Effect of PEGylated chitosan on plasma etched PET fabrics surface properties

In this work, PEGylated chitosan derivatives were prepared and used to modified poly(ethylene terephthalate) (PET) fabrics. PET fabrics surface were etched by oxygen plasma before different concentrations PEGylated chitosan derivatives solution treatment. The effects of oxygen plasma and PEGylated chitosan derivatives on the surface properties of PET fabrics are investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). Surface wettability was monitored by water contact angle measurement and moisture regains. The results showed that the occurrence of oxygen‐containing functional groups (i.e., C?O, C? O, and ? OH) of the plasma‐treated PET and the surface coarseness increased from those of the untreated one. There was a layer film formed on the surface of PET fabrics after PEGylated chitosan modification. The combination treatment of oxygen plasma with PEGylated chitosans lightly lowered the breaking strength and elongation of PET fabric. That moisture regains increased and the contact angle decreased implied the hydrophilicity enhancement for the PET fabrics. In addition, dyeing property of PEGylated chitosan derivative modified PET was improved. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39693.     

Comparison of the macroscale and microscale tests for measuring elastic properties of polydimethylsiloxane

Polydimethylsiloxane (PDMS) has many biomedical applications, since it is biocompatible, easy to fabricate and inexpensive. The response of biological cells and tissues is affected by the mechanical properties of the PDMS surface, which can be controlled by varying the crosslinking percentage. It is essential to find reliable ways to measure elastic properties of PDMS prepared with different surface conditions or stiffness gradients. In this paper, the elastic modulus of PDMS was measured at different scales as a function of the crosslinking percentage varied from 2% to 9%. Macroscopic compression and tension tests were used and compared with the nano‐JKR (Johnson‐Kendall‐Roberts) method applied to a microindentation test. Depending on the test, the PDMS elastic modulus increased from 10 to 85 fold with the crosslinking percentage change from 2% to 9%. The PDMS elastic modulus varied as a sigmoid function with the crosslinking percentage for each type of test. The compression macroscale test is the easiest way to estimate the elastic modulus of stiffer PDMS with higher crosslinking percentage. For the more compliant and tacky PDMS samples with lower crosslinking percentage the nano‐JKR test is more suitable, as it is sensitive and accounts for the surface adhesion forces. The samples with the lower crosslinking percentage are much less stiff in tension than in compression, resembling liquid‐like behavior. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42680.     

Silver nanowire network embedded in polydimethylsiloxane as stretchable,transparent, and conductive substrates

Highly stretchable transparent conductors where Ag nanowire networks (AgNWs) are reliably embedded into a polydimethylsiloxane (PDMS) substrate are presented. In spite of the weak physical and chemical interaction between Ag nanowires and PDMS, a significantly high transfer efficiency and uniform embedding of AgNW percolation mesh electrodes into PDMS was achieved by simply coating aerogels onto the AgNWs and using water‐assisted transfer. By the failure‐free transfer and reliable bonding with the substrate, the conductive PDMS with embedded AgNWs that exhibits a sheet resistance (R_s) of 15 Ω/sq and 80% optical transmittance (T) are reported here. The PDMS films accommodate tensile strains up to 70% and a cyclic strain of 25% for more than 100 cycles, with subsequent R_s values as low as 90 and 27 Ω/sq, respectively. The T of this conductive PDMS is more than 25% higher than that of networks of CNTs, Cu nanowires, and hybrid composites of CNTs and graphene embedded in elastomer films such as PDMS, polyurethane, and Ecoflex. The simple and reproducible fabrication allows the extensive study and optimization of the stretchability of the meanders in terms of humidity, thickness, and substrate. The results provide new insights for designing stretchable electronics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43830.     

Preparation and properties of epoxy‐modified tung oil waterborne insulation varnish

This work aimed to develop a novel epoxy‐modified tung oil waterborne insulation varnish with blocked hexamethylene diisocyanate as a curing agent. The Diels–Alder reaction between tung oil and maleic anhydride, and the ring‐opening esterification reaction of epoxy resin were confirmed. The conversion rate of epoxy was explored as a function of reaction time and temperature. The effects of epoxy resin content on the thermal stability, water absorption and insulation properties (insulation strength, volume resistivity, and surface resistivity) of films were investigated, and the resistances of films to salted water were evaluated. The increase in epoxy resin contents could improve the thermal stability and insulation properties of films, and decreased the water adsorption of films, but when the epoxy resin content reached 30% and above, the water solubility of resin became poor. After being immersed in 3.5 wt % NaCl solution, the electrical insulation strength of films were lower than that in dry state, and decreased as the immersed time prolonged. In particular, the electrical insulation strength loss of films increased significantly for epoxy resin content at 15% and below. Furthermore, the increase of epoxy resin content could improve the hardness and adhesion of films, but the flexibility of films became worse. On the basis of experimental, the epoxy resin content at 25% was appropriate to prepare waterborne epoxy‐modified tung oil resin. The resulting varnish may have potential as an immersing insulation varnish for the spindle of electric motor. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42755.     

Preparation of multifunctional thiol‐ and acrylate‐terminated polyurethane: A comparative study on their properties in UV curable coatings

The multifunctional thiol‐ and acrylate‐terminated polyurethane (PU) has been successfully prepared for using as the main resin in the UV curable coatings. The structure and molecule weight of prepared PUs were analyzed by fourier transformed infrared spectroscopy (FTIR) and gel permeation chromatography, respectively. The results showed that the different terminal multifunctional groups have been grafted onto the PU and their difference in molecule weight was significant. Used as the main resin in coatings, the curing kinetic and percentage conversion of the different UV curing coatings system were investigated by real‐time FTIR method, and the effects of terminal functional groups and photoinitiator on the final conversion percentage and conversion rate were also compared. It is observed that the thiol‐terminated PU had higher conversion speed and final conversion percentage due to the remarkable effect of mercapto groups on reducing oxygen inhibition during UV curing process. The shrinkage, viscosity, and adhesion of UV curable coatings with thiol‐ and acrylate‐terminated PUs were also investigated and compared, and the results indicated that the former exhibited lower shrinkage and higher adhesion performances than the latter, along with the lower viscosity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40740.     

Understanding the surface properties of polybenzoxazines: Interaction of polybenzoxazine model compounds with metal ions and water

The structure of polybenzoxazines (and their properties) is mainly defined by the existence of intra‐ and intermolecular hydrogen bonds. The effect of different substituents present in the phenolic ring of polybenzoxazines can modulate these intermolecular forces and the interaction with other materials, such as metals. To extend this knowledge, a series of structure‐controlled polybenzoxazines and polybenzoxazine model compounds have been synthesized. The interactions with different metal ions have been investigated using UV–vis and NMR analysis. Association constants have been estimated by UV–vis titration method and the effect of the presence of different substituents in the aromatic ring has been established. Water contact angles have also been measured. The different techniques give us information about the inner hydrogen bonding structure. Cyano group, present as substituent in polybenzoxazine compounds, acts as an additional coordination point towards metal ions and water. Our findings should allow modulating the adhesion and other surface properties of the benzoxazine‐derived polymers by playing with the properties of the substituents and their structure (phenoxy/phenolic). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44099.     

Indentation size effect of multiple orders of magnitude in polydimethylsiloxane

Indentation tests at indentation depths from 200 nm up to 100 μm were performed on polydimethylsiloxane (PDMS). The universal hardnesses in the elastomer were determined by microindentation and nanoindentation systems with Berkovich indenter tips and exhibited enormous increases of several orders of magnitude with decreasing indentation depth. Frank elasticity type molecular interactions were suggested as a rationale for the observed indentation size effect, which could have been related to material models with rotational gradients. A corresponding hardness model yielded good agreement with the experimental data. Other explanations for the indentation size effects in polymers in the literature are discussed in view of these experimentally determined and astonishing hardness increases in PDMS. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and properties of waterborne poly(urethane urea)s containing polydimethylsiloxane

To obtain flexible waterborne poly(urethane urea) (WBPU) coatings with functionalities such as shape recovery and water resistance, we synthesized a series of WBPUs by a prepolymer mixing process from hexamethylene diisocyanate, polyol, 2,2‐bis(hydroxymethyl) propionic acid, ethylenediamine, and triethylamine with polyol blends [hydroxyl‐terminated polydimethylsiloxane (PDMS) with a number‐average molecular weight of ≈ 550 and poly(tetramethylene oxide) glycol (PTMG) with a number‐average molecular weight of 650] of different molar ratios. The effects of the PDMS content in PDMS/PTMG on the dynamic thermal and mechanical properties, hardness, tensile properties, water resistance (water absorption, contact angle, and surface energy), and shape‐memory properties of WBPU films were investigated. As the molar percentage of PDMS in WBPUs increased, the storage modulus, tensile strength and modulus, elongation at break, hardness, and shape‐retention rate (30–15%) decreased; however, the water resistance and shape‐recovery rate (80–90%) increased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Crosslinking effect on polydimethylsiloxane elastic modulus measured by custom‐built compression instrument

A macroscopic compression test utilizing a simple custom‐built instrument was employed to measure polydimethylsiloxane (PDMS) elastic modulus. PDMS samples with varying crosslinking density were prepared with the elastomer base to the curing agent ratio ranging from 5 : 1 to 33 : 1. The PDMS network elastic modulus varied linearly with the amount of crosslinker, ranging from 0.57 MPa to 3.7 MPa for the samples tested. PDMS elastic modulus in MPa can be expressed as 20 MPa/PDMS base to curing agent ratio. This article describes a simple method for measuring elastic properties of soft polymeric materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41050.     

Effect of treatment pressure on structures and properties of PMIA fiber in supercritical carbon dioxide fluid

The effects of treatment pressure on the structures and properties of PMIA fiber were investigated by Scanning electron microscopy, Dynamic wetting measurements, Fourier transform infrared spectrometry, X‐ray diffraction, thermogravimetric analysis, and mechanical properties test technology in supercritical carbon dioxide. The results indicated that the surface morphology, the water contact angle, the interaction of macromolecules, the crystal structure, the thermal property, and tensile strength of PMIA fibers were changed during supercritical carbon dioxide treatment, particularly the surface morphology and the wettability of fiber changed the most obviously with the increase of treatment pressure. Furthermore, the thermal property and tensile strength of treated PMIA fiber sample were improved in comparison with those of untreated sample. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41756.     

Improving the properties of chemically damaged wool fabrics with carbohydrate polymers

Wool is a natural composite material consisting of keratin and keratin‐associated proteins as the key molecular components. During wool product processing, a variety of chemical and enzymatic reagents are used, the side‐effects of which can include the removal of the outside layers of the fiber (cuticle) and damage within the internal protein matrix of the fiber. This can reduce the mechanical strength and durability of wool fabrics. We report the use of neutral, cationic, and anionic carbohydrate polymers, namely 2‐hydroxyethyl cellulose, chitosan and alginate, as repair agents to improve the mechanical properties and morphology of wool fabrics damaged under harsh alkaline conditions. Tensile strength, peel adhesion, scanning electron micrographs, and fabric wettability evaluation reveal the cationic polymer, chitosan, to be most effective at remedying the effects of the alkaline treatment. The improved mechanical properties observed after chitosan treatment may offer viable remediation routes for adding value to processing‐damaged wool textiles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3105–3111, 2013     

Preparation,surface properties,and antibacterial activity of a poly(dimethyl siloxane) network containing a quaternary ammonium salt side chain

To obtain a copolymer network with low surface energy and antibacterial properties, a series of hydroxyl‐terminated poly(dimethyl siloxane)s (PDMSs) modified by a quaternary ammonium salt (QAS) side chain was synthesized via hydrolytic polycondensation and quaternization. The structures of the intermediate and final products were confirmed by Fourier transform infrared spectroscopy, ¹H‐NMR, and gel permeation chromatography. The results show that each step was successfully carried out, and objective products were obtained. The modified PDMSs were crosslinked with a commercial polyisocyanate to obtain cured QAS‐modified PDMS coatings. The target functional coatings exhibited excellent antibacterial performance with a low surface energy. When the molar content of QAS in PDMS was varied from 10 to 30%, the critical surface energy of the coatings remained in the range 24.05–26.88 mN/m; this indicated that the coatings had minimal adhesion with fouling according to the Baier curve. The bactericidal tests showed that the antibacterial activity was independent of the PDMS molecular weight but was closely correlated with the QAS content in PDMS. The bactericidal rate of the coatings to Escherichia coli and Staphylococcus aureus was higher than 97% when the molar content of QAS in PDMS was above 20%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41725.     

Influence of complexing treatment and epoxy resin coating on the properties of aramid fiber reinforced natural rubber

In this work, natural rubber/aramid fiber (NR/AF) composites were prepared with master batch method. AF was modified by using epoxy resin (EP) and accelerator 2‐ethyl‐4‐methylimidazole (2E4MZ) through surface coating on the basis of the complexing treatment with CaCl₂ solution. Hydroxyl‐terminated liquid isoprene rubber (LIR) was regarded as a compatibilizer between EP and NR. It is found that the crystallinity on AF surface is decreased by complexing reaction with CaCl₂ solution. Swelling and mechanical properties of the vulcanized composites, such as swelling degree, tensile and tear strength, tensile modulus at 300% elongation, are measured, and the tensile fracture morphology and dynamic mechanical analysis of the composites are investigated. The results show that the mechanical properties of composites with modified fibers are improved obviously and interfacial adhesion between matrix and the fiber is enhanced, especially for the AF coated with EP and imidazole. The best comprehensive mechanical properties of the composites are obtained with using CaCl₂‐EP/2E4MZ system when the ratio of m(EP)/m(AF) is 3%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42122.     

Preparation and properties of UV‐curable fluorinated polyurethane acrylates

A series of UV‐curable polyurethane acrylates (PUA0, FPUA3, FPUA6, FPUA 9 FPUA12, FPUA15, where the numbers indicate the wt % of perfluoroalkyl acrylate), were prepared from a reactive oligomer [4,4 ?‐dicyclohexymethanediisocyanate(H12MDI)/ poly(tetramethylene glycol)(PTMG)/2‐hydroxyethyl methacrylate (HEMA): 2/1/2 molar ratio, prepolymer:40 wt %] and diluents [methyl methacrylate (MMA, 20 wt %)/ isobornyl acrylate (IBOA, 40–25 wt %)/heptadecafluorodecyl methacrylate (PFA, 0–15 wt), total diluents: 60 wt %]. This study examined the effect of PFA/IBOA weight ratio on the properties of the UV‐curable polyurethane acrylates for antifouling coating materials. The as‐prepared UV‐curable coating material containing a 15 wt % PFA content in diluents (MMA/IBOA/PFA) form a heterogeneous mixture, indicating that a PFA content of approximately 15 wt % was beyond the limit of the dilution capacity of diluents for the oligomer. In the wavelength range of 400–800 nm, the UV‐cured PUA0 film sample was quite transparent (transmittance%: near 100%). On the other hand, the transmittance% of the FPUA film sample decreased markedly with increasing PFA content. XPS showed that the film‐air surface of the UV‐cured polyurethane acrylate film had a higher fluorine content than the film‐glass dish interface. As the PFA content increased from 0 to 12 wt %, the surface tension of the UV‐cured urethane acrylates decreased from 26.8 to 15.6 mN/m, whereas the water/methylene iodide contact angles of the film–air surface increased from 90.1/63.6° to 120.9/87.1°. These results suggest that the UV‐curable polyurethane acrylates containing a PFA content up to 12 wt % have strong potential as fouling‐release coating materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40603.     

Preparation and properties of fluorinated oligomer with tertiary amine structure in the UV curable coatings

A novel fluorinated oligomer with tertiary amine structure was synthesized by isophorone diisocyanate, 2‐hydroxyethyl acrylate, and fluorinated diol, which was prepared via Michael addition reaction between diethanolamine and dodecafluoroheptyl acrylate. The structure of fluorinated oligomer was confirmed by FTIR. The prepared fluorinated oligomer was added into the UV curable coatings, the influences of fluorinated oligomer on the cured degree and double bond conversion was analyzed by FTIR and gel content. The conversion ratio is increased when the fluorinated oligomer increased, which is due to the tertiary amine structure in the prepared product. The characteristics of UV cured films such as thermal properties, hydrophobicity, chemical resistance, mechanical properties, and hardness were characterized with the TGA, contact angle, and DMA. Results show that thermal stability, hydrophobicity, and chemical resistance are improved when fluorinated oligomer is introduced into the UV curable coatings. The DMA and hardness results indicated that the mechanical properties of UV cured films were improved and the flexibility decreased. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44387.     

Nanoindentation study of polydimethylsiloxane elastic modulus using Berkovich and flat punch tips

This article explores polydimethylsiloxane (PDMS) mechanical properties, and presents nanoindentation experiments with Berkovich and flat punch indenters. In the Berkovich tip quasi‐static nanoindentation test, there are pull‐in and pull‐off events observed during the initial tip contact, and when withdrawing from the surface, respectively. The pull‐in interaction needs to be accounted for to properly determine the initial contact point, and thus the accurate contact area. Once accounted for the pull‐in event, the Berkovich and flat punch tips quasi‐static nanoindentation tests give comparable results of about 1.5 MPa for the PDMS elastic modulus (5 : 1 elastomer base to the curing agent ratio). However, PDMS unloading stiffness is higher than the loading stiffness, and dynamic PDMS testing yields higher elastic modulus of about 3.6 MPa. While these results are comparable with the large strain macroscopic compression test results, the difference underscores the complexity of elastomer mechanical characterization and illustrates the discrepancies typical of the reported values. This article describes nanoindentation methods and critical aspects of interpreting results to assess PDMS mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41384.     

Soluble‐eggshell‐membrane‐protein‐modified porous silk fibroin scaffolds with enhanced cell adhesion and proliferation properties

In this study, a porous silk fibroin (SF) scaffold was modified with soluble eggshell membrane protein (SEP) with the aim of improving the cell affinity properties of the scaffold for tissue regeneration. The pore size and porosity of the prepared scaffold were in the ranges 200–300 μm and 85–90%, respectively. The existence of SEP on the scaffold surface and the structural and thermal stability were confirmed by energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The cell culture study indicated a significant improvement in the cell adhesion and proliferation of mesenchymal stem cells (MSCs) on the SF scaffold modified with SEP. The cytocompatibility of the SEP‐conjugated SF scaffold was confirmed by a 3‐(4,5‐dimethyltriazol‐2‐y1)‐2,5‐diphenyl tetrazolium assay. Thus, this study demonstrated that the biomimic properties of the scaffold could be enhanced by surface modification with SEP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40138.     

Production scale plasma modification of polypropylene baselayer for improved water management properties

Through its hydrophobic properties, polypropylene (PP) offers unique potential as a functional fiber for a wide range of applications, for example, in nonwovens for hygiene applications or as a baselayer in sports textiles. Current work is focused on the modification of PP presently used in baselayers for sports textiles to increase the hydrophilicity by use of a production scale plant for low pressure plasma treatment. Attention was directed toward an increase in hydrophilicity and time stability of the achieved modification during storage. Changes in the fabric were characterized by sorption of the cationic dye (methylene blue), water retention value, water transport properties, Fourier transform infrared spectroscopy and color measurement. The obtained results indicate an improved wettability and wicking. The extent of modification decreased with storage time and parallel yellowing of treated samples was observed. This indicates chemical rearrangement of the products initially formed on the fiber surface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41294.     

Effect of the concentration of the sizing agent on the carbon fibers surface and interface properties of its composites

The effect of the concentration of the sizing agent on performances of carbon fiber and carbon fiber composites has been investigated. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were applied to characterize carbon fiber surface topographies. At the same time, the single fiber strengths and Weibull distribution were also studied. The interlaminar shear strength and hygrothermal ageing test have been used to study the effect of fiber coatings on the interface of the composites. The analysis of the results shows that the sizing level is essential for improving the surface of carbon fibers and its composite performance. Different concentrations of the sizing agent have different contributions to the wetting performance of carbon fibers. Among the three concentrations of sizing agent studied (1 wt %, 1.5 wt %, and 2 wt %), the optimal sizing level is 1.5 wt %. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 125:425–432, 2011     

Preparation and properties of UV‐curable fluorinated polyurethane acrylates containing crosslinkable vinyl methacrylate for antifouling coatings

To obtain highly effective antifouling coatings, a series of UV‐curable polyurethane acrylates containing diluents [heptadecafluorodecyl methacrylate (PFA, 6 wt %)/isobornyl acrylate (IBOA, 34 wt %)/methyl methacrylate (MMA, 20‐5 wt %)/vinyl methacrylate (VMA, 0–15 wt %)] were prepared. This study examined the effect of bulky MMA (20‐5 wt %)/crosslinkable VMA (0–15 wt %) weight ratio on the properties of the UV‐curable polyurethane acrylates. The fluorine concentration in UV‐cured film surface increased with increasing VMA content up to 9 wt % and then decreased. The T_gα, transparency, elasticity, and mechanical properties of the UV‐cured film samples increased with increasing VMA content. The water/methylene iodide contact angles and surface tension of samples increased from 107/79 to 121/91° and decreased from 17.8 to 12.7 mN/m with increasing VMA content up to 9 wt % and then decreased/increased, respectively. From these results, it was found that the optimum VMA content was 9 wt % to obtain a high‐performance antifouling coating. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42168.