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Hemp fibre has a higher tensile strength and toughness than cotton. Could anyone explain how their different chemical compositions and molecular structure (E.g. beta sheets if any present, bonding,etc.) cause this.

I know cotton is made up of a larger percentage of cellulose, which confuses me as more cellulose is supposed to make fibres strong. I can't find any information using the internet, so it would be extremely helpful if anyone could point me to any that would be relevant.

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Based on what I can find out there from the vast world wide library on the Internet, hemp fiber contains higher amounts of hemicellulose and lignin compounds than cotton. Based on that and the polymer properties thereof, to me these are the obvious reasons why. . .

  1. composition wise they differ the most, and below are a few resource links I found as you requested

I'd research these areas more to see if it adds up for you to make better sense since you specifically asked for pointers. I hope you find this helps you somewhat based on the wording of your inquiry/question per my interpretation.

Sources

EDIT:

I think the big difference molecular composition wise for hemp compared to cotton is as mentioned above "hemp fiber contains higher amounts of hemicellulose and lignin". So to be more specific in terms of bonding and structure with this regard, you should compare those chemical structures and bonding but perhaps their polymer properties is the most obvious reason.

Also per your comment regarding silk as an example, I wanted to point a few things out as well that may be worth you reading up on for a better understanding of general material classifications.

Please check the link at the bottom too for more detail on cellulose, hemicellulose, and lignin.

GENERAL MATERIAL CLASSIFICATIONS

  1. natural cellulose
  2. regenerated cellulose
  3. regenerated plant protein

http://stl.bee.oregonstate.edu/courses/BFP/Class_Slides_W2011/BFP_Lecture6.pdf

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  • $\begingroup$ This is perhaps better suited in the comments section. Could you please expand on your answer so that it completely answer's the OP's question or otherwise write this up as a comment. $\endgroup$
    – Nanoputian
    Commented Oct 17, 2015 at 9:30
  • $\begingroup$ Hey, sorry to bother you again but could you actually be a bit more specific in terms of the bonding and structure of both cotton and hemp? I cannot quite get my head around it. e.g. silk is made primarily from fibroin, which has hydrogen bonded beta sheets of polyalanine chains $\endgroup$ Commented Oct 17, 2015 at 16:10
  • $\begingroup$ @chemlove29310 I added an EDIT to my answer, you may want to consider starting a new question for more specifics in case additional questions start falling out of the scope of your original question. I hope this helps further clarify but for you to get a better understanding, keep breaking everything down where there may be confusion and get granular with your research. You understanding and comprehending this yourself is better than the quick answer or someone else's answer in the long-run. $\endgroup$
    – Facebook
    Commented Oct 17, 2015 at 16:52
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Cotton fibers are composed principally of cellulose, while hemp fibers contain, besides cellulose, hemicellulose.

Cellulose is a linear polymer with glucose repeating units. Its chains are long, packedwith inter-chain hydrogen bonds.So, it's a highly crystalline polymer.

On the other hand, hemicellulose is a highly branched polymer. Its presence increases the strength of the hemp fibers by allowing the internal redistribution of stress that occurs in the fibers. In fact, when replacing the flexible hemicellulose-cellulose-hemicellulose bond by a more rigid cellulose-cellulose bond, the stress is concentrated at the individual bonds and lowers the fiber strength.

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