LiCl对聚丁内酰胺的热塑改性研究

Study on the Thermoplastic Modification of Polybutyrolactam by LiCl

以LiCl作为增塑剂,采用熔融共混挤出法对聚丁内酰胺(PA4)进行热塑改性制得改性PA4(LiCl/PA4)。利用广角X射线衍射(WAXD)、差示扫描量热(DSC)和拉伸测试等方法对LiCl/PA4的结晶性能、热力学性能和力学性能等进行了研究和分析。结果表明,将LiCl加入到PA4中,由于Li^(+)和C=O中的氧原子发生络合作用,破坏了PA4中分子间的氢键和结晶。随着LiCl含量的增加,LiCl/PA4的熔点和结晶度逐渐减小,断裂伸长率大幅提高,拉伸强度先升高后降低。当LiCl与PA4的质量比为5%时,熔点为223.9℃,结晶度降低至37.88%。当LiCl与PA4的质量比为1%时,拉伸强度最高可增至57.90 MPa。

Polybutyrolactam(PA4)was thermoplastic modified by melt blending extrusion with lithium chloride(LiCl)as the plasticizer.The thermodynamic,crystalline and mechanical properties of LiCl plasticized PA4(LiCl/PA4)were investigated by means of differential scanning calorimetry(DSC),wide-angle X-ray diffraction(WAXD),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FT-IR)and tensile test.XPS results showed that the O atom binding energy of unplasticized PA4 was 531.40 eV.Compared with the unplasticized sample,the binding energy of O atom in LiCl/PA4 system increased by 0.25 eV,while that of N atom was almost unchanged.Therefore,Li+was mainly complexed with oxygen rather than N atomin in amide bond.Such complexation destroyed the intermolecular hydrogen bonds of PA4 and restrained the crystallization.With the increment of LiCl content,the melting point and crystallinity of PA4 gradually decreased.When m(LiCl)∶m(PA4)was 5%,the melting point of LiCl/PA4 decreased to 223.9℃and was 41.6℃lower than that of unplasticized sample.Meanwhile,the crystallinity of plasticized PA4 decreased to 37.88%.In addition,LiCl/PA4 still maintained good mechanical properties.The elongation at break of LiCl/PA4 increased with the addition of LiCl.The maximum elongation at break of LiCl/PA4 was 233%when m(LiCl)∶m(PA4)was 5%,which increased by 155%compared with that of the unplasticized sample.The tensile strength of plasticized PA4 was higher than that of the unplasticized sample,which increased first and then decreased with the increment of LiCl content.The maximum tensile strength reached 57.90 MPa when m(LiCl)∶m(PA4)was 1%.