| Base resin type | Suspension PVC resin for rigid extrusion or injection molding | The resin determines fusion behavior, melt strength, surface quality, and mechanical performance. | Review the technical data sheet, resin grade, polymerization process, and application suitability. |
| PVC K-value | Approximately K 65–68 for many rigid extrusion applications | A higher K-value generally improves toughness and melt strength but can increase processing difficulty. | Request the test method and confirm the value through incoming laboratory testing. |
| Compound density | Typically about 1.35–1.55 g/cm³, depending on fillers and additives | Density affects product weight, shipping cost, material consumption, and dimensional calculations. | Specify the allowable tolerance and measure finished compound samples using a recognized density method. |
| Calcium carbonate filler | Commonly about 5–15 phr in rigid compounds; application ranges vary | Filler can reduce cost and modify stiffness, but excessive loading may reduce impact resistance and surface quality. | Check loading level, particle size, moisture content, coating treatment, and dispersion. |
| Heat stabilizer system | Usually around 2–5 phr, formulation dependent; lead-free systems are widely specified | Stabilizers protect PVC against thermal degradation during processing and help maintain color and mechanical properties. | Require heavy-metal declarations, formulation consistency, and thermal-stability test results. |
| Impact modifier | Often approximately 3–10 phr for products requiring improved impact performance | Impact modifiers improve toughness, especially at low temperatures, but may affect stiffness and cost. | Test impact strength at the intended service temperature and verify weathering performance where applicable. |
| Titanium dioxide for white grades | Commonly about 3–8 phr for white or light-colored outdoor applications | It improves opacity, whiteness, and resistance to color change caused by outdoor exposure. | Evaluate color difference, opacity, weathering results, and pigment dispersion. |
| Plasticizer content | Normally none for rigid UPVC; flexible PVC uses plasticizers | Plasticizer content changes flexibility, migration behavior, dimensional stability, and regulatory requirements. | Confirm that the compound is rigid UPVC and request a restricted-substance declaration. |
| Processing temperature | Typical melt-processing range is approximately 170–210°C, depending on equipment and formulation | PVC can degrade if overheated or held too long, leading to discoloration, corrosion, and loss of strength. | Conduct a trial run and record barrel temperatures, residence time, torque, pressure, and output stability. |
| Tensile strength | Often approximately 35–55 MPa for rigid UPVC, depending on formulation and test direction | Tensile strength indicates the compound’s ability to resist pulling forces during use and installation. | Specify the applicable ISO or ASTM test standard, specimen preparation, and minimum acceptance value. |
| Vicat softening temperature | Commonly about 75–85°C for many rigid UPVC formulations | This value helps assess resistance to deformation under elevated temperature conditions. | Match the test load and heating rate to the required standard and end-use specification. |
| Charpy impact strength | Frequently within approximately 3–10 kJ/m² for rigid UPVC; formulation and temperature are critical | Impact performance is important for handling, installation, transportation, and cold-weather service. | Test notched and unnotched specimens, including the intended low-temperature condition where relevant. |
| Color and weathering | Color tolerance should be defined by ΔE or an agreed visual reference; outdoor grades require UV evaluation | Color consistency affects product appearance and can reveal processing or formulation instability. | Use retained samples, color measurements, accelerated weathering, and batch-to-batch comparison. |
| Moisture content | Should be controlled at a low, agreed level; the exact limit depends on packaging and formulation | Excess moisture can cause processing instability, surface defects, and inconsistent physical properties. | Set a maximum moisture limit and verify samples from different production lots. |
| Regulatory compliance | Typical global requirements may include REACH, RoHS, restrictions on lead and cadmium, and applicable food-contact or drinking-water rules | Compliance requirements vary by destination market and product application; non-compliance can prevent customs clearance or sale. | Request current declarations, third-party test reports, safety data sheets, and full restricted-substance documentation. |
| Quality documentation | Technical data sheet, safety data sheet, certificate of analysis, specification sheet, and batch traceability | Complete documentation supports quality control, customs procedures, audits, and repeat purchasing. | Make document submission and lot traceability contractual requirements before shipment. |
| Packaging and logistics | Moisture-resistant bags or lined bulk packaging; common bag sizes include 20–25 kg, subject to agreement | Packaging affects moisture protection, warehouse handling, pallet efficiency, and total landed cost. | Confirm net weight, pallet configuration, labeling language, container loading plan, and storage conditions. |
| Commercial evaluation | Compare total landed cost rather than material price alone | Freight, duties, testing, rejects, lead time, payment terms, and inventory carrying costs can materially change sourcing economics. | Use a landed-cost model and approve the compound only after production-scale sampling. |
