Polystyrene (PS)

Polystyrene (PS), including crystal-clear GPPS and tough HIPS, is a widely used commodity plastic offering high dimensional stability, low shrinkage, and excellent optical clarity or impact resistance. Jucheng Precision, an ISO 9001 and ISO 13485 certified manufacturer, provides custom PS injection molding tailored to strict optical and medical tolerances. Equipped with 35+ advanced molding presses (50-650T) and 25+ in-house 5-axis CNC machines, we control PS’s brittleness through precise gate designs and ejector systems. Our engineers deliver free DFM analysis within 24 hours to optimize parting lines and minimize weld marks, verified by Zeiss CMM inspection.

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Our available materials

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PS-Chi Mei PH-88S

PS-Chi Mei PH-88S (POLYREX® PH-88S) is a premium extrusion-grade high-impact polystyrene (HIPS) manufactured by Chi Mei Corporation, specifically optimized for sheet extrusion, thermoforming, and specialized molding of high-toughness containers. Featuring a low melt flow index of 2.6 g/10 min and a flexural modulus of 1,400 MPa, this grade is the industry standard for environmental stress-crack resistant (ESCR) refrigerator liners and disposable food packaging. Jucheng Precision, under ISO 9001 and IATF 16949 quality frameworks, specializes in molding PH-88S to secure uniform wall thickness. Utilizing our 25+ in-house five-axis CNC machines, we engineer robust, balanced tooling to handle its melt orientation and 0.4%-0.7% shrinkage.

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PS-Chi Mei POLYREX PG-33

PS-Chi Mei POLYREX PG-33 is a general-purpose polystyrene (GPPS) grade manufactured by Chi Mei Corporation, revered for its high optical brightness, standard melt flow (MFI 8.0 g/10 min), and lightweight density of 1.04 g/cm³. Specially formulated for standard injection molding, this grade is the global standard for high-refraction lampshades, transparent food containers, and CD jewel cases. At Jucheng Precision, an ISO 9001 and IATF 16949 certified contract manufacturer, we utilize our 25+ in-house 5-axis CNC machines to cut mirror-polished S136 stainless steel molds. This prevents weld-line defects and relieves residual molding stresses, delivering pristine, stress-free optical components verified by Zeiss CMM inspection.

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PS-Sabic HIPS 638

PS-Sabic HIPS 638 is a high-impact polystyrene (HIPS) grade manufactured by SABIC, revered for its outstanding structural toughness, excellent stiffness, and controlled melt flow (MFI 8.0 g/10 min). Polymerized with rubber-modified polybutadiene domains dispersed inside a rigid polystyrene matrix, this opaque resin is the global standard for heavy-duty appliance parts, structural toys, and electronic enclosures. At Jucheng Precision, an ISO 9001 and IATF 16949 certified manufacturer, we specialize in molding HIPS 638 without surface defects. Utilizing our 25+ in-house 5-axis CNC tooling, we optimize gate sizes and packer profiles to prevent sink marks on heavy structural ribs, delivering pristine components verified by Zeiss CMM inspection.

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PS-Trinseo STYRON 678D

PS-Trinseo STYRON 678D is an optical-grade general purpose polystyrene (GPPS) engineered by Trinseo, prized for its exceptional glass-like clarity, high heat resistance, and balanced melt moldability. Featuring a density of 1.04 g/cm³ and a stable melt flow rate of 10 g/10 min, this grade is universally specified for thin-walled containers, jewel boxes, and diagnostic labware. Jucheng Precision, under ISO 9001 and ISO 13485 frameworks, excels in processing STYRON 678D to avoid optical stress marks. Supported by our 25+ in-house five-axis CNC machines and cleanroom facilities, we implement low-stress tool paths to prevent brittle cracking during part ejection.

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PS-Trinseo STYRON A-tech 1175

PS-Trinseo STYRON A-tech 1175 is an advanced technology high impact polystyrene (HIPS) engineered by Trinseo, distinguished by its exceptional environmental stress crack resistance (ESCR) against hydrocarbons and fats, alongside robust rigidity. Featuring a density of 1.05 g/cm³ and a melt index of 2.8 g/10 min, this grade is universally specified for large refrigeration liners, home appliance accessories, and food-contact enclosures. Jucheng Precision, under IATF 16949 and ISO 9001 quality frameworks, specializes in molding STYRON A-tech 1175 to yield high structural durability. Utilizing our 35+ advanced injection presses and in-house tooling, we prevent surface weld lines and optimize wall thickness distribution, verified by Zeiss CMM inspection.

Comprehensive Polystyrene (PS) Grades We Mold

We process high-performance Polystyrene resins from leading global chemical producers, catering to both high-clarity and heavy-impact applications:

PS Material Sub-Type	Typical Brand & Grade	Key Characteristics & Advantages
GPPS (General Purpose)	• Trinseo STYRON 678D • Sabic GPPS 150 • Chi Mei PG-33 • TotalEnergies GPPS 1540	Outstanding optical clarity, high stiffness, and brilliant gloss. However, it is relatively brittle. Ideal for medical labware, plastic cutlery, cosmetic containers, and jewel boxes.
HIPS (High Impact)	• Trinseo STYRON A-tech 1175 • Sabic HIPS 638 • Chi Mei PH-88S • TotalEnergies HIPS 8260	Modified with butadiene rubber to offer high impact toughness and dimensional stability. Opaque with a matte or satin surface. Ideal for electronic housings, toys, and structural components.

Applicable Molding Processes for Polystyrene (PS)

Polystyrene’s low shrinkage and easy melt flow make it highly adaptable to multiple specialized molding methods:

Molding Process	Process Suitability & Application
Standard Injection Molding	Excellent. Highly suitable for producing rigid, high-gloss consumer goods and robust structural frames with quick cycle times.
Thin-Wall Molding	High. Polystyrene’s easy flow properties allow for the high-speed production of thin-walled cosmetic containers and food packaging cups.
Insert Molding	Good (Mostly with HIPS). Rigid metal screws or connectors can be easily molded into HIPS housings to build reliable electronic assemblies.
Overmolding / Multi-Shot	Good. HIPS is often overmolded with compatible grades of soft thermoplastic elastomers (TPE) to create durable handles and aesthetic grips.

Polystyrene (PS) Manufacturing & Tooling Guide

Polystyrene is amorphous and highly dimensionally stable, but it requires careful tooling parameters to avoid brittle cracking and surface splay:

Pre-Drying: Polystyrene has low water absorption (<0.1%). However, for high-gloss, crystal-clear GPPS applications, we pre-dry the resin at 70°C–80°C (158°F–176°F) for 1–2 hours to eliminate moisture marks.
Melt Temperature: GPPS runs between 180°C and 260°C (356°F–500°F), while HIPS operates between 190°C and 240°C (374°F–464°F). Careful melt temperature control is vital to prevent thermal degradation of HIPS rubber elements.
Mold Temperature: Kept at 30°C to 60°C (86°F–140°F). Low mold temperatures shorten cycle times, while higher mold temperatures improve surface finish and decrease internal stresses.
Ejection System Design: Because GPPS is brittle, sharp corners and high local stresses can cause cracks during ejection. We design generous draft angles (at least 1° to 1.5°) and wide ejector pins to distribute forces evenly.
Weld Line Optimization: For clear GPPS parts, weld lines will compromise both aesthetics and optical transparency. Jucheng’s tooling engineers optimize runner systems and gates using DFM software to shift weld lines to non-visible areas.

Key Application Industries for Molded PS Parts

Medical & Laboratory Diagnostics (ISO 13485): Clear petri dishes, test tubes, microplates, disposable pipettes, and diagnostic cassettes.
Consumer Electronics: TV housings, refrigerator door liners, audio cassette cases, remote control housings, and toy structural parts.
Cosmetic & Food Packaging: Highly transparent cosmetic jars, clear plastic cups, thin-walled food containers, and disposable cutlery.
Industrial & Appliance Housings: Refrigerator shelves, control panels, protective structural shells, and light-diffusing plates.

Material Properties

Density (GPPS)	1.04 - 1.06 g/cm³
Density (HIPS)	1.03 - 1.05 g/cm³
Melt Mass-Flow Rate (MFR) (200°C/5.0kg)	2.0 - 15 g/10 min
Tensile Strength at Yield (GPPS)	40 - 55 MPa
Tensile Strength at Yield (HIPS)	20 - 35 MPa
Flexural Modulus (GPPS)	3,000 - 3,400 MPa
Flexural Modulus (HIPS)	1,600 - 2,200 MPa
Izod Impact Strength (Notched, 23°C - HIPS)	70 - 120 J/m
Light Transmission (GPPS)	88 - 90 %
Melting Temperature (Softening)	90 - 105 °C
Linear Mold Shrinkage	0.3 - 0.7 %
Dielectric Strength	18 - 23 kV/mm
Volume Resistivity	1.0E+16 Ohm·cm
Maximum Part Size	1000 x 800 mm
Minimum Part Size	1 x 1 mm