Thermal conduction in an electrical insulating polymer

电绝缘聚合物中的热传导

• 批准号: EP/K034405/1
• 负责人: Sara Ronca
• 金额: $ 12.57万
• 依托单位: Loughborough University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FK034405%2F1
• 关键词: Thermal; conduction; electrical; insulating; polymer

The drive of many electronic technologies towards miniaturisation, weight reduction and integration has increased the need for smart materials that can cope with new arising issues, such as the need for fast heat dissipation. The same issue is faced in electric motors and generators, automotive, solar panels, batteries, and heat exchangers in power generation. Metals can be used due to their high thermal and electrical conductivity, but they are expensive and rather heavy: for this reason, research is trying to replace metals with cheaper and lighter materials. An obvious choice is to use polymeric materials (plastic) that, in addition to the lower cost and weight, also have the advantage of being easily processable in a variety of shapes and sizes. However, polymers usually have very low thermal conductivities and suitable fillers (metal or ceramic particles being the most common ones) are added to increase the conductivity to the desired levels. The use of composites has drawbacks related to the need of further processing of the material, the change in mechanical properties due to the addition of fillers and the problems related to the end-of-life disposal. Moreover, the amount of fillers should be carefully controlled if the target is to get a material that is both thermally conductive and electrically insulating.In principle, heat conduction could happen in polymers through the mechanism of lattice vibrations: the reason for the very low conductivity observed for these materials is mainly related to the random orientation and entanglement of polymer chains. It has been recently demonstrated that, if the polymer chains of a simple polymers such as polyethylene can be aligned, high thermal conductivity can be achieved in the direction of alignment. In order to achieve high conductivities, it is also desirable to have very long polymer chains, to minimise lattice defects brought by the chain ends. This is the case for Ultra High Molecular Weight Polyethylene (UHMWPE): however, the chain alignment process for this material is rather cumbersome and demands the use of large amounts of solvent to 'disentangle' the very long chains.The proposed research aims to overcome these issues, building on our success at fine tuning the molecular characteristics and improving the processability of UHMWPE. We have devised a synthetic strategy that enables us to directly obtain UHMWPE with a reduced number of entanglements. We have demonstrated that this material can be easily processed, without the need for any solvent, to give tapes and filaments with high chain alignment. Moreover, our method offers the unprecedented possibility to tailor the molecular weight of the polymer as well as the chain alignment, by simply changing the reaction or processing conditions. In this project, we wish to apply the knowledge that we have developed on "disentangled UHMWPE" to study the effects that molecular structure and orientation have on the thermal conductivity of this material. The results coming from this project will enable us to realise a light-weight, cheap, easy to process and to recycle material where the thermal conductivity can be tuned in a range of useful values by suitable modifications of the synthetic and processing steps.

许多电子技术向小型化、轻量化和集成化方向发展，增加了对智能材料的需求，这些材料可以应对新出现的问题，例如快速散热的需求。发电中的电动机和发电机、汽车、太阳能电池板、电池和热交换器也面临着同样的问题。金属因其高导热性和导电性而可以使用，但它们价格昂贵且相当重：因此，研究正在尝试用更便宜和更轻的材料代替金属。一个明显的选择是使用聚合物材料（塑料），除了成本和重量较低之外，还具有易于加工成各种形状和尺寸的优点。然而，聚合物通常具有非常低的导热率，并且添加合适的填料（最常见的是金属或陶瓷颗粒）以将导热率提高到所需水平。复合材料的使用存在一些缺点，包括需要对材料进行进一步加工、由于添加填料而导致机械性能发生变化以及与报废处理相关的问题。此外，如果目标是获得既导热又电绝缘的材料，则应仔细控制填料的量。原则上，聚合物中可以通过晶格振动机制发生热传导：这些材料观察到的导热率非常低的原因主要与聚合物链的随机取向和缠结有关。最近已经证明，如果简单聚合物(例如聚乙烯)的聚合物链可以排列，则可以在排列方向上实现高导热性。为了实现高电导率，还需要具有非常长的聚合物链，以最小化链端带来的晶格缺陷。超高分子量聚乙烯 (UHMWPE) 就是这种情况：然而，这种材料的链排列过程相当繁琐，需要使用大量溶剂来“解开”很长的链。本研究旨在克服这些问题，建立在我们成功微调分子特性和提高 UHMWPE 加工性能的基础上。我们设计了一种合成策略，使我们能够直接获得 UHMWPE，同时减少缠结数量。我们已经证明，这种材料可以轻松加工，无需任何溶剂，即可获得具有高度链排列的带材和长丝。此外，我们的方法提供了前所未有的可能性，通过简单地改变反应或加工条件来定制聚合物的分子量以及链排列。在这个项目中，我们希望应用我们在“解缠结UHMWPE”方面开发的知识来研究分子结构和取向对该材料导热性的影响。该项目的结果将使我们能够实现一种轻质、廉价、易于加工和回收的材料，通过对合成和加工步骤进行适当的修改，可以将导热率调整到一系列有用的值。

项目成果

Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene: Influence of Reaction Medium on Material Properties

• DOI: 10.1155/2017/7431419
• 发表时间: 2017-01-01
• 期刊: INTERNATIONAL JOURNAL OF POLYMER SCIENCE
• 影响因子: 3.3
• 作者: Forte, Giuseppe;Ronca, Sara
• 通讯作者: Ronca, Sara

Oriented ultra-high molecular weight polyethylene/gold nanocomposites: Electrical conductivity and chain entanglement dynamics

• DOI: 10.3144/expresspolymlett.2021.42
• 发表时间: 2021-06-01
• 期刊: EXPRESS POLYMER LETTERS
• 影响因子: 3.3
• 作者: Drakopoulos, S. X.;Psarras, G. C.;Ronca, S.
• 通讯作者: Ronca, S.

Solvent-Free Solid-State-Processed Tapes of Ultrahigh-Molecular-Weight Polyethylene: Influence of Molar Mass and Molar Mass Distribution on the Tensile Properties

• DOI: 10.1021/acs.iecr.5b01469
• 发表时间: 2015-08-05
• 期刊: INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
• 影响因子: 4.2
• 作者: Ronca, Sara;Forte, Giuseppe;Rastogi, Sanjay
• 通讯作者: Rastogi, Sanjay

Electrospun Nanofibres Containing Antimicrobial Plant Extracts.

• DOI: 10.3390/nano7020042
• 发表时间: 2017-02-15
• 期刊: Nanomaterials (Basel, Switzerland)
• 作者: Zhang W;Ronca S;Mele E
• 通讯作者: Mele E

Entanglement dynamics in ultra-high molecular weight polyethylene as revealed by dielectric spectroscopy

• DOI: 10.1016/j.polymer.2018.07.021
• 发表时间: 2018-08-15
• 期刊: POLYMER
• 影响因子: 4.6
• 作者: Drakopoulos, Stavros X.;Psarras, Georgios C.;Ronca, Sara
• 通讯作者: Ronca, Sara