Structure and properties of high⁃adhesion thermoplastic starch⁃based hot melt adhesive with controllable viscoelasticity

doi:10.19491/j.issn.1001-9278.2025.07.007

Abstract

Abstract:

A high⁃adhesion thermoplastic starch⁃based hot melt adhesive （HMA） was prepared using a two⁃step method involving tartaric acid⁃modified thermoplastic starch （TPSTA1）. Ethylene⁃vinyl acetate （EVA）， rosin， and aluminum powders were incorporated into HMA via melt blending. The effects of varying EVA， rosin， and aluminum powder content on the adhesive's flow properties， adhesion strength， viscoelasticity， and compatibility were systematically investigated. Experimental results indicated that increasing the HMA （a blend of EVA and rosin） and aluminum powder contents initially enhanced adhesive strength， flowability， and surface energy， followed by a subsequent decrease. Optimized formulations significantly improved adhesive strength in copper lap joints， aluminum foil peel tests， and nonwoven fabric peel tests. Furthermore， incorporating HMA and aluminum powders disrupted the hydrogen bonding network within TPSTA1， enhancing starch chain molecular mobility. This caused a shift from predominantly viscoelastic to more viscous behavior， thereby improving the adhesive system's stability. Microstructural analysis indicated limited compatibility between TPSTA1 and rosin at high HMA contents， resulting in a sea⁃island morphology. EVA acted as a compatibility enhancer， improving interfacial adhesion. Aluminum powders dispersed uniformly at low concentrations but exhibited agglomeration tendencies at higher levels. This study provides theoretical support for optimizing the performance and expanding the application potential of thermoplastic starch⁃based hot melt adhesives.

Key words: hot melt adhesive, thermoplastic starch, biobased, high bonding strength, interfacial adhesion

CLC Number:

TQ321.2

LI Manlin, YAN Yu, GAO Bingbing, HU Zanjun, ZHANG Shuidong. Structure and properties of high⁃adhesion thermoplastic starch⁃based hot melt adhesive with controllable viscoelasticity[J]. China Plastics, 2025, 39(7): 32-43.

Figures/Tables 23

Fig.1. Adhesion strength of hot melt adhesives with different TA content

Fig.2. Adhesion strength of samples with different HMA ratios and different aluminum powder content

样品	破坏形式	剥离强度/N·m^-1
TPATA1	内聚破坏	387.6
90TPATA1/10HMA	破材	—
80TPATA1/20HMA	破材	—
70TPATA1/30HMA	破材	—
60TPATA1/40HMA	混合破坏	710.0
50TPATA1/50HMA	混合破坏	546.7
HMA	混合破坏	460.0

Tab.1. Test results of T⁃shaped peel adhesion of non⁃woven fabrics （different HMA ratios）

样品	破坏形式	剥离强度/N·m^-1
80TPATA1/20HMA	破材	—
80TPATA1/20HMA/1Al	混合破坏	415.0
80TPATA1/20HMA/3Al	混合破坏	256.7
80TPATA1/20HMA/5Al	界面破坏	250.0
80TPATA1/20HMA/7Al	界面破坏	100.0

Tab.2. Test results of T⁃shaped peel adhesion of non⁃woven fabrics （different aluminum powder content）

Fig.3. Melt index of samples with different HMA ratios and different aluminum powder content

Fig.4. Complex viscosity of samples with different HMA ratios and different aluminum powder content

Fig.5. Water contact angle and surface energy of samples with different HMA ratios and different aluminum powder content

Fig.6. Micromorphology of the bonding failure interface of copper sheet

Fig.7. Micromorphology of the peeling adhesion failure interface of non⁃woven fabrics

Fig.8. Micromorphology of the peeling adhesive failure interface of non⁃woven fabrics

Fig.9. Micromorphology of the cross⁃section of the nonwoven fabric peeling adhesive spline

Fig.10. Tensile curves of samples with different HMA ratios and different aluminum powder content

Fig.11. Stress relaxation curves of samples with different HMA ratios and different aluminum powder content

样品	松弛时间/τ/s
TPSTA1	126.1
90TPSTA1/10HMA	110.5
80TPSTA1/20HMA	52.5
70TPSTA1/30HMA	—
60TPSTA1/40HMA	—
50TPSTA1/50HMA	—
HMA	—
80TPSTA1/20HMA	52.5
80TPSTA1/20HMA/1Al	50.6
80TPSTA1/20HMA/3Al	28.1
80TPSTA1/20HMA/5Al	69.9
80TPSTA1/20HMA/7Al	85.5

Tab.3. Relaxation time of samples

Fig.12. Dynamic rheological stress scanning curve

样品	临界应变γ_c
TPSTA1	7.8 %
90TPSTA1/10HMA	3.5 %
80TPSTA1/20HMA	2.2 %
70TPSTA1/30HMA	2.4 %
60TPSTA1/40HMA	2.7 %
50TPSTA1/50HMA	2.9 %
HMA	8.5 %

Tab.4. Critical strain of samples with different HMA ratios

样品	临界应变γ_c
80TPSTA1/20HMA	2.2 %
80TPSTA1/20HMA/1Al	1.0 %
80TPSTA1/20HMA/3Al	1.0 %
80TPSTA1/20HMA/5Al	1.2 %
80TPSTA1/20HMA/7Al	1.6 %

Tab.5. Critical strain of samples with different aluminum powder content

Fig.13. Dynamic rheological stress scanning curve

Fig.14. Statistical diagram of cyclic stretching and hysteresis recovery rate

Fig.15. DMA curves of the samples

Fig.16. Micromorphology of sample frozen brittle section

Fig.17. Micromorphology of sample frozen brittle section

Fig.18. Dispersion of aluminum powder in colloid

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