尼龙餐厨具在热氧条件下的老化行为研究

Study on aging behavior of nylon tableware under hot-oxygen condition

目的对尼龙餐厨具样品进行差示扫描量热(differential scanning calorimetry,DSC)原位热氧加速老化行为研究,分析老化温度和老化时间对样品熔点和热稳定性能的影响。方法采用傅立叶变换红外光谱法(Fourier transform infrared spectroscopy,FTIR)探究老化温度和老化时间与样品分子结构变化之间的关系。结果在模拟使用温度100~260℃范围内,随着DSC热氧老化温度的上升,样品的短期老化作用不明显。在模拟极限使用温度240℃条件下,样品的老化以氧化作用为主,且随热氧老化时间的延长,样品分子链的支化和断链程度加剧,同时伴随着交联现象,总体氧化稳定性变差。结论在极限使用温度240℃条件下,当热氧老化时间短于30min时,市售尼龙餐厨具具有良好的耐热氧稳定性,但若热氧老化时间在延长至60min以上时,其内在结构可能因热氧老化作用发生变化且产生酮等氧化产物,存在安全风险。

Objective To study the accelerated aging behavior of nylon tablewares by differential scanning calorimetry(DSC)in situ hot-oxygen and analyze the effects of aging temperature and aging time on the melting point and thermal stability of samples.Methods The relationship between aging temperature and aging time and molecular structure changes of samples was investigated by Fourier transform infrared spectroscopy(FTIR).Results The short-term aging effect of the sample was not obvious with the increase of DSC thermal oxygen aging temperature in the range of simulated use temperature of 100-260℃.Under the condition of the extreme use temperature of 240℃,the aging effect of the sample was dominated by oxidation,and with the prolongation of the hot-oxygen aging time,the branching and chain scission degrees of the sample molecular chain were intensified.The overall oxidation stability got worse,with the cross-linking phenomenon.Conclusion When the thermal oxygen aging time is less than 30 min,the commercial nylon tablewares have good heat-resistant and oxygen stability under the condition of the extreme service temperature of 240℃.However,if the thermal oxygen aging time is extended to more than 60 min,its internal structure may change due to thermal oxygen aging and produce ketone and other oxidation products,which has a safety risk.