Long fiber thermoplastic (LFT) technology continues to develop. While automotive applications retain their market dominance, other industry areas are increasingly attracted by the promise of light weight and high strength - LFT PP compounds, for example, can offer lower cost alternatives to metals as well as higher cost technical engineered polymers.

Continuous penetration of LFT PP compounds in the automotive sector

According to a report released by AMI Consulting in September 2021, PP market penetration continues to rise. The report quantifies the use of LFT PP in granular form (LDT-G) and direct-in-line composite LFT PP (LDT-D) and tracks usage around the world. LFT PP is widely used in automotive front end mounts, dashboard mounts, door panels, consoles, pedals, underbody shields and many other automotive applications, the company said. One feature of these applications is that LFT PP is replacing steel - thereby reducing weight - or more expensive engineering plastics.

AMI Consulting forecasts that LFT PP will maintain strong growth through 2025. Although growth rates vary across application segments, automotive Oems, and geographic markets. In the past, Europe was the leader in LFT sales, but that has changed. Asia accounts for 50% of global LFT PP demand in 2020, compared with 26% in Europe and 24% in the Americas (Table 1), according to the report.

Table 1: Global LFT PP market distribution in the past 20 years

One of the fastest growing application areas is lift doors for car trunks, which range in design from all metal to almost no metal. In metal-free designs, LFT PP is used to provide structural strength and is complemented by high performance PP to provide a paintable exterior skin. In the most demanding applications, the LFT PP elements within the structure are exposed and therefore require a good aesthetic finish. Plastic lift doors are especially valuable to electric car makers as a new way to reduce weight.

The shift to electric and hybrid vehicles, while threatening some existing polymer applications, is also creating new opportunities for LFT PP as designers are rethinking concepts and adopting new approaches. The report cites the example of Tesla's "frunk" -- a back-up or storage compartment located at the front. This would make use of space in the front of the vehicle for storage, but would need to be designed with the ability of a traditional car's front end to absorb the impact of a crash.

The strong interest in LFT materials from various industries is confirmed by RTP Inc., which offers a wide range of LFT materials. "Replacement metal parts or over-engineered short fiberglass compounds continue to be major growth opportunities," said Zach Halverson, Manager of the company's structured products business. For example, long fiber polypropylene compounds can often successfully replace short glass fiber polyamide compounds to provide a lower cost and lower density solution." Long fiber technology in engineering and high performance based polymers such as PEEK, PPA, PEI and PPS, these combine the desired mechanical and thermal properties of the polymer with the added benefit of long fibre reinforcement. They are said to be a good alternative to metals in particularly demanding environments, such as in the oil and gas industry, where other materials cannot meet demand (Table 2)

Table 2: Long glass fiber reinforced polymer compounds with tensile strength range of 40%.

Halverson said the automotive industry remains the largest consumer of long-fiber thermoplastics, and any changes in the industry will affect its use.
As the primary end user of LFT, the performance needs of the automotive industry are a key driver of LFT development. Current challenges include increasingly stringent VOC limits, the ability to withstand long-term thermal aging of more than 1,000 hours at 150°C (Figure 3), stronger UV-resistant linearity, and the ability to achieve A highly aesthetic Class A surface finish directly outside the mold. Usually several of these requirements need to be met in an application process.

Figure 3: Long-term 1,000-hour thermal aging data of 40% long fiber reinforced PP composites from RTP at various temperatures.

To address these automotive challenges, Xiamen LFT composite plastic Co.,ltd's product development team is constantly experimenting with extensive experimental combinations of new formulations, and developed anti - UV grade products.

Long fibre technology is now a mature area of the thermoplastic market. Nearly 40 years have passed since long fibre reinforced thermoplastics were first introduced in the early 1980s. So the industry is definitely at or reaching a stage of maturity, particularly in commodities for materials such as long glass fibre polypropylene, where it has a large number of suppliers. Most market research reports indicate that the long fiber materials market will continue to grow at a high single-digit CAGR for the foreseeable future. Growth has been prominent in the automotive industry, where long fibre materials are valued for their lightweight capabilities in metal replacement scenarios. The growth in material use has coincided with an increase in the global production of cars and trucks. Transportation is not the only market segment focusing on weight loss. Consumer discretionary products, especially sports and industrial equipment, are moving toward more portable devices that make life easier for users. While lightweight is often the first choice for product designers, the change to metal composites offers many other benefits. Cost reduction is a major driver, easily achieved when switching from metal manufacturing to injection molding production. The metal-like properties of long fiber composites, combined with their excellent durability, can also produce very strong products. These products are also usually made with recycling capabilities in mind. In a world increasingly concerned with the life cycle of materials, this is a necessary consideration.

LFT is valued for its lightweight and strength in applications such as off-road vehicles.