Synthesis and Characterization of Linear Low Density Polyethylene Grafted Glycerol Monolauric Acid Monoitaconic Acid Diester

A reactive type dripping agent, glycerol monolauric acid monoitaconic acid diester (GLID) was synthesized in our laboratory. Grafting-copolymerization of linear low density polyethylene (LLDPE) with GLID was carried out by using β-ray irradiation in air in a twin-screw extruder. FT-IR was used to characterize the formation of grafting copolymer and evaluate their degree of grafting. The effects of monomer concentration, reaction temperature and screw run speed on degree of grafting were studied systematically. Crystallization rates of grafted LLDPE were faster than that of plain LLDPE at a given crystallization temperature. 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-GLID film. Acceleration dripping property of film samples was investigated. The dripping duration of LLDPE-g-GLID film and commercial antifog dripping film at 60° C were 69 days and 17 days, respectively.     

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.     

Preparation and physical properties of LLDPE grafted with novel nonionic surfactants

Copolymers of linear low‐density polyethylene (LLDPE) grafted with two novel nonionic surfactants, acrylic glycerol monostearate ester (AGMS) and acrylic polyoxyethylenesorbitan monooleate ester (ATWEEN80), containing hydrophilic and hydrophobic groups and 1‐olefin double bond were prepared by using a plasticorder at 190°C. To evaluate the grafting degree, two different approaches based on ¹H‐NMR data were proposed, and FTIR calibration was showed to validate these methods. The rheological response of the molten polymers, determined under dynamic shear flow at small‐amplitude oscillations, indicated that crosslinking formation of the chains could be decreased with increasing the monomer concentration. Their thermal behavior was studied by DSC and polarization microscope (PLM): The crystallization temperature (T_C) of grafted LLDPE shifted to higher temperature compared with neat LLDPE because the grafted chains acted as nucleating agents. Water and glycerol were used to calculate the surface free energy of grafted LLDPE films. The results indicated that the novel polyoxyethylene surfactant ATWEEN80 could greatly improve the hydrophilicity of LLDPE and the surface free energy varied from 33 mN/m of neat LLDPE to 106 mN/m of the grafted LLDPE film. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surface modification of linear low‐density polyethylene film by amphiphilic graft copolymers based on poly(higher α‐olefin)‐graft‐poly(ethylene glycol)

In this article, a series of amphiphilic graft copolymers, namely poly(higher α‐olefin‐co‐para‐methylstyrene)‐graft‐poly(ethylene glycol), and poly(higher α‐olefin‐co‐acrylic acid)‐graft‐poly(ethylene glycol) was used as modifying agent to increase the wettability of the surface of linear low‐density polyethylene (LLDPE) film. The wettability of the surface of LLDPE film could be increased effectively by spin coating of the amphiphilic graft copolymers onto the surface of LLDPE film. The higher the content of poly(ethylene glycol) (PEG) segments, the lower the water contact angle was. The water contact angle of modified LLDPE films was reduced as low as 25°. However, the adhesion between the amphiphilic graft copolymer and LLDPE film was poor. To solve this problem, the modified LLDPE films coated by the amphiphilic graft copolymers were annealed at 110° for 12 h. During the period of annealing, heating made polymer chain move and rearrange quickly. When the film was cooled down, the alkyl group of higher α‐olefin units and LLDPE began to entangle and crystallize. Driven by crystallization, the PEG segments rearranged and enriched in the interface between the amphiphilic graft copolymer and air. By this surface modification method, the amphiphilic graft copolymer was fixed on the surface of LLDPE film. And the water contact angle was further reduced as low as 14.8°. The experimental results of this article demonstrate the potential pathway to provide an effective and durable anti‐fog LLDPE film. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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.     

Performance elevation of linear low‐density polyethylene highly loaded with aluminum hydroxide by the grafting of methacrylic acid to the matrix

The mechanical and electric performances of linear low‐density polyethylene (LLDPE) highly loaded with aluminum hydroxide (Al(OH)₃) by the grafting of methacrylic acid (MAA) to the LLDPE matrix were studied. The results of Fourier transform infrared spectroscopy showed that the grafting reaction occurred by melt grafting. Mechanical testing of composites of LLDPE highly loaded with Al(OH)₃ showed that the strength and elongation at break were significantly improved after the grafting of MAA to the LLDPE matrix. The results of the electric tests showed similar trends. The results of scanning electron microscopy showed better decentralization of Al(OH)₃ loaded in the LLDPE matrix in the tensile fractured surface and a transition layer between Al(OH)₃ and the LLDPE matrix in the fractured surface after the grafting of MAA to the LLDPE matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 162–168, 2005     

Synthesis of a dripping agent based on lauric acid diethanolamide and delaying its migration in LLDPE films

ABSTRACT

Polymeric films are increasingly used in greenhouse cultivation because dripping agents can improve the hydrophilicity of film surface. Here, we summarize a way to a new reactive type dripping agent, lauric acid diethanolamide monoacrylate (AAL), which was synthesized by using acrylic and lauric acid diethanolamide as main starting materials. As-prepared AAL was separately grafted onto linear low-density polyethylene (LLDPE-g-AAL) and layered double hydroxides (LDHs-g-AAL) to prevent it from migrating. Accelerated dripping experiment results showed that the dripping time of LLDPE/LDHS-g-AAL and LLDPE-g-AAL films at 60°C was prolonged to 16 and 12 days from 8 days of ungrafted one, respectively.     

Effect of film draw temperature (FDT) on physical properties of polyethylene

Thin polymer films (0.06 mm thick) were prepared with LLDPE (coded as A) and LDPE (coded as D) at different film draw temperatures (FDTs) from 5 to 65°C. There was about a 42% enhancement of the tensile strength when the LLDPE film was drawn at 45°C and LDPE at 35°C and the ultimate elongation increased between 14 and 32%. When various additives were incorporated into these resins A and D, the tensile strength slightly decreased, but the ultimate elongation increased. Films which attained the highest tensile properties showed the maximum resistance against degradation by natural outdoor weathering. Although irradiation of these films by a gamma source caused reduction of their tensile properties, there was a general tendency of resisting this reduction with increase of the FDT. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 459–465, 2003     

LLDPE-g-AA的流变行为及力学性能

利用毛细管流变仪研究了线性低密度聚乙烯接枝丙烯酸 (LLDPE - g -AA)的流变行为。结果表明 ,在高的剪切应力下LLDPE -g -AA的表观粘度比纯LLDPE的小 ,并改进了树脂的流动性和加工性。LLDPE - g -AA的表观粘度随接枝丙烯酸含量的增加而降低 ,说明接枝到LLDPE分子链上的丙烯酸起到了内润滑剂的作用。利用Instron 112 1拉力机测试了LLDPE - g -AA的力学性能 ,结果表明其拉伸强度、杨氏模量和断裂伸长率与纯LLDPE相比没有明显的变化     

Preparation and characterization of grafting styrene onto LLDPE by cyclohexane compatibilization in suspension polymerization

A novel method of grafting styrene onto linear low‐density polyethylene (LLDPE) by suspension polymerization was systematically evaluated. Cyclohexane as a compatibilizer was introduced to swell and activate the surface of LLDPE molecular chain for amplifying the contact point of styrene monomer with LLDPE. A series of copolymer of grafting polystyrene (PS) onto LLDPE, known as LLDPE‐g‐PS, were prepared with different ratios of cyclohexane/styrene monomer and various LLDPE dosages. FTIR and ¹H NMR techniques both confirmed successful PS grafting onto the LLDPE chains. In addition, SEM images of LLDPE‐g‐PS particles showed that the cross‐section morphology becomes smooth and dense with suitable cyclohexane dosages, indicating a better compatibility between LLDPE and PS. The highest grafting efficiency was 28.4% at 10 mL/g cyclohexane and styrene monomer when 8% LLDPE was added. In these conditions, the LLDPE‐g‐PS elongation at break increased by about 30 times compared with PS. Moreover, thermal gravimetric analysis (TGA) demonstrated that LLDPE‐g‐PS possesses much higher thermal stability than pure PS. Therefore, the optimal amount of cyclohexane as compatibilizer could increase the grafting efficiency and improve the toughness of PS. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41671.     

Surface structure and adhesive properties of biaxially oriented polypropylene film grafted with poly(acrylic amide) using corona discharge

Corona discharge was explored as a means of forming chemically active sites on the surface of biaxially oriented polypropylene (BOPP) film. The active species formed in air was used to induce graft copolymerization of acrylic amide (AAM) in aqueous solution. The surface structure, hydrophilicity and adhesion of the grafted BOPP film were characterized by the extent of grafting, electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), peel strength and contact angle measurements. Surface graft‐copolymerization of AAM onto BOPP film by corona discharge in air can be carried out with high efficiency. With increasing copolymerization time, the degree of grafting of AAM onto BOPP increases. The degree of grafting achieved a relatively high value of 2.13 wt% for the conditions of 1 min corona discharge and a copolymerization reaction time of 2.5 hr in 20% AAM aqueous solution at 70°C. After corona discharge grafting, the contact angle of water on the BOPP film decreased and the peel strength increased compared with those for ungrafted BOPP film. The hydrophilicity and adhesion of BOPP were improved by surface graft copolymerization with AAM induced by corona discharge.     

Improving light converting properties with wettability of polyethylene film by rare earth complex Eu(GI)3Phen

ABSTRACT

Modern agriculture needs multifunctional greenhouse films to meet different needs. A novel method for improving light converting properties and wettability of polyethylene film was developed in this paper. Glycerin monostearic acid itaconic acid diester (GI) with a carboxyl group and double band was synthesized. Rare earth complex Eu(GI)₃Phen with Eu³⁺ as central ion has been obtained. Subsequently, a simple strategy of grafting it onto LLDPE backbone was employed to delay the migration of Eu(GI)₃Phen. The fluorescence spectrum indicated that the modified film emitted red light. Meanwhile, the accelerated dripping time of modified film was extended to 12 days.     

Surface modification of low‐density polyethylene (LDPE) film and improvement of adhesion between evaporated copper metal film and LDPE

To improve the interfacial adhesion between evaporated copper film and low‐density polyethylene (LDPE) film, the surface of LDPE films was modified by treating with chromic acid [K₂Cr₂O₇/H₂O/H₂SO₄ (4.4/7.1/88.5)]/oxygen plasma. Chromic‐acid‐etched LDPE was exposed to oxygen plasma to achieve a higher content of polar groups on the LDPE surface. We investigated the effect of the treatment time of chromic acid in the range of 1–60 min at 70°C and oxygen plasma in the range of 30–90 sec on the extent of polar groups created on the LDPE. We also investigated the surface topography of and water contact angle on the LDPE film surface, mechanical properties of the LDPE film, and adhesion strength of the evaporated copper metal film to the LDPE film surface. IR and electron spectroscopy for chemical analysis revealed the introduction of polar groups on the modified LDPE film surface, which exhibited an improved contact angle and copper/LDPE adhesion. The number of polar groups and the surface roughness increased with increasing treatment time of chromic acid/plasma. Water contact angle significantly decreased with increasing treatment time of chromic acid/plasma. Combination treatment of oxygen plasma with chromic acid drastically decreased the contact angle. When the treatment times of chromic acid and oxygen plasma were greater than 10 min and 30 sec, respectively, the contact angle was below 20°. With an increasing treatment time of chromic acid, the tensile strength of the LDPE film decreased, and the film color changed after about 10 min and then became blackened after 30 min. With the scratch test, the adhesion between copper and LDPE was found to increase with an increasing treatment time of chromic acid/oxygen plasma. From these results, we found that the optimum treatment times with chromic acid and oxygen plasma were near 30 min and 30 sec, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1677–1690, 2001     

Preparation of functionalized graphene/linear low density polyethylene composites by a solution mixing method

The surface modification of graphene as well as the characterization of modified graphene-based polymer composite prepared by solution mixing techniques was examined. X-ray photoelectron spectroscopy was employed to examine the surface modification and formation of graphene. The tensile strength of the composite increased with 3 wt.% of DA-G loading and was 46% higher than that of neat LLDPE. The onset thermal degradation temperature of the composite (3 wt.% of DA-G) was increased by ∼40 °C compared to neat LLDPE. A sharp increase in electrical conductivity of the composite was observed at 3 wt.% of DA-G content.     

光敏有机硅聚氨酯丙烯酸酯预聚体性能的研究

考查了光引发剂、活性单体对光敏有机硅聚氨酯丙烯酸酯预聚体（PSUA）胶膜的耐水性、拉伸强度、伸长率、硬度、柔韧性和热稳定性的影响。结果表明，胶膜具有优良的耐水性，吸水性低于4％。含单官能度单体的PSUA胶膜的接触角大于含多官能度单体的，含有IBOA的体系接触角达103．6°；当选择引发效率高的裂解型光引发剂，用量为0.5％～1％时，胶膜具有较高的接触角。含多官能度单体胶膜的拉伸强度高于含单官能度单体的体系，但伸长率较小。含TMPTA体系的胶膜的硬度最大，为0．575。胶膜具有较好的柔韧性和热稳定性，其柔韧性达到1mm级，在300℃时失重为4.61％。     

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).     

Surface modification of PVDF hollow fiber membrane to enhance hydrophobicity using organosilanes

This work investigates the membrane modification to enhance hydrophobicity aiming for applications as membrane contactors. The PVDF membranes were activated by NaOH and by plasma activation followed by grafting using three organosilanes. For the NaOH, the contact angle of original membranes (68°) was decreased from 44° to 31° with increasing NaOH concentration from 2.5M to 7.5M at 60°C for 3 h. The contact angle of NaOH treated membranes was increased to 100° after modification with 0.01M FAS‐C8 for 24 h. A needle‐like structure was observed on the membrane surface while there was no significant change in pore size and pore size distribution. Moreover, FTIR and XPS data showed Si peak and composition. The mechanical strength was improved. The surface modified membranes under helium plasma activation followed by grafting with 0.01M FAS‐C8 for 24 h showed higher contact angle, mechanical strength and surface roughness than that obtained by NaOH activation method while other physical properties did not change. The long‐term performance test for 15 days of operation was conducted. The modified membranes exhibited good stability and durability for CO₂ absorption. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Surface modification of polyethylene terephthalate film by CO2 laser‐induced graft copolymerization of acrylamide

Graft copolymerization of acrylamide onto polyethylene terephthalate (PET) using a CO₂ pulsed laser was performed to improve water wettability. After laser irradiation in air, the films were placed in the aqueous solution of monomer and then heated to decompose peroxides formed onto the irradiated PET film. Peroxide density was determined spectrophotometrically by means of the iodide method. The grafted PET surfaces were characterized by attenuated total reflectance infrared spectroscopy, scanning electron microscopy, and contact angle measurements. The electron micrographs showed that the grafting changed the surface morphology of the PET film, which is consistent with the infrared spectra of the grafted films. To evaluate the surface hydrophilicity, water drop contact angle was determined. The contact angle decreased as a result of graft polymerization. It was also found that the hydrophilicity is related to the surface morphology and grafting level. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 401–407, 2000     

Compounding of poly(dimethyl siloxane) to reduce tack in natural rubber

Tack in natural rubber latex was reduced by compounding poly(dimethyl siloxane) (PDMS) emulsion in concentrated latex. Sheet and dipped film surfaces were examined with Fourier transform infrared spectroscopy using attenuated total reflection (FTIR–ATR) and by contact angle measurements. Autohesive tack and tensile properties were also determined. For both sheet and dipped film, FTIR–ATR showed that the PDMS concentration was higher at the glass surface than at the air surface. The contact angle of ethylene glycol on the rubber decreased with increasing PDMS content. Autohesive tack for sheet and dipped film also decreased with increasing PDMS amount; however, annealing for 1 week at 70°C in air did cause tack to rise in the sheets. The rubber surface could be made nonadhesive by addition of sufficient PDMS. PDMS caused a decrease in tensile strength for the sheet, especially after annealing; however, PDMS did not cause a substantial decrease in percentage elongation for the sheets, except at relatively high PDMS contents. The tensile strength and percentage elongation for dipped film was not affected by PDMS over the much more limited PDMS concentration range studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 519–526, 2001     

Novel ternary blends of natural rubber/linear low-density polyethylene/thermoplastic starch: influence of epoxide level of epoxidized natural rubber on blend properties

Novel degradable materials based on ternary blends of natural rubber (NR)/linear low-density polyethylene (LLDPE)/thermoplastic starch (TPS) were prepared via simple blending technique using three different types of natural rubber (i.e., unmodified natural rubber (RSS#3) and ENR with 25 and 50 mol% epoxide). The evolution of co-continuous phase morphology was first clarified for 50/50: NR/LLDPE blend. Then, 10 wt% of TPS was added to form 50/40/10: NR/LLDPE/TPS ternary blend, where TPS was the particulate dispersed phase in the NR/LLDPE matrix. The smallest TPS particles were observed in the ENR-50/LLDPE blend. This might be attributed to the chemical interactions of polar functional groups in ENR and TPS that enhanced their interfacial adhesion. We found that ternary blend of ENR-50/LLDPE/TPS exhibited higher 100 % modulus, tensile strength, hardness, storage modulus, complex viscosity and thermal properties compared with those of ENR-25/LLDPE/TPS and RSS#3/LLDPE/TPS ternary blends. Furthermore, lower melting temperature (T _m) and heat of crystallization of LLDPE (?H) were observed in ternary blend of ENR-50/LLDPE/TPS compared to the other ternary blends. Also, neat TPS exhibited the fastest biodegradation by weight loss during burial in soil for 2 or 6 months, while the ternary blends of NR/LLDPE/TPS exhibited higher weight loss compared to the neat NR and LLDPE. The lower weight loss of the ternary blends with ENR was likely due to the stronger chemical interfacial interactions. This proved that the blend with ENR had lower biodegradability than the blend with unmodified NR.