25MeV/u Kr辐照下PET薄膜的损伤机制研究；Damage Mechanism of PET Irradiated by 25 MeV/u Kr Ions

通过25MeV/u86Kr离子辐照叠层结晶聚对苯二甲酸乙二醇酯膜(PET),在不同的电子能损(3.407.25keV/nm)和离子注量(5×10113×1012ions/cm2)辐照条件下,对Kr离子在PET中引起的辐照损伤效应进行了研究。借助傅里叶变换红外光谱分析,通过对样品的红外吸收峰进行扣除基底后的Lorentz拟合,分析了与主要官能团对应的吸收峰强度的变化趋势,研究了化学结构与组分在重离子辐照下的变化规律;利用X射线衍射光谱仪测量,研究了Kr离子在PET潜径迹中引起的非晶化过程,并通过对吸光度和非晶化强度随离子注量的指数衰减规律的分析,获得了不同电子能损离子辐照PET时主要官能团的损伤截面和非晶化截面及对应的潜径迹半径。

Grafting acrylic acid onto polypropylene by reactive extrusion with pre-irradiated PP as initiator

In this paper, the modification of polypropylene (PP) with acrylic acid (AA) by reactive extrusion using pre-irradiated PP (rPP) as initiator was investigated. It was found the relatively high graft degree (Gd) and slight degradation of modified PP was obtained when 20 wt% rPP was used. This result can be explained in terms of effective concentration of free radicals.

Preparation and Characterization of Melt Grafting 2-acrylamido-2-methyl-1-propanesulfonic Acid onto Pre-Irradiated Linear Low Density Polyethylene

Linear low density polyethylene (LLDPE) was functionalized with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) by using -ray pre-irradiation in air in a twin-screw extruder. Fourier-transformed infrared spectroscopy (FT-IR) and electron spectroscopy for chemical analysis (ESCA) were used to characterize the formation of LLDPE-g-AMPS copolymers. The content of AMPS in LLDPE-g-AMPS was determined by using element analysis instrument. The effects of concentrations of monomer, reaction temperature and pre-irradiation dose on degree of grafting were investigated. The critical surface tension of LLDPE-g-AMPS was measured by using contact angle method. The influences of the degree of grafting on crystallization properties were studied by using DSC. Compared with neat LLDPE, the crystallization temperature increased about 4C, and crystallinity decreased with increasing degree of grafting. Crystallization rates of grafted LLDPE were faster than that of plain LLDPE at the same crystallization temperature.

Thermal analysis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) irradiated under vacuum

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was irradiated by Co-60 gamma-rays (doses of 50, 100 and 200kGy) under vacuum. The thermal analysis of control and irradiated PHBV, under vacuum was carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile properties of control and irradiated PHBV were examined by using an Instron tensile testing machine. In the thermal degradation of control and irradiated PHBV, a one-step weight loss was observed. The derivative thermogravimetric curves of control and irradiated PHBV confirmed only one weight-loss step change. The onset degradation temperature (T-o) and the temperature of maximum weight-loss rate (T-p) of control and irradiated PHBV were in line with the heating rate (degreesC min(-1)). T-o and T-p of PHBV decreased with increasing radiation dose at the same heating rate. The DSC results showed that Co-60 gamma-radiation significantly affected the thermal properties of PHBV. With increasing radiation dose, the melting temperature (T-m) of PHBV shifted to a lower value, due to the decrease in crystal size. The tensile strength and fracture strain of the irradiated PHBV decreased, hence indicating an increased brittleness.

Excimer-laser irradiated polyimide films as temperature-sensitive materials

The temperature dependence of the resistivity of KrF laser irradiated polyimide films was studied. In all cases, the resistivity decreased with increasing temperature. The irradiated polyimide film exhibited a typical semiconducting property. This result indicated that the irradiated polyimide films can be used as temperature-sensitive materials. We demonstrated that both the sensitivity and the sensitive temperature range of the irradiated polyimide films can be altered by adjusting laser irradiation parameters. The intrinsic relationship between the temperature coefficient of the resistivity and irradiation condition was interpreted in terms of the microstructural change. The result provided a new insight into the fundamental aspects of laser irradiated polyimide film structure and a method of preparing temperature-sensitive materials. (C) 2000 Elsevier Science B.V. All rights reserved.

Formation of conducting layers on excimer-laser-irradiated polyimide film surfaces

Conducting layers on KrF excimer-laser-irradiated polyimide film surfaces were investigated by XPS, SEM and Fourier transform infrared (FTIR)-Raman spectroscopy, Analysis of polyimide residue after laser irradiation provided valuable insight into the nature of the formation of conducting layers. The subtle different between KrF laser irradiation and the pyrolysis of polyimide was found by comparison of the formation process of conducting layers. A physical picture was presented to describe better the formation of conducting layers. Under KrF laser irradiation, polyimide films underwent thermal decomposition assisted by photoinduced direct bond breaking. Polycrystalline graphite was subsequently formed as the product of the secondary addition reaction of carbon-enriched clusters, Such reaction was supported by the remaining energy on the irradiated polyimide film surface. This result shows that the thermal process played an important role that was not just restricted to the formation of conducting layers, Copyright (C) 2000 John Wiley & Sons, Ltd.

Effect of the fold surface of the lamellae on the behavior of the trapped radicals in irradiated polyamide-1010

Two types of macromolecular free radicals -CH2CONHCHCH2- (a) and -CH2C=O (b) trapped in irradiated Polyamide-1010 (PA1010) and PA1010 filled with neodymium oxide (Nd2O3) were characterized by an ESR approach. It was found out that a was mainly trapped in the fold surface of the lamellae and b in the amorphous phase. This result suggested that trapped radicals mainly existed in the noncrystalline phases. The effect of the fold surface area of the lamellae on the behavior of the trapped radicals are discussed in this article. Whether for the specimens with similar crystallinities but different crystallite sizes or for those with the same concentration of neodymium oxide but different crystallinities, radical a exists dominantly in a specimen with a larger fold surface area of the lamellae. Under a certain circumstance, radical a can transform into radical b for a specimen with a larger fold surface area of the lamellae. It means that the fold surface area of the lamellae plays an important role in the transformation of radical a to b. (C) 1998 John Wiley & Sons, Inc.

Mossbauer spectra of Fe-57 in a thick film of YBa2(Cu0.97Fe0.03)(3)O7-x irradiated by a large dose of gamma-rays

Mossbauer spectra of Fe-57 in a thick film YBa2(Cu0.97Fe0.03)(3)O7-x irradiated by a large dose of gamma-rays from Co-60 have been measured. The variation of the relative intensities of some subspectra of Fe-57 in the. Mossbauer spectra of the thick film YBa2(Cu0.97Fe0.03)(3)O7-x after irradiation can be observed. This variation indicates that the change of the coordination environment around some Fe atoms in the lattice occurs due to irradiation. The relative intensity of subspectrum D1(Fe) at the Cu(1) site decreases and that of subspectrum D4(Fe) at the Cu(1) site increases. This may be because of the possible oxygen atom hopping between the coordination environments of D1(Fe) and D4(Fe) in the lattice caused by irradiation. The effect of irradiation on the coordination environment around the Fe atom at the Cu(2) site is not appreciable. (C) 1997 Elsevier Science B.V.

ESR approach to free radicals trapped in irradiated polyamide-1010

Two types of macromolecular free radicals similar to CH2CONH(C) over dotHCH(2) similar to (a) and similar to CH2(C) over dot = O (b) trapped in irradiated polyamide-1010 (PA1010) and PA1010 filled with neodymium oxide (Nd2O3) were characterized by an ESR approach. It is found that (a) is prevailingly trapped in the fold surface of the lamellae and (b) in the amorphous phase. This result suggests that trapped radicals mainly exist in the non-crystalline phases. The effect of the fold surface area of the lamellae on the behavior of the trapped radicals is discussed in this paper. Whether for the specimens with similar crystallinities, but different crystallite sizes, or for those with the same concentration of neodymium oxide, but different crystallinities, radical (a) exists dominantly in the specimen with a larger fold surface area of the lamellae. Under certain circumstances, radical (a) can transform into radical (b), obviously for a specimen with a larger fold surface area of the lamellae. It means that the fold surface area of the lamellae plays an important role in the transformation of radical (a) to (b). (C) 1997 Elsevier Science Ltd.

Investigation of irradiated PA1010 containing heterogeneous nuclei

This paper deals with radiation effects on PA1010 containing heterogeneous nuclei (Nd2O3). With the help of DSC, WAXD and ESR techniques, the change in the crystallinity and the perfection of the crystal of irradiated PA1010 containing heterogeneous nuclei were studied. Copyright (C) 1996 Elsevier Science Ltd.

Influence of the fold surface of the lamellae on radiation effects - Research on irradiated polyamide-1010 containing heterogeneous nuclei

Irradiated polyamide-1010 (PA1010) and PA1010 containing 0.5% (wt) heterogeneous nuclei were studied by ESR, WAXD, DSC and the determination of gel fractions. The fold surface of the lamellae plays an important role in the effects of radiation on crystalline PA1010. The results show that the direct radiation effects on both samples vary, while after being heated to 220 degrees C, the final radiation effects are identical, regardless of the difference in the amount of the fold surface of the lamellae. The post-radiation effects result predominantly from the fold surface.

RADIATION-INDUCED PHASE-SEPARATION IN IRRADIATED PTFE

The radiation induced phase separation in PTFE as shown by the observation of separation of its melting curves was investigated in this work. The observed phase separation was found to depend on irradiation temperature and explained as being duo to radiation induced increase in disorder of its crystalline region.

RADIATION STABILITY OF PTFE IRRADIATED UNDER VARIOUS CONDITIONS

As a typical example of a polymer degraded by radiation, the radiation stability of PTFE was observed to depend upon irradiation conditions. Increases in irradiation temperature and crystallinity were found to increase its radiation stability whereas increase in the concentration of oxygen in the system over a certain range was observed to have little effect on radiation-induced reactions of PTFE as measured by changes in number-average molecular weight, melting temperature and crystallinity.

CHARACTERIZATION OF GAMMA-IRRADIATED CRYSTALLINE POLYMER .3. THERMAL-BEHAVIOR OF GAMMA-IRRADIATED POLYAMIDE-1010

Thermal behaviour of gamma-irradiated plain PA1010 and PA1010 containing different amounts of difunctional cross-linking agent BMI was investigated. In DSC endo- and exotherm, it was found that during irradiation, the presence of BMI markedly changes the melting and crystallisation characteristics of PA1010. A supposition that the network of BMI-containing specimens is rather loose in structure was proposed to explain the discrepancy in thermal behaviour between these two kinds of specimens. The supposition was further ascertained by the less brittleness in mechanical property of specimens containing BMI. Besides, the complexity of the thermal behaviour of gamma-irradiated PA1010 was discussed and attributed mainly to the increase in sigma-e, the fold surface free energy of chain fold crystals.