开口剂母粒用于LDPE装置的研究

选用国内生产的3种原材料进行了开口剂母粒配方的研究,考察不同品种的开口剂母粒在低密度聚乙烯生产装置上的试用效果,并通过吹膜实验,考察开口剂母粒对薄膜制品物性的影响。研究结果表明．不同品种的开口剂母粒在装置上的使用效果存在一定差异,其中磷酸氢钙开口剂母粒效果最好;在薄膜牌号产品中加入一定量的开口剂母粒可以有效提高吹膜制品的开口性能,而且产品的力学性能变化不大,但对其光学性能略有影响。     

纳米硫酸钡用作膜聚酯开口剂的研究

在聚酯的合成过程中加入纳米硫酸钡,制备膜用聚酯开口剂母料。考察纳米硫酸钡对聚合反应的影响,对含有纳米硫酸钡的开口剂母料进行性能分析,用小试挤出流延机和拉膜机对硫酸钡开口剂母料进行铸片、制膜试验,考察成膜性能,对膜片进行性能分析。结果表明:纳米硫酸钡的加入对聚合过程无影响,用硫酸钡制备的聚酯开口剂母粒同用二氧化硅制备的开口剂母料性能指标基本相同。硫酸钡膜用聚酯开口剂母料制膜过程顺利,纳米硫酸钡作为开口剂的双向拉伸膜片的摩擦因数比二氧化硅作为开口剂的双向拉伸膜片的摩擦因数高。     

Natural weathering,artificial photo‐oxidation,and thermal aging of low density polyethylene: Grafting of acrylic acid onto aged polyethylene films

The photo‐oxidation and thermal initiation changes of commercial low density polyethylene (LDPE) films used in greenhouse covering, in the presence or absence of ultraviolet (UV) stabilizer, were monitored by infrared (IR) spectroscopy, by mechanical tests and by applying the grafting of acrylic acid onto the aged films. It was found that the resistance of PE films to UV irradiation and heat initiation as proved by tensile strength and elongation at break % was better for stabilized PE films compared with the unstabilized ones. A simple correlation was not observed between the fall in mechanical properties and the rate of film oxidation. On the other hand, an almost linear relation was obviously noticed between the degree of PE oxidation (C?O) measured by IR spectroscopy and the grafting level. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2365–2371, 2003     

Rice‐husk‐ash‐based silica as a filler for embedding composites in electronic devices

We carried out a feasibility study of the use of black rice husk ash (RHA) as a filler in epoxy resin for embedding material in electrical and electronic applications. We made a comparison by mixing RHA and two commercial fillers, fused and crystalline silica, with epoxy resin at weight fractions ranging from 20–60%. RHA‐filled epoxy resin had higher mixing viscosity, coefficient of thermal expansion, and water absorption percentage than commercial‐silica‐filled epoxy composite. However, the impact strength of all composites was comparable, but the tensile strength and elongation at break of silica‐filled epoxy were slightly superior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3013–3020, 2002     

Characterization to the weathering extent of LLDPE/LDPE thin film

A kind of LLDPE (linear low density polyethylene)/LDPE (low density polyethylene) thin film for farm applications was subjected to accelerated and natural weathering. Carbonyl group, melting point, tensile elastic modulus, and high‐temperature shearing modulus of weathered films were investigated as function of weathering time. Two kinds of carbonyl index, I₁ and I₂, which result from infrared spectroscopy (IR) spectra of the weathered films, were defined to characterize the weathering extent of the LLDPE/LDPE thin film. Based on I₁ and I₂, a correlation is made between the artificial and natural weathering of the film: 1 h of the artificial weathering is equivalent to about 10.73 h of the natural weathering. The difference between the accelerated weathering and the natural weathering was also discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 12–16, 2003     

LDPE composite films incorporating ceramic powder emitting far‐infrared radiation for advanced food‐packaging applications

A ceramic powder that emits far‐infrared radiation (FIR) was incorporated into low‐density polyethylene (LDPE) via melt‐compounding and subsequent melt‐extrusion processes. To investigate the feasibility of as‐prepared LDPE/FIR composite films for use in packaging applications, the composite films were characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, FIR emissivity and emissive power, antimicrobial activity assays, and storage tests. The physical properties and antimicrobial activities of the composite films were found to strongly correlate with the changes in the chemical and morphological structures that originate from different contents of FIR ceramic powder. A higher content of FIR ceramic powder in the LDPE/FIR composite film provided increased FIR emissivity and emission power of the composite and resulted in good antimicrobial activity. Storage tests also showed that incorporation of FIR ceramic powder into LDPE film was an effective method for maintaining the freshness of lettuce. Furthermore, the incorporation of FIR ceramic powder into LDPE films induced higher thermal stability and crystallinity and enhanced their barrier properties, which suggest these LDPE/FIR composite films are potential candidates for advanced packaging materials for the food and medical industries. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43102.     

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     

Novel,synergistic composites of polypropylene and rice husk ash: Sustainable resource hybrids prepared by solid‐state shear pulverization

Rice husk ash (RHA) is an agrowaste byproduct resulting from the incineration of rice husks for power production; white RHA is ∼90 wt% or more silica, which makes it a potentially sustainable and inexpensive substitute for commercial (less “green”) silica filler. Past research on polypropylene (PP)‐RHA hybrids made by melt processing has yielded modest increments in Young's modulus, reduced yield strength, and drastic reductions in elongation at break relative to neat PP. Using the industrially scalable solid‐state shear pulverization (SSSP) process, PP‐RHA hybrids are made with 4–38 wt% RHA. As determined by microscopy and other methods, composites made by SSSP have much better RHA dispersion than composites reported in the literature made by twin‐screw extrusion. The superior dispersion leads to major enhancements in tensile modulus (up to 100% increases relative to neat PP) while maintaining the yield strength of neat PP and remarkably high values of elongation at break (e.g., 520% at 19 wt% RHA), far higher than composites made by melt processing. The properties of hybrids made by SSSP are competitive with and in some cases superior to those of PP hybrids made with commercial silica. The PP‐RHA hybrids also exhibit major increases in hardness, approaching that of polycarbonate in the case of a 38 wt% RHA hybrid. The 38 wt% RHA hybrid exhibits solid‐like rheology at low frequency. Nevertheless, all PP‐RHA hybrids made by SSSP exhibit viscosities at moderate to high shear rates that are little changed from that of neat PP. POLYM. COMPOS., 34:1211–1221, 2013. © 2013 Society of Plastics Engineers     

Physicochemical properties of irradiated and loaded LDPE films with polyfunctional monomers

Polyfunctional monomers (PFMs), namely, trimethylol propane trimethacrylate (TMPTMA), trimethylol propane triacrylate, ethylene glycol dimethacrylate, and diethylene glycol diacrylate were blended with low‐density polyethylene (LDPE) and exposed to different doses of EB irradiation. Fourier transform infrared and ultraviolet and UV–vis spectroscopy of the unirradiated, irradiated, unloaded, and PFMs‐loaded LDPE films were studied under various irradiation doses up to 300 kGy. The degree of crosslinking and oxidative degradation, as measured by the spectroscopic parameters, were dependent on both the irradiation dose and the type of loaded PFMs. For all of the loaded monomers, the extent of crosslinking increased at different rates as a function of irradiation dose. TMPTMA monomer was the most efficient in enhancing the crosslinking of LDPE films compared to the other loaded monomers. However, the unloaded LDPE film showed the least extent of crosslinking. In addition, the EB‐radiation‐induced changes, such as trans‐vinylene formation, a decrease in vinyl and vinylidene unsaturation; and carbonyl double‐bond formation and change in crystallinity were correlated. The importance of these results on the prediction of the role of polyfunctional monomers in the production of crosslinked polymers is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2025–2035, 2003     

易开口、高透明线性低密度聚乙烯的研制与应用

采用助剂配方后改性的技术方法,研制开发出生产易开口、高透明线性低密度聚乙烯(LL-DPE)的助剂配方体系。考察了自主研发的增透剂、有机和无机开口剂等助剂的不同质量比对LLDPE膜的光学性能和开口性能的影响;并且在LLDPE装置上实现了工业化应用。     

Oxygen enrichment from air through multilayer thin low‐density polyethylene films

Several multilayer thin low‐density polyethylene (LDPE) films were fabricated by blown thin film having a thickness of 7 μm and an area of 130 cm². They were characterized for their oxygen‐enrichment performance from air by a constant pressure–variable volume method in a round permeate cell with an effective area of 73.9 cm². The relationship between oxygen‐enrichment properties, including oxygen‐enriched air (OEA) flux, oxygen concentration, permeability coefficients of OEA, oxygen, nitrogen, as well as separation factor through the multilayer LDPE films, and operating parameters, including transfilm pressure difference, retentate/permeate flux ratio, temperature, as well as layer number, are all discussed in detail. It is found that all of the preceding oxygen‐enrichment parameters increase continuously with an increase of transfilm pressure difference from 0.1 to 0.65 MPa, especially for the trilayer and tetralayer LDPE films. The oxygen concentration and separation factor appear to rapidly increase within the retentate/permeate flux ratio below 200, and then become unchangeable beyond that, whereas the OEA flux and the permeability coefficients of OEA, oxygen, and nitrogen seem to remain nearly constant within the whole retentate/permeate flux ratio investigated, especially for the monolayer and bilayer LDPE films. The selectivity becomes inferior, whereas the permeability becomes superior, as the operating temperature increases from 23 to 31°C. The highest oxygen concentration was found to be 44.8% for monolayer LDPE film in a single step with air containing oxygen of 20.9% as a feed gas and operating pressure of 0.5 MPa at a retentate/permeate flux ratio of 340 and 23°C. The results demonstrate a possibility to prepare an oxygen‐enriching membrane directly from air, based on the easily obtained thin LDPE films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3013–3021, 2002; DOI 10.1002/app.2331     

Correlations between processing parameters,morphology, and properties of blown films of LLDPE/LDPE blends,part 2: Crystalline and amorphous biaxial orientation by WAXD pole figures

The biaxial molecular orientation of blown films made of blends of linear low density polyethylene (LLDPE) with low density polyethylene (LDPE) was characterized by two different methods: complete pole figures obtained by wide angle X‐rays diffraction (WAXD) and polarized infrared spectroscopy (IR) using the Krishnaswamy approach. The molecular orientation of the blends amorphous phase was also evaluated by polarized IR. The crystallinity of the blown films was determined by WAXD. A good correlation between the X‐ray pole figures and the polarized IR results was obtained. At all blends compositions, it was shown that the a‐axis of the polyethylene orthorhombic cell was preferentially oriented along the machine direction, the orientation degree along this direction increasing with the increase of the LDPE amount in the blends. The b‐axis changed its preferential orientation from film thickness in the 100/0 LLDPE/LDPE film to along the transverse direction with increasing LDPE in the blends. The c‐axis changed its orientation from orthogonal to normal direction in the 100/0 LLDPE/LDPE film to along the film thickness with increasing LDPE in the blends. Polarized IR characterization showed a negligible orientation of the amorphous phase. The amount of crystallinity was dependent on blend composition decreasing with the increase of LDPE content in the blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2760–2767, 2006     

Physicomechanical,optical, barrier,and WAXS studies of filled linear low‐density polyethylene films

Linear low‐density polyethylene (LLDPE) with different fillers such as silica, mica, and soy protein isolate were compounded using a single screw extruder and blown into films by a Konark blow‐film machine. The filled LLDPE films were characterized for physicomechanical and optical properties. Barrier properties such as water vapor transmission rate and oxygen transmission rate of the filled LLDPE films were also reported. Microcrystalline parameters such as crystal size (〈N〉) and lattice distortion (g in %) of the filled LLDPE films were estimated from the wide‐angle X‐ray scattering method using Hosemann's paracrystalline model. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2938–2944, 2003     

Crystallization kinetics of low‐density polyethylene and polypropylene melt‐blended with a low‐Tg tin‐based phosphate glass

The nonisothermal and isothermal crystallizations of low‐density polyethylene (LDPE) and polypropylene (PP) in phosphate glass (Pglass)–polymer hybrid blends were studied through differential scanning calorimetry (DSC). As the Pglass volume fraction was increased, the percentage crystallinity decreased. The half‐time for crystallization decreased as the propagation rate constant rose, for both of the polymer matrices, with increasing Pglass concentrations. The Pglass was observed to be a nucleating agent for formation of two‐ or three‐dimensional spherulites in the hybrids. Tensile modulus improved for both of the Pglass–polymer hybrids up to 40% Pglass, but the energy to break decreased. Tensile strength changed slightly with the addition of Pglass to the LDPE matrix, exhibiting a larger value than that of pure LDPE at 30%. The tensile strength decreased as more Pglass was added to the PP matrix. The observed differences between tensile properties of the Pglass–PP and Pglass–LDPE hybrids at identical Pglass volume concentration were found to be consistent with that of the crystallization behavior of the hybrids. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3445–3456, 2003     

Effects of polyethylene‐grafted maleic anhydride (PE‐g‐MA) on thermal properties,morphology, and tensile properties of low‐density polyethylene (LDPE) and corn starch blends

The effects of polyethylene‐grafted maleic anhydride (PE‐g‐MA) on the thermal properties, morphology, and tensile properties of blends of low‐density polyethylene (LDPE) and corn starch were studied with a differential scanning calorimeter (DSC), scanning electron microscope (SEM), and Instron Universal Testing Machine, respectively. Corn starch–LDPE blends with different starch content and with or without the addition of PE‐g‐MA were prepared with a lab‐scale twin‐screw extruder. The crystallization temperature of LDPE–corn starch–PE‐g‐MA blends was similar to that of pure LDPE but higher than that of LDPE–corn starch blends. The interfacial properties between corn starch and LDPE were improved after PE‐g‐MA addition, as evidenced by the structure morphology revealed by SEM. The tensile strength and elongation at break of corn starch–LDPE–PE‐g‐MA blends were greater than those of LDPE–corn starch blends, and their differences became more pronounced at higher starch contents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2904–2911, 2003     

Gamma‐ray irradiation effect of polyethylene on dimaleimides as a class of new multifunctional monomers

Multifunctional monomers, m‐xylylenedimaleimide, p‐phenylenedimaleimide, m‐phenylenedimaleimide, and p‐phenylenedinadimide, all of which have maleimide groups, were synthesized to increase thermal and radiation stabilities. The synthesized multifunctional monomers showed good compatibility with low‐density polyethylene (LDPE). Mixtures of LDPE and these multifunctional monomers were irradiated with γ‐rays from a Co‐60 source at room temperature in a nitrogen atmosphere. The absorbed dose ranged from 0 to 160 KGy. Among these multifunctional monomers, m‐xylylenedimaleimide was the best in gel fraction enhancement. Crosslinked LDPE with m‐xylylenedimaleimide displayed a higher modulus than that of crosslinked LDPE with triallyl cyanurate. For the elongation property, LDPE with m‐xylylenedimaleimide as a multifunctional monomer showed better results than that with commercial multifunctional monomers such as triallyl cyanurate (TAC) and trimethylol propane triacrylate (TMPTA). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2339–2345, 2003     

Application of paraffin and silver coated titania nanoparticles in polyethylene nanocomposite food packaging films

In this work, 3% and 5% TiO₂/Ag nanoparticles were dispersed in low‐density polyethylene through melt blending process, and subsequently nanocomposite films were prepared by hot pressing. Paraffin was used for the first time in this work as compatibilizer agent. The effect of TiO₂/Ag nanoparticle content, as well as compatibilizer dosage on the antimicrobial, morphological, mechanical, and optical performance of the nanocomposite films was investigated. Improved mechanical properties of the nanocomposite films were found on using paraffin as compatibilizer in comparison with the neat low‐density polyethylene (LDPE) films. The optical study results also showed that the addition of TiO₂/Ag to the LDPE films does not drastically change the film appearance other than making them more reddish. The fabricated nanocomposites presented in this study could be a suitable choice for food packaging (subject to further investigation of the food packaging behavior). The results showed that both TiO₂/Ag nanoparticle and compatibilizer are needed to prevent the bacteria growth in the film. The best result was obtained by using 5% nanoparticle and 4% paraffin compatibilizer where the bacteria growth rate was significantly reduced by 95%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45913.     

Effects of rosin‐type nucleating agent and low density polyethylene on the crystallization process of polypropylene

In this article, the influence of rosin‐type nucleating agent (Nu–Na) and low density polyethylene (LDPE) on the crystallization process of polypropylene (PP) from the melt state was studied by differential scanning calorimeter and polarization microscope. It was found that LDPE obstructed the crystallization of PP, decreased the crystallization rate of PP. The rosin‐type nucleating agent Nu–Na substantially improved the rate of crystallization, and decreased the size of spherulites also. The cooperative effect of LDPE and Nu–Na made the crystallization rate of PP increase greatly, the spherulites of PP became much smaller and dispersed more uniformly, and the transparency of PP was further improved evidently. The crystallization temperature (T_c) and melting temperature (T_m) of PP and LDPE in PP/LDPE/Nu–Na (97:3:0.5) were not affected by the number of mixed passes—the nuclei migration from PP to PE had not happened in the mixed passes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2804–2809, 2003     

γ‐Irradiated poly(tetrafluoroethylene) particle‐filled low‐density polyethylene. I. Effect of silane coupling agents on mechanical,thermal, and morphological properties

Poly(tetrafluoroethylene) (PTFE) scraps were recovered as a filler material for low‐density polyethylene (LDPE) after they were degraded by Co‐60 γ‐rays under atmospheric conditions to make small‐size powder. The powder PTFE, which was called secondary PTFE (2°‐PTFE), was melt mixed with LDPE and then extruded to obtain 200 µm films. The mechanical and thermal properties and also the morphology of the fractured surface of these 2°‐PTFE–filled LDPE were studied. It was found that the addition of 2°‐PTFE resulted in thermofilm property of LDPE but it slightly decreased the thermal oxidative temperature of LDPE. The tensile strength and ultimate elongation of LDPE were found to decrease with the addition of 2°‐PTFE. However, when it is compared to the addition of virgin PTFE into LDPE, 2°‐PTFE shows better mechanical properties due to the presence of oxy groups which are capable of interacting with the main matrix. A further improvement in mechanical properties was achieved by silane coupling agent treatment of 2°‐PTFE. Silane coupling agents were found to enhance the interfacial adhesion between 2°‐PTFE and LDPE. The study on the fractured surfaces by scanning electron microscope revealed this adhesion between these two polymers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 866–876, 1999     

Photodegradation of some low‐density polyethylene–montmorillonite nanocomposites containing an oligomeric compatibilizer

The photo‐oxidation behavior at the exposed surfaces of maleated low‐density polyethylene [LDPE poly(ethylene‐co‐butylacrylate‐co‐maleic anhydride) (PEBAMA)] and montmorillonite (MMT) composites was studied using attenuated total reflection Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy (TEM), and mechanical testing. Two different MMT clays were used with the maleated polyethylene, an unmodified clay, MMT, and an organically modified montmorillonite (OMMT) clay which was significantly exfoliated in the composite. The morphologies of sample films were examined by XRD and TEM. The results were explained in terms of the effect of the compatibilizing agent PEBAMA on the clay dispersion. It was found that the OMMT particles were exfoliated in the polymer matrix in the presence of the PEBAMA, whereas the MMT clay particles were agglomerated in this matrix. Both mechanical and spectroscopic analyses showed that the rates of photo oxidative degradation of the LDPE‐PEBAMA–OMMT were higher than those for LDPE and LDPE‐PEBAMA–MMT. The acceleration of the photo‐oxidative degradation for LDPE‐PEBAMA–OMMT is attributed to the effects of the compatibilizer and the organic modifier in the composite. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40788.