> For the complete documentation index, see [llms.txt](https://wiki.polymaker.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.polymaker.com/polymaker-wiki/polymaker-wiki-zh/da-yin-ji-qiao/material-science/what-are-polymers.md).

# 什么是聚合物？

在本节中，我们将采用材料科学的方法，探讨3D打印中遇到的常见问题和挑战。本页旨在为常见问题提供更多科学知识，以便轻松克服它们。

首先，了解3D打印中使用的材料至关重要：聚合物。

聚合物是大型分子，或称“大分子”，由大量重复单元（称为“单体”）在聚合过程中形成。聚合过程通过化学反应将单体分子键合在一起，形成聚合物的骨架。

所生产的聚合物类型可能因构成它们的单体化合物的化学性质和组成而异。单体之间形成的键将被定义为共价键。

![3D Printing Polymer](https://cdn.shopify.com/s/files/1/0548/7299/7945/files/monomers_480x480.png?v=1709320843)

聚合物可分为两大类：热固性塑料和热塑性塑料。

热固性塑料是聚合物，它们从软固体或粘性液体预聚物不可逆地固化成固体聚合物。固化过程也称为交联，通过化学反应连接所有单体和预聚物，形成网络结构。固化后的热固性塑料不能再熔化，通常不能进行热加工。

![Thermoset Thermoplastic](https://cdn.shopify.com/s/files/1/0548/7299/7945/files/thermoset_thermoplastic_600x600.png?v=1709320909)

热塑性塑料是受热变软、冷却变硬的材料。热塑性塑料可以多次加热、塑形和冷却，其化学性质或机械性能变化极小。与热固性塑料中每个聚合物链都通过共价键相互连接不同，热塑性塑料的聚合物链通过较弱的键相互连接，这些键将被定义为非共价键。

聚合物还可以根据其微观结构分为两大类：

### 无定形和半结晶

区分不同热塑性塑料的方法之一是通过它们的微观结构，这可以定义聚合物的性质和行为。

**无定形**

无定形聚合物的特点是没有长程有序性。这意味着聚合物链是随机取向的。

一般来说，透明塑料通常由无定形聚合物制成，例如PMMA、PS和PC。

![Amorphous](https://cdn.shopify.com/s/files/1/0548/7299/7945/files/Amorphous_480x480.png?v=1709320953)

**半结晶**

半结晶聚合物的特点是具有有序结构，其中包含称为“晶体”的结构域。

晶体是聚合物链的有序且紧密堆积的集合。晶体域和无定形域在半结晶聚合物中并存，因此称为“半”。结晶区域的比例由结晶度定义。半结晶聚合物的一个特定特征是，结晶度可以极大地影响其机械和热性能。

![semicrystalline](https://cdn.shopify.com/s/files/1/0548/7299/7945/files/Semi-crystalline_480x480.png?v=1709321000)


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