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.     

茂金属中密度聚乙烯的性能及加工应用

对茂金属中密度聚乙烯(MDPE)的结构与性能进行表征,并对其挤出和吹膜加工应用进行分析.结果表明,小试聚合得到的MDPE具有较窄的相对分子质量分布、较低的支化度,且拉伸屈服强度、弯曲强度显著高于线性低密度聚乙烯(LLDPE),冲击强度特别是低温冲击强度高于高密度聚乙烯(HDPE);MDPE属于假塑性流体,在低温时容易出现不稳定流动现象,在高剪切速率下可以观察到粘度和压力的异常反转现象;可在现有加工LLDPE的设备上顺利进行挤出、吹膜加工,且得到的薄膜在纵横向具有均匀性屈服强度、撕裂强度方面优于进口高性能LLDPE产品.     

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.     

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.     

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     

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     

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.     

硅烷交联EVA改性LLDPE材料

以过氧化二苯甲酰(BPO)为引发剂,乙烯基三甲氧基硅烷(A171)为交联剂和二月桂酸二丁基锡(DBTDL)为催化剂,采用两步法制备硅烷交联线型低密度聚乙烯(LLDPE),并添加适量的乙烯-醋酸乙烯共聚物(EVA)对产品进行改性。探究了温度、引发剂的用量、交联剂的用量对体系的接枝率、交联度、耐热性能和力学性能的影响。结果表明:在其他条件不变的情况下,在110~130℃范围内提高温度,可使凝胶率、维卡软化温度、拉伸强度先升高后降低,断裂伸长率降低;增加BPO的用量可以使凝胶率、维卡软化温度升高,断裂伸长率减小,拉伸强度先增大后减小;增加硅烷的用量可以使凝胶率、维卡软化温度、拉伸强度和断裂伸长率都升高。     

利用回收LDPE/PVDC复合薄膜制备共混材料的研究

以回收低密度聚乙烯/聚偏氯乙烯(LDPE/PVDC)复合薄膜为基体材料,低密度聚乙烯接枝丙烯酸(LDPE-g-AA)为相容剂,线型低密度聚乙烯(LLDPE)为改性剂,再加入液体钙-锌(Ca-Zn)热稳定剂,通过混合、挤出、注塑工艺制备共混材料。采用刚果红法分析了Ca-Zn稳定剂对复合薄膜中PVDC热稳定性能的影响,并对共混材料的力学性能、阻隔性能和微观形态进行了测试与分析。结果表明:加入1.2份Ca-Zn稳定剂后,共混材料的刚果红试纸起始变色时间和完全变色时间分别延长了67 s和354 s,起始变色温度和完全变色温度分别提高了8℃和11℃;含3%LDPE-g-AA的共混材料,PVDC嵌入LDPE材料中,相容性明显改善,其缺口冲击强度和断裂伸长率提高,吸油率下降;含20%LLDPE及3%LDPE-g-AA的共混材料,其拉伸强度为14.43 MPa、断裂伸长率为389.11%、缺口冲击强度为29.51 kJ/m2、吸油率为14.40%,力学性能和阻隔性能优良。     

柠檬酸改性对变色聚乙烯醇流延膜性能的影响

以聚乙烯醇（PVA）为母液、柠檬酸为交联剂制备了变色PVA流延膜,并对薄膜的力学性能、光学性能和热稳定性进行了研究。结果表明,随着柠檬酸质量分数的增大,薄膜的抗张强度增大,伸长量减小;随着柠檬酸质量分数的增加,薄膜的雾度呈上升趋势;柠檬酸质量分数对变色薄膜的颜色及颜色变化也有较大影响;添加柠檬酸提高了薄膜的热分解温度,从而提高了薄膜的热稳定性。     

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     

Radiation grafting of hydrophilic monomers onto poly(4-methylpentene-1), II. Grafting of long chain monomers and physical properties of the grafted films

Radiation grafting of 2-hydroxyethyl methacrylate (HEMA) and methoxytetraethyleneglycol methacrylate (M4G) on low crystallinity poly(4-methylpentene-1) (TPX) has been investigated. Grafting yield increased with increasing pre-irradiation dose, grafting temperature, and monomer concentration. Grafting rate depends on length of molecular chain in the monomers and decreases with increasing chain length. The grafting yields of electron beam irradiated samples were higher than those of γ-irradiated ones because of higher radical concentration. Tensile strength of the grafted film in the dried state increased and the elongation at break decreased with increasing degree of grafting. On the other hand, in the wet state, the tensile strength and elongation at break decreased with increasing the degree of grafting due to the lack of hydrogen bonds between the grafted chains caused by increased water absorption.     

HDPE/LLDPE/POE薄膜性能的研究

采用线型低密度聚乙烯（LLDPE）和热塑性弹性体乙烯-辛烯共聚物（POE）对高密度聚乙烯（HDPE）薄膜进行改性,研究了LLDPE和POE对共混体系薄膜力学性能、加工性能的影响,探讨了LLDPE增强HDPE的机理。结果表明,加入一定量LLDPE,使HDPE／LLDPE薄膜的拉伸强度较纯HDPE薄膜有所增加,而单位冲击破损质量则有所下降。当w（LLDPE）为15％时,HDPE／LLDPE薄膜的拉伸强度提高21．6％,薄膜的单位冲击破损质量降低23．0％。在HDPE／LLDPE/POE三元体系中,当w（POE）,w（LLDPE）分别为10％,15％时,薄膜的拉伸强度、单位冲击破损质量、断裂伸长率比纯HDPE薄膜分别提高2．3％,113％。36．0％,综合性能良好。     

线性低密度聚乙烯反应挤出接枝马来酸酐的研究

以过氧化二异丙苯(DCP)为引发剂,在双螺杆挤出机中进行了马来酸酐(MAH)熔融接枝线性低密度聚乙烯(LLDPE)的研究,用红外光谱表征了接枝反应的存在。考察了引发剂用量、单体用量、螺杆转速以及温度对接枝反应的影响,并探讨了苯乙烯(St)作共单体对接枝反应的影响。研究表明:在引发剂含量较低时,用苯乙烯作共单体能够显著提高接枝率。     

Performance improvement of (linear low‐density polyethylene)/poly(vinyl alcohol) blends by in situ silane crosslinking

Linear low‐density polyethylene (LLDPE)/poly(vinyl alcohol) (PVA) blends were prepared by melt mixing. LLDPE/PVA weight ratios between 90/10 and 40/60 were studied. The effects of the silane coupling agent 3‐(trimethoxysilyl)propyl methacrylate on processability, gel fraction, component interaction, compatibility, thermal stability, tensile properties, and morphology of the LLDPE/PVA blends were investigated. The results indicated that the presence of silane increased the equilibrium torque of the LLDPE/PVA blends because of crosslinking and better compatibility between LLDPE and PVA. The degree of crosslinking was quantified by gel fraction measurements, and crosslinking was confirmed by Fourier Transform Infrared Spectroscopy analysis. The melting temperature depression of PVA and LLDPE further suggested the formation of crosslinks. The thermal stability and tensile properties such as tensile strength, elongation at break, and Young's modulus of the blends also increased with the incorporation of silane. Improved compatibility between LLDPE and PVA in the blends with silane was demonstrated by the interconnected rough material observed in scanning electron microscopy images that differed from the morphology of the LLDPE/PVA blends without silane. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

LLDPE/纳米ZnO复合材料的制备与性能研究

将改性纳米ZnO与线型低密度聚乙烯(LLDPE)熔融共混、制备了LLDPE/纳米ZnO复合材料。通过SEM观察纳米ZnO粒子在LLDPE基体中的分散情况;研究了复合材料的力学性能及维卡软化点。结果表明:改性纳米ZnO的加入可提高LLDPE的力学性能和维卡软化点。其中,复合材料的拉伸强度、断裂伸长率、冲击强度、弯曲强度的最大值分别比LLDPE提高了17.00%、13.42%、9.90%、7.04%。     

Use of grafted aspen fibers in thermoplastic composites: IV. Effect of extreme conditions on mechanical properties of polyethylene composites

Hardwood fibers of aspen in the form of chemithermo-mechanical pulp (CTMP) have been used as reinforcement in linear low density polyethylene (LLDPE). The effect of composite treatment (immersion in boiling water, heat exposure at 105°C for seven days or at a temperature of −40°C) on resulting mechanical properties were evaluated. The grafted aspen CTMP composites showed by far the best results with regard to secant modulus, tensile strength, energy, and strain when compared to those of wood flour, mica or glass–fiber filled LLDPE, as well as to virgin LLDPE. Finally, the dimensional stability of CTMP aspen-filled LLDPE composites immersed for four hours in boiling water was better than that of mica or glass–fiber filled LLDPE.     

官能化线性低密度聚乙烯的流变行为及力学性能

利用毛细管流变仪研究了官能化ＬＬＤＰＥ（ＬＬＤＰＥ－ｇ－ＡＡ、ＬＬＤＰＥ－ｇ－ＧＭＡ）的流变行为。结果表明：在高的剪切应力下ＬＬＤＰＥ－ｇ－ＡＡ、ＬＬＤＰＥ－ｇ－ＧＭＡ的表观粘度比纯ＬＬＤＰＥ的小。表明官能化ＬＬＤＰＥ的流动性提高了,其加工性能变好。官能化ＬＬＤＰＥ的表观粘度随接枝单体含量的增加而降低,这说明接枝到ＬＬＤＰＥ分子链土的单体起到了内润滑剂的作用。利用Ｉｎｓｔｒｏｎ１１２１拉力机测试了     

Chemically Induced Graft Copolymerization of Itaconic Acid onto Sisal Fibers

Itaconic acid (IA) was grafted onto sisal fibers using potassium persulfate as initiator. The effect of the monomer, initiator concentration, and reaction temperature on the grafting percentage has been investigated. Evidence of the grafting process has been shown using IR spectroscopy and a scanning electron microscope. The tensile strength and thermogravimetric analyses for ungrafted and grafted samples with various degrees of grafting have also been investigated. The effect of grafting percent on the dyeability of grafted sisal fibers with basic dye has been studied.     

Physical Properties of Polyethylene Modified with Crude Palm Oil

The influence of small amount of crude palm oil (CPO) content on the physical properties of high density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) was investigated. The HDPE and LLDPE containing 2%, 3%, and 5% CPO were prepared in a twin-screw extruder. Then films of 0.2 mm thickness were produced by using blown film technique. The improvement in tensile strength and elongation at break with a concurrent decline in density implied the enhancement in toughness of the polymers by the addition of CPO. A gradual increase in impact strength of HDPE with the CPO content further supported the previous notation. The enhancement in the physical properties in the presence of CPO is believed to be attributed to the increased chain mobility of the polymer along with improved orientation strengthening in HDPE and LLDPE. Evidence from scanning electron micrographs was also used to support this contention. The decline in impact strength of LLDPE with the addition of CPO is associated with the formation of defects in the amorphous phase of LLDPE.