate (PET) fiber reinforced polyoxymethylene (POM) hybrid composite

Environmental concerns have attracted researchers to study the recycling of composite materials and thermoplastics due to the desire not to waste materials and reduce disposal of scraps that may eventually pollute the environment. The main objective of this article is to study the effect of recycling on the mechanical properties of kenaf fiber/PET reinforced POM hybrid composite. The virgin hybrid composite was produced by compression molding and later subjected to mechanical testing. The scraps obtained after the mechanical testing were shredded, granulated and subjected to compression molding to produce samples for mechanical testing. Tensile strength of 27 MPa was obtained and (after second recycling process) which is lower compared to 73.8 MPa obtained for the virgin hybrid composite. There was a significant increase in flexural modulus (4.7 GPa) compared to the virgin hybrid composite. The impact strength dropped to 4.3 J cm^?1 as against 10.5 J cm^?1 for the virgin hybrid composite. The results of thermal degradation showed about 80% weight loss for kenaf fiber between 300 and 350°C. The weight loss may be due to the degradation of cellulose and hemicellulose content of the fiber. The percentage water absorption of the recycled composite dropped by about 80% compared to the virgin hybrid composite. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39831.     

Preparation of O‐carboxymethyl chitosans and their effect on color yield of acid dyes on silk

O‐Carboxymethyl chitosans with a low degree of substitution (DS) and a high degree of deacetylation (DD) were prepared directly from chitin and characterized by using ¹H‐NMR, ¹³C‐NMR, and elemental analysis methods. In our study, O‐carboxymethyl chitosans could increase the color yield of Acid Red 44 and Acid Green 25 on silk fabrics without lowering the corresponding washing fastness property. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2500–2502, 2003     

Controlled preparation and properties of acrylic acid epoxy-acrylate composite emulsion for self-crosslinking coatings

A stable epoxy-acrylate composite latex was successfully prepared through emulsion polymerization of modified epoxy acrylic (EPAC) oligomer with acrylate monomer. The EPAC oligomer was obtained using active acrylic acid (AA) to react with epoxy resin. And by regulating the reaction degree of the active hydrogen of AA and epoxide group, there is the acquisition of terminal double bond that gives EPAC reactivity, together with the partial retention of the epoxide group that enables self-crosslinking during film formation. The structural conformation of the oligomer was ascertained by Fourier transform infrared (FTIR) spectroscopy. The factors influencing the stability of the epoxy-acrylate composite latex were investigated. The epoxy-acrylate composite latex was the most stable when methyl acrylic acid was 1.5 wt% and modified EPAC oligomer was 15 wt% of the total monomer weight. The morphology and property of the composite latex films were characterized by scanning electron microscopy, transmission electron microscopy (TEM), and temperature-modulated differential scanning calorimetry (TOPEM-DSC). The results confirm that there is successful emulsion copolymerization between modified EPAC oligomer and acrylate monomer. TEM show that the particles of epoxy-acrylate composite have a core-shell structure, and there is no free epoxy resin. The FTIR and TOPEM-DSC results reveal that the copolymer emulsion possesses self-crosslinking ability. During film formation, self-crosslinking reaction occurs between epoxide groups with carboxyl groups, giving exothermal phenomena. The thermal stability as well as the corrosion resistance of the films was analyzed. The results show outstanding thermal stability as well as corrosion resistance attributable to the crosslinking reticulation structure. It is envisaged that the epoxy-acrylate composite latex has great potential in the development of high-performance aqueous coatings.     

Polyaniline/pillared montmorillonite clay composite nanofibers

In situ polymerization of aniline is done inside the pillared clay matrix. The nonswellable pillared clay confined matrix allows efficient polymerization that leads to nanofibrous morphology. As a result high polymer order and crystallinity is attained and is evident from XRD patterns. The strong interaction between the clay layers and polyaniline (PANI) is understood from FTIR and DRS spectra. Additionally these analytical results suggest that the prepared PANI is in the doped state. The PANI/pillared clay nanocomposite formation gives additional thermal stability to the polymer backbone and is clear from the DTG curves. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Tunable wettability and tensile strength of chitosan membranes using keratin microparticles as reinforcement

Keratin particles with microscale are prepared by ball mill and its influences on the chitosan membrane is evaluated. Composite membranes with various content of keratin are fabricated, and their physical and chemical properties such as morphology, wettability, crystallization, thermal stability, tensile strength, and break elongation are investigated. Optical microscope and situ topographic scan mode of nano‐test system are used to examine the dispersion and aggregation of keratin on the surface of chitosan membrane. The result of contact angle (CA) and mechanical testing show that the incorporation of keratin particles decrease the CA from 98.1° to 58.2°. Tensile strength and break elongation of the composite membrane reaches a maximum of 65 ± 8 MPa and 15% when the keratin content is 6%, an increase of 80% and 88% compared with the pristine chitosan membrane. Both the increase in tensile strength and break elongation is result of the incorporation of keratin particles known for their excellent compatibility between keratin and chitosan matrix. These kind of composite material combines the antibacterial properties of chitosan with cell culture preference of keratin which may have potential biomedical application. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44667.     

Preparation and application of magnetic chitosan in environmental remediation and other fields: A review

Magnetic chitosan has received considerable attention over the decades due to its low cost, biodegradability, green sources, magnetic intensity. In this review, we reviewed the preparation methods of magnetic chitosan using co-precipitation, cross-linking and electrochemical. Therein cross-linking methodologies involved in the reaction of amino groups are facile to introduce additional reaction groups and improve anti-swelling of chitosan layers, mostly in an acidic environment. Besides, we focused on the applications of magnetic chitosan in various fields such as wastewater treatment, for example, removal of heavy metal ions, organic/inorganic dyes, fluorides, and pesticides. Moreover, magnetic chitosan also reveals great potential application in the field of medical, pharmaceutical, food and electronic screening. Above all, magnetic chitosan is economically and operationally beneficial as it can be easily separated and controlled with an external magnetic field and can be modified to maximize its functions.     

Cationically cured natural oil‐based green composites: Effect of the natural oil and the agricultural fiber

Green composites were produced from various cationically cured natural oil‐based resins and agricultural fibers. The natural oils and agricultural fibers of interest included corn, soybean, fish, and linseed oils and corn stover, wheat straw (WS), and switchgrass fibers. The effects of the types of natural oil and agricultural fiber on the structure and thermal and mechanical properties of the composites were studied using Soxhlet extraction, thermogravimetric and dynamic mechanical analysis, and tensile testing. The green composites, with agricultural fiber loadings of 75 wt %, have thermal stabilities up to 275°C. The Young's moduli and tensile strengths of the composites ranged from 1590 to 2300 and 5.5 to 11.3 MPa, respectively. In general, an increase in the degree of unsaturation of the natural oil resulted in improvements in the thermal and mechanical properties of the composites. The WS fibers tended to give composites with the best thermal and mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Utilization of ramon seeds (Brosimum alicastrum swarts) as a new source material for thermoplastic starch production

The development and characterization of biodegradable polymers deriving from renewable natural sources has attracted much attention. The aim of this work was to partially characterize a thermoplastic starch obtained from the starch of seeds from the ramon tree (TPS‐RS) as an option to substitute thermoplastic starch from corn (TPS‐CS), in some of its applications. At 55% of relative humidity (RH), TPS‐RS had higher tensile strength and deformation than TPS‐CS. X‐ray diffraction analysis showed similar values in residual crystallinity (percentage of crystallinity that remains after plasticization process) in both TPS. The SEM micrographs showed a few remnant granular structures in the TPS‐RS. The FTIR showed a greater intensity in band at 1016 cm^?1 in the TPS‐CS and TPS‐RS in comparison with their corresponding native starch, indicating an increase in the amorphous region after plasticization. The TGA analysis showed greater thermal stability in TPS‐CS (340 °C) compared with TPS‐RS (327 °C). In addition, the glass transition temperature in both TPS was 24 °C. The results obtained represent a starting point to potentialize the use of TPS‐RS instead of TPS‐CS for the development of new biodegradable materials for practical applications in different areas. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44235.     

Enhancement of pervaporation performance of composite membranes through in situ generation of silver nanoparticles in poly(vinyl alcohol) matrix

Composite membranes were prepared from an aqueous solution of poly(vinyl alcohol) (PVA) and silver sulphate. The silver nanoparticles were generated in situ before crosslinking PVA matrix by reduction of silver ions using sodium borohydride. Physico‐chemical properties of the resulting composite membranes were studied using Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy (UV–vis), thermogravimetric analysis (TGA), Wide‐angle X‐ray diffraction (WAXD), scanning electron microscopy (SEM), and universal testing machine (UTM). The UV–vis spectrum shows a single peak at 410 nm due to surface plasmon absorption of silver nanoparticles. This surely specified that silver nanoparticles are generated in PVA matrix. The membranes were under go pervaporation (PV) for separation of water from isopropanol at different temperatures. The results indicated that hydrophilicity and amorphous nature of the membranes were increased with increasing silver nanoparticles in PVA matrix. The swelling and separation performance of the membranes were studied. Both permeation flux and separation factor were increased with increasing silver nanoparticles in PVA matrix. The results showed that the membrane containing 2.5 mass% of Ag salt exhibited excellent PV performance. The values of total flux and flux of water are almost closed to each other, indicating that membranes could be effectively used to break the azeotropic point of water‐isopropanol. The long‐term test was performed at room temperature and ascertained that membranes were durable up to 30 days for the dehydration of IPA. On the basis of the estimate Arrhenius activation energy values, the efficiency of the membranes was discussed. The calculated ΔH_s values are negative for all the membranes, indicating that Longmuir's mode of sorption is predominant. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41248.     

Investigation of the thermostability of poly(ethylene terephthalate)–hemp fiber composites: Extending natural fiber reinforcements to high‐melting thermoplastics

The thermal stability of poly(ethylene terephthalate) reinforced with 1, 5, 10, 15, and 20% hemp fibers was investigated with the aim of extending the applications of biocomposites to high‐melting thermoplastics. The material was injection‐molded following compounding with a torque‐based Rheomix at 240, 250, and 260°C. A combination of thermogravimetric methods at 5, 10, and 20°C/min, Liu and Yu's collecting temperature method, and Friedman's kinetic method were used for testing and analysis. A significant thermostability for all formulations was observed below 300°C; this demonstrated their potential for successful melt processing. Moreover, two degradation steps were observed in the temperature ranges 313–390 and 390–490°C. The associated apparent activation energies within the temperature ranges were determined as 150–262 and 182–242 kJ/mol, respectively. We found that the thermostability was significantly affected by the heating rates; however, the effect of the temperature of the mixing chamber was negligible. These findings suggest that the successful melt processing of high‐melting thermoplastics reinforced with natural fibers is possible with limited fiber thermodegradation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42500.     

Evaluation of the removal of n-butanol vapor by the poly(lactic acid)-zeolite-TiO2 composite and formation of by-products

The use of polymeric films incorporated with zeolite-TiO₂ composites associated with UV radiation can be an alternative in the removal of volatile organic compounds (VOCs) through the adsorption and photodegradation processes. This study produced poly(lactic acid) (PLA) films incorporated with 13× zeolite, TiO₂, and 13×-TiO₂ zeolite composite to remove n-butanol and evaluate the by-products generated in the process. The results showed that 13× zeolite and TiO₂ added individually or as a composite to PLA, gave the polymer matrix a significant increase in the removal capacity of n-butanol. The best performance was presented by the zeolite-TiO₂, composite, confirming a synergistic effect. However, the formation of CO and CO₂ exceeded the expected values, with the verification that the polymeric matrix underwent photodegradation action by TiO₂. The polymeric film only containing zeolite is the most suitable for the removal of VOCs, as it did not present degradation of the PLA, generating a lower concentration of by-products.     

Preparation of aerochitin‐TiO2 composite for efficient photocatalytic degradation of methylene blue

An aerochitin–titania (TiO₂) composite was successfully synthesized and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, and N₂ adsorption isotherms. The photocatalytic activity of the composite was investigated on the degradation of the model organic pollutant, methylene blue (MB) dye, under UV irradiation. The aerochitin–TiO₂ composite showed excellent adsorptive and photocatalytic activity with a degradation degree of 98% for MB. The first‐order rate constants for the photodegradation MB by TiO₂ nanoparticles and aerochitin–TiO₂ composite were found to be (3.49 ± 0.04) × 10^?3 and (1.82 ± 0.02) × 10^?2 min^?1. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45908.     

High‐resolution measurements of water permeability and solubility in microelectronic‐casing made of a hydrophobic polymeric composite

Exposing the composite polymeric casing of integrated circuits (ICs) to water results in miniscule water absorption, followed by its permeation throughout the packaging, and component damage. Studying water penetration and solubility mechanisms in the IC casing is crucial for understanding water‐related damage mechanisms and protection against them. The main analytical challenge, hereafter, stems from the need to study miniscule water amounts (<0.5 wt %) capable of penetrating the casing, despite its hydrophobic nature. In this article, a TGA has been employed to study the water uptake kinetics in the casing, and to decipher the related water penetration mechanisms. High‐resolution measurements of water adsorption and desorption profiles were performed, followed by calculations of the related activation energies and solubility enthalpies. These data were correlated with a relatively new model that assigned the primary locales of the adsorbed water to the compatible filler–polymer interface. Thus, water permeability is related to molecules hopping between these sites. Finally, we have shown that for the IC casing in our study, the activation energy of water permeation is related to the binding energy of H₂O onto the Si? O? Si groups at the fused‐silica‐filler surface, where they desorb, hop, and reabsorb. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4523–4527, 2006