Effect of surface treatment of ramie fiber on crystallization behavior and tensile properties of poly（lactic acid）

doi:10.19491/j.issn.1001-9278.2022.11.008

Abstract

Abstract:

The effect of surface treatment parameters of ramie fibers （RF） on the crystallization behavior and tensile proper⁃ties of molded polylactic acid （PLA）/RF composites were investigated using polarized light microscopy， differential scanning calorimetry， and scanning electron microscopy. The results indicated that the crystallization behavior of PLA was greatly affected by the alkaline treatment time of RF surface. After the RF surface was treated for 3 h， PLA presented an increase in transcrystalline density. Its cold⁃crystallization temperature was reduced， but its relative degree of crystallinity was improved. When the treatment time was increased to 6 h， the crystallization of PLA was hindered by RF. The Mo’s method was adopted to study the non⁃isothermal crystallization kinetics of PLA quantitatively. The results indicated that the change of the fiber morphology did not cause a change in the crystallization mechanism of PLA. The tensile test results showed that the optimal strengthening and toughening effects were achieved for the PLA/RF composites at an alkaline treatment time of 6 h. In this case， the composites exhibited an increase in tensile strength and elongation by 19.6 % and 23.9 %， respectively.

Key words: poly（lactic acid）, ramie fiber, alkaline treatment, crystallization behavior, tensile property

CLC Number:

TQ321

LI Guili, YU Qiuran, HAO Mingliang, LI Haimei. Effect of surface treatment of ramie fiber on crystallization behavior and tensile properties of poly（lactic acid）[J]. China Plastics, 2022, 36(11): 51-58.

Figures/Tables 12

References 24

1	Liu J L， Yang Y F， Ding J N. The value of China’s legislation on plastic pollution prevention in 2020［J］. Bulletin of Environmental Contamination and Toxicology， 2021， 108（4）：601⁃608.
2	Chae Y， An Y J. Current research trends on plastic pollution and ecological impacts on the soil ecosystem： A review［J］. Environmental Pollution， 2018， 240：387⁃395.
3	李岩，李倩. 植物纤维增强复合材料力学高性能化与多功能化研究［J］. 固体力学学报， 2017， 38（3）：215⁃243.
	LI Y， LI Q. High mechanical perormance and multi⁃functionlities of plant fiber reinforced composites［J］. Chinese Journal of solid mechanics， 2017， 38（3）：215⁃243.
4	Siakeng R， Jawaid M， Ariffin H， et al. Mechanical， dynamic， and thermomechanical properties of coir/pineapple leaf fiber reinforced polylactic acid hybrid biocomposites［J］. Polymer Composites， 2019， 40（5）：2 000⁃2 011.
5	Wang H， Memon H， Hassan Elwathig A M， et al. Rheological and dynamic mechanical properties of abutilon natural straw and polylactic acid biocomposites［J］. International Journal of Polymer Science， 2019：8732520.
6	Rajeshkumar G， Seshadri S A， Devnani G L， et al. Environment friendly， renewable and sustainable poly lactic acid （PLA） based natural fiber reinforced composites⁃A comprehensive review［J］. Journal of Cleaner Production， 2021， 310： 127483.
7	文泽伟，刘福亚，崔晓杰，等. 机械力改性芦苇纤维及其对聚乳酸复合材料的阻燃性能研究［J］. 中国塑料， 2021， 35（11）：38⁃43.
	WEN Z W， LIU F Y， CUI X J， et al. Mechanical modification of polylactic acid with reed fibers for flame⁃retardant application［J］. China Plastics， 2021， 35（11）：38⁃43.
8	夏学莲，史向阳，赵海鹏，等. γ射线辐照对PLA/Flax复合材料结晶行为的影响［J］. 包装工程， 2020， 41（13）： 154⁃160.
	XIA X L， SHI X Y， ZHAO H P， et al. Effect of γ⁃ray irradiation on crystallization behavior of PLA/flax composites［J］. Packing Engineering， 2020， 41（13）： 154⁃160.
9	Li G L， Hao M L， Chen Y F， et al. Nonisothermal crystallization behavior and mechanical properties of poly（lactic acid）/ramie fiber biocomposites［J］. Polymer Composites， 2022， 43（5）：2 759⁃2 770.
10	Sawpan M A， Pickering K L， Fernyhough A. Improvement of mechanical performance of industrial hemp fibre reinforced polylactide biocomposites［J］. Composites Part A： Applied Science and Manufacturing， 2011， 42（3）： 310⁃319.
11	Orue A， Eceiza A， Arbelaiz A. The effect of sisal fiber surface treatments， plasticizer addition and annealing process on the crystallization and the thermo⁃mechanical proper⁃ties of poly（lactic acid） composites［J］. Industrial Crops and Products， 2018， 118：321⁃333.
12	Li G L， Yang B L， Han W J， et al. Tailoring the thermal and mechanical properties of injection⁃molded poly（lactic acid） parts through annealing［J］. Journal Applied Polymer Science， 2021， 138（2）：49648.
13	Wang G L， Zhang D M， Li B， et al. Strong and thermal⁃resistance glass fiber⁃reinforced polylactic acid （PLA） composites enabled by heat treatment［J］. International Journal of Biological Macromolecules， 2019， 129： 448⁃459.
14	Deng L， Xu C， Wang X H， et al. Supertoughened polylactide binary blend with high heat deflection temperature achieved by thermal annealing above the glass transition temperature［J］. ACS Sustainable Chemistry & Enginee⁃ring， 2017， 6（1）： 480⁃490.
15	Nagarajan V， Zhang K， Misra M， et al. Overcoming the fundamental challenges in improving the impact strength and crystallinity of PLA biocomposites： influence of nuclea⁃ting agent and mold temperature［J］. ACS Applied Materials & Interfaces， 2015， 7（21）： 112 003⁃112 014.
16	Mazzanti V， De Luna M S， Pariante R， et al. Natural fiber⁃induced degradation in PLA⁃hemp biocomposites in the molten state［J］. Composites Part A： Applied Science and Manufacturing， 2020， 137：105990.
17	Qian S P， Mao H L， Sheng K C， et al. Effect of low⁃concentration alkali solution pretreatment on the properties of bamboo particles reinforced poly（lactic acid） composites［J］. Journal of Applied Polymer Science， 2013， 3：1 667⁃1 674.
18	Fischer E W， Sterzel H J， Wegner G. Investigation of the structure of solution grown crystals of lactide copolymers by means of chemical reactions［J］. Steinkopff， 1973， 251（11）：980⁃990.
19	Li G L， Hou X Q， Li H M， et al. Interfacial cylindrite of poly（lactic acid） induced by pulling a single glass fiber［J］. European Polymer Journal， 2019， 114：127⁃133.
20	Cebe P， Hong S D. Crystallization behavior of poly（etheretherketone）［J］. Polymer， 1986， 27（8）：1 183⁃1 192.
21	张静，王洪，邹威，等. 改性纤维素纳米晶对聚酰胺6结晶行为的影响［J］. 中国塑料， 2020， 43（6）：1⁃6.
	ZHANG J， WANG H， ZOU W， et al. Effect of modified cellulose nanocrystals on crystallization behavior of polyamide 6［J］. China Plastics， 2020，43（6）：1⁃6.
22	Avrami M. Kinetics of phase change. ii transformation⁃time relations for random distribution of nuclei［J］. Journal of Chemical Physics， 1940， 8（2）： 212⁃224.
23	Senthamaraikannan P， Saravanakumar S S， Sanjay M R， et al. Physico⁃chemical and thermal properties of untreated and treated Acacia planifrons bark fibers for composite reinforcement［J］. Materials Letters， 2019， 240： 221⁃224.
24	丰波，谢俊康，李富强，等. PE⁃LD/桉木粉复合材料的制备及其性能研究［J］. 中国塑料， 2018， 32（9）：42⁃48.
	FENG B， XIE J K， LI F Q， et l. Preparation and properties of wood plastic composites based on PE⁃LD and eucalyptus flour powders［J］. China Plastics， 2018，32（9）：42⁃48.

样品	T_g/℃	T_c1/℃	T_c2/℃	T_m/℃	ΔH_c/J·g^-1	ΔH_m/J·g^-1	X_c/%
PLA/RF⁃0	59.8	101.0	153.7	167.0	17.5	30.9	16.8
PLA/RF⁃3	60.1	100.3	154.0	167.2	26.6	34.5	9.9
PLA/RF⁃6	60.4	105.2	153.3	166.9	24.5	60.3	7.7
PLA/RF⁃9	60.0	101.2	154.7	166.6	30.8	34.5	4.6
PLA/RF⁃0^#	60.4	101.8	153.9	166.8	11.4	31.1	24.7
PLA/RF⁃3^#	60.3	100.3	153.4	166.6	9.2	34.3	31.5
PLA/RF⁃6^#	60.5	106.1	153.6	166.8	13.7	30.3	20.8
PLA/RF⁃9^#	58.7	102.9	154.2	166.2	13.3	35.2	27.6

样品	T_g/℃	T_c1/℃	T_c2/℃	T_m/℃	ΔH_c/J·g^-1	ΔH_m/J·g^-1	X_c/%
PLA/RF⁃0	59.8	101.0	153.7	167.0	17.5	30.9	16.8
PLA/RF⁃3	60.1	100.3	154.0	167.2	26.6	34.5	9.9
PLA/RF⁃6	60.4	105.2	153.3	166.9	24.5	60.3	7.7
PLA/RF⁃9	60.0	101.2	154.7	166.6	30.8	34.5	4.6
PLA/RF⁃0^#	60.4	101.8	153.9	166.8	11.4	31.1	24.7
PLA/RF⁃3^#	60.3	100.3	153.4	166.6	9.2	34.3	31.5
PLA/RF⁃6^#	60.5	106.1	153.6	166.8	13.7	30.3	20.8
PLA/RF⁃9^#	58.7	102.9	154.2	166.2	13.3	35.2	27.6

样品	Φ/℃·min^-1	T_p/℃	∆ω/℃	t_1/2/min
PLA/RF⁃0	10.0	97.3	54.7	3.1
	5.0	112.0	51.8	4.6
	2.5	121.5	29.9	6.6
	1.0	130.8	15.6	9.5
PLA/RF⁃3	10.0	100.1	52.7	2.9
	5.0	113.2	51.5	4.3
	2.5	122.2	27.8	6.4
	1.0	131.4	14.8	9.0
PLA/RF⁃6	10.0	96.7	55.4	3.3
	5.0	109.1	54.8	4.9
	2.5	120.2	31.0	7.2
	1.0	128.6	16.8	11.0

样品	Φ/℃·min^-1	T_p/℃	∆ω/℃	t_1/2/min
PLA/RF⁃0	10.0	97.3	54.7	3.1
	5.0	112.0	51.8	4.6
	2.5	121.5	29.9	6.6
	1.0	130.8	15.6	9.5
PLA/RF⁃3	10.0	100.1	52.7	2.9
	5.0	113.2	51.5	4.3
	2.5	122.2	27.8	6.4
	1.0	131.4	14.8	9.0
PLA/RF⁃6	10.0	96.7	55.4	3.3
	5.0	109.1	54.8	4.9
	2.5	120.2	31.0	7.2
	1.0	128.6	16.8	11.0

样品	X_c （t）/%	F（T）/K∙min ^a^-1	a
PLA/RF⁃0	20	43.55	1.85
	40	80.64	1.96
	60	134.29	2.05
	80	214.22	2.11
PLA/RF⁃3	20	41.35	1.92
	40	73.26	2.01
	60	115.35	2.05
	80	185.86	2.07
PLA/RF⁃6	20	44.79	1.77
	40	83.60	1.88
	60	140.19	1.99
	80	222.30	2.08