退火过程中聚己内酯片晶结构的演变

Study on the Evolution of Crystal Structure of Poly(-caprolactone) During Annealing Process

利用一维相关函数研究了退火过程对聚己内酯(PCL)片晶形态与结构的影响。根据广角X射线散射(WAXS)数据计算了PCL的质量结晶度Wc,进而求得其体积结晶度Vc。对小角X射线散射(SAXS)谱线进行一维相关函数分析后得到了PCL的片晶长周期(LP)和无定形层厚度(La),而后求得过渡层厚度(E)。结果表明:PCL在较低温度(30℃)充分等温结晶后,延长等温结晶时间,其相对结晶度基本不变,晶体发生明显的等温增厚现象;晶体在升温过程中,片晶首先发生退火增厚,部分无定形区与过渡区转变为晶区的一部分,晶区厚度(Lc)增大,La与E略有减小;随着温度的进一步提高,较薄的片晶首先熔融,从晶区中溢出后进入无定形区或过渡区,故Lc随之降低,La与E逐渐增大;最后所有片晶全部转变为无定形状态。

The effect of thermal annealing process on the lamellar morphology of poly（-caprolactone） was investigated by using simultaneous measurement of wide-angle/small-angle X-ray scattering（SAXS/WAXS） and one-dimensional correlation function（1DCF） analysis.On the basis of the weight fraction of crystallinity obtained from WAXS result,the volume fraction crystallinity（Vc（WAXS）） of PCL was calculated.The long period（LP） and thickness of the amorphous region（La） were obtained through the 1DCF analysis of SAXS profiles,and then the lamellar thickness of the transition zone between the crystalline and amorphous region（E） was deduced.The results show that： during the isothermal process of 30 ℃,the relative crystallinity of PCL is invariant basicly and the lamellar thickens.Alternatively,during the beginning of heating annealing process,PCL lamellar thickens with increase of the heating temperature,and La and E decrease slightly.And then the thinner PCL melts firstly and then overflows into amorphous region or transition region.Finally,the lamellar turns completely into amorphous state.