Acta Chimica Sinica ›› 2012, Vol. 70 ›› Issue (06): 775-782.DOI: 10.6023/A1110171 Previous Articles     Next Articles

Special Topic

拉伸温度对α'-型聚乳酸结构与性能的影响

陈晓浪a, 徐阳a, 孙志丹b, 张志斌b, 胡书春a, Shaw Ling Hsuc   

  1. a 材料先进技术教育部重点实验室 西南交通大学材料科学与工程学院 成都 610031;
    b 西南交通大学生命科学与工程学院 成都 610031;
    c Polymer Science and Engineering Department and Materials Research Science and Engineering Center, University of Massachusetts, Amherst, Massachusetts 01003, USA
  • 投稿日期:2011-10-17 修回日期:2011-12-12 发布日期:2011-12-22
  • 通讯作者: 陈晓浪
  • 基金资助:

    国家自然科学基金(No. 51003088)、高等学校博士点专项基金(No. 20100184120006)、国家科技支撑计划(No. 2007BAB08B05)、西南交通大学高层次人才项目“竢实之星”(2011)和“希望之星”项目(2008)及中央高校基本科研业务费专项资金(No. SWJTU11ZT10)资助项目.

Effect of Drawing Temperature on Structure and Properties of α'-Phase of Poly(lactic acid)

Chen Xiaolanga, Xu Yanga, Sun Zhidanb, Zhang Zhibinb, Hu Shuchuna, Shaw Ling Hsuc   

  1. a Key Laboratory of Advanced Materials Technology Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031;
    b School of Life Sciences and Engineering, Southwest Jiaotong University, Chengdu 610031;
    c Polymer Science and Engineering Department and Materials Research Science and Engineering Center, University of Massachusetts, Amherst, Massachusetts 01003, USA
  • Received:2011-10-17 Revised:2011-12-12 Published:2011-12-22
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 51003088), Specialized Research Fund for the Doctoral Program of Higher Education (No. 20100184120006), the National Science and Technology Supporting Project Foundation of China (No. 2007BAB08B05), Sishi Star (2011) and Hope Star (2008) Foundations of Southwest Jiaotong University, and the Fundamental Research Funds for the Central Universities (No. SWJTU11ZT10).

Poly(lactic acid) (PLA) films consisting of α'-forms were prepared and uniaxially drawn. The effects of the drawing temperatures above the glass transition temperature on molecular weight and molecular weight distribution, chain conformation, degree of crystallinity and crystalline phase transformation were investigated by a combination of vibrational spectroscopy (infrared and Raman), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The general appearance of stress-strain behaviour of drawn PLA, and in particular its yield stress and Young’s modulus, is strongly affected by the drawing temperatures. The values decrease with increasing the stretching temperatures. The GPC results showed that the molecular weight decreases and its distribution becomes wider after drawing at various drawing temperatures. It was established that the α'-forms phase of PLA films does not transform into either an α or β crystals upon uniaxial drawing with various temperatures at a fixed draw ratio of 4. However, compared with undrawn α'-forms PLA films, the crystallinity and the degree of orientation of PLA products are greatly influenced by the drawing temperatures. The crystallinity is significantly increased upon deformation. The crystallinity and orientation of PLA products increase with increasing the draw temperature when the stretching temperature is <100 ℃, however, the degree of crystallinity and deformation will decrease when the temperature is ≥100 ℃. While the overall changes in physical properties can be attributed to changes in the degree of crystallinity as a function of drawing temperatures, polarized Raman spectra and XRD clearly illustrated changes and the differences in the amorphous and crystalline orientation as a function of processing conditions.

Key words: uniaxially drawn, PLA, crystallization, orientation