Coupling Agents
For polymer blends and filled formulations.
Polymer Diagnostics & Research Center · Delhi
Better polymers start with answers.
When a polymer fails, drifts off specification or needs to do more, we connect testing with a practical solution. From recycled resin and MFI control to performance additives, our work is built for the production floor.
Testing · Diagnosis · Formulation · Process support
How we workFrom problem to production
Applied science
Understand the failureMaterial, process and end-use requirements
Test what mattersTargeted measurements and root-cause analysis
Put the fix to workFormulation, additive or process trial
A useful result is one you can check and repeat on your line.
Material challenges, made workable.For processors, recyclers, compounders and manufacturers working with virgin or recycled polymers.
What we do
One partner from diagnosis to improvement.
Choose the starting point that fits your problem. We can investigate a failure, help refine a formulation or identify an additive approach.
01 / Test
Find the cause
Polymer identification, melt flow, thermal, mechanical and composition testing focused on the question you need answered.
Explore testing → 02 / ImproveRecover performance
Address MFI drift, lost strength, processing issues and inconsistent recycled streams with a workable formulation or process change.
See our expertise → 03 / AddChoose the right additive
Explore coupling agents, flame retardants, silicone additives, foaming agents and our lamination adhesion additive.
View products →Applications
Built around the problem you are solving.
Real materials often need more than a standard test result. Explore the areas where we connect analysis with processing decisions.
Featured addition
Lamination adhesion additive
For extrusion coating on paper, woven sacks and aluminium foil. Begin with a 2% addition trial, with scope to use reprocessed polymer and higher filler loading while checking adhesion for your substrate and line.
See the product details →Our method
Clear steps. Measurable decisions.
The aim is to make the next plant trial more informed, with the relevant properties checked against your application.
01
Share the issue
Tell us the material, process, specifications and what changed.
02
Diagnose
Select relevant tests and identify the likely cause.
03
Recommend
Develop an additive, blend or processing approach.
04
Validate
Check the proposed solution against the original target.
Start a conversation
Tell us what your material needs to do.
Whether you have an off-spec batch, a recycled resin challenge or a new application, we can help define the next useful test or trial.
Submit a caseProducts
Our existing additive range, with the new lamination adhesion additive added below.
Existing additive range
Flame Retardants
Additive solutions for flame-retardant formulations.
Silicone Additives
Silicone-based performance additives for polymer processing.
Oxo-biodegradable Additive Systems
Part of our sustainability formulation work.
Exothermic Foaming Agents
For polymer foaming applications and formulation trials.
MFI Modification
Solutions to adjust melt flow for processing and recycling.
New addition · Extrusion coating & lamination
Lamination Adhesion Additive
An adhesion additive for extrusion coating and lamination on paper, woven sacks and aluminium foil. Start with 2% addition to the polymer coating formulation.
Without corona treatmentDesigned to promote adhesion on suitable substrates without a separate corona treatment step.
Higher filler loadingExplore increased filler levels while maintaining the bond needed for your application.
Reprocessed materialSupports trials using reprocessed polymer in the coating blend.
Three substratesApplications include paper, PP woven sacks and aluminium foil.
Confirm dosage, peel strength and end-use performance in a production trial; results depend on the polymer, substrate, filler level and line conditions.
What we treat
Most polymer problems show up the same way on the plant floor. Here's what we usually find underneath, and where we start.
Inconsistent melt flow
Batch-to-batch variation in MFI causes fill problems, warping, or rejected lots — often from feedstock blending or degradation during reprocessing.
Rheology testing & feedstock audit
Lost mechanical properties
Recycled or reprocessed resin loses impact strength or tensile performance versus the virgin material it's replacing.
Property recovery & additive package design
Unexplained discoloration or odor
Yellowing, streaking, or off-odor in finished parts, usually traced to contamination, thermal degradation, or incompatible additives.
Compositional analysis & contamination ID
Field failures & cracking
Parts that pass QC but fail in the field — stress cracking, brittleness, or premature aging under real-world conditions.
Failure analysis & root-cause investigation
Underperforming recycled content
A recycled stream that won't hit the performance needed to replace virgin resin in a spec, blocking a sustainability or cost target.
Performance modification & blend optimization
How we work
Every case moves through the same four stages, whether it's a one-off failure or an ongoing formulation project.
01
Intake
You send samples and describe what's going wrong on the line — a defect, a spec miss, a customer complaint. We define what "fixed" looks like before testing starts.
02
Diagnose
We run the testing needed to find the actual cause — not just confirm the symptom — comparing against spec, virgin material, or a reference sample.
03
Prescribe
You get a specific, commercially workable fix: an additive package, a process change, a blend ratio — something your line can actually run.
04
Validate
We test the treated material or trial run against the original target so you can confirm the fix before committing to production volume.
Where we specialize
Applied polymer science across sustainability, recycling, additives and process — the problems we're asked to solve most often.
Sustainability
Bio-compostable & Oxo-bio
Bio-compostable plastic development
Oxo-biodegradable additive systems
Recycling
Recovery & MFI Modification
Strength & property recovery in recycled resin
Melt flow index (MFI) modification
Additives
Performance Additives
Coupling agents
Flame retardants
Silicone additives
Formulation
Foaming & Elastomers
Exothermic foaming agents
Elastomer & rubber compounding
R&D
Polymer Innovation
New formulation development
Custom material design
Advisory
Consultancy
Polymer consultancy
Project & plant consultancy
Testing capabilities
Full-service polymer testing, run in support of a diagnosis — not as a menu of standalone lab services.
Melt flow testing in progress at our Delhi lab
Melt Flow Index (MFI) tester with live data capture
FTIR Spectrometer
Resin identification, contaminant screening
Melt Flow Index Tester
MFI/MVR — the real tester in our Delhi lab
DSC / TGA Analyzer
Melting point, crystallinity, degradation
Universal Tensile Tester
Tensile, flexural, impact, hardness
Muffle Furnace
Ash content, filler quantification
Spectrophotometer
Color (L*a*b*), haze, gloss
Optical Microscope
Fractography, foreign material ID
Analytical Balance
Density, specific gravity, bulk density
Composting Chamber
Biodegradability & disintegration testing
All tests at a glance
Polymer Identification
- FTIR spectroscopy
- DSC cross-check
- Density & burn-test triage
Rheological
- Melt flow index (MFI/MVR)
- Capillary & rotational rheometry
- Viscosity & shear response
Thermal
- DSC — melting, crystallinity
- TGA — degradation, filler content
- HDT & Vicat softening point
Mechanical
- Tensile & flexural strength
- Impact resistance (Izod/Charpy)
- Hardness (Shore A / Shore D)
- Fatigue & long-term stress
Compositional
- Contaminant & foreign-material screening
- Ash & filler content
- Additive & polymer blend ratios
Color & Optical
- Color measurement (L*a*b*)
- Haze & clarity
- Gloss
Failure Analysis
- Microscopy & fractography
- Foreign material identification
- Field-vs-spec comparison testing
Physical Properties
- Specific gravity
- Density
- Bulk density
- Mesh size / granule uniformity
Bio-compostable Testing
- Biodegradability (IS 17088 / ASTM D6400)
- Disintegration under composting
- Residue & ecotoxicity screening
First Step
Polymer Identification
FTIR spectroscopy (resin fingerprinting)Matches the sample’s infrared spectrum against known resin fingerprints to confirm exactly what polymer you have
DSC cross-check (melt/crystallization point)Confirms resin identity by matching melting and crystallization temperatures against reference values
Density & burn-test triageFast, low-cost first checks that narrow down the polymer family before instrumental testing
Flow & Processing
Rheological
Melt flow index (MFI/MVR)Measures how much resin flows through a die under a fixed load — the standard check for batch-to-batch processability
Capillary & rotational rheometryMeasures viscosity across a range of shear rates, closer to real extrusion or injection conditions than MFI alone
Viscosity & shear responseShows how the melt thins or thickens under processing stress, flagging inconsistent flow behavior
Heat & Stability
Thermal
DSC — melting, crystallinityMeasures melting point and % crystallinity, which drive strength, shrinkage, and processing window
TGA — degradation, filler contentHeats the sample to track weight loss, revealing degradation temperature and inorganic filler content
HDT & Vicat softening pointMeasures the temperature at which the material starts to deform under load or heat
Strength & Durability
Mechanical
Tensile & flexural strengthMeasures how much force the material withstands before stretching, bending, or breaking
Impact resistance (Izod/Charpy)Measures toughness — how well the part absorbs a sudden impact without cracking
Hardness (Shore A / Shore D)Measures surface resistance to indentation, grading rigidity from soft elastomers to hard plastics
Fatigue & long-term stressTests how the material holds up under repeated or sustained loading over time
Chemistry & Purity
Compositional
Contaminant & foreign-material screeningIdentifies unexpected particles or foreign polymers mixed into the resin
Ash & filler contentBurns off the organic polymer to quantify inorganic filler or contamination left behind
Additive & polymer blend ratiosQuantifies the actual ratio of additives or blended resins against what the spec sheet claims
Appearance
Color & Optical
Color measurement (L*a*b*)Quantifies color numerically so batch-to-batch shifts can be caught and matched precisely
Haze & clarityMeasures how much light scatters through the material — critical for transparent packaging and optical parts
GlossMeasures surface shine, which affects both appearance and perceived quality
Root Cause
Failure Analysis
Microscopy & fractographyExamines the fracture surface under magnification to see exactly how and where a part failed
Foreign material identificationIdentifies whatever caused the failure — a contaminant, a void, an unmelted particle
Field-vs-spec comparison testingCompares the failed part directly against its original specification to pinpoint what changed
Bulk Properties
Physical Properties
Specific gravityA quick ratio-based check of resin identity and consistency against a known reference
DensityConfirms resin type and detects voids, fillers, or incomplete mixing
Bulk densityMeasures how pellets or powder pack and flow — important for feeding and dosing equipment
Mesh size / granule uniformity in reprocessed danaChecks that reprocessed pellets are sized consistently for smooth, predictable feeding
Compostability
Bio-compostable Testing
Biodegradability (IS 17088 / ASTM D6400)Confirms the material breaks down under composting conditions to the certified standard
Disintegration under composting conditionsPhysically tracks how completely the material breaks apart during a real composting cycle
Residue & ecotoxicity screeningConfirms no harmful residue or toxicity remains in the compost after breakdown
Book a Consultation
Not sure which tests fit your case?
Talk it through directly with our CEO before you send a sample — we'll help you scope the right tests so you're not paying for ones you don't need.
Harshita
Chief Executive Officer
Frequently asked questions
Common technical questions we get from processors, recyclers, and manufacturers — answered directly.
What happens if you use high-MFI HDPE in pipe manufacturing?
High-MFI (low molecular weight) HDPE doesn't have enough long-chain "tie molecules" to hold a PE80/PE100 pressure rating over its design life. It typically fails long-term hydrostatic strength and ESCR (environmental stress crack resistance) testing even when short-term tensile numbers look fine, and its low melt strength causes sagging and inconsistent wall thickness during extrusion.
What are the benefits of using low or fractional MFI HDPE for pipe manufacturing?
Low/fractional MFI resin gives long-term hydrostatic strength (holding the pipe's PE80/PE100 rating over its full 50-year design life), better ESCR, higher impact strength, higher melt strength for consistent wall thickness during extrusion, better resistance to rapid crack propagation (RCP), and slower long-term degradation.
What does DSC mean in polymer testing?
DSC stands for Differential Scanning Calorimetry — a thermal analysis technique that measures how much heat a material absorbs or releases as it's heated or cooled. It reveals melting point, crystallization temperature, percentage crystallinity, and can flag contamination or blending with another polymer.
How is an unknown polymer identified?
Identification usually starts with quick, low-cost checks — density and a burn test — to narrow down the polymer family, followed by FTIR spectroscopy for a definitive resin fingerprint, cross-checked against DSC melting and crystallization behavior.
Why does HDPE pipe need low MFI while some PP applications need high MFI?
The two use cases need opposite properties. HDPE pipe needs low MFI (high molecular weight) for long-term pressure resistance and slow crack growth. PP used in injection molding — especially recycled PP film and raffia scrap — often needs higher MFI so the melt flows easily into thin-wall or large-format molds. That's why Polymer Doctor's MFI Reducer lowers MFI for HDPE pipe, while the PP MFI Enhancer raises MFI for recycled PP molding.
What is the SPI resin identification code?
The SPI (Society of the Plastics Industry) resin identification code is the number 1–7 inside the recycling triangle on plastic products, introduced in 1988. It indicates the base resin type — for example, 1 = PET, 2 = HDPE, 5 = PP — to help with sorting and recycling.
How does Polymer Doctor's testing process work?
Every case moves through four stages: Intake (you send samples and describe the problem), Diagnose (targeted testing to find the actual root cause, not just the symptom), Prescribe (a specific, commercially workable fix — an additive package, a process change, a blend ratio), and Validate (confirming the fix against your original target before you commit to production volume).
Does recycled or reprocessed polymer need different testing than virgin resin?
Yes. Reprocessing and repeated heat cycles typically shift MFI, reduce mechanical properties like impact strength, and can introduce contamination — so reprocessed material needs property-recovery and batch-consistency testing that virgin resin usually doesn't.
What standard governs bio-compostable plastic testing?
Bio-compostable and compostable plastics are tested against IS 17088 in India and ASTM D6400 internationally, covering biodegradability, disintegration under real composting conditions, and residue and ecotoxicity screening.
Polymer guide
Identification specs and origin for the resins we see most — useful for a quick sanity check before a sample goes to the lab.
Density, melting behavior, and resin identification code (the number inside the recycling triangle) are the fastest first checks on an unknown sample. FTIR and DSC (see Testing Capabilities) confirm what these numbers suggest.
| Polymer | Density (g/cm³) | Melting Point (°C) | Resin Code | Invented | Inventor | Origin | Common Uses |
|---|---|---|---|---|---|---|---|
| Low-Density Polyethylene LDPE | 0.910–0.940 | 105–115 | 4 | 1933 | Eric Fawcett & Reginald Gibson | ICI, Northwich, England | Film, bags, squeeze bottles |
| High-Density Polyethylene HDPE | 0.941–0.965 | 120–130 | 2 | 1953 | Karl Ziegler; commercialized by Phillips Petroleum (Hogan & Banks) | Germany / USA | Milk jugs, crates, pipes, drums |
| Polypropylene PP | 0.895–0.920 | 160–166 | 5 | 1954 | Giulio Natta | Politecnico di Milano / Montecatini, Italy | Caps, containers, automotive parts, textiles |
| Polyvinyl Chloride PVC | 1.16–1.45 | 160–210 (processing) | 3 | 1926 (usable form) | Waldo Semon, B.F. Goodrich (first prepared 1872, Eugen Baumann) | Akron, USA (Germany) | Pipes, cables, profiles, flooring |
| Polystyrene PS | 1.04–1.05 | ≈100 (Tg, amorphous) | 6 | 1839 (discovered) / 1930s (commercial) | Eduard Simon (commercialized by IG Farben) | Berlin, Germany | Packaging, disposable cutlery, insulation |
| Polyethylene Terephthalate PET | 1.38–1.41 | 250–260 | 1 | 1941 | John Rex Whinfield & James Dickson | Calico Printers’ Assoc., Manchester, England | Bottles, fibers, food packaging |
| Polycarbonate PC | 1.20–1.22 | ≈150–155 (Tg 147, amorphous) | 7 | 1953 | Hermann Schnell | Bayer, Uerdingen, Germany | Eyewear lenses, CDs, safety equipment |
| Nylon 6,6 (Polyamide) PA | 1.13–1.15 | 255–265 | 7 | 1935 | Wallace Carothers | DuPont, Wilmington, USA | Fibers, gears, bearings, automotive parts |
| Acrylonitrile Butadiene Styrene ABS | 1.04–1.07 | ≈105 (Tg, amorphous) | 7 | 1948 (patented) / 1954 (commercial) | United States Rubber Co.; commercialized by Borg-Warner | USA | Appliance housings, automotive interiors, pipe fittings |
| Polymethyl Methacrylate (Acrylic) PMMA | 1.17–1.20 | ≈100–105 (Tg, amorphous) | 7 | 1933 | Otto Röhm | Röhm & Haas, Darmstadt, Germany | Signage, lenses, sheets, aircraft glazing |
| Polylactic Acid PLA | 1.24–1.25 | 150–160 | 7 | 1932 (synthesized) / 2002 (commercial scale) | Wallace Carothers (commercialized by Cargill / NatureWorks) | DuPont, USA (Nebraska, USA) | Compostable packaging, 3D printing, disposable cutlery |
| Polyurethane PU | 0.02–1.25 (formulation-dependent) | Thermoset — no single melt point | 7 | 1937 | Otto Bayer | Bayer AG, Leverkusen, Germany | Foams, elastomers, coatings, adhesives |
| Ethylene Vinyl Acetate EVA | 0.92–0.95 | 65–95 | 7 | 1938 / 1960 | ICI; commercialized by DuPont | United Kingdom / USA | Foam footwear soles, hot-melt adhesives |
| Polyoxymethylene (Acetal) POM | 1.41–1.42 | 165–175 | 7 | 1956 | DuPont | USA | Gears, bearings, zippers, precision parts |
| Polytetrafluoroethylene PTFE | 2.14–2.20 | ≈327 (softening) | 7 | 1938 | Roy Plunkett | DuPont, New Jersey, USA | Non-stick coatings, gaskets, seals |
| Thermoplastic Polyurethane TPU | 1.10–1.25 | 150–220 | 7 | 1952 / 1959 | Charles Schollenberger | B.F. Goodrich, Ohio, USA | Phone cases, hoses, industrial wheels |
| EPDM Rubber EPDM | 0.86–0.87 | Thermoset — no melt point | 7 | Early 1960s | DuPont & others | USA | Window/door seals, roofing membranes |
| Natural Rubber NR | 0.91–0.92 | Thermoset — no melt point | 7 | Vulcanized 1839 | Charles Goodyear (vulcanization) | USA | Tires, footwear, seals |
| Nitrile Rubber NBR | 0.98–1.00 | Thermoset — no melt point | 7 | 1930/1931 | Erich Konrad & Eduard Tschunkur | IG Farben, Germany | Fuel/oil hoses, gaskets, gloves |
| Silicone Rubber Si | 1.10–1.60 | Thermoset — no melt point | 7 | 1943 | Dow Corning Corporation | USA | Medical devices, bakeware, seals |
| Polybutylene Adipate Terephthalate PBAT | 1.21–1.27 | 110–120 | 7 | 1998 | BASF (as Ecoflex®) | Germany | Compostable bags, mulch film, flexible packaging |
Resin identification codes follow the SPI (Society of the Plastics Industry) system introduced in 1988. Density and melting-point ranges are typical for unmodified, unfilled resin — fillers, plasticizers, and reprocessing can shift these values, which is exactly what our testing confirms on your actual sample.
Detailed polymer profiles
Identification, solubility, specification standards, processing parameters, and verified invention history for each polymer — including elastomers and rubbers alongside the standard thermoplastics.
Low-Density Polyethylene LDPE
Resin Code 4Identification
Density 0.910–0.940 g/cm³; softens 105–115°C; burns with blue base & yellow tip, drips like candle wax, faint paraffin smell; floats in water
Solubility
Insoluble in common solvents at room temperature; swells/dissolves in hot xylene, toluene or decalin above 80°C; resistant to acids, alkalis, alcohols
Specification
ASTM D1248 / IS 7328 — density per ASTM D792, melt flow per ASTM D1238
Processing Parameters
Melt temp 160–240°C; non-hygroscopic, no pre-drying required; mold/chill temp 20–50°C
Invented
1933 — Eric Fawcett & Reginald Gibson, ICI, Northwich, England
Common Uses
Film, bags, squeeze bottles
High-Density Polyethylene HDPE
Resin Code 2Identification
Density 0.941–0.965 g/cm³; melts 120–130°C; burns like LDPE (drips, paraffin smell) but sinks slower / near-neutral buoyancy vs. LDPE which floats
Solubility
Resistant to most solvents, acids and alkalis at room temperature; dissolves in hot xylene or decalin above 100°C
Specification
ASTM D4976 / IS 7328 — density per ASTM D792, melt flow per ASTM D1238
Processing Parameters
Melt temp 200–280°C; non-hygroscopic, no pre-drying required; mold temp 20–60°C
Invented
1953 — Karl Ziegler, Germany; commercialized by Phillips Petroleum (Hogan & Banks), USA
Common Uses
Milk jugs, crates, pipes, drums
Polypropylene PP
Resin Code 5Identification
Density 0.895–0.920 g/cm³; melts 160–166°C; burns with blue base & yellow tip, drips, slight sweet odor; floats in water
Solubility
Resistant to most acids, alkalis and alcohols at room temperature; dissolves in hot xylene, decalin or tetralin above 100°C
Specification
ASTM D4101 / IS 10891 — density per ASTM D792, melt flow per ASTM D1238
Processing Parameters
Melt temp 220–280°C; non-hygroscopic (drying recommended for regrind); mold temp 20–60°C
Invented
1954 — Giulio Natta, Politecnico di Milano / Montecatini, Italy
Common Uses
Caps, containers, automotive parts, textiles
Polyvinyl Chloride (rigid) PVC
Resin Code 3Identification
Density 1.16–1.45 g/cm³; softens 160–210°C (amorphous, no sharp melt); burns only in flame & self-extinguishes, green flame edge on copper wire, sharp HCl odor; sinks in water
Solubility
Soluble in THF, cyclohexanone, MEK; resistant to alcohols, mineral oils, dilute acids/alkalis
Specification
ASTM D1784 / IS 4985 (pipe grade) — density per ASTM D792
Processing Parameters
Melt temp 160–210°C (narrow window — degrades above ~200°C without stabilizer); dry only if hygroscopic plasticizer present; mold temp 20–60°C
Invented
1926 (usable form) — Waldo Semon, B.F. Goodrich, Akron, USA (first prepared 1872, Eugen Baumann, Germany)
Common Uses
Pipes, cables, profiles, flooring
Polystyrene PS
Resin Code 6Identification
Density 1.04–1.05 g/cm³; softens ≈100°C (Tg, amorphous); burns with orange, sooty flame, sweet styrene odor; sinks in water
Solubility
Soluble in toluene, acetone, MEK, THF; resistant to water, dilute acids/alkalis, alcohols
Specification
ASTM D4549 / IS 6165 — density per ASTM D792
Processing Parameters
Melt temp 180–260°C; non-hygroscopic, drying optional; mold temp 10–60°C
Invented
1839 (discovered) — Eduard Simon, Berlin, Germany; commercialized 1930s by IG Farben, Germany
Common Uses
Packaging, disposable cutlery, insulation
Polyethylene Terephthalate PET
Resin Code 1Identification
Density 1.38–1.41 g/cm³; melts 250–260°C; burns sooty orange, self-extinguishes, sweet aromatic odor; sinks in water
Solubility
Soluble in phenol/TCE mixtures, hexafluoroisopropanol; resistant to dilute acids, alcohols, most solvents at room temperature
Specification
ASTM D5927 / IS 15410 (bottle grade) — intrinsic viscosity per ASTM D4603
Processing Parameters
Melt temp 260–290°C; must be pre-dried — hygroscopic, <0.005% moisture — to prevent hydrolytic degradation; mold temp 10–140°C
Invented
1941 — John Rex Whinfield & James Dickson, Calico Printers’ Association, Manchester, England
Common Uses
Bottles, fibers, food packaging
Polycarbonate PC
Resin Code 7Identification
Density 1.20–1.22 g/cm³; softens ≈150–155°C (Tg 147°C, amorphous); burns sooty yellow, self-extinguishes, faint phenolic odor; sinks in water
Solubility
Soluble in dichloromethane, chloroform; resistant to dilute acids/alcohols; attacked by strong alkalis and some ketones/esters (stress-cracking risk)
Specification
ASTM D3935 / IS 14434 — density per ASTM D792
Processing Parameters
Melt temp 280–320°C; must be pre-dried — hygroscopic, <0.02% moisture; mold temp 80–120°C
Invented
1953 — Hermann Schnell, Bayer, Uerdingen, Germany
Common Uses
Eyewear lenses, CDs, safety equipment
Nylon 6,6 (Polyamide) PA
Resin Code 7Identification
Density 1.13–1.15 g/cm³; melts 255–265°C; burns blue base, self-extinguishes, burnt-hair/celery-like odor; sinks in water
Solubility
Soluble in formic acid, phenol, cresols; resistant to hydrocarbons, oils, most organic solvents; attacked by strong acids
Specification
ASTM D4066 / IS 11810 — density per ASTM D792
Processing Parameters
Melt temp 260–290°C; must be pre-dried — highly hygroscopic, <0.2% moisture; mold temp 60–120°C
Invented
1935 — Wallace Carothers, DuPont, Wilmington, USA
Common Uses
Fibers, gears, bearings, automotive parts
Acrylonitrile Butadiene Styrene ABS
Resin Code 7Identification
Density 1.04–1.07 g/cm³; softens ≈105°C (Tg, amorphous); burns yellow with black smoke, rubbery/acrylonitrile odor; sinks in water
Solubility
Soluble in acetone, MEK, esters; resistant to dilute acids/alkalis, water; attacked by concentrated acids and some ketones (stress-cracking risk)
Specification
ASTM D4673 / IS 13360 — density per ASTM D792
Processing Parameters
Melt temp 210–260°C; mildly hygroscopic — drying recommended, <0.1% moisture; mold temp 40–80°C
Invented
1948 (patented) — United States Rubber Co., USA; commercialized 1954 by Borg-Warner, USA
Common Uses
Appliance housings, automotive interiors, pipe fittings
Polymethyl Methacrylate (Acrylic) PMMA
Resin Code 7Identification
Density 1.17–1.20 g/cm³; softens ≈100–105°C (Tg, amorphous); burns with a crackling sound, blue-yellow flame, distinctive fruity odor; sinks in water
Solubility
Soluble in acetone, toluene, ethyl acetate; resistant to water, dilute acids/alkalis, alcohols
Specification
ASTM D788 / IS 7818 — density per ASTM D792
Processing Parameters
Melt temp 210–250°C; hygroscopic — drying recommended, <0.1% moisture; mold temp 40–80°C
Invented
1933 — Otto Röhm, Röhm & Haas, Darmstadt, Germany
Common Uses
Signage, lenses, sheets, aircraft glazing
Polylactic Acid PLA
Resin Code 7Identification
Density 1.24–1.25 g/cm³; melts 150–160°C; burns weakly, self-extinguishes off-flame, faint sweet/caramel odor; sinks in water
Solubility
Soluble in chloroform, dioxane, hot ethyl acetate; resistant to water and dilute acids at room temperature; hydrolyzes under heat + moisture over time
Specification
ASTM D6400 (compostability) / IS 17088 — density per ASTM D792
Processing Parameters
Melt temp 190–220°C (narrow, heat-sensitive); must be pre-dried — hygroscopic, <0.025% moisture, to prevent hydrolysis in the melt; mold temp 20–60°C
Invented
1932 (synthesized) — Wallace Carothers, DuPont, USA; commercial scale 2002 — Cargill / NatureWorks, Nebraska, USA
Common Uses
Compostable packaging, 3D printing, disposable cutlery
Polyurethane PU
Resin Code 7Identification
Density 0.02–1.25 g/cm³ (formulation-dependent, foam to solid elastomer); thermoset — no single melt point, chars with acrid nitrogen odor on burning
Solubility
Cured (thermoset) grades are insoluble/infusible; thermoplastic PU (TPU) variants soluble in DMF, THF
Specification
ASTM D3574 (flexible foam) / ASTM D2240 (hardness) — density per ASTM D792
Processing Parameters
Reaction-processed, not melt-processed — component temps typically 20–60°C at mixing, mold temp 40–60°C
Invented
1937 — Otto Bayer, Bayer AG, Leverkusen, Germany
Common Uses
Foams, elastomers, coatings, adhesives
Ethylene Vinyl Acetate EVA
Resin Code 7Identification
Density 0.92–0.95 g/cm³ (varies with VA content); melts 65–95°C, falling as VA% rises; burns yellow with a distinctive vinegar (acetic acid) odor; floats / near-neutral in water
Solubility
Swells or dissolves in hot toluene or xylene; resistant to water and dilute acids/alkalis at room temperature
Specification
ASTM D1922 / D3182 (film); VA content per ASTM D5594; density per ASTM D792
Processing Parameters
Melt temp 120–180°C (low, heat-sensitive at high VA%); non-hygroscopic; mold temp 20–40°C
Invented
1938 (patented) — ICI, United Kingdom; commercialized 1960 as Elvax by DuPont, USA
Common Uses
Foam footwear soles, hot-melt adhesives, flexible packaging, solar-panel encapsulant
Polyoxymethylene (Acetal) POM
Resin Code 7Identification
Density 1.41–1.42 g/cm³; melts 165–175°C; burns with a blue flame and a strong, irritating formaldehyde odor; sinks in water
Solubility
Resistant to almost all common solvents, fuels and oils at room temperature; attacked by strong acids
Specification
ASTM D6100 — density per ASTM D792
Processing Parameters
Melt temp 190–220°C (narrow window — degrades above ~240°C, releasing formaldehyde gas); drying recommended; mold temp 60–120°C
Invented
1956 (patented) — DuPont, USA (building on Hermann Staudinger’s 1920s formaldehyde-polymer research, Germany); commercialized 1960 as Delrin
Common Uses
Gears, bearings, zippers, precision parts
Polytetrafluoroethylene PTFE
Resin Code 7Identification
Density 2.14–2.20 g/cm³ (unusually high — a quick identifier); does not melt conventionally, softens ~327°C; virtually non-combustible; sinks in water
Solubility
Insoluble in virtually all solvents, acids and alkalis — chemical inertness is its defining trait
Specification
ASTM D4894 / D4895 — density per ASTM D4895
Processing Parameters
Cannot be melt-processed like typical thermoplastics — sintered from powder at 360–380°C or paste-extruded
Invented
1938 — Roy Plunkett, DuPont, New Jersey, USA
Common Uses
Non-stick coatings, gaskets, seals, chemical-resistant linings
Thermoplastic Polyurethane TPU
Resin Code 7Identification
Density 1.10–1.25 g/cm³; softens 150–220°C depending on hardness grade; burns yellow, self-extinguishes, sweetish/acrid odor; sinks in water
Solubility
Soluble in DMF, THF; resistant to oils and greases (ester-based grades more oil-resistant than ether-based)
Specification
ASTM D2240 (Shore A/D hardness) — density per ASTM D792
Processing Parameters
Melt temp 180–220°C; must be pre-dried — hygroscopic, <0.05% moisture; mold temp 20–50°C
Invented
1952 (patented) / 1959 (commercial, Estane) — Charles Schollenberger, B.F. Goodrich, Ohio, USA
Common Uses
Phone cases, hoses, industrial wheels, footwear
EPDM Rubber EPDM
Resin Code 7Identification
Density 0.86–0.87 g/cm³ (unfilled); thermoset once vulcanized, no melt point; burns slowly, tends to self-extinguish, faint burnt-rubber odor; floats in water
Solubility
Swells in nonpolar solvents (toluene, hexane); resistant to water, steam, polar solvents, ozone and weathering — its defining trait
Specification
ASTM D2000 (classification) / ASTM D412 (tensile); Shore A hardness per ASTM D2240
Processing Parameters
Compression/injection/transfer molded and vulcanized at 150–200°C; not melt-reprocessable once cured
Invented
Early 1960s — DuPont and other chemical companies, USA (building on Ziegler-Natta catalyst chemistry)
Common Uses
Window/door seals, roofing membranes, radiator hoses, gaskets
Natural Rubber NR
Resin Code 7Identification
Density 0.91–0.92 g/cm³; thermoset once vulcanized, no melt point; burns readily, sooty yellow flame, characteristic burnt-rubber odor; floats in water
Solubility
Swells/dissolves in toluene, gasoline and other nonpolar solvents; resistant to water, dilute acids/alkalis; poor resistance to oils and fuels
Specification
ASTM D1076 / IS 3660 (raw rubber grades); Shore A hardness per ASTM D2240
Processing Parameters
Milled, compounded and vulcanized (cured) at 140–180°C; not melt-reprocessable once cured
Invented
Used since c. 1600 BC by Mesoamerican cultures; vulcanization — which made it commercially durable — invented 1839 by Charles Goodyear, USA
Common Uses
Tires, footwear, seals, elastic bands
Nitrile Rubber NBR
Resin Code 7Identification
Density 0.98–1.00 g/cm³ (varies with acrylonitrile content); thermoset once vulcanized, no melt point; burns sooty yellow-orange, sharp rubbery odor; sinks / near-neutral in water
Solubility
Resistant to oils, fuels and greases — its defining trait; swells in ketones and esters
Specification
ASTM D2000 / ASTM D412; Shore A hardness per ASTM D2240
Processing Parameters
Compression/injection molded and vulcanized at 150–190°C; not melt-reprocessable once cured
Invented
1930/1931 — Erich Konrad & Eduard Tschunkur, IG Farben, Germany; commercial production from 1935
Common Uses
Fuel/oil hoses, gaskets, disposable gloves, seals
Silicone Rubber Si
Resin Code 7Identification
Density 1.10–1.60 g/cm³ (filler-dependent); thermoset, no melt point; leaves a white/grey silica ash on burning rather than charring — a distinctive identifier; sinks in water
Solubility
Resistant to most solvents, oils and chemicals; swells slightly in nonpolar hydrocarbons (toluene, hexane)
Specification
ASTM D2000 / ASTM D412; Shore A hardness per ASTM D2240
Processing Parameters
Compression/injection molded and cured at 100–180°C depending on cure system; usable over an unusually wide range, -60°C to 250°C
Invented
1943 — Dow Corning Corporation, USA (building on Frederic Kipping’s organosilicon research, England, early 1900s)
Common Uses
Medical devices, bakeware, seals, cables
Polybutylene Adipate Terephthalate PBAT
Resin Code 7Identification
Density 1.21–1.27 g/cm³; melts 110–120°C; flexible, soft-flame burning with a faint sweet ester odor similar to other polyesters; sinks in water
Solubility
Soluble in chlorinated solvents (chloroform, dichloromethane); resistant to water and dilute acids at room temperature; ester linkages hydrolyze and biodegrade under composting conditions (heat, moisture, microbial activity)
Specification
ASTM D6400 / EN 13432 / IS 17088 (industrial compostability) — density per ASTM D792
Processing Parameters
Melt temp 150–190°C (lower than PET — a flexible aliphatic-aromatic copolyester); drying recommended, <0.04% moisture; mold temp 15–40°C
Invented
1998 — BASF, Germany (commercialized as Ecoflex®, the world’s first certified-compostable polymer)
Common Uses
Compostable bags, agricultural mulch film, flexible packaging (often blended with PLA or starch)
Who we work with
Different points in the polymer supply chain run into different problems — we adjust the diagnosis accordingly.
Processors
Injection molders, extruders and blow molders chasing down defects, scrap rates, or processing-window problems.
Recyclers
PCR and PIR operations working to hit consistent, sellable spec out of a variable feedstock.
Compounders
Custom formulators validating new blends, additive packages, and performance claims before they scale.
Manufacturers
Product companies troubleshooting a material that's failing in the field or falling short of a design spec.
Send us a case
Tell us what's going wrong and what you've tried so far. We'll tell you what testing we'd recommend and what it typically takes to get to a fix.
Speak to our CEOHarshita, Chief Executive Officer — 96257 04010
Where we workDelhi-based, serving clients across India and internationally.
Authorised agentSinghal Plastics represents Polymer Doctor for regional inquiries.
B2420, DSIIDC, Narela, Delhi
singhalplastics1986@gmail.com · 93136 36358
B2420, DSIIDC, Narela, Delhi
singhalplastics1986@gmail.com · 93136 36358