HIPS Lianyungang Petrochemical STL88

Material Introduction: HIPS Lianyungang Petrochemical STL88 is a high‑impact polystyrene. It features high impact resistance, good toughness, easy processability and strong tinting strength, while its flowability is slightly inferior to general‑purpose polystyrene.

Main Applications

Electrical appliance housings (televisions, commercial machines), instruments and meters, household appliances, toys, packaging materials, etc.

Physical Properties

Performance Category	Test Item	Reference Test Standard	Unit	Typical Value / Range (General PS)	Typical Value / Range (General HIPS)
Physical Properties	Density	ASTM D792	g/cm³	1.04‑1.09	1.035‑1.04
	Melt Flow Rate (MFR)	ASTM D1238	g/10min	‑	‑
	Water Absorption	ASTM D570	%	< 0.2	< 0.1
	Mold Shrinkage	ASTM D955	%	0.4‑0.7	0.3‑0.7
Mechanical Properties	Tensile Strength	ASTM D638	MPa	~60 (GPPS)	13.8‑41.4
	Elongation at Break	ASTM D638	%	‑	15‑75
	Flexural Strength	ASTM D790	MPa	‑	13.8～55.1
	Izod Notched Impact Strength (23°C)	ASTM D256	J/m	Low (GPPS)	High (approx. 4‑fold improvement versus GPPS)
	Rockwell Hardness	ASTM D785	‑	High (GPPS)	‑
Thermal Properties	Heat‑Distortion Temperature (HDT, 1.8 MPa)	ASTM D648	°C	70‑100	‑
	Vicat Softening Temperature	ASTM D1525	°C	‑	‑
Optical Properties	Light Transmittance	‑	%	88‑92	Opaque
Electrical Properties	Volume Resistivity	ASTM D257	Ω·cm	High	‑
Flame‑Retardant Properties	UL94 Flame Rating	UL94	‑	HB (common)	HB or V‑0 (flame‑retardant grade)

Injection Molding Parameters

Process Parameter	Reference Range / Recommendation (PS)	Reference Range / Recommendation (HIPS)	Remarks & Descriptions
Drying Treatment	Normally unnecessary; if required, 80°C for 2‑3 h	Normally unnecessary; if required, 70‑80°C for 2‑3 h	PS/HIPS have low water absorption and generally do not require drying. Drying is recommended under high‑humidity environment or improper storage.
Barrel Temperature	180‑215°C	190‑240°C	Higher temperature is preferred for HIPS due to rubber content.
Mold Temperature	40‑50°C; 60‑80°C	40‑60°C	Higher mold temperature helps reduce internal stress and improve gloss.
Injection Pressure	60‑150 MPa; 200‑600 bar	Relatively high	Sufficient holding pressure and holding time are required.
Injection Speed	Fast	‑
Screw Speed	‑	‑	Avoid excessive screw speed to prevent shear overheating.
Back Pressure	‑	0.5‑1.0 MPa (general HIPS recommendation)	Appropriate back pressure facilitates melt homogenization.

Disclaimer: All above data is for reference only.