新型光降解体系对光/生物降解薄膜光降解行为的影响

研究了由光敏剂硬脂酸铁和抗氧剂 10 76组成的光降解体系的光 /生物双降解聚乙烯薄膜在紫外灯辐照下的断裂伸长率保留率、分子量、脆化期、诱导期等的变化规律。结果表明 ,硬脂酸铁具有促进光降解和抑制交联的双重作用 ;抗氧剂 10 76对薄膜光降解作用的影响没有硬脂酸铁显著 ;由它们组成的光降解体系具有较好的时控光降解效应 ,能使薄膜诱导期在较大时间范围内调控     

光/生物双降解薄膜的降解性能研究

研究了由光敏剂硬脂酸铁和抗氧剂1076组成的光降解体系的光/生物双降解聚乙烯薄膜在紫外灯辐照下的分子量、脆化期、诱导期、生物降解性能等的变化规律,并用红外光谱仪表征了塑料膜的化学结构变化,用电子显微镜观察了薄膜表面的微生物生长丰度.结果表明硬脂酸铁具有促进光降解和抑制交联的双重作用;抗氧剂1076具有较强的抑制光降解作用;硬脂酸铁和抗氧剂1076对诱导期的影响均比脆化期强;由它们组成的光降解体系经过光照后具有较强的生物降解性能.     

光降解聚乙烯薄膜的研究

研究了用过渡金属有机化合物作光敏剂的添加型光降解聚乙烯薄膜的光降解行为，介绍了光敏剂的品种及用量，并探讨了光照条件下薄膜光降解的速度及薄膜光降解过程中聚乙烯的化学结构，分子量分布等结构参数和力学性能的变化。     

可控光降解聚乙烯薄膜的研究

制备了硬脂酸铈（CeSt4）光敏剂。采用自制的CeSt4与硬脂酸锌（ZnSt2）、硬脂酸钙（CaSt2）、纳米二氧化钛（TiO2）等配合剂,制备出一种添加型的可控光降解聚乙烯（LDPE）薄膜。用红外光谱、粘均法测分子量和DSC等方法,对老化后的LDPE薄膜样品进行了表征。试验结果表明：CeSt4是一种很好的光敏剂;ZnSt2和CaSt2是有效的光降解促进剂,可缩短LDPE薄膜的光降解诱导期;改性纳米TiO2可延长LDPE薄膜光降解诱导期。     

抗氧剂对聚乙烯光降解膜结构及性能的影响

采用紫外光加速老化的方法研究了抗氧剂1010对聚乙烯(PE)光降解膜的影响,并通过红外光谱、紫外光谱分析和拉伸性能测试对老化前后的薄膜的结构和性能进行了研究。结果表明,抗氧剂1010能抑制PE的光氧化降解,且导致薄膜光降解过程中羰基化合物的生成量和类型减少;添加抗氧剂1010的光降解薄膜降解的诱导期延长,PE光降解膜紫外照射3 d后其断裂伸长保留率小于80 %,而添加0.3 %（质量分数,下同）抗氧剂1010的PE光降解膜照射4~5 d后其断裂伸长保留率小于80 %。     

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     

聚乙烯中抗氧剂的性能

本文研究了在聚乙烯热老化过程中,抗剂[4、4′-硫化双(3甲基——6特丁基苯酸)]的浓度和聚乙烯氧化诱导期的变化。浓度的降低遵循一级动力学。诱导期仅与抗氧剂的浓度有关,与老化条件无关。在聚乙烯熔融温度以上或以下范围内,浓度小的速率常数的Arrhenius图线是线性的,并求得了活化能。浓度降低的主要因素是抗氧剂从试样表面挥发,并求得溶解在聚乙烯中的抗氧剂的挥发速度常数。     

抗氧剂含量对交联聚乙烯热氧老化性能的影响

将受阻酚类抗氧剂4,4'-硫代双(6-叔丁基间甲酚)与低密度聚乙烯(LDPE)、交联剂DCP(过氧化二异丙苯)进行熔融共混,制备了一系列不同抗氧剂含量的交联聚乙烯(XLPE).研究了抗氧剂含量对XLPE交联过程、凝胶含量、氧化诱导期(OIT)、热老化前后力学性能及热延伸特性的影响.研究结果表明,添加抗氧剂可以延迟交联反...     

新型添加型光敏剂芳基三唑制备光降解塑料及性能研究

利用芳基三唑分子吸收辐射能产生电子跃迁的能力,制备了一种光可降解的低密度聚乙烯(LDPE)。利用扫描电镜观察了有无添加光敏剂以及光照后的塑料薄膜的微观结构;利用傅里叶红外光谱仪表征了光降解前后,LDPE的光能团特性;利用紫外可见光谱测定了添加光敏剂前后薄膜的吸光度,并测定了其基本的力学性能。结果表明:芳基三唑光敏剂可明显促进LDPE的光降解速率,重均分子量下降了24.72%。     

新型芳胺类抗氧剂与聚乙烯相容性研究

采用傅里叶红外光谱(FTIR)和氧化诱导期(OIT)对芳胺类抗氧剂与聚乙烯材料的相容作用进行研究。实验结果表明:随着温度的升高,抗氧剂与聚乙烯材料的相容量增加,其中防老剂D与聚乙烯材料的相容量增加最大。抗氧剂浓度对其与聚乙烯材料的相容作用几乎无影响。随着实验时间的延长,抗氧剂与聚乙烯材料的相容量增加,其中新型芳胺抗氧剂的相容速率最慢,但相容性最好。     

Photobiodegradation of low‐density polyethylene/banana starch films

The effects of the starch content, photosensitizer content, and compatibilizer on the photobiodegradability of low‐density polyethylene (LDPE) and banana starch polymer blend films were investigated. The compatibilizer and photosensitizer used in the films were PE‐graft‐maleic anhydride (PE‐g‐MA) and benzophenone, respectively. Dried banana starch at 0–20% (w/w) of LDPE, benzophenone at 0–1% (w/w) of LDPE, and PE‐g‐MA at 10% (w/w) of banana starch were added to LDPE. The photodegradation of the blend films was performed with outdoor exposure. The progress of the photodegradation was followed by determining the carbonyl index derived from Fourier transform IR measurements and the changes in tensile properties. Biodegradation of the blend films was investigated by a soil burial test. The biodegradation process was followed by measuring the changes in the physical appearance, weight loss, and tensile properties of the films. The results showed that both photo‐ and biodegradation rates increased with increasing amounts of banana starch, whereas the tensile properties of the films decreased. The blends with higher amounts of benzophenone showed higher rates of photodegradation, although their biodegradation rates were reduced with an increase in benzophenone content. The addition of PE‐g‐MA into polymer blends led to an increase in the tensile properties whereas the photobiodegradation was slightly decreased compared to the films without PE‐g‐MA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2725–2736, 2006     

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.     

Cinnamylidene-amine-sensitized photodegradation of polyethylene

The activity of Schiff's bases of cinnamic aldehyde and aromatic amines in the controlled photodegradation of polyethylene (PE) was studied. N-cinnamylidene anilines containing different substituents in the amine ring (methyl group, halogen, or amine group) and N-cinnamylidene α-naphthyl amine were synthesized and introduced into the polyethylene films by compression molding or extrusion, and they were exposed to the filtered ultraviolet light produced by mercury lamp. The changes in molecular weight, tensile strength, and characteristic IR absorptions were followed during irradiation to control the processes undergoing in the polymer films. It was discovered that N-cinnamylidene anilines containing methyl or halogen substituents and N-cinnamylidene α-naphthyl amine accelerated the photodegradation of polyethylene. Their sensitizing activity increased when the mixtures of Schiff's bases and stannous laurate were introduced into the polymer. PE films containing these additives became brittle after 600 h exposure to the artificial UV light which was the equivalent of 1.5–2 years exposure to the natural sunlight in the medium geographic latitudes. The mechanism of the initial step of photodegradation is discussed.     

THERMAL OXIDATION OF POLYMER BLENDS CONTAINING AN ANTIOXIDANT

Thermal oxidation of blends of polystyrene and poly(vinyl methyl ether) containing a hindered phenol as antioxidant was studied at 110^°C. The incorporation of the antioxidant in the miscible blend lengthens the induction period and lowers the rate of oxidation. Phase separation which preceded the end of the induction period caused the antioxidant to redistribute itself among the different phases. This in turn controlled the induction period and the oxidation rate. The molecular weight of the PVME component in the blend remained unchanged during the induction period but decreased rapidly afterwards. Polystyrene also underwent chain scission after the end of the induction period. When low molecular weight polystyrene was blended with PVME, the films remained homogeneous throughout the oxidation reaction. This resulted in a further increase in the induction period and decrease in the rate of oxidation.     

聚乙烯原料对高密度聚乙烯土工膜性能的影响

本实验采用吹塑成型工艺,以不同牌号的聚乙烯(PE)树脂为原料生产2 mm厚度双光面高密度聚乙烯(HDPE)土工膜,研究PE原料对HDPE土工膜性能的影响。结果表明:中密度聚乙烯(MDPE)土工膜综合性能优异,主要是由其特有的分子结构(如分子量分布双峰性、α烯烃长支链)所决定的;不同PE原料氧化诱导时间不同,可通过调节含抗氧剂色母料(或抗氧剂)的含量,使HDPE土工膜氧化诱导时间达到要求;HDPE土工膜在焊接时应根据PE材质的不同而选择不同的焊接条件。     

农药在水体中光化学降解研究进展

农药在水中的光化学降解是重要的降解途径,其过程和产物对农药药效、代谢、毒性及环境影响很大。综述了影响水体中农药光解的不同因素,包括光源、pH、光敏剂、光猝灭剂等,分析了农药在水体中光解产物的分离和鉴定,并讨论了水中农药光解的意义。     

Effect of polymer chain scission on photodegradation behavior of polystyrene/multi‐wall carbon nanotube composite

To clarify an effect of polymer chain scission on a polystyrene (PS)/multi‐wall carbon nanotube (MWNT) composite photodegradation, a relationship between the change of molecular weight and photodegradation behavior was studied. The MWNT loading brought about severe PS chain scission and led to the increase of the low molecular weight (less than 10⁵) fraction. The increase of the fraction was not proportional to the loading amount and showed the minimum at the 2% loading. The strange behavior was due to a rheological effect bringing about a decrease of shear stress in the composite preparation. An unsaturated end group was produced by the chain scission and became the photodegradation initiator leading to auto‐oxidation and crosslink reactions. The MWNT scavenged radical species and worked as an antioxidant. The coexistence of the unsaturated end group and MWNT made the photodegradation behavior complicated. However, the MWNT radical scavenging ability was considerably poor, and the MWNT had little ability to inhibit the photodegradation initiation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40362.     

The effect of antioxidants in the autoxidation of methyl conjugatedcis,trans-octadecadienoates

The effect of antioxidants on the autoxidation of methyl conjugatedcis,trans-octadecadienoates was evaluated by estimating the induction period by measuring the increase in weight with time. Peroxide values and molecular weights were also used to determine extent of oxidation. UV and IR absorption were measured to determine conjugated dienes and isolatedtrans double bonds. Antioxidants, such as butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), propyl gallate (PG) and sesamol, lengthened the induction period as much as seven to twelve times. After autoxidation to a weight gain of 10 mg per 1.5 g, the antioxidant containing samples had higher molecular weights and lower diene contents than the control samples. The induction periods were shorter, the peroxide values lower with or without antioxidants for the conjugated dienoates than for the nonconjugated dienoates. Effect of antioxidants might be explained by the formation of a hydrogen bond of the hydroxyl of the antioxidant and π-electrons as well as the inhibition of the chain-reaction.