When mixing recycled PES (re-pelletized or regrind) with virgin pellets, it is necessary to adjust the mixing ratio according to the grade and application. Table 4-4-1 shows the recommended mixing ratios of recycled PES for each grade.

Table 4-4-1 Recommended Mixing Ratios of Recycled PES

Grade	Ratio of recycled PES (%)
4100G / 4800G	30 or less
3601GL20 / 4101GL20	20 or less
3601GL30 / 4101GL30	10 or less

Non-reinforced grades may darken the color of the molded products and become brittle if too much recycled PES are used. For glass fiber reinforced grades, the amount of recycled PES that can be added is limited to smaller quantities because the glass fibers shorten during re-pelletizing or regrinding, which result in a loss of mechanical strength. Table 4-4-2 shows the impacts on mechanical properties when recycled PES is used for SUMIKAEXCEL PES.

Table 4-4-2 Impacts of Using Recycled PES against SUMIKAEXCEL PES on Tensile Properties

Grade		4100G / 4800G				3601GL20 / 4101GL20
Ratio of recycled PES (%)		30		100		30	100
Property		Tensile strength (MPa)	Mode of break	Tensile strength (MPa)	Mode of break	Tensile strength (MPa)	Tensile strength (MPa)
Number of recycling times	Virgin	86	Ductile	86	Ductile	126	126
	1	87	Ductile	87	Ductile	126	121
	2	89	Ductile	87	Ductile	125	116
	3	88	Ductile	87	Ductile	126	109
	4	88	Ductile	88	Ductile	124	102
	5	89	Ductile	87	Ductile	122	98