上个月，一家做再生造粒的厂子拿了一批料过来，让我们帮忙看看还能不能用。
是回收来的尼龙水口料，颜色发灰，粒子表面有点毛。
他们自己先打了一版小样，做出来的卡扣件一掰就断，断口平得像刀切。
车间里还有一股说不清的味道，不是臭，是那种闷的、发酸的气味。
老板在电话里问得很直接：
"这批料是不是废了？"
我没有直接回答，反问他一句："你们测过这批料的相对粘度吗？"
他说没有，只说颜色看着还行就当正常料用了。
这就是问题的起点。回料能不能救，不看颜色，看分子量；不看一次打出来像不像，看断口和粘度。
这一篇把这条线拆开：干燥、扩链、除味，三件事分开做。
一、回料的问题，从头到尾只有一条主线
先把回料的"病历"写清楚。
新料出厂的尼龙，分子链是长的、整齐的。
它每经历一次熔融加工，链就断一次。
挤出造粒一次，注塑成型一次，如果再回收造粒一次、再注塑一次——一根分子链被反复加热剪切的次数，比新料多好几轮。
每一次剪切和热历史，都会把长链切短。
分子量往下掉，最直接的后果是冲击韧性先崩，拉伸强度掉得慢。
所以回料件最典型的表现，正好和开篇那批料对得上：
拉，是拉得断的；一敲、一掰，就碎。
除了分子量，回料还有三个来源带来的麻烦：
含水的回料——回料的储存和来源不可控，含水率的波动比新料大得多。
混杂的回料——不同牌号、不同颜色的边角料混在一起，甚至混进别的材料。
气味——热历史积累的低分子产物、残留的脱模剂与加工助剂，会在加工和使用时释放出来。
所以"救回料"这件事，本质上是三个动作：把水赶走、把断链接回一部分、把气味处理掉。
顺序不能反。
二、扩链剂在两分钟里干了什么
先说"扩链"这两个字在分子层面是什么意思。
尼龙的分子链，两端是官能团。链被切断之后，断口上会露出新的端基。
尼龙扩链剂的作用，是带着两个以上活性基团的小分子，一头咬住一个断口，把两段短链重新接起来。
可以把它想成给断掉的绳子打结——不是把绳子变回原来那么长，而是把两段短的接成一段长的。
一句大白话总结机理：扩链剂不是把料变新，是把断掉的链重新接上；能接回多少，取决于断口多不多。
这里有两句话，决定了这件事的天花板。
其一，扩链剂是消耗品，按断口的数量去反应的。
断口越多，要消耗的扩链剂越多；加得少，只能接上一部分；加得多，多余的扩链剂会去找别的基团反应，把两条链交在一起。
那就从"扩链"变成了"交联"。
其二，扩链只能补救，不能逆转。
一个已经降解到相当程度的回料，加再多的扩链剂，也接不回它最初的分子量。
方向错了，剂量补不回来——这句话在回料这条线上尤其成立。
至于除味，机理完全是另一回事。
气味不是被"盖住"的，是要么在挤出真空段被抽走，要么用吸附类助剂把低分子产物抓住。
这两条路的差别，后面第六段会落成动作。
三、几种救料助剂，各是什么脾气
下面这张表是品类层面的常识区间，不是配方；区间按树脂计，具体牌号以 TDS 为准。
| 品种 | 主要功能 | 适配体系 | 公开添加区间 | 脾气 |
|---|
| 双噁唑啉类扩链剂 | 与羧基端基反应，把断链重新接上 | 回收 PA6、PA66 造粒 | 0.2%–1.0% | 反应快、方向明确；用量过头易造成交联和凝胶 |
| 环氧官能团类扩链剂 | 多官能团，接链同时改善熔体强度 | 回收 PA6、PA66，部分合金回料 | 0.3%–1.0% | 反应相对温和；分批稳定性依赖分散 |
| 异氰酸酯类扩链剂 | 与端基反应，增粘幅度明显 | 特定回料体系 | 0.2%–0.8% | 对水分极敏感，回料不干燥时基本白加 |
| 除味助剂（吸附型 / 反应型） | 降低低分子挥发物带来的气味 | 回收 PA 造粒体系 | 0.2%–1.0% | 只能处理已经产生的气味，改变不了产生气味的源头 |
表里最该看的是最后一名与前两名的差别。
扩链剂动的是分子结构，除味助剂动的是小分子残留。
一个是从源头把链条接长，一个是在末端把已经产生的东西处理掉。
把除味助剂当成万能解，是回料这条线上最常见的误判。
还有一条要提前说清：这三类扩链剂的区间都是"按树脂计"。
把 1% 直接按料的总重算，加出来是够的；但把 0.2% 当成"随便抖一点"，又往往不够。
用量这件事，回料比新料更不能凭感觉——因为回料的断口数量，本来就在波动。
四、需求对选型：怎么验、和谁打架
这张表按"你的回料现在哪里出问题"来找入口。
| 需求（你的回料出了什么问题） | 该往哪类走 | 怎么验 | 常见失效 | 与哪类助剂会打架 |
|---|
| 件发脆、一掰就断 | 双噁唑啉或环氧类扩链剂 | 相对粘度 / 熔指复测，与目标值比 | 接不回来，断口仍发亮 | 与酸性组分残留同用时反应被消耗 |
| 气味重、车间待不住 | 除味助剂 + 加强真空脱挥 | 人工嗅辨评级 + 气味仪；灰分复测 | 气味只是变淡，一加热又出来 | 与抗氧剂争夺挥发物，先做脱挥再考虑加 |
| 熔体强度不够、拉条易断 | 环氧或多官能团类扩链剂 | 熔体强度 / 熔指复测 | 拉条断、粒子大小不一 | 与过量润滑剂同用，熔体表现更差 |
| 黄度上升、颜色发暗 | 先控热历史，再考虑稳定体系 | 色差对比、黄度指数 | 越加工越黄 | 与含卤残留、铜害体系要分开确认 |
| 黑点、凝胶点 | 过滤 + 分选，助剂不是主角 | 过滤网压差、片料目视 | 黑点越打越多 | 与扩链剂过量造成的凝胶叠加 |
表里最该记住的是最后一行。
出现黑点和凝胶点，第一反应不该是"加助剂"，而是"源头分选和过滤"。
因为扩链剂过量本身就会制造凝胶——用助剂去救助剂造成的问题，方向是反的。
再补一句验证上的建议：验证回料方案，起步先测一次相对粘度，中间再测一次。
两次数据的差，比一次的绝对值更有用——它告诉你这批回料在加工里还会掉多少。
五、四种从助剂侧出的失效
失效其一：加了扩链剂，件还是一掰就断。
先看两个方向：扩链剂有没有加进去、以及有多少断口根本接不过来。
更常见的原因在前一步：这批回料没烘干。
水分会先把扩链剂吃掉一部分，剩下的才轮得到断口。
通行解法：先解决干燥，再谈扩链；这一步免费，也最容易被跳过。
失效其二：气味压下去一点点，客户装到机器上一发热又回来了。
根因是除味助剂只处理了已经挥发出来的那部分。
件在高温工况下重新释放，气味就回来了。
这一条值得说直白一点：除味助剂不是香水。它盖不住化学反应继续产生的东西。
通行解法：把真空脱挥做足，控制回料的热历史，除味作为补充手段而不是主防线。
失效其三：同一批料，粘度和颜色忽高忽低。
根因通常有两个：回料的来源与掺比没有定，以及扩链剂分散不均。
回料仓一天进几家的料，配方就一天变几回；这种情况下，任何助剂都稳不住。
通行解法：先把回料的来源、掺比、批次做成一栏记录，再谈助剂方案。
失效其四：黑点越打越多。
根因常常是扩链剂过量造成的局部交联与凝胶，加上螺杆死角与过滤不足。
通行解法：把扩链剂用量往回收，加强过滤，检查螺杆和机头的滞留区。
这一条反过来验证了那句"过量即失效"：多加点不是更保险，是更容易出黑点。
上面四条里，有三条的起手动作是免费的：先干燥、先定掺比、先看过滤。
把免费的先做掉，再去谈加什么助剂。
六、加工与添加：先做什么，后做什么
这一段讲顺序。回料这条线，顺序错了会让助剂互相消耗。
其一，先分选。
不同材质、不同颜色、不同牌号的回料分开走。
混进别的材料（比如 POM、PET 的边角）之后，任何助剂方案都不成立。
其二，先干燥，而且要按实际含水率定。
回料的储存和来源不可控，含水率的波动比新料大得多，不能照抄新料的干燥条件。
其三，先脱水，再扩链。
这一条是顺序里最关键的一步。
扩链剂对水分敏感，回料不干透就加，助剂先去和水反应，轮到断口的就不够了。
干燥在前，扩链在后，中间不要合并成一步做。
其四，扩链剂走主喂料段之前先预分散。
扩链剂用量小，直接抖进主料里最容易不匀。
做成母粒或先与少量载体预混，是这条线上比较稳的做法。
其五，除味放在挤出真空段，不是进料段。
气味要抽走，靠的是真空段把低分子挥发物带走；在进料段加除味助剂，只是换个位置加。
顺序总结成一句话：先分选，再干燥，先接链，后除味，全程把过滤盯住。
七、什么时候不该加，加多了会怎样
先把那句写死：过量即失效。
回料这条线上，扩链剂过量有几个很具体的后果。
其一是交联。 多余的活性基团把不同的链连在一起，熔体流动性往下掉，拉条容易断、粒子大小不均、机头压力升高。
其二是凝胶与黑点。 局部交联形成不熔的颗粒，打出来的件上就是黑点和硬粒。
其三是加工窗口收窄。 交联之后的料对温度更敏感，工艺窗口从宽的变成窄的，量产更难做稳。
所以"多加一点更保险"在回料上是反的：多加一点，是把可用的料变成不可用的料。
再说四种不该救的情况。
其一，来源完全不明、混杂严重的回料。
连里面是什么牌号、混了什么都不知道的时候，助剂只能让批次波动更隐蔽，不能让它变稳。
其二，已经严重降解、粘度掉得非常多的回料。
断口太多，扩链分子接不了那么多。
这类料更适合降级使用（比如做低要求的非受力件），而不是硬拉回原来的档位。
其三，对食品接触或医疗有认证要求的件。
助剂是化学品，这类场合必须回到 GB 4806.7 / ISO 10993 的语境里谈。
回料本身在多数认证体系里就是受限项，加助剂不能让它"合规"。
其四，客户明确约定只能用新料的件。
受力结构件、长期高温件、安全相关件，很多客户的规格书里写得很清楚。
这一类不要去试，试出来的是一次退货。
其五，看换件成本。 藏起来不好换的件，回料方案的余量要给得更宽；好换的件，回料路线才有它的空间。
把这几种情况摆在前面，是为了让人先算"该不该救"，再算"花多少钱救"。
八、这笔救料账怎么算
先给总量级：助剂总成本占改性塑料吨成本的大致区间是 1%–5%。
在回料这条线上，这个比例的意义更直接——它决定的是"这批料进不进得了产线"。
换成一个好懂的说法：一吨回料里加 0.5% 的扩链剂，就是五公斤。
五公斤扩链剂，买的是一批回料能不能用；不用，就是整批料压仓。
所以这笔账不能只算助剂的成本，要把回料与新料的价差、加工损耗、以及良率的变化放在一起算。
这里要主动说清一件反向的事：有些回料，救的成本比它的价差还高。
遇到这种批，诚实的建议是降级使用，而不是把助剂堆上去。
助剂单价一律以 2026 年参考价、随行情波动 为准，具体按当期报价。
配方里的助剂体系按件的工况配——常规助剂常备现货，特殊型号按需配套；你报工况和牌号，料和助剂一次配齐。
读者常问的三句
问：扩链剂加多少？
表里给的是单类助剂的公开常见区间，实际要从低档位试起。
用量是按树脂总重算，而且要先测一次相对粘度再定——不看粘度直接加，等于闭着眼睛调。
问：除味剂能不能代替烘干？
不能。除味处理的是已经产生的小分子，烘干处理的是水。
两者作用的对象不一样，顺序也不能换。
问：回料能不能做到和新料一样？
这条路线能做到的是"性能往回收一部分"，不是消除加工历史。
要求到哪个档位，得用件的验证结果说话；哪些项能追回、哪些项追不回，我们会在方案里写明。
结语
回到开篇那批发灰的水口料。
回料能不能救，判断链其实很短：
先看断口和相对粘度，再定干燥与掺比，然后才是扩链与除味。
再往前一步，还有一个更基本的问题：这批料值不值得救。
三件事分开做——分选、干燥、接链——顺序对了，助剂才有活干。
你手上要是有回料正卡在发脆、有味或黑点上，把三样东西发来就能给个方向：来源与掺比、相对粘度或熔指、以及现在卡住的那一条是力学还是外观。
三行说清我们是谁：做改性尼龙造粒，也做改性塑料常用助剂的配套；料和助剂按件的工况一起配，出了问题一家对账。
回料的诊断与处理顺序，可以一起聊。
Last month, a factory that does recycled pelletizing brought over a batch of material and asked us to help see if it could still be used.
It is recycled nylon sprue material, the color is grayish, and the surface of the granules is a bit rough.
They first made a prototype themselves, and the card buckle broke as soon as it was bent, with the break surface as smooth as if cut by a knife.
There was also an indescribable smell in the workshop, not stinky, but that stuffy, sour smell.
The boss asked very directly over the phone:
Is this batch of material spoiled?
I didn't answer directly, but asked him in return, 'Have you tested the relative viscosity of this batch of material?'
He said no, just said the color looked okay and used it as normal material.
This is the starting point of the problem. Whether recycled material can be salvaged does not depend on color, but on molecular weight; it does not depend on whether it looks good when produced in one go, but on the fracture surface and viscosity.
In this piece, this line is split up: drying, chain extension, and deodorization are done separately.
1. The issue of recycled material has only one main thread from start to finish.
First, clearly write out the returned 'medical record'.
The nylon that comes out of the factory as new material has long and orderly molecular chains.
Each time it undergoes melt processing, the chains break once.
Extrude and pelletize once, injection mold once, and if you recycle and pelletize once more, then injection mold again—the number of times a single molecular chain is repeatedly heated and sheared is several more rounds than that of new material.
Each time it is cut and subjected to heat history, the long chains are shortened.
As the molecular weight decreases, the most immediate consequence is that the impact toughness collapses first, while the tensile strength decreases more slowly.
So the most typical performance of the returned material exactly matches the batch introduced at the beginning:
Pulling it, it can be pulled apart; a knock, a twist, and it breaks.
In addition to molecular weight, regrind also has troubles arising from three other sources:
Moist recycled material — the storage and source of recycled material are uncontrollable, and the moisture content fluctuates much more than that of new material.
Mixed recycled material — scraps of different grades and colors are mixed together, and sometimes even mixed with other materials.
Odor — low molecular products accumulated from thermal history, residual release agents, and processing aids will be released during processing and use.
So the matter of 'recovering material' essentially involves three actions: driving away the water, reconnecting some of the broken links, and dealing with the odor.
The order cannot be reversed.
2. What the chain extender did in two minutes
First, let's talk about what the term 'chain extension' means at the molecular level.
The molecular chains of nylon have functional groups at both ends. After the chains are broken, new end groups will be exposed at the break points.
The role of a nylon chain extender is to act as a small molecule with more than two active groups, with one end gripping a broken site and reconnecting two short chains.
You can think of it as tying a knot in a broken rope—not to make the rope as long as it originally was, but to connect the two short pieces into one long piece.
A plain-language summary of the mechanism: the chain extender does not make the material new; it reconnects the broken chains. How much can be reconnected depends on how many breaks there are.
There are two sentences here that determine the ceiling of this matter.
First, the chain extender is a consumable, and it reacts according to the number of break points.
The more breaks there are, the more chain extenders are needed; if added in small amounts, only part of the chain can be joined; if added in excess, the extra chain extenders will react with other groups and link two chains together.
Then it changed from 'chain extension' to 'cross-linking'.
Second, chain extension can only remedy, not reverse.
Recycled material that has already degraded to a considerable extent cannot regain its original molecular weight, no matter how much chain extender is added.
The direction is wrong, the dose can't be made up — this sentence is especially true on the refeed line.
As for deodorization, the mechanism is a completely different matter.
The odor is not 'covered up'; it is either drawn out when the vacuum section is squeezed, or captured using adsorption-type additives for the low-molecular products.
The difference between these two paths will be enacted in the sixth paragraph later.
3. Several types of fluxing additives, what are their characteristics
The table below shows the common range at the category level, not the formulation; the range is based on resin, and the specific grade should be according to the TDS.
| Variety | Main Function | Adaptation System | Public Add Interval | Temper |
|---|
| bisoxazoline chain extender | React with the carboxyl terminal group to reconnect the broken chain | Recycling PA6 and PA66 granulation | 0.2%–1.0% | Fast reaction, clear direction; excessive usage can easily cause cross-linking and gelation |
| Epoxy functional group chain extenders | Multiple functional groups, chain extension simultaneously improves melt strength | Recycling PA6, PA66, and some alloy scrap | 0.3%–1.0% | The reaction is relatively mild; the stability of batches depends on dispersion |
| Isocyanate chain extenders | Reacting with terminal base, the viscosity increase is significant | Specific recirculation system | 0.2%–0.8% | Extremely sensitive to moisture; basically useless if the recycled material is not dry. |
| Deodorizing Additives (Adsorptive / Reactive) | Reduce the odor caused by low molecular weight volatiles | Recycling PA Granulation System | 0.2%–1.0% | Can only deal with odors that have already occurred, cannot change the source of the odor |
What should be looked at most is the difference between the last place and the first two places.
The chain extender acts on the molecular structure, while the deodorizing additive acts on small molecule residues.
One is to extend the chain from the source, and the other is to deal with what has already been produced at the end.
Treating deodorizing additives as a universal solution is the most common misjudgment on the recycled material production line.
There is one more point that needs to be clarified in advance: the ranges for these three types of chain extenders are all 'calculated based on resin'.
Calculating 1% directly based on the total weight of the material is enough; but if 0.2% is treated as 'just sprinkle a little,' it often isn't enough.
When it comes to dosage, recycled material should not rely on intuition more than new material does — because the number of break points in recycled material naturally fluctuates.
4. Demand on selection: how to test, and who to argue with
This table looks for the entry based on 'Where is your returned material currently having problems'.
| Requirement (What went wrong with your feedback) | Which direction should I go? | How to verify | Common Failures | Which types of additives will conflict |
|---|
| Brittle, breaks as soon as you snap it | Bisoxazoline or epoxy chain extenders | Relative viscosity / Melt index retest, compared with target value | Can't bring it back, the break still shines | The reaction is consumed when used together with acidic component residues |
| Strong odor, can't stay in the workshop | Deodorizing additive Enhanced vacuum stripping | Manual olfactory grading Odor meter; ash remeasurement | The smell just fades, but comes out again when heated. | Compete with antioxidants for volatiles, first do volatilization removal and then consider addition |
| Melt strength is insufficient, and the drawn strips are easy to break | Epoxy or polyfunctional chain extenders | Melt strength / Melt flow index retest | String tearing, uneven particle size | When used with excessive lubricant, the melt performs worse |
| Increasing yellowness, darkening color | First control the thermal history, then consider stabilizing the system. | Color difference comparison, yellowness index | The more it is processed, the more yellow it becomes | Needs to be confirmed separately from systems with halogen residues and copper contamination |
| Black spots, gel spots | Filtration and sorting, additives are not the main actors | Filter screen pressure difference, visual inspection of sheets | The black spots keep getting more and more | Gel stacking caused by excessive crosslinker |
The last line is what should be remembered most.
When black spots and gel spots appear, the first reaction should not be 'adding additives,' but 'source sorting and filtration.'
Because an excess of chain extenders itself will create gels—using an additive to fix a problem caused by another additive is going in the wrong direction.
One more piece of advice regarding verification: for the verification of the recycled material plan, first measure the relative viscosity once at the beginning, and then measure it once more in the middle.
The difference between two sets of data is more useful than a single absolute value—it tells you how much material will still be lost in processing.
5. Four types of failures caused by auxiliary agents
Failure point one: even after adding a chain extender, the piece still breaks with just a snap.
First, look at two directions: whether the chain extender has been added, and how many broken ends simply can't be connected.
A more common reason lies in the previous step: this batch of recycled material wasn't dried.
The moisture will first consume part of the chain extender, and only the remainder will reach the break point.
Common solution: First address drying, then discuss chain extension; this step is free and also the easiest to skip.
Failure point two: The smell is suppressed a little bit, but once the customer uses it on the machine, it comes back as soon as it heats up.
The root cause is that the deodorizing additive only dealt with the part that had already volatilized.
When the part is released again under high-temperature conditions, the odor returns.
This one deserves to be said more plainly: deodorizing additives are not perfume. They cannot cover up the things produced by ongoing chemical reactions.
Common approach: thoroughly perform vacuum degassing, control the thermal history of the return material, and use deodorization as a supplementary measure rather than the main defense.
Failure Three: The same batch of material has fluctuating viscosity and color.
There are usually two root causes: the source and blending ratio of the recycled material are not defined, and the chain extender is not evenly dispersed.
The number of suppliers feeding the silo in a day determines how many times the formula changes in a day; under such circumstances, no additive can remain stable.
Common approach: First, record the source, blending ratio, and batch of the recycled material in one column, then discuss the additives plan.
Ineffectiveness Four: The more you treat blackheads, the more they appear.
The root cause is often local cross-linking and gelation caused by excessive chain extenders, combined with screw dead spots and insufficient filtration.
Common solution: Reduce the amount of chain extender, improve filtration, and check the retention areas of the screw and the machine head.
This in turn validates the saying 'too much is ineffective': adding more is not safer, it is more likely to cause black spots.
Among the four items above, three of them have free initial actions: drying first, setting the mix ratio first, and checking the filtration first.
Finish the free ones first, then talk about adding any additives.
6. Processing and Additives: What to Do First, What to Do Later
This section talks about the sequence. In returning material to this line, the wrong sequence will cause the additives to consume each other.
First, sort them.
Recycled materials of different materials, different colors, and different grades should be kept separate.
After mixing in other materials (such as scraps of POM or PET), no additive scheme will work.
Second, dry it first, and also determine it according to the actual moisture content.
The storage and source of recycled material are uncontrollable, and the moisture content fluctuates much more than that of new material, so the drying conditions of new material cannot be directly applied.
Third, dehydrate first, then expand the chain.
This is the most crucial step in the sequence.
Chain extenders are sensitive to moisture; if the recycled material isn't thoroughly dried before adding, the additive reacts with the water first, and when it's time for the chain break, there isn't enough left.
Dry first, then extend the chain; do not combine them into one step in between.
Fourth, the chain extender should be pre-dispersed before going to the main feeding section.
The amount of chain extender is small, and directly shaking it into the main material is the easiest way to make it uneven.
Making it into a masterbatch or pre-mixing it with a small amount of carrier is a relatively stable practice on this line.
Fifth, the flavoring should be added in the extrusion vacuum section, not in the feeding section.
To remove the odor, it relies on the vacuum section to carry away low-molecular volatile substances; adding deodorizing additives in the feeding section is just adding them in a different position.
Summarized in one sentence in order: first sort, then dry, first connect the chain, then remove the odor, and keep an eye on the filtration throughout.
7. When should it not be added, and what happens if too much is added
First write that sentence as fixed: Overdose causes ineffectiveness.
On the re-material line, excessive chain extender has several very specific consequences.
The first is crosslinking. Excess active groups link different chains together, reducing melt flowability, making the strands easy to break, causing uneven particle size, and increasing the pressure at the machine head.
The second is gel and black spots. Localized cross-linking forms non-melting particles, and the produced parts have black spots and hard granules.
The third is the narrowing of the processing window. The material after cross-linking is more sensitive to temperature, and the process window changes from wide to narrow, making mass production more difficult to stabilize.
So 'adding a little more to be safer' is the opposite when it comes to rework materials: adding a little more turns usable material into unusable material.
Let's also talk about four situations where one should not rescue.
First, recycled material with completely unknown sources and serious contamination.
When you don't even know what grade is inside or what it is mixed with, additives can only make batch fluctuations more hidden, not make it stable.
Second, regrind that has already severely degraded and whose viscosity has dropped significantly.
There are too many breakpoints, and the chain-extending molecules can't connect to that many.
This type of material is more suitable for downgraded use (for example, making non-load-bearing parts with low requirements), rather than forcibly returning it to its original grade.
Third, items that require certification for food contact or medical use.
Additives are chemicals, and in such cases, the discussion must return to the context of GB 4806.7 / ISO 10993.
Reclaimed material itself is a restricted item in most certification systems, and additives cannot make it 'compliant'.
Fourth, the customer clearly stipulated that only new materials can be used for the parts.
Load-bearing structural parts, long-term high-temperature parts, safety-related parts—many customers' specifications clearly state these in their specifications.
Don't try these types; the result is a single return.
Fifth, look at the cost of replacing parts. For parts that are hard to replace, allow more margin for the return plan; For parts that are easy to replace, the return route has room for it.
Putting these situations up front is to help people first calculate "whether to save them," then "how much money to save."
Eighth, how to calculate this salvage account ?
First, give the total volume: The approximate range of additives in the cost per ton of modified plastic is 1%–5%.
On the recycled material line, this ratio is more direct—it determines whether "this batch of material can enter the production line."
To put it simply: adding 0.5% chain extender to one ton of recycled material equals five kilograms.
For five kilograms of chain extender, you buy a batch of recycled material to see if it can be used; if not, the whole batch is compressed into the silo.
So this account can't just include the cost of additives; you need to factor in the price difference between recycled and new materials, processing losses, and yield changes.
Here, I want to proactively clarify a reverse thing: some recycled materials cost more than their price difference.
When encountering such batches, the honest advice is to downgrade the use rather than pile up additives.
The unit price of additives is always based on the 2026 reference price and market fluctuations, with the current period's quoted price for specifics.
The additive system in the formula is tailored to the working conditions of the piece—regular additives are always in stock, special models are matched as needed; You state the operating conditions and grade, and the materials and additives are all mixed at once.
Three Frequently Asked Questions from Readers
Question: How much chain extender should be added?
The table shows the publicly available range for single types of additives; in practice, start testing from the lowest level.
The amount used is calculated based on the total resin weight, and the relative viscosity must be measured before setting—adding it without checking viscosity is like adjusting with your eyes closed.
Question: Can deodorizer replace drying?
No. Deodorizing treats already formed small molecules, while drying treats water.
The targets of the two are different, and the order cannot be changed.
Question: Can recycled material be made the same as new material?
This route achieves "partial performance recovery," not eliminating processing history.
The required level depends on the verification results of the parts; We'll specify in the plan which items can be recovered and which cannot.
Conclusion
Back to the batch of ash sprue material at the beginning.
Whether recycled material can be saved, the chain is actually very short:
First, check the fracture and relative viscosity, then determine drying and blending, and only then expand the chain and remove odor.
Moving forward, there's a more fundamental question: Is this batch worth saving from?
Split the three tasks separately—sorting, drying, chain joining—only when the order is right does the additives get work.
If you have recycled material stuck on brittle, smelly, or black spots, send in three things and you can give a direction: source and blend, relative viscosity or melting index, and whether the current stuck item is mechanical or appearance.
Three Lines clarify who we are: we do modified nylon pelletizing, and also provide common auxiliary materials for modified plastics; Materials and additives are mixed according to the working conditions of the piece, and if there is a problem, one company can reconcile the accounts.
You can discuss the diagnostic and processing sequence of recycled materials
