POLYMER DOCTOR Polymer Diagnostics & Research Center
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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.

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Testing · Diagnosis · Formulation · Process support

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 / Improve

Recover performance

Address MFI drift, lost strength, processing issues and inconsistent recycled streams with a workable formulation or process change.

See our expertise → 03 / Add

Choose 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.

Recycling & recoveryRestore useful properties and improve consistency. MFI modificationAdjust flow for the intended process and product. Performance additivesCoupling, flame retardancy, silicone and foaming systems. Testing & failure analysisUnderstand why parts or batches miss a target.
Illustration of a woven sack extrusion coating and lamination line
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 case

Products

Our existing additive range, with the new lamination adhesion additive added below.

Existing additive range

Coupling Agents

We make coupling agents by grafting maleic anhydride (MAH) or glycidyl methacrylate (GMA) onto different polymer bases selected for the resin and application. The selected backbone is compatible with the base polymer, while the grafted anhydride or epoxy groups can interact with, or react with, suitable polar fillers, fibres and other polymer phases. This helps improve dispersion and adhesion at the interface. We select the polymer base and graft chemistry to suit each requirement and confirm performance in a processing trial.

Illustration of a running twin-screw polymer compounding line
Illustrative twin-screw compounding line
Illustration of strands cooling and pelletizing on a twin-screw compounding line
Illustrative strand cooling and pelletizing

Flame Retardants

Many polymers can ignite and continue to burn when exposed to a flame. Flame retardants are added to reduce fire growth and help a finished formulation meet the fire-performance requirement for its intended use. The result depends on the polymer, loading, processing and finished-part or film thickness.

How do they work?

Different chemistries act in different ways. Some interrupt flame reactions in the gas phase. Others encourage a protective char or barrier on the polymer surface, reducing the heat and fuel reaching the flame. A formulation may use more than one mechanism.

Our range

We provide both halogenated and non-halogenated flame-retardant systems. We also develop flame-retardant options for transparent film applications, where clarity, haze, film thickness and the relevant fire test must be considered together.

Halogenated: selected where the polymer, processing conditions and target performance suit the system.Non-halogenated: options selected for the required polymer, application and performance.Transparent films: formulations chosen with optical appearance and thin-film testing in mind.
Fire response, step by step
Heat causes a polymer to release combustible vapours.
The selected additive acts in the flame, at the surface, or both.
Less heat or fuel feeds the flame; the tested formulation may self-extinguish.
What do V-0, V-1 and V-2 mean?

These are UL 94 vertical-burning classifications for a tested material formulation and specimen thickness. They describe afterflame time and whether flaming drips ignite cotton below the specimen.

UL 94 ratingMaximum afterflame time, each applicationFlaming drips that ignite cotton
V-010 secondsNot permitted
V-130 secondsNot permitted
V-230 secondsPermitted

A rating belongs to the tested formulation at the reported thickness; adding a flame retardant alone does not confer a V-0, V-1 or V-2 rating. Very thin films may need UL 94 VTM testing, whose VTM ratings are not equivalent to the corresponding V ratings. See UL Solutions' explanation of the test methods and criteria.

Watch UL 94 testing

UL Solutions' flammability webinar shows test-method animations for HB and the vertical V-0, V-1 and V-2 classifications. For the other UL 94 categories, including 5VA/5VB, thin-film VTM and foam ratings, use the accompanying test-method guide. Different test families have different procedures and their ratings are not directly interchangeable.

Watch testing videoExplore all UL 94 test categories ↗

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.

PP MFI Enhancer

Our polypropylene melt flow index (MFI) enhancer helps raise and tune the flow of virgin or recycled PP for the intended process. In a controlled compounding trial, improved flow can help processors convert lower-flow PP into grades more suitable for injection moulding, masterbatch production and selected extrusion applications. The final MFI depends on the starting resin, additive level and processing conditions.

Uses
  • Adjust recycled PP flow for thin-wall containers, buckets, plastic chairs and other moulded articles.
  • Prepare PP blends for colour or filler masterbatch production.
  • Evaluate recycled PP for nonwoven fabric and rope production, subject to strength and process trials.
  • Upgrade suitable film and raffia recyclate for injection moulding applications.
Application-led range

We select the enhancer grade and loading to suit the starting PP and the target MFI: moderate flow adjustment for larger mouldings; higher flow for thin-wall mouldings and masterbatch; and tailored trials for nonwoven, rope or recycled streams. A 1% addition is a trial starting point, not a guaranteed dosage or MFI increase. We check MFI and the finished product's mechanical performance before fixing a production formulation.

Illustrative PP thin-wall containers with translucent lids, bucket and plastic chair
Injection mouldingThin-wall packs, buckets and plastic chairs.
Illustrative PP nonwoven rolls and rope coils at a manufacturing plant
Nonwoven & ropeRecycled PP blends evaluated for fabric and rope lines.
Illustrative recycled PP film and raffia with a compounding line and masterbatch pellets
Recycling & masterbatchFilm and raffia recyclate, compounding and PP masterbatch.

Illustrative application images. Suitability and target MFI must be confirmed with the actual PP grade, processing conditions and end-use tests.

PP MFI Reducer / Impact Modifier

Some polypropylene grades, especially recycled PP, flow too readily or lack the toughness needed for a demanding product. We formulate PP modification systems to target lower melt flow index (MFI), improved melt strength and/or better impact resistance. The MFI reducer and impact modifier are selected for the particular resin and performance target; one additive should not be assumed to improve every property at once.

Uses
  • Adjust high-MFI recycled PP to a lower-flow processing window.
  • Improve toughness in crates, storage boxes and other durable mouldings.
  • Develop PP compounds for automotive components and industrial housings where impact performance matters.
  • Balance impact strength, stiffness and flow in filled or recycled PP blends.
How we select the formulation

We start with the base PP grade, its measured MFI and the required finished-part performance. The reducer is trialled for the target flow and melt strength; a compatible impact modifier can be selected where added toughness is needed. We then test MFI, impact strength and stiffness at the proposed loading and processing conditions. The suitable grade and dosage are determined by these trials.

Illustrative polypropylene crates and large storage bins
Crates & storageTough, reusable moulded containers.
Illustrative polypropylene automotive exterior and industrial casing components
Automotive & industrialComponents developed for the required impact and stiffness.
Illustrative recycled polypropylene compounding line
Recycled PP compoundsAdjusting flow and toughness in recycled blends.

Illustrative application images. Final properties depend on the polymer formulation, additive loading, processing and part design; verify performance in the finished application.

HDPE MFI Reducer

A performance additive for HDPE formulations where the incoming material has more melt flow than the process needs. Our MFI reducer is designed to lower the measured melt flow index and improve melt strength in a suitable HDPE blend. This can help processors evaluate recycled or off-specification streams for more stable extrusion or blow moulding, subject to the finished product's required tests.

Uses and applications
  • HDPE pipe extrusion: target a more suitable flow and melt strength for stable processing and wall-thickness control.
  • Drums and containers: evaluate recycled HDPE for blow-moulded drums, jerrycans and industrial containers.
  • Recycled HDPE compounds: tune variable feedstock toward a specified processing window before production.
Starting a trial

The supplied product reference proposes 1% addition as a starting trial dosage. We measure the feedstock MFI, compound a trial batch and check the resulting MFI and melt behaviour. Pipe applications also require the appropriate pressure, slow-crack-growth and other qualification tests; a lower MFI by itself does not establish a PE100 rating or suitability for pressure service.

Illustrative HDPE pipe extrusion and cooling line
HDPE pipe extrusionFlow adjustment and stable extrusion trials for pipe compounds.
Illustrative HDPE drums, jerrycans and recycled HDPE material
Drums & recycled HDPEBlow-moulding and recycled material evaluation.

Illustrative application images. The final grade, dosage and end-use performance must be verified on the actual HDPE feedstock and production line.

LDPE Modifier

Designed for LDPE and suitable recycled film blends, our modifier targets recovery of melt strength and film performance. Its reactive action can help rebuild effective chain structure in a compatible formulation, reducing melt flow index (MFI) while increasing melt strength. The response depends on the feedstock, its degradation history and the processing conditions.

What happens as MFI reduces?
  • Stronger melt: within a suitable processing range, the melt resists stretching and sagging better, helping the blown-film bubble hold its shape.
  • More stable film: steadier bubble behaviour can reduce gauge fluctuations and breaks, supporting consistent production.
  • Strength recovery: evaluate tensile, elongation, tear and puncture performance in films made with recycled LDPE; lower MFI alone does not prove these gains.
Filler loading & production

Improved melt strength may let a processor trial higher filler loading while keeping the bubble stable. A steadier run can also create room to increase output. The workable filler percentage and line speed depend on filler size and dispersion, the LDPE blend, film thickness, die, cooling and end-use requirements. Too low an MFI may raise melt pressure and make extrusion harder, so we tune the modifier and filler together and test film strength, appearance and gauge before setting production conditions.

Illustration of a running LDPE blown-film line with an inflated film bubble
Blown-film bubbleExtrusion, inflation and controlled bubble formation.
Illustration of a blown-film plant with bubble, guide rollers and finished film winding
Film windingFilm travel through rollers to the winding station.

Confirm the formulation on the actual LDPE blend and blown-film line. A lower MFI alone does not prove recovered mechanical strength; test the finished film.

Nylon Impact Modifier / MFI Reducer

During high-temperature processing and repeated recycling, nylon chains can undergo scission, especially when the material is not adequately dried. Shorter chains can raise melt flow and reduce the strength or toughness needed in the finished part. Our nylon modification approach is designed to rebuild effective chain structure in a compatible grade, control excessive MFI and improve impact performance. We select the chain-repair and toughening chemistry for the nylon type and intended process.

Where it helps
  • Nylon recycling: evaluate degraded PA6 or PA66 streams for improved processability and retained value.
  • Rod and profile extrusion: target a suitable melt viscosity and strength for stable extrusion and solid sections.
  • Injection moulding: tune recycled nylon compounds for the required balance of flow and impact resistance.
What we verify

Reactive chain extension can increase melt viscosity and reduce MFI where chain scission has made nylon too fluid. A selected impact modifier may improve toughness, but the same formulation must still flow adequately through the die or mould. We dry the nylon correctly, then compare MFI or viscosity, impact strength and other end-use properties before and after modification. The dosage and outcome depend on PA grade, moisture, reprocessing history and fillers.

Illustrative nylon recycling and twin-screw compounding plant with regrind and strands
Nylon recyclingRegrind, reactive compounding and strand pelletising.
Illustrative nylon rod extrusion plant with cooling line and finished rods
Nylon rod manufacturingExtrusion and cooling of solid nylon rods.

Illustrative plant images. Nylon must be dried and processed to the grade's requirements; verify final mechanical properties and dimensions in production trials.

New addition · Extrusion coating & lamination

Lamination Adhesion Additive PDRC MB399AD

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.

Enquire about MB399ADDownload technical data sheet (PDF)
Illustration of a single-side extrusion coating and lamination line for woven sack fabric
Illustrative view of a woven sack extrusion coating line.

MB399AD typical properties

Values are taken from the supplied PDRC technical data sheet. Use the full PDF for test methods, handling and safety information.

PropertyTest methodTypical value
Melt index (190°C / 2.16 kg)ISO 11336 g/10 min
Melting pointISO 11357-3 / ASTM D341885°C
Vicat softening temperature (10 N)ISO 306 / ASTM D1525<40°C
Flexural modulusISO 178<30 MPa
Elongation at breakISO 527-2 / ASTM D6381100%
Tensile strength at breakISO 527-2 / ASTM D6384 MPa
Processing caution from the TDSMB399 reacts with polymers containing maleic anhydride and acid. Uncontrolled reaction may generate gels or block an extruder. Thoroughly purge the extruder before and after processing.

Store dry and away from moisture. Caking may occur in warm weather due to the low Vicat temperature. The stated shelf life is three years from delivery in unopened packaging; consult the full TDS for details.

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.

First Step
Polymer Identification
Illustrative ftir instrument for polymer identification
Illustrative equipment: FTIR instrument for polymer identification
FTIR spectroscopy (resin fingerprinting)What: Infrared absorption reveals chemical bonds and helps identify the polymer family, including isolated foreign particles.
Why: It flags wrong resins or contamination before processing.
How: Place a cleaned sample on the ATR crystal and compare its spectrum with reference polymers.
Controlled burn-test triageWhat: Rapid observations narrow the likely polymer family.
Why: They guide which instrument test to run next.
How: Observe a small sample under controlled flame conditions where appropriate, then confirm its identity with instrumental analysis.
Flow & Processing
MFI Testing & Rheology
Illustrative melt flow tester used to assess polymer flow
Illustrative equipment: Melt flow tester used to assess polymer flow
Melt flow index (MFI/MVR)What: MFI is the mass of polymer flowing through a standard die in 10 minutes; MVR reports volume.
Why: It helps compare incoming batches and select a process window, but does not alone prove strength.
How: Dry when required, heat the sample at the specified temperature, apply the specified load, then weigh timed extrudate or track piston travel. Always report temperature and load.
Capillary & rotational rheometryWhat: Viscosity is measured over a range of shear rates.
Why: It shows flow closer to extrusion or injection conditions than a single MFI value.
How: Push melt through a capillary die or shear it between rotating plates at controlled temperatures.
Heat & Stability
Thermal
Illustrative dsc and tga thermal analyzers
Illustrative equipment: DSC and TGA thermal analyzers
DSC — melting, crystallinityWhat: Heat flow reveals melting, crystallization and glass-transition behaviour.
Why: It helps assess resin identity, processing history and crystallinity.
How: Heat and cool a small sample alongside a reference pan in a DSC.
TGA — degradation, filler contentWhat: Mass loss versus temperature shows volatilization and thermal decomposition.
Why: It helps estimate residue, filler and thermal stability.
How: Heat a weighed sample under a defined gas atmosphere and record its mass change.
HDT & Vicat softening pointWhat: These indicate softening under a defined load or penetration condition.
Why: They help select materials for elevated-temperature use.
How: Heat a loaded test specimen in a controlled bath and record the specified deflection or needle penetration.
Strength & Durability
Mechanical
Illustrative tensile and impact testing equipment
Illustrative equipment: Tensile and impact testing equipment
Tensile & flexural strengthWhat: Force and deformation show strength, stiffness and elongation.
Why: They show whether parts can carry expected loads.
How: Pull standard specimens in a universal tester or bend them in a three-point fixture.
Impact resistance (Izod/Charpy)What: A notched or unnotched specimen absorbs energy from a pendulum strike.
Why: It indicates resistance to sudden blows and brittle failure.
How: Condition standard specimens, strike them in the specified Izod or Charpy fixture and record energy.
Hardness (Shore A / Shore D)What: Indentation resistance is reported on the relevant Shore scale.
Why: It helps check softness or rigidity of elastomers and plastics.
How: Press the appropriate durometer onto a conditioned specimen at the specified contact time.
Fatigue & long-term stressWhat: Repeated or sustained loads reveal time-dependent damage.
Why: They help assess durability beyond a quick strength test.
How: Cycle or hold a specimen under specified load and environment, then track deformation or failure.
Chemistry & Purity
Compositional
Illustrative furnace and balance for ash analysis
Illustrative equipment: Furnace and balance for ash analysis
Contaminant & foreign-material screeningWhat: Unknown particles or mixed resins are identified.
Why: It helps explain weak spots, streaks or rejected batches.
How: Inspect samples, isolate defects and use microscopy, FTIR or other targeted analysis.
Ash & filler contentWhat: The inorganic residue remaining after controlled heating is measured.
Why: It estimates mineral filler or pigment loading.
How: Weigh the specimen, heat it in a muffle furnace and weigh the residue.
Additive & polymer blend ratiosWhat: The approximate formulation balance is investigated.
Why: It helps compare supplied material with a target composition.
How: Combine suitable methods such as FTIR, DSC, TGA and extraction; method choice depends on the ingredients.
Appearance
Color & Optical
Illustrative color, haze and gloss measurement equipment
Illustrative equipment: Color, haze and gloss measurement equipment
Color measurement (L*a*b*)What: Instrumental color values quantify lightness and color differences.
Why: It makes batch matching more objective.
How: Read conditioned plaques or film against a standard with a calibrated spectrophotometer.
Haze & clarityWhat: Light scattering and transmission describe film transparency.
Why: They matter for packaging appearance and optical quality.
How: Measure a flat film specimen in a calibrated haze meter.
GlossWhat: Reflected light at a specified angle describes surface shine.
Why: It helps control visible finish across batches.
How: Use a calibrated gloss meter on a smooth, representative surface.
Root Cause
Failure Analysis
Illustrative microscopes for examining failed parts
Illustrative equipment: Microscopes for examining failed parts
Microscopy & fractographyWhat: Magnified surfaces reveal cracks, voids and break patterns.
Why: They help locate the origin of a failure.
How: Examine a clean fracture and compare it with an unaffected region under suitable magnification.
Field-vs-spec comparison testingWhat: A failed field sample is compared with an approved control.
Why: It separates material variation from processing or service effects.
How: Test matched specimens using relevant flow, thermal, mechanical and composition methods.
Bulk Properties
Physical Properties
Illustrative balance and sieve equipment for granules
Illustrative equipment: Balance and sieve equipment for granules
Density & specific gravityWhat: Density is mass per unit volume; specific gravity compares it with water density at the stated temperature.
Why: These help check resin identity and filler consistency.
How: Weigh a conditioned sample in air and in a suitable liquid, or use a density-gradient method.
Bulk densityWhat: Loose granules are weighed in a known volume.
Why: It affects hopper feeding and packaging.
How: Fill a calibrated container without compacting, level it and divide mass by volume.
Mesh size / granule uniformity in reprocessed danaWhat: Particle size distribution and pellet consistency are checked.
Why: They influence feeding, melting and filtration.
How: Sieve a representative sample and inspect oversize, fines and shape variation.
Compostability
Bio-compostable Testing
Illustrative controlled composting test equipment
Illustrative equipment: Controlled composting test equipment
Biodegradability (IS 17088 / ASTM D6400)What: Controlled composting measures conversion of organic carbon to carbon dioxide.
Why: It is part of demonstrating compostability, not a visual guess.
How: Run a prescribed aerobic composting test through an appropriately qualified laboratory and compare with controls.
Disintegration under composting conditionsWhat: Physical breakup of specimens in compost is assessed.
Why: It checks whether fragments remain after a defined composting period.
How: Expose specimens under controlled composting conditions and sieve residual material.
Residue & ecotoxicity screeningWhat: Remaining material and compost effects are examined.
Why: It helps establish that compost quality is not adversely affected.
How: Analyze residue and use specified plant-growth or other ecotoxicity tests with controls.
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
Book via WhatsApp — 96257 04010

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 4
Identification
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 2
Identification
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 5
Identification
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 3
Identification
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 6
Identification
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 1
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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 7
Identification
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
Emailpdrc.doctor@gmail.com
polymerdoctors@gmail.com
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
We'll follow up with a testing plan and estimate.