辐射硫化对三元乙丙橡胶力学性能的影响

以三元乙丙橡胶(Ethylene propylene dine terpolymer rubber,EPDM)为基材,三羟甲基丙烷三甲基丙烯酸酯(Trimethylopropane trimethylacrylate,TMPTMA)为交联敏化剂,采用60Co对其进行辐射硫化。研究了不同吸收剂量、不同TMPTMA用量对EPDM的凝胶分数和力学性能的影响,并通过热空气老化测试和热重分析,研究了辐射硫化橡胶与化学硫化橡胶耐老化性和热稳定性。结果表明:随着TMPTMA用量的增加,EPDM的凝胶分数增加,适宜用量为EPDM质量的8%。吸收剂量在120 kGy以下时,拉伸强度、伸长率为100%时的弹性模量及邵氏A硬度随着剂量的增加而增加,而断裂伸长率减小,合适的吸收剂量为约80 kGy。热空气老化后,化学硫化橡胶的拉伸强度及断裂伸长率迅速下降,而辐射硫化橡胶的拉伸强度先增加后减小,断裂伸长率缓慢降低。热重分析结果显示,化学交联的EPDM在430℃-480℃发生热分解,辐射硫化交联的EPDM的热分解温度为480℃-530℃。这些结果表明辐射硫化橡胶比化学硫化橡胶的耐老化性能和热稳定性好。     

全钢载重子午线轮胎过渡层的辐射预硫化及组胎后性能研究

以天然橡胶为基材作为全钢载重子午线轮胎的过渡层,在0 60 kGy吸收剂量范围内,采用电子束辐照技术对其进行辐射预硫化研究,结果表明,过渡层的格林强度随吸收剂量增加,吸收剂量60 kGy时,胶料的格林强度增幅可达300%;低吸收剂量时,胶料的粘度增加较快,之后吸收剂量虽有增加,但粘度变化不大;辐射预硫化与未辐射预硫化的过渡层相比,热硫化后的力学性能相差不大;过渡层减薄1 mm后,单胎质量平均减少1.5 kg而不影响轮胎的主要性能。     

高能电子束辐射交联丁腈橡胶/聚氯乙烯胶辊生胶

分别采用高能电子束辐射(EB)以及传统硫磺硫化制备丁腈/聚氯乙烯硫化胶,研究了吸收剂量对硫化胶性能、结构的影响,以及两种硫化工艺制得的硫化胶各项性能及结构间的差异.实验结果表明:EB硫化中,随着吸收剂量增大,硫化胶交联程度提高,断裂截面更加平滑,玻璃化转变温度向高温区移动,结晶度提高,且当吸收剂量为150 kGy时,硫...     

辐照乙烯-四氟乙烯共聚物的热老化性能

对吸收剂量为60 kGy、120 kGy和180 kGy的乙烯-四氟乙烯共聚物(ETFE)样品进行270℃热老化处理,通过残炭率、热延伸、拉伸性能、体积电阻率和傅里叶变换红外光谱(FTIR)对热老化不同时间的样品进行测试和表征。结果表明:随着吸收剂量的增大,样品残炭率逐渐增大,热延伸逐渐减小,断裂拉伸应变呈现下降趋势,吸收剂量为120 kGy时,材料交联度最高;随着热老化时间延长,样品的拉伸强度和断裂拉伸应变均呈下降趋势,体积电阻率也呈下降趋势,在吸收剂量为120 kGy时ETFE体积电阻率最高,绝缘性能最优;FTIR表明辐射交联ETFE材料的非晶组分随热老化时间延长而先增加后降低。     

双酚A型环氧树脂的1.5 MeV电子束辐照效应

本工作以双酚A型环氧树脂为研究对象,在1.5 MeV电子加速器下分别以18 kGy/h和2 250 kGy/h的剂量率对其进行辐照处理,以达到总吸收剂量135 kGy、270 kGy、500 kGy和1 000 kGy。系统研究了两种不同剂量率和不同吸收剂量对环氧树脂表面形貌、化学结构和热性能的影响。结果表明：电子束辐照环氧树脂时,高剂量率下环氧树脂内部会产生脉状裂纹,而总吸收剂量对树脂的热稳定性和力学性能影响较大;环氧树脂经电子束辐照后,玻璃化转变温度和交联密度下降,同时力学性能下降,表明辐射裂解占主导;电子顺磁共振光谱测试表明辐照过程中有烷基自由基和过氧自由基的产生,自由基浓度与吸收剂量呈正相关性。进一步研究了自由基在空气中的稳定性,随着存放时间的增加,自由基浓度最终趋于稳定。     

高回弹氢化丁腈橡胶的γ辐射硫化与性能研究

为提高氢化丁腈橡胶(HNBR)在热环境中和高压条件下的使用稳定性和使用寿命,本文通过γ辐射工艺制备辐射硫化的HNBR,研究辐射硫化的吸收剂量对材料微观形态、力学性能、热稳定性、耐热油老化和耐热空气老化性能的影响。通过扫描电镜(SEM)观察HNBR断裂面,发现辐射硫化的HNBR样品断面更光滑,其硫化效果优于热硫化。随着吸收剂量增加,样品的力学性能和耐老化性能显著提高,在150℃的903#标准油中浸泡70 h,与热硫化HNBR相比,辐射硫化HNBR体积变化率更低。当吸收剂量为160 kGy时,辐射硫化HNBR的体积变化为18.3%。热空气老化后,样品随着吸收剂量增加,力学性能下降量减少。优异的耐热油老化和耐热空气老化性能使辐射硫化HNBR有更强的密封性能。     

硅橡胶膜辐射接枝中酸效应的研究——Ⅰ.与丙烯酸共辐射接枝反应

本文以硅橡胶为基材深入研究了与丙烯酸共辐射接校中的酸效应。结果表明,甲醇-丙烯酸与硅橡胶共辐射接枝体系中酸效应在不同吸收剂量范围是不同的。<5kGy时酸有敏化作用,在5—13kGy范围酸有相反的效果。在所有剂量范围内单体浓度、剂量率等因素对辐射接枝反应的酸效应无明显影响。除吸收剂量外,酸效应还与基材组成、单体与溶剂类型以及接枝方法等多种因素有关。     

γ辐照羧基丁苯胶乳的研究

研究了以丙烯酸－2－乙基己酯（2－EHA）为交联酶化剂，γ辐照对羧基丁苯胶乳（CS－BRL）的交联行为，粒径大小、分布以及化学结构和热性能的影响，并推测了CSBRL辐射硫化的反应机理，结果表明，一率对CSBRL的交联行为影响不大；随着吸收剂量增大，交联密度急剧增大，体积溶胀度迅速减小，交联点间平均分子量减小，交联密度还随着敏化剂用量增加而增大。动态光散射仪的测试表明，吸收剂量＜25kGy时，胶乳的流体力学半径与辐照前相比变化不大，当吸收剂量增大到102kGy时，流体力学半径与辐照前相比稍有增加。显微傅立叶红外光谱证实CS－BRL不仅被辐射交联，还接枝上了丙烯酸酯，DSC分析表明，未加敏化剂的CSBRL玻璃化温度随剂量增加变化不大，而加入3％敏化剂的CSBRL的DSC曲线变化很大。     

甲基丙烯酸缩水甘油酯改性氮化硼纳米片掺杂环氧树脂及其耐辐射性能

环氧树脂（EP）具有良好的机械和绝缘性能,被广泛地应用于航空航天和核工业领域,但其在高能辐射环境中容易降解失效。氮化硼（BN）具有优异的辐射稳定性,但其与高分子基体较差的相容性限制了性能发挥。本工作利用γ辐射对氮化硼纳米片（BNNSs）进行改性,制备出与EP具有良好相容性的甲基丙烯酸缩水甘油酯（GMA）改性的氮化硼纳米片（BNNSs@PGMA）,并通过溶液共混,将其引入环氧树脂基体中,制备出EP、BNNSs/EP、BNNSs@PGMA/EP复合材料,同时研究了γ射线辐照前后复合材料性能的变化。结果表明：环氧树脂复合材料的拉伸强度随着吸收剂量的增大呈现先增大后减小的趋势;吸收剂量小于400 kGy时,辐射交联占据主导作用,400～1 000 kGy吸收剂量下主要是辐射降解占据主导作用;吸收剂量1 000 kGy时,EP的拉伸强度下降了42.9%,而BNNSs@PGMA/EP的拉伸强度仅下降了21.3%,表现出优异的耐辐射性能。提高BNNSs@PGMA的改性率可以增强复合材料的耐辐射性能。     

γ辐射对氮化硼/环氧树脂复合材料性能的影响

环氧树脂及其复合材料具有良好的电气绝缘性能,在核工业领域得到了广泛应用。本工作将六方氮化硼粉末(h-BN)与四氢邻苯二甲酸二缩水甘油酯、固化剂甲基四氢邻苯二甲酸酐和促进剂2,4,6-三(二甲氨基甲基)苯酚共混,并热固化成型,制备了氮化硼/环氧树脂(h-BN/EP)复合材料。在空气和通氮限氧气氛及一定吸收剂量率下(60 Gy/min),研究了h-BN粉末和h-BN/EP复合材料经60Coγ射线辐照后结构和性能(力学性能、导热性能和热稳定性等)的变化情况。结果表明,两种气氛中,h-BN粉末都具有良好的γ射线辐照稳定性,吸收剂量达到380 kGy时,化学结构和热稳定性均未发生变化。但h-BN/EP复合材料经γ射线辐照后,玻璃化转变温度和初始热分解温度的下降程度都较纯EP基体明显。γ射线辐照对复合材料力学性能的影响与h-BN含量和吸收剂量相关。对于低h-BN含量(质量分数0.52%)的复合材料,其拉伸强度在吸收剂量较低(≤180 k Gy)时即显著下降;而高h-BN含量(质量分数≥0.52%)的复合材料,其拉伸强度在较低剂量(≤180 k Gy)时反而明显上升。当吸收剂量达1 000 kGy时,辐照后不同h-BN含量的复合材料以及纯EP的拉伸强度基本为同一水平,即吸收剂量高于1 000 kGy时,添加h-BN对EP的拉伸强度基本无影响。当吸收剂量为180 kGy时,γ射线辐射使得h-BN/EP复合材料的导热系数显著增加。     

Use of poly(methyl methacrylate) in radioactive waste management: I. Radiation stability and degradation

In this study, in order to understand the possible use of PMMA in radioactive waste management as a solidifying agent, radiation stability of the PMMA was studied by gamma irradiations at two different dose rates of 1485 and 82.8 Gy/h. The total dose of irradiation was up to 523 kGy. Degradation nature was tested by studying the changes in mechanical and thermal properties with rate and total dose of irradiation. Ultimate tensile strength and toughness first increased and then decreased with total irradiation dose. Half value dose (HVD) for elongation was 148 kGy and it was 178 kGy for tensile strength at the dose rate of 1485 Gy/h. Half value dose was found from the extrapolation of experimental data as 228 kGy for elongation and 205 kGy for tensile strength at the dose rate of 82.8 Gy/h. The FTIR spectral analysis showed depolymerization degradation of polymer with irradiation. It was concluded from experimental results that PMMA can be used for embedding radioactive wastes.     

γ-辐照对高密度聚乙烯-尼龙-6共混物结构和性能的影响

用熔融共混的方法制备出高密度聚乙烯(HDPE)和尼龙-6(PA-6)的共混物,研究了共混物经γ射线辐照后结构与性能的改变。扫描电镜(SEM)观察结果表明,γ射线辐照会影响共混物的相态结构;辐照4h后,共混物样品的吸收剂量为15.84kGy;PA-6和HDPE的界面粘结力增强,两相之间有明显的界面过渡层的存在,材料的相容性增加;随着辐照时间延长,材料结构破坏。经γ射线辐照后,共混材料的冲击强度下降,拉伸强度与断裂伸长率增加,其中断裂伸长率增加明显。共混材料经辐照后对二甲苯的吸收减小。     

Characterization of gamma-stabilized PP with blends of hindered amine/phenolic stabilizers

In this work, the effect of γ radiation at doses of 25 and 50 kGy on polypropylene (PP) stabilized with a binary system of antioxidants of the phenol-hindered amine type (BHT-Chimassorb 994) at different compositions (0.1/0.2, 0.1/0.5, 0.1/0.8) was studied. The results showed that the carbonyl index (I_c) of the stabilized samples drastically decreases when compared to that of the pure PP sample. Nonetheless, the I_c values of the different stabilized samples were very similar after irradiation. On the other hand, the average molecular weights (M_w and M_n) and melt flow index (MFI) values decrease in all the samples after irradiation. This effect is less pronounced in PP with 0.1/0.8 of the binary blend of antioxidants. The melting and crystallization peak temperatures and the crystallinity degree remained almost unchanged and the tensile properties such as Young’s modulus and tensile strength did not vary either, except for the elongation at break, which decreases in less proportion in those blends of PP with the antioxidants, independently of the absorbed dose.     

PVA/PEO/Chitosan水凝胶膜的辐照法制备及其性能研究

研究了辐照剂量和壳聚糖含量对水凝胶膜性能的影响。以聚乙烯醇(PVA)、聚氧化乙烯(PEO)和壳聚糖(Chitosan)为原料,采用γ射线辐照法制备了一种新型水凝胶膜。结果表明,随着辐照剂量的增大,凝胶分数会增大,溶胀率会降低;辐照剂量达到21kGy时,凝胶分数可以达到70%,辐照剂量大于21kGy以后,拉伸强度和断裂伸长率会随着辐照剂量的增大而降低;随着壳聚糖含量的增加,水凝胶膜的凝胶分数、拉伸强度和断裂伸长率都会减小,而溶胀率会有一定的提高。辐照后壳聚糖的一些特殊官能团没有改变,将会保持它的抑菌性能,从而获得了一种新型水凝胶膜。     

Oil palm empty fruit bunch (OPEFB) fiber reinforced PVC/ENR blend-electron beam irradiation

The effect of irradiation on the tensile properties of oil palm empty fruit bunch (OPEFB) fiber reinforced poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends were studied. The composites were prepared by mixing the fiber and the PVC/ENR blend using HAAKE Rheomixer at 150 °C. The composites were then irradiated by using a 3.0 MeV electron beam machine at doses ranging from 0 to 100 kGy in air and room temperature. The tensile strength, Young’s modulus, elongation at break and gel fraction of the composites were measured. Comparative studies were also made by using poly(methyl acrylate) grafted OPEFB fiber in the similar blend system. An increase in tensile strength, Young’s modulus and gel fraction, with a concurrent reduction in the elongation at break (Eb) of the PVC/ENR/OPEFB composites were observed upon electron beam irradiation. Studies revealed that grafting of the OPEFB fiber with methyl acrylate did not cause appreciable effect to the tensile properties and gel fraction of the composites upon irradiation. The morphology of fractured surfaces of the composites, examined by a scanning electron microscope showed an improvement in the adhesion between the fiber and the matrix was achieved upon grafting of the fiber with methyl acrylate.     

TAIC对辐照交联无卤阻燃EVA热缩材料的影响

向乙烯-醋酸乙烯共聚物(Ethylene-vinyl acetate copolymer,EVA)无卤阻燃热缩材料中添加不同含量的三烯丙基异氰脲酸酯(Triallyl isocyanurate,TAIC),然后采用电子束辐照,制备出交联型无卤阻燃EVA热缩材料。考察TAIC的含量和吸收剂量对样品的凝胶含量、机械性能和电性能的影响,并通过傅里叶红外(Fourier transform infrared,FTIR)光谱对EVA热缩材料进行表征。结果表明:TAIC的加入对辐射交联有促进作用,在吸收剂量一定的情况下,如150 k Gy,EVA热缩材料的凝胶含量随着TAIC含量增加;在TAIC的添加量一定的情况下,如3份(质量),EVA热缩材料的凝胶含量随着吸收剂量增加;对机械性能而言,断裂伸长率随着TAIC和吸收剂量的增加均呈下降趋势;在断裂强度方面,添加TAIC的样品断裂强度上升趋势比较明显;对电性能的影响,TAIC的加入增加了EVA热缩材料的体积电阻,其随着吸收剂量的增加先上升后下低;FTIR分析表明TAIC在电子束辐照下反应完全。     

Effect of electron beam radiation on the polypropylene/polyethylene blends: Radiation stabilization of polypropylene

The effect of incorporation of polyethylene in the polypropylene matrix, on the radiation sensitivity of polypropylene, has been investigated. The changes in the properties such as tensile strength, elongation at break, Shore D hardness, density and melt flow index were monitored as function of polyethylene content and electron beam radiation dose. A correlation between the mechanical properties and morphology of the irradiated polymeric blends has been observed, which has been explained on the basis of Fourier-transform infrared spectroscopy, scanning electron microscope and X-ray diffraction studies. Improvement in the mechanical properties of the polypropylene, irradiated to an optimum electron beam dose, could be achieved by blending it with polyethylene >20%. The optimum radiation dose was found to be dependent on blend composition and morphology, however, an absorbed dose of 250 kGy found to be effective enough to ensure good mechanical properties of the polypropylene/polyethylene blends.     

辐照交联对膨胀阻燃剂/乙烯-辛烯共聚物复合材料力学性能及阻燃绝缘性能的影响

采用机械共混法向乙烯-辛烯共聚物中添加不同含量的膨胀阻燃剂(聚磷酸铵、季戊四醇、三聚氰胺),然后采用电子束辐照,制备出交联型膨胀阻燃复合材料。通过极限氧指数、热失重、燃烧性能等参数表征电子束辐照交联对其阻燃性能的影响。结果表明,辐照交联后,复合材料的氧指数提高1~2;对力学性能而言,断裂伸长率随着吸收剂量的增加呈现下降趋势,拉伸强度则呈现上升趋势;对热释放的影响,复合材料的燃烧过程缩短,释热、释烟更为集中,在200 kGy吸收剂量下辐射交联后,总热释放量由94.8 MJ/m~2下降至79.1 MJ/m~2,总烟释放量由1 122.9 m~2/m~2下降至928.4 m~2/m~2,燃烧过程缩短约25%,CO释放率由0.062 2kg/kg下降至0.043 9 kg/kg,CO_2生成率由1.44 kg/kg上升至1.51 kg/kg;对绝缘性能而言,随着吸收剂量的增加,材料的体积电阻率变化幅度很小,提示辐照对材料的绝缘性能影响很小。     

Studies on mechanical, thermal and morphological properties of irradiated recycled polyamide and waste rubber powder blends

The aim of this article was to show the effect of gamma irradiation on mechanical and thermal properties of recycled polyamide (rPA) copolymer blended with different content of waste rubber powder (WRP). In order to study the structural modifications of prepared blends have been subjected to irradiation doses up to 200 kGy were applied to all samples. Non-irradiated blends were used as control samples. Mechanical properties, namely, tensile strength (TS), elastic modulus, elongation at break and hardness have been followed up as a function of irradiation dose and degree of loading with rubber content. Furthermore, the influence of radiation dose in the thermal parameters, melting temperature, heat of fusion, ΔH_f of the recycled PA and its blend with waste rubber powder (WRP) was also investigated.     

60Co γ射线辐照剂量对明胶特性和结构的影响

本文以0～60 kGy ⁶⁰Co γ射线辐照的明胶为对象,研究了辐照剂量与明胶的黏度、胶凝特性、力学性能、蛋白组分、分子质量的关系。结果表明：明胶的特性黏度、相对黏度、凝胶强度、断裂伸长率、分子质量与剂量呈良好的负相关;明胶的γ、β、α链含量随剂量的增加而减少,大分子链的降解伴随着小分子多肽链混合物的增加,相对分子质量分布逐渐加宽;明胶膜的断裂强度升高而断裂伸长率下降;辐照后明胶表面结构致密而平滑。在有限水和无限氧气存在条件下,辐照明胶以降解为主,同时伴随着少量的交联,剂量越大,反应程度越高。