8
Fuels & Lubes International Quarter Three 2015
for this, he said. New
additive chemistry has
to avoid being entangled
with existing additive
molecules, he added.
Microencapsulation could
help solve this problem
and could help isolate
some chemistry to be able
to function, Hsu explained.
“It’s the same
chemistry. But now you
can reduce waste… and
safeguard synergistic
additive combinations,
hence reducing cost,
and [have a] far better
delivery system,” said
Hsu, a professor of
Engineering and Applied
Science at GWU. He gave
a presentation at the
Annual Meeting of the
Society of Tribologists and
Lubrication Engineers
(STLE) in Dallas, Texas,
U.S.A. in May.
Time release is another
important feature of
microcapsules, as it
allows additives to be
replenished over time.
So even though there is
no new chemistry, the
delivery method of the
additive to the lubricated
system will change. Hsu,
a well-known tribologist,
likens it to changing the
interface.
In the current lubricant
formulations, it has
become very difficult to
add a small amount of
new additive to change
lubricant performance,
Hsu explained, because
the “chemical soup”
formed by the additives in
the lubricant has become
so big and so complex that
it is difficult to add any
new molecules.
Friction modifiers, for
example, are known to
degrade as a function of
time, gradually losing
their friction modification
ability. Microcapsules
have the potential to
replenish additional
friction modifiers to
prolong the effectiveness
of the additive, thereby
increasing fuel economy.
Capsules have to be tough
and strong to endure the
high temperature, high
shear environment of
the lubrication system.
According to Hsu, several
additives can be put into a
single capsule, forming a
mini-package to reinforce
the lubricant when the
capsules break, releasing
the protected additives.
In the current system,
there is not enough
control on how much
additive remains as a
function of time, he said.
Microencapsulation can
hopefully help to deliver
the additive at the right
place and at the right
time.
Hsu suggested that
microencapsulation
technology may provide
high performance, long
drain oils at a lower
cost. The capsules can
be released by various
triggering mechanisms
built into the polymer
chemistry and will break
up when the acidity
becomes high, or under
some pre-specified
temperatures.
While this technology
is currently in the
testing phase and not
yet commercialised, it is
an exciting development
that could potentially
open up a new avenue to
deliver additives to the
lubrication system.
月，他在美国德克萨斯州达拉
斯的摩擦学家和润滑油工程师
年度大会发作了发言。
微型胶囊的另一个特性的缓
释，它使得润滑油在使用过程
中能补充添加剂含量。因此，
虽然没有新的化学品加入，但
受润滑的系统的添加剂释放系
统发生了变化，就像是改变了
界面。Hsu是一名知名的摩擦
学家。
在目前的润滑油配方中，想
通过添加少量的新添加剂以改
变润滑油性能很难，Hsu解释
说，因为润滑油中的添加剂“化
学汤”非常大而复杂，很难再加
进任何新的分子。
例如，摩擦改进剂会随时
间而降解，逐步丧失摩擦改进
能力。微型胶囊具有在较长时
间内缓释从而补充添加剂的能
力，可以延长添加剂的有效作
用时间，提高燃油经济性。胶
囊必须较为坚固以抵抗润滑系
中的高温、高剪切环境。据Hsu
说，可以把多种添加剂放入一
个胶囊，形成一个微型复合添
加剂包来增强润滑剂性能；胶
囊破裂后会释放出受到保护的
添加剂。
在目前的系统中，随时间
推移，无法控制残留的添加剂
量，他说。微型胶囊可以有希
望在适当的时间在适当的地方
释放添加剂。
Hsu认为微型胶囊技术可以
低成本地现实高性能、长换油
期。胶囊可以根据聚合物内在
的化学结构采用多种触发机制
来释放添加剂，如随酸度升
高，或在预定的温度下破裂。
这项技术目前尚处于测试阶
段，还没有商业化，但这是一
项令人鼓舞的进展，有可能为
润滑油中释放添加剂打开一条
新路。
Stephen Hsu
