DOTP Technical Properties: Boiling Point, Density, Flash Point & More

When selecting a plasticizer for PVC applications, engineers and procurement teams need precise physical and chemical property data —not marketing claims. Dioctyl terephthalate (DOTP, CAS 6422-86-2) has become the preferred non-phthalate alternative to DOP, but reliable technical data is often scattered across incomplete sources. This guide consolidates every key property —boiling point, density, flash point, viscosity, molecular weight, solubility, refractive index, and storage guidelines —in one reference, with verified data from Shandong Changxing's DOTP Safety Data Sheet (Version V2.0.0.1, Report No. THSD25121980034EN). For the complete safety classification and toxicology profile, see our DOTP MSDS and Safety Data Sheet guide.

DOTP at a Glance: Basic Identification

A common source of confusion: despite the word "phthalate" in its name, DOTP is not a phthalate. Phthalates are ortho-phthalic acid esters; DOTP is a terephthalic acid ester (para-isomer). This structural difference eliminates the endocrine-disruption concerns associated with DOP and other ortho-phthalates, making DOTP compliant with REACH Entry 51/52, US CPSIA, and EU toy safety regulations.

Complete Physical and Chemical Properties

The following data is drawn from Shandong Changxing's official SDS (UN GHS 8th revised edition) and supplemented with industry-standard reference values where applicable.

Boiling Point: Why 383 °C Matters for PVC Processing

DOTP's boiling point of 383 °C is one of its most technically significant properties. During PVC compounding, the material is typically processed at 150–90 °C. With a boiling point more than 190 °C above the maximum processing temperature, DOTP exhibits virtually zero volatility loss during manufacturing.

This has three practical consequences:

• Consistent formulation ratios: Unlike lower-boiling plasticizers that evaporate during mixing, DOTP stays in the compound at the designed concentration, ensuring predictable mechanical properties in the finished product.
• Reduced fume generation: Lower volatility means fewer plasticizer fumes in the workplace, improving air quality for operators and reducing the need for expensive ventilation systems.
• Long-term product stability: Products plasticized with DOTP show minimal plasticizer migration and weight loss over years of service, especially important for wire insulation, flooring, and roofing membranes exposed to elevated temperatures.

Flash Point ≥10 °C: Safety Advantage

The flash point of ≥10 °C (open cup method) places DOTP firmly in the non-flammable category. For comparison, many industrial solvents have flash points below 60 °C, requiring explosion-proof equipment and nitrogen blanketing. DOTP's high flash point means:

• No special fire-suppression systems required in storage areas
• No flammable-material handling permits needed in most jurisdictions
• Lower insurance premiums for warehouses storing DOTP versus low-flash-point chemicals
• Safe transport as non-dangerous goods under IMDG, IATA, and ADR regulations

This safety profile directly reduces operational costs and regulatory burden —a practical advantage that procurement teams often overlook when comparing only unit prices.

Density and Viscosity: Processing Implications

DOTP's density of 0.980—.986 g/cm³ and kinematic viscosity of ~80–0 cSt at 20 °C are both slightly higher than DOP (density ~0.985 g/cm³, viscosity ~78 cSt). These differences have real processing implications:

• Plastisol stability: Higher viscosity translates to better suspension stability in PVC plastisols, reducing settling during storage and improving coating uniformity in spread-coating applications (artificial leather, flooring).
• De-aeration: The slightly higher viscosity can slow de-aeration in plastisol processing. This is typically addressed by adjusting mixer speed or using a vacuum de-aeration step.
• Dosing accuracy: The consistent density allows precise volumetric dosing in automated compounding lines, with minimal batch-to-batch variation.

Solubility and Compatibility

DOTP is practically insoluble in water (<0.01 g/L at 20 °C) but fully miscible with common organic solvents and highly compatible with PVC resin. Its high log Kow (~8.40) indicates strong lipophilicity and excellent polymer-matrix affinity.

In practical terms, DOTP is compatible with:

• PVC homopolymer and copolymer resins
• Other plasticizers (can be blended with DINP, TOTM, or epoxidized soybean oil)
• Standard PVC stabilizers (Ca-Zn, Ba-Zn, tin-based)
• Fillers and pigments commonly used in PVC formulations

Water insolubility means DOTP-plasticized products resist leaching in humid or wet environments —critical for PVC flooring, geomembranes, and cable insulation exposed to moisture.

DOTP vs DOP: Key Property Differences

While DOTP and DOP share the same molecular formula (C₂₄H₃₈O₂ and nearly identical physical properties, the regulatory and safety differences are decisive. DOTP's non-phthalate classification, unrestricted REACH status, and superior plastisol stability make it the logical choice for new product development and DOP substitution programs. For a deeper comparison, see our DOTP vs DOP comparison guide.

DOTP Storage Guide

Proper storage preserves DOTP's quality throughout the supply chain. Based on the SDS handling and storage recommendations:

• Temperature: Store at ambient temperature (5–0 °C). DOTP's melting point of ∆8 °C means it remains liquid even in cold climates; no heating is required.
• Containers: Keep in original sealed containers. Compatible with carbon steel, stainless steel, and HDPE. Avoid copper and its alloys.
• Ventilation: No special ventilation required (negligible vapour pressure <0.01 Pa). General room ventilation is sufficient.
• Moisture: DOTP is practically insoluble in water, but prolonged water contact should be avoided to prevent contamination. Keep containers tightly sealed.
• Shelf life: When stored properly in sealed containers, DOTP has a shelf life of 24+ months with no significant change in properties.
• Segregation: No special segregation from other non-hazardous chemicals required. DOTP is not classified as dangerous goods for transport or storage.
• Fire protection: No special fire-suppression systems needed. Standard water spray, dry chemical, or foam extinguishers are suitable if a fire involves DOTP.

Quality Specifications: What to Verify

When purchasing DOTP, verify these key specifications against the supplier's Certificate of Analysis (COA):

Always request a batch-specific COA and verify that the data matches the specifications above. For export to the EU and US, also request SGS test reports confirming phthalate-free status, EN 71-3 compliance, and PFAS-free certification.

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References and External Resources

• PubChem —Dioctyl Terephthalate (CAS 6422-86-2)
• ChemSpider —DOTP Chemical Structure
• UN Globally Harmonized System (GHS) —9th Revised Edition