热塑性聚氨酯复合材料薄膜的制备及其性能研究

利用纵向氧化切割多层碳纳米管（MWCNTs）制得氧化石墨烯纳米带碳纳米管（GONRs-CNTs）2种维度纳米杂化材料,用异氰酸苯酯对GONRs(67 %)-CNTs纳米杂化体进行表面化学修饰制得功能化GONRs(67 %)-CNTs（pGONRs-CNTs,GONRs质量分数为67 %）,探究了pGONRs-CNTs对热塑性聚氨酯（TPU）薄膜阻隔、力学和降解性能的影响。结果表明,改性后所得pGONRs-CNTs杂化体表面变得模糊而粗糙,亲油性得到明显提高,有利于其在聚合物基体中实现均匀稳固分布。当pGONRs-CNTs含量为0.5 %（质量分数,下同）时,TPU/pGONRs-CNTs材料相比纯TPU材料的氧气透过率（OTR）低63.08 %,拉伸强度高46.55 %,其对应的阻透性能与力学性能均有较大程度提高;而且,由于pGONRs-CNTs物质的使用,使TPU材料的使用寿命延长。     

Mechanical,electrical and thermal performance of hybrid polyethylene-graphene nanoplatelets-polypyrrole composites: a comparative analysis of 3D printed and compression molded samples

ABSTRACT

The paper focuses on the investigation of the 3D printing of multi-functional composites using graphene nanoplatelets (GNP), polypyrrole (PPY) and linear low-density polyethylene (LLDPE). A holistic approach was performed and characterization methods to assess the properties of 3D printed composites and compared with those of compression molded composites and neat LLDPE to understand the factors affecting their performance. It has been noted that the 3D printed composites have superior mechanical and electrical properties than neat LLDPE, but slightly lower compared to those of compression molded composites having high packing density of fillers. The nominal increases were 13.2% (tensile strength), 31.9% (flexural strength), 29.4% (flexural modulus) and 24.7% (storage modulus).     

Effect on thermal,mechanical, and biodegradable properties of plasma-treated fish scale powder/linear low-density polyethylene polymer composite films

In the present work, we report the effect of low-temperature plasma treatment on thermal, mechanical, and biodegradable properties of polymer composite blown films prepared from carp fish scale powder (CFSP) and linear low-density polyethylene (LLDPE). The CFSP was melt compounded with LLDPE using a filament extruder to prepare 1, 2, and 3 wt.% of CFSP in LLDPE polymer composite filaments. These filaments were further pelletized and extruded into blown films. The blown films extruded with 1, 2, and 3 wt.% of CFSP in LLDPE were tested for thermal and mechanical properties. It was observed that the tensile strength decreased with the increased loading content of CFSP, and 1% CFSP/LLDPE exhibited the highest tensile strength. To study the effect of low-temperature plasma treatment, 1% CFSP/LLDP polymer composite with high tensile strength was plasma treated with O₂ and SF₆ gas before blow film extrusion. The 1% CFSP/LLDPE/SF₆-extruded blown films showed increased thermal decomposition, crystallinity, tensile strength, and modulus. This may be due to the effect of crosslinking by the plasma treatment. The maximum thermal decomposition rate, crystallinity %, tensile strength, and modulus obtained for 1% CFSP/LLDPE/SF₆ film were 500.02°C, 35.79, 6.32 MPa, and 0.023 GPa, respectively. Furthermore, the biodegradability study on CFSP/LLDPE films buried in natural soil for 90 days was analyzed using x-ray fluorescence. The study showed an increase in phosphorus and calcium mass percent in the soil. This is due to the decomposition of the hydroxyapatite present in the CFSP/LLDPE biocomposite.     

Polyethylene with MoS2 nanoparticles toward antibacterial active packaging

Molybdenum disulfide (MoS₂) nanoparticles, obtained from liquid phase exfoliation in the presence of chitosan, were melt mixed with a linear low-density polyethylene (LLDPE) matrix to produce novel antimicrobial active packaging materials. The LLDPE/MoS₂ composites presented exfoliated nanoparticles forming aggregates that are well dispersed in the polymer matrix. These 2D-layered MoS₂ nanoparticles at concentrations of 0.5, 1.0, and 3.0 wt% rendered several functionalities to the LLDPE, as for example an antimicrobial behavior against Salmonella typhi and Listeria monocytogenes bacteria that can be explained not only by the photoactivity of the filler but also by changes in the composite surface. For instance, the composites presented a reduction in the water contact angle (i.e., an increased hydrophilicity) and relevant changes in the surface topography (i.e., reduced roughness) as compared with pure LLDPE. Regarding the barrier properties, while MoS₂ dramatically increased the water vapor permeation (WVP) of the polymer matrix, until 15 times for composite with 3.0 wt% of filler, the oxygen permeation decreased around 25%. All these novel functionalities in the nanocomposites were obtained without significantly affecting the tensile mechanical properties of the pure LLDPE matrix. These results show that MoS₂ is a promising filler for the development of antibacterial active packaging films with behaviors as similar as other 2D-layered fillers such as graphene derivatives.     

Improvement of mechanical,thermal and tribological properties of (3-aminopropyl) triethoxysilane-modified graphene/polyimide nanocomposites by in situ polymerisation

To elucidate the improvement and the principle of graphene modification on the polyimide (PI), (3-aminopropyl) triethoxysilane-modified graphene (PMG), was designed and prepared by anchoring the (3-aminopropyl) triethoxysilane (APTS) chain on the graphene sheet surface, and used to synthesise PI composites by in situ polymerisation. The unique surface modification significantly improved the compatibility and dispersion of graphene in the PI matrix. Tensile strength and Young’s modulus of 1.0PMG/PI was 109.45?MPa and 1.73?GPa, which increased by 54.26 and 86.02% from neat PI, respectively. The tribological properties and mechanism were also discussed. The friction coefficient and wear rate of 1.0PMG/PI (0.287, 2.291×10^?5mm³?Nm^?1) decreased by 47.53% and 35.06%, respectively. This improvement of the tribological properties was mainly caused by the cooperative interaction of the improved mechanical and thermal properties of the composites and the high self-lubricity of modified graphene.     

Thermomechanical and corrosion inhibition properties of graphene/epoxy ester–siloxane–urea hybrid polymer nanocomposites

The effect of graphene on the corrosion inhibition properties of a hybrid epoxy–ester–siloxane–urea polymer was investigated. The weight fraction of graphene was varied from 1 to 2 wt%. Direct current polarization (DCP) and electrochemical impedance spectroscopic (EIS) techniques were used to measure the polarization and coating resistance of the coated aluminum alloy substrate. The grapheme/hybrid polymer composite coatings showed much higher corrosion inhibition property when compared to the neat hybrid polymer coating. An increase in glass transition temperature and rubbery region modulus was also observed for composites containing 1–2 wt.% of graphene. A direct correlation between the rubbery plateau modulus of free standing composite thin films and corrosion resistance of the composite coatings was made, indicating that the corrosion protection mechanism is due to restriction of the polymer chain motion by graphene which causes a decrease in coating permeability.     

Furfuryl alcohol functionalized graphene nanosheets for synthesis of high carbon yield novolak composites

Graphene oxide and furfuryl alcohol modified graphene nanosheets (G‐FA) were used to prepare graphene/novolak composites. Effect of graphene compatibilization on the properties of the composites especially carbon yield value is evaluated. Both types of graphene nanosheets were dispersed uniquely in the novolak matrix as proved by X‐ray diffraction analysis. However, modification of graphene sheets by furfuryl alcohol results in more improved dispersions. Thermogravimetric analysis confirms the elevated thermal stability of the nanocomposites in comparison with the neat novolak. In addition, G‐FA containing composites have higher carbon yield values. A shift in the wave number of characteristic bonds of graphene after oxidation and modification with furfuryl alcohol, O? H, C?O, and C? O bonds, are seen in the Fourier transform infrared spectroscopy spectra. Raman results and scanning electron microscopy images show that graphene nanosheets reduced in size and wrinkled by oxidation and functionalization. Transmission electron microscopy image of the composite with 0.2 wt % of G‐FA reveals the presence of nanosheets with curvature. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40273.     

Preparation and Tribological Properties of Polyamide 11/Graphene Coatings

Polyamide 11/graphene coatings were prepared through a spraying method with as-prepared organophilic graphene. The tribological results showed that the wear life of composite coatings was obviously higher than that of neat Polyamide 11 coating; however, the values of friction coefficients had hardly changed. The optimal content of graphene in the range of our experiments was 0.4 wt%, and the wear life of the composite coating increased by 460%–880% compared with that of pristine Polyamide 11 coating. The morphology of worn surface for both pristine Polyamide 11 and the composites coatings was studied, and the wear mechanisms were discussed.     

Preparation and characterization of epoxy nanocomposites containing surface‐modified graphene oxide

A three‐step grafting procedure has been used to graft the epoxy monomers (DER332) and the curing agents (diamino diphenyl methane (DDM), onto graphene oxide (GO) surface. The surface modification of GO has been performed by grafting of Jeffamine D‐2000, followed with subsequent grafting of DER332 and DDM, respectively. Fourier transform spectroscopy and thermogravimetric analysis indicate successful surface modification. The resulting modified GO, that is, (DED)‐GO, can be well dispersed in the epoxy monomers. The epoxy nanocomposites containing different GO contents can then be prepared through curing processes. The dispersion of GO in the nanocomposites is characterized by transmission electron microscopy. It is found that the tensile strength and elongation at break of epoxy nanocomposite with only 0.2 wt % DED‐GO are increased by 30 and 16% as compared with the neat epoxy resin, respectively. Dynamic mechanical analysis results show that 62% increase in storage modulus and 26°C enhancement in the glass transition temperature of the nanocomposite have been achieved with the incorporation of only 0.2 wt % of DED‐GO into the epoxy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40236.     

Soy‐filled polyethylene fibers for modified surface and hydrophilic characteristics

By adding soy flour (soy) to linear low‐density polyethylene (LLDPE), soy‐PE fibers with enhanced hydrophilic characteristics were developed. Blends containing only soy and LLDPE had limited draw‐down, and the resulting thick fibers showed poor mechanical properties. When monoglyceride was added as a compatibilizer, thin fibers with good properties could be successfully spun due to improved dispersion of soy agglomerates in the LLDPE melt. Fibers spun from a blend containing 23/7/70 wt % of soy‐monoglyceride‐LLDPE displayed a tensile modulus and strength of 615 ± 38 and 57 ± 8 MPa, respectively. At 30% less synthetic content, these fibers still displayed mechanical properties generally comparable to those of base polyethylene fibers. Contact angle measurements showed that the soy‐based fibers had a hydrophilic surface (contact angle of 33° ± 4°). Moisture absorption studies confirmed that soy‐PE fibers gained about 20 wt % moisture in 1 h, whereas neat LLDPE fibers did not absorb any significant amount (LLDPE is hydrophobic). This hydrophilic behavior of soy‐PE fibers mimics that of natural fibers. Presence small soy agglomerates on the fiber surface also provides a textured surface and a desired tactile feel to the soy‐PE fibers, which coupled with hydrophilic behavior indicates their potential use in disposable nonwovens. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46609.     

Enhanced mechanical and thermal properties of polyurethane/functionalised graphene oxide composites by in situ polymerisation

ABSTRACT

Isocyanate-functionalised graphene (iGO) was prepared and incorporated into a thermoplastic polyurethane via an in situ polymerisation. Firstly, graphene oxide was successfully modified using a mixture of isocyanate- and diisocyanate-containing compounds, leading to the formation of good dispersions of resulting functional graphene oxide in organic solvents, such as N,N-dimethylacetamide and N,N-dimethylformamide. The addition of iGO into polyurethane matrix improved both mechanical and thermal properties in the polyurethane/iGO composites relative to neat polyurethane. An addition of only 0.03?wt-% of functionalised graphene into the polyurethane increased Young’s modulus by 1.4 times and tensile strength by two times. Meanwhile, the elongation at break was similar to that of the neat polymer. In addition, dynamic mechanical analysis also confirmed the improvement in storage modulus of the polymer composites especially at high-temperature range. We believe that the developed modification approach for graphene oxide and polyurethane/graphene composites presented herein could be useful in polymer/graphene composite development.     

Graphene/polyethylene nanocomposites: Effect of polyethylene functionalization and blending methods

Since its recent successful isolation, graphene has attracted an enormous amount of scientific interest due to its exceptional physical properties. Graphene incorporation can improve electrical and mechanical properties of polymers including polyethylene (PE). However, the hydrophobic nature and low polarity of PE have made effective dispersion of nano-fillers difficult without compatibilization. Graphene was derived from graphite oxide (GO) via rapid thermal exfoliation and reduction. This thermally reduced graphene oxide (TRG) was blended via melt and solvent blending with linear low density PE (LLDPE) and its functionalized analogs (amine, nitrile and isocyanate) produced using a ring-opening metathesis polymerization (ROMP) strategy. TRG was well exfoliated in functionalized LLDPE while phase separated morphology was observed in the un-modified LLDPE. Transmission electron micrographs showed that solvent based blending more effectively dispersed these exfoliated carbon sheets than did melt compounding. Tensile modulus was higher for composites with functionalized polyethylenes when solvent blending was used. However, at less than 3 wt.% of TRG, electrical conductivity of the un-modified LLDPE was higher than that of the functionalized ones. This may be due to phase segregation between graphene and PE, and electrical percolation within the continuous filler-rich phase.     

A novel phytic acid based flame retardant to improve flame retardancy,hydrophobicity and mechanical properties of linear low-density polyethylene

Exploiting high phosphorus content of phytic acid, it was grafted onto magnesium hydroxide (MH) by neutralization reaction to obtain MGPA, a flame retardant. A current study investigated the effect of MGPA on hydrophobicity, flame retardancy, and mechanical properties of MGPA-linear low-density polyethylene (LLDPE) composites. The LLDPE composite with 50 parts of MGPA has the better flame retardancy and thermal stability with a limiting oxygen index of 23.3%, which is higher than that of neat LLDPE (17%). In addition, MGPA could effectively promoted LLDPE to form a continuous and compact char residue during combustion, which reduce the peak of heat release rate and total smoke production value of LLDPE composite by 70% and 36%, respectively, and the char residue rate increase to 67.5%. Furthermore, the maximum of loss-rate showed by LLDPE composite with MGPA reduce to 1.25%/min while the value of LLDPE composite with MH is 1.8%/min. Meanwhile, the LLDPE composite with MGPA show remarkable elongation at break and hydrophobicity, which are 398% and 99°, respectively. In addition, this study presents a substantial flame retardancy and interfacial compatibility of MGPA for extending the applications of flame-retardant LLDPE composites.     

Linear low‐density polyethylene/poly(ethylene terephthalate) blends compatibilization prepared by an eccentric rotor extruder: A morphology,mechanical, thermal,and rheological study

In this study, various poly(ethylene terephthalate) (PET) and linear low‐density polyethylene (LLDPE) with maleic anhydride‐grafted LLDPE (LLDPE‐g‐MAH) compatibilizer were melt blended under an elongational flow. A novel extrusion device, eccentric rotor extruder (ERE), was developed to supply such flow during the process. Including morphology, mechanical properties, melting behavior, and rheological behavior were studied. The morphological study showed that the compatibility between LLDPE and PET was greatly improved with LLDPE loading up to 80 wt %. Mechanical tests indicated that LLDPE could toughen PET to some extent. Moreover, a comparison of samples prepared between ERE and conventional extruder was made and demonstrated the sample prepared by ERE can exhibit better mechanical properties. Differential scanning calorimetry results revealed that PET can promote the crystallinity of LLDPE. Rheological behavior indicated that the complex viscosity of the blends exhibited strong shear thinning phenomenon with increasing LLDPE content, particularly in high‐frequency range blend with the LLDPE weight ratio of 80 wt % was more sensitivity to shear rate than neat LLDPE. The G′‐G″ curves of the blends also revealed that the microstructure of the blends changed significantly with the addition of LLDPE which was consistent with the scanning electron micrographs that PET particles became smaller and distributed more uniform with increasing LLDPE content. Furthermore, the blends showed similar stress relaxation mechanism with adding LLDPE content from 60 to 100 wt %. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46489.     

Calendered linear low‐density polyethylene consolidated meat and bone meal composites

Bioplastics produced from meat and bone meal (MBM) suffer from rapid and drastic mechanical property deterioration because of their hydrophilic nature. This study investigates mechanical and water stability of composites produced from introduction of a minor component of a synthetic polyethylene as a binder phase to consolidate MBM. The milled and sieved MBM was compounded with 5–60 wt % linear low‐density polyethylene (LLDPE) and formed into composite sheets by calendering, which is an industrially relevant process. Results indicated that a minimum of 15 wt % LLDPE content was required to form a nominally continuous binder phase that allowed for good processability and environment stability of the composites. As expected, the water vapor permeability (WVP) and water absorption characteristics of the composites were intermediate between those of MBM and LLDPE. Sheets containing 15 wt % LLDPE absorbed up to 35 wt % water. Composites tested after being soaked in water showed an initial decrease in TS of about 30% for the first hour but then remained fairly unchanged in the next 72 hours, confirming their moderate environment stability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41145.     

THE EFFECT OF ANHYDRIDE MODIFICATION OF SAGO STARCH ON THE TENSILE AND WATER ABSORPTION PROPERTIES OF SAGO-FILLED LINEAR LOW-DENSITY POLYETHYLENE (LLDPE)

Sago starch was chemically modified through esterification using 2-dodecen-1-yl succinic anhydride (DSA) and propionic anhydride (PA) and three different solvents: [N,N dimethylformamide (DMF), triethylamine (TEA), and toluene (TOU)]. The effect of reaction times and temperatures on the modification was investigated. Evidence of anhydride modification was established by the weight percent gain (WPG) and was further confirmed by FTIR. The DSA–DMF and PA–DMF system, when subjected to the reaction condition of 120°C for 5 h, resulted in the highest WPG. Starch modified with 2-dodecen-1-yl succinic anhydride (MS) and propionic anhydride (MS2) was employed in preparation of composites. Samples of composites containing blends of MS/LLDPE and MS2/LLDPE with four different loadings of fillers (10, 25, 40 and 50% based on composite weight) were prepared. With unmodified ST/LLDPE, as the starch content increased, tensile modulus and water absorption increased—but tensile strength and elongation at break showed the opposite effect. With modification, the MS/LLDPE and MS2/LLDPE blends showed improved mechanical and water absorption properties as compared to ST/LLDPE.     

Preparation and Properties of a Reactive Type Nonionic Surfactant Grafted Linear Low Density Polyethylene

Summary A reactive type nonionic surfactant, monostearic acid monomaleic acid glycerol diester (MMGD) was synthesized in our laboratory. Grafting-copolymerization of linear low density polyethylene (LLDPE) with MMGD was carried out by using β ray irradiation in air in a twin-screw extruder. Evidence of the grafting of MMGD as well as its extent was determined by Fourier-transformed infrared (FT-IR) spectroscopy. The effects of monomer concentration, reaction temperature and screw run speed on degree of grafting were studied systematically. The thermal behavior of LLDPE-g-MMGD was investigated by using differential scanning calorimety (DSC). Compared with neat LLDPE, the crystallization temperature (T_c) of LLDPE-g-MMGD increased about 3 °C, and the melting enthalpy (ΔH_m) decreased with increase of MMGD content. It showed that the grafted MMGD monomer onto LLDPE acted as a nucleating agent. The tensile properties and light transmission of blown films were determined. Comparing with neat LLDPE film, no obvious changes could be found for the tensile strength, elongation at break and right angle tearing strength of LLDPE-g-MMGD film. The wettability is expressed by the water contact angle. With an increasing percentage of MMGD, the contact angles of water on film surface of LLDPE-g-MMGD decrease monotonically. Accelerated dripping property of film samples was investigated. The dripping duration of LLDPE-g-MMGD film and commercial antifog dripping film at 60 °C were 52 days and 17 days, respectively.     

Characterization of linear low-density polyethylene and halloysite nanotube (LLDPE/HNT) composites based on two-roll calendering melt fabrication

In preparation of polymer nanocomposites, achieving good mixing and uniform distribution of nanofillers is highly desired for property enhancement. Polyethylene (PE) and its nanocomposite with halloysite nanotubes (HNTs) possesses a myriad of potentials for advanced engineering properties. A high nanoparticle loading is preferred to capitalize the nano-reinforcement, thermal, and barrier properties. The capability of a two-roll calendaring machine to disperse HNT particles into a linear low-density polyethylene (LLDPE) matrix at elevated processing temperatures was assessed. Morphological, thermal, mechanical, and rheological behavior of prepared nanocomposites were characterized. A homogeneous distribution of HNTs in concentrations up to 5 wt.% was evidenced by SEM analysis. TGA showed the 10 wt.% composite exhibited an overall outstanding thermal stability. DSC analysis revealed the 30 wt.% sample has the highest T_m and T_c, and the %crystallinity did not change much due to HNT incorporation for all samples. DMA showed the storage and loss moduli increased with increase in HNT loadings. The effect of loading HNTs into the LLDPE matrix on T_g was minimal, implying that LLDPE and HNTs are quite compatible. The results demonstrated that the two-roll mill fabrication method can efficiently keep HNT particles unagglomerated and disperse them evenly into the LLDPE matrix.     

Flame retarding effect of graphite in rotationally molded polyethylene/graphite composites

Linear low‐density polyethylene (LLDPE) compounds containing 10 wt % graphite fillers were rotationally molded into flat sheets. Flame retardancy was studied using cone calorimeter tests conducted at a radiative heat flux of 35 kW/m². Only the expandable graphite, an established flame retardant for polyethylene, significantly reduced the peak heat release rate. Compared with the neat polyethylene, it was easier to ignite the LLDPE composites containing carbon black, expandable graphite, and exfoliated graphite. However, rather unexpectedly, the inclusion of flake graphite increased the time to ignition by up to 80%. Simulations conducted with the ThermaKin numerical pyrolysis software suggest that increased reflectivity was mainly responsible for this effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41472.     

Nano/Micro Particle Hybrid Composites for Scratch and Abrasion Resistant Polyacrylate Coatings

Summary: UV curable acrylate formulations with a high content of fumed, nano‐sized silica were prepared to improve their application for abrasion and scratch resistant top coats. Grafting of trialkoxysilanes onto the surface of nanoparticles facilitated their embedding in the formulation and alleviated the effect of undesired increase in viscosity and dilatancy. Modified nanoparticles were obtained from several organosilanes and characterized by a multitechnique approach. To avoid problems during redispersion, in situ modification of nano‐sized silica was performed using the liquid acrylate formulation as a diluting and deagglomerating agent. These nanocomposite materials exhibit markedly improved properties as compared to neat acrylate coatings, e.g. heat, scratch, and abrasion resistance. However, a much better abrasion resistance was obtained for coatings containing both silica nanoparticles and corundum microparticles. By using various grades of corundum, a synergetic effect of nano/micro hybrid composite materials has been studied for parquet and flooring applications.

Pictures of neat polyacrylate coating (on the left) and nano/micro hybrid composite material (18 wt.‐% silica +15 wt.‐% corundum) on parquet substrate after Taber Abraser Test.