SURFACE-MODIFIED POLYMER PARTICLES: PERFORMANCE

ADDITIVES

2021

INTRODUCTION

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Surface-modified polymer particles are a class of performance additives for polyurethanes, epoxies, andother thermosets that has been growing in commercial use for the last years.

Surface-modification is a process whereby the chemical structure of the surface of an item is changed.“Items” can be anything such as film, reinforcement fibers, molded goods, and even particles. Whilenumerous properties of materials are defined by surface structure, we are concerned with those thataffect compatibility and adhesion. Surface-modification facilitates the incorporation of polymer particlesin epoxies and polyurethanes that normally are incompatible.

Incorporation of surface-modified polymerparticles in polyurethane formulationsactually results in formation of compositematerials. The polymer particles retain theirsize and shape during molding. When cured,the composite material consists of epoxy orpolyurethane, as the continuous phase, andpolymer particles dispersed throughout, asthe discontinuous phase. Such structures areexamples of polymer-polymer composites, asillustrated in Figure I.

POLYMER-POLYMER COMPOSITE STRUCTURE

Figure I

GRAFTABOND Particle (can be virtually any type polymer)

Polyurethane or Epoxy

WETTING & DISPERSION

The oxygen-containing chemical functionalities on surface-modifiedparticles cause high surface energy. This in turn means that the treatedparticles are readily wetted and dispersed in polar media, such as polyols,prepolymer, and even water. The effectiveness of surface-modification onwettability and dispersion is dramatically illustrated by comparing thedispersibility of treated and non-treated ultrahigh molecular weightpolyethylene (UHMWPE) particles in water (Figure II).

Excellent dispersibility is necessary in order for composite materials tohave good physical properties. If polymer particles are not well wettedand dispersed, clumps of dry particles result in the cured material. Theseareas function as voids and result in poor physical properties, which leadto poor performance and premature failure.

Figure II

ENHANCED WETTING AND DISPERSION

Non-treated UHMWPE (left) and surface-modified UHMW PE (right) in water.

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BONDING TO EPOXIES, PU, AND OTHER MATRICES

The surface modification is also very important because it results in much stronger bonding between

the particles (or fibers) and the matrix resin. The enhanced adhesion is a result of chemical bonding

with surface functionalities. The improved bonding of treated particles is illustrated via scanning

electron photomicrographs comparing the failure surfaces of tensile samples made with non-treated or

surface-modified UHMWPE particles in a polyurethane matrix (Figure III). With non-treated UHMWPE

particles, adhesion is so weak that the particles pull away as the sample breaks. In contrast, treated

UHMWPE particles adhere so tenaciously that they tear in half and do not pull out of the polyurethane.

Figure III

ENHANCED BONDING of PARTICLES

Photomicrographs of non-treated (left) and surface-modified (right) UHMW PE particles in a polyurethane matrix clearly illustrate the enhanced bonding of the latter.

USE in EPOXIESWith their polar surfaces, GRAFTABOND™ polyethylene particles are very compatiblewith epoxy resins. Incorporation in epoxy formulations imparts desirable propertyenhancements including increased toughness and greater abrasion resistance. Thisenables formation of end products with outstanding performance.Data illustrating how incorporation of GRAFTABOND™ polyethylene particles in anepoxy increase performance as an adhesive is summarized in Figure IV. In thisexperiment, the shear overlap strengths of three adhesives bonding two pieces of steelwere measured. The adhesive formulations were an unfilled epoxy, and twoformulations incorporating 10% and 30% by weight GRAFTABOND™ UPH-SAN, surface-modified UHMWPE particles. The sample made with 30% GRAFTABOND™ particlesshows a lap shear increase of almost 50%.

Adhesive Lap Shear Strength (psi)

Unfilled epoxy 7,500

10% (wt) GRAFTABOND™UHP-SAN 9,200

30% (wt) GRAFTABOND™UHP-SAN 11,100

EPOXY ADHESIVE STRENGTH

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USE in CAST POLYURETHANE➢ Abrasion Resistance from Surface-Modified UHMWPE/HDPE Particles

➢ Abrasion Resistance from titanium carbide polymer alloy particles

➢ Adhesion to Substrates

➢ Stronger Paint Adhesion

➢ Enhanced Barrier Properties

➢ Reduced Solvent Swell

➢ Tear Resistance and Cut Resistance

➢ Reduced Coefficient of Friction

Surface-modified polymer particles represent a new dimension in material engineering. Incorporation

of these particles in cast polyurethane systems can help molders create unique combinations of

properties desired for specific applications. The chemically-functionalized treated particles enable

new types of performance-functional polyurethanes to be made. This will continue enhancing the

competitive positioning of the industry.

NANOMODIFIED POLYMER POWDERS AND COMPOSITES

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• To increase abrasion resistanse, gloss, toughness, adhesion to metal, glass, concrete etc.Paints and coatings

• Coefficient of friction - increase or decrease abrasion resistanseHeavy duty goods

• Abrasion resistanse, creep resistanse, solvent resistanse, adhesion and compatibilization

Thermoplastic and Thermosets

• Increase abrasion resistanse, coefficient of friction, adhesion Rubber goods

• Abrasion resistance, flexibility, adhesionCast Polyurethane,

Epoxy, Polyether

• To change module - increase or decrease, increase adhesion

Adhesives and Sealants

GP POWDERS

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GRAFTABONDReactive

Monomer

Grafting

Degree

[%]

Form

Olefin/

PA

Blends

Glass

Fiber or

Mineral

Filled

PP

Natural

Fiber Filled

Polyolefins

Metal

Adhesion

Polymer

Film

Adhesion

Non-

Halogen

FR

Mixed

Recyclates

A

B

S

P

A

S

A

N

PVC WPCP

C

Polyesters

(PET,PBT)

UHP-MAH MAH 2,5-3 Powder ● ●

UHP-GMA GMA ~1,5 Powder ● ●

UHP-SAN SAN 4,5-5 Powder ● ●

Graft Polymer offers powders based on UHMWPE with using the most innovative technology method of Solid-

state graft copolymerization. UHMWPE graft copolymers have enhanced thermal stability and excellent nucleating

efficiency & improved rheological properties. Any type of monomer (GMA, MAH, Amine, NCO) can be grafted.

Examples of grafting functionalities are shown below.

GRAFTABOND™ UHP-MAH 0030

Ultra High Molecular Weight Polyethylene grafted

with Maleic Anhydride

Compatibilizer in engineering plastics composites,

compounds and alloys as impact modifier.

Processing

• Processable on most thermoplastic processing

equipment

• Preferable for: Extrusion (Compounding)

Dosage 1-5%

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GRAFTABOND™ UHP-GMA 0050

Ultra High Molecular Weight Polyethylene grafted with Glycidyl

Methacrylate

Impact modifier for engineering polyesters, polyester and epoxy

based thermosets.

Special Features and Benefits

• Improves mechanical properties: stiffness tensile and flexural

properties, impact strength,

Processing

• Material is processable on most thermoplastics processing

equipment.

• Preferable processing method: Extrusion (Compounding).

*Supplied as: Granulate also as a Powder in a special request

Dosage 1-5%

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GRAFTABOND™ UHP-SAN 0050

Ultra High Molecular Weight Polyethylene, grafted with

Styrene Acrylonitrile

Provides enhanced impact strength to the base

material, while also maintaining compatibility with

polymers that contain nitrile and amide groups.

Applications

• Is a great additive for increasing impact strength of

soft materials;

• Provides excellent compatibility with polymers,

containing nitrile or amide groups (e.g. SAN, ABS),

Dosage 1-5%

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WHAT MAKES GP UNIQUE

Use proprietary co-agents and redox initiating system for grafting

Use of Nitroxide Mediated Polymerization for controlled grafting reactions

Co-continuous nano-morphology approach for creation polymeric alloys

Interpenetrating Polymer Networks (IPN)

Thermo-Reversible Crosslinking polymers and Vitrimers

Smart Polymers Self-Healing polymers

In-house synthesis of unique “nitroxide stable radicals” (TEMPO) for high-tech composite materials – proprietary process

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BUSINESS MODEL: INNOVATIONS

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S Y N T H E S I STo support its unique modification technologies, GP has built the R&D center including Laboratory and Synthesis facilities

G R A F T / B L O C K P O L Y M E R S

P O L Y M E R I C N A N O A L L O Y S

C R O S S L I N K I N G

P O R O U S

• Flow induced crystallization

• Solid Phase Grafting

• Solution Grafting

• Fillers Treatments

• Powders Hybridization

• Hot ozonolysis/plasma modification

• Nitroxide Mediated Polymerization

• Micro/Nano Porous polymer carries

INNOVATIVE TECHNOLOGIES

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Contact information

Info(at)graftpolymer.com

www.graftpolymer.com

Anjeza Kuhar | Sales ManagerEnglish / Italian / AlbanianPhone: +386 40 380 668anjeza.kuhar(at)graftpolymer.com

Ekaterina Kulevskaia | Sales ManagerEnglish / Russian / SlovenianPhone: :+386 31 399 366ekaterina(at)graftpolymer.com

Pavel Kobzev | English / HebrewBusiness Development & Sales Director Phone: +386 40 867 937Pavel(at)graftpolymer.com