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.     

Surface graft copolymerization of 2‐hydroxyethyl methacrylate onto low‐density polyethylene film through corona discharge in air

The corona discharge technique was explored as a means of forming chemically active sites on a low‐density polyethylene (LDPE) film surface. The active species thus prepared at atmospheric pressure in air was exploited to subsequently induce copolymerization of 2‐hydroxyethyl methacrylate (HEMA) onto LDPE film in aqueous solution. The results showed that with the corona discharge voltage, reaction temperature, and inhibitor concentration in the reaction solution the grafting degree increased to a maximum and then decreased. As the corona discharge time, reaction time, and HEMA concentration in the reaction solution increased, the grafting degree increased. With reaction conditions of a 5 vol % HEMA concentration, 50°C copolymerization temperature, and a 2.0‐h reaction time, the degree of grafting of the LDPE film reached a high value of 158.0 μg/cm² after treatment for 72 s with a 15‐kV voltage at 50 Hz. Some characteristic peaks of the grafted LDPE came into view at 1719 cm^?1 on attenuated total reflectance IR spectra (C?O in ester groups) and at 531 eV on electron spectroscopy for chemical analysis (ESCA) spectra (O_1s). The C_1s core level ESCA spectrum of HEMA‐grafted LDPE showed two strong peaks at ～286.6 eV (? C ? O? from hydroxyl groups and ester groups) and ～289.1 eV (O?C ? O? from ester groups), and the C atom ratio in the ? C? O? groups and O?C? O groups was 2:1. The hydrophilicity of the grafted LDPE film was remarkably improved compared to that of the ungrafted LDPE film. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2881–2887, 2001     

Surface modification of low‐density polyethylene films by UV‐induced graft copolymerization with a fluorescent monomer

Surface modification of argon plasma–pretreated low‐density polyethylene (LDPE) film via UV‐induced graft copolymerization with a fluorescent monomer, (pyrenyl)methyl methacrylate (Py)MMA, was carried out. The chemical composition and morphology of the (Py)MMA‐graft‐copolymerized LDPE [(Py)MMA‐g‐LDPE] surfaces were characterized, respectively, by X‐ray photoelectron spectroscopy (XPS) and by atomic force microscopy (AFM). The concentration of the surface‐grafted (Py)MMA polymer increased with Ar plasma pretreatment time and UV graft copolymerization time. The photophysical properties of the (Py)MMA‐g‐LDPE surfaces were measured by fluorescence spectroscopy. After graft copolymerization with the fluorescent monomer, the surface of the LDPE film was found to have incorporated new and unique functionalities. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1526–1534, 2001     

The study of melt grafting mechanism of acrylic acid and butyl acrylate onto low density polyethylene and its application as internal plasticizer

Melt grafting of acrylic acid (AA) and butyl acrylate (BA) (equal molar ratios) onto low‐density polyethylene (LDPE) was carried out in Haake internal mixter by free radical grafting copolymerization. The graft degree of AA and BA in the grafted LDPE (LDPE‐g‐(AA+BA)) was determined by FTIR. The influences of initiator on the graft degree of AA and BA, melt flow rate (MFR), and gel content were investigated, and the optimum conditions were obtained. The successive self‐nucleation/annealing (SSA) thermal fraction method was used to characterize the molecular structure and polydispersity of LDPE‐g‐(AA+BA) with various graft degrees. The effects of thermal fraction parameters on fraction of LDPE‐g‐(AA+BA) were investigated. On the basis of the results of SSA, the grafting reaction mechanism of AA and BA onto LDPE was proposed, i.e., grafting reaction preferentially occurred on the tertiary carbons of LDPE. The grafted LDPE possessed suitable reactivity and rheological property. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Surface photografting of low-density polyethylene films and its relevance to photolamination

Surface modifications of pristine and ozone-pretreated low-density polyethylene (LDPE) films were carried out via UV-induced graft copolymerization with a photoinitiator-containing, epoxy-based commercial monomer (DuPont Somos? 6100 for solid imaging and optical lithography) and also with the photoinitiator-free acrylic acid (AAc). The chemical composition and microstructure of the graft copolymerized surfaces were studied by angle-resolved X-ray photoelectron spectroscopy (XPS). The concentration of surface grafted polymer increased with the UV illumination time and the monomer concentration. For LDPE films graft copolymerized with the epoxy-based monomer, surface chain rearrangement was not observed or was less well pronounced, due to the partial crosslinking of the grafted chains. Simultaneous photografting and photolamination between two LDPE films, or between a LDPE film and a poly(ethylene terephthalate) (PET) film, in the presence of either monomer system, were also investigated. The photolamination rates and strengths depend on the ozone pretreatment time, the UV illumination time, and the UV wavelength, as well as on the nature of the substrate materials. A shear adhesion strength approaching 150 N/cm² could be achieved with either monomer system, provided that the polymer films were pretreated with ozone. The failure mode of the photolaminated surfaces was cohesive in nature in the case of the photoinitiator-containing epoxy monomer, but was either cohesive or adhesional in nature (depending on the substrate assembly) in the case of the photoinitiator-free AAc monomer.     

Radiation Synthesis of Grafted Polymers for Studying Thermoluminescence Characterization and Its Possible Application as a Dosimeter at Low Doses

Radiation-induced graft copolymerization of binary monomer system acrylic acid/acrylamide (AAc/AAm) (50/50) onto low density polyethylene (LDPE) and polypropylene (PP) films were investigated. Sulfonation was carried out for the prepared graft copolymers using concentrated sulfuric acid (97%) at 60°C for 15 min. The sulfonated grafted films found to have a thermal stability and better hydrophilic character than the grafted ones due to the ionic character resulting from this conversion. The thermoluminescence (TL) characteristics of grafted and sulfonated films were studied with regard to their use as off-line dosimeters in radiotherapy. The structural characterizations were performed by using FTIR, DSC and TGA. The sulfur content was determined by elemental analysis (EA). The TL responses were tested with ⁶⁰Co beam in the dose range 0.1–7 Gy. The dosimetric characterization has yielded a very good reproducibility, and independence of the radiation energy. The TL signal is not influenced by the dose rate and exhibits a very low thermal fading. Moreover, the sensitivity of the samples compares favorably than that of standard TLD-100 dosimeters. Finally, at the same dose the TL response for LDPE-g-P (AAm/AAc) films is higher than that of PP-g-P (AAm/AAc) and the sulfonated grafted films are more sensitive to radiation than the grafted ones.     

Synthesis and characterization of biodegradable polyethylene by graft copolymerization of starch using glucose–Ce(IV) redox system

Graft copolymerization of low‐density polyethylene (LDPE) onto starch was carried out with glucose–cerium(IV) redox initiator in an aqueous sulfuric acid medium under nitrogen atmosphere. The graft yield was influenced by various parameters like reaction time, temperature, and concentrations of acid, glucose, polyethylene (PE), starch, and initiator. A maximum graft yield of 85.66% was obtained at a temperature of 50°C and at higher concentration of starch. Effect of grafting on crystallinity, morphology, and thermal properties of modified PE has been evaluated using X‐ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA/DTA). Biodegradability of starch‐grafted PE has been tested applying soil‐burial test. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3229–3239, 2006     

Selective removal of some heavy metal ions from aqueous solution using treated polyethylene-g-styrene/maleic anhydride membranes

Radiation graft copolymerization of styrene/maleic anhydride (Sty/MAn) comonomer onto low density polyethylene (LDPE) membrane was investigated. The prepared grafted membranes were treated with different reagents containing various functional groups and studied as a matrix for the purpose of water purification from heavy metals. The metal ion uptake by the functional groups of membranes was determined by the use of X-ray fluorescence (XRF) and atomic absorption (AA). The effect of pH of the metal feed solution and immersion period needed for maximum capacity was investigated. The selectivity of different prepared membranes towards some selected metal ions such as Fe, Cu, Pb,… etc. which commonly exist in waste water was determined. The affinity of the treated grafted films to recover Fe(III), Cu(II) or Pb(II) from their aqueous solutions containing other metal ions such as Cd(II), Ni(II) or Hg(II) was studied. Also the selectivity of treated grafted membranes towards Cu(II), Cr(III) and Fe(III) in a mixture was investigated at room temperature and 70°C. It was found that the thiosemicarbazide-, hydroxylamine·HCl- and NaOH-treated grafted films showed high selectivity towards Cu(II), Cr(III) and Fe(III), respectively, at 70°C. However, the selectivity of such treated grafted membranes was remarkable towards Fe(III) at room temperature. The results obtained suggested that the treated grafted membrane possessed good chelating properties towards different metal ions. This suggests that such membranes could be accepted for practical uses.     

Low-temperature graft copolymerization of 1-vinyl imidazole on low-density polyethylene films with simultaneous lamination of copper foils

Surface modification of argon plasma-pretreated low-density polyethylene (LDPE) films by graft copolymerization with 1-vinyl imidazole (VIDz) and with concurrent lamination of copper foils at room temperature and at an elevated temperature were carried out. The adhesion strengths were reported as lap shear adhesion strengths and T-peel strengths. The surfaces of the graft copolymerized films and the mechanically delaminated LDPE and Cu surfaces were characterized by X-ray photoelectron spectroscopy (XPS). It was found that plasma pretreatment of LDPE alone, and in the absence of VIDz, could give rise to strong lap shear adhesion between the polymer and copper. Significant T-peel strengths, however, were obtained only for LDPE/Cu laminates obtained from the simultaneous graft copolymerization and lamination technique. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1977–1983, 1998     

接枝LDPE与PET共混物的热力学性能和相形态研究

通过红外光谱对合成的三种极性单体接技LDPE进行了确证,采用热分析仪和扫描电镜研究了接枝LDPE/PET共混物的热力学性能和相形态结构。结果表明,接枝LDPE与PET共混,对PET结晶过程有一定的加速促进作用;由缺口冲击断面观察发现,接枝LDPE以分散相分布在PET连续相中,但相界面之间有丝状物相连,说明接枝LDPE与PET有较好的相容性。     

Dyeability and swelling properties of graft copolymers of LDPE with 2‐hydroxypropyl methacrylate monomer prepared by gamma radiation

Low density polyethylene (LDPE) films were grafted with 2‐hydroxypropyl methacrylate (HPMA) monomer by gamma radiation. The LDPE graft copolymer was characterized by FTIR spectroscopy, tensile mechanical testing, and thermogravimetric analysis (TGA). The dye affinity of LDPE graft copolymers for different dyestuffs was studied. Also, the effect of temperature on the swelling characters of LDPE‐g‐HPMA was investigated. The TGA study showed that the LDPE graft copolymers, over the studied graft yields, possessed higher thermal stability than pure LDPE polymer. While, LDPE has no dye affinity for any of the known dyestuffs, LDPE graft copolymers displayed a unique dye affinity for a wide range of dyestuffs belonging to different classes. The results showed that the equilibrium swelling of LDPE graft copolymers in water reached after 7 h. In addition, the results showed that the swelling of LDPE graft copolymers was influenced by temperature within the temperature range 10–40°C. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

玉米秸秆制取高吸水树脂及性能研究

将玉米秸秆进行提纯改性,采用过硫酸钾(KSB)为引发剂、N,N-亚甲基双丙烯酰胺(MBAM)为交联剂,使其与丙烯酸接枝共聚合成农用高吸水树脂,通过试验对比最终确定最佳条件为改性玉米秸秆与丙烯酸的质量比为1∶6、丙烯酸中和度为70%、反应时间为4h、烘干温度为60°C;对最佳条件下制备的树脂进行了吸水倍率的测试;对秸秆预处理前后及接枝产物进行了红外谱图分析。结果表明,该树脂具有良好的吸水率,吸收去离子水达843倍,丙烯酸成功接枝在秸秆纤维素的主链上。     

Investigation on the oxidation of surface layers of polyolefins treated with corona discharge

The results of an X-ray photoelectron spectroscopic investigation of the oxidation of surface layers of low-density polyethylene (LDPE) and biaxially oriented polypropylene (BOPP) films are presented. The analysis was performed using different take-off angles, namely 10°, 30°, and 90°; thus, the depths of the examined layers were 0.6, 1.9, and 3.7 nm, respectively. It was found that the course of the oxidation process in the surface layers was similar for both polymer films. However, for treatment energies lower than 5 kJ/m², the extent of the oxidation was higher for the LDPE film, whereas for energies above this value, the BOPP film was more oxidized. As detected by X-ray photoelectron spectroscopy (XPS), desorption of oxygen from the film surface occurs for both polymers during the treatment.     

Multiple melting and partial miscibility of ethylene‐vinyl acetate copolymer/low density polyethylene blends

Multiple melting behaviors and partial miscibility of ethylene‐vinyl acetate (EVA) copolymer/low density polyethylene (LDPE) binary blend via isothermal crystallization are investigated by differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD). Crystallization temperature T (°C) is designed as 30, 50, 70, 80°C with different crystallization times t (min) of 10, 30, 60, 300, 600 min. The increase of crystallization temperature and time can facilitate the growth in lateral crystal size, and also the shift of melting peak, which means the completion of defective secondary crystallization. For blends of various fractions, sequence distribution of ethylene segments results in complex multiple melting behaviors during isothermal crystallization process. Overlapping endothermic peaks and drops of equilibrium melting points of LDPE component extrapolated from Hoffman–Weeks plots clarify the existence of partial miscibility in crystalline region between EVA and LDPE. WAXD results show that variables have no perceptible influence on the predominant existence of orthorhombic crystalline phase structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Chemically Induced Graft Copolymerization of Methacrylic Acid onto Low Density Polyethylene Films Using Sodium Bisulfite

Abstract

A simple and inexpensive technique for preparation of membranes by chemically induced graft copolymerization of methacrylic acid (MAA) onto low-density polyethylene (PE) films using sodium bisulfite (SBS) initiator was developed. Several parameters affecting the grafting rate and yield, such as the concentration of aqueous monomer solutions (4–20%) and initiator (0.025–0.2 M/L), reaction temperature (50–70°C), and within reaction times ranging from 1 to 6 h were studied. The results show that grafted films with 20% up to 500% graft were obtained under the synthesis conditions mentioned. Some selective properties of the grafted films (membranes), such as swelling behavior and mechanical properties were investigated. Also, the films were characterized by infrared (IR) spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). Such prepared graft copolymers may be of great interest in some practical uses such as dialysis and ultrafiltration membranes and also for wastewater treatment from heavy and toxic metals.     

Structural characterization of alpha methyl styrene‐butyl acrylate‐grafted polyetheretherketone films

Radiation‐induced graft copolymerization of alpha methyl styrene (AMS)‐butyl acrylate (BA) mixture onto poly(etheretherketone) (PEEK) was carried out to develop films of varying copolymer compositions. The characterization of films was carried out with fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The presence of AMS and BA units within the film matrix was confirmed by FTIR. The intensity of the characteristic peaks for AMS and BA increased with the increasing grafted component in the films. The crystallinity of the films as observed from DSC and XRD decreased with the increasing graft levels. On the other hand, the melting temperature of the base polymer was almost unaffected by irradiation and the grafting process. The glass transition temperature (T_g) of the grafted film increased as compared to the virgin PEEK. Ungrafted film showed a stable thermogram up to ～500°C. However, the grafting introduced a new decomposition range in the copolymer, due to the presence of the AMS/BA. AFM images showed the formation of domains on the grafted PEEK film surface. The SEM also showed domain formation of the grafted component within the PEEK matrix. However, the fracture analysis did not show any prominent phase separation. Mechanical characterization of films in terms of tensile strength, elongation, and modulus was also carried out. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

以Fe~(2+)-H_2O_2氧化还原体系引发木薯淀粉与醋酸乙烯酯接枝共聚反应研究

研究了以Fe2+-H2O2为引发剂的木薯淀粉与醋酸乙烯酯的接枝共聚反应,并对重要的反应条件进行了讨论。结果表明:当单体与淀粉的质量配比为1.0~2.0,引发剂浓度为1.0 mmol/L,H2O2与Fe2+的摩尔比为2,反应温度为40°C,反应时间为3 h,采用Fe2+→单体→H2O2的加料顺序时,可以得到较高的转化率、接枝率、接枝效率,分别为86.47%、55.30%及31.98%,并探讨Fe2+-H2O2的引发机理。通过Srectrum One红外光谱及电镜对接枝物的结构进行了分析。     

Correlation between different microstructural parameters and tensile modulus of various polyethylene blown films

The objective in this study is to establish a model for the prediction of tensile properties using various types of polyethylene films (LLDPE, HDPE, and LDPE). A series of blown films were produced by varying three process parameters: take‐up ratio, blow‐up ratio, and frost line height. The tensile properties of the resulting films were investigated in relation to their microstructural characteristics. The microstructural parameters were determined by differential scanning calorimetry, wide angle X‐ray diffraction (WAXD) pole figures, SAXS (small angle X‐ray diffraction), and birefringence measurements. The orientation parameters of the films were measured by WAXD and birefringence. They were determined for both crystalline and amorphous phases. The crystalline content, lamellar thickness, and crystal sizes were obtained from DSC and WAXD. The SAXS technique was used to find the average length of the crystalline and amorphous layers. A model for the tensile modulus is proposed and correlated to some structural parameters including crystallinity, orientation factors for crystalline c‐axis and amorphous phase, lamellar thickness, crystal size, the average length of the crystal layer, and long spacing period. The measured modulus and the calculated one were compared and a reasonable agreement was found between them for all series of films. POLYM. ENG. SCI., 47:1430–1440, 2007. © 2007 Society of Plastics Engineers     

高锰酸钾引发聚酯纤维接枝共聚改性研究

研究了用KMnO_4/H_2SO_4作为引发剂,聚酯(PET)纤维与丙烯酸接枝共聚的改性方法,探讨了间甲酚浸泡时间和温度、KMnO_4浓度、H_2SO_4浓度、丙烯酸(AA)浓度等对接枝率的影响。结果表明:间甲酚浸泡时间2h、浸泡温度60℃、KMnO_4浓度3.0×10~(-3)mol/L、H_2SO_4浓度0.02mol/L、AA浓度2.66mol/L、反应时间2h时,PET纤维的接枝率较高;同时,用红外光谱证明了聚丙烯酸接枝支链的存在。     

Protonation of polyaniline by surface-functionalized polymer substrates

The protonation of solution-coated emeraldine (EM) base by sulfonic and carboxylic acid groups on surface-functionalized low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), poly(ethylene terephthalate) (PET), and polytetrafluoroethylene (PTFE) films were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and conductivity measurements. Surface functionalizations were achieved by sulfonation (for LDPE, HDPE, PP, and PET), by hydrolysis (for PET), and by near-UV-light-induced surface graft copolymerization with the Na salt of styrene sulfonic acid and acrylic acid (for all substrates). The efficiency of surface functionalization by graft copolymerization is substantially enhanced for substrates pretreated with O₃ or Ar plasma. Protonation levels of 50% can be readily achieved for EM coated on sulfonic acid, but not carboxylic acid, functionalized surfaces. The extent of protonation, however, is also dependent on the microstructures of the modified substrate surfaces. In all cases, charge transfer interactions between the EM layer and the functionalized substrates readily result in good adhesion of the electroactive polymer on the polymer substrates to give rise to conductive surface structures. © 1995 John Wiley & Sons, Inc.