Interview with Dr Rajkiran Tiwari, YTC America
“Bamboo injection-moulding scrap can be reused up to five times”
Dr Rajkiran Tiwari has been with YTC America since 2020 and currently works as R&D Manager. The polymer researcher specialises in thermoplastics, elastomers, polymer blends and composites, with a focus on processing, characterisation and structure-property relationships.
Rajkiran Tiwari
After another summer of heat records, the reminder is hard to miss: the wire harness industry needs to reduce its CO2 emissions. Dr Rajkiran Tiwari of YTC America explains where PP/bamboo eco-composites can replace conventional PP materials and what limits remain.
Reducing the carbon footprint of wire-harness components also means looking more closely at the polymer materials used in their production. One approach is to replace conventional PP/talc compounds with composites containing plant-based fillers.
Dr Rajkiran Tiwari, R&D Manager at YTC America, is working on PP/bamboo eco-composites for applications including protector covers, relay boxes and holder assemblies. At the Automotive Wire Harness & EDS Conference Detroit 2026, he will present this work in his keynote “Polymer Eco-Filler Composite Materials: Advanced Materials for a Sustainable Future”.
In the interview, Tiwari explains what these materials can already achieve, where their limits lie and which questions around ageing, processing and sustainability still need to be addressed.
Looking ahead five years, what will be the single biggest challenge for the wire harness and EDS industry in North America, and why?
I am not qualified to answer such a general question about the industry. However, from our perspective, achieving carbon neutrality by replacing fossil-based materials with bio-based materials, designing components with circularity in mind, and developing innovative recycling processes for material recovery remain industry-wide challenges.
Which classes of eco-fillers currently have the strongest potential for automotive electrical applications, and which material property is usually the first to become a limiting factor when replacing a conventional formulation?
There are other eco-fillers with fibrous structures that may achieve similar performance. However, it is important to add that, unlike other eco-fillers, bamboo is available throughout the Southern Hemisphere. It is a grass that can be harvested every other year and does not need replanting, as it spreads through rhizomes. Bamboo is as dense and strong as wood from a tree, but due to its rapid growth, bamboo sequesters almost four times more CO2 than a tree such as pine.
We have developed a PP/bamboo eco-composite and are targeting wire-harness components such as protector covers, relay boxes and holder cover assemblies. Our formulations are designed to replace conventional PP/talc composites and have passed OEM specifications for relevant parts. We are currently focused on using these materials for wire-harness assembly components and not for electrical insulation.
We can develop the formulation around the part specification. However, the effects of high humidity and high temperatures need to be evaluated in accordance with OEM specifications. Our development focuses on maintaining a balanced property profile after processing and environmental ageing.
How strongly do filler morphology, particle size, surface treatment and dispersion influence properties such as dielectric performance, creep, impact strength, thermal expansion and processability?
Filler morphology, particle size and filler dispersion strongly affect the properties of PP/bamboo eco-composites. We have systematically studied the effects of these variables during material formulation development. For example, filler morphology, such as aspect ratio, can influence the toughness and stiffness of the eco-composite, while selecting the right type of additive enhances stress transfer between the bamboo and polypropylene, leading to high material strength. Poor filler dispersion can produce agglomerates that act as stress concentrators, leading to part defects during moulding and premature failure. Our target applications are protector covers and relay boxes for physical protection rather than electrical insulation. Therefore, they are primarily evaluated for mechanical, environmental and flammability performance rather than dielectric properties.
Which ageing mechanisms are most likely to expose weaknesses that are not visible in initial material testing – for example, moisture uptake, thermal oxidation, chemicals or repeated thermal cycling?
We have performed extensive studies on eco-composites under high humidity and high temperatures, repeated thermal cycling, ultraviolet light exposure and chemical exposure of moulded parts, as well as recycling. Although some properties degraded after environmental exposure, most of the final properties remained superior to those of PP/talc. For a fair assessment, testing against relevant OEM specifications should be performed to determine whether the current formulation requires further optimisation to stabilise any critical properties.
Because the eco-composite is intended for auxiliary wire-harness components rather than electrical insulation, insulation resistance and dielectric loss have not been evaluated.
How should sustainability be assessed at system level so that a lower-carbon material does not create disadvantages through additional mass, higher scrap rates, longer processing cycles or reduced service life?
This is an excellent question. Sustainability must be evaluated based on the total carbon footprint of the part, including feedstock, service life and the end-of-life scenario. This includes, but is not limited to, feedstock sourcing, eco-filler drying, compounding, moulding cycle time, tool wear, reject and regrind rates, component mass, transportation, durability, repairability, end-of-life options and premature failure. This is why our work is focused not only on replacing conventional materials with PP/bamboo composites, but also on creating a sustainable supply chain and a durable material that can work with existing processing capabilities and fit into current processing protocols. We have performed regrind studies and shown that PP/bamboo injection-moulding scrap can be reintroduced up to five times without a performance penalty. Sustainability and manufacturability need to be developed together.
Finally, what do you personally hope to take away from the Automotive Wire Harness & EDS Conference Detroit 2026?
I hope to learn about OEM material qualification requirements and understand how we can fit eco-composites into this system. I also look forward to discussing with OEMs, suppliers and other attendees the durability of PP/bamboo composites for automotive parts based on rigorous testing. These discussions will help identify additional applications.
