PVC-U型材国家标准中耐候性检测方法的探讨

Discussion on the weather resistance testing method in national standard of PVC-U tubes

按照GB/T 8814—2004《门、窗用未增塑聚氯乙烯(PVC-U)型材》进行了4 000h老化试验,考察了样品ΔE*、Δb*和光泽度的变化。结果表明:①所有样品在2 000h时都出现了变色峰值,而且峰值都超过GB/T8814—2004的规定,但到4 000h时样品的变色情况反而达标;②PVC型材表面颜色的变化不仅是PVC老化的结果,同时也是其表面粉化的结果;③GB/T 8814—2004对PVC型材耐候性的检测方法存在不足,应适当地对样品的老化过程进行跟踪和评估。

Ageing test of 4 000 h are carried out according to GB/T 8814- 2004 Unplasticized Pol yvinyl Chloride （ PVC-U） Profiles for the Fabrication of Doors and Windows to investigate samples＇ changes in △E＊ , △b＊ and glossiness. The results show that （1） discoloration of all the samples appears peak value at 2 000 h and all the peak value exceed the specified value in GB/T 8814 - 2004, but the discoloration of all the samples at 4 000 h reaches to the standard; （2） not only PVC＇s ageing but also its surface chalking contributes to change in surface color of PVC profiles; （3） there are shortcomings in the test method of weather resistance of PVC profiles in GB/T 8814 - 2004, and thus the samples＇ ageing process should be tracked and evaluated appropriately.