含铁光敏剂在LDPE降解在膜中的应用研究

研究了二烷基二硫代氨基甲酸铁（ＦｅＤＲＣ）复合添加剂对ＬＤＰＥ地膜力学性能、羰基指数和粘均分子量的影响。结果表明，含ＦｅＤＲＣ复合添加剂的可控光降解ＬＤＰＥ地膜在贮存过程中力学性能稳定，曝露后期光降解效果良好。     

二乙基二硫代氨基甲酸铁对聚乙烯光降解性能的影响

借助人工加速光老化试验,通过测定含二乙基二硫代氨基甲酸铁聚乙烯薄膜的断裂伸长率,熔体流动速率,凝胶含量,羰基含量和脆化时间等指标,考察了ＦｅＤＥＣ对聚乙烯光降解性能的影响,证实ＦｅＤＥＣ在光氧化初期起抗氧剂作用,抑制了光氧化交联反应,使聚乙烯出现一个光降解诱导期;而在光氧化后期起光活性剂作用,加速断链反应,从而促进了聚乙烯的光降解,两种作用均与ＦｅＤＥＣ浓度成正比,通过调整ＦｅＤＥＣ用量,可以改变     

光降解剂二乙基二硫代氨基甲酸铁的合成及应用

合成了二乙基二硫代氨基甲酸铁（ＦｅＤＥＣ）,通过人工加速老化和户外铺膜试验,考察了该光降解剂应用于聚乙烯薄膜时的光降解情况。试验证明：ＦｅＤＥＣ是一种具有加速聚乙烯薄膜的光氧化作用,且在光照射初期具有抗氧剂性能,而在光照射后期具有光活性剂性能的光降解剂,两者均与ＦｅＤＥＣ的浓度成正比     

可控光降解塑料光敏剂的合成及光敏化效果的研究

合成了二乙基二硫代氨甲酸铁（ＦｅＤＥＣ）、二丁基二硫代氨基甲酸铁（ＦｅＤＢＣ）、月桂酸共生稀土、硬脂酸铈和硬脂酸铁５种可控光降解塑料光敏剂。采用人工加速老化实验，户外曝晒试验，ＩＲ、ＵＶ及ＴＧ－ＤＴＡ等方法探讨了它们的光敏化效果及其光敏化作用的机理。     

含羧酸铈光敏剂及其配合体系的LDPE地膜的应用

研究了羧酸铈光敏剂及其配合体系的各组分的协同关系和作用，讨论了其与合体系对聚乙烯地膜断裂伸长率，羰基指数和相对分子质量的影响，并进行了农田地膜覆盖应用试验，结果表明，含羧酸铈光敏剂配合体系的聚乙烯地膜具有良好的使用性能和可控光降解性能。     

R 22-R 142b-DMF 体系汽液平衡研究

利用Ｒｏｓｅ－Ｗｉｌｉａｍｓ汽液双循环等压平衡釜测定了二元体系Ｒ１４２ｂ－ＤＭＦ及三元体系Ｒ２２－Ｒ１４２ｂ－ＤＭＦ的汽液平衡数据。并分别用ＵＮＩＦＡＣ模型和ＵＮＩＦＡＣ－ＭＨ８１基团贡献型状态方程作了关联和预测，结果符合得较好。     

甲苯2,4—二氨基甲酸二乙酯的合成

本文报道了从２，４一二硝基甲苯（２，４ＤＮＴ），一氧化碳和乙醇直接合成甲苯２，４一二氨基甲酸二乙酯（ＤＥＴＣ）的Ｐｄ一Ｆｅ催化体系的研究结果。     

二次氮化法制备γ‘—Fe4N超细粉末

以ＦｅＣｌ２．ｎＨ２Ｏ和ＮＨ３为原料，采用一步气相合成法制备了Ｆｅ／Ｎ超细粉末，并研究了二次氮化法制备化铁超细粉末的工艺技术，通过比较实验，证实二次氮化法能够制备单相的γ－Ｆｅ４Ｎ粉末。利用ＸＲＤ、ＴＥＭ、ＸＰＳ和ＶＳＭ实验手段对Ｆｅ／Ｎ和γ’－Ｆｅ４Ｎ粉末的晶态、物相、形貌、成分、粒度和磁性进行了初步表征。     

二次氮化法制备γ′－Fe_4N超细粉末

以ＦｅＣｌ＿２·ｎＨ＿２Ｏ和ＮＨ＿３为原料，采用一步气相合成法制备了Ｆｅ／Ｎ超细粉末，并研究了二次氮化法制备氮化铁超细粉末的工艺技术。通过比较实验，证实二次氮化法能够制备单相的γ′－Ｆｅ＿４Ｎ粉末。利用ＸＲＤ、ＴＥＭ、ＸＰＳ和ＶＳＭ等实验手段对Ｆｅ／Ｎ和γ′－Ｆｅ＿４Ｎ粉末的晶态、物相、形貌、成分、粒度和磁性进行了初步表征。实验结果表明，二次氮化法制得的γ′－Ｆｅ＿４Ｎ为高纯、超细、单相的粉末，并且粉末的饱和磁化率σ＿３和矫顽力Ｈｃ值均优于田中隆夫等人的同类研究结果。     

添加剂对含FeDBC的低密度聚乙烯膜光氧化的影响

本文研究了各种添加剂对含ＦｅＤＢＣ的低密度聚乙烯（ＬＤＰＥ）膜光氧化的影响，并讨论了其作用机理。     

含铁光敏剂在LDPE降解地膜中的应用研究

研究了二烷基二硫代氨基甲酸铁(FeDRC)复合添加剂对LDPE地膜力学性能、羰基指数和粘均分子量的影响。结果表明、含FeDRC复合添加剂的可控光降解LDPE地膜在贮存过程中力学性能稳定,曝露后期光降解效果良好。     

Photodegradation of low-density polyethylene with prooxidant and photocatalyst

Low-density polyethylene (LDPE) composite films with trisilver phosphate (Ag₃PO₄) and cadmium selenide (CdSe) particles as photocatalysts and manganese stearate as prooxidant were prepared. The film samples were irradiated under UV and visible light and their photodegradation were evaluated using Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. The carbonyl index of the photocatalyst containing samples was very higher than the pure irradiated LDPE and even prooxidant containing film. The morphologies of the irradiated composite films were completely changed and had many cavities and cracks. The thermal stability of the composites was very lower than the pure polyethylene. However the crystallinity of the LDPE films with photocatalysts was enhanced contrarily the LDPE film with manganese stearate. Generally the results showed that the combination of the prooxidant with photocatalyst have synergistic effect on the photodegradation of the LDPE and can be used to accelerate the degradation of the polyethylene films.     

Photosensitized degradation of polyolefins. II

The oxydative photodegradation of polyethylene sensitized by aromatically substituted dienes such as 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1,4-diphenyl-1,3-butadiene (DPB) has been investigated. The rate of degradation has been monitored by following the change of the mechanical properties of the polymer during accelerated indoor aging tests. It was found that both additives are efficient sensitizers of the photodegradation of polyethylene. The mechanism of photo-oxidation has been investigated by ESR and IR spectroscopy and it has been interpreted on the basis of a complex mechanism which includes excited singlet oxygen (¹O₂) and the products of photodegradation of the additives. Singlet oxygen, produced by DPB and DPH and/or by impurities present in the polymer, reacts with the additives themselves and, directly, with polyethylene. In turn, the products of photodegradation of the additives react with the polymer via hydrogen atom abstraction, further promoting the photodegradation. Irradiation carried out in absence of air seems to rule out the possibility of direct hydrogen atom abstraction by DPB and DPH.     

Studies on the degradable polyethylenes: Use of coated photodegradants with biopolymers

Three degradable polymer materials such as starch–polyethylene (PE) binary blends, PE containing starch and a photoactivator, and PE containing starch and a photoactivator which was coated with gelatin were prepared and their degrees of photodegradation and/or photodegradation after biodegradation were investigated. The addition of the gelatin-coated ferric salt in PE extended the induction period of degradation and accelerated pho-todegradation after the removal of coating material by biodegradation. This result suggested that the degradation rate of PE could be controlled if more powerful photoactivators and/or coating material are developed and their contents are optimized. © 1996 John Wiley & Sons, Inc.     

塑料地膜的应用及改进

塑料地膜覆盖技术在给农业带来显著经济效益的同时,也对土壤和环境造成了严重污染,采用光降解薄膜是减轻这些污染的有效途径。本文叙述了塑料薄膜对生长作物的作用以及残留薄膜对环境和农业耕作的危害,同时,也对光降解机理、光降解薄膜的生产和应用做了简要介绍。     

Improvement of the Photostability of Low-Density Polyethylene and Ethylene Vinyl Acetate Blends with Nanoclay: Toward Durable Nanocomposites for Potential Application in Greenhouse Cover Films

The effect of three different organomodified nanoclays (Cloisite 20A, Cloisite 30B, and Nanomer I28E) as well as the effect of a compatibilizer (PEgMA) was studied, with the purpose of developing greenhouse cover films based on polyethylene/ethylene vinyl acetate blends. Three organomodified clays were analyzed. The influence of organomodifier clay on film optical, morphology, mechanical, and photo-oxidative degradation properties as well as the effect of incorporation of maleic anhydride-grafted polyethylene as a compatibilizer was studied. The combined effect of these nanoclays with two different UV-oxidative protection systems for polyethylene/ethylene vinyl acetate-nanostructured films was evaluated. Two types of UV stabilizer combination systems were studied; one with a combination of heat and light stabilizers of mixture of antioxidants (phenolic and metal deactivator, Irgatec NC66) with hindered amines, Tinuvin 494AR (designated as system-A) and other with a combination of metal deactivator antioxidant, Irganox MD1024 with hindered amines Tinuvin NOR 371 and benzophenones, Chimasorb 81 (designated as system-B). A strong influence is observed in the use of compatibilizing agent, type, and content of nanoclay in the degree of dispersion as well as in the photo-oxidation behavior. The structure obtained is very dependent on the modified clay used; mostly, intercalated–exfoliated clay structure is produced. The induction period for the photodegradation reaction to start is shorter in the samples with the nanoclay than in the pure polymer. There was a difference in the effectiveness of two stabilizing systems used. It was found a better performance for the stabilizer system-A, regardless of the type of clay used. These greenhouse cover films should allow the pass-through of visible light into the greenhouse during day but restrict the pass-through of the infrared radiation out of the greenhouse during night.     

Study of polyethylene photodegradation in formulations with a system of interacting photostabilizers and antioxidants

The accelerated UV photodegradation process of low-density polyethylene films, formulated with two photostabilizers and two antioxidants, was studied to evaluate the effect of different combinations of UV stabilizers and antioxidants on the overall photodegradation process. An experimental design, consisting of 33 formulations with different additive ratios and a blank, was used to evaluate the performance of the four mixed additives. From each formulation, 200 micron-thick films were produced by the extrusion-blowing process. Samples from these films were submitted to accelerated UV aging, and the polymer degradation was measured by carbonyl group evolution, molecular weight distribution changes, and maximum elongation loss. The effect of the additive combination on the different degradation reactions is discussed qualitatively by using “relative variables” and a triangular diagram. © 1996 John Wiley & Sons, Inc.     

Photochemical degradation of thermoplastics

The general mechanism of polymer photodegradation is outlined, and various aspects are then discussed with reference to polyolefins, particularly polyethylene. It is shown that various impurities accelerate degradation and that carbonyl groups play a complex role in the process. Polyolefins can be stabilised against photodegradation by incorporation of suitable u.v. stabilisers or pigments, and the principles involved, including the synergism between u.v. stabilisers and antioxidants, are discussed.     

Study on the degradation of low‐density polyethylene in the presence of cobalt stearate and benzil

Degradable polymers are in great demand for a variety of applications such as packaging, agriculture, and medicine. Polyolefins blended with photodegradants/biodegradants are potential candidates for replacing the nondegradable thermoplastics in areas where litter abatement poses problems. In the present article, the effect of metallic photoinitiators like cobalt stearate and a combination of metallic/nonmetallic photoinitiators, i.e., a mixture of cobalt stearate and benzil, on the photooxidative degradation of low‐density polyethylene (LDPE) films have been investigated. Attempts have been made to correlate the results as a function of mixed additives. Films of LDPE containing varying amounts of cobalt stearate and a combination of benzil and cobalt stearate were prepared. The photodegradation of these films has been monitored by various techniques like FTIR spectroscopy, differential thermal analysis, and density and viscosity measurements. Cobalt stearate was highly effective in accelerating the photodegradation of LDPE films at low concentrations. The addition of benzil to cobalt stearate decreased the rate of photodegradation compared to cobalt stearate alone. A retarding effect was observed when benzil alone was added to LDPE. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 236–243, 2006