Structure and property evolutions of rPE⁃HD/rPET blending system via volume⁃pulsatile injection molding

doi:10.19491/j.issn.1001-9278.2024.08.001

Abstract

Abstract:

In this study， high⁃density polyethylene （PE⁃HD） and polyethylene terephthalate （PET） as two common components of plastic wastes were employed as experimental materials. The mass ratios of PE⁃HD to PET were set to be 9/1， 8/2 and 7/3. A screw extruder was used to repeat the melt regeneration， and the volume⁃pulsatile injection molding method was used to prepare the reinforced/toughened hybrid recycled materials. The mechanical properties of the multi⁃recycled materials were significantly improved. The influence of injection molding method on the microstructure of the injection⁃molded samples was analyzed. The results indicated that the pulsatile stress field introduced by volume⁃pulsatile injection molding could improve the compatibility of the incompatible two phases effectively and induce the formation of in⁃situ submicron⁃fibril of the minor phase and the change of crystal morphology. This contributes to the formation of interlinked hybrid shish⁃kebab structure. Mechanical test results indicated that when the PE⁃HD/PET mass ratio was set to be 9/1， the hybrid recycled material prepared by volume⁃pulsatile injection molding exhibited yield strength and impact toughness of 38.7 MPa and 165 kJ/m²， which were 54.8 % and 3 675.7 % higher than those of conventional injection molded material. When the PE⁃HD/PET mass ratio was 7/3， the yield strength and impact toughness of the hybrid recycled material were 31.0 MPa and 11.6 kJ/m²， respectively， increased by 14.8 % and 216.1 % compared to those of conventional injection⁃molded material.

Key words: volume?pulsatile injection molding, physical recycling, high?density polyethylene, reinforcement and toughening, pulsatile stress field

CLC Number:

TQ320.6

LIANG Jifeng, QU Jinping. Structure and property evolutions of rPE⁃HD/rPET blending system via volume⁃pulsatile injection molding[J]. China Plastics, 2024, 38(8): 1-7.

Figures/Tables 10

材料	不同加热段的温度设定/℃									螺杆转速/r·min^-1
材料	1	2	3	4	5	6	7	8	9	螺杆转速/r·min^-1
PE⁃HD	140	160	190	200	210	220	220	220	200	200
PET	240	250	260	260	265	265	265	255	245	150
PE⁃HD/PET	230	250	260	260	265	265	265	255	245	150

Tab.1. Parameters of the extrusion process

Fig.1. Mechanical properties of the samples

Fig.2. Micromorphology of the rPE⁃HD/rPET mixed recycled samples

Fig.3. Crystal morphologies of the rPE⁃HD/rPET mixed recycled samples

Fig.4. Impact⁃fractured cracks of the rPE⁃HD/rPET mixed recycled samples

Fig.5. Impact⁃fractured morphologies of the rPE⁃HD/rPET mixed recycled samples

Fig.6. DSC curves of the rPE⁃HD/rPET mixed recycled samples

样品	熔点/℃	结晶度/%
V91	126.7	60.52
V82	124.9	59.22
V73	123.6	60.02
C91	124.3	59.76
C82	123.0	58.19
C73	123.2	56.12

Tab.2. Melting points and crystallinities of the samples

Fig.7. 2D⁃WAXD results of the rPE⁃HD/rPET mixed recycled samples

Fig.8. 2D⁃SAXS results of the rPE⁃HD/rPET mixed recycled samples

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