Thermal， mechanical and barrier properties of PLLA/PDBI blend films

doi:10.19491/j.issn.1001-9278.2024.12.010

Abstract

Abstract:

Poly（lactic acid⁃co⁃glycolic acid butylenediyl ester）（PDBI） was synthesized by incorporating poly（butylene glycol itaconate）（PBI） into the main chains of poly（D⁃lactic acid）（PDLA）， and then the PLLA/PDBI blend films were prepared by melt blending the as⁃synthesized PDBI with poly （L⁃lactic acid）（PLLA） at different mass ratios. The results indicated that the total crystallinity degree of the blend films presented an increasing trend at first and then decreased with an increase in the mass ratio of PDBI to PLLA， and the most cubic composite crystals were formed at a PDBI/PLLA mass ratio of 1/1. At such a mass ratio， the blend films obtained a total crystallinity degree of 9.12 % with a melting point as high as 205 ℃， and their thermal properties were greatly improved. The elongation at break of the blend films exhibited an increasing trend at first and then decreased with an increase in the mass ratio of PDBI to PLLA， whereas their tensile strength and Young's modulus presented an opposite trend. The PDBI/PLLA blend film at a mass ratio of 1/1 presented a Young's modulus of 853.38 MPa and elongation at break of 285.07 %. There was no change in the tensile strength； however， its elongation at break was 59 times as much as that of PLLA and 21 times as much as that of PDBI， indicating a change from a brittle fracture to the ductile one. The barrier performance of the blend films also showed an enhancement at first and then became weakened. At a PDBI/PLLA mass ratio of 1/1， the blend film exhibited an O₂ transmission amount of 309.4 cm³·m²/d and a maximum water contact angle of over 78 °， indicating good barrier performance and high hydrophobicity.

Key words: poly（lactic acid）, poly（butylene glycol） itaconic acid, thermal performance, mechanical performance, barrier performance

CLC Number:

TQ321

REN Siying, DU Jiahui, SUN Tao, WU Yifeng, GUO Jiushi, YUN Xueyan. Thermal， mechanical and barrier properties of PLLA/PDBI blend films[J]. China Plastics, 2024, 38(12): 60-65.

Figures/Tables 10

References 21

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样品	M_n/kg·mol^-1	M_w/kg·mol^-1	PDI
PBI	0.23	0.36	1.6
ODLA	0.28	0.38	1.7
OLLA	0.27	0.43	1.5
PLLA	3.8	7.2	1.6
PDBI	3.1	6.6	1.7

样品	M_n/kg·mol^-1	M_w/kg·mol^-1	PDI
PBI	0.23	0.36	1.6
ODLA	0.28	0.38	1.7
OLLA	0.27	0.43	1.5
PLLA	3.8	7.2	1.6
PDBI	3.1	6.6	1.7

样品	T_g/℃	T_c/℃	∆H_c/J·g^-1	T_m1/℃	∆H_m1/J·g^-1	T_m2/℃	∆H_m2/J·g^-1	X_HC/%	X_SC/%	X_total/ %
PLLA	45.78	94.06	19.89	162.35	22.13	-	-	2.41	0	2.41
PLLA/PDBI25	51.38	110.69	10.96	159.95	11.49	191.95	14.58	0.82	2.92	3.74
PLLA/PDBI50	53.59	97.46	12.75	158.29	12.76	205.97	23.85	0.60	8.52	9.12
PLLA/PDBI75	46.45	101.68	6.497	135.87	9.024	193.27	8.740	2.59	1.97	4.56
PDBI	31.55	84.64	18.74	136.39	21.31	-	-	2.76	0	2.76

样品	T_g/℃	T_c/℃	∆H_c/J·g^-1	T_m1/℃	∆H_m1/J·g^-1	T_m2/℃	∆H_m2/J·g^-1	X_HC/%	X_SC/%	X_total/ %
PLLA	45.78	94.06	19.89	162.35	22.13	-	-	2.41	0	2.41
PLLA/PDBI25	51.38	110.69	10.96	159.95	11.49	191.95	14.58	0.82	2.92	3.74
PLLA/PDBI50	53.59	97.46	12.75	158.29	12.76	205.97	23.85	0.60	8.52	9.12
PLLA/PDBI75	46.45	101.68	6.497	135.87	9.024	193.27	8.740	2.59	1.97	4.56
PDBI	31.55	84.64	18.74	136.39	21.31	-	-	2.76	0	2.76

样品	拉伸强度/MPa	断裂伸长率/ %	弹性模量/ MPa
PLLA	39.84±3.18	4.83±0.12	1 587.48±79.37
PLLA/25 %PDBI	35.49±1.07	8.47±3.13	1 258.76±54.13
PLLA/50 %PDBI	29.76±0.75	285.07±13.58	853.38±34.99
PLLA/75 %PDBI	29.93±1.15	3.07±0.58	927.64±47.31
PDBI	19.28±0.98	13.23±1.16	563.44±29.86