【作者】 吕晓雷；

【导师】 陈明清；

【作者基本信息】 江南大学 ， 材料学， 2009， 硕士

【摘要】 目前国内桥梁缆索护套一般采用高密度聚乙烯(HDPE),但其在自然条件下达不到长期使用的目的,为制备出耐候性好的护套材料,本文从以下几个方面进行了研究。超高分子量聚乙烯(UHMWPE)具有优良的耐候性,耐紫外光性能,本文采用UHMWPE与HDPE共混改性,以提高护套料的抗紫外线性能。因为考察护套料的老化试验时间长,自制了310nm的高功率(3KW)高辐照强度(89w/m~2)紫外老化箱,对共混改性样品进行加速老化试验,与自然条件下间接换算,人工加速老化大约大于300h相当于自然条件下100年。发现在UHMWPE与HDPE配比为1:1时,与纯的HDPE相比,在紫外光照射7h时其断裂伸长保留率依然保持在80%,优于日本树脂,但加工性能相对较差;当UHMWPE与双峰聚乙烯(BPE)的配比为3:7时,抗紫外线性能稍低于UHMWPE与HDPE配比为1:1的样品,但与纯的BPE相比,抗紫外线性能得到提高,而加工性能好于UHMWPE与HDPE配比为1:1的样品。通过傅里叶变换红外(FTIR)和扫描电子显微镜(SEM)对不同辐照时间的样品分析可知:老化层出现了C=0的特征吸收,表面出现了裂纹,这是由于聚乙烯主链发生断裂并被部分氧化所引起的。通过对不同辐照时间样品的结晶度分析,发现无规律性变化,这可能是在高强度紫外光辐照下,样品出现了复杂的物理-化学变化。为了进一步提高改性样品的抗老化性能,在确定基料配方的基础上,固定抗氧剂,抗紫外线剂用量,探讨了炭黑种类及用量对提高抗紫外线性能的影响,发现炭黑含量在2.5phr,助剂含量不超过于0.5phr时抗紫外线性能最佳。通过对比试验可知,无论是基料还是黑色护套料,其抗紫外线性能明显好于日本树脂与日本黑色护套料。因此用UHMWPE进行改性能明显提高样品的抗紫外线性能,达到了桥梁护套的要求。更多还原

【Abstract】 At present, high-density polyethylene (HDPE) is used generally the bridge jacket, but its durability is not long .So the following aspects have been studied in the this article.UHMWPE with excellent weatherability and UV-resistance was employed to improve the anti-ultraviolet property of HDPE. As the long time of aging test under natural conditions, a self-made UV aging chamber of 310nm in wave length, high-power (3KW), high radialization and irradiation intensity (89w/m~2) was used to accelerate the aging test. Artificial accelerated aging of 300h approximately equivalents to more than 100 years under natural conditions. The results showed that the elongation at break of UHMWPE and HDPE blend (weight ratio: UHMWPE: HDPE=1:1) still remained 80% compared with that of pristine HDPE after UV irradiated for 7h, which excelled the Japanese resin, but its processing performance is poor. Although the UV-resistance of UHMWPE and Bimodal polyethylene (BPE) blend (weight ratio: UHMWPE: BPE =3:7) was slightly poorer than that of UHMWPE and HDPE blend (weight ratio: UHMWPE: HDPE=1:1), its UV-resistance was improved compared with the pristine BPE.Samples of different irradiation time were analyzed by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM), the results suggested that the characteristic absorption peek of C=O in aging layer and the cracks in the surface were caused by the break and partial oxidation of polyethylene main chains. Crystallinity analysis showed random changes, which may due to the complicated physical - chemical reactions under high-intensity UV irradiation.To improve the anti-aging properties of the modified samples further, the influences of different carbon blacks and their amounts on UV-resistance were investigated based on the previous matrix material with fixed amounts antioxidant and anti-UV dosage. The results showed that the material with carbon black content of 2.5phr and additive content of no more than 0.5phr had the best UV-resistance.By comparing the tests, it is found that the UV-resistances of both the matrix and black jacket material were prior to Japanese resin and Japanese black jacket material. Therefore, UHMWPE markedly improves the UV-resistance of HDPE, which could meet the requirements of the bridge sheath.更多还原