Continuous fiber reinforced thermoplastic composite, as its name implied, is a combination of fiber reinforcement and resin matrix (often thermoplastic resin). Here let’s see some of the ingredients most used in the two parts of CFRT material.

 

Fiber Reinforcement

There are many different types of fibers that can be used to reinforce polymer matrix composites. The most common reinforcements are carbon fiber and glass fiber. You can choose different fiber materials according to your final application.

▼Natural fiber (hemp, linen, cotton yarn, etc.)

  • Low cost, low density(~1.5 g/cm3), lightweight, green
  • Higher fiber content than glass fiber
  • High end of life biodegradability

Since the 1990s, natural fiber composites are emerging in many applications. They are particularly attractive in automotive applications because of lower cost and lower density. Natural fibers, especially polypropylene composites, have attracted greater attention due to their added advantage of recyclability.

 

▼Glass fiber

  • Cheaper and more flexible than carbon fiber
  • Higher elongation at break compared to carbon fiber
  • Moisture resistance
  • Chemical resistance to acids and solvents
  • Low dielectric constant
  • Electric insulation
  • Thermal conductivity

Glass fiber production requires 5–10 times more non-renewable energy than natural fiber production.

It has better mechanical properties than natural fiber, but not that strong as carbon fiber. The issue of low stiffness can be easily overcome by designing sandwich structures where a lightweight core can be sandwiched between two glass skins and thereby making the end result stiffer.

There are various grades available in glass fiber, among which E grade is most commonly used, while R and S grades perform better in mechanical properties and also more expensive.

 

▼Carbon fiber

  • Lightweight and high stiffness:
  • About 1/4 space gravity compared with iron about 2/3 of aluminum;
  • Stiffness and strength higher than iron
  • High thermal conductivity
  • Low coefficient of thermal expansion
  • Outstanding wear resistance

Carbon fiber reinforced thermoplastic composites have received much attention because of their easy processability and recycling convenience compared with thermosetting composites.

Application: Aerospace, construction, and civil engineering, sports, automotive components

 

▼Basalt fiber

  • Long fatigue life
  • Lower cost than carbon fiber
  • Better physicomechanical property than glass fiber

Made from extremely fine fibers of basalt, basalt fiber performs better than glass fiber in physicomechanical properties. It’s suitable for aerospace and automotive components and has become an emerging cost-effective replacement for traditional glass and carbon fibers.

 

▼HMW PE fiber with high strength and modulus (HMW=high molecule weight)

  • Strong acid resistance
  • Abrasion resistance
  • Low moisture absorption

HMW  is also called UHMWPE(Ultra-high-molecular-weight polyethylene) or HMPE(high-modulus polyethylene). The HWM PE is strongest in impact resistance of extant thermoplastics.

 

▼Aramid fiber

  • High strength, high elastic modulus, and high abrasion resistance
  • Strong heat resistance
  • Outstanding strength-to-weight property
  • High chord modulus
  • High tenacity
  • Low creep
  • Low elongation at break (~3.5%)
  • Difficult to dye (usually solution-dyed)

Aramid is a synthetic fiber made from the polymer aromatic polyamide. It’s mainly divided into two meta-aramid and para-aramid according to the different location of chemical bonds. Para-aramid performs better in tensile strength.

 

Resins

Thermoplastic:

The thermoplastic resin is a polymer compound that becomes soft or fluid when heated and then returns to its original solid state when cooled. It’s commonly used in injection molding. Products of thermoplastic resins are strong in chemical resistance. Most of them have a hard, crystalline or rubbery surface.

▼PE (polyethylene)

  • High impact strength
  • High ductility and low friction
  • Low hardness and rigidity
  • Electrical treeing resistance
  • Softer and tougher than most commodity resins

▼PP (polypropylene)

  • Higher stiffness and strength than PE resin
  • Lower toughness in cold conditions
  • Excellent tensile and impact strength

 

▼PVC (polyvinyl chloride)

  • A high level of chemical resistance
  • Water and abrasion resistance
  • Ultraviolet exposure should be avoided

PVC is the world’s third most widely used plastic for its versatility, durability and cost competitiveness. It’s especially needed in the building process, whose purpose is for lightweight, long-lasting and maintenance-free.

 

▼PPS (polyphenylene sulfite)

  • Heat resistance
  • Chemical resistance
  • Excellent dimensional stability
  • Low moisture absorption
  • Recyclability

PPS is an engineering plastic commonly used as a high-performance thermoplastic.

 

▼PEEK (Poly-ether-ether-ketone)

  • High chemical resistance
  • High hardness, stiffness, and strength
  • Excellent fatigue and stress-crack resistance

Similar to PPS fiber, PEEK is also semicrystalline thermoplastic with excellent mechanical and chemical resistance. It is an advanced new material that provides more toughness, meanwhile, it’s also more expensive and difficult to process.

 

▼PC-polycarbonate (plastic/resin)

  • Superior transparency and self-extinguishing properties
  • High impact resistance but low scratch resistance

Unlike most thermoplastics, polycarbonate can undergo large plastic deformations without cracking or breaking. It is often used in automotive interiors and exteriors.

 

▼ABS (Acrylonitrile Butadiene Styrene)

  • Medium strength
  • Heat resistance, impact resistance and toughness
  • Great Electrical Insulation Properties
  • Easy to be machined, sanded, glued and painted, great material for prototyping
  • Poor weatherability
  • Poor solvent resistance
  • High smoke generation when burned
  • Comparatively high cost

Since ABS is combined with 3 kinds of monomers, its quality and final properties are greatly depended on the processing method and the proportion of these components.

 

▼PA (polyamide, nylon)

  • High strength
  • Dimensional stability
  • Wear resistance

The polyamide resin is usually for auto parts, sports goods, and machinery parts.

 

Thermosetting:

Thermosetting plastics are generally stronger than thermoplastic materials due to the three-dimensional network of bonds (cross-linking) and are also better suited to high-temperature applications. In addition, thermosetting resins cost less than thermoplastics.

▼Polyester (PET/PBT)

  • Low cost, low viscosity, and a relatively short curing period
  • Adequate resistance to water and a variety of chemicals
  • Good wetting to glass fibers
  • Lower mechanical properties than other thermosets
  • Strong styrene odor

Polyester resins are the most widely used resins, particularly in the maritime and automotive industries.

 

▼TPU (thermoplastic polyurethane)

  • Excellent mechanical properties and toughness
  • Superior abrasion resistance
  • Good chemical, oil and solvent resistance

 

▼Epoxy (polyepoxides)

  • Stronger and more recyclable than usual resins

Epoxy resin has a wide range of applications, including metal coatings, high tension electrical insulators, fiber-reinforced plastic materials, and structural adhesives.

There are many grades in epoxy resin, such as Bisphenol F epoxy resin, Bisphenol A epoxy resin, Novolac epoxy resin, cycloaliphatic epoxy resin, etc..

 

▼PETG (polyethylene terephthalate glycol)

  • Excellent thermosetting performance
  • High toughness (15-20 times higher than that of PMMA)
  • High weather fastness
  • Easy to process
  • Chemical resistance
  • Less cost than PC resin
  • Recyclability