Effect of Irradiation Crosslinking on Polyethylene Terephthalate Flame-Retardant Fabric

Irradiation cross-linking of flame-retardant polyethylene terephthalate( FR-PET) fabric with the presence of trimethylolpropane triacrylate( TMPTA) was studied. Thermal gravimetric( TG) analysis,differential scanning calorimetry( DSC) and scanning electron microscopy( SEM) were used to analyze the effects of irradiation crosslinking on structure and property of FR-PET fabric with TMPTA. The cross-linking was promoted by the introduced sensitizer. The gel content was 5.94% at the lower dose of 90 kGy and it arrived at the highest level of 13.01% with the increased doses. There were no melt drips of FR-PET fabric after irradiation cross-linking while the flame retardance disappeared at the time of combustion. The melting temperature of irradiated fabric decreased and TG analysis showed that the onset temperature of degradation of FR-PET fabric and the amount of nonvolatile residue at 800℃ increased as the irradiation dosage increased,but it changed a little compared with the pure FR-PFT fabric. SEM photographs showed that the residue char of irradiated PET fabrics after vertical test remained the intrinsic crossed structure,and the enlarged graph showed that the char was uniformly distributed and it was tight honeycombs structure.

Study on Tribological Properties of Irradiated Crosslinking UHMWPE Nano-Composite

Ultra High Molecular Weight Polyethylene(UHMWPE)has been widely used as a bearing material for artificial joint replacement over forty years.It is usually crosslinked by gamma rays irradiation before its implantation into human body.In this study,UHMWPE and UHMWPE/nano-hydroxyapatite(n-HA)composite were prepared by vacuum hot-pressing method.The prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after irradiation.The effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine(model MM-200)under deionized water lubrication.Micro-morphology of worn surface was observed by metallographic microscope.Contact angle and hardness of the materials were also measured.The results show that contact angle and hardness are changed by filling n-HA and gamma irradiation.Friction coefficient and wear rate under deionized water lubrication are reduced by filling n-HA.While friction coefficient is increased and wear rate is reduced significantly by gamma irradiation.The worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear,and that of n-HA filled material is mainly characterized as abrasive wear.After gamma irradiation,the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly reduced.Unfilled and filled materials after irradiation are mainly shown as slight fatigue wear.The results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.

Preparation and adsorption behavior for metal ions and humic acid of chitosan derivatives crosslinked by irradiation

Th/s article deals with the determination of the adsorption properties of metal ions and humic acid in wa- ter on crosslinked chitosan derivatives (carboxymethylchitosan) which were formed using the irradiation technique without any additives.The solubility test of these crosslinked materials were investigated in acidic,alkaline media, distilled water,and certain organic solvents.Scanning electron microscopic (SEM) images showed that the crosslinked chitosan derivatives possessed a porous morphological structure.Charged characteristic analyses demon- strated typically pH-dependent properties of the crosslinked materials.The adsorption studies were carried out by the batch method at room temperature.Adsorption of heavy metal ions (such as Cu^(2+),Cd^(2+)) and humic acid onto crosslinked samples was found to be strongly pH-dependent.Adsorption kinetic studies indicated the rapid removal of metal ions,and humic acid from the aqueous solutions.Moreover,isothermal adsorption data revealed that Cu^(2+),Cd^(2+), and humic acid were removed by these crosslinked materials with high efficiency.Adsorption isothermal data were interpreted well by the Langmuir equation.These crosslinked carboxymethylated chitosan derivatives indicate favor- able adsorption of metal ions and humic acid.

EFFECTS OF ORGANIC COLORANTS ON PHOTO-INITIATED CROSSLINKING AND PHOTO-OXIDATION DEGRADATION OF POLYETHYLENE AND RELATED MECHANISM

The effects of three organic colorants on photo-initiated crosslinking and photo-oxidation degradation of polyethylene (PE) samples irradiated by microwave excited (MWE) UV lamp in the melt and the related mechanism have been studied by gel content and thermal extension rate determinations,X-ray photoelectron spectroscopy (XPS),mechanical property tests,UV spectroscopy,and light microscope.The data from the gel content and thermal extension rate determinations of photo-crosslinked polyethylene (XLPE) sample...

EFFECT OF IRRADIATION TEMPERATURE ON GENERAL EQUATION OF SOL FRACTION-DOSE RELATIONSHIP FOR FLUOROPOLYMERS

In this paper, the effect of irradiation temperature on sol fraction-dose relationship of tluoropolymers was studied. It was found that the increasing of irradiation temperature can result in the decreasing of β value of fluoropolymer, which increases the crosslinking probability of fluoropolymer. The relationship between crosslinking parameter β and irradiation temperature (T_i)of fluoropolymer is established as follows:β=2.2×10^(-3) T_g+4×10^(-4)(T_g-T_i)+0.206.values of some tluoropolymers calculated from the above expression are in agreement with the experimental values.

Effect of irradiation on temperature performance of dispersioncompensation no-core cascade optical-fiber sensor coated with polydimethylsiloxane film

A temperature measurement device can produce data deviations and can even be damaged in a high-dose radiation environment.To reduce the radiation damage to such a device and improve the temperature measurement accuracy in a radiation environment,a temperature sensor based on optical-fiber sensing technology is proposed.This sensor has a cascade structure composed of a single-mode fiber(SMF),a dispersion-compensation fiber(DCF),a nocore fiber(NCF),and another SMF(SDNS).The DCF and NCF are coated with a polydimethylsiloxane(PDMS)film,which is a heat-sensitive material with high thermal optical and thermal expansion coefficients.In experiments,PDMS was found to produce an irradiation crosslinking effect after irradiation,which improved the temperature sensitivity of the SDNS sensor.The experimental results showed that within a range of 30–100℃,the maximum temperature sensitivity after irradiation was 62.86 pm/℃,and the maximum transmission sensitivity after irradiation was 3.353×10^(-2)dB/℃,which were 1.22 times and 2.267 times the values before irradiation,respectively.In addition,repeated temperature experiments verified that the SDNS sensor coated with the PDMS film had excellent temperature repeatability.Furthermore,it was found that with an increase in the irradiation intensity,the irradiation crosslinking degree of PDMS increased,and the temperature sensitivity of the sensor was improved.The proposed sensor could potentially be applied to temperature measurement in a nuclear-radiation environment.

CHARACTERIZATION OF γ-IRRADIATED CRYSTALLINE POLYMERS Ⅱ ISOTHERMAL CRYSTALLIZATION KINETICS OF γ-RADIATION INDUCED CROSSLINKED POLYAMIDE 1010

Polyamide 1010 is a γ-radiation crosslinkable polymer. After irradiation, it is possible to raise its service temperature up to 240℃ . Network formation greatly changes the crystallization behaviour of the polymer. In the present work, DSC was used to examine its isothermal crystallization kinetics. It is found that in addition to the necessity of more undercooling and the lowering of crystallization rate, the primary crystallization stage of the irradiated polymer is shortened. This effect is more evident with increasing radiation dose and content of enhanced difunctionai erosslinking agent. However, the crystallization mechanism of the primary stage is not changed as evidenced by the constancy of Avrami exponent. The lamella end surface free energy σ_e calculated according to Hoffman's equation is very sensitive to γ-radiation. It increases abruptly in 2—3 fold even though the radiation dose is not high enough. The origin of this phenomenon may be accounted for in terms of network structure of the polymer.

Improvement of poly(vinyl alcohol)/poly(vinylpyrrolidone) blended hydrogel by radiation crosslinking

A series of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) blended hydrogel with kappa-carrageenan (KC) were prepared by radiation crosslinking with electron beam to improve the properties of hydrogel as wound dressing. The properties of the blended hydrogels were evaluated in terms of gel fraction, swelling behavior, gel strength and water evaporation from hydrogel. Gel fraction of PVA/PVP was saturated at 50 kGy and the achievcd gel fraction was 70%～80%. However, obtained hydrogel was very fragile and produced many bubbles at a dose of 50kGy and above, hence 1%～5% KC were added to give toughness. The rate of gel formation and the toughness of the blended hydrogel were raised after mixing KC. The PVA/PVP/KC blended hydrogel irradiated showed satisfactory properties for wound dressing, it did not produce bubble during irradiation, and it could retard the water evaporation.

4D打印形状记忆交联聚乙烯的制备与性能

4D打印可实现打印结构的智能动态变形,在航空航天、生物医疗、智能机器人等领域有着巨大的应用前景,文中开发了一种利用熔融沉积(FDM)打印形状记忆交联聚乙烯的新方法。将低密度聚乙烯(LDPE)制备成直径2.85 mm的丝材并进行FDM打印,打印试样经辐照交联后获得形状记忆性能,研究了打印工艺及辐照剂量对打印试样力学性能及形状记忆性能的影响。结果表明,最佳打印温度为180~240℃、最佳打印速度为15~20mm/s。辐照交联后,打印试样拉伸强度增大,断裂伸长率减小;随着辐照剂量从40kGy增大到120kGy,打印试样的凝胶含量和形状固定率分别由50%和95.71%增大到83%和99.47%,形状回复率由113.61%趋近于100%;辐照剂量为100 kGy的打印试样经多次形状记忆循环测试,仍能保持99.29%以上的形状回复率和98.58%以上的形状固定率,表现出非常优异的形状记忆性能。

苯基硅橡胶高剂量辐射老化性能研究

该研究采用不同剂量的伽马射线对苯基硅橡胶样品进行辐照老化实验。对样品的力学强度、硬度、回弹性和交联度等宏观性能进行了研究,并通过热失重仪和红外光谱仪对样品的热稳定性和分子结构进行了分析。力学性能测试结果显示,辐照剂量不超过500kGy时,样品的断裂伸长率明显下降,从482%降至65%;而拉伸强度在辐照剂量超过1000kGy后才有明显减小,从6.2MPa降至0MPa;回弹率和硬度随着辐照剂量增加而增加,但当剂量超过2000kGy后开始减弱。凝胶含量和热失重实验结果显示,低剂量辐照会提高样品的交联度,从94%增加至97%;而辐照剂量超过1000kGy后交联度变化较小,同时样品的热稳定性得到提升。红外光谱分析显示,在低剂量下,样品的侧链易受氧化而发生断裂,而在高剂量下,主链破坏时产生的少量大分子会重新交联侧链。

辐照交联陶瓷化硅橡胶复合带制备工艺的研究

本课题主要攻克陶瓷化硅橡胶复合带的辐射加工工艺,将完成陶瓷化硅橡胶的制备工艺研究、陶瓷化硅橡胶-云母带-自粘性硅橡胶的复合工艺的研究、陶瓷化硅橡胶复合带的辐照交联工艺的研究。确立陶瓷化硅橡胶的成瓷理论,建立化学组成-陶瓷化结构-性能关系,掌握高品质陶瓷化硅橡胶复合带的制备工艺。

辐照剂量和交联敏化剂对IXPE性能的影响

探索了辐照剂量和交联敏化剂(TAIC)用量对交联聚乙烯发泡材料性能的影响,对辐射交联聚乙烯发泡材料(IXPE)的力学性能、泡孔形态和凝胶含量等进行了分析。结果表明,IXPE的交联程度随辐照剂量和TAIC用量的增加而增加,凝胶含量为70%~91%时,母片发泡状态良好。TAIC的加入虽然有助于LDPE交联程度的提高,但不利于IXPE保持其柔软性。辐照剂量为80~100 kGy时,IXPE的综合力学性能最好。SEM结果显示辐照剂量在100 kGy以内时,IXPE内部泡孔的尺寸较大,均匀性较好。辐照剂量为120 kGy时,在大泡孔周围开始出现小泡孔。随着TAIC用量的增加,IXPE内部泡孔尺寸逐渐减小并开始变得不均匀,出现了大量串孔现象。

聚乙烯辐照交联的研究进展

简要介绍了辐照交联基本反应及原理，评述了在辐照作用下聚乙烯结构尤其是结晶形态的变化，讨论了辐照交联对聚乙烯机械力学性能的影响，并展望了辐照交联聚乙烯研究及应用前景。

聚碳硅烷强化辐射交联的研究

合成了不同乙烯基含量的聚碳硅烷 ,研究了其 He气氛条件下的电子束辐射交联不熔化处理 ,分析了含乙烯基聚碳硅烷纤维在辐照过程中的结构变化。结果表明 ,乙烯基起到强化聚碳硅烷辐射交联的作用 。

模板法微波辐射下交联壳聚糖的合成及其吸附性能

采用微波辐射技术、得到以Zn2+为模板的交联壳聚糖,考察了微波法制备工艺、产物的吸附量变化以及吸附动力学。结果表明,与传统制备法相比,微波模板法合成交联壳聚糖工艺简单,产物的吸附量大,明显缩短了反应时间,而且交联物具有一定记忆性及选择性。

γ射线辐照处理对聚丙烯腈纤维预氧化反应的影响

利用γ射线在真空下对聚丙烯腈(PAN)原丝进行辐照处理,研究辐照处理对其预氧化反应的影响。通过凝胶含量测定表明,PAN纤维主要发生交联,200 k Gy时凝胶含量达到80%。联合差示扫描量热仪和傅里叶变换红外光谱仪考察辐照交联对PAN纤维预氧化过程的影响,并考察不同预氧化程度PAN纤维的力学性能。研究结果表明,γ射线辐照处理能有效降低PAN纤维预氧化反应的起始温度(~30℃),显著缓和预氧化过程的放热行为;同时,辐照处理还可有效降低预氧化温度,加速预氧化进程。

微波辐射下交联壳聚糖微球的制备及吸附性能研究

微波辐射下,以壳聚糖为原料,甲醛为预交联剂,环氧氯丙烷为交联剂,制得甲醛环氧氯丙烷交联壳聚糖微球树脂,研究了合成条件对微球吸附性能的影响,并采用傅里叶红外光谱仪和电子扫描电镜对树脂的微观结构和形貌进行表征。结果表明,树脂具有很好的球形;Shiff碱反应能够很好地保护壳聚糖上的氨基;交联剂用量、搅拌速率和酸处理条件对树脂的吸附性能的影响较大。当合成条件为搅拌速率600r/min、甲醛1.5mL、环氧氯丙烷3mL、酸化时间8min、盐酸用量30mL,所得交联壳聚糖微球对Cu(Ⅱ)的吸附容量可达到269.83mg/g。

聚琥珀酸丁二酯的辐射交联及其生物降解性

对聚琥珀酸丁二酯 (PBS1)采用两步法辐照 ,比其它辐照法得到的凝胶含量高 ,这是由于在室温下预先辐射所形成的交联网络结构减少了聚合物的降解。交联后的PBS1有较高的耐热变形性。通过酶降解试验和土埋法降解实验 ,PBS1有很高的生物降解性 ,即使它产生了很高的交联结构。在 6 5℃时 ,酶的降解率最高。由于交联样品所含有的交联网络结构阻碍它的降解 ,交联PBS1的生物降解失重低于未交联样品。

γ射线辐射对木材构造和材性的影响

该文在归纳高能射线的种类和高能射线辐射对木材作用机理的基础上 ,详细地归纳了高能射线 ,特别是γ射线辐射对木材构造和木材化学、物理、力学性质的影响 .本质上 ,当射线辐射剂量较高时 ,将引起木材细胞壁结晶度降低 ,细胞壁主成分分子链切断 ;当射线辐射剂量较低时 ,可能导致细胞壁主成分产生交联 .在此基础上 。

γ辐照交联聚乙烯绝缘电缆水树行为的研究

核电站的控制系统等需要大量的电线电缆，这些电缆的耐辐射性能至关重要。高能辐射对固态聚合物有多种作用，包括引发交联以及链裂解等。水树是影响交联聚乙烯电缆，特别是中低压电缆使用寿命的重要因素。本文研究了γ辐射对交联聚乙烯电缆绝缘水树行为的影响。结果显示，在0～3000kGy辐照剂量之内，水树的长度与密度随着辐照剂量的增加而增加。