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1.
Regenerated cellulose nanoparticles (RCNs) are ideal materials for new biomass polymer composites industries. RCNs and composites of RCNs and water‐borne polyurethane (RCN/WPU) were prepared using a facile and environmentally friendly approach without the use of any harmful chemicals. The morphological, thermal, and mechanical properties of the RCN/WPU nanocomposite were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), rheometer, wide‐angle X‐ray diffraction, and enzymatic hydrolysis. RCNs exhibited low crystallinity upon regeneration with an NaOH‐based aqueous solution, and were identified by SEM and TEM to consist of the more thermodynamically stable cellulose form. TGA showed that the thermal stability of RCN/WPU nanocomposites was increased by the addition of RCNs. Finally, enzymatic hydrolysis using cellulase indicated that the biodegradability of RCN/WPU nanocomposites was also improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46633.  相似文献   

2.
Waterborne polyurethane (WPU) was prepared by the reaction of isophorone isocyanate (IPDI), polyether polyol (PTMG1000), dimethylol propionic acid (DMPA), and trimethylol propane (TMP) and 3-aminopropyltriethoxysilane (APTES) as coupling agent. The films of the WPU were prepared by casting emulsions on Teflon surfaces. The structure of the polyurethane (PU) was characterized by Fourier transform infrared spectrometer (FT-IR), thermogravimetry (TG), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). The mechanical properties and solvent absorption of the cast films were also measured quantificationally. FT-IR indicates that –NH2 of APTES reacted with –NCO of PU prepolymer. TG analysis indicates that APTES can improve thermal stability of PU. XRD and DSC show that crystallinity of PU decreased with the increase of w(APTES). It was found that greater mechanical properties of WPU were obtained when chemical networks were formed between PU and APTES. As the mass fraction of APTES increases from 0% to 10%, water absorption decreased from 17% to 8%, ethanol absorption decreased from 46% to 30%. The particle size increases with increase of w(APTES).  相似文献   

3.
Waterborne castor oil-recycled polyol based polyurethane-silica nanocomposite adhesives (WPU) with polymer matrix and silica nanoparticles chemically bonded have been successfully prepared through a sol-gel process. A series of waterborne polyurethane adhesives with hard segment contents from 71.3 to 74.5 wt%, were synthesized using an isophorone diisocyanate, 2-bis(hydroxymethyl) propionic acid, recycled castor oil-based as soft segments and (3-aminopropyl)triethoxysilane (APTES) as chain extender. The depolymerized oligoester obtained from glycolysis of poly(ethylene terephthalate) (PET) waste using triethylene glycol (TEG), was transesterified with castor oil (CO) which resulted in the formation of hydroxyl-functional polyester polyol, with hydroxyl value of 414 mgKOH g−1. The molecular structures and mass of glycolyzed PET oligoesters, castor oil-based polyol and castor oil-based polyurethane-silica nanocomposite adhesives were estimated by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The structure and properties of the resulting films were investigated by FTIR, wide angle X-ray diffraction measurement (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). TG analysis indicated that APTES can improve the thermal stability of WPU. XRD showed that the crystallinity of WPU decreased with the increase alkoxysilane content. The extent of crosslinking was investigated to show a dependence on silica concentration, which increased the glass transition temperature and particle size of polyurethane nanocomposites with increasing alkoxysilane content due to the condensation of the alkoxysilane groups. The hardness, adhesion and gloss quality of the polyurethane films were also determined considering the effect of APTES content, so this paper confirmed the suitability of using these castor oil-based waterborne polyurethane-silica nanocomposites as new adhesive materials with high performance coatings materials. The experimental results reveal that the APTES and the hard segment content play a key role in controlling the structure and properties of the PU cast films based on castor oil-recycled polyols.  相似文献   

4.
A novel graphene nanomaterial functionalized by octa(aminopropyl) polyhedral oligomeric silsesquioxane (OapPOSS) was synthesized and then confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, X‐ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM EDX), atomic force microscopy, and X‐ray diffraction. The obtained functionalized graphene (OapPOSS‐GO) was used to reinforce waterborne polyurethane (WPU) to obtain OapPOSS‐GO/WPU nanocomposites by in situ polymerization. The thermal, mechanical, and hydrophobic properties of nanocomposites as well as the dispersion behavior of OapPOSS‐GO in the polymer were investigated by TGA, a tensile testing machine, water contact angle tests, and field emission SEM, respectively. Compared with GO/WPU and OapPOSS/WPU composites, the strong interfacial interaction between OapPOSS‐GO and the WPU matrix facilitates a much better dispersion and load transfer from the WPU matrix to the OapPOSS‐GO. It was found that the tensile strength of the OapPOSS‐GO/WPU composite film with 0.20 wt % OapPOSS‐GO exhibited a 2.5‐fold increase in tensile strength, compared with neat WPU. Better thermal stability and hydrophobicity of nanocomposites were also achieved by the addition of OapPOSS‐GO. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44440.  相似文献   

5.
环氧改性蓖麻油基水性聚氨酯树脂的结构与性能   总被引:1,自引:0,他引:1  
用蓖麻油(CO)、聚四氢呋喃醚二醇(PTHF)、甲苯二异氰酸酯(TDI)、二羟甲基丙酸(DMPA)、环氧树脂(E—12)合成了水基聚氨酯树脂,去离子水乳化得到蓖麻油交联改性和环氧复合改性的水性聚氨酯乳液。通过拉伸、TG等测试手段表征了乳液的机械性能、热性能及耐化学品性能。结果显示:当蓖麻油的添加量为7.1%,环氧树脂含量为13.7%时,材料的机械性能达到最佳,环氧树脂的引入明显改善了材料的耐水性和耐温性,如耐水性达到120h无异常,耐沸水15min无变化。  相似文献   

6.
The investigation of aerogels made from cellulose nanofibers and poly(vinyl alcohol) (PVOH) as a polymeric binder is reported. Aerogels based on different nanocellulose types were studied to investigate the influence of the nanocellulose dimensions and their rigidity on the morphology and mechanical properties of the resulting aerogels. Thus, cellulose nanocrystals (CNCs) with low (10), medium (25), and high (80) aspect ratios, isolated from cotton, banana plants, and tunicates, respectively, microfibrillated cellulose (MFC) and microcrystalline cellulose (MCC) were dispersed in aqueous PVOH solutions and aerogels were prepared by freeze‐drying. In addition to the cellulose type, the PVOH‐ and the CNC‐concentration as well as the freeze‐drying conditions were varied, and the materials were optionally cross‐linked by an annealing step or the use of a chemical cross‐linker. The data reveal that at low PVOH content, rigid, high‐aspect ratio CNCs isolated from tunicates afford aerogels that show the least amount of shrinking upon freeze‐drying and display the best mechanical properties. However, with increasing concentration of PVOH or upon introduction of a chemical cross‐linker the differences between materials made from different nanocellulose types decrease. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41740.  相似文献   

7.
A series of waterborne polyurethane (WPU) dispersions modified with different contents of 3-aminopropyltriethoxysilane (APTES) were synthesized based on poly(1,6-hexyl 1,2-ethylcarbonate) diol (PHEC) and isophorone diisocyanate (IPDI), and the films were obtained by casting the dispersions on Teflon molds. Effects of APTES content on the particle size and viscosity of the dispersions were studied. The structure and properties of the resulting films were investigated by Fourier transform infrared spectroscopy, wide angle X-ray diffraction measurement, dynamic mechanical analysis, thermogravimetric analysis and mechanical testing. The experimental results showed that the incorporation of APTES played an important role in the enhancement of the water and toluene resistance and mechanical properties of the SPU films. Young's moduli and ultimate tensile strengths were improved from 8.0 to 451 MPa and 6.5–19 MPa respectively as the APTES content increased from 1 wt.% to 20 wt.%. The ability of scratch resistance was enhanced, when the content of APTES increased to 20 wt.%, the 3H pencil could not mar the surface. Moreover, the transmittance spectra indicated that the coatings showed high transparence.  相似文献   

8.
Waterborne polyurethane (WPU) dispersions with a high solid content and low viscosity were prepared successfully by a two‐step polymerization with isophorone diisocyanate, poly(propylene glycol), and dimethylol propionic acid as the main raw materials. The molar ratio of hard segments to soft segments was controlled to investigate its influence on the particle size, particle morphology, stability of dispersions, and final properties of the WPU films. Measurements including attenuated total reflectance/Fourier transform infrared spectroscopy, transmission electron microscopy, differential scanning calorimetry, thermogravimetric analysis, X‐ray diffraction, polarizing optical microscopy, and contact angle tests were used to characterize the bulk structures, phase separation, thermal stability, crystallinity, and wettability of the WPU dispersions. The results indicate that all of the WPU dispersions with a high solid content (ca. 40 wt %) and low viscosity (ca. 20–50 mPa s) displayed excellent stability. The prepared WPU dispersions with acetone contents of 5–7 wt % could be used directly as an ink binder without removing the acetone; this is beneficial to industrial applications of water‐based ink binders. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45406.  相似文献   

9.
Polyhydroxybutyrate (PHB) has been used in the biomedical field. However, the poor mechanical properties of PHB have limited its application. Here, electrospun fibrous nanocomposite mats reinforced with cellulose nanocrystals (CNCs) were fabricated by using PHB as polymeric matrix. The morphological, thermal, mechanical properties, as well as cytotoxicity were characterized. Increasing the concentration of CNCs caused a decrease in diameter of the electrospun fibers. Moreover, thermal analysis indicated that melting temperature of PHB/CNCs electrospun fibers were improved with the increased CNCs content. The addition of CNCs gradually enhanced the tensile strength till 8 wt % content followed by a gradual decrease at higher CNCs content (12–22 wt %) in tensile strength. The PHB/CNCs electrospun fibers were nontoxic to L‐929 and capable of supporting cell proliferation in all conditions. This study demonstrates that fibrous PHB/CNCs electrospun fibers are cytocompatible and potentially useful mechanical properties for biomedical application. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43273.  相似文献   

10.
Silver nanoparticles (AgNPs) were synthesized by a facile, mild and green method using dopamine as a reducing and stabilizing agent and were introduced to waterborne polyurethane (WPU) via an in situ emulsification method to prepare antibacterial nanocomposite films. The formation of AgNPs was characterized by UV–visible spectroscopy and XRD. The dispersion of AgNPs was confirmed by TEM and the thermal stability of WPU/Ag nanocomposites was confirmed by TGA. The results showed that AgNPs were uniformly dispersed in the WPU matrix. The introduction of AgNPs significantly improved the thermal stability of WPU films. With incorporation of 0.1 wt% AgNPs, a five-fold increase in the tensile strength was achieved without sacrificing the ultimate strain. The WPU/Ag nanocomposite films showed antibacterial activity against Escherichia coli and Staphylococcus aureus. © 2021 Society of Industrial Chemistry.  相似文献   

11.
This study aims to develop and characterize the nanocomposites using sulfur cross-linked carboxylated styrene-butadiene rubbers (S-xSBR) as the matrix and chitin nanocrystals (CNCs) as nanofillers. The composites’ morphology and properties were examined by light transmittances, fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), dynamic mechanical analysis (DMA), thermo gravimetric analyzer (TGA), and tensile properties determination. The addition of CNCs has slight effect on transparency of the composite films. FTIR data confirm the interfacial interactions between CNCs and S-xSBR via hydrogen bonds. CNCs are uniformly dispersed in the matrix from SEM result. The addition of CNCs can significantly improve the tensile strength and modulus both in static and dynamic states. The tensile modulus and tensile strength of S-xSBR/CNCs composites with the 4 wt.% CNCs is 62.5 % and 97.6 % higher than that of pure S-xSBR. The storage modulus, glass transition temperature, and the thermal stability of the composites are higher than those of the neat S-xSBR. The mechanical properties of the composite films are water-responsive, as the swollen samples exhibit obviously decreased strength and modulus. The greatest mechanical contrast is shown in the S-xSBR/CNCs composites with 2 wt.% CNCs loading whose tensile modulus decrease from 60.4 to 6.1 MPa after swelling equilibrium. The significant reinforcement effect of CNCs on S-xSBR is attributed to the unique structure of CNCs and the interfacial interactions in the composite.  相似文献   

12.
In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO) nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol) (PVA) and chitosan (Cs) blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses.  相似文献   

13.
Waterborne polyurethane (WPU) and casein (1 : 1 by weight) were blended at 90°C for 30 min, and then were crosslinked by adding 1–10 wt % ethanedial to prepare a series of sheets. Their structure and properties were characterized by using infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, dynamic mechanical analysis, and tensile testing. The results indicated that crosslinked blend sheets exhibited a certain degree of miscibility, and exhibited much higher tensile strength and water resistivity than did the WPU, casein, and the uncrosslinked blend from WPU and casein. When the ethanedial content was 2 wt %, the tensile strength and elongation at break of crosslinked sheets achieved 19.5 MPa and 148% in the dry state, and 5.0 MPa and 175% in the wet state, respectively. A 2 wt % content of ethanedial plays an important role in the enhancement of mechanical properties, thermal stability, and water resistivity of the blends of WPU and casein as a result of intermolecular crosslinking. This work provided a new protein plastic with good water resistivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 332–338, 2004  相似文献   

14.
Building blocks made from renewable sources attract increasing attention for the design of new polymer systems. Recently, in this particular context, cellulose nanocrystals (CNCs) have gained great interest in both academic research and industry, mainly on account of their ability to reinforce range of polymer matrices and afford nanocomposites with attractive mechanical properties. The limited thermal stability of conventionally produced cellulose nanocrystals (CNCs) has, however, so far limited the range of polymers that could be used as basis for melt‐processed CNC nanocomposites. We herein show that a commercially accessible nanocrystal source, a particular grade of microcrystalline cellulose (MCC), can easily be converted into thermally stable CNCs by ultrasonication in phosphoric acid. A scalable melt‐mixing process was used to produce nanocomposites of these CNCs with a thermoplastic polyurethane (TPU) elastomer. A significant improvement of the room temperature storage modulus from 40 MPa (neat polymer) to 120 MPa (10% w/w CNC) was observed. The introduction of CNCs not only increased the stiffness of the polymer matrix, but also improved the shape memory properties of the nanocomposite. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45033.  相似文献   

15.
以聚四氢呋喃二醇、异佛尔酮二异氰酸酯(IPDI)和2,2-二羟甲基丙酸(DMPA)为主要原料,羟乙基封端聚二甲基硅氧烷(SHG)为改性剂,采用自乳化法合成了阴离子型有机硅改性水性聚氨酯(WPU)。考察了异氰酸酯基与羟基的量之比(R值)、DMPA用量及SHG用量对WPU及其胶膜性能的影响;通过荧光显微镜分析了改性前后WPU的结构。结果表明:当异氰酸酯基与羟基的量之比为1.2、DMPA质量分数为4%、SHG质量分数为2%时,改性WPU的黏度低、稳定性好;其胶膜的吸水率从17%下降至6%,接触角从30.3°提高至75.7°,耐热性提高;微观形态更规整。  相似文献   

16.
In this work, poly(vinyl alcohol) (PVA) and cellulose nanocrystals (CNCs) were crosslinked using sodium tetraborate decahydrate (borax) to improve the mechanical and thermal properties of the neat PVA. The results showed that the CNCs affected the crystallization behavior of the crosslinked PVA. The crystallization temperature of the crosslinked PVA with CNCs increased considerably from ~152 to ~187 °C. The continuous improvement of the thermal stability was observed with the increasing content of CNCs in the crosslinked PVA films. Additionally, the strong interaction between the CNCs and PVA was theoretically estimated from the Young's modulus values of the composites. Thermodynamic mechanical testing revealed that the crosslinked PVA composite films with CNCs could bear higher loads at high temperature compared to the films without the CNCs. At 60 °C, 2.7 GPa was reported for the storage modulus of the crosslinked composites with 3 wt % of CNCs, twice as high as that for the crosslinked films without CNCs. Moreover, creep results were improved when CNCs were added in the crosslinked nanocomposites. The materials prepared in this work could broaden the opportunities for applications in a wide range of temperatures. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45710.  相似文献   

17.
With excellent biocompatibility and unique physiochemical properties, nanocelluloses including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are promising candidates for preparing biomedical hydrogels. CNCs and CNFs are different in morphology and surface charges. Herein, CNCs and two CNFs (CNFs-C, Carboxylated CNFs; CNFs-P, Phosphorylated CNFs) were synthesized and applied to fabricate hydrogels through metal crosslinking. Aluminum crosslinking was found to be the best choice for enhancing the strength. This study systematically compared the morphologies, storage modulus, loss factor, continuous shear ramp, self-healing, swelling, in vitro degradation and injectable properties of the fabricated hydrogels. Further, a radar chart is summarized as guidelines to direct the rational selection to meet the specific requirements of further biomedical applications. At the same nanocellulose concentration and after Al3+ crosslinking, CNCs hydrogels had strong water holding capacity twice as much as that of CNFs hydrogels. While CNFs hydrogels showed higher hardness and stronger resistance to degradation than that of CNCs. These results provide detailed insights into nanocellulose hydrogels, making it possible to use these guidelines to select hydrogels for desired performance.  相似文献   

18.
Although tremendous efforts have been dedicated to developing environmentally friendly bio-based waterborne polyurethane (WPU) dispersions from vegetable oil, the fabrication of WPU dispersions solely derived from vegetable oil-based polyol with excellent comprehensive properties is still challenging. In the present work, novel bio-based WPU dispersions derived from castor oil and soy polyol is successfully modified by phosphorus-nitrogen chain extender [bis(2-hydroxyethyl)amino]-methyl-phosphonic acid dimethyl ester (BH). The structure and properties of the dispersions and films are characterized systematically by Fourier transform infrared spectroscopy, thermogravimetric analysis , mechanical test, and limiting oxygen index (LOI), etc. The results indicate that bio-based WPU films display moderate mechanical performance by adjusting BH content, and the WPU film containing 100% BH with 47.8% biobased content has a tensile strength of 8 MPa and the highest Young's modulus of 62.3 MPa. The incorporation of BH can increase the production of char residue. The flame retardancy of WPU films increase gradually with the BH molar content, and the LOI value of the WPU100 with 1.53 wt% phosphorus content can reach as high as 28.1%. This work may provide a new approach to develop high biobased content, eco-friendly, flame retardant WPU for application in the surface coating industry.  相似文献   

19.
用聚酯/碱溶性聚酯(PET/COPET)海岛纤维无纺布含浸含磷自阻燃的水性聚氨酯(WPU)浆料,通过干法凝固、碱减量和后整理等工艺制备阻燃型聚酯超细纤维/水性聚氨酯(PETMF/WPU)复合材料。分析并探讨不同固含量含磷自阻燃的WPU浆料对PETMF/WPU复合材料的阻燃性能和力学性能的影响。采用锥形量热仪、极限氧指数和垂直燃烧对其阻燃性能进行表征;采用电子扫描显微镜对其微观结构进行表征;采用TGA对其热稳定性进行表征。结果表明:当固含量达到35wt%时,PETMF/WPU复合材料的LOI值达到31.7%,垂直燃烧达到V-0级,在燃烧过程中能够自熄且无熔滴产生,力学性能仍能满足行业标准,使用含磷自阻燃原料减少了燃烧过程中有害气体的释放。  相似文献   

20.
A series of multiple cross-linking ultraviolet (UV) curable waterborne polyurethane dispersions (UV-PUDs) were synthesized by modification of diglycidyl ether of bisphenol-A-based epoxy resin (E51) through ring-opening by 3-aminpropyltriethoxysilane (APTES). Initially, APTES-E51 was synthesized using APTES to open the epoxy groups of E51. Then, APTES-E51 was incorporated into the chains of polyurethane, and multiple cross-linking UV-PUDs were produced. The chemical structures were confirmed by the Fourier-transform infrared spectroscopy (FTIR) and the effect of the APTES-E51 content on the UV-PUDs properties was investigated. The average particle size of UV-PUDs was determined by dynamic light scattering (DLS). The result showed that the average particle size increased with increasing APTES-E51 content and the stability of the UV-PUD storage diminished when the content of APTES-E51 was 10.0%. After modification by APTES-E51, the water absorption of the UV-cured films decreased and the water contact angle (CA) increased significantly. Thermogravimetry analysis (TGA) of the UV-cured films illustrated that APTES-E51 modified UV-curable waterborne polyurethane could exhibit good thermal stability. In addition, mechanical property of the cured films showed that the incorporation of APTES-E51 also improved tensile strength of the cured films. We can obtain good storage stability, satisfied water resistance, and high thermal stability and tensile strength when the APTES-E51 content of the UV-PUD was 9.1%.  相似文献   

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