Flow induced crystallisation in polymers: from molecules to processing

聚合物中的流动诱导结晶：从分子到加工

• 批准号: EP/P005403/1
• 负责人: Richard Graham
• 金额: $ 119.48万
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FP005403%2F1
• 关键词: Flow; induced; crystallisation; polymers; molecules

Polymer processing is a multi-billion pound, world-wide industry, manufacturing products used by virtually every person in the developed world (and beyond) on a daily basis. This vital sector of the UK economy will gain a significant competitive advantage from a molecular understanding of how polymers crystallise during processing, as it will enable stronger, lighter, more durable and more easily recycled plastic products. In this proposal we will overcome the key experimental, simulation and numerical issues in understanding polymer crystallisation to deliver a molecular based, predictive platform for the processing of semi-crystalline polymers. We will tightly integrate a family of progressively coarse-grained simulations and models, covering all relevant lengthscales within a single project. This will displace the current sub-optimal semi-empirical approaches in polymer processing and enable molecular design of polymer products, through choice of processing conditions. By facilitating the manufacture of polymer products with tailored properties this program will provide a critical competitive advantage to this important industry.Polymers are long-chain molecules, formed from connecting together a large number of simple molecules. These long-chain molecules are at the heart of the multi-billion pound plastics industry. Semi-crystalline polymers make up a very significant fraction of the worlds production of synthetic polymers. Unlike simple molecules, the connectivity of polymer molecules means they crystallise into a composite structure of crystalline and amorphous regions. The proportion of amorphous and crystalline material, along with the arrangement and orientation of the crystals, is collectively known as the morphology. The crystal morphology strongly influences strength, toughness, permeability, surface texture, transparency, capacity to be recycled and almost any other property of practical interest. Furthermore, polymer crystallisation is radically influenced by the flows that are ubiquitous in polymer processing. Flow drastically enhances the rate at which polymers crystallise and has a profound effect on their morphology. Flow distorts the configuration of polymer chains and this distortion breaks down the kinetic barriers to crystallisation and directs the resulting morphology.Understanding polymer crystallisation is a formidable problem. The huge range of relevant lengthscales ranges from the size of a monomer (nm) up to near macroscopic crystals (micro-metres). The range of timescales is even wider, ranging from the monomer relaxation time (ns) to nucleation (hours at low under-cooling). Our project will involve extensive multiscale modelling, supported at each level by experiments specifically designed to address key modelling issues. Our experiments will involve controlled flow geometries, the systematic variation of molecular weight and the probes of both nucleation and overall crystallisation. Close integration of experiments and all levels of modelling is a key feature.We will develop an interrelated hierarchical family of multiscale models, spanning all relevant lengthscales and delivering results where piecewise approaches have been ineffective. Each technique will be tightly integrated with its neighbours, retaining the molecular basis of the models while progressively addressing increasingly challenging systems. This will cumulate with the low-undercooling and high-molecular weights that are characteristic of polymer processing. Each simulation will use a rare event algorithm to dramatically increase the nucleation rate, the cause of the very long timescales. Insight from the most detailed models will guide the development of faster modelling. At the highest coarse-graining, the program will derive models suitable for computational modelling of polymer processing. Using these models in cutting-edge finite element code, we will compute FIC behaviour in polymer processing geometries.

聚合物加工是一个价值数十亿磅的世界性行业，生产的产品几乎每天都被发达国家（及其他地区）的每个人使用。英国经济的这一重要部门将从对聚合物在加工过程中如何结晶的分子理解中获得显着的竞争优势，因为它将使塑料产品更坚固，更轻，更耐用，更容易回收。在这项提案中，我们将克服理解聚合物结晶的关键实验、模拟和数值问题，为半结晶聚合物的加工提供一个基于分子的预测平台。我们将紧密集成一系列逐步粗粒度的模拟和模型，涵盖单个项目中的所有相关长度尺度。这将取代目前聚合物加工中的次优半经验方法，并通过选择加工条件实现聚合物产品的分子设计。通过促进具有定制特性的聚合物产品的制造，该计划将为这一重要行业提供关键的竞争优势。聚合物是长链分子，由大量简单分子连接在一起形成。这些长链分子是数十亿磅塑料工业的核心。半结晶聚合物在世界合成聚合物生产中占很大比例。与简单分子不同，聚合物分子的连接性意味着它们结晶成结晶和非晶区域的复合结构。非晶和晶体材料的比例，连同晶体的排列和取向，沿着统称为形态。晶体形态强烈影响强度、韧性、渗透性、表面纹理、透明度、回收能力和几乎任何其他具有实际意义的性质。此外，聚合物结晶受到聚合物加工中普遍存在的流动的根本影响。流动大大提高了聚合物结晶的速率，并对其形态产生深远的影响。流动扭曲了聚合物链的构型，这种扭曲打破了结晶的动力学障碍，并指导了所得的形态。相关的长度尺度范围很大，从单体的尺寸（nm）到接近宏观晶体（微米）。时间尺度的范围甚至更宽，从单体弛豫时间（ns）到成核（在低过冷下的小时数）。我们的项目将涉及广泛的多尺度建模，在每个层面上都有专门设计用于解决关键建模问题的实验支持。我们的实验将涉及控制流动的几何形状，分子量的系统变化和成核和整体结晶的探针。实验和建模的各个层面的紧密结合是一个关键特征。我们将开发一个相互关联的多尺度模型的层次家庭，跨越所有相关的长度尺度，并在分段方法无效的情况下提供结果。每种技术都将与相邻技术紧密结合，保留模型的分子基础，同时逐步解决日益具有挑战性的系统。这将与低过冷度和高分子量累积，这是聚合物加工的特征。每次模拟都将使用罕见事件算法来显著增加成核率，这是非常长的时间尺度的原因。从最详细的模型中获得的见解将指导更快建模的开发。在最高的粗粒化，程序将推导出适合聚合物加工计算建模的模型。在尖端的有限元代码中使用这些模型，我们将计算聚合物加工几何形状中的FIC行为。

项目成果

Nonlinear rheology of polydisperse blends of entangled linear polymers: Rolie-Double-Poly models

• DOI: 10.1122/1.5052320
• 发表时间: 2019-01-01
• 期刊: JOURNAL OF RHEOLOGY
• 影响因子: 3.3
• 作者: Boudara, Victor A. H.;Peterson, Joseph D.;Read, Daniel J.
• 通讯作者: Read, Daniel J.

Direct observation of long chain enrichment in flow-induced nuclei from molecular dynamics simulations of bimodal blends.

从双峰共混物的分子动力学模拟中直接观察流动诱导核中的长链富集。

• DOI: 10.1039/d0sm01361g
• 发表时间: 2021
• 期刊: Soft matter
• 影响因子: 3.4
• 作者: Anwar M

Understanding flow-induced crystallization in polymers: A perspective on the role of molecular simulations

• DOI: 10.1122/1.5056170
• 发表时间: 2019-01-01
• 期刊: JOURNAL OF RHEOLOGY
• 影响因子: 3.3
• 作者: Graham, Richard S.

Modelling contraction flows of bi-disperse polymer blends using the Rolie-Poly and Rolie-Double-Poly equations

使用 Rolie-Poly 和 Rolie-Double-Poly 方程模拟双分散聚合物共混物的收缩流

• DOI: 10.1007/s13367-019-0021-6
• 发表时间: 2019
• 期刊: Korea-Australia Rheology Journal
• 影响因子: 1.3
• 作者: Azahar A

Modelling flow-enhanced crystallisation during fused filament fabrication of semi-crystalline polymer melts

• DOI: 10.1016/j.addma.2018.10.018
• 发表时间: 2018-12-01
• 期刊: ADDITIVE MANUFACTURING
• 影响因子: 11
• 作者: McIlroy, C.;Graham, R. S.
• 通讯作者: Graham, R. S.