Question

What are the physicochemical technical parameters of polyethylene glycol PEG-8000?

Answer
2026-06-06 官方文档 聚乙二醇PEG-8000

Polyethylene glycol PEG-8000 is a high molecular weight non-ionic water-soluble polymer whose physicochemical parameters include molecular weight, hydroxyl value, melting point, pH value, and many other key indicators.

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Detailed Description

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Polyethylene glycol PEG-8000 (CAS No.: 25322-68-3) is a high-quality non-ionic surfactant produced by Guoli Chemical. It appears as a white waxy solid or free-flowing powder. Its molecular formula is HO(C2H4O)nH, with a degree of polymerization n of approximately 70~200 and a molecular weight range of 7000~9000. The product has a content of 99% or higher, with excellent solubility, chemical stability, and biocompatibility.

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The HLB value of this product is as high as 19.3, making it a strongly hydrophilic surfactant. It has extremely high solubility in water, forming a clear and transparent solution. Its melting point range is 55~63°C, refractive index is 1.453~1.457 (measured at 70°C), and density is 1.15~1.20 g/cm³ (25°C). The low shear viscosity of a 5% aqueous solution is approximately 5 mPa·s (25°C), with a flash point greater than 240°C. It is a low-foaming product with extremely low foamability.

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In terms of quality indicators, the acid value of PEG-8000 is controlled below 0.5, saponification value is less than 1, moisture content does not exceed 1.0%, free alcohol content does not exceed 0.1%, and heavy metals and arsenic contents are controlled below 10 mg/kg and 2 mg/kg respectively. These strict quality control parameters ensure the product's applicability in high-demand fields such as pharmaceuticals, cosmetics, and biotechnology.

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Technical Parameters

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Parameter CategoryParameter NameSpecification/Value
Basic InformationCAS No.25322-68-3
Molecular FormulaHO(C2H4O)nH, n≈70~200
Physical PropertiesAppearanceWhite waxy solid
Molecular Weight7000~9000
Melting Point55~63°C
Physicochemical IndicatorsHydroxyl Value12~16 mgKOH/g
Acid Value≤0.5 mgKOH/g
Saponification Value<1
Iodine Value<1
UnsaturationSaturated
Solution PropertiespH of 1% Aqueous Solution5.0~7.0
pH of 5% Aqueous Solution4.5~7.5
Viscosity of 5% Aqueous Solution (25°C)Approximately 5 mPa·s
Surface PropertiesHLB Value19.3
Surface Tension63~68 mN/m
Purity IndicatorsActive Content/Solid Content≥99%
Moisture≤1.0%
Free Alcohol≤0.1%
Optical and ThermalRefractive Index (70°C)1.453~1.457
Flash Point>240°C
Other CharacteristicsDensity (25°C)1.15~1.20 g/cm³
Cloud Point>100°C
Safety IndicatorsHeavy Metals≤10 mg/kg
Arsenic≤2 mg/kg
Ion TypeIon TypeNon-ionic
SolubilitySolubilityEasily soluble in water
Foam PerformanceFoam PerformanceLow foaming
HygroscopicityHygroscopicitySlightly hygroscopic
Chemical StabilityChemical StabilityStable, avoid contact with strong oxidizing agents
Alkali ResistanceAlkali ResistanceStable against alkalis
Packaging SpecificationsPackaging200 kg iron drum, 50 kg plastic drum
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Application Suggestions

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Based on the above technical parameters, PEG-8000 has significant advantages in the following scenarios: In the pharmaceutical field, its high purity and low acid value ensure safety as an ointment base and tablet excipient; in biotechnology, the molecular weight range of 7000~9000 is particularly suitable for protein precipitation and crystallization operations; in cosmetic formulations, the HLB value of 19.3 with strong hydrophilicity makes it an ideal O/W emulsion stabilizer; in industrial applications, its excellent lubricity and chemical stability make it suitable for metalworking fluids and rubber mold release agents.

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Precautions

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  • PEG-8000 is slightly hygroscopic. After use, ensure the container is sealed promptly to prevent moisture absorption and caking.
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  • Storage temperature should avoid sustained exposure above 40°C, otherwise it may cause the product to soften and cake.
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  • The surface tension parameter (63~68 mN/m) is relatively high. If a lower system surface tension is required, consider compounding with other low surface tension surfactants.
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  • The product is low-foaming and not suitable for applications requiring high foamability.
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  • The critical micelle concentration (CMC) test result is "none", indicating that the product
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