Synthetic Fibers for Knitwear: Acrylic, Nylon, Polyester (OEM/ODM Technical Guide)

Overview of Synthetic Yarn Families in Knitwear

Synthetic fibers used in knitwear come primarily from three categories:

• Acrylic (PAN fiber)

• Nylon (Polyamide)

• Polyester (PET)

Each serves a different function and behaves differently during knitting, washing, and wearing.

Why Synthetic Yarns Are Popular for Knitwear

Key advantages include:

• Excellent colorfastness

• Minimal shrinkage

• High abrasion resistance

• Stable price and supply

• Predictable bulk performance

• Versatility across gauges (3GG–16GG)

• Suitable for high-volume programs

Compared with natural fibers, synthetics provide higher yield, lower risk, and smoother production, making them ideal for fast fashion and commercial retailers.

Acrylic Yarn (The Most Common Synthetic for Knitwear)

Acrylic is widely used in sweaters, scarves, beanies, and winter accessories due to its wool-like appearance and soft hand-feel.

Fiber Characteristics

Acrylic fibers are engineered to mimic wool.

• Lightweight

• Soft and warm

• Wool-like loft

• Good bulkiness

• Colorfast and durable

Acrylic retains heat well and resists moisture absorption, making it ideal for winter knitwear.

Production Behavior in OEM Factories

Acrylic yarns are generally easy to knit.

Benefits:

• Stable machine tension

• Low breakage rate

• Suitable for multi-color jacquards

• Works across gauges: 3GG–14GG

• Ideal for textured stitches like cables and ribs

Factory note: Acrylic tends to pill more easily than nylon or polyester unless treated with anti-pilling technology.

Types of Acrylic Used in Knitwear

Standard Acrylic

• Most affordable

• Soft and bulky

• Good for basic sweaters

Anti-Pilling Acrylic

• Improved surface strength

• Suitable for children’s wear and high-wear products

Acrylic/Wool Blends

• Combine warmth of wool with durability of acrylic

• Reduce cost while maintaining premium aesthetics

Acrylic/Cotton Blends

• Used for spring/summer sweaters

Acrylic/Polyester Blends

• High durability

• Strong colorfastness

Best Applications

• Winter sweaters

• Chunky 3GG–5GG knits

• Jacquard pullovers

• Beanies and scarves

• Youth and streetwear

Acrylic is often chosen for commercial brands requiring wool-like results without premium wool prices.

Nylon (Polyamide) Yarn in Knitwear Production

Nylon is known for its strength, elasticity, and resistance to abrasion. It is often used as a support fiber in blended yarns.

Fiber Characteristics

• High tensile strength

• Excellent stretch

• Superior durability

• Low pilling

• Smooth surface

Nylon is one of the strongest synthetic fibers available.

Behavior in Knitting Production

Nylon’s high elasticity allows factories to create stable, smooth fabrics.

Factory advantages:

• Panels maintain shape

• Less risk of needle breakage

• Better recovery for ribs and cuffs

• Perfect for engineered fit garments

Types of Nylon Yarn

Fully Drawn Nylon (FDY)

• Smooth surface

• High strength

• Good for fine gauge

Nylon/Spandex Blends

• Offers stretch for body-hugging styles

• Common in women’s tops and sportswear

Nylon/Wool Blends

• Used to reinforce wool or cashmere

• Increases durability

• Reduces pilling

Best Applications

• Fine-gauge sweaters

• Sportswear knit tops

• Body-fit knits

• Structured ribs

• High-recovery cuffs and collars

• Durable winter accessories

Nylon is essential for brands seeking longevity and shape retention.

Polyester Yarn in Knitwear Manufacturing

Polyester is one of the world’s most widely used fibers due to its strength, stability, and cost efficiency.

Fiber Characteristics

• Excellent durability

• Minimal shrinkage

• High colorfastness

• Low-moisture absorption

• Resistant to wrinkles

Compared with acrylic, polyester offers better long-term durability but slightly less softness.

Production Performance in OEM Factories

Polyester is extremely stable during knitting:

• Low breakage rate

• Fast knitting speed

• Perfect for jacquard structures

• Very smooth stitch appearance

Polyester also performs strongly in post-processing:

• Shrinkage is predictable

• Colorfastness is high

• Pilling is significantly lower

Types of Polyester Used in Knitwear

Filament Polyester

• Smooth

• Shiny

• Ideal for fashion tops

Spun Polyester

• Matte

• Cotton-like surface

• Used for sweaters

Recycled Polyester (rPET)

• Made from recycled plastic bottles

• Highly demanded by sustainable brands

• Used in eco-friendly knit programs

Best Applications

• Mass-market sweaters

• POLO knits

• Corporate uniform knitwear

• Schoolwear and workwear

• Performance knitwear with moisture-wicking finishes

Gauge Selection and Stitch Behavior (3GG–16GG)

Synthetic yarns work well across a wide gauge range.

3GG–5GG

• Chunky sweaters

• Cable knits

• Winter accessories

Acrylic is especially suitable due to its wool-like bulk.

7GG–10GG

• Transitional sweaters

• Cardigans

• Structured fashion knits

Blended synthetic yarns help maintain measurement stability.

12GG–16GG

• Fine-gauge basics

• Uniform knitwear

• Sportswear knits

Nylon and polyester are most stable in fine gauge production.

Production Issues and Factory Controls

While synthetic fibers are easier than natural fibers, some issues still require technical control.

Pilling

Synthetic fibers can pill if the filament is short or has rough surface texture.

Factory solutions:

• Use anti-pilling acrylic

• Increase twist level

• Conduct pilling tests (ISO 12945)

• Apply anti-pilling finishing

Static Electricity

Acrylic and polyester can hold static charge.

Solutions:

• Add fabric softener

• Use anti-static spray during finishing

• Maintain humidity in workshop

Heat Sensitivity

Synthetic fibers melt or deform under high temperatures.

Factory management:

• Control ironing temperature strictly

• Avoid excessive steaming

• Use low-temperature dyeing processes

Dye Lot Variation

Dyeing is stable, but cheap yarns may still cause shade inconsistencies.

Factories must:

• Source from stable suppliers

• Keep lot numbers consistent

• Conduct pre-production color tests

Applications for Global OEM/ODM Brands

Different synthetic fibers serve different brand categories.

Acrylic → Best for Winter Fashion

• Chunky knits

• Cable sweaters

• Streetwear pullovers

• Budget-friendly knitwear

Nylon → Best for Technical and Durable Knitwear

• Sportswear

• Ribbed tops

• Fine-gauge basics

• Workwear requiring strength

Polyester → Best for Commercial, Uniform, and High-Durability Programs

• Corporate knitwear

• School uniform sweaters

• Polo knits

• Recycled polyester eco-programs

OEM/ODM Workflow for Synthetic Fiber Knitwear

Yarn Sourcing

Factories purchase synthetic yarns from:

• Hengli

• Tongkun

• Xinfang

• Sinopec

• Various rPET recyclers

Sample Development

• Initial tension test

• Panel knitting across target gauges

• Test washing

• Pilling test

• Hand-feel comparison

Lead time: 2–4 days.

Bulk Production

• Smooth knitting process

• Highly stable tension

• Minimal waste

• Faster output compared to wool/cotton

Finishing & QC

Finishing includes:

• Steaming

• Softening treatment

• Anti-static treatment

• Anti-pilling finishing

QC tests:

• Colorfastness

• Pilling resistance

• Measurement stability

• Shrinkage verification

• Panel consistency